Flare Sim

COPYRIGHTThe copyright in this manual and its accompanying software are the property of Softbits Consultants Ltd with all rights reserved. Both this manual and the software have been provided pursuant to a License Agreement containing restrictions on use.

Softbits Consultants Ltd reserves the right to make changes to this manual or its accompanying software without obligation to notify any person or organisation.

No part of this manual may be reproduced, transmitted, transcribed, stored in a retrieval system or translated into any other language in any form or by any means, or disclosed to third parties without the prior written consent of Softbits Consultants Ltd.

WARRANTYSoftbits Consultants Ltd or its agents will replace any defective manual, program disks within 90 days of purchase of the product providing that proof of purchase is evident. Neither Softbits Consultants Ltd nor its agents or dealers make any warranty, implied or otherwise, with respect to the software or results generated by the software.

This program is intended for use by a qualified engineer to aid the design and analysis of flare systems. The results calculated by this program may not be reliable if the input data has not been appropriately specified or if the program is used without regard to its documented limitations.

It is the responsibility of the user to interpret the results generated by this program. Softbits Consultants Ltd shall bear no liability for special, indirect, incidental, consequential, exemplary or punitive damages arising from use of this software.

The governing law of this warranty shall be that of England.

ACKNOWLEDGEMENTSSoftbits Consultants Ltd would like to thank Mr. John F. Straitz III and the National Airoil Company and GBA Ltd of Slough for assistance with some algorithms within the software.

Windows XP, Vista and Windows 7 are registered trademarks of Microsoft Corporation.

Copyright Softbits Consultants Ltd, 1989, 1990, 2002, 2006, 2008, 2010

1 Introduction.................................................. 1-1

1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-41.2 Program Overview. . . . . . . . . . . . . . . . . . . . . . 1-71.3 Documentation Overview . . . . . . . . . . . . . . . 1-13

2 Installation.................................................... 2-1

2.1 Installation Requirements . . . . . . . . . . . . . . . . 2-32.2 Installing Flaresim-Single User . . . . . . . . . . . . 2-42.3 Installing Flaresim - Network . . . . . . . . . . . . . 2-252.4 Flaresim File Locations . . . . . . . . . . . . . . . . . 2-40

3 Getting Started............................................. 3-1

3.1 Simple Flare Stack Design . . . . . . . . . . . . . . . 3-43.2 Sonic Tip Design . . . . . . . . . . . . . . . . . . . . . . 3-183.3 Two Tip Design . . . . . . . . . . . . . . . . . . . . . . . 3-233.4 Working With Isopleths . . . . . . . . . . . . . . . . . 3-263.5 Welltest Burner Design . . . . . . . . . . . . . . . . . 3-363.6 Gas Dispersion . . . . . . . . . . . . . . . . . . . . . . . 3-47

4 Interface........................................................ 4-1

4.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-34.2 Menu Bar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-74.3 Multiple Case Views . . . . . . . . . . . . . . . . . . . 4-104.4 Tool Bars . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-114.5 Log Panels . . . . . . . . . . . . . . . . . . . . . . . . . . 4-144.6 File Dialogs . . . . . . . . . . . . . . . . . . . . . . . . . . 4-154.7 About View . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20

Table of Contents

1

2

5 General Setup .............................................. 5-1

5.1 Case Navigator View. . . . . . . . . . . . . . . . . . . . 5-35.2 Case Summary View. . . . . . . . . . . . . . . . . . . . 5-85.3 Setup Wizard. . . . . . . . . . . . . . . . . . . . . . . . . 5-105.4 Preferences. . . . . . . . . . . . . . . . . . . . . . . . . . 5-265.5 Component Management View . . . . . . . . . . . 5-40

6 Fluids ............................................................ 6-1

6.1 Fluid View . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-46.2 Assist Fluid View . . . . . . . . . . . . . . . . . . . . . . 6-11

7 Environment................................................. 7-1

7.1 Environment View . . . . . . . . . . . . . . . . . . . . . . 7-47.2 Environment Summary View . . . . . . . . . . . . . 7-15

8 Stacks ........................................................... 8-1

8.1 Stack View. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-48.2 Stack Summary View . . . . . . . . . . . . . . . . . . . 8-8

9 Tips ............................................................... 9-1

9.1 Tip View. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-49.2 Size Tip View. . . . . . . . . . . . . . . . . . . . . . . . . 9-329.3 Tip Summary View . . . . . . . . . . . . . . . . . . . . 9-34

10 Receptors ................................................... 10-1

10.1 Receptor Point View . . . . . . . . . . . . . . . . . . . 10-410.2 Receptor Point Summary View . . . . . . . . . . 10-1710.3 Receptor Grid View . . . . . . . . . . . . . . . . . . . 10-18

11 Shields........................................................ 11-1

11.1 Shield View . . . . . . . . . . . . . . . . . . . . . . . . . . 11-411.2 Rectangle Builder . . . . . . . . . . . . . . . . . . . . 11-1111.3 Polygon Builder . . . . . . . . . . . . . . . . . . . . . . 11-1311.4 Pit / Hut Builder . . . . . . . . . . . . . . . . . . . . . . 11-1511.5 Transform View . . . . . . . . . . . . . . . . . . . . . . 11-17

12 Dispersion .................................................. 12-1

12.1 Dispersion View. . . . . . . . . . . . . . . . . . . . . . . 12-412.2 Implementation Details . . . . . . . . . . . . . . . . 12-12

13 Overlays And Isopleths............................. 13-1

13.1 Overlay View . . . . . . . . . . . . . . . . . . . . . . . . . 13-413.2 Zoom View . . . . . . . . . . . . . . . . . . . . . . . . . 13-1513.3 Isopleth Customise View . . . . . . . . . . . . . . . 13-17

14 Calculations ............................................... 14-1

14.1 Calculation Options View . . . . . . . . . . . . . . . 14-3

15 Printing ....................................................... 15-1

15.1 Report View. . . . . . . . . . . . . . . . . . . . . . . . . . 15-415.2 Output Graphic Report View . . . . . . . . . . . . . 15-8

16 Calculation Methods ................................. 16-1

16.1 Thermal Radiation . . . . . . . . . . . . . . . . . . . . . 16-516.2 Surface Temperature. . . . . . . . . . . . . . . . . . 16-1616.3 Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-1716.4 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . 16-2416.5 Purge Gas . . . . . . . . . . . . . . . . . . . . . . . . . . 16-2616.6 Water Sprays. . . . . . . . . . . . . . . . . . . . . . . . 16-2916.7 References . . . . . . . . . . . . . . . . . . . . . . . . . 16-31

3

A Graphic Report Layout............................... A-1

A.1 Introduction to XML . . . . . . . . . . . . . . . . . . . . .A-4A.2 Layout File Structure . . . . . . . . . . . . . . . . . . . .A-6

4

Introduction 1-1

1-1

Page

1 Introduction

1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

1.2 Program Overview . . . . . . . . . . . . . . . . . . . .7

1.2.1 Flaresim Objects . . . . . . . . . . . . . . . . . . . . . 71.2.2 Object Definition . . . . . . . . . . . . . . . . . . . . . 91.2.3 Running a Model . . . . . . . . . . . . . . . . . . . . 10

1.3 Documentation Overview . . . . . . . . . . . . .12

1-2

1-2

Introduction 1-3

Flaresim is a computer program designed to assist professional engineers in the design and evaluation of flare systems. The program calculates the thermal radiation and noise generated by flares and estimates the temperatures of exposed surfaces. It also performs dispersion analysis of the combustion gases or relieved fluid in flame out conditions.

Flaresim provides a user friendly interface with program actions accessed by menu and toolbar options. Data entry is through a series of data views controlled from an overall Case Navigator view. Context sensitive help is available at all points to assist the user in the use of the program and selection of appropriate design parameters.

Output from the Flaresim is highly customisable with the user having the freedom to select summary or detailed output. The reports also include graphical output where appropriate.

Experienced flare system engineers should read the remainder of this chapter for an overview of the way that Flaresim performs calculations. They may then find that they will be able to use the program with assistance from the help system without further reference to the manual. However we would advise study of the manual to become familiar with the full range of options and recommendations for using the program.

Engineers new to flare system design should work through the examples in the Getting Started section of the manual after first reading this chapter. The examples provide a step by step guide to using Flaresim for flare system design and highlight some of the critical parameters that must be determined.

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1-4 Features

1.1 Features

The following features highlight the main capabilities of Flaresim.

• Equally applicable to the design of flare systems for offshore platforms, gas plants, refineries and chemical plants.

• Data may be entered and reported in the users choice of units and may be converted at any time.

• Correlations are available for modelling a range of flare tips including sonic tips, pipeflare tips and steam or air assisted tips. For assisted flares the quantity of steam or air required for smokeless operation can be calculated.

• A number of correlations are provided to predict the fraction of heat radiated from flames of a range of hydrocarbon fluids with different types of flare tip.

• Liquid flaring systems can be handled.

• A wide range of algorithms for calculation of thermal radiation. These include integrated multipoint methods and the Chamber-lain (Shell) method in addition to the Hajek/Ludwig and Brzustowski/Sommer methods which are described in the API guidelines for flare system design.

• Full three dimensional flame shape analysis with complete flexi-bility in specification of the location and orientation of multiple stacks.

• Calculation of combustion gas composition.

• Calculation of purge gas flows required for tips.

• Jet dispersion model to analyse flammable gas concentrations close to flare in flame out conditions.

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Introduction 1-5

• Gaussian dispersion model to analyse longer distance dispersion of the relieving fluid or combustion gases.

• A range of options for defining and analysing the noise spectrum generated by flare systems including user defined spectra.

• Ability to define multiple environmental scenarios to allow rapid evaluation of flare system performance under different wind speeds and directions.

• Multiple stacks/booms each accomodating multiple flare tips.

• Calculation of radiation, noise spectrum and surface tempera-tures at multiple receptor points.

• Calculation of radiation variation with wind direction and speed at a point and display of results on a wind rose chart.

• Ability to define multiple receptor grids in multiple planes for calculation of radiation, noise or surface temperatures.

• Plotting of grid results as isopleth contours for sterile area definition.

• Receptor point characteristics for calculating surface tempera-tures include mass, absorbtivity, emissivity, area, specific heat, orientation and initial temperature.

• Modelling of water curtains or solid shields to reduce radiation and noise transmission.

• Sizing of stack or boom length to meet radiation, noise or sur-face temperature limits at defined receptor points.

• A setup wizard to allow new users to set up an initial model rapidly with appropriate defaults.

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1-6 Features

• Expert mode to control access to less commonly used options.

• Import of files from Flaresim 2.0 and later.

• Multiple reports can be created and compared as updates are made to a model and the data corresponding to any report can be saved.

• Quality Assurance options are included in the reports.

• Customisable HTML reports

• Customisable graphic reports

• Multiple Flaresim cases can be open at the same time.

The wide range of calculation options available within Flaresim may lead to the possibility of selecting inappropriate correlations for a particular combination of fluid type and flare system configuration. While we have tried to prevent the use of the more obvious problems we have also tried to allow flexibility for “one off” situations. As with all engineering computer software, Flaresim is a tool which cannot replace sound engineering judgement.

Softbits Consultants Ltd are always interested in continuing product development to ensure that Flaresim meets the needs of our clients. Should you wish to see any feature incorporated in Flaresim, please feel free to contact us at [email protected]. If the request is reasonable we will endeavour to include it in future releases of the program.

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Introduction 1-7

1.2 Program Overview

The Flaresim program has been developed to provide great flexibility in modelling by breaking down the flare system into a number of objects such as fluids, stacks, tips etc. These individual objects are then linked together to define the complete system.

Flaresim provides a Case Navigator view, see Figure 1-1, that shows a tree structure of all the objects that have been defined in a given model and provides a rapid overview of which ones are currently complete and in use.

Figure 1-1, Case Summary viewCase Navigator Icons

Required object present and ready

Required object missing or not ready

Optional object

Permanent object

Object ready

Object not ready

Object ignored

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1-8 Program Overview

1.2.1 Flaresim Objects

The objects that can be defined are:-

Case SummaryEach model contains a single Case Summary object which defines descriptive information.

FluidsA model can contain multiple fluid objects. Each object describes the physical properties of a fluid to be flared such as density, lower heating value, lower explosive limit etc. Fluids may be defined either by entering bulk properties or by defining the composition of the fluid to allow calculation of its properties from pure component data. A single fluid can be flared through multiple tips.

EnvironmentsA model can contain multiple environment objects each of which describes a combination of wind speed, direction, humidity etc. The variation of wind speed with direction can also be defined to support wind rose calculations. Environment characteristics can also be defined for use in dispersion calculations. Only one environment object can be active for a set of calculations.

StacksMultiple stack objects can be defined which may be active or ignored in any set of calculations. Stack data includes length, location and orientation. Each stack may support multiple flare tips.

TipsMultiple tip objects can be defined and set active or ignored in a set of calculations. Tip data includes tip type and associated calculation methods, dimensions and stack location data and the flow and selection of the fluid being flared. Tip objects provide access to flame shape and other tip specific results such as combustion gas composition and purge gas requirements.

Receptor PointsMultiple receptor point objects can be defined and then set active or ignored in a set of calculations. Receptor point data includes

1-8

Introduction 1-9

location, characteristics for surface temperature calculation and constraints for sizing calculations. Receptor point objects provide access to results calculated for the point. The effect of wind speed and direction on the radiation can also be calculated and displayed as a wind rose plot.

Receptor GridsMultiple receptor grid objects can be defined and then activated or ignored in a set of calculations. Receptor grid data includes orientation, location and coarseness data as well as characteristics for surface temperature calculations. Receptor grid objects provide access to their calculated results including contour plots of radiation, noise, surface temperature and gas dispersion.

Assist FluidsMultiple assist fluid objects may be defined and selected for one or more flare tips. Data includes assist fluid type and calculation method to be used.

ShieldsMultiple shield objects may be defined to model the reduction in radiation and noise through the installation of water sprays and solid shields. The transmissivity of water sprays can be specified by the user or calculated using an internal correlation. Shields can also be defined to model burn pits or protective locations.

DispersionsMultiple dispersion objects may be defined to model the dispersion of combustion gases and flare fluids over long distances using a Gaussian dispersion model. Either concentration contour plots for a single pollutant or a downwind plot for multiple pollutants can be calculated.

OverlaysOverlay objects allow simple drawings to be created to act as background pictures for contour plots produced by the Receptor Grid and Dispersion objects.

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Calculation OptionsA single calculation options object defines the correlations to be used in the calculations. It also provides for control of stack sizing options, heat transfer options to be used for temperature calculations and default emissions data. A data fitting option is also available.

Component ManagementA component library manager object allows maintenance of the pure component database.

1.2.2 Object Definition

Flaresim objects are created by selecting the branch in the Case Navigator view and then clicking the Add button. Alternatively the Add dropdown menu in the Case Navigator can be used.

Creation of an object automatically opens its view to allow its data to be entered. When all the required data has been entered the status text at the bottom of the view will indicate Ready as shown in Figure 1-2.

Some objects have more data items than will fit on a single form so their views have been divided into multiple tabs.

For example the Tip view as shown in Figure 1-2 has tabs for Details, Noise Input, Location & Dimensions, Fluids, Emissions, Results, Noise Results, Flame Shape, Combustion Results and Purge Gas. Individual tabs are selected by clicking on their name.

Existing objects can be updated by double clicking them in the Case Navigator view or selecting them in the Case Navigator view and clicking the View button. When the Case Navigator is closed existing objects can be displayed by selecting them in the View dropdown menu.

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Introduction 1-11

1.2.3 Running a Model

In order to run calculations a Flaresim model must contain at least one of each of the following objects in an active and ready state.

• Fluid object• Environment object• Stack object• Tip object

While this is sufficient to perform calculations this will not calculate any radiation, noise or surface temperature results without addition of at least one active Receptor Point or Receptor Grid.

Calculations are started by clicking the button at the top of the Case Navigator. This button is also used to display the progress of

Figure 1-2, Tip View

1-11


calculations and the status of the model. When the Case Navigator is closed the icon can be clicked to run the model. Progress of calculations and any problems encountered are reported in the right hand Message window at the bottom of the Flaresim screen.

Results from the calculations may be viewed through the appropriate tabs in the Tip view, Receptor Point view or Receptor Grid view. Results may be viewed in tabular or graphical format where appropriate. Alternatively results can be viewed and printed through the Print or Print Graphic Report buttons in the Case Navigator tool bar.

Once complete a case can be saved using the Save and Save As buttons in the Case Navigator tool bar.

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Introduction 1-13

1.3 Documentation Overview

The printed Flaresim manual contains the following chapters:-

Chapter 2 - Software Installation and License Activation.

Chapter 3 - Tutorial with detailed worked examples.

The electronic documentation in the file Flaresim.pdf contains this material and the following additional chapters which provide a full detailed description of the program features.

Chapter 4 - Concepts, Flaresim Interface, Menu structure, Log Panels and File Dialogs.

Chapter 5 - General Setup including Case Navigator, Case Summary, Preferences and Component Management.

Chapter 6 - Fluid and Assist Fluid views.

Chapter 7 - Environment view.

Chapter 8 - Stack view.

Chapter 9 - Tip view.

Chapter 10 - Receptor Point and Receptor Grid views.

Chapter 11 - Shield view.

Chapter 12 - Dispersion view.

Chapter 13 - Overlay editor view.

Chapter 14 - Calculation Options view.

Chapter 15 - Report options including Print Reports and Graphic Reports.

Chapter 16 - Calculation methods.

Appendix A - Graphic Report Layout File Definition

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1-14 Documentation Overview

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Installation 2-1

2-1

Page

2 Installation

2.1 Installation Requirements . . . . . . . . . . . . . .3

2.1.1 Package Requirements . . . . . . . . . . . . . . . . 32.1.2 System Requirements . . . . . . . . . . . . . . . . . 3

2.2 Installing Flaresim-Single User. . . . . . . . . .4

2.2.1 Starting Flaresim Software Installation . . . 42.2.2 Installing .Net Framework . . . . . . . . . . . . . . 52.2.3 Running Flaresim Installation. . . . . . . . . . . 72.2.4 Installation of Sentinel Drivers . . . . . . . . . 132.2.5 Standalone License File Installation . . . . 172.2.6 Obtaining A License File . . . . . . . . . . . . . . 192.2.7 Troubleshooting Standalone Installation. 22

2.3 Installing Flaresim - Network . . . . . . . . . .25

2.3.1 Installing Server Software . . . . . . . . . . . . . 252.3.2 Installing Server License File . . . . . . . . . . 322.3.3 Troubleshooting License File Installation 362.3.4 Installing Flaresim Clients. . . . . . . . . . . . . 372.3.5 Trouble Shooting Flaresim Client. . . . . . . 38

2.4 Flaresim File Locations . . . . . . . . . . . . . . .40

2.4.1 Install Locations on Windows XP. . . . . . . 402.4.2 Install Locations on Windows Vista . . . . . 412.4.3 Install Locations on Windows 7 . . . . . . . . 41

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2-2

Installation 2-3

2.1 Installation Requirements

2.1.1 Package Requirements

Before installation, check that you have the following elements of the Flaresim package.

• Program CD Rom or Flaresim Download Package• USB Computer ID Key, (or legacy 25 pin parallel port key)• License File• Getting Started Guide

The License File will be sent to you separately by e-mail as an attachment. You should save the file to a temporary location so that it is ready when required by the installation process.

2.1.2 System Requirements

The following system requirements must be met to allow installation of Flaresim.

Item Requirement

Operating system Windows XP, Windows Vistaor Windows 7

Disk space - Flaresim program ~45 MB

Disk space - .Net framework ~290 MB

Disk space - Sample files (opt) ~2MB

Computer ID key device port USB port (opt 25pin parallel port)

Flaresim install files Supplied on CD Romor download package

Internet Access For 280 Mb download of .Net frame-work if not already installed and you

are using the Flaresim download package.

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2-4 Installing Flaresim-Single User

2.2 Installing Flaresim-Single User

The single user version is where usage of the program is controlled by a license file installed on the PC on which Flaresim is running.

The installation of Flaresim is a two step process. First the software must be installed. Then the license file must be installed to activate the software.

2.2.1 Starting Flaresim Software Installation

The installation of Flaresim is similar to the installation of other Windows programs. The steps are:-

1. Shut down other windows programs. The Windows Explorer program may be left open to start the Flaresim Setup program.

2. Either: Insert the Flaresim CD Rom into your CD or DVD drive.

If the AutoRun feature is enabled then step 3 will be per-formed automatically and should be skipped.

Or: Extract install files from download package to a tempo-rary location on your hard disk.

3. Either: Start the setup program Setup.exe on the CD Rom.

This may be done through Windows Explorer by navigating to your CD or DVD drive, locating the Setup.exe file in the root directory of the CD and then double-clicking it.

Alternatively you can click the Windows Start button, select the Run option, type d:\setup.exe in the pop-up dialog and then click the Ok button. Note that your CD or DVD drive letter should be substituted if it is not d:.

Or: Start the setup program Setup.exe in the temporary location to which you have extracted the installation files.

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Installation 2-5

This may be done through Windows Explorer by navigating to the temporaryfile location, locating the Setup.exe file and then double-clicking it.

Alternatively you can click the Windows Start button, select the Run option, type [location}\setup.exe in the pop-up dia-log and then click the Ok button. Note [location] is the tem-porary file location to which you extracted the installation files.

The installation program will begin.

2.2.2 Installing .Net Framework

Starting with Flaresim version 3.0 the Microsoft .Net Framework 3.5. is required to support Flaresim. The installation program first checks whether this set of support files is available. If it is then the installation process will automatically skip to step 7.

If you do not have the .Net Framework already installed on your computer the following screen will be displayed and you will be invited to install it. If you do not install it then the Flaresim installation program will close.

The details of the following screen will differ depending on whether you are installing from a CD or a download package. In the former case the .Net Framework 3.5 SP1 files are included on the CD and the screen will appear as shown. In the case of a download package the screen will indicate that the .Net Framework 3.5 SP1 will be installed through download from the web.

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4. Click the Install button to start the .Net Framework installation. If you are using a Flaresim download package and the Web Download installation of the .Net Framework be aware that this is a 280Mb download and can take an appreciable time to download and install.

5. Once the .Net Framework installation process has finished the following screen will be displayed. Click the Yes button to restart your computer and complete the installation of the .Net Framework.

6. Once your system has completed rebooting please restart the Flaresim Installer as described in section 2.2.1

Figure 2-1, .Net Framework Required

Figure 2-2, .Net Framework Installation Finished

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Installation 2-7

2.2.3 Running Flaresim Installation

7. After verifying the availability of the .Net Framework version 3.5 the Flaresim Installation wizard will start and after a configuration screen for the Windows Installer the follows screen will appear.

Click the Next button.

Note that the setup program provides a Cancel button that may be clicked to exit the installation procedure at any point.

8. The following License Agreement screen, Figure 2-4, should then appear..

Figure 2-3, Flaresim Installation Wizard Start

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9. At this point you should read the License Agreement and confirm your acceptance of its terms by clicking the accept option.

Once the accept option has been selected the Next button will be activated and should be clicked to continue the installation. The following screen, Figure 2-5, will appear.

If you do not wish to accept the license terms then click the Cancel button to exit the setup program without installing Flaresim. The license terms must be accepted before the program will install.

Figure 2-4, License Agreement

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Installation 2-9

10. If you are content with the proposed installation folder in your Program Files directory then click Next to continue.

Otherwise click the Browse button and use the standard windows file browser to select the destination folder for the Flaresim program. Once you are happy with your selection click Next to continue.

The installation type screen, Figure 2-6, will appear.

Figure 2-5, Destination Folder

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11. On this screen for a full installation select the Typical option and click Next.

The Custom option should be selected if you do not wish to install the Flaresim sample files.

The final install screen will appear..

Figure 2-6, Installation Type

Figure 2-7, Ready to Install Screen

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Installation 2-11

12. At this point Flaresim is ready to install. Click the Install button to start the installation process.

If you wish to change any data entered in an earlier screen the Back button may be used to return to earlier screens.

After clicking the Install button the installation will start.

13. The setup program will show the progress of the installation as files are copied from the CD Rom to your install folder as shown below.

Should you need to halt the installation, the Cancel button may be used to stop the installation. A confirmation dialog will ask you to confirm that you wish to exit without com-pleting the installation of the program.

14. Once the installation of the program files has been completed the Flaresim License Installer will be started to allow you to install a local license file.

Figure 2-8, Installation Progress

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If you do not have your license file or you expect to be using a network license click the Cancel button.

Otherwise click the Browse button to open a standard Win-dows file browser and select the Flaresim license file from the temporary location to which you have saved the license file sent you by email. Alternatively you can type the license file name into the field provided.

15. When you have entered the license file name, click the Install button. If the license file has been correctly installed the following message will be displayed. Click the Ok button to finish the license installation process and close the license installer.

If there is any error in installing the license file a pop-up message will describe the problem and you will be returned

Figure 2-9, Flaresim License Installer

Figure 2-10, Successfull License Installation

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Installation 2-13

to the main window of the Flaresim License Installer. If you have persistent problems then you can use the Cancel button to bypass license installation at this time and complete this later.

16. Following the closure of the Flaresim License Installer, the following screen will be shown. Click the Finish button to complete the installation process.

2.2.4 Installation of Sentinel Drivers

Following completion of the Flaresim installation process an installer for the Sentinel Drivers for use of the Computer ID key will appear as shown below,

The Sentinel Drivers are not required for using Flaresim through a network license or for a short term standalone license when the license will be locked to a specific PC hard disk. If this is the case click the Cancel button and skip to section 2.2.5..

Figure 2-11, Completion Screen

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17. Click the Next button to start the Sentinel software installation.

It is also possible that the Sentinel Protection software is already installed on your PC to support other applications for example, the Aspentech suite. If this is the case you may be offered an Upgrade button in place of the Next button. The Flaresim USB keys are compatible with any version of the Sentinel Protection Installer greater than 7.2.2 so if your current version is more recent you can use the Cancel button to exit without upgrading the Sentinel software.

18. A screen displaying the Sentinel Protection software license will then be displayed. This license must be accepted to allow the installation to procede. Click the Next button.

19. The next screen, Figure 2-13, allows you to select the installation type.

Figure 2-12, Sentinel Drivers Installation

2-14

Installation 2-15

For the Flaresim Computer ID keys you need only the driver software so you can select Custom option as shown and click Next to display the Installation Options selection screen shown below, Figure 2-14.

Figure 2-13, Sentinel Software Installation Type

Figure 2-14, Sentinel Software Installation Options

2-15


If you are doing an Upgrade installation you might wish to select the Complete option to ensure that all other Sentinel protected applications will have the required software installed. In this case clicking the Next button will skip to step 23.

20. In the Sentinel Software Installation Options screen, ensure that the Sentinel System Drivers are selected for installation as shown in Figure 2-14. The other features such as the Sentinel Protection Server can be set to “Do not install”.

Click Next to continue.

21. The next screen will indicate that the Sentinel Protection Installer is ready to begin. Click the Install button to start it.

22. Once complete the following view, Figure 2-15, will be displayed. Click the Finish button to complete.

23. At this point you are ready to install your Computer ID key.

If you have USB computer ID key then plug it into a free USB port on your computer. The first time this is done, you

Figure 2-15, Sentinel Protection Installer Complete

2-16

Installation 2-17

should expect to see confirmation that a Sentinel Ultrapro device has been detected and the driver installed.

If the key is a parallel port device with 25 pin connectors, plug it into the parallel port of your computer. The parallel port is the 25 pin female connector on the back of your com-puter. The arrows on the Computer ID key show which end connects to the computer. If you have a printer already con-nected to the parallel port, disconnect it, connect the key and then reconnect the printer to the female connector on the key. You will not see any messages from the driver soft-ware for this type of device.

24. Congratulations, Flaresim has been successfully installed. You are now ready to run the program for the first time by selecting it through the windows Start menu.

2.2.5 Standalone License File Installation

Flaresim requires installation of a license file before it will run. If a license file is not found when Flaresim starts, then an error message similar to that shown below in Figure 2-16 will be displayed. .

If you are installing a demonstration version of Flaresim or do not have a license file available at installation because this has been emailed separately then you will need to install the Flaresim license using this procedure.

If you do not have a license file see the instructions in the following section, 2.2.6, to obtain one.

Figure 2-16, Flaresim License Error

2-17


1. Firstly ensure that you have permission to write files in the Flaresim program folder - normally C:\Program Files\Flaresim 3.0. This may require Admin-strator or other privileges.

2. Start the Flaresim License Installer from the Flaresim 3.0 folder in the Start Programs menu. The Flaresim License Installer program will open and display the following view.

3. Click the Browse button to open a standard Windows file browser and select the Flaresim license file from either your Flaresim CD or any other location to which you have saved a license file. Alternatively you can type the license file name into the field provided.

4. When you have entered the license file name, click the Install button. If the license file has been correctly installed the following message will be displayed. Click the Ok

Figure 2-17, Flaresim License Installer

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Installation 2-19

button to finish the license installation process and close the license installer.

If there is any error in installing the license file a pop-up message will describe the problem and you will be returned to the main window of the Flaresim license installer. The most likely cause is that the installer does not have permis-sion to write the license file to the Flaresim program folder. If required you can use the Cancel button to close the Flaresim license installer without installing the license.

If you have problems during the license installation or Flaresim continues to generate error messages when you attempt to run it then make a note of any error message messages. You should then follow the troubleshooting guide in section 2.2.7 and/or contact [email protected] for assistance.

2.2.6 Obtaining A License File

If you have a fully licensed copy of Flaresim your license file will normally be emailed to you when you confirm receipt of your Flaresim package. If a license file was not emailed to you, you will need to supply some information about your installation to Softbits Consultants to allow a license file to be generated and emailed to you. The information required will depend on whether you have a full license for the program or a demo license.

Full License

If you have a full license for Flaresim you will have been supplied with a security key. The security key and its associated license file

Figure 2-18, Successfull License Installation

2-19


will allow Flaresim to be used by any PC as long as the security key is installed.

The procedure to obtain the license file is as follows:

1. Open the Windows Explorer program and browse to the Support sub-folder in the Flaresim program folder (usually C:\Program Files\Flaresim 3.0\Support).

2. Locate the program echoid.exe and double click it to run it. The program will check the security key and report the information required through a message window as shown below.

3. Report this information by e-mail to [email protected] together with your name and contact details. Your license file will be generated and returned to you by e-mail.

Short Term Lease or Demo License

If you have a short term lease or demo license for Flaresim you will not have a security key. A license file will be supplied to activate Flaresim for the single PC on which it is installed and for a limited period.

The procedure to obtain the license file is as follows:

1. Open the Windows Explorer program and browse to the Support sub-folder in the Flaresim program folder (usually C:\Program Files\Flaresim 3.0).

Figure 2-19, Security Key Information

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Installation 2-21

2. Locate the program wechoid.exe and double click it to start it. The program will start and display the screen shown below.

3. Clear all the Locking Criteria check boxes except that for Disk ID as shown above. Note the Locking Data displayed at the bottom of the screen. If the Locking Criteria check boxes have been set correctly, the Locking Data selector will be 0x4. Unless otherwise instructed ensure that the radio button at the bottom of the view is set to “New Style” to generate a long 16 character code.

4. Report the Locking Data by e-mail to [email protected] together with your name and contact details. Your license file will be generated and sent to you by e-mail. When you receive the license file use the procedure described in section 2.2.5 to install it.

Figure 2-20, Wechoid Program

2-21


2.2.7 Troubleshooting Standalone Installation

If an error message similar to Figure 2-16, is seen when starting Flaresim for the first time or an error message is seen when trying to add the Flaresim license then there are two possible causes.

• The Computer ID Key is not correctly installed• There is a Sentinel LM server in your network that is responding

to license requests and interfering with the operation of the local license for Flaresim. The Sentinel LM system is used by other products apart from Flaresim for example the Aspentech suite of software.

Checking Computer ID Key Installation.

The first of these problems can be tested for by running the program wechoid.exe which can be found in the support sub-folder of the Flaresim program folder (normally C:\Program Files\Flaresim 3.0).

Running this program should give an output similar to that shown in Figure 2-21. If the Computer ID entry is visible and holds a value then the security device is correctly installed

If the Computer ID section of the wechoid.exe output is greyed out or no data is shown then the security device is not correctly installed. A possible solution to this problem is to reinstall the Computer ID Key device drivers from the Drivers folder on the Flaresim CD. If the Computer ID key still cannot be seen by wechoid.exe even after reboot then the security device may be faulty and you should contact [email protected].

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Installation 2-23

Manual Installation of License File

If the license file cannot be installed by the FSWLicense Installer, it is possible to install the Flaresim license file manually as follows.

1. Open Windows Explorer, locate your license file (it will have a .LIC extension) and copy this to the Flaresim pro-gram folder (normally C:\Program Files\Flaresim 3.0.

2. In Windows Explorer, right click the license file in the Flaresim program folder and select the Rename option. Rename the file to “lservrc” note the quotes should be omitted and the file should have no file extension.

Forcing Flaresim to Use a Local License

If a Sentinel LM server is present in your network to support the use of other products e.g. the Aspentech suite of software then it is possible that it may be detected by Flaresim when starting and respond to license requests which then fail, preventing Flaresim

Figure 2-21, Wechoid.exe Output

2-23


from starting. In these circumstances Flaresim must be configured to force it to use a local license.

There are two methods of doing this:-

• Create a lshost file to help the Flaresim client locate the server. This is a simple text file called “lshost” containing the word “NO-NET”. A copy of this file can be found in the support sub-folder of your Flaresim program folder. To use it simply copy it to the Flareism program folder. Alternatively you can create the file lshost using a text editor. The file must not have a .txt exten-sion and must contain a single line with the word NO-NET.

• Set up an environment variable called either LSHOST or LSFORCEHOST and set this to the value NO-NET.

Note that environment variables LSHOST and LSFORCEHOST take precedence over the contents of an lshost file (if any). If an LSHOST or LSFORCEHOST environment variable has already been set up to support a different product then it will be necessary to start Flaresim from either a batch file or a script file that resets these variables to values appropriate to for the Flaresim server before starting Flaresim. Examples of both approaches can be found in the files Start Flaresim NoNet.bat and Flaresim NoNet.vbs in the Support sub-folder of the Flaresim program folder. These examples will require update to reflect the precise details of your installation if you have not used the standard installation folders..

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Installation 2-25

2.3 Installing Flaresim - Network

The network version of Flaresim allows the use of Flaresim from multiple client systems with the total number of copies in use being controlled by a central Flaresim license server.

Installing the Flaresim network version is a 3 step process. Firstly the server software must be installed. Then the license file must be added to the server. Finally the Flaresim client software must be installed on each machine that will run Flaresim.

Note the Flaresim license server is any PC on which the server software is installed. It does not have to be an existing network file server

IMPORTANT NOTE

If you already have a Sentinel LM server version 7.2 installed for a version of Flaresim prior to 2.1 it must be uninstalled and replaced with the new Sentinel RMS version 8 server that ships with Flaresim 3.0.

2.3.1 Installing Server Software

The Flaresim server software is the Sentinel RMS product from Safenet Inc. Full details of this product are given in the online manuals which can be found in the SysAdminHelp sub-folder of the Server folder of the Flaresim CD.

The following instructions are provided as a quick guide to installing your server software with a basic configuration. For more detailed information on the management of Sentinel RMS servers consult the online manuals.

The installation of the server software is similar to the installation of other Windows programs. The steps are:-

1. Shut down other windows programs. The Windows Explorer program may be left open to start the server setup program if required.

2-25

2-26 Installing Flaresim - Network

2. Insert the Flaresim CD Rom into your CD or DVD drive.

If the AutoRun feature is enabled then the screen shown below will appear inviting you to start a client installation. If this happens click the Cancel button to exit the client installation.

3. Open Windows Explorer, select the Flaresim install CD and browse to the folder \Server\Setup. Double click on the program Setup.exe to run it.

Alternatively you can click the Start button select Run and then type [Drive]:\Server\Setup\Setup.exe where [Drive] is the drive letter of your CD. Hit Enter to start the setup program.

On starting the server setup program the following screen will appear

Figure 2-22, Flaresim Client Screen

2-26

Installation 2-27

4. Click the Next button to continue. The following license agreement screen will be displayed

5. Click the appropriate radio button to accept the server software license agreement and click Next to continue. You must accept the license agreement in order to be able to run the Flaresim server software.

Figure 2-23, Server Setup Opening Screen

Figure 2-24, Server Setup License Agreement

2-27


The following screen will then appear.

6. This screen defines whether the software will be installed for all users of this computer or only the current user. Generally you will want to install it for all users. Once you have made your selection click Next to continue. The following screen will be shown.

Figure 2-25, User Selection

Figure 2-26, Server Software location

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Installation 2-29

7. This screen defines the location to which the server software will be installed, click Next to continue. The following screen will be displayed.

8. This screen allows selection of the Installation Options. Since Flaresim licenses are locked to Computer ID keys you must select the Complete option to install the device drivers for the keys as well as the server software. Click Next button to continue. The following view will be displayed.

Figure 2-27, Select Installation Options

2-29


9. A port must be opened through any server firewall to allow communication between the Flaresim server and client PCs. This screen allows you to tell the installer to do this automatically. Note that if you are using 3rd Party firewall software you may need to do this separately. The system administrators help system has the information you need to do this (Server\SysAdminHelp folder on CD).

Select the check box and click Next. The following screen will be displayed.

Figure 2-28, Firewall Settings

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Installation 2-31

10. This confirms that you are ready to begin installation of the Sentinel RMS server software. Click the Install button.

The server software install process will then start. On completion the following screen will be displayed.

Figure 2-29, Ready to Install

Figure 2-30, Server Installation Complete

2-31


11. At this point the server software is installed and the server service will have been started. Click the Finish button to close the window.

12. You may wish to confirm that the server service has installed correctly by checking the list of running processes through the Task Manager. The server service is called lservnt.exe.

By default, this service will be set to start automatically each time the computer is started.

13. Optionally copy the server utility programs to your server as follows.

Open Windows Explorer and browse to the directory [Drive]:\Server\Admin.net\W32 where [Drive] is the drive letter of your CD drive.

Select and copy all the files from this directory to an appropriate place on your server. It is up to your local policies whether to make these file available to Flaresim users as well as server administrators.

2.3.2 Installing Server License File

The Flaresim server software requires installation of a license file before it will be able to authorise Flaresim client software to run. This license file will normally be locked to the Computer ID key supplied with Flaresim.

The procedure to install the Computer ID key and license file is as follows. The license file will normally be found on the Flaresim CD.

1. Locate and install your Computer ID key on your server system.

If you have USB computer ID key then plug it into a free USB port on your computer.

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Installation 2-33

If the key is a parallel port device with 25 pin connectors, plug it into the parallel port of your server. The parallel port is the 25 pin female connector on the back of your compu-ter. The arrows on the Computer ID key show which end connects to the computer. If already have a printer on the parallel port, disconnect it, connect the key and then recon-nect the printer to the female connector on the key.

2. Open Windows Explorer and use it to browse to and start the program WlmAdmin.exe from either the Flaresim CD or the location to which you copied the server utility software. When open, the program will display the following screen.

Figure 2-31, WlmAdmin Program

2-33


3. Expand the tree of SubNet servers by clicking the symbol next to the SubNet servers entry. If your system is the only Sentinel server on the network then you will see only its name in the list. If other servers are present locate the server to which you have connected the Flaresim security device.

4. Right click the name of your server in the SubNet server list. From the pop-up menus select Add Feature, From a File, To Server and its File as the options appear as shown below.

Figure 2-32, WlmAdmin - Adding license

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Installation 2-35

5. Left click on the To Server and its File option. Select your license file (.lic extension) in the browser and click Open. Your license should be added to the server and displayed in the tree below the server name.

6. You will now be able to click the Flaresim license to display its details as shown below. Note that the WlmAdmin program can be used to show usage details of licenses at any time.

Figure 2-33, WlmAdmin License details

2-35


2.3.3 Troubleshooting License File Installation

Should you get an error message when installing the license file perhaps of the form shown below then the first thing to check is that the Computer ID key is plugged in and accessible.

This can be done by running the program wechoid.exe which can be found in the folder Server\Admin.net\W32 on your Flaresim CD.

Running this program should give an output similar to that shown below. If the Computer ID entry is visible and holds a value then the security device is correctly installed.

