UniSim Flare Reference Guide

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UniSim Flare

Reference Guide


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Copyright

April 2010 R390.1 Release

The information in this help file is subject to change over time. Honeywell may makechanges to the requirements described. Future revisions will incorporate changes,

including corrections of typographical errors and technical inaccuracies.

For further information please contact

Honeywell300-250 York StreetLondon, OntarioN6A 6K2Telephone: (519) 679-6570Facsimile: (519) 679-3977

Copyright Honeywell 2010. All rights reserved.

Prepared in Canada.


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1

Table of Contents

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

1.1 Introduction .................................................... 1-2

2 Interface ..............................................................2-1

2.1 Overview ........................................................ 2-2

2.2 Terminology .................................................... 2-2

2.3 Menu Bar ........................................................ 2-3

2.4 Toolbar ........................................................... 2-3

2.5 Status Bar....................................................... 2-52.6 Editing Data View............................................. 2-6

2.7 Setting Preferences .......................................... 2-8

2.8 Windows Menu............................................... 2-15

2.9 Help Menu..................................................... 2-16

3 Creating and Saving Cases ...................................3-1

3.1 Creating a New Case ........................................ 3-2

3.2 Opening an Existing Case.................................. 3-3

3.3 Saving a Case.................................................. 3-4

4 Components .........................................................4-1

4.1 Overview ........................................................ 4-2

4.2 Selecting Components ...................................... 4-2

4.3 Adding/Editing Components............................... 4-4

4.4 Binary Interaction Parameters.......................... 4-10

5 Scenarios..............................................................5-1

5.1 Overview ........................................................ 5-2

5.2 Scenario Manager ............................................ 5-2

5.3 Adding/Editing Scenarios................................... 5-3

5.4 Scenario Tools ................................................. 5-8

6 Pipe Network........................................................6-1

6.1 Pipe Manager................................................... 6-2

6.2 Ignoring/Restoring Pipes ................................... 6-2

7 Nodes ...................................................................7-1

7.1 Node Manager ................................................. 7-2


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7.2 Ignoring/Restoring Nodes.................................. 7-2

7.3 Connection Nodes ............................................ 7-3

7.4 Boundary Nodes............................................. 7-28

8 Calculations..........................................................8-1

8.1 Calculations Options ......................................... 8-2

8.2 Efficient Modeling Techniques .......................... 8-16

9 Databases.............................................................9-1

9.1 Overview ........................................................ 9-2

9.2 Database Features ........................................... 9-2

9.3 Setting the Password ........................................ 9-4

9.4 Pipe Schedule Database Editor ........................... 9-5

9.5 Fittings Database Editor .................................... 9-6

9.6 Component Database Editor .............................. 9-7

10 Viewing Data and Results...................................10-1

10.1 Overview ...................................................... 10-2

10.2 Components Data........................................... 10-2

10.3 Scenarios Data .............................................. 10-2

10.4 Pipes Data..................................................... 10-3

10.5 Sources Data................................................. 10-4

10.6 Nodes Data ................................................... 10-4

10.7 Messages ...................................................... 10-5

10.8 Pressure/Flow Summary.................................. 10-8

10.9 Compositions................................................. 10-8

10.10Physical Properties ......................................... 10-9

10.11Profile..........................................................10-11

10.12Flow Map .....................................................10-12

10.13Scenario Summary........................................10-13

10.14Graph Control...............................................10-14

10.15Trace Window...............................................10-25

11 PFD.....................................................................11-1

11.1 Overview ...................................................... 11-2

11.2 Object Inspection ........................................... 11-3

11.3 PFD Toolbar................................................... 11-3

11.4 Installing Objects ........................................... 11-8

11.5 Connecting Objects ........................................ 11-9

11.6 Manipulating the PFD...................................... 11-9

11.7 Printing and Saving the PFD Image..................11-11

11.8 Changing the PFD View Options.......................11-12


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12 Printing, Importing and Exporting......................12-1