Figure 2-34, License Installation Error

Figure 2-35, Wechid.exe Output

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Installation 2-37

If the Computer ID section of the wechoid.exe output is greyed out or no data is shown then the security device is not correctly installed. A possible solution to this problem is to reinstall the security device drivers from the Drivers folder on the Flaresim CD. If the security device still cannot be seen by wechoid.exe even after reboot then the security device may be faulty and you should contact [email protected]

If the license file will not install when the wechoid.exe output shows that the security device is visible then there may be a problem with the license file and you should contact [email protected].

2.3.4 Installing Flaresim Clients

The installation of the Flaresim client software for use with a Flaresim license server is the same as for a standalone installation as described in sections 2.1.1 to 2.2.3 above.

Since there is no requirement for local license in a Flaresim network installation, when the FSWLicense installer is shown, step 14. , Figure 2-9, you should click the Cancel button.

Likewise since there is no need for a security key on a Flaresim client in a network installation you should click Cancel when the Sentinel Protection Installer view is displayed, step17., Figure 2-12.

You are now ready to run the Flaresim by selecting it through the windows Start menu.

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2.3.5 Trouble Shooting Flaresim Client

If the Flaresim client program fails to find a server license when it starts up the following message will be displayed.

If you see this message you should click the Ok button to close the window.

The following check list offers possible reasons why Flaresim might not be able to locate the license server to obtain a license.

• All available licenses are in use.• Client system does not have network access to the server.• Server may not be active.

Checking Available Licenses

The first step in resolving these problems is to run the WlmAdmin program from the client system and open the list of subnet servers.

If the Flaresim server can be seen, open the Flaresim license to check whether there is a license available. If all are in use the client must wait until a license becomes free. It can take up to 5 minutes for a license to become free after another user has shut down Flaresim.

Configuring Server Location

If an available license can be seen on the server but the Flaresim client still will not load then it may be caused by Flaresim being either unable to locate the Flaresim server or by Flaresim locating another Sentinel server for another product e.g. Aspentech products.

Figure 2-36, License Error

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Installation 2-39

In this case it is necessary to specify the name of the host to Flaresim. There are two options for this:-

• Create a lshost file to help the Flaresim client locate the server. To do this create a simple text file called lshost (note no .txt extension) in the Flaresim client program directory. Edit the con-tents of this file so that it contains the name of the Flaresim server. For example in the case of the server installation shown in section 2.3.2 of this file would have the text “orac.flaresim.co.uk”.

• Set up an environment variable called either LSHOST or LSFORCEHOST to specify the name of the server. For example in our example the environment variable would beset LSHOST=orac.flaresim.co.uk

Note that environment variables LSHOST and LSFORCEHOST take precedence over the contents of an lshost file (if any). If an LSHOST or LSFORCEHOST environment variable has already been set up to support a different product then it will be necessary to start Flaresim from either a batch file or a script file that resets these variables to values appropriate to for the Flaresim server before starting Flaresim. Examples of both approaches can be found in the files Start Flaresim.bat and Flaresim.vbs in the Support sub-folder of the Flaresim program folder. These examples will require update to reflect the precise details of your installation.

Checking Access To The Server

If the WlmAdmin program does not list a Flaresim server when run on the client then the problem likely lies in the client system not having network access to the server. You will need to check all elements of the network routing (e.g. firewalls, routers) to ensure that the server can be seen by the client system.

Further help on license server setup and possible problems can be found in the online manual in the SysAdminHelp folder on the Flaresim CD.

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2-40 Flaresim File Locations

2.4 Flaresim File Locations

A Flaresim client installation comprises a number of files split into the following groups.

Program Files Program - Flaresim.exeSupport libraries - various .dll filesLicense installer - FSWLicense.exeInstalled license file - lservrcHelp files - FSWHelp.chm, *.HLPDocumentation folder - Flaresim.pdf

Support Files Layout files - *.layDefault case file - Default.fswDefault report definition - Flaresim.xslUnits definitions - Units.xmlComponent database - LibraryComponents.xmlDefault preference file - Preferences.xmlDefault preferences file - PrintPreference.xmlReport logo file - Logo.gif

Sample Files Examples - *.fswReport sub-folders

2.4.1 Install Locations on Windows XP

The default install locations for the different groups of files when Flaresim is installed on Windows XP are as follows.

Program Files C:\Program Files\Flaresim 3.0Support Files C:\Documents and Settings\All Users\Application

Data\Softbits\Flaresim 3.0Sample Files [My Documents]\Softbits\Flaresim 3.0\Samples

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Installation 2-41

2.4.2 Install Locations on Windows Vista

The default install locations for the different groups of files when Flaresim is installed on Windows Vista are as follows.

Program Files C:\Program Files\Flaresim 3.0Support Files C:\ProgramData\Softbits\Flaresim 3.0Sample Files [My Documents]\Softbits\Flaresim 3.0\Samples

2.4.3 Install Locations on Windows 7

The default install locations for the different groups of files when Flaresim is installed on Windows 7 are as follows.

Program Files C:\Program Files\Flaresim 3.0Support Files C:\ProgramData\Softbits\Flaresim 3.0Sample Files [My Documents]\Softbits\Flaresim 3.0\Samples

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2-42 Flaresim File Locations

2-42

Getting Started 3-1

3 Getting Started

Page3.1 Simple Flare Stack Design . . . . . . . . . . . . .4

3.1.1 Objective and Data. . . . . . . . . . . . . . . . . . . . 43.1.2 Initial Setup. . . . . . . . . . . . . . . . . . . . . . . . . . 43.1.3 Initial Calculations . . . . . . . . . . . . . . . . . . . 133.1.4 Print Results . . . . . . . . . . . . . . . . . . . . . . . . 16

3.2 Sonic Tip Design . . . . . . . . . . . . . . . . . . . .18

3.2.1 Objective and Data. . . . . . . . . . . . . . . . . . . 183.2.2 Open Starting File . . . . . . . . . . . . . . . . . . . 183.2.3 Create Sonic Tip. . . . . . . . . . . . . . . . . . . . . 183.2.4 Run & Review Calculations. . . . . . . . . . . . 203.2.5 Compare Results . . . . . . . . . . . . . . . . . . . . 21

3.3 Two Tip Design. . . . . . . . . . . . . . . . . . . . . .23

3.3.1 Objective and Data. . . . . . . . . . . . . . . . . . . 233.3.2 Open Starting File . . . . . . . . . . . . . . . . . . . 233.3.3 Update Tip Data . . . . . . . . . . . . . . . . . . . . . 243.3.4 Run & Review Calculations. . . . . . . . . . . . 243.3.5 Update Pipe Tip . . . . . . . . . . . . . . . . . . . . . 25

3.4 Working With Isopleths . . . . . . . . . . . . . . .26

3.4.1 Open Starting File . . . . . . . . . . . . . . . . . . . 263.4.2 Adding a Flaresim Overlay . . . . . . . . . . . . 303.4.3 External Overlay File . . . . . . . . . . . . . . . . . 33

3.5 Welltest Burner Design . . . . . . . . . . . . . . .36

3-1

3-2

3-2

3.5.1 Objective and Data. . . . . . . . . . . . . . . . . . . .363.5.2 Open Starting File . . . . . . . . . . . . . . . . . . . .363.5.3 Add New Fluid Data . . . . . . . . . . . . . . . . . . .363.5.4 Add New Stack . . . . . . . . . . . . . . . . . . . . . . .373.5.5 Add Welltest Burner Tip . . . . . . . . . . . . . . .393.5.6 Add New Receptor Point . . . . . . . . . . . . . . .393.5.7 Run & Review Calculations. . . . . . . . . . . . .403.5.8 Add Water Screen . . . . . . . . . . . . . . . . . . . .413.5.9 Evaluate Rate of Temperature Rise . . . . . .443.5.10 Check Safety Case. . . . . . . . . . . . . . . . . . . .45

3.6 Gas Dispersion. . . . . . . . . . . . . . . . . . . . . . 47

3.6.1 Objective and Data. . . . . . . . . . . . . . . . . . . .473.6.2 Load or Create Base Case . . . . . . . . . . . . .483.6.3 Jet Dispersion Calculation . . . . . . . . . . . . .483.6.4 Gaussian Dispersion, Contour Plot . . . . . .513.6.5 Gaussian Dispersion, Downwind Plot . . . .533.6.6 Dispersion Analysis Comments . . . . . . . . .56

Getting Started 3-3

The purpose of this chapter is to provide an introduction to the use of Flaresim. The examples show how Flaresim may be used to calculate thermal radiation, noise and exposed surfaces temperatures arising from flaring at one or more flare stacks. Examples of dispersion calculations are also given. The examples begin with a simple flare stack design which is then refined and expanded. The examples attempt to highlight some of the critical parameters to be considered when designing a safe flare system.

The examples build up in stages. If you wish to skip a particular stage, the Samples sub-folder of the Flaresim program folder has model files saved at each stage.

3-3

3-4 Simple Flare Stack Design

3.1 Simple Flare Stack Design

3.1.1 Objective and Data

The objective is to design a flare stack for an offshore platform. It is assumed that an inclined flare boom will be used mounted on the side of the platform which faces the prevailing wind. The design is to be based on thermal radiation limits as follows:-

• 1,500 btu/hr/ft2 at the base of the flare stack.• 600 btu/hr/ft2 at the helideck located 150 ft from the side of the

platform and 30 ft above the base of the flare stack.

The following design data is available

FluidMaterial Hydrocarbon VapourFlow 100,000 lb/hrMol Wt. 46.1Vapour Temp. 300 FHeat of combustion 21,500 btu/lbHeat Capacity ratio 1.1

Tip Diameter 18 in

Wind Velocity 20 mph

3.1.2 Initial Setup

1. Start the Flaresim program through the windows Start button in the usual way.

2. We are going to build our first model through the Setup Wizard. For a new installation of Flaresim this will open automatically ready to build a new model. If this does not appear then you should select the File - Preferences menu option and select the “Use Setup Wizard for New Cases” check box on the Files&Options tab. Then select File - New

New File Icon

3-4

Getting Started 3-5

or the New File icon on the tool bar to create a new case with the Setup Wizard.

3. In the opening view of the Setup Wizard, set the unit set to Default Field as shown. Then click the Next button to move to the Fluid definition tab.

4. In the Fluid tab of the Setup Wizard enter the following data items, using the tab key or the mouse to move from field to field.

Temperature = 300 FMole Weight = 46.1LHV = 21500 btu/lbCp/Cv = 1.1

Note that some of these values (e.g Temperature or Cp/Cv) are originally displayed in purple colour denoting a default

Figure 3-1, Setup Wizard Opening View

3-5


value. When you entered a value the colour changes to blue denoting a user specified value.

The full list of colours used by Flaresim to display values is:-Purple for a fixed default valueRed for calculated default valuesBlue for a user specified valueGrey for a fixed, unchangeable input valueBlack for a calculated result

The remaining values for Ref Pressure, LEL and Saturation can be left at their default values. The finished view is shown below

Note that Flaresim requires the lower heating value for a fluid for its calculations. We are assuming that the value we

Figure 3-2, Setup Wizard Fluid Tab

LEL is used only by the Brzustowski flare radiation method.

3-6

Getting Started 3-7

have been given is the lower, net heating value rather than the higher, gross heating value.

Advice on the usage of each input value and the allowable input range is displayed in the advice panel as you move through the input fields.

When the entries are complete click the Next button.

5. In the Tip tab select the radio button to set the tip type to a Pipe Tip. In the table for selection of F Factor method select the check box to select the Generic Pipe method.

The F Factor, i.e. the fraction of heat radiated by the flame, is a critical design parameter for flare system design. The Generic Pipe correlation has been developed to predict F Factors across a range of exit velocities and fluid molecular weights and is generally recommended for initial calcula-tions. For final designs, we would always recommend con-sulting a flare system vendor for advice on the appropriate F Factor for a specific fluid and specific flare tip.

6. Still in the Tip tab, enter the Fluid Mass Flow Rate as 100,000 lb/hr. After this entry has been completed, the Tip Diameter field is updated to show the tip diameter required for the default Mach number of 0.45. In our case we know the tip diameter is 18 in so we update the calculated value to 18 in. The Mach number will be updated to 0.199 to indicate the velocity for the new diameter.

When complete the view should be as shown in Figure 3-3.

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Click the Next button to move to the next tab.

7. In the next tab, the Environment tab, enter the wind speed. Since the value we have been given is 20 mph we first click the entry displaying ft/s and select mph in the drop down menu before entering the value. If we wish to see the value in ft/s then click again in the units entry and select ft/s to display the converted value of 29.33 ft/s.

The remaining items can be left at their default values namely Wind Direction as 0 (i.e. North), Temperature 59 F, Humidity 10% and the User Transmissivity 1.0 with the Transmissivity Method set to “User specified”. Note this default transmissivity method with a specified transmissiv-ity value of 1.0 is the most conservative option.

Figure 3-3, Setup Wizard Tip Tab

The humidity value is only used when calculating the transmissivity.

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Getting Started 3-9

The final input is to remove the tick from the check box labelled “Include Solar Radiation” which means that the specified solar radiation value will NOT be added to the cal-culated value of flare radiation.

Including solar radiation leads to a more conservative design and its inclusion is recommended by API 521. How-ever some sources suggest it can be excluded. Solar radia-tion can have a significant impact on the flare design when low radiation values are considered. Since we considering a low design radiation for the Helideck in this case we will exclude solar radiation for this example.

The completed view is shown as Figure 3-4. Click the Next button to continue.

Figure 3-4, Setup Wizard Environment Tab

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8. In the Stack tab, select the radio button to set the Vertical Orientation to 60 degrees from horizontal. Then set the Stack Horizontal Orientation angle to 0 (i.e. North). The Stack Length will be left unspecified to let Flaresim calculate it.

The completed form is shown as Figure 3-5. Click the Next button to continue.

9. In the Receptors tab, click on the default receptor point “RP_1” and rename it to “Stack Base”. Set its Distance Downwind from Stack to 0 ft and confirm that the Allowable Radiation for the point is 1500 btu/hr/ft2.

Now click the Add button to create an additional receptor point for the radiation at the Helideck. Change the default name “RP_2” to “Helideck” and enter the location as North-

Figure 3-5, Setup Wizard Stack Tab

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Getting Started 3-11

ing -150ft, Easting 0ft, Elevation 30ft. and the radiation limit as 600 btu/hr/ft2.

The completed form is shown as Figure 3-6. Click the Next button to continue.

10. In the Calculations tab, select the check box to set the Calculation Method to Mixed and set the Flame Elements to 25.

As discussed in the Methods chapter, the Mixed method is a compromise designed to give the best accuracy for calculat-ing radiation both close to and further away from the flame. As such it is a good default method. 25 flame elements is usually sufficient to calculate the flame shape with a reason-able degree of accuracy.

Figure 3-6, Setup Wizard Receptors Tab

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The completed view is shown as Figure 3-7. At this points we have completed the Setup Wizard so click the Finish button.

11. When the Finish button is clicked, the Setup Wizard takes the data we have supplied and uses it to create the Flaresim objects that we need for our initial model. The Case Navigator view will be displayed to list all of these objects as shown in Figure 3-8. Note that the icon is shown against each object indicating it is ready to calculate and that the icon is shown against the key object branches to indicate that the model has the minimum information needed to run calculations.

Figure 3-7, Setup Wizard Calculations Tab

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At this point you can open each objects view by double clicking on them in the Case Navigator to see how the Setup Wizard has initialised the values.

12. This is a suitable point to save the data we have entered so

far. Click the tool bar button in the tool bar at the top of the Case Navigator or main tool bar. Since we have not yet saved the file, a File Save Dialog window will appear to allow us to specify the location and name of the file.

3.1.3 Initial Calculations

13. At this point we are ready to run the calculations by clicking the large button labelled “Click to Calculate” at the top of the Case Navigator. The button will change to show a progress bar as the calculation runs. Messages will be output to the Error/Warnings/Info log to show progress as shown below.

Figure 3-8, Case Summary

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Note that the scroll bars can be used to review earlier mes-sages. Also the log window can be resized by dragging the separator bar above it.

14. We can now review the results. Double click the Grid 1 item in the Case Summary view and then click the Radiation tab. Then select Plot in the Display drop down. The radiation isopleths are displayed as shown below.

Figure 3-9, Error/Warnings/Info log

Figure 3-10, Receptor Grid Isopleth Plot

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Click Stack 1 in the Case Navigator view and click the View button. The view will show that the stack length has been calculated as 247ft.

Finally open the Receptor summary view by double click-ing the “Receptor Point” branch label in the Case Navigator. As shown below, the Radiation Results line shows that our design radiation limit of 600 btu/h/ft2 has been met for the Helideck receptor while the radiation value at the Stack Base receptor is lower than its allowed value limit at 767 btu/hr/ft2.

15. This completes our initial design. Save the case.

Figure 3-11, Receptor Point Summary

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3.1.4 Print Results

16. Select the Print button in the Case Navigator tool bar. The Report Preview view shown below opens. Note that this will open in a new window, independent of the main Flaresim view.

17. Select the report elements you wish to see printed. To see what the report will look like with the current set of elements you will need to click the Refresh button to update it.

Figure 3-12, Report Preview

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In order to allow us to compare these results with future results you will need to ensure that the Stack Configuration, Tip Results - General and Flame Shape elements and the Receptor Point results are included. Once you have set your preferred report options you can click the Save Options but-ton to save your report options to a configuration file. Your chosen options will also be saved with the case.

18. When you are happy with the options you have chosen click the Print button to send the report to your default printer.

The standard Printer Dialog view shown below will appear to allow the printer and other options to be selected.

Figure 3-13, Printer Dialog

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3-18 Sonic Tip Design

3.2 Sonic Tip Design


The design that we produced in Example 1 meets our design radiation limits but requires a long 247ft stack. Since we are designing a flare stack for an offshore platform we wish to minimise the length and hence the weight of the flare stack as much as possible. Therefore we will attempt to reduce the required flare stack length by redesigning the system using a sonic flare tip.

The fluid data, environmental data and radiation limits are the same as for Example 1.

3.2.2 Open Starting File

1. If you are continuing from Example 1 you should save your

case before continuing using the button from the tool bar at the top of the Case Navigator. Skip to step 3.

2. Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples folder created by your Flaresim installation. This will usually be in the Softbits\Flaresim 3.0 folder in your configured “Documents” folder. Select the file “Example 1 - Result.fsw” and click the Open button.

3.2.3 Create Sonic Tip

3. Create a new tip by selecting the Tip branch in the Case Navigator view and then clicking the Add button or by selecting the Add - Tip drop down menu option.

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4. On the Details tab of the Tip view that opens enter the following data:

Name = “Sonic Tip”Tip Type = SonicNumber of Burners = 1 Seal Type = NoneFraction Heat Radiated Method = High Efficiency

5. On the Noise Input tab of the Tip view enter the following data:

Combustion Noise Method = Standard Reference.

6. Move to the Location & Dimensions tab and enter the following data:

On Stack = Stack_1Length = 3.0ftAngle to Horizontal = 90Angle to North = 0Exit Diameter = 18inRiser Diameter = 18inContraction Coefficient = 1.0 (default)Exit Loss Coefficient = 1.0 (default)Roughness = 9.843e-4in (default)Calc Burner Opening = Selected

7. Click on the Fluids tab and enter the following:

Fluid Name = Fluid 1Fluid Mass Flow = 100,000lb/hr

8. At this point the Status Text at the bottom of the Tip view should indicate that the tip data is complete. Close the view.

9. In the Case Navigator, select the branch labelled Tip 1 and then click the Ignore button. The icon beside the label should turn to a icon to confirm that the tip will not be included in the calculations.

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3.2.4 Run & Review Calculations

10. We are now ready to run the calculations. Click the large button at the top of the Case Navigator.

Once Flaresim has finished calculating, check the Errors/Warnings/Info log panel to confirm that the expected calcu-lations for the two Receptor Points have been completed. Note that if earlier messages in the log panel are causing confusion, you can click the right mouse button over the log panel to access a pop-up menu which provides a Clear option to remove the current log messages.

11. We are now ready to review the results. Open the Stack view for the Main Stack. The new length calculated for the stack is 68ft.

12. Open the Receptor Summary view. As shown below, this indicates that the Stack Base receptor point is now the controlling limit since the thermal radiation at this point is calculated as 1500 btu/hr/ft2. The radiation at the Helideck receptor point is 543 btu/hr/ft2.

Figure 3-14, Sonic Tip, Receptor Summary

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13. Save the new design to a new case name.

14. Generate a report for this new case using the Print tool bar button.

3.2.5 Compare Results

Our new design with the sonic flare tip is clearly better since it leads to a much shorter stack that will save a great amount of weight and hence cost over our initial design using the pipe flare tip. It is worth doing a detailed comparison to understand the difference between the designs.

15. Reopen the original case “Example 1 - Results.fsw” and click the Print tool bar button. Since reports are generated in separate windows then you will now have two report windows that you can compare side by side. Note that both cases are open simultaneously in Flaresim and you can switch between them using the Windows menu option.

Alternatively you can use your Internet browser to view the saved report files “Example 1 - Result.html” in the “Sam-ples\Example 1 - Result” sub-folder and “Example 2 - Result.html” in the “Samples\Example 2 - Result” sub-folder. (usually in [Documents]\Softbits\Flaresim 3.0).

16. Find the Tip Data - Results section in the reports. The fraction of heat radiated value for the Pipe flare design is 0.35 while that for the Sonic design is 0.1.

The fraction of heat radiated by a flare is a critical parame-ter in the design. Pipe flares exhibit relatively poor mixing of air with the flared fluid and as a result the flame contains many partially combusted luminescent carbon particles that give it an orange colour and a relatively high fraction of heat radiated. Sonic flare tips are designed to maximise the mixing of air and the flared fluid and so burn with a clearer flame with lower heat radiation.

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By selecting the appropriate F Factor method to calculate the fraction of heat radiated in both our designs we have allowed the program to calculate an appropriate value for the different tips. However since this is such an important factor in the design, the heat radiation factor to be used should be confirmed with your flare system vendor prior to the final design. Should you wish to use a heat radiation fac-tor supplied by a vendor you should set the method to User Specified and enter the value.

17. Still in the Tip Data - Results section of the reports find the flame length. For the Pipe flare design this is 173 ft. while for the Sonic flare design the flame length is 88ft. Note that the flame length calculated by the API method is the same in both cases.

Sonic flare tips by their design and by their greater gas exit velocities lead to a flame shape that is shorter and stiffer compared to that of a pipe flare. As a result the flame is less affected by wind and stays closer to the tip and thus further from the platform. This can be seen most clearly by compar-ing the 3D plot of the Flame Shape in the reports.

Finally in the Tip Results section of the reports find the tip back pressure i.e. tip inlet pressure. For the Pipe flare this is 14.7 psi while for the Sonic flare it is 26.0 psi.

The fact that the sonic tip is operating at choked conditions means that the pressure drop over this type of tip is much higher than for the pipe tip. Thus a sonic tip can only be used if the resulting back pressure on the flare system is not so high as to prevent safe relief of the gas.

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3.3 Two Tip Design

Comparison of our two designs using the pipe tip and the sonic tip shows that the sonic tip is much the better since it produces a shorter, stiffer and above all a flame with a lower F Factor than the pipe flare. This means that the flare stack can be much shorter while still meeting radiation limits. Given the advantages of the sonic tip it might appear that we should always specify this type of tip.

However we have also seen that the sonic flare tip results in higher back pressures on the flare system. In many cases this additional back pressure will be too high to allow safe relief from all the possible relief sources in the process. Therefore it is common to see designs with both high and low pressure flare systems relieving through different tips.


The relieving sources in our process have been reviewed to check that the new back pressure resulting from the sonic tip is acceptable. The review has shown that 10,000 lb/h of the material being flared cannot be relieved safely at the new higher back pressure. As a result we have decided to split our design so this 10,000 lb/h is relieved through a low pressure flare system leading to a pipe tip with the remaining material flowing through a high pressure flare system to a sonic tip.



case before continuing using the Save tool bar button in the Case Navigator. Skip to step 3.

2. Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples sub-folder of your Flaresim installation (usually [My Documents]\Softbits\Flaresim 3.0) and click the Open button.

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3-24 Two Tip Design

3.3.3 Update Tip Data

3. In the Case Navigator view double-click the Sonic Tip branch to open the view for this Tip. On the Fluids tab change the flow rate to 90,000 lb/h. Close the view.

4. Open the view for the Tip 1 by double-clicking this in the Case Navigator view or by selecting it and then clicking the View button. Rename the tip to “Pipe Tip”. On the Fluids tab change the flow rate to 10,000 lb/h. Then clear the tick from the Ignore check box to activate this tip again. Close the view.


5. We are now ready to run the calculations. Click the large button at the top of the Case Navigator.

Check the Errors/Warnings/Info log panel to confirm that the expected calculations for the two Receptor Points have been completed.

6. We are now ready to review the results. Open the Stack view for the Main Stack. The new length calculated for the stack is 96ft.

Figure 3-15, Stack View

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7. Open the Receptor Summary view. This indicates that the Main Stack receptor point is still the controlling limit since the thermal radiation at this point is still calculated as 1500 btu/hr/ft2.

3.3.5 Update Pipe Tip

In reducing the flow through the Pipe tip we have changed its performance.

8. Open the Tip view for the Pipe tip. You will see on the Details tab that the fraction of heat radiated from this tip has been calculated as 0.38 whereas before it was 0.35. The reason for this is the greatly reduced velocity, 0.02 mach, through the tip which reduces the tips efficiency. For efficient operation the velocity should be 0.2 mach or higher.

9. On the Location & Dimensions tab, click the Size Me button. Set the Mach number to 0.3 and set “Use Nominal Diam” to “No” and the tip size will be calculated as 4.6 in. Set “Use Nominal Diam” back to “Yes” and an nominal diameter of 5 inch will be selected. If you wish to check the actual Mach Number at the selected tip size, use the Nominal Diameter drop down list and reselect 5 inch to update the calculated Mach Number which will be 0.25 Mach. This is acceptable so click the Ok button. The tip size and riser diameter will automatically be updated to the new selected diameter.

10. Now recalculate the case. The new exit velocity is 0.25 mach and the fraction of heat radiated is now 0.34. The improvement in efficiency of this flare reduces the calculated size of the stack to 90ft.

11. Our two tip design is complete so save the case.

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3-26 Working With Isopleths

3.4 Working With Isopleths

To see details of the thermal radiation around the flare Flaresim provides the Receptor Grid objects that will calculate the radiation for a grid of points that can be used to generate isopleth charts showing lines of constant thermal radiation. Similar isopleth charts can be displayed for noise and surface temperature results.

Our model already has one receptor grid called Grid 1. This was automatically generated for us by the Setup Wizard. It shows a plan view around our flare stack at the grade elevation i.e. 0ft. Since the Helideck is the main area of interest we will update this grid to the correct elevation.



case before continuing using the icon from the Case Navigator tool bar. Skip to step 3.

2. Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples folder in your Flaresim installation ([Documents]\Softbits\Flaresim 3.0), select the file “Example 3 - Result.fsw” and click the Open button.

3. Since the Helideck is one of the main areas of interest, we will update the receptor grid to plot the radiation at this level. Open the Grid 1 object by double clicking on it in the Case Navigator. Once open, change the name to “Helideck Plan” and change the elevation offset to 30ft. Also update the number of points for each axis to 41.

Note that the number of points in the grid is not critical - a higher number will generate smoother, more accurate isop-leths at a cost of increased calculation time.

4. In the Case Navigator view select the Receptor Grid branch and click the Add button (alternatively select the Add -

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Receptor Grid drop down menu option) to create and open the view for a new Receptor Grid object.

5. Enter the following data to create a grid for the vertical cross-section through the axis of the flare.

Name = Helideck Elevation, Orientation = Elevation-Northing, Easting = 0ft, Elevation Min = -100ft, Elevation Max = 300ft, Elevation Points = 41, Northing Min = -500ft, Northing Max = 300ft, Northing Points = 41.

The receptor point properties are left at the default values.

6. Re-run the case. When the run is complete you will be able to inspect the isopleth plot by opening the grid view, clicking on the Radiation tab and then selecting Plot as the Display option. Similar plots for noise and surface temperatures can be found on the Noise and Temperature tabs.

7. You can customise the isopleth lines displayed on the plot by clicking the Customise button to open a plot properties view as shown below. Select the Contour Details tab and select the check boxes to show only the isopleth values for 600, 1500, 3000, 5000 and 10000 btu/hr/ft2 as shown in Figure 3-16 below. Note the colours of each isopleth can be customised by clicking on the line colour panel and selecting the colour from the pop-up colour picker dialog.

When your updates are complete you can click the button at the bottom of the Customise window to copy your changes to other isopleths of the same type.

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8. Isopleth plots will be included automatically as part of Flaresim standard reports. A plot may also be exported as a standalone graphics file clicking the Export button on an isopleth result tab when the display option is set to Plot. This displays a standard file save dialog which allows the type of graph to be exported to be selected from the Save as type drop down. Allowed types are JPG, BMP and PNG bitmap formats or WMF and EMF vector formats. Note vector format files are more suitable for re-scaling and inclusion in reports.

If the Export button is clicked while the isopleth results are displayed as a Table the save dialog will provide options to save the results table to a text file (of comma separated val-ues) or to an Excel spreadsheet file.

9. A graphical report that displays an isopleth plot together with a summary of the model data can be generated from the Graphical Report tab on the Receptor Grid view. Simply select the type of plot to be produced, the layout file and click the View Graphic Report button. A sample of the output produced is shown below. Note this is a modal

Figure 3-16, Isopleth Customisation

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window that must be closed before you can use other parts of Flaresim.

10. Graphic reports can be printed or exported as graphics files

using the Print Graphic Reports tool bar button . For example to export a graphic report of the radiation isopleth for the Helideck Plan view, select the Helideck Plan in the list of available receptors grids, select the check box for the radiation plot and JPEG Bitmap as the file type as shown below. Then click the Save Graphic Reports button. A browser window will open to allow the output folder to be specified. The graphic reports will then be automatically created and saved and the Log area of the Flaresim screen

Figure 3-17, Graphic Report View

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will list the output location of the saved files. Note the layout file used will be that specified on the Graphic Report tab for each receptor grid.

3.4.2 Adding a Flaresim Overlay

Flaresim allows drawings to be overlaid on isopleth plots. Drawings can either be imported or generated using the internal overlay editor. In this example we will create a simple plan view within Flaresim.

11. In the Case Navigator, select the Overlay branch and click the Add button. A new overlay object called Overlay 1 will be created and displayed. Change the name to “Helideck Plan”.

12. In the “Update Details From Grid” section of the Details tab, select the “Helideck Plan” grid and click Update. The Overlay dimensions are updated with those from the Helideck Plan Grid.

Figure 3-18, Output Graphic Report

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13. Select the Editor tab and click the zoom in and zoom

out buttons and/or resize the view until you can see the full drawing. Check the Show Stacks check box to display the location of the stack in the drawing to act as a guideline. Not this will not form part of the drawing.

14. Now click the Add Rectangle button and draw a rectangle to represent the platform outline from the top left corner at -200,0 to the bottom right corner 50,-200. This is done by moving to the first point using the displayed X,Y coordinates at the left of the view as a guide, clicking and holding the left mouse button then dragging to the second point.

15. Add a second rectangle to represent the helideck from the points -50,-100 to 30, -180.

16. Click the ellipse button and draw a circle within the helideck rectangle by moving to the point -50, -100, clicking and holding the left mouse button and dragging to the point 30, -180.

17. Click the text button and then click the drawing in the middle of the helideck circle. A vertical flashing bar will appear to indicate the text insertion point. Type the letter H and then hit the enter key to complete the text entry.

If the text is too small, click the select button and then select the text you have just entered. A set of selection points will appear around it to indicate that it has been selected. Now click the properties drop down menu and select the Text Font option to open a standard font dia-log to allow the text size and style to be defined. A size of around 24 pt is probably suitable.

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If required the selected text can also be moved by clicking and dragging with it the left mouse button - the yellow dot will indicate the point to click for dragging the text.

The overlay picture is now complete and should look some-thing like the view below.

18. Next open the “Helideck Plan” Receptor Grid and go to the Plot Overlay tab. Select the Use Flaresim Overlay radio button and then in the drop down menu that appears select the overlay we have just created, “Helideck Plan”. Finally tick the Show Overlay check box.

Now go to the radiation tab. The overlay is now displayed as the background picture to the isopleth as shown below.

Figure 3-19, Completed Overlay

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19. Save the case. The overlay file we have created will be automatically saved in the Flaresim case folder (i.e. the sub folder created with the same name as the Flaresim case which contains the report data) with the file extension “.fso”.

3.4.3 External Overlay File

The other method of displaying an overlay with your isopleth plots is to link to an external graphics file. The best type of background drawing to import is a scaled vector drawing i.e. a Windows metafile (.wmf) or enhanced metafile (.emf) but bitmap files (.bmp, .png and .jpg files) can also be used. Given that the locations of the stacks etc. in your Flaresim model are matched to the drawing on import the

Figure 3-20, Isopleth with Overlay

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isopleths will be correctly positioned in relation to the drawing. The following example shows how this is done.

20. Open the Plot Overlay tab in the Helideck Elevation Receptor Grid.

We know that the drawing we are going to import represents dimensions of 1050 ft wide by 750 ft high. The point corre-sponding to the base of the main stack (0,0) in the model is located at the point 500, 350 in the drawing.

21. Ensure the Details radio button is selected in the External File Details section and enter the following values:-

Elevation - Min = 0ft,Elevation - Max = 750ftNorthing - Min = 0ft Northing - Max = 1050ft.Location of Flaresim Origin - Elevation = 350ftLocation of Flaresim Origin - Northing = 500ft

22. Click the Browse button to import the background graphics file. The file to import is called elevation.wmf and is located in the Samples\example 4 - result folder. You will need to select “Windows Metafiles (.wmf)” in the “Files of Type” drop down in the File Open view to select this. Click Ok.

You can now click the Preview radio button to see the imported graphic file together with a blue outline rectangle which shows the extents of the current receptor grid on the drawing.

23. Reselect the Details radio button and set the Show Overlay check box. Move to the Radiation tab and you should see your overlay displayed on the isopleth as shown below.

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24. Our work enhancing the isopleth plots is now complete. Save the case.

Figure 3-21, External Overlay File

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3-36 Welltest Burner Design

3.5 Welltest Burner Design

Offshore platforms often include a facility for burning off liquids produced during well tests. Flaresim is capable of modelling this type of burner in addition to the conventional safety release flares.


A welltest burner capable of burning 30,000 lb/hr of liquid is to be added to our design. The properties of the liquid to be burned are as follows:

FluidMaterial Hydrocarbon LiquidFlow 30,000 lb/hrMol Wt. 52.9Vapour Temp. 100 FHeat of combustion 19,550 btu/lb

Tip Diameter 12 in



case before continuing using the icon from the Case Navigator tool bar. Skip to step 3.

2. Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples sub-folder in the Flaresim installation folder (usually [My Documents]\Softbits\Flaresim 3.0) select the file “Example 4 - Result.fsw” and click the Open button.

3.5.3 Add New Fluid Data

3. In the Case Navigator view select the Fluids branch and then click the Add button to create a new Fluid and open its view.

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4. Complete the view with the following entries;

Name = Welltest Liquid, Temperature = 100F, Ref Pressure = 14.7psiMole Weight = 52.9, LHV = 19,550 btu/lb, Cp/Cv = 1.2, LEL = 1.7%, Saturation = 100%.

The Critical Temperature and Critical Pressure fields can be left blank.

The completed view is shown below. Close the view when the data has been entered.

3.5.4 Add New Stack

5. In the Case Navigator view select the Stacks branch and then click the Add button to create a new Stack and open its view.

Figure 3-22, Welltest Fluid View

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6. Enter data for the new stack as follows, leaving other entries at their default values;

Name - Welltest Boom, LocationNorthing = -200ft, Easting = 0ft, Elevation = 0ft, Dimensions section Length = 55ft, Angle to Horizontal = 0 deg, Angle to North = 180 deg.

These entries define our new stack as a horizontal boom on the opposite side of the platform to our main flare stack.

The completed view is shown as Figure 3-23. Close the view when complete.

Figure 3-23, Welltest Boom View

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3.5.5 Add Welltest Burner Tip

7. In the Case Navigator, select the Tips branch and click the Add button to create and view a new Tip object.

8. On the Details tab of the Tip view enter the following data;

Name = Welltest Burner, Tip Type = Welltest, Number of Burners = 3, Fraction Heat Radiated Method = User SpecifiedSpecified Fraction Heat Radiated = 0.3All other values should be left at their defaults.

9. On the Location & Dimensions tab enter the following, leaving other values at their defaults;

On Stack = Welltest Boom, Length = 0ft, Angle to Horizontal = 0 deg, Angle from North = 180 deg. Exit Diameter = 12 in (Default)

Note the burner length and orientation fields serve to locate the precise location of the flame and the initial flame direc-tion. Even when the burner length is 0ft as here, the orienta-tion fields must still be entered.

10. On the Fluids tab select the Fluid as Welltest Liquid and enter the flow rate as 30,000 lb/hr. Close the view.

3.5.6 Add New Receptor Point

11. Add a new Receptor Point in the usual way. Define the following data to locate the receptor point at the base of the welltest burner boom;

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Name - Base Welltest Boom, Northing = -200ft, Easting = 0ft, Elevation = 0ft. All other fields may be left at their default values. Close the view.


12. In the Case Navigator view, select the Stack 1 object. Clear the Size This Stack check box. Now click the Ignore button. This will exclude the two tips on the main flare stack from the calculations.

13. Run the calculations by clicking the large button labelled “Click to Calculate”. Check in the Errors/Warnings/Info log panel that the case has run and calculated correctly.

14. Open the Receptor Summary view. The results, see Figure 3-24, show that the radiation limits for our original two critical locations that we have defined are met. The radiation at the base of the well test burner stack is 1406 btu/hr/ft2.

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15. Save the case.

3.5.8 Add Water Screen

The radiation calculated at the base of the welltest burner stack is acceptable for brief exposure only. Since more extended exposure might be required it is necessary to reduce the radiation. While this could be achieved by extending the length of the stack this would be an expensive option due to the added weight. It is normal to reduce radiation from welltest burners using water screens.

The effect of these can be modelled in Flaresim through the installation of shield objects

16. Add a Shield object either by clicking the Shield branch in the Case Navigator view and then the Add button or by using the Add - Shield menu option according to your preference.

Figure 3-24, Receptor Summary

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17. Enter data in the Details tab of the new Shield view as follows;

Name = Water Curtain, Radiation - Type = Water Screen Radiation - Layer Thickness Calculation = User Radiation - Layer Thickness = 0.5 inNoise - Transmissivity = 1.0 [default]

18. Select the Sections tab. The first section is already created for you. In the lower half of this view click the Add Vertex button 4 times to create a rectangular shield section with 4 corners or vertices.

19. Enter the following data;

Name - Water CurtainVertex 1 = Northing -205 ft, Easting, 50 ft, Elevation 40 ftVertex 2 = Northing -205 ft, Easting, 50 ft, Elevation -10 ftVertex 3 = Northing -205 ft, Easting, -50 ft, Elevation -10 ftVertex 4 = Northing -205 ft, Easting, -50 ft, Elevation 40 ft

Note it is a requirement when entering the locations of the vertices that each point is directly connected to the next point in the list as shown below. Flaresim will attempt to sort the points to meet this criteria if necessary.

Figure 3-25, Shield Section Input

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The completed form is shown below.

20. The Shield view should now show that the shield data setup is complete. Run the updated case and inspect the results.

The radiation value at the base of the welltest burner stack has been reduced to an acceptable value of 278 btu/hr/ft2. The radiation isopleth for the plan view clearly shows the effect of the shield, see Figure 3-27.

Save the case..

Figure 3-26, Complete Shield Section Editor

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3.5.9 Evaluate Rate of Temperature Rise

Since we are relying on the water screen to reduce thermal radiation in normal use, we should check the situation when the water screen fails. Given data on the receiving surface, Flaresim is able to calculate the rate of temperature rise.

21. Open the view for the Base Welltest Stack receptor point and select the Properties tab. Update the data as follows;

Emissivity = 0.7, Absorbtivity = 0.7, Area Ratio = 2.0, Mass = 10.4 lb/ft2, Mass Cp = 0.1075 btu/lb/ft, Initial Temperature = 60F.

Figure 3-27, Isopleth plot for Helideck Plan View

3-44


This data represents a steel plate, 0.25in thick. The Area Ratio of 2.0 indicates that one side of the plate is exposed to the flare radiation.

The On Plane value at its default value of None is a con-servative assumption that means that no credit will be taken for radiation striking the plate at an angle. Enabling this option to select the angle of the plate requires selection of the Export Mode option in the Calculation Options view.

22. Select the Water Curtain shield object in the Case Navigator and click the Ignore button. Then run the calculations.

23. In the Thermal Results tab of the Base Welltest Stack receptor point you can inspect the rate of temperature rise results in tabular or graphical form. The results show that the temperature will rise to 83F after 2 mins on its way to a final temperature of 122F.

Save the case.

3.5.10 Check Safety Case

The results with only the welltest burner in use show that the original design radiation limit for the helideck is met. However we still have to consider the situation when a safety release occurs while the welltest burner is in use.

24. Select the Main Stack, Stack 1 in the Case Navigator view and click the Activate button to restore it to the calculations.

You will probably find that the stack is not ready to run since its length was originally being calculated we have been running the case with the stack set to ignored. Set the stack length to 90ft, the value calculated in Example 3.

25. Click the Calculate button to run the model.

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Open the Receptor Point summary. The results show that the thermal radiation at the Helideck receptor is 1145 btu/hr/ft2, significantly exceeding our limit of 600 btu/hr/ft2.

At this point we might consider increasing the length of either the Main Stack or the Welltest Stack in order to ensure that the radiation limits are met again. However it may also be possible to consider the circumstances under which the welltest burners would be used at the same time as the main flare. Perhaps procedures could be established to prevent helicopter operations while the welltest burner was in use meaning that this higher radiation value is acceptable.

It is appropriate to emphasise at this point that Flaresim is a tool for analysing the performance of flare systems. It cannot replace the engineers judgement in selecting the appropriate conditions to model or determining whether a particular set of results represent an acceptable or a dangerous situation.

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3.6 Gas Dispersion

Flaresim includes two types of gas dispersion model intended for two different types of analysis

A jet dispersion calculation models dispersion of flared fluid close to the tip to identify the potential for dangerous gas concentrations in flame out conditions.

A Gaussian dispersion calculation models dispersion of flared fluid or combustion products over longer distances.

The aim of this section is to illustrate how to use each of these models.


A new case with the following data will be used.

Flared Fluid

Methane 0.9 mole fracEthane 0.08 mole fracH2S 0.02 mole fracTemperature 75 CRef Pressure 1.013 bar aFlow 50000 kg/hr

Mechanical Data

Tip diameter 387.4mm (16in)Tip length 1mStack location At origin, 0, 0, 0Stack length 20mStack orientation Vertical

Environment Data

Temperature 15 CWind 10 m/s from North

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3-48 Gas Dispersion

Our objective will be to analyse the gas dispersion around the flare in normal operation and flame out conditions.

3.6.2 Load or Create Base Case

1. If you wish to build the case from scratch then either select the File - New menu option or click the icon in the tool bar. The Setup Wizard will appear.

Select the European units set on the opening page for easy of entering the remaining data. Work through the Fluid, Tip, Environment and Stack tabs entering the data defined above. Once you have entered the Stack data you can click the Finish button to accept the default data for Receptors and Calculation options. Skip to step 3.

2. Otherwise use the File - Open menu option or the icon. In the File Open dialog that appears, browse to the Samples sub-folder in the Flaresim installation folder (usually [My Documents]\Softbits\Flaresim 3.0) select the file “Example 6 - Starter.fsw” and click the Open button.

3.6.3 Jet Dispersion Calculation

In this exercise we run a jet dispersion study to study the flammable gas concentrations around the flare in the event of a flame out.

3. Before enabling the jet dispersion calculations we will create a new Receptor Grid to see the results more clearly. Select the Receptor Grid branch in the Case Navigator and click the Add button. In the new view enter the following data.

Name = ElevationGrid Plane = Elevation-NorthingGrid Offset = 0mElevation Minimum = -100mElevation Maximum = 300m

3-48


Northing Minimum = -300mNorthing Maximum = 100mLeave remaining values at defaults.

4. Open the Calculation Options view by selecting it in the Case Navigator and clicking the view button. Select the check box labelled Jet Dispersion in the Include Options section of the General Tab.

Click the Calculate button

5. Return to the view for your Elevation receptor grid and select the Concentrations tab. You should see a result that looks something like that shown below.

The jet dispersion calculation shows the concentrations of the flare fluid in the event of a flame out and is useful for

Figure 3-28, Jet Dispersion Initial Result

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3-50 Gas Dispersion

establishing the regions in which a flammable gas concen-tration may be obtained.

At first sight the result above looks unrealistic since the concentration isopleths do not appear connected to the flare tip. This is a function of the limited number of points calcu-lated in the default grid.

6. In your Elevation grid view, go back to the Extent tab and increase the number of calculated points for both Elevation and Northing dimensions to 51. Click the Calculate button again.

Return to the Concentrations tab and you should see the fol-lowing, more accurate result.

Save the case.

Figure 3-29, Final Jet Dispersion Result

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3.6.4 Gaussian Dispersion, Contour Plot

In this exercise we will study the dispersion of H2S from the flare tip in the event of a flame out.

7. Create a Dispersion Object by selecting the Dispersion branch in the Case Navigator and clicking the Add button. In the Dispersion view enter the following data on the Input Data tab as shown below.

Name = H2S ContourPollutant Source = Flared FluidCalculation Type = Contour PlotContours Height = 0mNorthing Minimum = -1000mNorthing Maximum = 0mEasting Minimum = -500mEasting Maximum = 500mNumber of points, Northing and Easting = 41

Figure 3-30, Gaussian Dispersion Input Tab

3-51

3-52 Gas Dispersion

8. On the Pollutant Data tab select the H2S component only. For a contour plot, only one component can be selected.

Click the Calculate button

9. Select the Results tab and then the Plot option for the display. The plot shows the ground level concentration contours for H2S downwind of the stack as shown below

10. The results shown have been calculated at the default environmental conditions with atmospheric stability characterised as Class D with dispersion coefficients applicable to Rural terrain around the flare. Open the Environment view at the Dispersion Data tab and test the effect on the dispersion results as you change the Atm. Stability class from A (most turbulent) to F (most stable) and the effect of changing the terrain from Rural to Urban.

Figure 3-31, H2S Contour Plot

3-52


You will see that the H2S concentrations are higher closer to the flare when atmosphere is more turbulent and when urban terrain classification is used. The sensitivity of the results to these parameters shows the necessity of selecting the appropriate environment settings for your particular flare location.

3.6.5 Gaussian Dispersion, Downwind Plot

In this exercise we will consider the downwind concentrations of pollutants in the combustion gases of the flare when it is operating.

11. In the Case Navigator select the Dispersion branch and click Add to create a new dispersion object. In the Input Data tab of its view enter the following data.

Name = Combustion EmissionsPollutant Source = Combustion GasCalculation Type = Downwind Line PlotLine through Point = OriginHeight for Calculation = 0mDownwind Distance Minimum = 0mDownwind Distance Maximum = 10000mNumber of points = 41

12. Select the Pollutant tab. Select the SO2, NO, CO and Methane pollutants for calculation by checking the box alongside these components.

Some of the components in this list, the CO2, H2O, SO2 are calculated directly from combustion of the components in the flared gas. The Fluid view, Combustion Results tab shows the stoichiometric fraction of each of these compo-nents generated by combustion of the flared gas.

The remaining components, NOx (assumed as NO), CO and unburnt hydrocarbon (assumed as CH4) are calculated as typical emissions resulting from hydrocarbon combustion. The quantities of each component generated is calculated by

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3-54 Gas Dispersion

default using the global basis defined on the Calculation Option view Emissions tab. Alternatively in Expert Mode the emissions basis for each Tip can be specified on the Emissions tab of the Tip view.

The quantities of each component in the combustion gases for each Tip are displayed on the Combustion Results tab of the Tip view.

13. Since the dispersion of the combustion gases will be dependent on the flame temperature we will now set this. Open the Tip View and select the Fluids tab. At the bottom of this view you may input a value for the flame temperature or clear the specified value to allow it to be calculated from the specified combustion air ratio.

Set the Combustion Air ratio to 3.0 and clear the specified flame temperature.

14. Open the Environment view and set the Atm. Stability Class to PasquillB.

Click the Calculate button.

15. Return to the Combustion Gas Results tab of the Tip view to see the calculated flame temperature of 721 C and the combustion gas compositions.

In the Combustion Gas dispersion view go to the results page and select the plot result to view the results as shown below. The peak concentration of SO2 is calculated at 68 µg/m3 at a distance of approximately 1500m downwind of the flare tip.

3-54


16. As in the previous example, open the Environment view to the Dispersion Data tab and test the effect of changing the Atm. Stability Class and Terrain class settings. You will find that for stable atmospheric conditions, stability classes E, F that the emission concentrations are still rising at the maximum downwind distance we have defined (10,000m).

If you wish you can increase the maximum downwind dis-tance on the Input Data tab to calculate the results further downwind.

Figure 3-32, Combustion Gas Dispersion Downwind Plot Results

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3-56 Gas Dispersion

3.6.6 Dispersion Analysis Comments

It is worth making the following general comments on the dispersion analysis capabilities of Flaresim.

The jet dispersion analysis for flammable gas concentrations is based on the Cleaver & Edwards jet dispersion model which is regarded as a reasonable model for concentrations close to the source. However it does assume dispersion in “free air” and does not consider the effect of structures which might modify dispersion patterns and lead to higher concentrations of flammable gas than predicted by Flaresim. A more detailed analysis with specialised software would be required in these situations.

The Gaussian dispersion calculations for combustion gases and flared fluid over longer distances is a simpler theoretical model that does not include detailed terrain effects. As such it should be considered as suitable for screening calculations to indicate a possible need for more detailed analysis. Chapter 12 has additional comments on the implementation of the Gaussian dispersion model in Flaresim.

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Interface 4-1

4-1

Page

4 Interface

4.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . .3

4.2 Menu Bar. . . . . . . . . . . . . . . . . . . . . . . . . . . .7

4.3 Multiple Case Views. . . . . . . . . . . . . . . . . .10

4.4 Tool Bars. . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.4.1 Main Window Tool Bar. . . . . . . . . . . . . . . . .114.4.2 Case View Tool Bar . . . . . . . . . . . . . . . . . . 12

4.5 Log Panels . . . . . . . . . . . . . . . . . . . . . . . . .14

4.6 File Dialogs . . . . . . . . . . . . . . . . . . . . . . . . .15

4.6.1 File Save Dialog . . . . . . . . . . . . . . . . . . . . . 154.6.2 File Open Dialog. . . . . . . . . . . . . . . . . . . . . 174.6.3 Recent Files Menu . . . . . . . . . . . . . . . . . . . 184.6.4 Update Messages During File Open. . . . . 19

4.7 About View . . . . . . . . . . . . . . . . . . . . . . . . .20

4-2

4-2

Interface 4-3

Popup menu

The Flaresim interface has been designed to give you a great deal of flexibility in the way in which you enter, modify and view the data and results which comprise your flare models. This chapter describes the various components of the Flaresim interface. If you need help with any particular task, the on-line help can give you step-by-step instructions.

4.1 Terminology

The following view of the Flaresim screen shows most of the interface components that you will encounter.

Figure 4-1, Flaresim Screen

Tool bars

Active button

Check box

Menu bar

Status text

Object Views

Greyed button Tabs

Value withUnits

Radio button

FileManagementLog

MultipleCaseViews

CaseNavigator

Error /WarningLog

Input Tables

Drop downList

4-3

4-4 Terminology

Menu BarThe menu bar provides access to various program functions that are not specific to a particular Case. The options are described in more detail in section 4.2.

Tool BarsThe tool bar is a row of icons that provide quick access to the more commonly used program functions. Flaresim has one tool bar for the main program and each Case has a tool bar with options specific to it in the Case Navigator. The options are described in more detail in section 4.4.

Multiple Case ViewsFlaresim 3.0 allows multiple individual cases to be open at once for easier comparison and switching between different models. The multiple case views are managed using standard Windows conventions. Case Views may be expanded to full screen if required.

Case NavigatorThe Case Navigator provides a summary view of all of the objects in a Flaresim Case displayed in a tree structure. It also provides a local tool bar of program options that are specific to the case as well as buttons to access various program functions such as adding, deleting, copying, viewing, activating and ignoring objects as well as starting calculations.

Active ButtonButtons appear on most forms and may be clicked with the left mouse button to perform the action indicated. Active buttons are those where the label type is black.

Greyed ButtonButtons which have an action that cannot be performed at a particular time are displayed with the label type in grey.

File Management LogThis area of the Case View displays a record of file saving and retrieval activity. See section 4.5 for more information.

Throughout the manual, Clicking a button or other item means using the Left mouse button unless stated otherwise.

4-4

Interface 4-5

Errors / Warnings / Info LogThis area of the screen displays a record of error messages, warning messages and other information generated by Flaresim calculations. See section 4.5 for more information.

PopUp MenuPopUp menus are used to display additional choices in response to clicking buttons or clicking the right mouse button.

ViewThis is the term used to describe a window containing a group of data entry fields for a specific element of the program. Views in Flaresim are generally non-modal which means that multiple views can be open and used at the same time.

Views may be resized, minimised, maximised and moved within the Flaresim Case View in the same way as standard windows.

Status TextMany views have a status field at the bottom to indicate whether all the necessary entries have been made. The background to this text indicates the status, green indicates ready to calculate, red indicates missing data, yellow indicates that the object is ignored.

TabsSome views have more data entry items than will fit on a typical size window. Tabs are a way of subdividing the entries into groups within the view. Clicking a tab heading displays the group.

Input TablesThe majority of data for Flaresim cases is entered through Input Tables. These group together related items which may either be values with associated units, drop down selection menus, check boxes or simple text. Generally the values entered will be checked for validity on leaving each cell in the Table.

Value With UnitsInput items with associated engineering units are entered through a pair of Input Table cells, the first defining the unit, the second the value.

4-5

4-6 Terminology

The units initially displayed by an Input Table are the default units defined through the Preferences View, see section 5.4. The current units for an individual value can be reselected at any time to display the value converted to that unit. The current displayed unit will be used to convert any number input to the internal units used by Flaresim. When an Input Table is completely refreshed e.g. following a calculation, the default units will be displayed again. This allows values to be entered in a mixture of units.

For example in a field expecting a wind speed value when the default unit display is ft/s you can enter a value of “20 mph” by first changing the displayed unit to “mph” and then entering the value of 20. The displayed unit will be reset to “ft/s” and the converted value of 29.33 ft/s will be displayed when the Input Table is next refreshed.

Drop Down List BoxThis type of edit box provides a downward pointing arrow to the right which may be clicked to allow a choice to be made from a set of options.

Check BoxA check box is used to select options that can be either on or off. Clicking a check box once will display a tick in the box indicating that the option is on, also known as setting the check box. Clicking the box again will clear the tick indicating that the option is off.

Radio ButtonsRadio buttons are used to select one option from a group of mutually exclusive options. Clicking one radio button in a group will select that option and automatically deselect all the other options.

Scroll BarsWhere a list or a view is not large enough to display all the items required scroll bars will appear. The up and down arrows may be clicked to move through the view to display all the items.

4-6

Interface 4-7

4.2 Menu Bar

The Menu Bar provides access to the Flaresim program actions. The row of main menu items at the top of the main Flaresim window provides access to drop down menus as shown in Figure 4-2.

Main menu items are selected by clicking on them or by holding down the Alt key and first letter of the menu name. Once the sub- menu has opened the sub-menu items can be selected by clicking them or by using the up and down arrow keys and then hitting enter.

Menu items may also have a shortcut key combination displayed against them which can be used to select the action without using the menu.

Flaresim provides the following menu items.

Figure 4-2, Menu Bar

4-7

4-8 Menu Bar

Main Menu Sub Menu Description

File New Creates a new Flaresim case

Open Loads a Flaresim case from disk

Save Save current selected case

Save As Open save file dialog to save current selected case with a new name.

Save All Saves all open cases to disk

Print Create report for current selected case

Print Graphic Report

Open graphic report view for current selected case.

Preferences Opens the Preferences view

Exit Quits the Flaresim program

Recent files List of recently opened files that can be reo-pened directly by selecting the name.

Windows NewWindow

Creates a new Flaresim case

Cascade Organises the open case views into a cascade of overlapped windows

Tile Vertical Organises the open case views into a set of side by side windows

TileHorizontal

Organises the open case views into a set of stacked windows

Close All Close all case views

Arrange Icons

Organises icons for minimised case icons

Open Windows

List of currently open case views

4-8

Interface 4-9

Help Contents Opens Flaresim help file at contents page

Index Opens Flaresim help file at index

Search Opens Flaresim help file in search mode

About Version information about Flaresim

Main Menu Sub Menu Description

4-9

4-10 Multiple Case Views

4.3 Multiple Case Views

Flaresim 3.0 allows multiple cases to be open at once. Each case will have its own view window that will be contained within the main Flaresim window. A new case can be created at any time using the File - New menu item or by clicking the tool bar button. A an existing case opened by using the File - Open menu item or clicking the tool bar button.

Once open an individual Case View can be minimised, maximised or closed using the standard set of window control buttons display in the top right of the window.

Clicking the button of this set minimises the case view to just an icon at the bottom of the Flaresim view. In the icon view the left button changes to and clicking this restores the case view to its previous size. Clicking the button maximises the case view to the full size of the Flaresim window, covering any other case views that might be open. Again the button will be replaced by a button and clicking this will restore the standard window size. Finally the button will close the case.

The Preferences view, Files and Options tab includes an option which controls whether new cases and freshly opened cases are automatically display at the maximised size.

The Windows menu (see above) provides a list of the currently open cases and allows rapid switching between them. It also provides options for arranging the case view windows on the screen.

4-10

Interface 4-11

4.4 Tool Bars

A Tool Bar provides a row of icons that may be clicked to provide rapid access to some commonly used actions. Flaresim has tool bars in both the main Flaresim window and the Case Views.

4.4.1 Main Window Tool Bar

Flaresim provides the following options on the main window Tool Bar.

This icon creates a new Flaresim case.

This icon retrieves a Flaresim case from disk.

This icon saves the current selected case. If the case has an name and has already been saved it will be overwritten. If it is a new case a File - Save As dialog will open. A message indicating success or failure will be written to the File Management Log.

This icon saves the current selected case with a new name. A File - Save As dialog will open to allow the file name to be specified. A message indicating success or failure will be written to the File Management Log.

This icon saves all open Flaresim cases to the disk.

This icon opens the Report View for the current selected case and to allow printing of the case.

This icon opens the Print Graphic Report View to allows selection, saving or printing of the graphic reports for the current selected case.

This icon opens the Preferences view.

4-11

4-12 Tool Bars

4.4.2 Case View Tool Bar

Flaresim provides the following options on the Case View tool bar at the top of the Case Navigator.

This large button starts the calculations for the case. Once started, the button displays a progress bar for the calculations. On completion the background colour shows the status of the calculation results, green for success, red for failure. A pale orange background indicates that data has changed since the last calculation.

This icon opens a drop down menu offering a list of objects that can be added to the case. It is equivalent to selecting the object type branch in the Navigator tree view and clicking the Add button.

This icon saves the case. If the case has an name and has already been saved it will be overwritten. If it is a new case a File - Save As dialog will open. A message indicating success or failure will be written to the File Management Log.

This icon saves the case with a new name. A File - Save As dialog will open to allow the file name to be specified. A message indicating success or failure will be written to the File Management Log.

This icon opens the Report View to allow selection of the print options for the case and to allow printing of the case.

This icon opens the Print Graphic Report View to allows selection, saving or printing of the graphic reports for the case.

This icon collapses the Case Navigator into a summary view that consists of a vertical tool bar.

4-12

Interface 4-13

Vertical tool bar buttons in the Case Navigator summary are the same as in the standard Case Navigator with the following additions.

This icon expands the Case Navigator to its normal size.

This icon starts the calculations for the case. The colour of the tool bar background indicates the case status, green for calculated with results available and pale orange for not calculated.

This icon displays a pop up menu of the objects in the current case. Selecting an object will display its view.

4-13

4-14 Log Panels

4.5 Log Panels

The log panels at the bottom of the Flaresim main window are used to output messages from the program. There are two panels.

The left panel is known as the File Management Log and records details of file creation, file retrieval and file saving actions.

The right panel is known as the Errors/Warnings/Info Log and records messages generated by Flaresim as it calculates.

The size of the log panels can be set by moving the cursor to the top boundary of the panels or the boundary between the panels. At the point where the cursor changes to a pair of resizing arrows, the left mouse button may be clicked and dragged to resize the panel.

Both panels provide a popup menu with local options that can be opened by clicking the right mouse button. The popup menu provides the following options:

Clear - clears all messages from the log.

Save Messages - displays a standard file dialog to allow the current message list to be saved to an external log file.

Figure 4-3, Log Panels

4-14

Interface 4-15

4.6 File Dialogs

Flaresim uses standard Windows file dialogs to save and retrieve files.

4.6.1 File Save Dialog

The File Save Dialog appears when you select the File - Save As menu item or the File - Save menu item or Save tool bar icon for an unnamed case. The dialog also appears when you click the Export button or Save button on other Flaresim views e.g. to export results data from Receptor Grid views.

The main elements on this Dialog are:

FilenameCombo boxAllows you to enter the name of the file to save the Flaresim model to. As you type the name, the drop down list element of the combo

Figure 4-4, File Save Dialog

4-15

4-16 File Dialogs

box allows you to select an existing file that matches the name to overwrite if you wish.

The file name entered will be given the extension type specified in the Save As Type field unless you enter a different file extension.

Save As TypeDrop down List of allowed file typesAllows you to select the required file type.

Save InDrop down List of available storage locationsAllows you to select from the list of available storage locations configured for your computer system.

File ListList BoxShows the files and folders in the current folder. The list may be used to navigate the folder tree or to select files.

Folders can be opened and made the new current folder by double clicking on them. You can move up the folder tree by clicking the Previous Folder icon. New folders can be created by clicking the New Folder icon and entering the new folder name in the File List.

File Description Allowed Types

Model Files Flaresim for Windows files .FSW

XML data files .XML

Table Export Comma separated value files .CSV

Excel files .XLS

Graphics Export JPEG files .JPG

Portable network graphic files .PNG

Windows bitmap files .BMP

Windows meta files .WMF

Enhance windows meta files .EMF

4-16

Interface 4-17

Files can be selected for overwriting by clicking on them.

SaveButtonSaves the file once you have entered the name or selected a file to overwrite. If the file selected already exists you will be asked to confirm that it should be overwritten.

CancelButtonCancels the file save.

New Folder - IconCreates a new sub-folder in the current folder. The folder will be created with the default name “New Folder” and you will then be able to rename as required.

4.6.2 File Open Dialog

The File Open Dialog appears when you select the File - Open menu item or click the Open icon on the tool bar.

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4-18 File Dialogs

The elements of this dialog are essentially the same as the File Save Dialog with the exception that the Save button is replaced by an Open button.

4.6.3 Recent Files Menu

The File Menu displays a list of recently used files which can be used to re-open one of these files directly by selecting it from the menu.

Figure 4-5, File Open Dialog

4-18

Interface 4-19

4.6.4 Update Messages During File Open

When opening a file from earlier versions of Flaresim it is possible that the program will detect parameters that have changed in the current version or detect results that will be changed as a result of changes in the program. When this happens a dialog will be displayed and the user will be asked to acknowledge the information or possibly make a decision between a number of choices.

Further information on these dialogs can usually be found in the help system by pressing F1.

Figure 4-6, Recent Files Menu

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4-20 About View

4.7 About View

The About View is opened using the Help - About menu option.

The purpose of this view is to provide information on the version of the program that may be required when seeking Technical support.

OkButtonCloses the About view.

Figure 4-7, About View

4-20

General Setup 5-1

5-1

Page

5 General Setup

5.1 Case Navigator View . . . . . . . . . . . . . . . . . .3

5.1.1 Command Buttons . . . . . . . . . . . . . . . . . . . . 45.1.2 Tool Bar Buttons . . . . . . . . . . . . . . . . . . . . . 55.1.3 Tree Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5.2 Case Summary View . . . . . . . . . . . . . . . . . .8

5.3 Setup Wizard . . . . . . . . . . . . . . . . . . . . . . .10

5.3.1 Setup Wizard - Common Items . . . . . . . . . 105.3.2 Setup Wizard - Opening View . . . . . . . . . . 125.3.3 Setup Wizard - Fluid Page . . . . . . . . . . . . . 135.3.4 Setup Wizard - Tip Page . . . . . . . . . . . . . . 175.3.5 Setup Wizard - Environment Page . . . . . . 195.3.6 Setup Wizard - Stack Page . . . . . . . . . . . . 215.3.7 Setup Wizard - Receptors Page . . . . . . . . 235.3.8 Setup Wizard - Calculations Page . . . . . . 25

5.4 Preferences. . . . . . . . . . . . . . . . . . . . . . . . .26

5.4.1 Units Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . 275.4.2 Files & Options Tab . . . . . . . . . . . . . . . . . . 305.4.3 Plots Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

5.5 Component Management View . . . . . . . . .40

5-2

5-2

General Setup 5-3

5.1 Case Navigator View

The Case Navigator view, shown in Figure 5-1, provides a summary view of the Flaresim model, showing the objects that have been added to the model and their status. It also provides quick access to any of the object views and enables objects to be added to and deleted from the model.

The Case Navigator view shows the Flaresim model as a tree with the branches showing the different types of object that make up the model.

The Case Navigator is used by clicking a branch of the tree to select it and then clicking one of the command buttons to perform that action on the selected object. For example to open the Pipe Tip in navigator view displayed above, click Pipe Tip then click the View button. A branch can also be double-clicked which will act the same way as the View action.

Figure 5-1, Case Navigator View

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5-4 Case Navigator View

If a branch with sub branches is double-clicked or Viewed it will open a summary view for that object type if it is available. Summary views are available for Environments, Stacks, Tips and Receptor Points.

5.1.1 Command Buttons

The Case Navigator command buttons have the following functions:-

CalculateThis button at the top of the Case Navigator view may be labelled “Click to Calculate”, “Rating Complete” or “Sizing Complete” depending on the current state of the case. It may be clicked at any time to start calculations.

While the case is calculating the surface of the button changes to show a progress bar indicating progress of the calculations. Messages will also be output to the Error/Warnings Log as calculations proceed.

ViewOpens the view for the selected object to allow its data to be viewed or updated.

AddCreates a new object of the selected type and opens its view ready for data input. If an existing object is selected in the tree rather than the parent branch, a new object of the same type is created.

ActivateClears the ignored status for the selected object which restores it to the calculations. Not all objects can be ignored and restored and this button will be greyed out if the action cannot be applied to the selected object.

IgnoreSets the ignored status for the selected object which means that it will not be included in the calculations. Not all objects can be

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General Setup 5-5

ignored and restored and this button will be greyed out if the action cannot be applied to the selected object.

CopyA new object of the same type as the selected object will be created and its contents set to the same values as the selected object. Not all objects can be copied and this button will be greyed out if the action cannot be applied to the selected object.

DeleteDeletes the selected object. No confirmation is required. Not all objects can be deleted and this button will be greyed out if the selected object is a permanent part of the case e.g. the Case Description.

5.1.2 Tool Bar Buttons

The following buttons appear on the Case Navigator tool bar.

This icon opens a drop down menu offering a list of objects that can be added to the case. It is equivalent to selecting the object type branch in the Navigator tree view and clicking the Add button.

This icon saves the case. If the case has an name and has already been saved it will be overwritten. If it is a new case a File - Save As dialog will open. A message indicating success or failure will be written to the File Management Log.

This icon saves the case with a new name. A File - Save As dialog will open to allow the file name to be specified. A message indicating success or failure will be written to the File Management Log.

This icon opens the Report View to allow selection of the print options for the case and to allow printing of the case.

5-5

5-6 Case Navigator View

This icon opens the Print Graphic Report View to allows selection, saving or printing of the graphic reports for the case.

This icon collapses the Case Navigator into a summary view that consists of a vertical tool bar.

Vertical tool bar buttons in the Case Navigator summary are the same as in the standard Case Navigator with the following additions.

This icon expands the Case Navigator to its normal size.

This icon starts the calculations for the case. The colour of the tool bar background is

This icon displays a pop up menu of the objects in the current case. Selecting an object will display its view.

5.1.3 Tree Icons

The icons displayed against each branch and object in the Case Navigator view have the following meanings.

This icon identifies a branch of the model tree that contains a single object that is a permanent part of the model and cannot be added or deleted. Examples of this type of object are the Case Description and Calculation Options object. When a branch of this type is selected the Add, Delete, Copy Activate and Ignore buttons are greyed out since they are not applicable.

This icon identifies branches of the model that contain objects that are not essential to the running of the model. Examples of this type of object are the Receptor Point and Assist Fluid objects.

This icon indicates a branch of the model that contains objects that are essential to the calculation of the model where the required objects are either missing or have

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General Setup 5-7

incomplete data. Examples of this type of object are the Tip and Stack objects.

This icon indicates a branch of the model that contains objects that are essential to the calculation of the model where the required objects are complete and ready for calculation. Examples of this type of object are the Tip and Stack objects.

This icon indicates an object that has been set to an ignored status. Ignored objects are not included in the calculations. Normally where multiple objects may be defined e.g. Tips and Stacks, multiple objects may be ignored as long as there is at least one left active for calculations. The exception is the Environment object where only one can be active; all the others being set to ignored.

This icon indicates an object whose data is incomplete or in error in some way.

This icon indicates an object whose data is complete and ready to calculate.

This icon indicates a branch that has sub-branch objects defined that are not currently displayed. Clicking this icon will expand the tree to show the sub-branch objects.

This icon appears against a branch with displayed sub-branch objects. Clicking it will collapse the branch and hide the sub-branch objects.

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5-8 Case Summary View

5.2 Case Summary View

The Case Summary view (see Figure 5-2) allows the user to enter information to describe the Flaresim model. The Case Summary view is opened by selecting it in the Case Navigator view and clicking the View button or by double clicking on it in the Case Navigator.

Case Data - TitleTextText entered in this field will be printed as the model title on reports.

Case Data - AuthorTextIdentifies the author of this Flaresim file.

Case Data - RevisionTextIdentifies the revision of the Flaresim file.

Figure 5-2, Case Description View

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General Setup 5-9

Case Data - Checked ByTextIdentifies the person responsible for checking the model.

DescriptionTextDescriptive information relevant to the model. For example it is good practice to note sources of environmental data and the contingencies represented by the fluid data.

File Details - Last CalculatedCalculated TextTracks the date and time that the model was last calculated. It is automatically updated each time the model is calculated and cannot be manually updated.

File Details - Last SavedCalculated TextTracks the date that the model was last saved. It is automatically updated each time the model is saved and cannot be manually updated.

File Details - File VersionCalculated TextTracks version of Flaresim that was used when the file was last saved.

File Details - Last Saved AsCalculated TextTracks the name that was used when the file was last saved.

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5-10 Setup Wizard

5.3 Setup Wizard

The Setup Wizard view provides a step by step guide to setting up a basic Flaresim model. It is intended for use by new users to provide the simplest possible interface for defining a new model.

The Setup Wizard provides pages or tabs that allow the user to define in turn the fluid to be flared, details of the flare tip, environment details, details of the flare stack, location of critical receptor points and the calculation options to be used. Each page must be completed before the user can move to the next page. Where possible default data values and options are provided to allow the setup of a new case to be made as simple as possible. When the final page is completed and the Finish button is selected the wizard will automatically create the Flaresim objects required to define the case.

By default, the Setup Wizard will be automatically displayed when starting Flaresim or when creating a new case. If the user does not want to use the Setup Wizard then its view can be simply closed. Experienced users who do not wish to use the Setup Wizard at all can select this option on the Files&Options tab of the Preferences view, see section 5.4.2

5.3.1 Setup Wizard - Common Items

Figure 5-3 below shows the Fluid page of the Setup Wizard and indicates the main areas of the view as follows.

Summary PanelThis provides a summary of the data input provided so far.

Data Entry PanelThis region will change to provide the data entry fields required for the current item.

Help PanelThis region provides additional information about the selected data entry field and will change as different fields are selected. The

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General Setup 5-11

information provided may explain why the data item is required and indicate the range of values allowed as well as typical values.

Command buttonsThese allow the user to move from page to page of the Setup Wizard. The Finish button is only available when all of the required information has been entered

Page TabsThese display the status of each section of the Setup Wizard. The icons used, and have the same meanings as in the Case Navigator view, section 5.1. The Page Tabs also allow the user to move between completed pages of the Setup Wizard.

Figure 5-3, Setup Wizard View

SummaryPanel

Data Entry Panel

Command Buttons

Page Tabs

Help Panel

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5-12 Setup Wizard

5.3.2 Setup Wizard - Opening View

The opening view of the Setup Wizard is shown below.

Unit set to useDrop down listThis field selects the units that will be used by Flaresim.

The drop down list only allows selection from existing unit sets. To create and customise the contents of units sets the File - Preferences menu option can be used, see section 5.4

Figure 5-4, Setup Wizard - Opening View

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General Setup 5-13

5.3.3 Setup Wizard - Fluid Page

The second page of the Setup Wizard is the Fluid page shown below.

Fluid Conditions - TemperatureRange 0 to 1000 KThis field defines the temperature of the fluid going to the flare.

Fluid Conditions - Ref. PressureRange 0.001 to 100 bar aThis field defines the reference pressure at which the temperature of the fluid is specified. Where the operating pressure of the flare differs from the reference pressure, the fluid temperature will be corrected for the change assuming adiabatic conditions. The user can choose not to apply this correction through the Calculation Options view, see chapter 14.

Figure 5-5, Setup Wizard - Fluid Page

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5-14 Setup Wizard

Property CalculationRadio ButtonsThese buttons control how the fluid properties are to be obtained. If the Specified Properties option is selected then the bulk properties of the fluid must be input using the Fluid Properties table as shown in Figure 5-5. Otherwise if the Compositional option is selected the view will change to allow the fluid composition to be specified from which the fluid properties will be calculated.

Fluid Properties - Molecular WeightRange 2 to 1000The molecular weight of the fluid. It is a required entry.

Fluid Properties - LHVRange 0 to 100 MJ/kgThis defines the Lower Heating Value of the fluid, also known as the net heating value. It is a required entry.

Fluid Properties - Cp/CvRange 1 to 5This defines the ratio of the specific heat capacities of the fluid. A default value of 1.2 is provided which may be used where this value is unknown.

Fluid Properties - LELRange 0 to 100%This defines the Lower Explosive Limit of the fluid. A default value of 2% is provided which may be used where this value is unknown. The LEL is only used by the Brzustowski radiation method so the value can safely be left at the default value when other calculation methods are used.

Fluid Properties - SaturationRange 0 to 100%This defines the degree of saturation of the hydrocarbons in the fluid. The default value of 100% assumes that all the fluid is paraffinic hydrocarbon. The saturation is only used by the High Efficiency F Factor method and may safely be left at the default value when other F Factor methods are used.

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General Setup 5-15

Fluid Properties - PcRange 0.001 to 1000 bar aThis defines the critical pressure of the fluid. It is used in the calculation of fluid temperatures and densities. Entry of this value is optional as an internal correlation will be used to estimate the fluids Pc if this value is not provided.

Fluid Properties - TcRange 2 to 1000 KThis defines the critical temperature of the fluid. It is used in the calculation of fluid temperatures and densities. Entry of this value is optional as an internal correlation will be used to estimate the fluids Tc if this value is not provided.

When the Compositional radio button is selected the fluid page is updated to so the Fluid composition table as shown below.

Figure 5-6, Setup Wizard - Fluid Page Compositions

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5-16 Setup Wizard

Composition BasisRadio ButtonsThese buttons select the composition input basis either Mole fraction or Mass fraction

Normalise CompositionButtonClicking this button will normalise the current composition. Unspecified component fractions will be set to 0.0 and the remainder normalised so to give a total fraction of 1.0.

Fluid Composition - FractionRange 0 to 1.0The component composition.

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General Setup 5-17

5.3.4 Setup Wizard - Tip Page

The Tip page of the Setup Wizard is shown below.

Tip TypeRadio ButtonsThis allows selection of the tip type to be used either a Pipe Tip or Sonic tip. If unknown the default Pipe tip will provide the most conservative option.

Tip Sizing - Fluid Mass Flow RateRange 0 to 10000 kg/sDefines the mass flow rate of the fluid to be flared.

Figure 5-7, Setup Wizard - Tip Page

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5-18 Setup Wizard

Tip Sizing - Tip DiameterRange 0.0 to 10 mDefines the diameter of the tip. When the mass flow rate is defined the tip diameter will be automatically updated to show the tip diameter required for the current Mach number. Updating the tip diameter with a specified value will automatically update the Mach number value.

Tip Sizing - Mach NumberRange 0 to 1Defines the tip exit Mach number i.e. the tip exit velocity as a fraction of the sonic velocity. This is defaulted to 0.45 Mach which is a reasonable default for an efficient pipe flare. Updating the Mach number will recalculate the required tip diameter as long as the fluid mass flow rate is known. Alternatively, updating the tip diameter with a specified value will automatically update the Mach number value.

F Factor MethodCheck boxSelects the method that will be used to calculate the fraction of combustion heat that will be radiated from the flame. The F Factor is sometimes known as the emissivity of the flame. The default Generic Pipe method is a conservative general purpose method. The High Efficiency method should only be used for high efficiency tips in good condition burning low molecular weight fluids.

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General Setup 5-19

5.3.5 Setup Wizard - Environment Page

The Environment page which is the fourth page of the Setup Wizard is shown below.

Environment - Wind SpeedRange 0 to 100 m/sThe wind speed to be used for the calculations. A default wind speed of 20 m/s is defined.

Environment - Wind DirectionRange 0 to 360The angle from which the wind is blowing. 0 degrees is North, 90 East, 180 South and 270 West. It is common to do calculations relative to a wind from the North so 0 degrees is the default.

Figure 5-8, Setup Wizard - Environment Page

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5-20 Setup Wizard

Environment - TemperatureRange 10 to 500 KThe environmental temperature. The value is used in surface temperature calculations and gas dispersion calculations.

Environment - HumidityRange 04 to 100%The environmental humidity. The humidity value is used in calculations of the attenuation in radiation due to the atmosphere i.e. the transmissivity calculation. It is only used when the Transmissivity is set to Calculated. The default value of 10% is reasonably conservative.

Environment - Transmissivity SpecRange 0 to 1The value for atmospheric transmissivity to be used if the Transmissivity method is set to User Defined. The default value of 1.0 is conservative and does not allow for any attenuation of radiation when passing through the atmosphere.

Environment - Transmissivity MethodDrop down: UserSpecified / Calculated / CalcNoLimits / WayneThe method to be used for the calculation of the factor for correcting the transmissivity of radiation through the atmosphere. The Default method selects the UserSpecified method which with a specified transmissivity value of 1 is the most conservative. The Calculated and CalcNoLimits methods calculate the transmissivity as a function of the distance travelled by the radiation through the atmosphere and the atmospheric humidity, the difference between them being whether the distance limits applicable to the Hottel derived equation are used (see Methods chapter). The Wayne method calculates transmissivity as a function of both atmospheric temperature and humidity.

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General Setup 5-21

5.3.6 Setup Wizard - Stack Page

The Stack page of the Setup Wizard is shown below

Stack Angle To VerticalCheck boxThis set of check boxes allows rapid selection of some standard angles for the stack which will be updated in the Vertical Angle entry. In general onshore flare stacks are vertical while flare stacks on offshore platforms are often angled at 45 or 60 degrees to Horizontal. If your stack is not a standard angle then select the User check box to input the angle in the table below.

Angle To VerticalRange 0 to 90 degreesThe angle of the stack to the horizontal. Use this field if your stack is not at one of the standard angles.

Figure 5-9, Setup Wizard - Environment Page

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5-22 Setup Wizard

Angle from NorthRange 0 to 360 degreesThe direction in which the stack points. This field is important for non-vertical stacks and should be set with regard to the specified wind direction. It is normal for stacks to be oriented to point into the prevailing wind so if the wind is from the East (90degrees) then it would be normal to set the stack horizontal orientation to 90 degrees as well.