12.1 Overview ...................................................... 12-2

12.2 Printing......................................................... 12-2

12.3 Import Wizard ............................................... 12-6

12.4 Importing Source Data...................................12-15

12.5 Export Wizard...............................................12-1912.6 Export Data Layouts ......................................12-19

12.7 Import/Export Examples ................................12-28

13 Automation.........................................................13-1

13.1 Overview ...................................................... 13-2

13.2 Objects......................................................... 13-2

13.3 UniSim Flare Object Reference ........................13-15

13.4 Example Automation In Visual Basic..............13-38

A Theoretical Basis ..................................................A-1

A.1 Pressure Drop..................................................A-2

A.2 Vapor-Liquid Equilibrium ................................. A-23

A.3 Physical Properties ......................................... A-27

A.4 Noise............................................................ A-35

B References ...........................................................B-1

C File Format ...........................................................C-1

C.1 Import/Export Details .......................................C-2

C.2 FMT Files Format............................................ C-31

D Glossary of Terms.................................................D-1

Index....................................................................E-1


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Introduction 1-1

1-1

1 Introduction

1.1 Introduction .................................................................................. 2

1.1.1 Related Documentation............................................................. 2


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1-2 Introduction

1-2

1.1 IntroductionThe guide provides a detailed description of all the features andfunctionality within UniSim Flare intended for process and processsystems engineers.

1.1.1 Related Documentation

Title Content

UniSim Flare GettingStarted Guide

Tutorials covering the basic use of UniSimFlare


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Interface 2-1

2-1

2 Interface

2.1 Overview ....................................................................................... 2

2.2 Terminology .................................................................................. 2

2.3 Menu Bar ....................................................................................... 3

2.4 Toolbar .......................................................................................... 3

2.5 Status Bar...................................................................................... 5

2.6 Editing Data View .......................................................................... 6

2.6.1 Changing Column Width............................................................ 6

2.6.2 Changing Column Order............................................................ 6

2.7 Setting Preferences ....................................................................... 8

2.7.1 General Tab............................................................................. 9

2.7.2 Defaults Tab ...........................................................................10

2.7.3 Databases Tab ........................................................................11

2.7.4 Reports Tab............................................................................12

2.7.5 PFD Tab .................................................................................13

2.7.6 Formatting Tab .......................................................................14

2.7.7 Import/Export Tab...................................................................14

2.8 Windows Menu .............................................................................15

2.9 Help Menu.....................................................................................16


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2-2 Overview

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2.1 OverviewUniSim Flare is designed to give you a great deal of flexibility in the wayin which you enter, modify and view the data and results whichcomprise your model of a flare system. This chapter describes thevarious components of the UniSim Flare interface. If you need help withany particular task, the on-line help can give you step-by-stepinstructions.

2.2 TerminologyThe terminology used to describe these components throughout thisguide is given in the following table.

Term Definitiona

Button Most views contain buttons. They perform a specific actionwhen selected (either by clicking the left mouse button orvia the appropriate hot key combination).

Icon Icons are like buttons, they perform a specific action whenselected (by clicking the left mouse button).

Checkbox Data items or settings that have an On/Off status areindicated by checkboxes. Selecting the checkbox will turn iton, selecting it again will turn it off.

Data View A window that contains a non-editable view of the modeldata and/or the calculation results.

View A modal window which allows you to enter the model data.

You cannot access any other element in the model until thisform has been closed.

Drop-down List A drop-down list is indicated by a down arrow next to afield. If you click on this arrow, a list of available options forthat field will be displayed.

Input Field Data items that are alphanumeric in nature are entered intoan input field. In general, the data that is entered in a fieldis checked for validity before you can continue.

Menu Bar The Menu Bar displays all of the program functions, whichcan be accessed by clicking on the appropriate menu item.This is described in more detail later in the chapter.