Stack LengthRange 0 to 1000mThe length of the stack. Leaving the value empty will cause the Setup Wizard to create a Sizing case where the stack length will be calculated to meet a defined limiting value for the radiation.

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General Setup 5-23

5.3.7 Setup Wizard - Receptors Page

The Receptors page of the Setup Wizard is shown below

Receptor IDDescriptive NameThe default name provided e.g. RP_1 can be updated with a more descriptive name e.g. Stack Base.

NorthingRange -1000 to 1000mThe location of the receptor point in the Northing direction.

In general the points of maximum radiation are found directly downwind of the stack. So if the wind is from the North you will generally be entering Northing locations with a negative value. For example a Northing value of -10m will be a point 10m down wind.

Figure 5-10, Setup Wizard - Receptors Page

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5-24 Setup Wizard

EastingRange -1000 to 1000mThe location of the receptor point Easting direction.

ElevationRange -500 to 500mThe height of the receptor point. Cases defined through the Setup Wizard define the 0 elevation point as the base of the stack so this is the height of the receptor point above or below the stack base.

Allowable RadiationRange 0 to 31560 W/m2The radiation that is allowed at the receptor point. The table of typical design values shown on this page provides a general guide to the selection of appropriate values.

Add ButtonButtonClicking this button adds a new receptor point to the model.

Delete ButtonButtonClicking this button deletes the current selected receptor point.

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General Setup 5-25

5.3.8 Setup Wizard - Calculations Page

The Calculations page of the Setup Wizard is shown below.

Calculation MethodCheck boxThis allows selection of the calculation method to be used. The default Flaresim API method should generally give a conservative result using industry standard methods. The Mixed method with 25 Flame elements is recommended as a good general alternative.

Figure 5-11, Setup Wizard - Calculations Page

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5-26 Preferences

5.4 Preferences

The File - Preferences menu item provides access to the Preferences View to allow setup of the preferred units, file locations and graphical plot elements.

Read Preference FileButtonReads a preference file. A File Open dialog will be opened to allow the location of the preference file to be specified.

Save Preference FileButtonSaves the current preferences. A File Save dialog will be opened to allow the location of the preferences file to be specified. Preference files are saved as files of type XML.

On startup, Flaresim first searches for a file called Preferences.xml in the folder User Documents\Softbits\Flaresim X.Y where X.Y is

Figure 5-12, Units Tab

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General Setup 5-27

the version number. If not found the default Preferences.xml file is read from the SharedProgramData folder.

The SharedProgramData folder referred to above is typically the folder C:\Documents and Settings\All User\Application Data\ Softbits\Flaresim X.Y on a Windows XP system or the folder C:\ProgramData\Softbits\Flaresim X.Y on a Vista or Windows 7 system.

5.4.1 Units Tab

The Units tab of the Preferences view (see Figure 5-12) is used to define the units of measure used to display and interpret values on the data entry views.

Flaresim uses the concept of a Unit Set which defines all of the units to be used for a single case. Two Unit Sets, the Default SI and Default Field sets are provided as basic sets that cannot be changed. A third European unit set is provided which can be modified. New Unit Sets can be created by copying an existing Unit Set and then customising it.

A default range of units is provided for each type of unit used by Flaresim. The Units tab also allows new units to be defined by defining their name and conversion to the internal unit used by Flaresim.

Unit Sets - ListList boxShows the Unit Sets that have already been defined in the Preferences file. A Unit Set may be activated by selecting it in this list. On activation all open data views are immediately updated to display values in the new units.

Unit Sets - Rename Unit SetText entryAllows the name of a user defined Unit Set to be updated. The names of the default Unit Sets cannot be changed.

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5-28 Preferences

Unit Sets - Copy Unit SetButtonCopies the selected Unit Set to create a new one. The new Unit set will be given a default name that can then be updated to describe it.

Unit Sets - Delete Unit SetButtonDeletes the selected Unit Set. The default internal Unit Sets cannot be deleted and this button will be inactive when these are selected.

Unit Select - TableTableShows a list of the unit types used in Flaresim with the current unit defined for the selected Unit Set and the current format specifier. To update the unit or format used for a particular unit type e.g. Temperature, move to the appropriate row and then select the required unit in the Selected Unit column and update the format specifier in the Format column.

Unit Select Table - Selected Unit ColumnDrop down ListAllows selection of the unit to be used for the currently selected unit type. As the selection is changed the conversion factors for the unit are displayed in the Unit Definition fields at the bottom of the view.

Unit Select Table - FormatFormat specifierAllows the output format of the selected unit type to be specified. Format specifiers should be of the form:-###0.000where the # symbol denotes the space allowed for leading digits and the 0.000 section denotes the number of decimal places that will be used for output.

Unit Select - AddButtonAllows new units to be defined for a particular unit type. Clicking the button displays a pop up window to allow the new unit name to be defined as shown below.

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General Setup 5-29

Clicking the OK button on this window activates the Unit Definition fields and the Accept button.

Unit Select - DeleteButtonAllows units to be deleted. Clicking the button will delete the currently selected unit. A confirmation dialog will be displayed to confirm the action. Only user added units can be deleted and the button will be greyed out if the selected unit is not a user added unit.

Unit Select - AcceptButtonAccepts the updated unit information.

Unit Definition - MultiplierNumeric entryDefines the multiplication constant required to convert the new unit to the internal default unit which is displayed.

Unit Definition - OffsetNumeric entryDefines the offset to be added to convert the new unit to the internal default unit which is displayed. Note the offset is added after multiplication.

Figure 5-13, New Unit Name Window

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5-30 Preferences

5.4.2 Files & Options Tab

The Files&Options tab of the Preferences view allows the location of the units and components files to be specified along with other options.

Default Files - UnitsFile name entryDefines the name of the unit conversion factors file, normally Units.xml. If no folder path is specified Flaresim will expect to find this in the SharedProgramData folder. The Browse button allows the file to be located using a standard File Dialog.

Default Files - Component LibraryFile name entryDefines the name of the component library file, normally Librarycomponents.xml. If no folder path is specified Flaresim will expect to find this in the SharedProgramData folder. The Browse button allows the file to be located using a standard File Dialog.

Figure 5-14, Files Tab

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General Setup 5-31

This allows the user to create dedicated component files to be created and used for specialised applications.

Default Files - Report Layout FileFile name entryDefines the name of the style sheet file (XSL file) that will be used to layout printed reports. By default this will be Flaresim.xsl. If no folder path is specified Flaresim will expect to find this in the SharedProgramData folder. Clients are able to create customised report style sheets using standard XSL language to change the layout of Flaresim reports.

Default Files - Graphic Report LayoutFile name entryDefines the name of the graphic report layout file to be used by default. Standard graphic report layout files have a .lay extension and are defined for A4 and US Letter paper sizes and for systems with one or more stacks and one or more tips. If no folder path is specified Flaresim will expect to find the file in the SharedProgramData folder.

The default layout file selected here can be reset for individual receptor grids or dispersion objects on the Graphic Report tab of the relevant view.

The contents of the .lay files describe the location and formatting of isopleth charts and accompanying data items and descriptive text using XML syntax. The XML elements recognised in these files are described in Appendix A of this manual.

Default Files - Wizard Help FileFile name entryDefines the name of the file containing the help information displayed on the Setup Wizard. By default this file is called WizardHelp.xml. Flaresim will expect to find this file in the SharedProgramData folder.

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5-32 Preferences

Default Files - Error Log FileFile name entryDefines the name of the file which will be used to record any errors generated as you run Flaresim. By default the file will be saved in the SharedProgramData folder. Error messages will only be recorded if the Use Error Log option is selected.

Option Settings - Use Setup WizardCheck boxWhen selected, Flaresim will display the Setup Wizard whenever Flaresim is opened without specifying a file to load or when a new Flaresim case is created. The Setup Wizard provides a step by step guide to creating a basic Flaresim model. Use of the Setup Wizard is described in section 5.3.

Option Settings - Use Specified FormatsCheck boxWhen selected, Flaresim will use the defined Format values for each unit when displaying values in the Input Tables on the various views. Otherwise values will be displayed to 3 significant figures.

Option Settings - Log Errors to FileCheck boxWhen selected, Flaresim will record all the exception errors displayed to the log file defined in the Files section.

Option Settings - Maximise ViewCheck boxWhen selected, Flaresim will display all newly opened or created cases in a maximise Case View, overlaying the previously visible view.

5.4.3 Plots Tab

The Plots tab of the Preferences view is used to customise the appearance of the isopleth plots in the Receptor Grid view and the plots in the Graphical Reports.

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General Setup 5-33

Plot TypeDrop Down List: Radiation Isopleth / Noise Isopleth / Temperature Isopleth / Concentration Isopleth / Dispersion Plot / Wind Rose PlotThis drop down list selects the type of plot that the customisation options displayed will be applied to.

The customisation options are viewed and updated through three sub tabs, for Plot Details, Contour Details and Text Details.

On the Plot Details tab, see Figure 5-15, it is possible to set the following options.

Plot Options - Display GridCheck boxWhen selected plots will show a background grid.

Plot Options - Display FlameCheck boxWhen selected isopleth plots will show a line representing the shape of the flames from any active flare tips.

Figure 5-15, Plots Tab

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5-34 Preferences

Plot Options - Display StackCheck boxWhen selected isopleth plots will show lines representing the size and orientation of active flare stacks.

Plot Options - Display TipCheck boxWhen selected isopleth plots will show lines representing the size and orientation of active flare tips.

Plot Options - Display ShieldCheck boxWhen selected isopleth plots will show lines representing the intersection of active shield sections with the plane of the isopleth.

Note that it is the intersection that is displayed not the projection of the shield on the isopleth. If plan view isopleth is at ground level i.e. 0m then the shields will require at least one point with an elevation dimension < 0m in order to intersect with the isopleth plane.

Plot Parameter - Number of linesInteger value 1 to 9This value determines the number of grid lines that will be displayed for each axis of the isopleth plots.

Plot Parameter - Flame ThicknessInteger value 1 to 50This values defines the width in pixels of the line that will be drawn to represent the flame shape.

Plot Parameter - Stack ThicknessInteger value 1 to 50This values defines the width in pixels of the line that will be drawn to represent each active stack on the isopleth plots.

Plot Parameter - Tip ThicknessInteger value 1 to 50This values defines the width in pixels of the line that will be drawn to represent the each active tip on the isopleth plots.

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General Setup 5-35

Plot Parameter - Shield ThicknessInteger value 1 to 50This values defines the width in pixels of the line that will be drawn to represent the shield sections on the isopleth plots.

Plot Colour - Grid ColourColour DialogThis shows the colour that will be used for the background of the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

Colours are selected in the dialog by clicking on the colour required and then clicking the Ok button. To close the dialog without changing the colour click the Cancel button.

Plot Options - Flame ColourColour DialogThis shows the colour that will be used to draw the line representing the flame shape on the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

Plot Options - Stack ColourColour DialogThis shows the colour that will be used to draw the line representing the flare stacks on the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

Figure 5-16, Colour Dialog

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5-36 Preferences

Plot Options - Tip ColourColour DialogThis shows the colour that will be used to draw the line representing the flame shape on the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

Plot Options - ColourColour DialogThis shows the colour that will be used to draw the line representing the shield sections on the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

On the Contour Details tab, see Figure 5-17, it is possible to select the following options for the 10 contour lines that are available for each type of plot.

Contour Details - ValueData InputThis column defines the value for the selected isopleth contour in the units defined at the head of the column.

Figure 5-17, Contour Details

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General Setup 5-37

Contour Details - DisplayCheck boxThis column specifies whether the selected isopleth contour will be displayed. Set the check box to display the contour, clear it to hide the contour. Contours

Contour Details - ColourColour DialogThis column defines the colour to be used for the selected isopleth contour. Double click the sample panel to open the Flaresim colour dialog to change the colour.

Contour Details - WidthData InputThis column defines the line width used to draw the selected isopleth contour.

Contour Details - ValueDrop Down List: Solid / Dash / Dot / DashDot / DashDotDotThis column selects the line style used to draw the selected isopleth contour.

The Text Details tab, see Figure 5-18, allows the following settings to be defined.

5-37

5-38 Preferences

Text Options - Select Text ItemSelect RowThe rows of this table describe the different text elements that can appear on an isopleth plot. The display properties of each different text element can be set by selecting the row and then using the fields below to modify the properties.

Not all of the defined properties may be supported for all of the text elements. Where a property cannot be set it will be grayed out while that text element is selected.

Text Options - Display ItemCheck boxThis controls whether the selected text element will be displayed. Set the check box to display the item, clear it to hide it.

Text Options - SampleFont DialogThe Sample column displays a sample of the font style that is currently defined for the selected text item. Double clicking the sample text opens a standard windows font dialog to allow the family, size and style of the font to be set for the selected text item.

Figure 5-18, Isopleth Text Details

5-38

General Setup 5-39

Text Options - SpacingInteger value 1 to 20This determines the spacing between the selected text element and the item it describes e.g the spacing between the X-Axis of the isopleth plot and the X-Axis of the graph. The value is expressed as a percentage of the dimensions of the isopleth plot.

Figure 5-19, Font Dialog

5-39

5-40 Component Management View

5.5 Component Management View

The Component Management view (see Figure 5-20) is used to maintain and update the library of component data that may be used to allow fluid properties to be calculated from their component composition. The Component Management view is opened by selecting it in the Case Navigator view and clicking the View button.

The list of components defined for the model is shown in the Available Components list. Selecting a component in this list will display its properties in the three tabbed pages at the bottom of the view. If the component selected is a user added component the Remove Selected Component and Edit Selected component command buttons will be activated.

Figure 5-20, Component Management View

5-40

General Setup 5-41

New components can be added to the component library by clicking the Add New Component button. This displays a pop-up window (see Figure 5-21) to allow the entry of the new component’s name. When this has been entered click the OK button and the component will be added to the list in the Component Manager view. and its properties will be displayed ready for entry.

Data for a new component or existing data for a user added component is updated through the three tabbed views, Properties, Structure and Enthalpy coefficients as described below. While data is being updated an “Edit Component” information panel will be displayed below the command buttons.

The options on the Properties tab are shown in Figure 5-20 above.

Mole WeightRange: 2 to 1000 The molecular weight of the component.

LHVRange: 0 to 200MJ/kgThe net, or lower heating value of the component. It is a common error in the design of flare systems to use the gross heating value.

For most hydrocarbon components this value will be of the order of 46 MJ/kg

Cp / CvRange: 1.01 to 5.0The ratio of the specific heat capacities of the component. If the value is unknown we would recommend using a value of 1.2.

Figure 5-21, Component Name Popup

5-41


SaturationRange: 0 to 100%The percentage saturation of the component.

LELRange: 0.0 to 100.0%The lower flammability limit of the component as a volume percentage.

Critical TemperatureRange: 10 to 10,000 KThe critical temperature of the component.

Critical PressureRange: 0.01 to 1,000 baraThe critical pressure of the component.

On the Structure tab of the component data entry view the number of atoms of each listed atom in the component should be entered, an example for Methane is shown below.

This number is used in the calculation of combustion products. The list of atoms cannot be updated. If other atoms are needed they must be defined in the LibraryComponents.xml file along with details of their combustion products.

The final tab of the Component data entry is the enthalpy coefficients tab as shown below.

Figure 5-22, Component Structure Input

5-42

General Setup 5-43

Flaresim calculates the enthalpy of fluids and combustion gases by summing the contributions made by each component. The individual component enthalpy contributions are calculated using the following polynomial equation.

whereE is the enthalpy in J/kg T is the temperature in KA, B, C, D, E, F are constants

The data entry table for the enthalpy coefficients allows the enthalpy unit for each constant to be selected but the values entered will always be based on a temperature in K.

Once the component property data has been defined click the Accept Edit button to complete definition of the new component. If for any reason you wish to abandon creation of a new component at the property data entry stage then click the Cancel Edit button.

Components that have been added by the user may be updated by selecting it in the list and clicking the Edit Component Data button. This option is not available for components from the Flaresim database.

To remove a component from the library, select it in the list and click the Remove Selected Component button.

Figure 5-23, Enthalpy Coefficients Data Entry

E A B T⋅ C T2⋅ D T

3⋅ E T4⋅ F T

5⋅+ + + + +=

5-43


5-44

Fluids 6-1

6-1

Page

6 Fluids

6.1 Fluid View . . . . . . . . . . . . . . . . . . . . . . . . . . .4

6.1.1 Common Fields . . . . . . . . . . . . . . . . . . . . . . 46.1.2 Properties Tab . . . . . . . . . . . . . . . . . . . . . . . 46.1.3 Composition Tab . . . . . . . . . . . . . . . . . . . . . 76.1.4 Combustion Results Tab . . . . . . . . . . . . . . . 8

6.2 Assist Fluid View . . . . . . . . . . . . . . . . . . . . 11

6-2

6-2

Fluids 6-3

The Fluid object defines the properties of the fluids to be flared through a flare tip. The fluid properties may either be entered directly or calculated from a defined composition. A single set of fluid properties can be assigned to one or more flare tips.

Fluid objects may be created using the Fluid option from the Add drop down menu or by selecting the Fluid branch in the Case Navigator view and clicking the Add button.

An existing Fluid object may be viewed by double clicking it in the Case Navigator view or by selecting it in the Case Navigator view and clicking the View button.

Fluid objects will be included in the calculations when they are assigned to a flare tip through the Tip view. A Fluid may be assigned to more than one flare tip. Unassigned fluids take no part in the calculations.

A Fluid object can be deleted either by clicking the Delete button on its view or by selecting it in the Case Navigator view and clicking the Delete button on this view.

The Assist Fluid object both identifies the additional fluids that may be fed to a flare tip to improve combustion and also defines the information needed to calculate the flow of the assist fluid required. Like Fluid objects, Assist Fluids are included in the calculations only when assigned to a flare tip.

Assist Fluid objects may be created using the Assist Fluid menu option from the Add drop down menu or by selecting the Assist Fluid branch in the Case Navigator view and clicking the Add button.

An existing Assist Fluid object may be viewed by double clicking it in the Case Navigator view or by selecting it in the Case Navigator view and clicking the View button. Assist Fluid objects may be deleted either through the Case Navigator view or by using the Delete button on the Assist Fluid view.

6-3

6-4 Fluid View

6.1 Fluid View

The following figure shows the Fluid view for entering and updating fluid data.

6.1.1 Common Fields

NameTextEnter text to identify this Fluid object.

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this fluid object is complete and ready for calculation.

6.1.2 Properties Tab

The Properties tab of the Fluid view, see Figure 6-1, has the following data entry fields. Note that all of these fields except the

Figure 6-1, Fluid View

6-4

Fluids 6-5

temperature and reference pressure will be calculated from the fluid composition if this is entered.

Conditions - TemperatureRange: 10 to 1000KThe temperature of the fluid at the tip exit. Note that this is the temperature of the fluid at the defined reference pressure.

If either a Steam or Air assisted flare tip is being used this temperature is the fluid temperature before mixing with the steam or air flow.

Conditions - Ref. PressureRange: 100 to 2000000 PaThe reference pressure at which the fluid temperature is defined.

The fluid temperature will be corrected from this pressure to other pressures assuming adiabatic compression/expansion if the adiabatic temperature correction calculation option is set.

Properties - Mole WeightRange: 2 to 1000The molecular weight of the fluid being flared.

Properties - Mass Energy or LHVRange: 0 to 200MJ/kgThe net or lower heating value of the fluid. It is a common error in the design of flare systems to use the gross heating value of the fluid. We are interested in the net heat released by the flame.

For most hydrocarbon fluids without inerts this value will be of the order of 46 MJ/kg.

Properties - Cp / CvRange: 1.0 to 5.0This field defines the ratio of the specific heat capacities of the fluid. It is only required and used when the fluid is a vapour.

If the value is unknown we would recommend using a value of 1.2.

6-5

6-6 Fluid View

Properties - LELRange: 0.0 to 100.0%The lower flammability limit of the fluid as a volume percentage.

This property is used by the Brzustowski method for calculation of flame shape. It is not used by any of the other methods, in which case any value may be entered.

Properties - SaturationRange: 0 to 100%The percentage of saturated hydrocarbon molecules in the fluid on a mole basis. This is used by the Flaresim method for estimation of the fraction of heat radiated by a flame (emissivity). It is not used by any of the other methods in which case any value may be entered.

For inert or non-hydrocarbon fluids and components assume 100% saturation since this leads to combustion with a flame of lower luminosity.

Critical Properties - Critical TemperatureRange: 10 to 1000KThe critical temperature of the fluid. It is used in the calculation of the compressibility factor which in turn is used in the calculation of the fluid density. If a value is not supplied, the fluid’s critical temperature will be estimated using an internal correlation based on mole weight.

Critical Properties - Critical PressureRange: 0.01 to 1000 baraThe critical pressure of the fluid. It is used in the calculation of the compressibility factor which in turn is used in the calculation of the fluid density. If a value is not supplied, the fluid’s critical pressure will be estimated using an internal correlation based on mole weight.

6-6

Fluids 6-7

6.1.3 Composition Tab

Table - Component NameSelected componentsShows the list of components selected for use in the model.

Components are added to the list by clicking the Add Component button to open the Component List view; see Figure 6-3. Highlight one or more components in the list that you wish to add and click the OK button. The required components will be added to the component list and the Component List view will close.

Components are removed from the list by clicking the Remove Component button to open the Component List view; see Figure 6-3. Then select one or more components that you wish to remove and click the OK button. The selected components will be removed from the current component list and the Component List view will close.

Figure 6-2, Composition Tab

6-7

6-8 Fluid View

Table - Composition ValuesRange: 0 to 1.0Specifies the fraction of each component in fluid on either a mole or a mass basis as determined by the radio button selection to the right of the table.

Composition BasisRadio Button: Mass/MoleThis radio button selects the basis for the composition data. Note that changing it does not convert any existing component fraction data to the new basis.

As component fractions are updated, the running total of the fractions is updated. A composition can be completed by clicking either the Normalise button to set remaining fractions to 0.0 and normalise current totals to add to 1.0 or by clicking the Calculate Last Fraction button to set a single unspecified component fraction to the value required to make the overall fraction equal to 1.0.

6.1.4 Combustion Results Tab

The following figure shows the Combustion Results tab. This view displays the combustion results calculated for the fluid.

Figure 6-3, Component List view

6-8

Fluids 6-9

These results are calculated directly from the specified composition when this is available. When the composition has not been specified, a composition is calculated for the Fluid using the defined mole weight as the basis. Essentially the composition is assumed by selecting the two straight chain hydrocarbon components, C1 through C10 from the data base that have mole weights immediately lower than and higher than the specified mole weight. The proportion of these two components is then calculated to provide the same mole weight.

Fluid Ideal Enthalpies - At Fluid TempCalculated Result, J/kgThe ideal enthalpy of the fluid at the specified temperature.

Fluid Ideal Enthalpies - At 25CCalculated Result, J/kgThe ideal enthalpy of the fluid at 25C.

Flue Gas Results - Flue Gas FlowCalculated result, mole/moleThe flow of flue gas generated by complete combustion of 1 mole of the fluid with the stoichiometric quantity of oxygen.

Figure 6-4, Fluid View, Combustion Results

6-9

6-10 Fluid View

Flue Gas Results - O2 RequiredCalculated result, mole/moleThe stoichiometric quantity of oxygen required for combustion of 1 mole of the fluid.

Stoichiometric Flue Gas CompositionCalculated result, mole fractionThe composition of the flue gas resulting from stoichiometric combustion of the fluid.

6-10

Fluids 6-11

6.2 Assist Fluid View

The following figure shows the Assist Fluid view for entering and updating assist fluid data.

NameTextEnter a name to identify this assist fluid.

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this Assist Fluid object is complete and ready for calculation.

TypeDrop down list: Air / Steam/WaterSelects the type of assist fluid to be used. Steam/Water indicates that Steam will be used with vapour flares and Water with liquid flares.

Flow CalculationsDrop down list: User / SmokelessIf this is set to User then a specific flow rate for the Assist Fluid will need to be specified when the Assist Fluid is assigned to a Tip. If set to Smokeless then the flow rate of the Assist Fluid will be calculated according to the following settings as shown in Figure 6-6.

Figure 6-5, Assist Fluid View

6-11

6-12 Assist Fluid View

Smokeless MethodDrop down list: Flaresim/API/UserRatioSelects the method to be used by Flaresim to calculate the flow of assist fluid required for smokeless operation. The Flaresim method is a propriatory correlation supplied by National Air Oil. The API method is the method described in API RP521. The UserRatio allows the user to specify the flow ratio of assist fluid required for smokeless operation.

The validity of these options varies with the type of assist fluid selected.

Air The allowed methods are Flaresim and UserRatio. If the API method is selected an error message will displayed when the model is calculated.

Steam/Water Any of the allowed methods may be used.

Smokeless Flow RatioRange: 0.001 to 10.0 but see descriptionSpecifies the ratio of the mass flow of the assist fluid to the mass flow of the fluid being flared. This field is displayed when the UserRatio smokeless method is selected.

When Air is the assist fluid, high ratios of 5.0 or more may be used. When Steam/Water is the assist fluid the mass ratio should not

Figure 6-6, Assist Fluid View for Smokeless Operation

6-12

Fluids 6-13

exceed 0.5 since this would lead to flame instability and a potential flameout.

Apply Correction to Fraction Heat RadiatedCheck boxIf selected, Flaresim will calculate a correction to the flame length resulting from the assist fluid.

Apply Correction to Flame LengthCheck boxIf selected, Flaresim will calculate a correction to the flame length resulting from the assist fluid.

6-13

6-14 Assist Fluid View

6-14

Environment 7-1

7-1

Page

7 Environment

7.1 Environment View . . . . . . . . . . . . . . . . . . . .4

7.1.1 Common Fields . . . . . . . . . . . . . . . . . . . . . . 47.1.2 Overall Tab . . . . . . . . . . . . . . . . . . . . . . . . . . 57.1.3 Wind Rose Tab . . . . . . . . . . . . . . . . . . . . . . 107.1.4 Dispersion Data Tab. . . . . . . . . . . . . . . . . . 13

7.2 Environment Summary View. . . . . . . . . . .15

7-2

7-2

Environment 7-3

The Environment object allows the definition of the data needed to model flares in different environmental conditions. The data allows characterisation of different geographical locations ranging from desert conditions to Arctic conditions or characterisation of different weather conditions at a single location.

An individual Flaresim run is always carried out for a single set of environmental data. A Flaresim model file can contain multiple Environment objects to allow rapid recalculation of the model with a different set of environmental data.

Environment objects may be created using the Environment option in the Add Item drop down menu or by selecting the Environment branch in the Case Navigator and clicking the Add button.

An existing Environment object may be viewed by selecting it in the View drop down menu option, by double clicking it in the Case Navigator or by selecting it in the Case Navigator and clicking the View button.

The Environment object to be used for calculations is set by selecting it in the Case Navigator and clicking the Activate button. Since only one set of environmental data can be active at a time, all other Environment objects will be set to Ignored. An Environment object can also be Ignored by selecting the check box on its view. One Environment object must be active and complete to allow calculations to proceed.

An Environment object can be deleted either by clicking the Delete button on its view or by selecting it in the Case Navigator and clicking the Delete button on this view.

A summary view showing the main details of all of the Environment objects in a case can be displayed by double-clicking the Environment branch header in the Case Navigator or by selecting the Environment branch and clicking the View button.

7-3

7-4 Environment View

7.1 Environment View

The figure below shows the Environment view for defining and updating environmental data.

7.1.1 Common Fields

NameTextA descriptive name to identify this Environment object. The name supplied will be processed to remove illegal characters.

IgnoredCheck boxClear to select this Environment object for calculations or set it to ignore this Environment object. Only one Environment can be active

Figure 7-1, Environment view

7-4

Environment 7-5

for calculations so activating an Environment object by clearing the ignored check box will automatically set all the other Environments in the model to ignored.

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this Environment object is complete and ready for calculation.

7.1.2 Overall Tab

The data items in the Overall tab of the Environment view are shown in Figure 7-1 above.

Wind - SpeedRange: 0 to 100 m/sA constant wind speed is assumed.

In theory the windspeed varies with elevation. This variation is ignored in the calculation of the flame profile since it is not generally included in published flame shape calculation methods. The variation in wind speed with elevation is included in gas dispersion calculations - see Dispersion Data tab.

The following table gives standard wind speed conversions. Note the Beaufort scale wind speed cannot be entered directly since there is no continuous or linear conversion to other windspeed measurements.

knots mph ft/s m/sBeaufort

Scale

0 0.0 0.0 0.0 0

2 2.3 3.3 1.0 1

4 4.6 6.6 2.0 2

8 9.2 13.5 4.1 3

7-5


Wind - DirectionRange: 0 to 360 from NorthThe direction from which the wind blows. Generally the worst or most prevalent wind direction can be determined by examination of the wind rose for the site in question.

Atmosphere - TemperatureRange: 10 to 500KThe ambient temperature of the atmosphere is used in the calculation of the equilibrium surface temperatures of metallic surfaces exposed to the flare’s thermal radiation. It is also used in gas dispersion calculations.

Atmosphere - HumidityRange: 4 to 100%The relative humidity defines the water content of the atmosphere in terms of the partial pressure of water vapour in the air relative to the vapour pressure of water at the same temperature. Standard charts are available relating the wet and dry bulb temperature measurements to the relative humidity, an example of which can be found in “The Chemical Engineers Handbook”. The humidity value is used in calculation of Transmissivity as described below.

Atmosphere - PressureRange: 0.01 to 10.0 bar aThe atmospheric pressure is used to calculate the exit density of the flared gas and hence its exit velocity.

12 13.8 20.3 6.2 4

18 20.7 30.5 9.3 5

24 27.6 40.7 12.4 6

28 32.2 47.2 14.4 7

34 39.1 57.4 17.5 8

40 46.0 67.6 20.6 9

knots mph ft/s m/sBeaufort

Scale

°

7-6

Environment 7-7

Background - Solar RadiationRange: 0 to 100,000 W/m2

The incident solar radiation for the site. Typical values for different geographical locations are given in the following table.

Background - NoiseRange: 0 to 150 dBThe background noise is used as a reference noise level to which the noise from the flare system is added.

The following table gives typical noise levels for everyday situations.

LocationSolar Radiation

(W/m2)

North Sea 475-630

Middle East 945-1050

UK Land 630-800

Intensity (dB) Situation

0 Threshold of hearing

10 Virtual silence

20 Quiet room

30 Watch ticking at 1m

40 Quiet street

50 Quiet conversation

60 Quiet motor at 1m

70 Loud conversation

80 Door slamming

90 Busy typing room

100 Near loud motor horn

7-7


Include Solar RadiationCheck boxSelect this check box to include solar radiation in the calculation of radiation received at a point.

The decision on whether to include solar radiation when designing flare systems is one for the user. Including it leads to more conservative designs and its impact can be significant if the flare system design is controlled by low total radiation limits at longer distances from the flare. Some consider it more realistic to exclude solar radiation in calculations.

Include Background NoiseCheck boxSelect this check box to include background noise in the calculation of total noise received at a point.

Transmissivity - MethodOptions: User/Calculated/CalcNoLimits/WayneThe value for the atmospheric transmissivity may be either specified by the user or calculated. The calculation method used is described in section 14.1.5 and estimates transmissivity as a function of the relative humidity at the site and the distance of the receptor from the flame. The correlation is strictly valid for distances between 30-164 m (100-500 ft) and for relative humidities greater than 10%. Outside of these ranges the correlation may still give acceptable results.

If User is selected the value for the atmospheric transmissivity must be entered.

If Calculated is selected the value for the relative humidity at the site must be entered. The transmissivity will be calculated, enforcing the distance limits of the correlation i.e. distances less than 30m will be

110 Pneumatic drill

120 Near aeroplane engine

130 Threshold of pain

Intensity (dB) Situation

7-8

Environment 7-9

set to 30m (100ft) and distances greater than 164m (500 ft) set to 164m. The minimum and maximum values of transmissivity used during the calculations will be displayed.

If CalcNoLimits is selected the value for the relative humidity at the site must be entered. The calculation will be done without enforcing the distance limits of the correlation. The mi nu mum and maximum values of transmissivity used during the calculations will be displayed after calculations are complete.

If Wayne is selected the transmissivity is calculated using a method that includes the effect of both relative humidity and ambient temperature - see section 14.

Note a single value of calculated transmissivity cannot be displayed since in a typical Flaresim run multiple distances between individual flame elements and multiple receptor points will be considered. Tracking of each transmissivity value used would be of limited use so the compromise is to show the minimum and maximum value calculated.

Calculated atmospheric transmissivities should not be selected if you are modelling hydrogen or hydrogen sulphide flares which burn with little or no luminous radiation.

Transmissivity - ValueRange: 0 to 1.0Atmospheric transmissivity defines the degree of attenuation of the thermal radiation due to atmospheric conditions. It is expressed as the fraction of the radiation which is received at the receptor point. It must be specified if the Transmissivity Method is set to User.

A value of 1.0 should normally be taken unless exceptional circumstances are deemed applicable. A specified value of 1.0 for the transmissivity will mean no attenuation of radiation in the atmosphere and lead to a more conservative design.

7-9


Transmissivity - Min ValueCalculated ResultThe minimum value of transmissivity calculated when the Transmissivity Method is not set to User.

Transmissivity - Max ValueCalculated ResultThe maximum value of transmissivity calculated when the Transmissivity method is not set to User.

7.1.3 Wind Rose Tab

The Wind Rose tab of the environment view allows a range of wind speeds from different directions to be modelled and the results plotted on a single graph for a each receptor point.

There are two methods of setting up the matrix of wind speeds against direction, either for all directions at a range of wind speeds or for a specific wind speed for each direction. It is also possible to enable sizing calculations based on the Wind Rose data to calculate the sizing for each defined wind speed and direction to find the worst case.

No wind rose calculationsRadio buttonSelecting this button disables wind rose calculations.

Run calculations on all wind directions for specified speedsRadio buttonSelecting this option activates Wind Rose calculations for all wind directions for the specified range of wind speeds. The view will change to display a table to enter the wind speeds to be used as shown below.

7-10

Environment 7-11

When this option is selected, multiple lines, one for each wind speed will appear on the Wind Rose plots for each Receptor point.

Wind Speed TableRange 0 to 100 m/sDefine the wind speeds for which wind rose calculations are required. At least one value must be defined.

Run each wind direction with a specific speedRadio buttonWhen this option is selected Wind Rose calculations will be activated for a specific wind speed for each wind direction. The view will change to allow the matrix of wind speeds to be defined as shown below.

When this option is selected, a single line will appear on the Wind Rose plots for each Receptor point.

Figure 7-2, Wind Rose Tab, Range of speeds for all directions

7-11


Wind Speed TableRange 0 to 100 m/sDefine the wind speed for each wind rose direction. A value must be defined for each direction to complete the data input.

Use wind rose data for stack sizingCheck boxThis option is available when wind rose calculations are enabled. Selecting this option will use the selected wind rose data and method during sizing calculations. Instead of the stack being sized solely to meet the wind speed and direction defined on the Overall tab of the Environment view, multiple sizing calculations will be done for each of the wind rose data points defined. The wind direction and speed used for the final sizing can be viewed on the Sizing tab of the Calculation Options view.

Note this option will slow the calculations significantly.

Figure 7-3, Wind Rose Tab, Specified speed for each direction

7-12

Environment 7-13

7.1.4 Dispersion Data Tab

The entries on the Dispersion Data tab are shown below.

Dispersion Data - Atm. Stability ClassDrop down List: PasquillA through PasquillFThis defines the atmospheric stability class to be used to characterise the atmospheric turbulence for both gaussian and jet dispersion calculations.

Flaresim uses the widely used Pasquill stability class designation from A to F where A is the most turbulent or most unstable atmosphere and F the least turbulent or most stable.

Figure 7-4, Dispersion Data Tab

7-13


Dispersion Data - Terrain ClassDrop down List: Rural / UrbanThis parameter characterises the terrain roughness to be used in the gaussian dispersion calculations.

Dispersion Data - Surface RoughnessRange 0.0001 to 0.3 m/sThis defines the surface roughness used in jet dispersion calculations.

Dispersion Data - Wind Reference HeightRange 0.1 to 200 mThe reference height at which the wind speed is specified. This will be used together with the atmosphere and terrain characterisation information to calculate the wind speed at the stack height in dispersion calculations. At present this correction is not used in the flame shape calculations.

7-14

Environment 7-15

7.2 Environment Summary View

The Environment Summary view is shown below. It may be opened by selecting Environment collection branch in the Case Navigator and clicking the View button or by double-clicking the Environment collection branch.

The view provides a summary of the basic information for all the Environment Objects in the case and can be used to update input data items as well as review results.

Export TableButtonClicking this button opens a File Save dialog to allow the Environments summary table to be saved as a comma separated value (CSV) file, an Excel format file (XLS) or tab separated text file(TXT).

Figure 7-5, Environment Summary View

7-15

7-16 Environment Summary View

7-16

Stacks 8-1

8-1

Page

8 Stacks

8.1 Stack View. . . . . . . . . . . . . . . . . . . . . . . . . . .4

8.2 Stack Summary View . . . . . . . . . . . . . . . . . .8

8-2

8-2

Stacks 8-3

The Stack object allows definition of data to describe each flare Stack. A flare Stack or boom acts as the support for one or more flare tips and its length and orientation is a critical part of the design of a safe flare system. Flaresim offers a sizing calculation option where the length of a single flare stack can be calculated to meet a defined thermal radiation limit at a point in the site.

A Flaresim model may contain multiple Stack objects allowing the modelling of sites containing multiple flares.

Stack objects may be created selecting the Stack menu option in the Add Items drop down menu or by selecting the Stack branch in the Case Navigator and clicking the Add button.

An existing Stack object may be viewed by selecting it in the View drop down menu option; by double clicking it in the Case Navigator or by selecting it in the Case Navigator and clicking the View button.

All defined Stack objects will be included in the calculations unless they have been set to Ignored. A Stack may be set to ignored by selecting it in the Case Navigator and clicking the Ignore button. An Ignored Stack object can be restored to the calculations by selecting it in the Case Navigator and clicking the Activate button. Alternatively a Stack object can be ignored and restored by setting or clearing the Ignored check box on its view. Ignoring a stack will exclude all the tips located on it from Flaresim’s calculations.

A Stack object can be deleted either by clicking the Delete button on its view or by selecting it in the Case Navigator and clicking the Case Navigator Delete button.

A Stack Summary view showing the main details of all of the Stack objects in a case can be displayed by double-clicking the Stack collection branch in the Case Navigator or by selecting the Stack collection branch and clicking the Case Navigator View button.

8-3

8-4 Stack View

8.1 Stack View

The following figure shows the Stack view for entering and updating stack data.

NameTextEnter a name to identify this stack object. The entry will be automatically processed to remove any characters that are not allowed in file names.

IgnoredCheck boxClear to include this stack in the calculations or set to ignore this stack when calculating. The effect of setting this check box will be to exclude the stack and all of the tips that are located on it from the calculations.

Figure 8-1, Stack View

8-4

Stacks 8-5

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this stack object is complete and ready for calculation.

Location - Relative ToDrop down list of existing locationsAllows the location of the stack base to be defined relative to another object in the model, for example another stack. If left blank the location is relative to the base point of the model at 0,0,0.

The following fields then define the location of the stack base relative to this location in either Cartesian or polar coordinates.

Location - NorthingRange: -100,000 to 100,000mThe distance of the base of the stack North of the selected reference location. Updates made to this value will automatically update the polar coordinate values.

Location - EastingRange: -100,000 to 100,000mThe distance of the base of the stack East of the selected reference location. Updates made to this value will automatically update the polar coordinate values.

Location - ElevationRange: -100,000 to 100,000mThe height of the base of the stack above or below the selected reference location. Updates made to this value will automatically update the polar coordinate values.

Location - RadiusRange: 0 to 100,000mThe distance to the base of the stack from the selected reference location. Updates made to this value will automatically update the Cartesian coordinate values.

8-5

8-6 Stack View

Location - Angle to HorizontalRange: 0 to 90 The angle to the horizontal of a line from the base of the stack to the selected reference location. Updates made to this value will automatically update the Cartesian coordinate values.

Location - Angle from NorthRange: -0 to 360 The angle from North of a line from the base of the stack to the selected reference location. Updates made to this value will automatically update the Cartesian coordinate values.

Dimensions - LengthRange: 0 to 500mThe centre line length of the stack from the base to the tip support platform. If the stack is selected for sizing this value will be ignored.

Dimensions - Angle to HorizontalRange: 0 to 90The orientation of the stack relative to the horizontal.

Horizontal stacks (0 ) are usually used for liquid flares on offshore platforms. Angled booms (30 , 45 , 60 ) stacks are commonly used for gas flares on offshore platforms. Vertical stacks (90 ) will be used for most onshore installations.

Dimensions - Angle from NorthRange: 0 to 360The orientation of the stack relative to North. Flaresim works on a 360 compass base thus 90 corresponds to a stack or boom pointing due East, 180 to due South etc.

It is important to set the direction of the stack correctly relative to the wind direction since this will have a significant impact on the results. For most design purposes, specifying both the stack angle from North as 0 and wind direction as 0 will give a flame blowing back along the stack axis which will generally give the worst case radiation values for design of the installation.

°

° °

°

°° ° °

°

°

° °°

° °

8-6

Stacks 8-7

Size MeCheck boxSetting this check box automatically selects this stack for a sizing calculation. Note that only one stack can be selected for sizing at a time so this check box will be cleared on all other stacks when it is set. The stack that is currently being sized can be viewed on the Sizing tab of the Calculation Options view.

8-7

8-8 Stack Summary View

8.2 Stack Summary View

The Stack Summary view is shown below. It may be opened by selecting Stack collection branch in the Case Navigator view and clicking the View button or by double-clicking the Stack collection branch.

The Stack Summary view shows the input data and results for all of the stacks in the case. Data input values can be updated through the summary view if required.

Export TableButtonClicking this button opens a File Save dialog to allow the Stacks summary table to be saved as a comma separated value (CSV) file, an Excel format file (XLS) or tab separated text file(TXT).

Figure 8-2, Stack Summary View

8-8

Tips 9-1

9-1

Page

9 Tips

9.1 Tip View. . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

9.1.1 Common Fields . . . . . . . . . . . . . . . . . . . . . . 49.1.2 Details Tab . . . . . . . . . . . . . . . . . . . . . . . . . . 59.1.3 Noise Input Tab . . . . . . . . . . . . . . . . . . . . . 129.1.4 Location & Dimensions Tab . . . . . . . . . . . 149.1.5 Fluids Tab . . . . . . . . . . . . . . . . . . . . . . . . . . 179.1.6 Emissions Tab . . . . . . . . . . . . . . . . . . . . . . 199.1.7 Results Tab . . . . . . . . . . . . . . . . . . . . . . . . . 229.1.8 Noise Results Tab . . . . . . . . . . . . . . . . . . . 249.1.9 Flame Shape Tab . . . . . . . . . . . . . . . . . . . . 269.1.10 Combustion Results Tab . . . . . . . . . . . . . . 289.1.11 Purge Gas Tab . . . . . . . . . . . . . . . . . . . . . . 30

9.2 Size Tip View. . . . . . . . . . . . . . . . . . . . . . . .32

9.3 Tip Summary View . . . . . . . . . . . . . . . . . . .34

9-2

9-2

Tips 9-3

The Tip object allows definition of data to describe each flare tip. A flare tip acts as the disposal point for a single fluid. Multiple flare tips on one or more stacks may be present in a flare system to dispose separately of fluids due to incompatible properties e.g. warm and cold fluids, high and low pressure fluids, dry and wet fluids.

Tip objects may be created using the Add-Tip drop down menu option or by selecting the Tip branch in the Case Navigator view and clicking the Add button.

An existing Tip object may be viewed by double clicking it in the Case Navigator view or by selecting it in the Case Navigator view and clicking the View button.

All defined Tip objects will be included in the calculations unless they have been set to Ignored. A Tip may be set to ignored by selecting it in the Case Navigator view and clicking the Ignore button. An Ignored Tip object can be restored to the calculations by selecting it in the Case Navigator view and clicking the Activate button. Alternatively a Tip object can be ignored and restored by setting or clearing the check box on its view.

A Tip object can be deleted either by clicking the Delete button on its view or by selecting it in the Case Navigator view and clicking the Delete button on this view.

A Tip Summary view showing the main details of all of the Tip objects in a case can be displayed by double-clicking the Tip collection branch in the Case Navigator or by selecting the Tip collection branch and clicking the Case Navigator View button.

9-3

9-4 Tip View

9.1 Tip View

The following figure shows the Tip view for entering and updating tip data.

9.1.1 Common Fields

NameTextEnter text to identify this Tip object.

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this tip object is complete and ready for calculation.

Figure 9-1, Tip Details View

9-4

Tips 9-5

IgnoredCheck box Clear to include this tip in the calculations or set to ignore this tip when calculating.

9.1.2 Details Tab

The Details tab of the Tip view, Figure 9-1, has the following data entry fields.

Details - Tip TypeDrop down list: Pipe / Sonic / Welltest / Combined HP/LPSelects the type of flare tip required. The nature of the fluid being flared through the tip will generally determine the type of tip selected.

For gases, either the pipe or sonic tip types may be selected. Pipe flares are the simplest type of tip and may be specified for both high and low pressure gases. If the pressure available is greater than 2 bar (30 psi) at the tip then a sonic tip can be utilised. Sonic flare tips have the advantage of low flame emissivities due to more efficient combustion of the flare gas. For lower pressures a pipe flare is generally used possibly with steam or air assistance (see 6.2).

Where a combined HP/LP tips is selected the HP tip is assumed to be a sonic tip and the LP a sub-sonic one. The flow ratio of HP to LP fluids should be 3 or greater.

For liquids a Welltest tip type should be selected.

Details - Number of BurnersRange: 1 to 1000 for certain sonic flares otherwise 1The number of individual burners which make up the tip assembly. This should be set to 1 for all tips unless the tip being used produces distinct, separate flames for each burner e.g. the Mardair sonic flare tip or some types of welltest burners.

9-5

9-6 Tip View

Details - Seal TypeDrop down list: None / Fluidic1 / Fluidic2 / Fluidic3 / Molec.1 / Molec.2Defines the type of seal. The riser diameter (see Location and Dimensions tab) and seal type are used solely for calculation of the pressure at the base of the stack. The values calculated are to be used for preliminary review purposes only.

There are two basic types of seal, Fluidic or Molecular:-

Figure 9-2 shows the general design concept for the fluidic seal. The type selection is a function of the opening as defined below

Fluidic1: 50% of total areaFluidic2: 40% of total areaFluidic3: 35% of total area.

Figure 9-2, Fluidic Seal

Opening

Diameter

9-6

Tips 9-7

Figure 9-3 shows the general design concept for the molecular seal. The type selection is a function of the diameter as defined below:-

Molec.1: Traditional design. Maximum diameter is 1.7 times the tip diameter. The pressure drop correlation is based on a design which gives a body length of 5.5m (18ft) regardless of the tip diameter.

Molec.2: Low pressure drop design. Maximum diameter is 2 times the tip diameter. The pressure drop correlation is based on a design which gives a body length which is a function of the tip diameter.

The fluidic seal has a number of advantages over the traditional molecular seal:-

• Lower purge gas requirements and consequent operating costs.• The seal still operates with a high efficiency even if rain water or

chunks of refractory material drop into the baffles. In fact the water is quickly dissipated because the fluidic seal is located at a high temperature section of the flare stack.

• Lower cost due to the simple construction and light weight. A 48" fluidic seal will typically weigh less than half the weight of a 6" molecular seal.

Figure 9-3, Molecular Seal

Diameter

9-7

9-8 Tip View

Radiation Method - MethodDrop down list: Global / Flaresim API / Point / Diffuse / Mixed / Brzustowski / M.Point Brzustowski / Strict API / ChamberlainDefines the methods to be used to calculate the radiation flux at a point for this flare tip. This option is only available for use if the Expert Mode option has been enabled in the Calculation Options view.

It is normal to use the same radiation calculation method for all of the flares in a single model. However there may be occasions when it is desirable to use a particular radiation calculation method for a specific tip. Since the radiation flux from flare tip to a receptor point is always calculated tip by tip and then summed there is no theoretical barrier to using a different radiation method for each tip.

Radiation Method - No. Flame ElementsRange: 1 to 100Defines the number of flame elements to be used to calculate the flame shape for this flare tip. This option is only available for use if the Expert Mode option has been enabled in the Calculation Options view.

Some radiation methods have a requirement for a fixed number of flame elements so this input is not available for all methods.

Radiation Method - Element PositionRange: 0 to 100%

Defines the position within a flame element to be used as the source of the radiation flux. This option is only available for use if the Expert Mode option has been enabled in the Calculation Options view.

This input is not available for all radiation methods. Even where it is possible to update it, this entry should normally be left at its default value of 50%.

F Factor Details - MethodDrop down list: User specified / Natural Gas / Kent / Tan / High Efficiency / Cook / Generic Pipe / Modified Chamberlain / Integrated

9-8

Tips 9-9

Defines the method used to calculate the fraction of the total net heat release from the flame which is radiated. This was labelled emissivity in Flaresim prior to version 1.1. It is also known as the F Factor.

The User specified option allows specification of the value by the user. Otherwise it is calculated by the selected correlation as follows:-

Natural gas: Correlation based on tip exit velocity assuming a natural gas fluid of molecular weight 19.

Tan: Correlation based on mole weight

Kent: Correlation based on mole weight

High Efficiency:Proprietary correlation between tip type, exit velocity, fluid molecular weight and degree of hydrocarbon saturation. Formally known as the Flaresim method in versions prior to 1.2.

Cook: Correlation based on exit velocity.

Generic Pipe: Correlation based on refitting Kent, Tan, Natural gas and Cook methods across a range of exit velocities and molecular weights.

Modified. ChamberlainCorrelation based on mole weight and exit velocity.

Integrated Where a radiation method includes an integrated F Factor calculation. For future use.

Where flare vendor data is available it should be used in preference to a correlation. In the absence of vendor data, the Generic Pipe method is recommended for a conservative design. For clean burning, smokeless flares from well designed flare tips in good condition the High Efficiency method can be used. In practice this means flares burning paraffinic hydrocarbons of low molecular weight fluid (<60) at reasonable exit velocities (> 0.2 mach). For

9-9

9-10 Tip View

fluids other than paraffinic hydrocarbons vendor advice should be sought. In the absence of advice, user specified F Factors of 0.3 to 0.4 are generally reasonable.

Fraction Heat Radiated - Specified/Calculated ValueRange 0.01 to 1.0If the Fraction Heat Radiated Method is set to User Specified then the required value for the fraction of heat radiated must be entered here. Otherwise the calculated result for the selected calculation method will be displayed after the model has been run.

Typical values for different types of flare tip are given in the following table.

Unsaturated hydrocarbons burn with higher quantities of luminescent carbon particles leading to values typically 10-20% greater than for saturated hydrocarbons.

Fraction Heat Radiated - Max ValueRange 0.01 to 1.0Defines the maximum value of the heat radiation fraction to be used for a combined flame and overrides any higher value calculated by a correlation. This field is only visible when the flare tip is a Combined HP/LP type.

Flame Length MethodDrop down list: API / Flaresim / Brzustowski / User Specified / IntegratedThis field selects the method to be used for calculating the length of the flame. This field is only activated when the Expert Mode option is enabled in the Calculation Options view. Otherwise the flame length method will be automatically selected when the Calculation Method is selected in the Calculation Options view.

Tip Type Fraction Heat Radiated

Pipe flare 0.25 to 0.4

Single Burner Sonic 0.10

Multiple Burner Sonic 0.05 to 0.1

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Tips 9-11

The allowed options are:-

API Flame length is calculated from heat released according to equation presented in API 521.

Flaresim Flame length is calculated from heat released using following equation.

where L is flame length in mQ is heat release in J/sN is number of tipsThe constants I1 and I2 take the following values for different tip types.

Brzustowski Flame length is calculated from flammability limits using Brzustowski & Sommer method.

User SpecifiedUser defined constants can be supplied for use with Flaresim equation given above.

Integrated Where the flame length calculation is integrated with the radiation method and it is not appropriate to select an alternative e.g. Chamberlain method.

User MultiplierRange 0 to 2User defined value of constant I1 for flame length equation given above. This entry is only accessible when a User Specified flame length method is selected.

Tip Type I1 I2

Pipe flare 0.00331 0.4776

Single Burner Sonic 0.00241 0.4600

Multiple Burner Sonic 0.00129 0.5000

L I1QN----

I2

=

9-11

9-12 Tip View

User PowerRange 0 to 2User defined value of constant I2 for flame length equation given above. This entry is only accessible when a User Specified flame length method is selected.

9.1.3 Noise Input Tab

The Noise Input tab of the Tip view is shown below.

Combustion Noise - MethodDrop down list: Acoustic Efficiency / Low Noise Reference / Standard Reference / User ReferenceSelects the noise calculation method to be used. The Acoustic efficiency method is described in section 11.3. The other methods are based on a reference spectrum of noise at a known heat release.

Figure 9-4, Noise Input Tab

9-12

Tips 9-13

When the Acoustic Efficiency method is selected the following additional fields are displayed.

Peak FrequencyDrop down list: 62.5, 125, 250, 500, 1000, 2000 HzThis defines the sound frequency band at which the peak noise is generated. The total sound power calculated at this frequency will be distributed across the other sound frequency bands.

EfficiencyRange 1.0e-10 to 1.0%The efficiency at which combustion energy is converted to sound power.

Jet Noise MethodDrop down list: FlaresimThe method used to calculate the jet noise contribution. This is provided for future expansion.

If the Combustion Noise method is set to Standard Reference or Low Noise Reference or User Reference the combustion sound power generated in each frequency band is calculated from a reference value at a reference combustion duty. The Standard Reference and Low Noise Reference data used in the calculation are proprietary data supplied by a flare system vendor.

Selecting a User Reference method displays the Reference Duty and Sound Power Table fields shown in Figure 9-4 above and described below to allow this data to be entered

Figure 9-5, Acoustic Efficiency Data

9-13

9-14 Tip View

Reference. DutyRange: 1 to 1,000 MWDefines the reference heat release corresponding to the sound power data defined in the Sound Power Table.

User Reference SpectrumRange: 1 to 200 dBAllows the user to define the sound power level at each frequency band corresponding to the heat release specified in the Reference Duty field.

9.1.4 Location & Dimensions Tab

Tip Location - On StackDrop down list: Defined stack namesDefines which stack the tip is located on. The drop down list shows the currently defined stacks.

Figure 9-6, Location & Dimensions Tab

9-14

Tips 9-15

Tip Dimensions - LengthRange: 0 to 100mThe physical length of the burner tip. The value is used in calculating the true gas exit point for flame length calculations and gas dispersion calculations.

Note if the length is set to 0m the defined tip angles to horizontal and vertical will still be used to calculate the vector for the fluid jet leaving the tip, not the stack angles.

Tip Dimensions - Angle to HorizontalRange: 0 to 90°The orientation of the tip relative to the horizontal.

Vertical installation of flare tips prevents burn back on the tip and consequent reduction in tip life. The use of inclined tips on inclined booms does have the advantage of directing both the flame and any liquid carryover away from the main platform structure.

Tip Dimensions - Angle from NorthRange: 0 to 360°The orientation of the tip relative to the North.

It is not unusual in offshore flares for the tip to be oriented along a different axis to the boom.

Tip Dimensions - DiameterRange: 0.001 to 10mThe internal diameter of the burner assembly.

For sonic flares the equivalent diameter is calculated for resolution of the fluid jet vectors when calculating the flame shape.

Tip Dimensions - Effective AreaRange: 0.0001 to 100%The actual percentage of the area calculated from the tip diameter which is available for flow of the gas or liquid.

A value of 100% is generally used for pipe flares. For sonic flares the value should be adjusted to ensure that the exit velocity is just

9-15

9-16 Tip View

sonic at the design flare rate. For liquid burners the value should be adjusted to calculate the correct exit velocity.

Tip Dimensions - Riser DiameterRange: 0.001 to 10mThe internal diameter of the pipe from the base of the stack to the tip.

Tip Dimensions - RoughnessRange: 0 to 0.001mThe roughness of the riser to this tip to be used in calculating the riser pressure drop.

Tip Exit Settings - Contraction CoefficientRange: 0.01 to 1.0The ratio of the diameter of the vena contractor to the diameter of the discharge orifice (tip). If not specified this will be calculated and the result displayed on the Results tab.

Tip Exit Settings - Exit Loss CoefficientRange: 1 to 1000The number of velocity heads which defines the exit loss for the tip. For a sonic tip the value should always be 1.0. Note that if the exit loss coefficient is specified the outlet pressure field cannot also be specified.

Tip Exit Settings - Outlet PressureRange: 10 to 10,000kPaThe static pressure at the outlet of the tip, i.e at the point where the fluid emerges from the tip. Normally this will be calculated and displayed on the results tab. If specified the exit loss coefficient must be left unspecified and will be calculated.

The tip exit pressure is used to calculate the properties of the gas at the exit and hence the velocity of the fluid.

Calculate Burner OpeningCheck boxSelection of the Calculate Burner Opening check box causes will result in the burner opening of a sonic tip being adjusted until the tip exit velocity is just sonic.

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Tips 9-17

Size MeButtonThe Size Me button opens a pop up window to allow the diameter of the tip to be sized for a specific exit velocity, optionally using standard pipe sizes. See section 9.2 for details.

9.1.5 Fluids Tab

Primary Fluid - NameDrop down list: Defined FluidsAllows one of the defined fluids in your model to be assigned to the flare tip

Primary Fluid - Mass FlowRange: 0 to 10,000 kg/sThe mass flow rate of the fluid fed to this tip. The molar flow entry will be updated automatically.

Figure 9-7, Fluids Tab

9-17

9-18 Tip View

Primary Fluid - Mole FlowRange: 0 to 10,000 kgmole/sThe molar flow rate of the fluid fed to this tip. The mass flow entry will be updated automatically.

The following Secondary Fluid entries will be visible if the selected Tip type is set to Combined HP/LP.

Secondary Fluid - NameDrop down list: Defined FluidsAllows one of the defined fluids in your model to be assigned to LP flare tip of a Combined HP/LP tip.

Secondary Fluid - Mass FlowRange: 0 to 10,000 kg/sThe mass flow rate of the fluid fed to the LP tip of a Combined HP/LP tip. The molar flow entry will be updated automatically.

Secondary Fluid - Mole FlowRange: 0 to 10,000 kgmole/sThe molar flow rate of the fluid fed to the LP tip of a Combined HP/LP tip. The mass flow entry will be updated automatically.

Assist Fluid - NameDrop down list: Defined Assist FluidsAllows one of the defined assist fluids in your model to be assigned to this flare tip.

Assist Fluid - Mass FlowRange: 0 to 10,000 kg/s or CalculatedDefines the flow of assist fluid to the tip. When the assist fluid has been set to Smokeless Operation then this value will be calculated. Otherwise either this value or the ratio must be specified.

Assist Fluid - Flow RatioRange: 0 to 100 or CalculatedThe ratio of assist fluid to fluid being flared. When the assist fluid has been set to Smokeless Operation then this value will be calculated. Otherwise either this value or the flow must be specified.

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Tips 9-19

Combustion Input - Air RatioRange: 1 to 10This is the ratio of combustion air drawn into the flame to the stoichiometric quantity of air required for complete combustion. It should not include any air added as an assist fluid. Typical values might be 2.0 to 3.0.

The value is used in the calculation of the flame temperature.

Combustion Gases - Flame TemperatureRange 0 to 5000 K or CalculatedThis is the temperature of the flame that will be used to calculate the transmission of radiation through water shields and in gas dispersion calculations for the combustion gases. If the value is left blank it will be calculated from the heat of combustion and the specified combustion air ratio.

9.1.6 Emissions Tab

The view above shows the default view of the Emissions tab of the Tip Object. By default the emissions data for a case is defined for all tips on the Emissions page of the Calculation Options view.

Figure 9-8, Emissions Tab Default

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9-20 Tip View

If the Expert Mode option is set on the General tab of the Calculation Options view then the emissions input data can be updated on a tip by tip basis and the view will change to the one shown below.

NOx Emission - BasisDrop down list: Mass/Heat Release / Mass/Mass Flared Fluid / Mass/Moles Flared Fluid / Sintef MethodThis field defines the basis used to calculate the NOx emission rate. This is either as a ratio to the heat released by the flare, the mass of flared fluid or the moles (volume) of flared fluid. Alternatively it can be calculated by the Sintef method as a function of exit velocity and tip diameter as described in the Methods chapter.

NOx Emission - RateRange depends on basisThe generation rate for NOx emissions for the defined basis.

Figure 9-9, Emissions Tab Data Input

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Tips 9-21

CO Emission - BasisDrop down list: Mass/Heat Release / Mass/Mass Flared Fluid / Mass/Moles Flared FluidThis field defines the basis used to calculate the CO emission rate. This is either as a ratio to the heat released by the flare, the mass of flared fluid or the moles (volume) of flared fluid.

CO Emission - RateRange depends on basisThe generation rate for CO emissions for the defined basis.

Unburnt HC Emission - BasisDrop down list: Mass/Heat Release / Mass/Mass Flared Fluid / Mass/Moles Flared FluidThis field defines the basis used to calculate the unburnt hydrocarbon emission rate. This is either as a ratio to the heat released by the flare, the mass of flared fluid or the moles (volume) of flared fluid.

Unburnt HC Emission - RateRange depends on basisThe generation rate for unburnt hydrocarbon emissions for the defined basis.

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9-22 Tip View

9.1.7 Results Tab

Exit Properties - VelocityCalculated ValueThe calculated exit velocity from this flare tip.

Exit Properties - Mach NumberCalculated ValueThe calculated exit velocity from this flare tip expressed as a Mach number.

Exit Properties - Volume FlowCalculated ValueThe volume flow rate of the fluid leaving the tip at the tip conditions.

Exit Properties - Contraction CoefficientCalculated ValueThe calculated contraction coefficient.

Figure 9-10, Results Tab

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Tips 9-23

Exit Properties - Exit TemperatureCalculated ValueThe calculated fluid exit temperature.

Flame Results - Heat ReleaseCalculated ValueThe total heat released by the flame from this flare tip.

Flame Results - Flame LengthCalculated ValueThe flame length calculated for the tip and used to determine the flame’s position for the radiation calculations. For a Pipe flare this will be the same as the API Flame Length. For Sonic flares the flame length will normally be significantly less than the API value.

Flame Results - API LengthCalculated ValueThe length of the flame calculated using the method outlined in API RP521. The method assumes a pipe flare.

Pressure Profile - TableCalculated ValuesThe pressure profile results table shows the calculated static and total pressures from the tip exit through to the base of the stack. The table also includes the pressure drop across the tip, seal and stack.

The Total pressure reported is the static pressure plus the pressure resulting from the fluids momentum.

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9-24 Tip View

9.1.8 Noise Results Tab

Total Noise - SPLCalculated ValueThe sound pressure level calculated summing the individual contributions at the different frequencies.

Total Noise - Ref DistanceCalculated ValueDisplays the reference distance at which the sound pressure level is calculated. It is a fixed value and cannot be changed.

DisplayDrop down list: Table / PlotSelects whether the noise spectrum results are displayed as a table or as a graph.

Figure 9-11, Noise Results Tab

9-24

Tips 9-25

Noise SpectrumCalculated ValuesThis table or graph shows the noise generated as a function of the sound frequency. The results show the contribution from combustion noise and jet noise as well as the total noise at each defined frequency.

ExportButtonAllows the noise spectrum data to be saved. If the noise spectrum is currently displayed as a table, a standard file dialog box will be displayed to allow the data to be saved as an Excel XLS file or a comma separated CSV file. If the data is displayed as a plot it may be saved as a graphics file. A standard file dialog box will appear to allow the name and file type to be entered. The allowed file types are JPG, PNG, BMP, WMF or EMF.

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9-26 Tip View

9.1.9 Flame Shape Tab

End of Tip - NorthingCalculated Value The distance north of the end of this tip from the origin.

End of Tip - EastingCalculated Value The distance east of the end of this tip from the origin.

End of Tip - ElevationCalculated Value The height of the end of this tip relative to the origin.

Figure 9-12, Flame Shape Tab

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Tips 9-27

DisplayDrop down list: Table / 3D Plot / 2D Plot - North vs. East / 2D Plot - North vs. Elevation / 2D Plot - East vs. ElevationAllows selection of the display method for the flame shape results.

The flame shape is calculated using the calculation method and number of elements specified by the user in the Calculation Options view.

ExportButtonAllows the flame shape data to be saved to an external file. If the data is displayed as a table it may be saved to an Excel XLS file or a comma separated CSV file. If it is displayed as a plot, the data may be saved to a JPG, PNG, BMP, WMF or EMF graphics file. In either case a standard file dialog box will appear to allow the name and file type to be entered.

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9-28 Tip View

9.1.10 Combustion Results Tab

Flame Temperatures - Adiabatic Flame TempCalculated ValueThe flame temperature calculated by combustion of the fluid at the combustion air ratio defined on the fluids tab. Any air assist fluid flow is in addition to the combustion air. The adiabatic temperature calculation assumes no radiant heat losses from the flame.

Flame Temperatures - Calculated Flame TempCalculated ValueThe flame temperature calculated by combustion of the fluid after allowing for heat loss from the flame due to radiation. The F Factor calculated or defined on the Details tab is used to calculate the heat loss due to radiation. The calculation is based on the combustion air ratio defined on the fluids tab with any air assist fluid flow being an addition to the combustion air.

Figure 9-13, Combustion Results Tab

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Tips 9-29

Combustion Gases - Mass FlowCalculated ValuesThis table presents the calculated combustion gas mass flows. There are three types of combustion gas result presented.

The basic combustion gases, CO2, H2O and others such as SO2 are calculated directly from the defined fluid composition. The number of each type of atom in each component is defined in their structure in the component database. The combustion products for each atom type are in the component library and this is used to determine the quantity of combustion gases generated. Any additional steam assist fluid is added to the quantity of H2O present.

In the event that a flared fluid is defined by bulk properties data, a composition is derived from the defined mole weight. Essentially the composition is assumed by selecting the two straight chain hydrocarbon components, C1 through C10 from the data base that have mole weights immediately lower than and higher than the specified mole weight. The proportion of these two components is then calculated to provide a fluid with the same mole weight.

The air components O2 and N2 are calculated based on the combustion air ratio and assist air if any.

Finally the emissions components NO, CO and unburnt hydrocarbon which is expressed as CH4 are calculated according to the emissions data provided on the Emissions tab of the Tip object or the global emissions data provided on the Emissions tab of the Calculation Options object.

Combustion Gases - Mole FlowCalculated ValuesThis table presents the calculated combustion gas molar flows. These are derived from the mass flows using a simple mole weight conversion.

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9-30 Tip View

9.1.11 Purge Gas Tab

Purge Input Data - Purge FluidDrop down list of allowed purge fluidsThis selects the purge fluid that is to be used. The list displays all of the fluids defined in the case together with Nitrogen and Methane.

Purge Input Data - Fixed VelocityRange 0 to 10 m/sThis defines a fixed purge velocity that is to be maintained. The flow of purge gas required to give this velocity will be calculated.

Purge Input Data - Fixed FlowRange 0 to 10 m3/sThis defines a fixed volumetric purge flow rate that is to be maintained. The purge gas velocity and mass flow rate required to meet this target will be calculated.

Purge Input Data - HUSA O2Range 0 to 100%This defines the percentage of oxygen that is to be used in the full HUSA method calculation for purge gas flow see methods chapter.

Figure 9-14, Purge Gas Tab

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Tips 9-31

The default value of 6% is suggested in HUSA’s papers as being generally appropriate for hydrocarbon flare gas fluids with molecular weights of methane and above.

Purge Input Data - HUSA HeightRange 0 to 500 mThis defines the distance from the top of the stack in the full HUSA method calculation for purge gas flow. The default value of 25 ft is suggested in HUSA’s papers (see methods chapter for references) as an acceptable value that will reduce the quantity of purge gas required without leading to an unsafe condition. Note that this default does assume that it is acceptable to have a potentially explosive mixture in the top 25ft of the flare stack.

Purge Results - TableCalculated ResultsThis table shows the purge gas velocities and mass flows calculated by the different purge gas methods.

Note that all calculations are based on the stack diameter not the tip diameter using purge gas properties calculated at the temperature and pressure defined for the currently selected environment.

Update Purge CalcsButtonClicking this button causes the purge gas calculations to be updated for the current tip without recalculating the entire Flaresim case.

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9-32 Size Tip View

9.2 Size Tip View

The Size Tip view appears when the Size Me button on the Location & Dimensions tab of the Tip view is selected. The Size Tip view is modal and must be closed before you can interact with other Flaresim views.

Fluid Data - Mass FlowRange 0 to 10,000 kg/sThis field defines the mass flow that the tip is to be sized for. The value specified here will default to the value entered on the Fluids tab of the Tip view. If changed and the Ok button is used to exit the Size Tip view the mass flow on the Fluids tab will be updated.

Fluid Data - Mole FlowRange 0 to 10,000 kgmole/sThis field defines the molar flow that the tip is to be sized for. The value specified here will default to the value entered on the Fluids tab of the Tip view. If changed and the Ok button is used to exit the Size Tip view the molar flow on the Fluids tab will be updated.

Fluid Data - Mach NumberRange 0 to 1This field defines the Mach Number that the tip is to be sized for. Alternatively if the Tip Diameter is specified the Mach Number will be calculated and displayed here.

Figure 9-15

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Tips 9-33

Diameter Data - Use Nominal DiametersDrop down list: Yes / NoSet this to Yes to constrain the tip diameters selected to those appropriate for nominal pipe diameters.

Diameter Data - Tip DiameterRange 0.001 to 10mThe diameter of the tip. If Mach Number is specified then the calculated tip diameter is displayed here. Otherwise the tip diameter can be specified to calculate the Mach Number.

Note this field will be inactive when the Use Nominal Diameter setting is Yes.

Nominal Diameter

List box: Nominal pipe diameters for STD schedule pipesThis list box can be used to select the nominal diameter for the Tip assuming that it is a STD schedule pipe. The actual diameter will then be set by look up from the nominal diameter.

Note selection of Nominal Diameter will only be active when the Use Nominal Diameter setting is Yes.

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9-34 Tip Summary View

9.3 Tip Summary View

The Tip Summary view is shown below. It may be opened by selecting Tip collection branch in the Case Navigator and clicking the View button or by double-clicking the Tip collection branch.

The Tip Summary view provides a view of the main input data items and results for all of the Tips in a case. Input data items can be updated through the summary view.

Export TableButtonClicking this button opens a File Save dialog to allow the Environments summary table to be saved as a comma separated value (CSV) file, an Excel file (XLS) or tab separated text file (TXT).

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Receptors 10-1

10 Receptors

Page10.1 Receptor Point View . . . . . . . . . . . . . . . . . .4

10.1.1 Common Fields . . . . . . . . . . . . . . . . . . . . . . 410.1.2 Point Definition Tab . . . . . . . . . . . . . . . . . . . 510.1.3 Point Properties Tab . . . . . . . . . . . . . . . . . . 810.1.4 Point Results Tab. . . . . . . . . . . . . . . . . . . . .1110.1.5 Noise Results . . . . . . . . . . . . . . . . . . . . . . . 1210.1.6 Wind Rose Results. . . . . . . . . . . . . . . . . . . 13

10.2 Receptor Point Summary View . . . . . . . . .17

10.3 Receptor Grid View . . . . . . . . . . . . . . . . . .18

10.3.1 Common Fields . . . . . . . . . . . . . . . . . . . . . 1810.3.2 Grid Extent Tab. . . . . . . . . . . . . . . . . . . . . . 1910.3.3 Grid Radiation Tab . . . . . . . . . . . . . . . . . . . 2110.3.4 Grid Noise Tab . . . . . . . . . . . . . . . . . . . . . . 2210.3.5 Grid Temperature Tab . . . . . . . . . . . . . . . . 2410.3.6 Grid Concentration Tab . . . . . . . . . . . . . . . 2510.3.7 Grid Maximum Radiation Tab . . . . . . . . . . 2610.3.8 Grid Plot Overlay Tab. . . . . . . . . . . . . . . . . 2710.3.9 Grid Graphic Report Tab . . . . . . . . . . . . . . 31

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Receptors 10-2

Page

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Receptors 10-3

Receptors are the points at which Flaresim will calculate the thermal radiation, noise and surface temperatures resulting from the operation of one or more flare tips. Flaresim provides the ability to define Receptor Point objects which define a single point for the calculations and Receptor Grid objects which define a rectangular set of points in a plane.

Receptor Point objects may be created using the Add-Receptor Point drop down menu option or by selecting the Receptor Points branch in the Case Navigator view and clicking the Add button.

An existing Receptor Point object may be viewed by double clicking it in the Case Navigator view or by selecting it in the Case Navigator view and clicking the View button.

Receptor Point objects will be calculated unless they have been set to Ignored. A Receptor Point may be set to ignored by selecting it in the Case Navigator view and clicking the Ignore button.or restored to the calculations clicking the Activate button. Alternatively a Receptor Point object can be ignored and restored by setting or clearing the check box on its view.

A Receptor Point object can be deleted either by clicking the Delete button on its view or by selecting it in the Case Navigator view and clicking the Delete button on this view.

A Receptor Point Summary view provides a summary of all the Receptor Points in a model. It can be opened by double clicking the Receptor Points branch in the Case Navigator.

Receptor Grid objects may be created using the Add-Receptor Grid drop down menu option. A Receptor Grid can be deleted using the Delete button on its view. Alternatively a Receptor Grid can be created, viewed or deleted using the Case Navigator view in the usual way.

Like receptor points, Receptor Grid objects will be calculated unless they have been set to Ignored. Receptor Grid objects can be ignored and restored though the check box on the Receptor Grid view or through the Case Navigator view.

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10-4 Receptor Point View

10.1 Receptor Point View

The following figure show the Receptor Point view for entering and updating stack data.

10.1.1 Common Fields

NameTextEnter text to identify this Receptor Point object.

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this Receptor Point object is complete and ready for calculation.

Figure 10-1, Receptor Point View

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Receptors 10-5

IgnoredCheck boxClear to calculate the results for this Receptor Point or set to ignore this point when calculating.

10.1.2 Point Definition Tab

The Definition tab of the Receptor Point view, see Figure 10-1, has the following data entry fields.

Location - Relative ToDrop down list of existing locationsAllows the location of the receptor point to be defined relative to another object in the model, for example the base of a stack. If left blank the location is relative to the origin point of the model at 0,0,0.

The following fields then define the location of the stack base relative to this location in either cartesian or polar coordinates.

Cartesian Coordinates - NorthingRange: -100,000 to 100,000mThe distance of the receptor point North of the selected reference location. Updates made to this value will automatically update the polar coordinate values.

Cartesian Coordinates - EastingRange: -100,000 to 100,000mThe distance of the receptor point East of the selected reference location. Updates made to this value will automatically update the polar coordinate values.

Cartesian Coordinates - ElevationRange: -100,000 to 100,000mThe distance of the receptor point above or below the selected reference location. Updates made to this value will automatically update the polar coordinate values.

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Polar Coordinates - RadiusRange: 0 to 100,000mThe distance to the receptor point from the selected reference location. Updates made to this value will automatically update the cartesian coordinate values.

Polar Coordinates - Angle to HorizontalRange: 0 to 90 The angle to the horizontal of a line from the receptor point to the selected reference location. Updates made to this value will automatically update the polar coordinate values.

Polar Coordinates - Angle from NorthRange: 0 to 360 The angle from North of a line from the receptor point to the selected reference location. Updates made to this value will automatically update the polar coordinate values.

Sizing Constraints - RadiationRange: 0 to 100,000 W/m2The maximum thermal radiation to be allowed at this point when performing sizing calculations.

The following table provides typical values for design levels of radiation at different locations.

Design Radiation

W/m2Conditions

15,780 On structures and in areas where operators are not likely to be performing duties and where shelter from radiant heat is available e.g. behind equipment.

9,470 At design flare release at any location to which personnel have access e.g. at grade below the flare or on a service plat-form of a nearby tower. Exposure must be limited to a few seconds, sufficient for escape only.

6,310 In areas where emergency actions lasting up to 1 minute may be required by personnel without shielding but with appropriate clothing.

°

° °

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Receptors 10-7

Sizing Constraints - SPLRange: 60 to 200 dBThe maximum sound pressure level to be allowed at this point when performing sizing calculations.

Sizing Constraints - SPLARange: 60 to 200 dBAThe maximum A-weighted sound pressure level to be allowed at this point when performing sizing calculations.

Sizing Constraints - Average SPLRange: 60 to 200 dBThe maximum average sound pressure level to be allowed at this point when performing sizing calculations.

Sizing Constraints - Max TemperatureRange: 100 to 600 KThe maximum temperature to be allowed at this point when performing sizing calculations.

Observed Values - RadiationRange: 0 to 100,000 W/m2This field allows observed values of radiation at this receptor point to be defined so that they can be used by the F Factor fitting process. See Calculations chapter.

4,730 In areas where emergency actions lasting several minutes may be require by personnel without shielding but with appropriate clothing.

1,890 At design flare release on the helideck of an offshore plat-form. This value is suggested by the Civil Aviation Author-ity where the helicopter rotors are stationary. If the rotors

remain turning then a limit of 4,730 W/m2 can apply.

1,390 At design flare release at any location where personnel are continuously exposed.

Design Radiation

W/m2Conditions

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10.1.3 Point Properties Tab

Point Properties - EmissivityRange: 0.0001 to 1.0The emissivity of the point which will be used in the heat balance calculations to determine surface temperature. The emissivity is used to calculate the radiative heat loss from the receptor point.

A typical value for steel is 0.7.

Point Properties - AbsorbtivityRange: 0.0001 to 1.0The absorbtivity of the point which will be used in the heat balance calculations to determine surface temperature. It is the fraction of the radiation incident on the point that will be absorbed. A typical value for steel is 0.7.

Figure 10-2, Receptor Point Properties Tab

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Receptors 10-9

Point Properties - Area RatioRange: 0.0001 to 10,000The ratio of the area available to allow the receptor to lose heat to the area of the receptor exposed to the thermal radiation.

A plate with one face exposed to a flare would have an Area Ratio of 2.0.

Point Properties - MassRange: 0 to 1,000,000 kgThe mass at the point to be used in the calculation of the rate of surface temperature rise.

Properties - Mass CpRange: 0.1 to 10,000 J/kg/K The mass specific heat capacity of the material at the point to be used in the calculation of the rate of surface temperature rise.

Properties - Initial TemperatureRange: 10 to 1000 KThe initial temperature of the receptor point.

On PlaneDrop down list: None / Northing-Easting / Northing-Elevation / Easting-Elevation / Maximum / User DefinedThis entry sets the orientation of the receptor point and it is used to calculate the angle of incidence of the thermal radiation on the receptor.

The default setting is None which means that no correction for angle of incidence will be applied and the full radiation falling on the point at any angle will be calculated. This is the most conservative option.

The other options are only active when the Expert Mode option is set in the Calculation Options view.

Setting On Plane to Northing-Easting, Northing-Elevation or Easting-Elevation sets the point to lie in that plane. Setting the On Plane entry to Maximum will cause Flaresim to iterate on the receptor plane angle to find the angle of maximum radiation. This is not the same as None since with a multiple element flame or

Incident radiation

Heat Loss

E.g. A plate would have anarearatio of 2.0.

10-9


multiple tips radiation will strike the receptor at varying angles leading to a reduced total radiation. This option can require significant calculation time.

Selecting the final option, User Defined, will display the following table to allow the angle of the receptor point plane to be defined.

Receptor Plane - Rotation about East - WestRange: 0 to 360The angle of the receptor point plane to the East - West axis.

Receptor Plane - Rotation about ElevationRange: 0 to 360The angle of the receptor point plane to the Elevation axis.

Changing the setting of the receptor point plane angle can significantly reduce the radiation result for a point when compared to the default setting of None. Whether it is appropriate to change this setting will depend on the nature of the point and the radiation constraint being considered.

For example if the radiation constraint is for personnel exposure it would be less appropriate to change the setting since people are mobile and “rounded” and so effectively receive radiation from multiple directions. If the constraint is for a fixed structure in a known orientation however it would be more appropriate to set the receptor plane orientation.

As always it is the engineer’s judgement to make the appropriate selection.

Figure 10-3, Receptor Point Plane Angle

° °

° °

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Receptors 10-11

10.1.4 Point Results Tab.

Thermal Results - RadiationCalculated ValueThe calculated thermal radiation received at the point from all of the flares in operation.

Thermal Results - TemperatureCalculated Value The equilibrium surface temperature reached during prolonged flaring.

Thermal Results - ConcentrationCalculated Value The concentration of gas at this point due to jet dispersion of relieving fluid in flame out conditions. Note that the jet dispersion calculations have a lower concentration cut off defined on the

Figure 10-4, Point Results Tab

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Emissions tab of the Calculation Option view and that concentrations below this cut off will be reported as 0.

Temperature Profile - DisplayRadio buttons: Table / PlotSelects whether the calculated change in temperature of the receptor point with time is displayed as a table or as a graph.

ExportButtonAllows the calculated curve of time vs. point temperature to be exported to a file. If the data is displayed as a table it may be exported to an Excel XLS file or a comma separated CSV file. If displayed as a graph it may be exported to a JPG, PNG, BMP, WMF or EMF graphics file. In either case a standard file dialog box will appear to allow the name and file type to be entered.

10.1.5 Noise Results

Figure 10-5, Noise Results

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Receptors 10-13

SPLCalculated ValueThe total sound pressure level at the receptor point. It is calculated by summing the sound pressure contributions at each frequency.

SPLACalculated ValueThe A-weighted sound pressure level calculated at the receptor point. It is calculated by summing the A-weighted sound pressure levels at each frequency.

Average SPLCalculated ValueThe sound pressure level averaged across all the frequencies.

DisplayRadio Buttons Table / PlotSelects whether the sound pressure levels vs. frequency results are displayed as a table or as a graph.

ExportButtonAllows the calculated sound pressure vs. frequency results to be exported to a file. If the data is displayed as a table it may be exported to an Excel XLS file or a comma separated CSV file. If displayed as a graph it may be exported to a JPG, PNG, BMP, WMF or EMF graphics file. In either case a standard file dialog box will appear to allow the name and file type to be entered.

10.1.6 Wind Rose Results

The Wind Rose Results tab shown below displays the results of wind rose calculations. Wind Rose calculations show the radiation received at a receptor point for a range of wind directions and speeds as defined on the Wind Rose tab of the active Environment. If no wind rose results are available a message stating this will be displayed.

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DisplayDrop down list: Table / PlotThis controls whether the results from the wind rose calculations are displayed as a plot or as a table of results. The view will update to show the results in the format requested.

Export ButtonAllows the calculated wind rose results to be exported to a file. If the data is displayed as a table it may be exported to an Excel XLS file or a comma separated CSV file. If displayed as a graph it may be exported to a JPG, PNG, BMP, WMF or EMF graphics file. In either case a standard file dialog box will appear to allow the name and file type to be entered.

Figure 10-6, Wind Rose Results

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Receptors 10-15

ButtonThis opens a standard file open dialog to allow selection of the layout file for the graphical report of the wind rose plot.

Layout file for graphical reportFilenameThis defines the name of the graphic report layout file that will be used to generate the graphic report for this receptor point wind rose. The default value set when the Receptor Point is created is defined in the Files tab of the Preferences view.

Layout files describe the background text, data items and graphics formatting instructions required to define a graphics report in an XML formatted file with the extension .LAY.

Standard layout files are shipped with Flaresim to provide graphic report definitions for 1 and 2 stack systems with 1 or 2 tips on A4 and Letter paper sizes. Appendix A describes the structure and the elements that make up a layout file.

Generate Graphic ReportButtonThis creates a new graphical report window to display the wind rose results in a graphical report alongside selected data items for the model. The layout of this report is controlled by the layout file selected. The graphic report is displayed in its own window and by default is displayed as a maximised view. The graphic report window can be minimised, resized and closed using standard windows methods. A sample is shown below.

10-15


Wind rose graphic reports can be printed using the File - Print Graphic Report menu item.

Figure 10-7, Wind Rose Graphic report

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Receptors 10-17

10.2 Receptor Point Summary View

The Receptor Point Summary view is shown below. It may be opened by clicking the Receptor Point branch of the Case Navigator view and then clicking the View button.

This summary view for the defined Receptor Points allows easy comparison and update of the data input values and review of the results across all the points.

Export TableButtonClicking this button opens a File Save dialog to allow the Receptor Points summary table to be saved as a comma separated value (CSV) file. Files of this data type can be opened easily using Excel or other applications.

Figure 10-8, Receptor Point Summary View

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10-18 Receptor Grid View

10.3 Receptor Grid View

The Receptor Grid view is shown below.


NameTextEnter text to identify this Receptor Grid object.

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this Receptor Grid object is complete and ready for calculation.

Figure 10-9, Receptor Grid View

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Receptors 10-19

IgnoredCheck boxClear to calculate the results for this Receptor Grid or set to ignore this grid when calculating.

10.3.2 Grid Extent Tab

The Grid Details tab of the Receptor Grid view, see Figure 10-9. has the following data entry fields.

Grid Extent - Grid PlaneDrop down list: Northing-Easting / Northing - Elevation / Easting - ElevationThis set of radio buttons selects the orientation plane of the receptor grid. Receptor grids are set up for one of the three orthogonal planes. In Flaresim terminology, the X-Y plane is Northing-Easting, the X-Z plane is Northing-Elevation and the Y-Z plane is Easting-Elevation.

Once selected the other fields are used to define the receptor grids location and extent and the fineness or coarseness of the grid. The names of these fields will be updated appropriately. For example when the orientation is set to Northing-Elevation, the offset field will be titled Easting Offset, the next group of fields will be titled Northing and the next block Elevation.

Grid Extent - OffsetRange: -10,000 to 10,000 mThe offset of the receptor grid plane from the model origin.

MinimumRange: -10,000 to 10,000 mThe minimum extent of the grid in the labelled direction.

MaximumRange: -10,000 to 10,000 mThe maximum extent of the grid in the labelled direction.

10-19


Number of PointsRange: 1 to 1001The number of increments that the distance between the minimum and maximum extents will be divided into.

Properties - On PlaneDrop down list: None / Northing-Easting / Northing-Elevation / Easting-Elevation / MaximumThe orientation of the receptor and is used to determine the correction to be applied due to the angle of incidence of the receptor to the flare. This option is only active when the Expert Options check box is set in the Calculation Options view.

With the default setting of receptor point orientation to None no correction for angle of incidence will be applied. This is the most conservative option.

Setting the receptor point orientation to Maximum will reduce the speed of calculations significantly.

Receptor Properties - EmissivityRange: 0.0001 to 1The emissivity of each point in the grid which will be used in the heat balance calculations to determine surface temperature.

Typical value for steel is 0.7

Receptor Properties - AbsorbtivityRange: 0.0001 to 1.0The absorbtivity of each point in the grid which will be used in the heat balance calculations to determine surface temperature. This is defined as the fraction of thermal radiation striking a surface that will be absorbed.

Typical value for steel is 0.7.

Receptor Properties - Area RatioRange: 0.0001 to 10,000The ratio of the area of the receptor available for losing heat to the area of the receptor exposed to the flare. For a flat plate with one face exposed to the flare the Area Ratio would be 2.0.

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Receptors 10-21

Options - Noise BasisDrop down list: Noise / NoiseA / AverageNoiseThis entry defines whether the noise results calculated for the Receptor Grid are the Noise sound power level, the A-weighted sound power level or the Average sound power level.

Receptor Grids in versions of Flaresim prior to 3.0 automatically calculated Noise sound power.

Find Maximum RadiationCheck boxWhen set Flaresim will perform a calculation to find the point of maximum radiation within the plane defined by for this Receptor Grid. The search is carried out using a Nelder & Mead type algorithm and the calculated results will be displayed in the Max Radiation Tab.

10.3.3 Grid Radiation Tab

The Radiation tab of the Receptor Grid view displays a table or a plot of the calculated thermal radiation at each point in the grid as shown in Figure 10-10 below.

DisplayDrop down list: Table / PlotSelects whether the thermal radiation results are displayed as a table or as a graph.

When a new Receptor Grid is created the graph display settings are set to the defaults defined in the Preferences View, see section 5.4. They may then be modified by using the Zoom and Customise buttons as described in chapter 13.

ExportButtonAllows the calculated thermal radiation results to be exported to a file. If the data is displayed as a table it may be exported to an Excel XLS file or a comma separated CSV file. If displayed as a graph it may be exported to a JPG, PNG, BMP, WMF or EMF graphics file.

10-21


In either case a standard file dialog box will appear to allow the name and file type to be entered.

10.3.4 Grid Noise Tab

The Noise tab of the Receptor Grid view displays a table or a graph of the sound pressure at each point in the grid. The value displayed will be the Noise, A-weighted Noise or Average Noise as specified on the Extent tab.

Figure 10-10, Grid Radiation Tab

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Receptors 10-23

DisplayDrop down: Table / PlotSelects whether the sound pressure results are displayed as a table or as a graph.


ExportButtonAllows the calculated sound pressure results to be exported to a file. If the data is displayed as a table it may be exported to an Excel XLS or comma separated CSV file. If displayed as a graph it may be exported to a JPG, PNG, BMP, WMF or EMF graphics file. In either

Figure 10-11, Grid Noise Tab

10-23


case a standard file dialog box will appear to allow the name and file type to be entered.

10.3.5 Grid Temperature Tab

The Temperature tab of the Receptor Grid view displays a table or a graph of the calculated final surface temperatures at each point in the grid.

DisplayDrop down list: Table / PlotSelects whether the temperature results are displayed as a table or as a graph.

When a new Receptor Grid is created the graph display settings are set to the defaults defined in the Preferences View, see section 5.4.

Figure 10-12, Grid Temperature Tab

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Receptors 10-25

They may then be modified by using the Zoom and Customise buttons as described in chapter 13.

ExportButtonAllows the calculated temperature results to be exported to a file. If the data is displayed as a table it may be exported to an Excel XLS file or a comma separated CSV file. If displayed as a graph it may be exported to a JPG, PNG, BMP, WMF or EMF graphics file. In either case a standard file dialog box will appear to allow the name and file type to be entered.

10.3.6 Grid Concentration Tab

The Receptor Grid, Concentration tab shows the results of the jet dispersion calculations as shown below.

Figure 10-13, Grid Concentration Tab

10-25


The jet dispersion results are only available when the jet dispersion calculations are enabled in the Calculation Options view.

DisplayDrop down list: Table / PlotSelects whether the concentration results are displayed as a table or as a graph.


ExportButtonAllows the calculated concentration results to be exported to a file. If the data is displayed as a table it may be exported to an Excel XLS file or a comma separated CSV file. If displayed as a graph it may be exported to a JPG, PNG, BMP, WMF or EMF graphics file. In either case a standard file dialog box will appear to allow the name and file type to be entered.

10.3.7 Grid Maximum Radiation Tab

The Maximum Radiation tab shows the results of the search for the point of maximum radiation within the grid.

Figure 10-14, Grid Maximum Radiation Tab

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Receptors 10-27

Maximum Radiation Results - RadiationCalculated ResultThe maximum value of radiation found within the Receptor Grid.

Maximum Radiation Results - Location 1Calculated ResultThe location of the point of maximum radiation within the Receptor Grid, Axis 1.

Maximum Radiation Results - Location 2Calculated ResultThe location of the point of maximum radiation within the Receptor Grid, Axis 2.

10.3.8 Grid Plot Overlay Tab

The Plot Overlay tab of the Receptor Grid view allows the user to select and define an overlay drawing that will appear as the background picture in the various isopleth plots.

File TypeRadio buttons: Use External Overlay File / Use Flaresim Overlay Two types of overlay file may be used.

An external file can be selected. In this case the extents or dimensions of the drawing must be specified together with the location of the Flaresim coordinate origin within the drawing.

Alternatively a background overlay picture can be created as an Overlay object within Flaresim.

In both cases there is a limit to the complexity of drawings that can be managed by the graphics component that Flaresim uses to generate isopleth plots. If isopleth results must be integrated with detailed plot drawings it is suggested that the isopleth results are exported as a DXF script through the File - Print Graphic Reports view, see chapter 15. This script will allow accurate integration of the isopleth results with a plot plan using external software.

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External File Type

When the File Type is set to Use External Overlay file the options are as shown below.

File Type - NameFile name stringThis entry defines the external graphics file that will be used as a background picture for this Receptor Grids isopleth plots. Only a reference to the file is stored within the Flaresim case so the specified file must be copied separately when moving or transmitting Flaresim case files.

BrowseButtonClicking this button opens a File Open dialog to allow the external graphics file to be selected.

Figure 10-15, Plot Overlay, Use External File

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Receptors 10-29

External File - Details / PreviewRadio ButtonsSetting the radio button to Details allows the information about the drawing dimensions and Flaresim origin to be defined. Setting it to Preview displays the contents of the external file with an overlay showing the Receptor Grid dimensions overlaid on the drawing.

The first two sets of values define the plot dimensions covered by the external file. The names of the axes displayed are updated as appropriate to the setting of the Receptor Grid orientation on the Extent tab.

File Dimension - MinimumRange -10,000m to 10,000mThe minimum value for the plot dimension in the external file.

File Dimension - MaximumRange -10,000m to 10,000mThe maximum value for the plot dimension in the external file.

The two Flaresim Location of Origin fields define where the Flaresim 0, 0 point is located within the drawing file using the drawing files dimensions. Again the names of the coordinates are updated to match the grid orientation setting.

Location of Flaresim OriginRange -10,000m to 10,000mThe coordinates of the Flaresim origin point within the drawing.

Show OverlayCheck boxSet this to include the overlay drawing on the isopleth plots for this Receptor Grid.

Reset ExtentButtonClicking this button resets the external plot file dimensions to match those of the Receptor Grid.

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External Plot File Example

As an example of how these values should be set, consider the following. An external plot plan drawing is available which covers master plot plan coordinates from 1000m to 3000m in the X dimension and from 0m to 2000m in the Y dimension. In the master coordinates the flare stack is located at 2600, 1200.

Assuming our Flaresim model has been run with the stack located at 0, 0 within the model and we have a Receptor Grid defined for the Northing - Easting plane. The settings required to use the plot overlay would be

Northing Min = 0mNorthing Max = 2000mEasting Min = 1000mEasting Max = 3000mFlaresim Origin Northing = 1200mFlaresim Origin Easting = 2600m

Generally the dimensions of the plot plan should exceed those covered by the receptor grid or results can be unpredictable. In our example this would imply following dimensions for the receptor grid.

Northing Minimum = -1200mNorthing Maximum = 800mEasting Minimum = -1600mEasting Maximum = 400m

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Receptors 10-31

Flaresim Overlay File Type

When the File Type is set to Use Flaresim Overlay the options are as shown below.

Overlay NameDrop down list: Available Overlay objectsThis selects which of the Overlay objects defined in this case is to be used as the background drawings for the isopleth plots in this Receptor Grid. No check is made that the Overlay has the correct orientation.

Show OverlayCheck boxSet this to include the overlay drawing on the isopleth plots for this Receptor Grid.

Chapter 13 describes how to create and edit Flaresim Overlay objects.

10.3.9 Grid Graphic Report Tab

The Graphic Report tab of the Receptor Grid view allows the user to display a graphical report of isopleth results or export the data points for an isopleth curve. Printing or saving of graphic reports is handled by the File - Print Graphic Reports menu option.

Figure 10-16, Plot Overlay Tab, Flaresim Overlay

10-31


ButtonThis opens a standard file open dialog to allow selection of the layout file for the graphical report.

Layout File FilenameThis defines the name of the graphic report layout file that will be used to generate graphic reports for this receptor grid. The default value set when the Receptor Point is created is defined in the Files tab of the Preferences view.

Layout files describe the background text, data items and graphics formatting instructions required to define a graphics report in an XML formatted file with the extension .LAY.

Standard layout files are shipped with Flaresim to provide graphic report definitions for 1 and 2 stack systems with 1 or 2 tips on A4 and Letter paper sizes. Appendix A describes the structure and the elements that make up a layout file.

Graphic Report Data - VariableDrop down List: Radiation / Noise / Temperature / Concentration

Figure 10-17, Graphic Report Tab

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Receptors 10-33

Selects the type of isopleth to be viewed on the graphic report - Radiation, Noise, Temperature or Concentration.

For rapid output of all types of Graphic Report use the Print - Graphic Reports menu option.

Graphic Report Data - Contour InterpolationDrop down List: Linear / Cubic / BSplineSelects the method used to generate the isopleth curves from the receptor grid data points.

The Linear option uses the least interpolation and as a result the points generated will be in closest agreement to the data values in the grid. However this may result in more jagged looking isopleth curves if a coarse receptor grid is used i.e. fewer points are calculated. The BSpline method offers the smoothest curves if a coarse grid is used but individual points on the curves may not show such good agreement with the original grid results. The Cubic method offers an alternative smoothing method.

Graphic Report Options - Label Isopleth CurvesCheck boxSet this to generate single letter labels for each of the isopleth curves. This allows individual curves to be more easily distinguished on black and white printed output. It is not normally required for colour output.

Graphic Report Options - Label Isopleth CurvesCheck boxSet this to generate single letter labels for each of the isopleth curves. This allows individual curves to be more easily distinguished on black and white printed output. It is not normally required for colour output.

Export Isopleth PointsButtonClicking this button opens a File Save dialog that allows the calculated isopleth coordinates for the selected isopleth type to be exported. The options for saving are as a XML file, a comma separated CSV file or as an Autocad compatible script file SCR.

10-33


For rapid output of all types of Graphic Report use the Print - Graphic Reports menu option.

View Graphic ReportButtonClicking this button generates and displays on the screen a graphic report from the selected layout file for the selected variable. The graphic report is displayed in its own window and by default is displayed as a maximised view as shown below. The graphic report window can be minimised, resized and closed using standard windows methods.

Figure 10-18, Sample Graphic Report

10-34

Shields 11-1

11-1

Page

11 Shields

11.1 Shield View . . . . . . . . . . . . . . . . . . . . . . . . . .4

11.1.1 Common Fields . . . . . . . . . . . . . . . . . . . . . . 411.1.2 Definition Tab . . . . . . . . . . . . . . . . . . . . . . . . 511.1.3 Definition Tab - User Water Screen Method 511.1.4 Definition Tab - Long Water Screen Method611.1.5 Sections Tab . . . . . . . . . . . . . . . . . . . . . . . . . 8

11.2 Rectangle Builder. . . . . . . . . . . . . . . . . . . . 11

11.3 Polygon Builder . . . . . . . . . . . . . . . . . . . . .13

11.4 Pit / Hut Builder . . . . . . . . . . . . . . . . . . . . .15

11.5 Transform View . . . . . . . . . . . . . . . . . . . . .17

11-2

11-2

Shields 11-3

The Shield object models the use of water sprays or solid shields to reduce the transmission of radiation and noise. Each shield object is composed of one or more polygonal shapes or sections. Multiple sections may be defined to describe complex shield structures such as a burn pit.

The transmission of radiation through a shield can be modelled either by user specified transmissivity factors or for water screens by transmissivity factors calculated from details of the screen thickness and the flame temperature. A method is also provided to calculate the effective thickness of a water screen given details of the water flow rate and other details of the water spray. The transmission of noise through a shield is defined by a user specified transmission factor.

Shield objects may be created using the Add-Shield drop down menu option or by selecting the Shield branch in the Case Navigator view and clicking the Add button.

An existing Shield object may be viewed by double clicking it in the Case Navigator view or by selecting it in the Case Navigator view and clicking the View button.

All defined Shield objects will be included in the calculations unless they have been set to Ignored. A Shield may be set to ignored by selecting it in the Case Navigator view and clicking the Ignore button. An Ignored Shield object can be restored to the calculations by selecting it in the Case Navigator view and clicking the Activate button. Alternatively a Shield object can be ignored and restored by setting or clearing the check box on its view.

A Shield object can be deleted either by clicking the Delete button on its view or by selecting it in the Case Navigator view and clicking the Delete button on this view.

11-3

11-4 Shield View

11.1 Shield View

The following figure shows the tip view as it would appear for a newly created Shield object.


NameTextEnter text to identify this Shield object.

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this shield object is complete and ready for calculation.

Figure 11-1, Shield Details View

11-4

Shields 11-5

IgnoredCheck box Clear to include this shield in the calculations or set to ignore this shield when calculating.

11.1.2 Definition Tab

The Definition tab of the Shield view, Figure 11-1, has the following fields.

Details Radiation - Screen TypeDrop down List - User / Water ScreenThis drop down list selects the type of shield. The User option is used for solid shields or water screens when it is desired to specify the transmissivity of the screen directly. The Water Screen option is used when it is desired the calculate the transmissivity for a known thickness of a water screen.

When this field is set to User the view changes to display the Transmissivity field to allow the transmissivity to be defined. When the field is set to Water Screen the view changes to that shown in Figure 11-2 below.

Details Radiation - TransmissivityRange 0 to 1This defines the fraction of radiation transmitted by the shield. This field is only displayed when the Type field is set to User.

Details Noise - TransmissivityRange 0 to 1This defines the fraction of noise transmitted by the shield. The factor is applied to the noise power.

11.1.3 Definition Tab - User Water Screen Method

When the Type field on the Details tab is set to Water Screen the view changes to that shown below in Figure 11-2.

11-5

11-6 Shield View

Layer Thickness MethodDrop down list: User / LongThis drop down list specifies the method that will be used to determine the thickness of the water screen. If the User method is selected the Layer Thickness field is displayed to allow the thickness to be specified. If the Long method is selected the fields described in section 11.1.4 will be displayed to allow details of the water screen to be provided to allow the water screen thickness to be calculated.

Layer ThicknessRange 0.001 to 1000 mmThis field defines the thickness of the water screen. The thickness will be used to calculate the transmissivity of the water screen as a function of the thickness and the flame temperature of the flare.

This field is only displayed when the Layer Thickness Calculation option is set to User.

11.1.4 Definition Tab - Long Water Screen Method

When the Shield type is set to Water Screen and the Layer Thickness Calculation is set to Long then the following fields will be displayed.

Figure 11-2, Details Tab, User Water Screen Method

11-6

Shields 11-7

Water FlowRange 0 to 1000 m3/sThis field defines the water flow rate for the calculation of the water screen layer thickness using the Long method.

Nozzle DiameterRange 0 to 1000 mmThis field defines the nozzle diameter for the calculation of the water screen layer thickness using the Long method.

Number of NozzlesRange 1 to 100The number of water spray nozzles used.

Droplet VelocityRange 1 to 20 m/sThis field defines the droplet velocity to be used in the calculation of the water screen layer thickness using the Long method.

Calc. Layer ThicknessCalculated resultThis field displays the thickness of the water screen layer calculated using the Long method.

Figure 11-3, Details Tab, Long Water Screen Method

11-7

11-8 Shield View

11.1.5 Sections Tab

The sections tab of the Shield view is shown below. This view lists the individual sections or panels that make up the complete shield. Each section is defined as a polygon with 3 or more points or vertices to define its extremities. The shield sections may be updated by selecting the line describing the section and then updating values in the Section Details region below and / or clicking one of the action buttons.

Section ListList box: All defined shield sectionsThe Section List displays all of the shield sections defined for this shield. Selecting a section in the list updates the Section Details region with the corresponding information.

Figure 11-4, Sections Tab

11-8

Shields 11-9

Section List - Add SectionButtonCreates a new shield section. The new section will be selected automatically in the Section List box.

Section List - Delete SectionButtonDeletes the selected shield section.

Section List - Make Pit / HutButtonOpens the Pit / Hut Builder view ready to define a new shield. See 11.2.

Section List - Transform ShieldButtonOpens the Transform view to rotate or move the shield. See 11.3.

Section Details - Section NameTextThis field allows the shield section to be given a descriptive name.

Section Details - Add VertexButtonThis button adds a new vertex to the bottom of the list of vertices for the current shield section.

Section Details - Delete VertexButtonThis button deletes the selected vertex from the list.

Section Details - Sort VerticesButtonThis button sorts the list of vertices for the shield section.

When using the shield section editor it is important that the list of vertices that define the section are entered in a way that each vertex is directly connected to the preceding vertex in the list in a continuous clockwise or anti-clockwise direction.

11-9

11-10 Shield View

For example if entering the vertices to define a rectangular shield section, the four vertices, A, B, C and D must be entered as shown below.

If vertices are not entered in the correct order their correct extent cannot be calculated and the radiation and noise reduction results will be misleading and inaccurate. This can usually be seen as very irregular isopleths in the Receptor Grid view.

The Sort Vertices button will sort a list of vertices into the correct order in most cases.

Section Details - Make RectangleButtonClicking this button opens the Rectangle Builder view, see section 11.2. This allows rapid definition of a rectangular shield section.

Section Details - Make PolygonButtonClicking this button opens the Polygon Builder view, see section 11.3. This allows rapid definition of a polygonal shield section.

Vertex List - NorthingRange -10,000 to 10,000 mThe northing coordinate of the vertex.

Vertex List - EastingRange -10,000 to 10,000 mThe easting coordinate of the vertex.

Vertex List - ElevationRange -10,000 to 10,000 mThe elevation coordinate of the vertex.

Correct IncorrectCorrect

11-10

Shields 11-11

11.2 Rectangle Builder

The Rectangle Builder view is shown below. Its purpose is to allow rapid creation of rectangular shield sections.This view is modal and must be completed and closed before other Flaresim views can be used.

Rectangle - HeightRange 0 to 1000mThe height of the shield section.

Rectangle - WidthRange 0 to 1000mThe width of the shield section.

Centre Point Location - NorthingRange -10,000 to 10,000mThe northing coordinate of the centre of the rectangle.

Centre Point Location - EastingRange -10,000 to 10,000mThe easting coordinate of the centre of the rectangle.

Figure 11-5, Rectangle Builder

11-11

11-12 Rectangle Builder

Centre Point Location - ElevationRange -10,000 to 10,000mThe elevation coordinate of the centre of the rectangle.

Orientation - Angle to NorthRange 0 to 360 degreesThe angle from North of the rectangle.

Orientation - Angle to HorizontalRange -90 to 90 degreesThe angle from horizontal of the rectangle. The default value of 90 degrees implies a vertical rectangle.

OKButtonCloses the Rectangle Builder view, accepting the input data. Note any existing section vertices will be replaced by the new rectangular section.

CancelButtonCloses the Rectangle Builder view, discarding the input data.

11-12

Shields 11-13

11.3 Polygon Builder

The Polygon Builder view is shown below. Its purpose is to allow rapid creation of polygonal shield sections. The most common use of this view will be to create polygonal sections of 12 or more vertices to approximate circular water sprays. This view is modal and must be completed and closed before other Flaresim views can be used.

Number of VerticesRange 3 to 100The number of vertices that will define the extents of the shield section. The default number of 12 will approximate a circular spray shield to a reasonable accuracy though a greater number can be used if required.

RadiusRange 0.1 to 1,000mThe radius of the polygonal shield section i.e. the distance from the centre of the polygon to each vertex.

Figure 11-6, Polygon Builder

11-13

11-14 Polygon Builder

Rectangle Centre - NorthingRange -10,000 to 10,000mThe northing coordinate of the centre of the polygon.

Rectangle Centre - EastingRange -10,000 to 10,000mThe easting coordinate of the centre of the polygon.

Rectangle Centre - ElevationRange -10,000 to 10,000mThe elevation coordinate of the centre of the polygon.

Orientation - Angle to NorthRange 0 to 360 degreesThe angle from North of the polygon.

Orientation - Angle to HorizontalRange -90 to 90 degreesThe angle from horizontal of the polygon. The default value of 90 degrees implies a vertical polygon.

OKButtonCloses the Polygon Builder view, accepting the input data. Note any existing section vertices will be replaced by the new polygon data.

CancelButtonCloses the Polygon Builder view, discarding the input data.

11-14

Shields 11-15

11.4 Pit / Hut Builder

The Pit / Hut Builder view is shown below. The function of this view is to create the multiple shield sections that make up a burn pit or alternatively a protective hut. It will automatically create 4 rectangular wall sections and a rectangular base or roof section. This view is modal and must be closed before other Flaresim views can be used.

DetailsRadio button: Pit / HutSelects whether the view will define data for a pit or a hut.

In both cases 4 vertical rectangular walls and a horizontal rectangular section will be created from the data supplied. In the case of a Pit the horizontal section will form the base of the burn pit while for a Hut the horizontal section will form the roof.

Length (Northing Dimension)Range 0.1 to 1,000mThe length of the burn pit/hut. The length is assumed to be the dimension in the north-south direction.

Figure 11-7, Pit / Hut Builder

11-15

11-16 Pit / Hut Builder

Width (Easting Dimension)Range 0.1 to 1,000mThe width of the burn pit/hut.The width is assumed to be the dimension in the east-west direction.

Depth / HeightRange 0.1 to 1,000mThe depth of the burn pit or the height of the hut.

Rectangle Centre - NorthingRange -10,000 to 10,000mThe northing coordinate of the centre of the burn pit or hut base.

Rectangle Centre - EastingRange -10,000 to 10,000mThe easting coordinate of the centre of the burn pit or hut base.

Rectangle Centre - ElevationRange -10,000 to 10,000mThe elevation coordinate of the centre of the burn pit or hut base.

OKButtonCloses the Pit/Hut Builder view, accepting the input data. Note any existing shield section data will be replaced by the new pit/hut data.

CancelButtonCloses the Pit Builder view, discarding the input data.

11-16

Shields 11-17

11.5 Transform View

The Transform view is shown below. The purpose of this view is to relocate or rotate an existing shield section. It is used by entering the data required to define the move or rotation and then clicking the Apply button

Move Section - NorthRange -10,000 to 10,000 mThis defines the distance the shield sections are to be moved in the north-south direction.

Move Section - EastRange -10,000 to 10,000 mThis defines the distance the shield sections are to be moved in the east-west direction.

Move Section - ElevationRange -10,000 to 10,000 mThis defines the distance the shield sections are to be moved up or down.

Figure 11-8, Transform View

11-17

11-18 Transform View

Rotate Section - Angle to NorthRange -360 to 360 degreesThis defines the amount the shield sections are to be rotated from North i.e. around a vertical axis.

Rotate Section - Angle to HorizontalRange -360 to 360 degreesThis defines the amount the shield sections are to be rotated from the vertical i.e. around a horizontal axis.

Rotation Centre Point - NorthingRange -10,000 to 10,000 mThis defines the north coordinate for the centre of rotation to be used when rotating the shield sections.

Rotation Centre EastRange -10,000 to 10,000 mThis defines the east coordinate for the centre of rotation to be used when rotating the shield sections.

Rotation - Centre ElevationRange -10,000 to 10,000 mThis defines the elevation coordinate for the centre of rotation to be used when rotating the shield sections.

Apply Transform To All SectionsCheck boxIf this check box is set then the transform will be applied to all of the sections of the shield. If not it will only be applied to the section that was selected when the Transform button was clicked.

OKButtonThis closes the Transform view and applies the specified movement or rotation to the shield section.

CancelButtonClose the Transform view, discarding any defined transformation data.

11-18

Shields 11-19

In applying a transform for simultaneous movement and rotation the order in which these are applied is firstly movement, secondly rotation from North around the vertical axis and finally rotation from horizontal around the horizontal axis.

The effect of a given transform is not always obvious and it is suggested that more complex movements be done in single steps to avoid possible confusion.

11-19

11-20 Transform View

11-20

Dispersion 12-1

12-1

Page

12 Dispersion

12.1 Dispersion View . . . . . . . . . . . . . . . . . . . . . .4

12.1.1 Common Fields . . . . . . . . . . . . . . . . . . . . . . 412.1.2 Input Data Tab. . . . . . . . . . . . . . . . . . . . . . . . 512.1.3 Pollutants Tab. . . . . . . . . . . . . . . . . . . . . . . . 812.1.4 Results Tab . . . . . . . . . . . . . . . . . . . . . . . . . . 912.1.5 Plot Overlay Tab . . . . . . . . . . . . . . . . . . . . . .1112.1.6 Graphic Report Tab . . . . . . . . . . . . . . . . . . .11

12.2 Implementation Details . . . . . . . . . . . . . . .12

12-2

12-2

Dispersion 12-3

The Dispersion object provides a Gaussian dispersion calculation to model the dispersion of combustion gases from burning flares and dispersion of relieved fluid in the event of a flame out condition. Gaussian dispersion is a simple model of gas dispersion appropriate for a first pass screening of emissions from a flare system. In its current implementation in Flaresim it is suitable for buoyant fluids only and does not include modelling of terrain or structure effects, both of which can have a significant impact on dispersion results.

The Dispersion object allows generation of contour isopleth results for a single pollutant or a simple downwind plot for multiple pollutants. The source of pollutants is either the calculated combustion gas or the components in the relieved fluid. Multiple Dispersion objects can be defined to carry out different calculations.

Dispersion objects may be created selecting the Add-Dispersion drop down menu option or by selecting the Dispersion branch in the Case Navigator and clicking the Add button.

An existing Dispersion object may be viewed by double clicking it in the Case Navigator or by selecting it in the Case Navigator and clicking the View button.

Dispersion objects will be included in the calculations providing that the appropriate option has been selected in the Calculation Options view unless they have been set to Ignored. A Dispersion may be set to ignored by selecting it in the Case Navigator and clicking the Ignore button. An Ignored Dispersion object can be restored to the calculations by selecting it in the Case Navigator and clicking the Activate button. Alternatively a Dispersion object can be ignored and restored by setting or clearing the Ignored check box on its view.

A Dispersion object can be deleted either by clicking the Delete button on its view or by selecting it in the Case Navigator and clicking the Case Navigator Delete button.

12-3

12-4 Dispersion View

12.1 Dispersion View

The following figure shows the Dispersion view for entering and updating Dispersion data.


NameTextEnter a name to identify this Dispersion object. The entry will be automatically processed to remove any characters that are not allowed in file names.

Status TextStatus messageThe message displayed in this field and its colour indicates whether the data for this Dispersion object is complete and ready for calculation.

Figure 12-1, Dispersion View

12-4

Dispersion 12-5

IgnoredCheck boxClear to include this Dispersion in the calculations or set to ignore this Dispersion when calculating. The effect of setting this check box will be to exclude the Dispersion object from the calculations.

Dispersion objects will only be considered for calculation if the appropriate option is set in the General tab of the Calculations Options view.

12.1.2 Input Data Tab

The Input Data tab of a newly created Dispersion object is as shown in Figure 12-1 above. The following fields determine the type of Dispersion calculation that will be performed.

Pollutant SourceRadio buttons: Combustion Gas / Flared FluidIf the combustion gas option is selected the list of pollutant components will be loaded from the combustion gas compositions calculated for the flare tips in the model. If the Flared Fluid option is selected the list of pollutant components will be loaded from the component lists of the fluids in the model.

If the flared fluids are defined by bulk properties then no dispersion modelling can be performed for the flared fluid. Combustion gas modelling can still be done in this case since the combustion gas composition can be calculated using an assumed composition.

Calculation TypeRadio buttons: Contour Plot / Downwind Line PlotThe dispersion calculations can be performed to generate either a composition isopleth contour plot for a single pollutant or a plot of muliple pollutant compositions along a single line downwind of a selected origin.

12-5


Contour Plot Data Entry

The data entry items for a contour plot dispersion calculation are shown below.

Contour Plot Extent - Contours HeightRange: 0m to 1,000 mThe height of the contours plane. All contours are generated for a horizontal plane i.e. a Northing-Easting orientation.

Northing - MinimumRange: -50,000 to 50,000 mThe minimum extent of the contour plot in the northing direction.

Northing - MaximumRange: -50,000 to 50,000 mThe maximum extent of the contour plot in the northing direction.

Northing - Number of PointsRange: 1 to 1001The number of increments that the distance between the minimum and maximum extents will be divided into.

Figure 12-2, Contour Plot Data Entry

12-6

Dispersion 12-7

Easting - MinimumRange: -50,000 to 50,000 mThe minimum extent of the contour plot in the easting direction.

Easting - MaximumRange: -50,000 to 50,000 mThe maximum extent of the contour plot in the easting direction.

Easting - Number of PointsRange: 1 to 1001The number of increments that the distance between the minimum and maximum extents will be divided into.

Downwind Line Plot Data Entry

The data entry items for a contour plot dispersion calculation are shown below.

Line Plot Details - Line Through PointDrop down list: Origin and defined tip exit locationsThis entry defines the point on which the downwind line calculation is based. The downwind distances specified are calculated from this selected point.

Figure 12-3, Downwind Line Plot Data Entry

12-7


Line Plot Details - Height For CalculationRange: 0m to 1,000 mThe height at which the pollutant concentrations are to be calculated.

Downwind Distance - MinimumRange: 0 to 50,000 mThe minimum downwind distance for the line plot.

Downwind Distance - MaximumRange: 0 to 50,000 mThe maximum downwind distance for the line plot.

Downwind Distance - Number of PointsRange: 1 to 1001The number of increments that the distance between the minimum and maximum extents will be divided into.

12.1.3 Pollutants Tab

Figure 12-4, Pollutants Tab

12-8

Dispersion 12-9

The Pollutants tab view shows a list of the pollutant components found in the selected Pollutant source.

If this is set to combustion gases all of the combustion results for each active tip are scanned to complete the list of pollutants though the O2 and N2 components are not added to the list. If the source is set to Flared Fluid all of the active fluid compositions in the case are scanned. If all of the active fluids are defined by bulk properties then the pollutant list will be empty.

PlotCheck boxSet the check box for the pollutants that should be included in the dispersion calculations. For a contour calculation only one component may be selected. Multiple components can be selected for a downwind line plot.

12.1.4 Results Tab

Figure 12-5, Results Tab, Downwind Line Results

12-9


The view above shows the results obtained for a downwind line plot dispersion calculations. The view below shows the results for a contour calculation. In both cases the Display and Export options available are the same.

DisplayDrop down list: Table / PlotSelects whether the dispersion results are displayed as a table or as a graph.

When a new Dispersion object is created the graph display settings are set to the defaults defined in the Preferences View, see section 5.4.

ExportButtonAllows the calculated thermal radiation results to be exported to a file. If the data is displayed as a table it may be exported to an Excel XLS file or a comma separated CSV file. If displayed as a graph it

Figure 12-6, Results Tab, Contour Results

12-10

Dispersion 12-11

may be exported to a JPG, PNG, BMP, WMF or EMF graphics file. In either case a standard file dialog box will appear to allow the name and file type to be entered.

The contour plot view may be customised using the Zoom and Customise options as described in Chapter 13.

12.1.5 Plot Overlay Tab

The options in the Plot Overlay tab of the Dispersion object apply to the contour plot calculation type only. Their operation is identical to that described for the Plot Overlay tab of the Receptor Grid object, see section 10.3.8.

12.1.6 Graphic Report Tab

The options in the Graphic Report tab of the Dispersion object apply to the contour plot calculation type only. Their operation is identical to that described for the Graphic Report tab of the Receptor Grid object, see section 10.3.9.

Graphic Reports are not available for the downwind line plot dispersion option.

12-11

12-12 Implementation Details

12.2 Implementation Details

The Flaresim Gaussian dispersion calculations make the following key assumptions in their implementation.

A. The gas is assumed to be buoyant.

In the case of the combustion gases this is a reasonable assumption at normal flame temperatures. In the case of the uncombusted flared fluid, a check is made to confirm that the temperature/mole weight of the fluid leads to a gas density that is lighter than air at 120C as a precondition for running the calculations.

B. The combustion gas source is assumed to be the end of the flame.

The Flame Shape tab of the Tip view can be used to see the location of the end of the flame.

C. Multiple sources are summed to provide a final result

If multiple sources are specified in a model i.e. there are multiple tips then the dispersion results are calculated for each individual tip and then summed to give the final result.

D. Minimum Distance is 100m

The dispersions coefficients used are calculated from correlations that were validated for a minimum distance of 100m downwind of the source. While Flaresim may calculate Gaussian dispersion results at closer distances they should be regarded as extrapolations and of low reliability.

12-12

Overlays And Isopleths 13-1

13 Overlays And Isopleths

Page13.1 Overlay View. . . . . . . . . . . . . . . . . . . . . . . . .4

13.1.1 Common Fields . . . . . . . . . . . . . . . . . . . . . . 413.1.2 Details Tab . . . . . . . . . . . . . . . . . . . . . . . . . . 413.1.3 Editor Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . 513.1.4 Overlay Editor Tool bar . . . . . . . . . . . . . . . . 713.1.5 Overlay Editor - Object Properties . . . . . . 1013.1.6 Overlay Editor - Edit Mode . . . . . . . . . . . . 13

13.2 Zoom View . . . . . . . . . . . . . . . . . . . . . . . . .15

13.3 Isopleth Customise View. . . . . . . . . . . . . .17

13.3.1 Plot Details Tab. . . . . . . . . . . . . . . . . . . . . . 1813.3.2 Contour Details Tab . . . . . . . . . . . . . . . . . . 2113.3.3 Text Details Tab . . . . . . . . . . . . . . . . . . . . . 22

13-1


Page

13-2


Overlays are drawings such as plot plans created in Flaresim to add as background pictures to isopleth plots to show graphically the extent of the isopleths. The overlay editor provided allows creation of simple drawings but is not a a substitute for a full graphics program. Externally created files can also be used as background pictures - see the Plot Overlay tab of Receptor Grid and Dispersion views.

Overlay objects may be created using the Add-Overlay drop down menu option or by selecting the Overlay branch in the Case Navigator view and clicking the Add button.

An existing Overlay object may be viewed by double clicking it in the Case Navigator view or by selecting it in the Case Navigator view and clicking the View button.

Overlay objects can be used by one or more Receptor Grid or Dispersion objects (client objects). Overlays are selected and their display is controlled through the Plot Overlay tab of the client object view.

Overlay objects can be deleted by selecting them in the Case Navigator and clicking the Delete button or by using the Delete button on their view.

Isopleth Zoom and Isopleth Customisation views are accessible from all isopleth display tabs. These include the Radiation, Noise, Temperature and Concentration tabs of the Receptor Grid views and the Results tab of the Dispersion object view when used for dispersion contour calculations. The Zoom and Customisation views allow the appearance of individual isopleths to be manipulated.

Isopleth Zoom and Isopleth Customisation views pop up alongside a particular isopleth display and will close automatically when that display is closed.

13-3

13-4 Overlay View

13.1 Overlay View

The following figure show the Overlay view for creating and modifying overlay pictures.


NameTextEnter text to identify this Receptor Point object.

13.1.2 Details Tab

The Details tab of the Overlay view, see Figure 13-1, has the following data entry fields.

Figure 13-1, Overlay View

13-4


Overlay Type -Overlay PlaneDrop down list: Northing-Easting / Elevation-Northing / Elevation-EastingDefines the plane of the Overlay drawing. Selection of the plane automatically updates the labels for the remaining entries in the this tab.

File Dimension - MinimumRange: -50,000 to 50,000 mThe minimum extent of the overlay drawing in the labelled direction.

File Dimension - MaximumRange: -50,000 to 50,000 mThe maximum extent of the overlay drawing in the labelled direction.

Update Details From Grid / Dispersion - SelectDrop down list: All Grids and Dispersions in CaseThis drop down provides a list of all of the Receptor Grid and Dispersion objects in the case so that it can be used as the basis for setting the Overlay dimensions.

Update Details From Grid / Dispersion - UpdateButtonClicking this copies the orientation and each axis minimum and maximum dimensions from the selected Receptor Grid or Dispersion object. This is a one-off copy and no link is made between the Overlay and the selected source object.

13.1.3 Editor Tab

The Overlay Editor tab allows the creation and modification of background graphics from scratch. The view shown below has three main sections, the tool bar, the information and setting region and the drawing display.

13-5

13-6 Overlay View

Current Location - X LocCursor location in selected unitsThis updates as the mouse is moved around the drawing to show the X location of the cursor.

Current Location - Y LocCursor location in selected unitsThis updates as the mouse is moved around the drawing to show the Y location of the cursor.

Show StacksCheck boxIf this check box is set the stacks will be added to the displayed overlay drawing to act as guides for other drawing actions. Clearing the check box clears the stack and tip elements. The stack drawing elements will not form part of the saved Overlay. The setting is not saved.

Figure 13-2, Editor Tab

13-6


The stack elements shown are the projection of the stack onto the Overlay plane i.e. vertical stacks will appear as a point on an Overlay with a Northing-Easting orientation.

RefreshButtonClicking this button updates any open Receptor Grid or Dispersion isopleth plot views that are using the current Overlay so that they display the latest version of the Overlay. Newly opened isopleth views and report graphics always display the latest Overlay version.

13.1.4 Overlay Editor Tool bar

The icons on this tool bar may be clicked to perform the following actions or select a drawing mode. A blue box is shown around the current active icon.

Opens a file to import into the current Overlay. A standard windows File Open Dialog will be displayed to allow the file to be selected. Allowed types of input file are JPG, PNG, BMP, WMF or EMF standard Windows file types, Flaresim version 2 overlays FSG and Flaresim version 3 overlays FSO.

The imported file will replace the current drawing. If you want to add an external file to an existing Overlay use the Add Picture option .

Exports the current Overlay picture. A standard windows File Save Dialog will be displayed to allow the export file to be selected. The file may be saved as a JPG, PNG, BMP, WMF or EMF file.

Figure 13-3, Overlay Editor Tool bar

13-7

13-8 Overlay View

Puts the drawing in selection and edit mode. When this icon is selected, clicking objects in the drawing selects them for editing, as described in section below.

Puts the drawing in Add Line mode.selection When this icon is selected, clicking and dragging in the drawing will create a new line.

Puts the drawing in Add Rectangle mode. When this icon is selected, clicking and dragging in the drawing will create a new rectangle.

Puts the drawing in Add Rounded Rectangle mode. When this icon is selected, clicking and dragging in the drawing will create a new rounded rectangle.

Puts the drawing in Add Ellipse mode. When this icon is selected, clicking and dragging in the drawing will create a new ellipse or circle.

Puts the drawing in Add Polyline mode. When this icon is selected, the first click will start a multiple segment line and each subsequent click adds a new segment. Double clicking or the Esc key indicate completion of the Polyline.

Puts the drawing in Add Polygon mode. When this icon is selected, the first click will start a drawing a polygon and each subsequent click adds a new side to the polygon. Double clicking or the Esc key indicate completion and closure of the Polygon.

Puts the drawing in Add Text mode. Click the left mouse button at the point where the text is to start - a vertical blinking line will be displayed. Type the text and finish by hitting the enter key.

13-8


Puts the drawing in Add Picture mode. Using the Add Picture mode is a two step process.

First as soon as the icon is clicked a File Open dialog will appear to allow selection of the picture to be added. A JPG, PNG, BMP, WMF or EMF file can be selected.

After file selection, clicking and dragging in the drawing will define a box within which the picture from the file will be drawn. A single picture can be added to the drawing multiple times. To change the picture being added, click the icon again.

Displays a drop down list to allow selection of the properties for new objects or to change the style of an existing object. The options in the list are shown below and their usage is covered below.

Displays a drop down list to allow the rearrangement of the relative positioning, orientation or grouping of the selected

Figure 13-4, Object Properties Drop Down

13-9

13-10 Overlay View

object in Edit Mode. The options in the list are shown below and their usage is covered below.

Zooms in on the overlay drawing i.e. displays the drawing at a larger scale. Scroll bars will appear if required and can be used to scroll around the drawing.

Zooms out on the overlay drawing i.e. displays the drawing at a smaller scale.

Displays the currently selected zoom size of the drawing as a percentage of the full size. Drop down button can be used to select pre-defined zoom percentages.

13.1.5 Overlay Editor - Object Properties

The Overlay Editor is object based and the colour and drawing style of each object are set using the drop down list. This drop down sets the object properties for new objects added in Draw Mode or changes the properties of objects selected in Edit Mode.

The properties in the drop down list that can be set are.

Line ColourThis displays a standard windows Colour Selection Dialog as shown below. Click the colour required and then the Ok button. The

Figure 13-5, Object Arrange Drop Down

13-10


selected colour applies to individual line objects, polyline objects and the outside lines for rectangle, rounded rectangle, ellipse and polygon objects.

Line StyleThis displays the following dialog to allow the line width and line style to be selected. Enter the line width required and select the line style from the drop down list then click Ok. The selected style applies to individual line objects, polyline objects and the outside lines for rectangle, rounded rectangle, ellipse and polygon objects.

Fill ColourThis displays the standard windows Colour Selection Dialog as shown above. The selected colour applies to the interior of rectangle, rounded rectangle, ellipse and polygon objects.

Figure 13-6, Colour Selection Dialog

Figure 13-7, Line Style Selection

13-11

13-12 Overlay View

Fill StyleThis displays the following dialog. Select the Fill style from the drop down list and click Ok. The selected fill style applies to the interior of rectangle, rounded rectangle, ellipse and polygon objects.

Background Colour This displays the standard windows Colour Selection Dialog as shown above. The selected colour applies background colour of the plot.

Text ColourThis displays the standard windows Colour Selection Dialog as shown above. The selected colour applies to the text objects.

Text FontThis displays a standard windows Font Properties Dialog as shown below. Select the font name, size and style and click Ok. Note that the font size selected has to be scaled for use on the overlay and so a given point size may not display with the exact height requested.

Figure 13-8, Fill Style Selection

13-12


13.1.6 Overlay Editor - Edit Mode

In Edit mode it is possible to modify existing objects in the plot overlay. Edit mode is selected by clicking the button in the tool bar. Once the editor is in edit mode the cursor will change to show a simple arrow.

Edit mode can be used to move, resize, change the properties or change the arrangement of the objects that make up a plot overlay.

Selecting ObjectsA single object can be selected by clicking on it with the left mouse button. Once selected the object will display white boxes at the corners and sides of its bounding rectangle as shown below.

Figure 13-9, Font Properties Dialog

Figure 13-10, Selected Object

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13-14 Overlay View

Multiple objects can be selecting by clicking and holding the left mouse button to draw a rectangle around multiple objects. In this case grey boxes are displayed at the corners and sides of the rectangles bounding each selected object. Alternatively hold down the Shift key and click to select multiple objects.

Resizing ObjectsA selected object can be resized by moving the cursor over one of the white boxes in the bounding rectangle. When the cursor changes to a two headed arrow, click and hold the left mouse button then drag to resize the object.

Moving ObjectsAn object can be moved by clicking and holding the left mouse button on the object and dragging the object to the new position. The cursor will show a four arrowed icon. To move multiple objects first select them then click and drag one of the them.

Changing Object PropertiesThe properties of an object can be changed by selecting it then using the drop down to select the property to be changed.

Rotating and Flipping ObjectsObjects can be rotated or flipped by selecting it then using the drop down to select the angle of rotation or horizontal or vertical flip.

Changing Object Stacking OrderThe stacking order of objects, i.e. whether one object is displayed in front or behind another object, is set by selecting it then using the

drop down to bring the object forward or in front of other objects or send it backwards or behind other objects.

Grouping or Ungrouping ObjectsMultiple objects may be grouped together by selecting them and then using the group option from the drop down. The group of objects can then be treated as a single object for other transformations. A grouped object can be broken into individual objects again by selecting it and using the ungroup from the same drop down menu.

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13.2 Zoom View

The Zoom view shown below will appear on clicking the Zoom button on a Receptor Grid isopleth or a Dispersion object contour plot. The view will appear beside the parent object view and will remain open until closed or until a different tab is selected in the parent object. More than one Zoom view can be open at a time.

The zoom view allows the isopleth to be rescaled to zoom in on a particular section of the isopleth and view its contents in more detail. This is done without recalculating the results, all isopleths drawn will be calculated by interpolation from the original results.

There are two ways of establishing the new scale for the isopleth plot axes.

Firstly, when the Zoom view is open, moving the cursor over isopleth shows a cursor. When this is displayed you can click and drag in the isopleth to select the new zoom region. The updated scale values will be displayed in the Zoom view.

Alternatively the Zoom extents can be set through the zoom view.

Zoom Extents - MinRange: Constrained by isopleth extentsEnter the minimum scale value for the axis.

Figure 13-11, Zoom View

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13-16 Zoom View

Zoom Extents - MaxRange: Constrained by isopleth extentsEnter the minimum scale value for the axis.

Note the labels for the Min and Max entries will be updated according to the orientation of the parent object isopleth.

ApplyButtonClicking this button redraws the isopleths with the current zoom extents.

ResetButtonClicking this button sets the zoom extents back to the original Receptor Grid or Dispersion extents and redraws the isopleths.

Update Extents From ZoomButtonClicking this button copies the current zoom extents to the input extents of the parent Receptor Grid or Dispersion object. Since this effectively changes the input data for the grid the current results will be cleared. The case must be recalculated before any new isopleth results can be viewed.

Update All Isopleths in this GridButtonClicking this button copies the zoom extents for the current isopleth to the other isopleths of the same Receptor Grid. For example updated zoom extents on the Radiation isopleth can be copied to the Noise, Temperature and Concentration isopleths.

It should be emphasised again that the number and range of points calculated are specified on the Extent tab of a Receptor Grid or the Input Data tab of a Dispersion object. Expanding the scale of the plots using the zoom feature does not add any detail to the calculations. To do this you must update the Grid or Dispersion extents and recalculate.

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13.3 Isopleth Customise View

The Isopleth Customise view shown below will appear on clicking the Customise button on a Receptor Grid isopleth or a Dispersion object contour plot. The view will appear beside the parent object view and will remain open until closed or until a different tab is selected in the parent object. More than one Isopleth Customise view can be open at a time.

There is one button on this view.

Update All Isopleths of This TypeButtonClicking this button copies the settings for this isopleth to all other isopleths of the same type in the case. For example if you click the button when updating a Radiation isopleth, the Radiation isopleths of all other Receptor Grids in the case will be updated.

The detailed customisation settings are split across three tabs.

Figure 13-12, Isopleth Customise View

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13-18 Isopleth Customise View

13.3.1 Plot Details Tab

The Plot Details tab of the Isopleth Customisation view is shown as Figure 13-12.

Plot Details - Display GridCheck boxWhen selected plots will show a background grid.

Plot Details - Display FlameCheck boxWhen selected isopleth plots will show a line representing the shape of the flames from any active flare tips.

Plot Details - Display StackCheck boxWhen selected isopleth plots will show lines representing the size and orientation of active flare stacks.

Plot Details - Display TipCheck boxWhen selected isopleth plots will show lines representing the size and orientation of active flare tips.

Plot Details - Display ShieldCheck boxWhen selected isopleth plots will show lines representing the intersection of active shield sections with the plane of the isopleth.

Note that it is the intersection that is displayed not the projection of the shield on the isopleth. If plan view isopleth is at ground level i.e. 0m then the shields will require at least one point with an elevation dimension < 0m in order to intersect with the isopleth plane.

Plot Parameter - Number of linesInteger value 1 to 9This value determines the number of grid lines that will be displayed for each axis of the isopleth plots.

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Plot Parameter - Flame ThicknessInteger value 1 to 50This values defines the width in pixels of the line that will be drawn to represent the flame shape.

Plot Parameter - Stack ThicknessInteger value 1 to 50This values defines the width in pixels of the line that will be drawn to represent each active stack on the isopleth plots.

Plot Parameter - Tip ThicknessInteger value 1 to 50This values defines the width in pixels of the line that will be drawn to represent the each active tip on the isopleth plots.

Plot Parameter - Shield ThicknessInteger value 1 to 50This values defines the width in pixels of the line that will be drawn to represent the shield sections on the isopleth plots.

Plot Colour - Grid ColourColour DialogThis shows the colour that will be used for the background of the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

Figure 13-13, Colour Dialog

13-19


Colours are selected in the dialog by clicking on the colour required and then clicking the Ok button. To close the dialog without changing the colour click the Cancel button.

Plot Details - Flame ColourColour DialogThis shows the colour that will be used to draw the line representing the flame shape on the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

Plot Details - Stack ColourColour DialogThis shows the colour that will be used to draw the line representing the flare stacks on the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

Plot Details - Tip ColourColour DialogThis shows the colour that will be used to draw the line representing the flame shape on the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

Plot Details - ColourColour DialogThis shows the colour that will be used to draw the line representing the shield sections on the isopleth plots. The colour may be selected by double-clicking the sample panel to display the Flaresim colour dialog.

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13.3.2 Contour Details Tab

On the Contour Details tab, see below, it is possible to select the following options for the 10 contour lines that are available for each isopleth.

Contour Details - ValueData InputThis column defines the value for the selected isopleth contour in the units defined at the head of the column.

Contour Details - DisplayCheck boxThis column specifies whether the selected isopleth contour will be displayed. Set the check box to display the contour, clear it to hide the contour. Contours

Contour Details - ColourColour DialogThis column defines the colour to be used for the selected isopleth contour. Double click the sample panel to open the Flaresim colour dialog to change the colour.

Figure 13-14, Contour Details

13-21


Contour Details - WidthData InputThis column defines the line width used to draw the selected isopleth contour.

Contour Details - ValueDrop Down List: Solid / Dash / Dot / DashDot / DashDotDotThis column selects the line style used to draw the selected isopleth contour.

13.3.3 Text Details Tab

The Text Details tab, see below, allows the following settings to be defined.

Text Options - Select Text ItemSelect RowThe rows of this table describe the different text elements that can appear on an isopleth plot. The display properties of each different text element can be set by selecting the row and then using the fields below to modify the properties.

Figure 13-15, Isopleth Text Details

13-22


Not all of the defined properties may be supported for all of the text elements. Where a property cannot be set it will be greyed out while that text element is selected.

Text Options - Display ItemCheck boxThis controls whether the selected text element will be displayed. Set the check box to display the item, clear it to hide it.

Text Options - SampleFont DialogThe Sample column displays a sample of the font style that is currently defined for the selected text item. Double clicking the sample text opens a standard windows font dialog to allow the family, size and style of the font to be set for the selected text item.

Text Options - SpacingInteger value 1 to 20This determines the spacing between the selected text element and the item it describes e.g the spacing between the X-Axis of the isopleth plot and the X-Axis of the graph. The value is expressed as a percentage of the dimensions of the isopleth plot.

Figure 13-16, Font Dialog

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13-24

Calculations 14-1

14-1

Page

14 Calculations

14.1 Calculation Options View . . . . . . . . . . . . . .3

14.1.1 General Tab. . . . . . . . . . . . . . . . . . . . . . . . . . 414.1.2 Sizing Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.1.3 Heat Transfer Tab . . . . . . . . . . . . . . . . . . . . 1014.1.4 Emissions Tab . . . . . . . . . . . . . . . . . . . . . . 1214.1.5 Fitting Tab . . . . . . . . . . . . . . . . . . . . . . . . . . 14

14-2

14-2

Calculations 14-3

Flaresim calculations are started by clicking the Calculate button in the Case View tool bar. Once started Flaresim will calculate the active objects using the settings defined in the Calculation Options view.

The Calculation Options view is accessed by selecting the Calculation Options branch in the Case Navigator view and clicking the View button. Alternatively you can double click the Calculation Options branch.

14.1 Calculation Options View

The Calculation Options view is shown below.

Figure 14-1, Calculation Options View

Calculate Buttons

14-3

14-4 Calculation Options View

Status TextStatus messageThe message displayed in this field and its colour indicates whether the calculation options are complete and the model is ready for calculation.

14.1.1 General Tab

The following data entry fields are found on the General tab of the Calculation Options view (see Figure 14-1).

Calculation Methods - Radiation MethodDrop down list: Flaresim API / Strict API / Point / Diffuse / Mixed / Brzustowski / M.Point Brz / ChamberlainSelects the method to be used to model the thermal radiation from the flame.

The Flaresim API and Strict API methods model the single point source method of Hajek and Ludwig given in API RP-521. The difference between the methods is in the method of calculating the flame shape before finding the centre point to act as the source. The Flaresim API method uses the vector based flame shape method and allows multiple flame elements to be used to model the shape more accurately even though a single, centre point will be used as the source. The Strict API method uses the graphical method presented in API 521 through a curve fit to the data presented there. The API method in DOS versions of Flaresim and Flaresim for Windows versions prior to version 2.0 was the Flaresim API method. Either API method may be generally applied to most flare systems.

The Point source method is a multiple point extension of the API method in which the flame is assumed to be completely transparent such that radiation from one point does not either interfere with or occlude another. The flame is divided into a series of smaller point source elements whose contributions are summed to derive the total radiation from the flame. In practice this method generally gives more realistic and less conservative values than the API method. It does however tend to over predict thermal radiation in the near field.

14-4

Calculations 14-5

The Diffuse source method assumes that the flame is completely opaque such that radiation is emitted entirely from the surface of the flame envelope. This method tends to under predict the thermal radiation in the near field.

The Mixed source method is an empirical combination of both the Point and Diffuse source methods. This has been found to give more realistic results in both the near and far fields.

The Brzustowski method is a single point method in which the flame centre is determined from jet dispersion theory. The method as described in API RP-521 is subject to a number of limitations in its implementation in Flaresim:-

• Only vertical tips may be modelled.• Air assisted flares may not be modelled.• Liquid burners may not be modelled.

The M.Point Brz method is a Flaresim extension to the standard Brzustowski method to allow the number of flame elements and the element position to be specified by the user. In versions of Flaresim prior to 1.2 these options could be set for the Brzustowski method. In Flaresim 1.2 the Brzustowski method is forced to be a single flame element with fixed element position. Old cases that specify the Brzustowski method will be updated automatically to M.Point Brz if they have more than one flame element or the element position is not 50%.

The Chamberlain method, also known in the industry as the Shell Thornton method is based on a modelling the flame as a conical frustum radiating from its surface with a uniform emissive power. The method was developed to provide more accurate predictions of flame shape and radiation in the near field.

Calculation Methods - No of ElementsRange: 1 to 50The number of elements that the flame is divided into for calculation of flame shape and the sources for the Point, Diffuse and Mixed methods. Larger values will generally give more realistic values for the thermal radiation at the expense of calculation time.

14-5


Unless you are modelling a system with a highly distorted flame shape, 25 elements should be more than adequate. The combination of a high flaring rate and an inclined tip flaring into a high wind may require 50 elements to adequately model the flame shape.

Calculation Methods - Element PositionRange: 0 to 100%The element position indicates the source point within a flame element that is used for calculations. Typically this is 50% i.e. the middle of the flame element is taken to be the point source. 0% indicates the source is the start of the element, 100% is the end.

Calculation Methods - Noise MethodDrop down list: API/SpectrumSelects the method to be used for the noise calculations. The API method taken from RP521 is a simple single value method and considers jet noise only. The Spectrum method uses multiple frequency values and includes combustion noise. Generally the Spectrum method is recommended.

Options - Expert ModeCheck boxWhen set this option allows the user to select additional options that have been classified as being for expert use only. These options include:-

1. Allowing the flame length method to be set independently of the calculation method for each Tip - See Tip view.

2. Allowing the plane of orientation to be set for Receptor Points - See Receptor Point view.

3. Allowing the plane of orientation to be set for Receptor Grids - See Receptor Grid view.

4. Allowing the radiation from each tip to be modelled with a different radiation method.

5. Allowing the emissions data for each Tip to be set separately.

14-6

Calculations 14-7

Options - WindchillCheck boxWhen set an empirical correlation is used to correct the incident thermal radiation at any receptor point by taking into account the heat losses due to passage of wind over the point. Use of this option will generally be a matter of individual judgement or your company standards.

It is recommended that you do not use this option if you are interested in the surface temperature calculations. Note that effective of wind on convective heat transfer in the surface temperature calculations is independent of the setting of this option.

Options - Atm. Noise AttenuationCheck boxWhen set a correction will be applied to the noise calculations to allow for the attenuation in noise due to atmospheric absorption. This option should normally be set.

Options - Adiabatic Temp. Corr.Check boxWhen set the temperature of the fluid in the tip or stack riser will be corrected for the calculated pressure at each point. The correction will assume adiabatic compression or expansion from the defined fluid reference pressure to the calculation pressure.

This correction allows more accurate calculation of fluid properties such as density and sonic velocity at different points.

Include Options - R-K Z FactorCheck boxWhen set the fluid compressibility factor or Z factor is calculated using the Redlich Kwong method. If cleared the method used is the Berthelot equation.

The results of the two methods will be similar at low pressures (< 5 bar). At higher pressures the Redlich-Kwong method is more accurate so it is set to be the default method for all new cases from Version 1.1 onwards.

14-7


Buoyancy

For all methods except the Brzustowski and Chamberlain methods, the flame shape is calculated by resolving the velocity vectors in three dimensions. The main components are the tip exit velocity and the wind velocity. There is however an additional velocity component which is due to the density differences between the hot combustion gases and the surrounding air. This is referred to as the flame buoyancy term.

Buoyancy - PipeRange: 0 to 100 m/sThe flame buoyancy which should be used for Pipe flares. A value of 3.0 m/s is recommended unless specific vendor information suggests otherwise.

Buoyancy - SonicRange: 0 to 100 m/sThe flame buoyancy to be used for Sonic flare tips. A value of 4.6 m/s is suggested unless specific vendor information suggests otherwise.

Buoyancy - WelltestRange: 0 to 100 m/sThe flame buoyancy to be used for Liquid flare tips. A value of 0.03 m/s is suggested unless specific vendor information suggests otherwise.

Environment - Active EnvironmentDrop down list: All defined environmentsAllows selection of the set of environmental data to be used for the calculations. This can also be set through activating a specific Environment object.

14-8

Calculations 14-9

14.1.2 Sizing Tab

The following figure shows the Sizing tab of the Calculation Options view.

Stack Sizing - Select StackDrop down list of defined stacksAllows one of the existing stacks to selected for sizing calculations i.e. calculation of the stack length to meet the sizing constraints defined on the active receptor points. To stop the sizing calculations i.e. to do a rating calculation this should be set to None.

Stack Sizing - Minimum LengthRange: 0 to 500 mThe minimum length allowed for the stack being sized.

Stack Sizing - Maximum LengthRange: 0 to 500 mThe maximum length allowed for the stack being sized.

Figure 14-2, Sizing Tab

14-9


Sizing Result - Calculated LengthCalculated value, mThe calculated length of the stack required to meet the sizing constraints. If the sizing calculations fail the value will be blank.

Sizing Result - Wind Speed UsedCalculated value, m/sThe wind speed used to calculate the final stack size. If Wind Rose data has been considered in the sizing calculations, see Environment View then the value may not be the same as the wind speed used to calculate and display the final results.

Sizing Result - Wind Direction UsedCalculated value, angleThe wind direction used to calculate the final stack size. If Wind Rose data has been considered in the sizing calculations, see Environment View then the value may not be the same as the wind direction used to calculate and display the final results.

14.1.3 Heat Transfer Tab

The following figure shows the Heat Transfer tab of the Calculation Options view.

14-10

Calculations 14-11

This view allows definition of coefficients for calculating the heat transfer coefficient as a function of wind speed. Two sets of parameters may be defined to apply above and below a limiting wind speed. The equation is:-

Wind Speed UnitsDrop down List: Speed UnitsThis drop down selects the wind speed units that are appropriate for the A and C constants entered.

Figure 14-3, Heat Transfer Tab

(1)HTC A WindspeedB⋅ C+=

14-11


Transition Wind SpeedRange: 0.01 to 100 m/sThe transition wind speed at which the heat transfer coefficient calculation switches from the first set of defined constants to the second.

There are then two groups of equation parameters, the first apply for wind speeds below the defined transition wind speed, the second when the wind speed is higher than the transition value.

Equation Parameter ARange: 0.01 to 100The constant factor to be multiplied by the wind speed.

Equation Parameter BRange: 0 to 10The power to which the wind speed is raised.

Equation Parameter CRange: 0.01 to 100The constant factor to be added to the heat transfer coefficient.

Temperature Rise Calculation - Exposure TimeRange: 1 to 1,000,000 sThe time over which the rise in surface temperatures is to be calculated.

Time StepsRange: 1 to 1,000The number of calculations to be made between the starting point and the final exposure time. A higher number will track the rise in surface temperature more accurately but it will not normally be necessary to use more than 10 points.

14.1.4 Emissions Tab

The Emission tab defines the default calculation basis and corresponding rate of emissions of NOx, CO and unburnt hydrocarbons to be used for all tip. These values will be used unless

14-12

Calculations 14-13

the Expert Mode option is in use in which case they can be set individually for each Tip on the Emissions Tab of the Tip View.

NOx Emission Rate - BasisDrop down list: Mass/Heat Release / Mass/Mass Flare Fluid / Mass/Mole Flare Fluid / Sintef MethodThis entry defines the basis used to calculate the NOx emission rate for each tip. The NOx emission can be set to a fixed proportion based on the heat release, mass flow or mole (volume) flow of the flared fluid or calculated using a method published by Sintef, see Methods chapter.

NOx Emission Rate - RateRange: 0 to 100, units depend on selected BasisThis entry defines the fixed proportion used to calculate the total emissions of NOx according to the defined Basis. Leave blank if the Sintef calculation basis is selected.

Figure 14-4, Emissions Tab

14-13


CO Emission Rate - BasisDrop down list: Mass/Heat Release / Mass/Mass Flare Fluid / Mass/Mole Flare FluidThis entry defines the basis used to calculate the CO emission rate for each tip. The CO emission can be set to a fixed proportion based on the heat release, mass flow or mole (volume) flow of the flared fluid.

CO Emission Rate - RateRange: 0 to 100, units depend on selected BasisThis entry defines the fixed proportion used to calculate the total emissions of CO according to the defined Basis.

Unburnt HC Emission Rate - BasisDrop down list: Mass/Heat Release / Mass/Mass Flare Fluid / Mass/Mole Flare FluidThis entry defines the basis used to calculate the emission rate of unburnt hydrocarbons for each tip. The unburnt HC emission can be set to a fixed proportion based on the heat release, mass flow or mole (volume) flow of the flared fluid. Note that unburnt hydrocarbons are assumed to be Methane.

Unburnt HC Emission Rate - RateRange: 0 to 100, units depend on selected BasisThis entry defines the fixed proportion used to calculate the total emissions of unburnt according to the defined Basis.

Reset DefaultsButtonClicking this button will reset the Emission Bases and rates to their default values.

14.1.5 Fitting Tab

The Fitting tab provides access to a data fitting process in Flaresim that allows the F Factor for a selected tip to be adjusted to achieve a best fit between the calculated and observed radiation levels at one or more receptor points.

14-14

Calculations 14-15

The data fields that control the fitting process are shown below.

Fitting Parameters - Target TipDrop down ListThis selects the Tip whose F Factor value is to be adjusted to try to match the calculated and observed values of radiation. The list shows all of the tips configured in the model. The tip that is selected must have its F Factor method set to User Defined. It does not matter what starting value of F Factor is defined on the tip.

Fitting Parameters - Target Receptor PointDrop down ListThis selects the Receptor Points which are to be included in the fitting calculation. Either a single point can be selected or the “All Active” option can be selected in which case all Receptor points that are not set to Ignored will be included in the calculation.

Figure 14-5, Fitting Tab

14-15


All of the points included in the calculation must have a value defined for the Observed Radiation field.

Fitting Parameters - ResultCalculated valueThis displays the value for the F Factor that was calculated by the fitting process.

Fitting Parameters - ErrorCalculated valueThis displays the square root of the sum of the square of the relative errors between the calculated and observed radiation values for the selected Receptor points.

Run FittingButtonClicking this starts the fitting process. The fitting process first reconfigures the model to solve for Receptor points only. It will then set the selected Tip to a low F Factor and run the model to calculate the radiation at each selected Receptor point. The sum of the square of the relative errors between the calculated and observed radiation values will then be calculated. The F Factor is then raised by a step and the process repeated until the calculated error begins to rise. At this point a bisection search for the F Factor that gives the minimum value for the error is obtained.

When the value of the F Factor that gives the minimum error has been found the whole model will be reinstated and re-run at the resulting F Factor.

Note if the fitting process is run for a single Receptor Point the final error should always be 0 as long as there is a feasible value for the F Factor which cannot be greater than 1.

14-16

Printing 15-1

15-1

Page

15 Printing

15.1 Report View . . . . . . . . . . . . . . . . . . . . . . . . .4

15.1.1 Report File . . . . . . . . . . . . . . . . . . . . . . . . . . 7

15.2 Output Graphic Report View . . . . . . . . . . . .8

15-2

15-2

Printing 15-3

Output of Flaresim results is through the tool bar Print and Graphic Report buttons or the File-Print and File-Print Graphic

Report menu options.

Selecting the Print option creates a Report view which contains a report of the current input data and results for the case. The Report view allows the contents to be customised by selecting different sections of data input and output. Multiple Report views can be created from the same case as data is changed and the case recalculated to allow for side by side comparison of results. Report views can then be output to a printer or saved as a case.

Selection of the Graphic Reports option opens the Output Graphic Report view which offers selection of the graphic reports to be output and the output method to be used. These views are described below.

Flaresim produces its standard reports through an HTML file which is created by using a style sheet file, by default Flaresim.xsl, to format the contents of the Flaresim model file. The Preferences view allows the user to specify the name of the style sheet file to be used.

Both the Flaresim XML data files and the XSL style sheet file comply with the appropriate W3C.org standards. This provides the capability to reformat the output of Flaresim through definition of an alternate style sheet file. Third party documentation on the use of XSL files should be consulted since this is beyond the scope of this documentation.

Flaresim’s graphic reports are produced through a layout file which is an XML formatted file that describes the text, data and graphical elements to be included in the report and their layout. The default layout file to be used may be selected in the Preferences view or for each receptor grid individually.

15-3

15-4 Report View

15.1 Report View

When the Print button on File-Print menu option is selected a Report view is opened. This requires that the case is saved to a temporary file and there can be a short delay before the report appears.

The Report view is a separate window from the main Flaresim program allowing multiple Report views to be compared side by side as the case is recalculated with different input data. To aid identification of different Reports, the Report view title bar shows the time that the Report was generated and the name of the case that generated it.

Figure 15-1, Report View

15-4

Printing 15-5

Note that the Report view being displayed is of the HTML report file generated by Flaresim. Some elements of this report file will float and be reformatted to try and fit into the area available for display. It may be necessary to expand the view to see the report as it will be printed.

Report ItemTree ViewThis section of the view lists the items that can be included in a report as a tree structure in a similar way to the Case Navigator view. As in the case summary, the and icons can be used to expand and collapse branches of the tree as required. The complete Report Items panel can be collapsed using the button and expanded again using the button.

Include ItemCheck boxEach item available for the report has a check box against it. The check box should be set to include the topic or cleared to exclude it.

Reset OptionsButtonResets the include item check boxes for each item to the defaults contained in the PrintPreferences.xml file.

Clear AllButtonClears the include item check boxes for all items.

Save OptionsButtonOpens a File Save dialog to allow the current report item selection to be saved to a dedicated configuration file. This option can be used to update the default settings in the PrintPreferences.xml file.

Read OptionsButtonOpens a File Open dialog to allow a configuration file contain report item selection to be read and applied to the current case.

15-5

15-6 Report View

Note that whenever a case is saved the current report settings are saved with it. The Save Options and Read Options buttons provide a way for settings copied from one case to another without the need to update the main PrintPreferences file.

Save Report As CaseButtonSince the Report view is independent of a case and because multiple Reports can be generated with different input data, the Save Report As Case allows the information associated with a particular report to be saved as a Flaresim case. Note that all of the case data and results will be saved, not just the current selected items.

RefreshButtonUpdates the report preview to reflect any changes that have been made to the included or excluded topics. The report cannot be refreshed if any data has changed since it was generated.

PrintButtonPrints the report using the current selection of included and excluded items. Clicking this button starts the printing process by displaying the standard Windows Printer dialog view below to allow the user to select the printer to be used and to control the setup of the print options.

15-6

Printing 15-7

Once the printer options have been set the Print button on this view should be clicked to send the output to the printer.

15.1.1 Report File

When a case is saved, the HTML report file and the associated graphic files will be automatically saved at the same time. These files will be saved to a sub-folder in the folder to which the case is being saved. The sub-folder name will be the same as the saved file name.

This HTML file can be viewed at any time using an internet browser, independently of Flaresim.

Figure 15-2, Print Dialog

15-7

15-8 Output Graphic Report View

15.2 Output Graphic Report View

When the button or File-Print Graphic Reports menu option is selected displays the Output Graphic Report view to allow selection of the graphic reports to be output and whether these are to be output to printer or to a file. The Output Graphic Report view is shown below. This is a modal view that does not allow use of other parts of the Flaresim program until it is closed.

SelectList Box: Receptor Grids, Receptor Points, DispersionsThis displays as list of the Receptor Grids, Receptor Points and Dispersion objects for which a graphic report is available. Receptor Points only appear in the list if a wind rose graphic report is available. Dispersion objects only appear in the list when a contour plot report is available.

Figure 15-3, Output Graphic Report View

15-8

Printing 15-9

Objects are selected in the list by clicking on the name in the list. Multiple items may be selected using Shift-Click and Ctrl-Click in the usual way.

For convenience an All option is provided at the top of the list which can be selected to output graphic reports for all the receptor grids and receptor points in the model.

Select PlotsCheck boxesEach receptor grid can generate four separate graphic reports, one for each of the radiation, noise, temperature isopleths and concentrations (as long as jet dispersion calculations are enabled). These check boxes allow selection of which reports will be output. Set a check box to output the associated report and clear a check box to suppress the report.

Save File TypeDrop down list: JPG / PNG / BMP / WMF / EMFThis allows selection of the graphic file type that will be generated if the reports are output to file using the Save Graphic Reports button. The options are JPG, PNG or BMP bitmap files and WMF or EMF vector meta files.

Save Graphic ReportsButtonThis creates the selected graphic reports and saves them as files of the type selected by the Save File Type item. A pop-up window will be displayed to select the output folder. Each file will be automatically named with the type of the isopleth and the name of the receptor grid e.g. Radiation-Helideck. Confirmation of each file saved is output to the information log.

Isopleths To CSVButtonThis saves a list of the isopleth data points for each selected report to a text file in Comma Separated Value or CSV format. This allows the isopleths to be plotted using third party applications such as Excel. A pop-up window will be displayed to select the output

15-9


folder. Confirmation of each file saved is output to the information log.

Isopleths To XMLButtonThis saves a list of the isopleth data points for each selected report to a text file in XML format. A pop-up window will be displayed to select the output folder. Confirmation of each file saved is output to the information log.

Isopleths To DXF ScriptButtonThis creates and saves an Autocad script that will allow the isopleth data for each selected report to be imported into a plot plan or other drawing using Autocad or compatible software such as Intellicad. A pop-up window will be displayed to select the output folder. The files will be stored with a .scr extension in the selected folder. Confirmation of each file generated is output to the information log.

The script generated will create one new layer in the target drawing file for each isopleth value defined. Each layer will be named according to the isopleth value and the isopleth value will also be displayed on a text label within the added layer. An additional layer will be created to draw the flame location. Note that the generated script requires that the “Snap to guides” features of Autocad are turned off before playing the script.

Print Graphic ReportsButtonThis button prints the selected graphic reports to the currently selected printer. The Print dialog view shown below will be displayed to allow the printer to be selected.

15-10

Printing 15-11

Preview Graphic ReportsButtonThis button generates a preview of the selected graphic reports and displays it in the Preview Graphic Reports view shown below.

Figure 15-4, Printer Dialog

Figure 15-5, Preview Graphic Reports View

15-11


This view allows output pages to be reviewed and page settings adjusted. The Print button in the view can then be clicked to send the output to the printer or the Save button can be used to save the output to a PDF file.

CloseButtonThis button closes the Output Graphic Report view and returns to the main Flaresim views.

15-12

Calculation Methods 16-1

16 Calculation Methods

Page14.1 Thermal Radiation . . . . . . . . . . . . . . . . . . . .5

14.1.1 API Method . . . . . . . . . . . . . . . . . . . . . . . . . . 514.1.2 Integrated Point Source Method. . . . . . . . . 614.1.3 Integrated Diffuse Source Method . . . . . . . 714.1.4 Integrated Mixed Source Method . . . . . . . . 714.1.5 Brzustowski and Sommer Method . . . . . . . 814.1.6 Atmospheric Attenuation . . . . . . . . . . . . . . 814.1.7 Windchill . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.1.8 Flame Shape . . . . . . . . . . . . . . . . . . . . . . . . 10

14.2 Surface Temperature . . . . . . . . . . . . . . . . .16

14.3 Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

14.3.1 Combustion Noise . . . . . . . . . . . . . . . . . . . 1814.3.2 Jet Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . 1914.3.3 Atmospheric Attenuation . . . . . . . . . . . . . 22

14.4 Nomenclature . . . . . . . . . . . . . . . . . . . . . . .24

14.4.1 Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . 2414.4.2 Subscripts. . . . . . . . . . . . . . . . . . . . . . . . . . 25

14.5 Purge Gas . . . . . . . . . . . . . . . . . . . . . . . . . .26

14.5.1 HUSA Method . . . . . . . . . . . . . . . . . . . . . . . 2614.5.2 Reduced HUSA Method. . . . . . . . . . . . . . . 27

16-1


Page14.6 Water Sprays . . . . . . . . . . . . . . . . . . . . . . .29

14.6.1 Thickness of Water Curtain . . . . . . . . . . . 30

14.7 References . . . . . . . . . . . . . . . . . . . . . . . . .31

16-2


16-3

16-4

This chapter contains a summary of the mathematical models used for the calculation of incident thermal radiation, noise and surface temperatures. It is not intended to be a detailed treatise on combustion theory, but rather a summary of the models available in the program to assist the engineer in making his own judgement as to the applicability of the models to his particular system.

16-4


16.1 Thermal Radiation

5 options are available for calculating the incident thermal radiation at a point receptor. These are:-

• API Method• Integrated Point Source• Integrated Diffuse Source• Integrated Mixed Source• Brzustowski and Sommer

These methods primarily differ in the approach to the calculation of the contributions of individual elements within the flame to the total incident heat flux and the method for calculation of the flame shape.

Each of these methods can be used for most applications either as preferred by the program user or as required by client preference and specifications. The predicted thermal radiation values may be corrected for a range of environmental conditions. These corrections are available for:

• Windchill• Atmospheric attenuation

The inclusion of the attenuation effects due to windchill or atmospheric attenuation must be either a matter of sound engineering judgement or as required by client specifications.

All thermal radiation values calculated by any of these methods are to point receptors and do not take account the relative orientation of the receptor to the flame.

16.1.1 API Method

This is based upon the simple heat release method outlined in API RP-521, "Guide For Pressure Relieving and Depressuring Systems",

16-5

16-6 Thermal Radiation

1997 [1]. This method uses Equation 1 proposed by Hajek and Ludwig [2] to evaluate the flux at a given distance from the flame.

It is assumed that the flame can be treated as a single point source located at the centre of the flame which radiates in all directions from this centre.

There are two variants of the API method implemented in Flaresim. In the Flaresim API method the flame shape is calculated from the resolution of the velocity vectors for the flared fluid, wind and flame buoyancy. Multiple flame elements can be defined to model the flame shape more accurately but the source is still modeled as a single point at the centre. In the Strict API method, the flame shape is calculated using the graphical method described in the API RP-521 implemented using a data fit to the curves presented in the guide. Integrated Point Source Method.

The integrated point source method is an extension to the API method in which the flame is divided into a series of smaller point source elements whose contributions are summed to derive the total thermal radiation from the flame. The centre of each of the elements is used for the calculation of the distance between the flame element and the target receptor.

Two major assumptions are made:

• The flame radiates uniformly along its entire length.• The flame is long in comparison to its width. As such it may be

considered to be a line source.

In making these assumptions, it is accepted that the flame itself is completely transparent to thermal radiation and that one point source does not either interfere with or occlude another. This occlusion effect would generally be negligible to the side of the flame but could be significant at locations directly below the flame where there is a shallower angle of view.

(1)KFQ

4πD2

--------------=

16-6


These assumptions lead to Equation 2 as proposed by McMurray[4].

The distance between the point source and the receptor is calculated from a flame shape derived from the resolution of the velocity vectors for the flared fluid, wind and flame buoyancy.

16.1.2 Integrated Diffuse Source Method

The diffuse source model assumes that the flame itself is completely opaque such that the thermal radiation is emitted entirely from the surface of the flame.

This model is represented by Equation 3.

The distance between the point source and the receptor is calculated from a flame shape derived from the resolution of the velocity vectors for the flared fluid, wind and flame buoyancy.

16.1.3 Integrated Mixed Source Method

The mixed source model is basically a combination of the point and diffuse source models. This was developed as a result of observations during field tests [4] that showed:

• The Integrated Point Source (IPS) model tends to over predict the thermal radiation close to the flare.

• The Integrated Diffuse Source (IDS) model tends to under pre-dict the thermal radiation close to the flare.

(2)

(3)

KipsFQ4πL---------- 1

D2

------- ld0

L

=

KidsFQ

π2L

--------- βsin

D2

----------- ld0

L

=

16-7


• Both models predict similar values for thermal radiation in the far field.

The thermal radiation for the mixed source model is calculated by Equation 4 which is a linear combination of the IPS and IDS models.

16.1.4 Brzustowski and Sommer Method

The equation for the calculation of the heat flux at a given distance is identical to that given for the API method as Equation 1. Both this method and the API method are based upon the flame being considered as a single point heat source.

The distance between the point source and the receptor is calculation from a flame shape which is based upon the diffusion of a turbulent jet to the to the lean flammability concentration limit [3].

Flaresim allows an extension to the standard Brzustowski method by allowing the user to specify multiple flame elements or an element position that is not 50%. In versions of Flaresim prior to 1.2 these options could be set for the Brzustowski method. In Flaresim 1.2 and following these options can only be set if the extended M.Point Brzustowski method is selected.

16.1.5 Atmospheric Attenuation

Brzustowski and Sommer[3] recommend the use of the atmospheric transmissivity, as the fraction of the heat intensity which is transmitted to a point, in order to correct the calculated values for thermal radiation.

This correction is given by Equation 5.

(4)

(5)

Kims aKips 1 a–( )Kids+=

Kτ τ K⋅=

16-8


In all cases, atmospheric absorption attenuates the incipient radiation at a point. This will typically be 10 to 20 % over distances of up to 500 ft. The empirical Equation 6 given below was obtained by cross plotting absorptivities calculated from Hottel charts. It is strictly applicable only under the following conditions of:

• A luminous hydrocarbon flame radiating at 2240 F

• Dry bulb temperature of 80 F• Relative humidity greater than 10%• Distances from flame between 100 and 500 ft

It is generally used to estimate the order of magnitude of the atmospheric transmissivity under a wider range of conditions.

Equation 6 should prove adequate for most situations. However, for cases in which the design conditions are significantly different from those under which the equation was derived, the designer should revert to the Hottel charts.

16.1.6 Windchill

The design of offshore flare systems often takes into account the effect of heat loss from the target surface due to windchill. Equation 7 gives the simple correction to the calculated value for thermal radiation.

The correction is taken from Figure 16-1 below. For conditions beyond the range of this figure, the following constraints are applied:-

• If the windspeed is greater than 35 knots, the 35 knot value is used.

(6)

(7)

°°

τ 0.79100D

---------0.0625 100

H---------

0.0625⋅=

Kw K Kf–=

Kf

16-9


• If the ambient temperature is less that 30 F, the 30 F value is used.

• If the ambient temperature is greater than 80 F, the correction is taken to be zero regardless of the windspeed.

16.1.7 Flame Shape

The calculation of the distance between any point on the flame and the target receptor requires a knowledge of the flame length and shape. This is a function of:

• Flare exit velocity• Wind speed and direction• Orientation of the tip

Figure 16-1, Windchill Correction

° °

°

16-10


The flare exit velocity is calculated by simply dividing the volumetric flare rate by the cross sectional area of the flare tip according to Equation 8.

The gas mach number is calculated from the sonic velocity which is calculated from Equation 9.

The method for calculation of the flame length and deflection is dependent upon the method selected for calculation of the thermal radiation. If the API, IPS, IDS or IMS method is selected then the flame length is calculated from the heat released by the flame, then the deflection is calculated by resolving the vectors for the jet, flame buoyancy and wind.

The flame length is calculated from an empirical equation relating the flame length to the heat release. The heat release is the total heat produced by the combustion of the fluid. This is given by Equation 10.

The flame length is calculated from Equation 11. The constants l1 and l2 are a function of the type of tip

(8)

(9)

(10)

(11)

uj4WZRT

PMπd2

-------------------=

usgkRT

M-------------=

Q W LHV⋅=

L I1QN----

I2

=

16-11


Steam and air assisted flares will generally have shorter flames than those calculated by these equations. The program contains proprietary algorithms for prediction of the shortening of the flame as a function of the rate of injection of the assist fluid. Due to the proprietary nature of these algorithms, they are not presented here.

In windy conditions the flame will be distorted from the straight vertical. This distortion may be calculated by the resolution of the velocity vectors for the exit jet, wind and flame buoyancy.

The jet velocity as a function of the curvelinear distance along the flame is modelled according to the formula proposed by McMurray[4].

Equations 13, 14 and 15 are resolved according to the Cartesian coordinate system shown by Figure 16-2.

Tip Type l1 l2

Pipeflare 0.00331 0.4776

Single Burner Sonic 0.00241 0.4600

Multiple Burner Sonic 0.00129 0.5000

(12)

(13)

(14)

(15)

ul 5.0ujd1l--- 1

A---–=

dxdt------ ul Φ ω u∞ ψcos+cossin=

dydt------ ul Φ ω u∞ ψsin+cossin=

dzdt----- ul Φ ub+cos=

16-12


If the Brzustowski method is selected then the flame length and deflection are calculated from a method based upon the distance required for the dilution of the flared gas to the lean flammability limit concentration.

Dimensionless parameters are defined which relate the lean flammability limit concentration and the following parameters to the deflection of the end point of the flame:

• Tip exit velocity• Wind velocity• Gas molecular weight• Air molecular weight• Tip diameter

The following dimensionless parameters are defined:

Figure 16-2, Coordinate System

(16)cl cl

uj

u∞------

Mj

M∞--------⋅=

16-13


Figure 16-3 gives the values for the horizontal and vertical distance factors for a range of values for the dimensionless concentration parameter..

(17)

(18)

Figure 16-3, Dimensionless Distance Parameters

xl

xl

djuj

u∞---------

ρj

ρ∞-------⋅

--------------------------=

zl

zl

djuj

u∞---------

ρj

ρ∞-------⋅

--------------------------=

16-14


This procedure cannot strictly be used for calculation of the flame deflection in cases where there is no wind. The limiting case is a ratio of gas exit velocity to wind velocity of 110. This value corresponds to a sonic discharge of methane at 400 F into a 10 mph wind. When analysing any calculation results this ratio should be checked if you are evaluating the effect of low wind speeds.

°

16-15

16-16 Surface Temperature

16.2 Surface Temperature

The equilibrium surface temperature of metal surfaces exposed to the thermal radiation is calculated from a heat balance between the thermal radiation from the flame incident at the specified point and the heat losses from the same point.

This heat balance equation assumes that heat losses by convection and radiation occur only from the surface exposed to the radiation.

The overall heat loss from the point is the sum of the radiation from the point and the forced/free convection from the point. The radiative heat transfer coefficient is given by:

Convective heat transfer coefficients are calculated from a series of empirical correlations that are a function of air velocity.

A value of 0.70 is used for both the absorbtivity and emissivity of the surface. This is a typical value for steels.

(19)

(20)

(21)

(22)

Kα hc hr+( ) Tm T∞–( )⋅=

hr σETm

4T∞

4–( )

Tm T∞–( )------------------------------⋅=

0 u∞ 15≤ ≤

hc 0.80 0.22u∞+=

u∞ 15>

hc 0.56u∞0.75

=

16-16


16.3 Noise

The noise generated by a flare may be broken down into 3 basic components:

• Combustion noise• Jet noise

Although the noise may be expressed in terms of an average value, it is frequency dependant. The shape of this noise spectrum is dependant upon whether the major contribution is due to combustion noise as in the case of pipeflares, or jet noise as in the case of sonic flares. The noise spectrum is generally given in 7 octave bands from 63 Hz to 8000 Hz.

Attenuation of the noise occurs due to atmospheric absorption. This absorption is a function of the frequency of the noise with higher frequencies being more readily absorbed.

Noise is expressed either in terms of the Sound Power Level (PWL) or the Sound Pressure Level (SPL) where these terms are defined by Equations 23 and 24.

The international standard reference conditions are 10-12 Watts (W0) and 2 x 10-6 N/m2 (P0).

In the case of a flare stack where the acoustic source may be considered to be in a free field with directivity factor of unity then

(23)

(24)

PWL 10WW0------- log=

SPL 10P

2

P02

---------

log=

16-17

16-18 Noise

the Sound Pressure Level is related to the Sound Power Level by Equation 25.

Noise data predicted by the program refer to the Sound Pressure Level in all cases.

16.3.1 Combustion Noise

Combustion noise is a function of the heat release from the flame and the design of the flare tip. The calculation of the noise spectrum due to combustion is based upon a typical characteristic curve for the type of tip under consideration (pipe, sonic etc). An example of the shape is given by Figure 16-4 which gives the noise levels at a distance of 20 ft from a combustion source of power 81 MM btu/hr.

The noise level at each frequency is then corrected for the actual combustion duty and distance from Equation 26.

(25)

(26)

SPL PWL 20 Dlog 0.49– SPLA––=

SPL SPL20 10Q

81 106×

---------------------

2020D------ SPLA–log

+log+=

16-18


16.3.2 Jet Noise

The expansion of an unchoked gas stream will produce noise whose sound power at the peak frequency is determined from the kinetic energy and acoustic efficiency of the expanded jet according to Equation 27 [6].

The acoustic efficiency of the expanded jet is related to the jet velocity and whether or not the flow is choked.

Figure 16-4, Typical Noise Combustion Spectrum

(27)PWL ηVρjuj

2

2------------=

16-19

16-20 Noise

If the flow is not choked, then the acoustic efficiency may be obtained from Figure 16-5. In this figure the dimensionless factor B is given by the equation:

If the flow is choked, then the acoustic efficiency may be obtained from Figure 16-6.

(28)

Figure 16-5, Acoustic Efficiency For Normal Flow

Bρj

ρ∞-------

Tj

T∞------- 2

⋅=

16-20


The expansion of a gas stream will produce noise which has a spectrum which peaks with a frequency calculated by a method due to MacKinnon [6].

At frequencies other than the peak frequency the noise is calculated using Equation 30.

Figure 16-6, Acoustic Efficiency For Choked Flow

(29)fmax

0.2mus

dj-----------------=

16-21

16-22 Noise

16.3.3 Atmospheric Attenuation

At distances greater than approximately 100 ft, the noise becomes attenuated due to absorption by the atmosphere. The attenuation is a function of the frequency of the noise, with higher frequencies being more readily attenuated than lower ones.

Figure 16-7 gives the attenuation of noise for a range of frequencies. This figure is strictly applicable only to still air at a temperature of 70 F and a relative humidity greater than 60%. Extension to temperatures in the range 40 F to 100 F may be made by increasing the attenuation by 10% for each 10 F below 70 F.

(30)

SPLi SPLtot 10

1fi

2fmax-------------- 2

+

1fmax

2fi----------- 4

+

log

⋅–

5.3–

=

°° °

° °

16-22


Figure 16-7, Atmospheric Attenuation Of Noise

16-23

16-24 Nomenclature

16.4 Nomenclature

The following nomenclature is used in sections 16.1 through to 16.3.

16.4.1 Symbols

API flame length (ft)Empirical constant used in IMS methodDimensionless scaling parameterFlammability lean limit concentrationDistance from flame midpoint to receptor (ft)Tip diameter (ft)Metal surface emissivityFraction of heat radiatedFrequency (Hz)Relative humidity (%)Heat transfer coefficient (btu/hr/ft2/(R)Flame length (ft)Lower heating value (btu/lb)Curvelinear flame length (ft)Constant in flame length equationConstant in flame length equationMolecular weightMach numberNumber of burners in tip assemblyThermal radiation at receptor (btu/hr/ft2)Heat capacity ratioPressure (psia)Sound Power Level (W)Heat release based upon LHV (btu/hr)Universal gas constantSound Pressure Level (dB)Temperature ((R)Velocity (ft/s)Volumetric flow (ft3/s)Flowrate (lb/hr)Distance north of tip (ft)

AaBcDdEFfHhLLHVll1l2MmNKkPPWLQRSPLTuVWx

16-24


Horizontal plume distance factorDistance east of tip (ft)Compressibility factor (-)Vertical plume distance factorDistance above tip (ft)Metal surface absorbtivityAngle between flame tangent and line of sight to receptor (degrees)EfficiencyRotation of flare from x axis (degrees)Angle of tip from vertical (degrees)Rotation of wind from x axis (degrees)Fluid density (lb/ft3)Stephan Boltzman constant (0.171 x 10-8 btu/hr/ft2/(R4)Transmissivity

16.4.2 Subscripts

Atmospheric attenuationBuoyancyConvectiveCorrectionFrequency bandIntegrated diffuse sourceIntegrated mixed sourceIntergrated point sourceJet exitCurvelinear lengthMetalRadiativeSonicCorrected for windchillWind/atmosphericCorrected for transmissivityReference conditionAt 20 ft from source

x'yZz'zαβ

ηωΦψρστ

Abcfiidsimsipsjlmrsw∞τ020

16-25

16-26 Purge Gas

16.5 Purge Gas

This section details the different methods used to calculate purge gas rates.

16.5.1 HUSA Method

The full HUSA method is based on the following equation 31[8].

where

Purge rate (ft3/h)Stack diameter (in)% oxygenDepth into stack (ft)Gas buoyancy factor

The gas buoyancy factor is calculated using either equation 32 or 33.

Where composition of purge gas is known, equation 32 is used[8].

where

Volume fraction of ith componentMolecular weight of ith component

(31)

(32)

Qp 0.07068d3.46 1

y--- 20.9

O2----------ln Fb=

QpdO2yFb

Fb

Fb Ci0.65

0.065 29 Mi–( )[ ]exp

i=

CiMi

16-26


Where only the molecular weight of the purge gas is known, equation 33 is used[9].

where

Molecular weight of purge gas.

If the purge gas buoyancy factor calculated using either method is less than the buoyancy factor of nitrogen then the buoyancy factor for nitrogen is used.

16.5.2 Reduced HUSA Method

The reduced HUSA method is based on the following equation 34.[8]

(33)

(34)

Fb 6.25 1 0.75 M 28.96⁄( )1.5–[ ]=

M

Qp 0.003528d3.46

Ci0.65

Ki

i=

16-27

16-28 Purge Gas

where

Purge rate (ft3/h)Stack diameter (in)Volume fraction of ith componentConstant for ith component from following table

If the sum of the terms is less than the value for nitrogen then the value for nitrogen is used.

Component K

Hydrogen 5.783

Helium 5.078

Methane 2.328

Nitrogen 1.067 (no wind)

1.707 (wind)

Ethane -1.067

Propane -2.651

Carbon Dioxide -2.651

Butane and heavier -6.586

QpdCiKi

Ci0.65

Ki K

16-28


16.6 Water Sprays

The modelling of water sprays used for shields is based on the method presented by Long and Rogers [10].

The transmissivity of the water curtain is given by the ratio

where

TransmissivityTotal transmitted fluxTotal black body radiated flux

The total transmitted flux is calculated by integration over the range of radiation wavelengths emitted by the flame.

where

Black body radiation at wavelength , W/m2Radiation wavelength, mAbsorption coefficient at wavelength m-1Thickness of water curtain layer m

The black body radiation at wavelength is given by the Planck equation.

(35)

(36)

(37)

τ EEb------=

τEEb

E Eλb α– λ s⋅( )expλmin( )

λmax

=

Eλb λλαλ λs

λ

Eλb 2πHc2λ 5–( ) Hc( ) KλT( )⁄ 1–( )exp( )⁄=

16-29

16-30 Water Sprays

where

Planck constant J/sSpeed of light m/s2Wavelength of radiation mBoltzman constant J/KTemperature K

The absorption coefficient for water is calculated by interpolation from graphical data presented in the paper [10].

16.6.1 Thickness of Water Curtain

The effective thickness of a water curtain is calculated for a given water flow and nozzle characteristics using an equation presented by Long, [11].

where

Layer thickness mNozzle diameter mNozzle exit velocity m/sDroplet velocity m/s

(38)

HcλKT

s 0.5Dnoz( ) π⁄( )6unoz

udrop--------------=

sDnozunozudrop

16-30


16.7 References

1. API RP521, “Guide For Pressure-Relieving and

Depressuring Systems”, 4th ed, American Petroleum Institute, Washington DC, 1997.

2. Hajek, J.D. and Ludwig, E.E., “How To Design Safe Flare Stacks”, Part 1, Petro/Chem Engineer, 1960, Vol 32, No. 6, pp.C31-C38; Part2, Petro/Chem Engineer, 1960, Vol 32, No. 7, pp.C44-C51.

3. Bruztowski, T.A. and Sommer, E.C. Jr., “Predicting Radiant Heating From Flares”, Proceedings - Division of Refining, Vol. 53, pp. 865-893, American Petroleum Institute, Washington DC, 1973.

4. McMurray, R., “Flare Radiation Estimated”, Hydrocarbon Processing, Nov. 1982, pp. 175-181.

5. Narasimhan, N.D., “Predict Flare Noise”, Hydrocarbon Processing, April 1986, pp. 133-136.

6. MacKinnon, J.G., “Recent Advances in Standardizing Valve Noise Prediction”, Society of Instrument & Control Engineers, Tokyo, Sept. 1984.

7. Husa, H.W., “How to Compute Safe Purge Rates”, Hydrocarbon Processing, 1964, 43, No. 5.

8. Husa, H.W., “Purging Requirements of Large Diameter Stacks”, American Petroleum Institute, Fall Meeting 1977.

9. Shore, D, “Making the Flare Safe”, Journal of Loss Prevention Process Industry, 1996, Vol 9, No 6, 363-381

10. Long, C.A and Rogers M.C, “Temperature Prediction for Surfaces Exposed to Flare Radiation and Attenuation of Radiative Fluxes by Water Curtain”, 5th International Conference - ‘Offshore Structures - Hazard & Integrity Management’ 4-5th December 1996.

16-31

16-32 References

11. Long C.A. “Attenuation of Thermal Radiative Heat Fluxes by Water Curtain”, 1995, School of Engineering, University of Sussex, Report No 95/TFMRC/181.

16-32

Graphic Report Layout A-1

A-1

Page

A Graphic Report Layout

A.1 Introduction to XML . . . . . . . . . . . . . . . . . . .4

A.1.1 Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4A.1.2 Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . 5A.1.3 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

A.2 Layout File Structure . . . . . . . . . . . . . . . . . .6

A.2.1 Allowed Elements . . . . . . . . . . . . . . . . . . . . 6A.2.2 PageSize Element . . . . . . . . . . . . . . . . . . . . 7A.2.3 Text Element . . . . . . . . . . . . . . . . . . . . . . . . . 7A.2.4 Unit Element . . . . . . . . . . . . . . . . . . . . . . . . . 8A.2.5 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8A.2.6 Logo Element . . . . . . . . . . . . . . . . . . . . . . . 14A.2.7 CaseData Element . . . . . . . . . . . . . . . . . . . 14A.2.8 Line Element. . . . . . . . . . . . . . . . . . . . . . . . 15A.2.9 PlotArea Element . . . . . . . . . . . . . . . . . . . . 16A.2.10 LegendArea Element . . . . . . . . . . . . . . . . . 20A.2.11 ContourSet Element. . . . . . . . . . . . . . . . . . 22

A-2

A-2


The appearance of graphic reports produced by Flaresim is controlled by layout files. These files contain a list of instructions in a XML format that describe how data items, graphic items, background text, background lines and background graphics will appear on the report. This appendix describes the format of the layout files.

A-3

A-4 Introduction to XML

A.1 Introduction to XML

XML is a standardised markup language for describing structured data. The following description of the language is intended to introduce the terms used in this appendix. For a full description of the XML standard see http://www.w3.org/xml.

The figure below shows a fragment of the XML language taken from one of the Flaresim layout files.

The basic building block of a XML file is the element. An element is a data fragment that has a tag, attributes and data.

A.1.1 Tags

An element’s tag can be thought of as its name. A tag enclosed in a pair of “< >” brackets starts the description of an element and the same tag preceded by a / character and enclosed in a pair of “< >” brackets ends the description of the element. For example, an element containing text data might be given the tag Description and would appear as follows

<Description>The descriptive text</Description>.

A XML file can contain more than one element with the same tag describing repeating data items. Tags are case sensitive, i.e. <description> is different to <Description>.

Taking the XML fragment shown in Figure A-1 as an example, there are six elements in total with four unique tags namely <Text>, <Logo>, <CaseData> and <Var>. There are three <Text> elements.

Figure A-1, XML File Fragment

A-4


A.1.2 Attributes

The attributes of an element can be thought of as data parameters or additional descriptions of the element. Attributes are defined within the “< >” brackets of the elements opening tag. A single attribute is introduced by a name followed by an “=” sign followed by the value of the attribute enclosed in quotes. For example our Description tag might be extended to have an attribute called Font to define the typeface to be used to print it thus.

<Description Font=”Arial”>The descriptive text</Description>

An element may have no attributes or multiple attributes. Attribute names are case sensitive i.e. Font is different to font.

Taking the XML fragment shown in Figure A-1 as a further example, the <Text> elements there each have four attributes name X, Y, Font and Size.

A.1.3 Data

The data part of an element is contained between the opening tag and the closing tag. The data can be either text or another element. In our <Description> element example the data is the text “The descriptive text”.

The data part of an element does not have to contain data, it can be empty if for example all of the data contained in an element is described through attributes. When the data part of an element is empty the closing “/” character can be included in the opening tag and the closing tag omitted thus.

<Description Font=”Arial”/>

Looking at our example XML fragment shown in Figure A-1 again, we can see that the data sections of the <Text> elements contain descriptive text, the data section of the <Logo> element contains a file name and the data section of the <CaseData> element contains another element introduced by the <Var> tag.

A-5

A-6 Layout File Structure

A.2 Layout File Structure

A Flaresim graphic report layout file must contain the following top level data elements in order to be recognised as a valid graphic report layout file

<?xml version="1.0" encoding="ISO-8859-1" ?>

This defines the version of the XML standard used to encode the file and the unicode character set used. This is a standard element that must appear as the first element in the file.

<FlaresimLayout>

This element is the top level data element that contains all other elements that define the layout of the graphic report.

A.2.1 Allowed Elements

The following element tags are recognised within the main <FlaresimLayout> element within the layout file. Each of these elements is described in more detail below.

Element Tag Description Number

PageSize Defines the overall dimensions Single

Text Defines background text Multiple

Unit Defines units of measurement Multiple

Data Defines data items Multiple

Logo Defines background graphics items Multiple

CaseData Defines case description items Multiple

Line Defines background lines Multiple

PlotArea Defines plot area and style Single

LegendArea Defines plot legend area and style Single

ContourSet Defines contour list and styles Single

A-6


A.2.2 PageSize Element

DescriptionDefines the overall size of the plot to be produced.

AttributesX Size of plot in X dimension in mm.Y Size of plot in Y dimension in mm.

Data ValueNone.

A.2.3 Text Element

DescriptionDefines individual items of background text to appear on the plot such as titles and headings.

AttributesX Required - X position in mm of the left edge of the

textY Required - Y position in mm of the centre line of the

textFont Required - Integer denoting font to be used -

0 = Arial1 = Courier2 = Times Roman

Size Required - Value defining text height as % of plot page height

Style Optional - Text describing style of text - BoldItalicBoldItalic

Data ValueThe background text to be added to the plot.

A-7


A.2.4 Unit Element

DescriptionDefines individual items of unit of measurement text to appear on the plot.


unit textY Required - Y position in mm of the centre line of the

unit textFont Required - Integer denoting font to be used -


Size Required - Value defining unit text height as % of plot page height

Style Optional - Text describing style of unit text - BoldItalicBoldItalic

Data ValueThe name of the unit of measurement type to be output e.g. length, temperature. The full list of recognised type names is the same as the list of quantity names defined in the units.xml file as follows-

time, length, mass, temperature, sound, frequency, surface_area, volume, force, small_length, energy, pressure, velocity, plane_angle, fraction, percentage, power, mass_flow, mass_heat_capacity, mass_energy, heat_flux_density, heat_transfer_coefficient, mass_per_area, mass_density, volume_flow.

A.2.5 Data

DescriptionDefines individual data items that will appear on the plot.

A-8



data valueY Required - Y position in mm of the centre line of the

valueFont Required - Integer denoting font to be used -


Size Required - Value defining data value height as % of plot page height

Style Optional - Text describing style of data value - BoldItalicBoldItalic

Data ValueA <Var> data element defining the data item to be output as follows.

A.2.5.1 Var Element

DescriptionIdentifies individual data item.

AttributesStack Optional - index of stack which variable is associated

with.Tip Optional - index of tip which variable is associated

with. Note this is the index of the tip on the specified stack i.e. a Tip index value of 1 denotes the first tip on the specified stack regardless of whether the tip is the first listed in the model.

A-9


Data Value

A text string identifying the data item to be output. The list of data identifiers recognised is as follows.

Identifier Stack Id Tip Id

WindSpeed Not specified Not specified

WindDirection Not specified Not specified

SolarRadiation Not specified Not specified

Transmissivity Not specified Not specified

Humidity Not specified Not specified

BackgroundNoise Not specified Not specified

TransmissivityMin Not specified Not specified

TransmissivityMax Not specified Not specified

AtmTemperature Not specified Not specified

AtmPressure Not specified Not specified

CalculationMethod Not specified Not specified

NumberOfElements Not specified Not specified

BuoyancyPipe Not specified Not specified

BuoyancySonic Not specified Not specified

BuoyancyWellTest Not specified Not specified

OptSolarRadiation Not specified Not specified

OptWindchill Not specified Not specified

OptBackgroundNoise Not specified Not specified

OptAtmNoiseAttenuation Not specified Not specified

OptAdiabaticTempCorr Not specified Not specified

OptRKZFactor Not specified Not specified

NoiseCalcMethod Not specified Not specified

A-10


Name Required Not specified

Length Required Not specified

AngleToHorizontal Required Not specified

AngleToNorth Required Not specified

Name Required Required

Type Required Required

NbrOfBurners Required Required

Length Required Required

Diameter Required Required

BurnerOpening Required Required

ContractionCoefficient Required Required

ExitLossCoefficient Required Required

Roughness Required Required

OutletPressureSpec Required Required

SealType Required Required

AngleToHorizontal Required Required

AngleToNorth Required Required

Fluid Required Required

MassFlow Required Required

LHV Required Required

MW Required Required

CpCv Required Required

EmissivityMethod Required Required

Emissivity Required Required

Temperature Required Required


A-11


RiserDiameter Required Required

NoiseMethod Required Required

NoiseSPL Required Required

PeakFrequency Required Required

CombustionEfficiency Required Required

ExitVelocity Required Required

MachNumber Required Required

VolumeFlow Required Required

HeatRelease Required Required

FlameLength Required Required

APIFlameLength Required Required

TipExitPressure Required Required

TipInletPressure Required Required

TipDP Required Required

SealInletPressure Required Required

SealDP Required Required

StackInletPressure Required Required

StackDP Required Required

TotalTipExitPressure Required Required

TotalTipInletPressure Required Required

TotapTipDP Required Required

TotalSealInletPressure Required Required

TotalSealDP Required Required

TotalStackInletPressure Required Required

TotalStackDP Required Required


A-12


PurgeFluid Required Required

PurgeFixVolFlow Required Required

PurgeHUSAO2 Required Required

PurgeHUSAHeight Required Required

PurgeFixedVel Required Required

PurgeFixVelCalcFlow Required Required

PurgeFixVolFlowCalcVel Required Required

PurgeFixVolFlowCalcFlow Required Required

PurgeHUSACalcVel Required Required

PurgeHUSACalcFlow Required Required

PurgeRedHUSACalcVel Required Required

PurgeRedHUSACalcFlow Required Required

Fluid2 Required Required

MassFlow2 Required Required

LHV2 Required Required

MW2 Required Required

CpCv2 Required Required

Temperature2 Required Required

AssistFluid Required Required

AssistFluidMassFlow Required Required

AssistFluidFlowRatio Required Required


A-13


A.2.6 Logo Element

DescriptionDefines individual graphic files to be output on the plot. This is usually used to include company logos etc in the plot.

AttributesX1 Required - X position in mm of the top left corner of

the graphic item.Y1 Required - Y position in mm of the top left corner of

the graphic item.X2 Required - X position in mm of the bottom right

corner of the graphic item.Y2 Required - Y position in mm of the bottom right

corner of the graphic item.

Data ValueA text string naming the graphic file to be included.

A.2.7 CaseData Element

DescriptionDefines items of case description data that will appear on the plot.


the area for output of the data item.Y1 Required - Y position in mm of the top left corner of

the area for output of the data item.X2 Required - X position in mm of the bottom right

corner of the area for output of the data item.Y2 Required - Y position in mm of the bottom right

corner of the area for output of the data item.Font Required - Integer denoting font to be used -


Size Required - Value defining data item text height as % of plot height

A-14


Style Optional - Text describing style of data value - BoldItalicBoldItalic

Data ValueA text string defining the data item to be output. Recognised values are.

TitleDataFileDescriptionLastModifiedAuthorRevisionCheckedByFSWVersion

A.2.8 Line Element

DescriptionDefines background lines to be drawn on the plot. Typically these are used to frame areas of the report.

AttributesX1 Required - X position in mm of the first end of the

line.Y1 Required - Y position in mm of the first end of the

line.X2 Required - X position in mm of the second end of the

line.Y2 Required - Y position in mm of the second end of the

line.LineWidth Required - Line width in pixels.

Data ValueNone

A-15


A.2.9 PlotArea Element

DescriptionDefines the area used to output the isopleth graph on the plot and sets the options used when drawing it.


the graph area.Y1 Required - Y position in mm of the top left corner of

the graph area.X2 Required - X position in mm of the bottom right

corner of the graph area.Y2 Required - Y position in mm of the bottom right

corner of the graph area.

Data ValueElements defining the options used to draw the isopleth graph as follows. Note one instance of each of these elements is required in the <PlotArea> data. None of these elements has any data value, all the required information is contained as attributes.

A.2.9.2 Grid Element

DescriptionDescribes how the background grid for the isopleth graph is to be drawn.

AttributesDisplay Required - defines whether grid is drawn. Allowed

values are Yes or No.Lines Required - defines number of grid lines within graph

on each axid. IntegerBackColour Required - defines colour of graph background.

Value can be Transparent or one of the colours from Table A.1 below.

A-16


A.2.9.3 Title Element

DescriptionDefines how the isopleth graph title will be output. The title is the name of the receptor grid that the isopleth applies to.

AttributesDisplay Required - defines whether title is included. Allowed

values are Yes or No.Space Required - Vertical spacing allowed for title as a

percentage of the Y range of the graph.Font Required - Integer denoting font to be used -


Table A.1, Allowed Colours

Yellow

Red

Green

Cyan

Orange

Lemon

PaleGreen

BlueGreen

PaleBlue

LightGrey

MidGrey

DarkGrey

White

Black

Other colours may be defined using a hex code to define the RGB contributions as follows0xRRGGBB where RR is red value, GG is green value and BB blue value in hex.For example 0xFF0000 is pure red.

A-17


Size Required - Value defining title text height as % of graph height.

Style Optional - Text describing style of title text - BoldItalicBoldItalic

A.2.9.4 Desc Element

DescriptionDefines how the graph description will be output. The description identifies whether the graph is a radiation, noise or temperature isopleth and the current units of measurement.

AttributesDisplay Required - defines whether description is included.

Allowed values are Yes or No.Space Required - Vertical spacing allowed for description

as a percentage of the Y range of the graph.Font Required - Integer denoting font to be used -


Size Required - Value defining description text height as % of graph height.

Style Optional - Text describing style of description text - BoldItalicBoldItalic

A.2.9.5 XAxis Element

DescriptionDefines how the isopleth X axis label will be output.

AttributesDisplay Required - defines whether X axis label is included.

Allowed values are Yes or No.

A-18


Space Required - Vertical spacing allowed for X axis label as a percentage of the Y range of the graph.

Font Required - Integer denoting font to be used - 0 = Arial1 = Courier2 = Times Roman

Size Required - Value defining title X axis label height as % of graph height.

Style Optional - Text describing style of X axis label text - BoldItalicBoldItalic

A.2.9.6 YAxis Element

DescriptionDefines how the isopleth Y axis label will be output.

AttributesDisplay Required - defines whether Y axis label is included.

Allowed values are Yes or No.Space Required - Horizontal spacing allowed for Y axis

label as a percentage of the X range of the graph.Font Required - Integer denoting font to be used -


Size Required - Value defining Y axis label height as % of graph height.

Style Optional - Text describing style of Y axis label text - BoldItalicBoldItalic

A.2.9.7 Scale Element

DescriptionDefines how the scale labels will be output.

A-19


AttributesFont Required - Integer denoting font to be used -


Size Required - Value defining scale label height as % of graph height.

A.2.9.8 Flare Element

DescriptionDefines how the stack, tip and flare will be drawn on the isopleth graph.

AttributesDisplay Required - defines whether the flare will be drawn.

Allowed values are Yes or No.FlameThick Required - defines thickness of line used to draw

flame in pixels.FlameColour Required - defines colour of line used to draw flame.

Allowed values are given in Table A.1.StackThick Required - defines thickness of line used to draw

stack in pixels.StackColour Required - defines colour of line used to draw stack.

Allowed values are given in Table A.1.TipThick Required - defines thickness of line used to draw tip

in pixels.TipColour Required - defines colour of line used to draw tip.

Allowed values are given in Table A.1.

A.2.10 LegendArea Element

DescriptionDefines the area used to output the legend for the isopleth graph on the plot and sets the options used when drawing it.

A-20



the legend data area.Y1 Required - Y position in mm of the top left corner of

the legend data area.X2 Required - X position in mm of the bottom right

corner of the legend data area.Y2 Required - Y position in mm of the bottom right

corner of the legend data area.

Data ValueElements defining the options used to draw the legend data on the isopleth graph as follows. Note one instance of each of these elements is required in the <LegendArea> data. None of these elements has any data value, all the required information is contained as attributes.

A.2.10.9 Layout Element

DescriptionThis defines the number of columns used to output the legend and the characteristics of the text part of the legend.

AttributesNumCols Required - Integer defining number of colums to be

used for drawing the legend.Font Required - Integer denoting font to be used for

legend label - 0 = Arial1 = Courier2 = Times Roman

Size Required - Value defining legend label height as % of legend data area height.

A-21


A.2.10.10 Desc Element

DescriptionDefines how the legend description will be output. The description identifies whether the graph is a radiation, noise or temperature isopleth as well as the units used.

AttributesDisplay Required - defines whether description is included.

Allowed values are Yes or No.Font Required - Integer denoting font to be used -


Size Required - Value defining description text height as % of legend data area height.

Style Optional - Text describing style of description text - BoldItalicBoldItalic

A.2.11 ContourSet Element

DescriptionDefines the details of the contours to be output on the isopleth graph.

AttributesUseLayout Required - Specifies whether the contour data from

the layout file is to be used. Allowed values Yes or No. If set to Yes the contour data will be taken from the layout file. If not, the contour data will be taken from the current isopleth definition for the receptor grid.

Data ValueMultiple elements defining the individual contour lines to be output. Up to 10 instances of <RadiationContour>, <NoiseContour> and <TemperatureContour> can be specified.

A-22


A.2.11.11 RadiationContour Element

DescriptionDefines the details of a single radiation contour to be output on the isopleth graph.

AttributesIsoValue Required - Specifies the radiation value of the

isopleth contour in internal program units of W/m2.Colour Required - Specifies the colour used to draw the

contour. Allowed values are given in Table A.1.LineWidth Required - Integer specifying the width of the line

used to draw the contour in pixels.Style Required - Specifies the style of the line used to draw

the contour. Allow values are.SolidDashedDottedDashDotDashDotDot

A.2.11.12 NoiseContour Element

DescriptionDefines the details of a single noise contour to be output on the isopleth graph.

AttributesIsoValue Required - Specifies the noise value of the isopleth

contour in internal program units of dB.Colour Required - Specifies the colour used to draw the



the contour. Allow values are.SolidDashedDotted

A-23


DashDotDashDotDot

A.2.11.13 TemperatureContour Element

DescriptionDefines the details of a single temperature contour to be output on the isopleth graph.

AttributesIsoValue Required - Specifies the temperature value of the

isopleth contour in internal program units of K.Colour Required - Specifies the colour used to draw the



the contour. Allow values are.SolidDashedDottedDashDotDashDotDot

A-24