Modal/Non-ModalView

When a view is modal, you cannot access any otherelement in the simulation until you close it. Non-modalviews do not restrict you in this manner. You can leave anon-modal view open and interact with any other view ormenu item.

Scenario Selector This drop-down list shows the current scenario selected forthe case. On clicking the down arrow, located beside thefield, a list of all the scenarios will be displayed.

Calculation ModeSelector

This drop-down list shows the current calculation modeselected. Clicking the down arrow allows you to choosefrom Rating, Design or Debottleneck calculations.

Scroll Bar Whenever the information associated with a view or listexceeds what can be displayed, you may move through theview or list by using the scroll bar.


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Interface 2-3

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2.3 Menu BarThe menu bar allows access to all the program functions via menus andsub-menus.

The menu bar contains commands for each of the main areas ofprogram functionality:

As an alternative to using the mouse to click on the menu item, you canhit the alt key, then the underlined letter key. For example, to import

source data from the process simulator you would hit the alt key, andthen while holding down the alt, press the f, i and h keys in sequence(abbreviated as alt f i h).

2.4 ToolbarThe Toolbar contains a set of controls which give short-cut access to

Scroll Button Part of the Scroll Bar, allowing you to slide the list up ordown, or left or right.

Status Bar This displays the current model status. For moreinformation, see Status Bar.

Title Bar Indicates the UniSim Flare file currently loaded.

Toolbar The Toolbar contains a number of controls (icons/buttons)which give short-cut access to the most commonly usedprogram functions. This is described in more detail later inthis chapter.

Tool Tip Whenever you pass the mouse pointer over one of theicons/buttons on the toolbar, a Tool Tip will be displayed. Itwill contain a summary description of the action that willtake place if you click on that icon/button.

Menu Description

File Work with files (New, Open, Save), supply CaseDescription, import/export files, print, adjust printer setup,and set preferences. Also a list of previously opened casesis displayed at the bottom of the menu.

Build Access the Managers for Components, Scenarios, Pipes andNodes.

Tools Access various UniSim Flare utilities.

Calculations Set calculation options and start calculations.

Database Manages the pipe schedule, pipe fittings, and purecomponent databases and allows you to set a password.

View Look at summaries of the Data, the Results, and theProcess Flow Diagram (PFD).

Windows Arrange the display of windows (Cascade, Tile, etc.)

Help Access on-line help and program version information.

Term Definitiona


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2-4 Toolbar

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some of the program functions without the need to navigate through aseries of menus and/or sub-menus.

Name Icon DescriptionNew Case Starts a new case.

Open Case Opens a case that has been previously saved todisk.

Save Case Saves a case to disk using the current file name. If you want to save the case with a different filename, use the Save As command in the File menu.

Print Data and Results Opens a Print view, which allows you to print theentries from the Database, Data and Resultsgroups. You can either print to a printer or to afile.

Display Metric Units Displays data and results in Metric units.

Display Imperial Units Displays data and results in Imperial units.

Display PFD Displays the Process Flow Diagram.

Display Pipe Data View Displays the Pipe data view.

Display Source DataView

Displays the Source data view.

Display Node Data View Displays the Node data view.

Open Pressure/FlowSummary View

Displays the Pressure/Flow Summary view.

Open Profile GraphicalView

Displays the graphical Profile view.

Start Calculations Starts the UniSim Flare calculations.

Stop Calculations Stops the UniSim Flare calculations.


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Interface 2-5

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There are also two drop-down lists in the toolbar:

2.5 Status Bar

The status bar displays the current status of the model. There are twogeneral regions in the status bar:

The calculation time can be reduced by hiding the status bar, which isparticularly useful for large cases.

The first region displays the program status - IfEdit isdisplayed, you can make changes to your model. Aftercalculations, this field will display Done.

Name Description

Calculation ModeSelector This drop-down list selects and displays the current calculationmode.

The options are:Rating - It is used to check the existing flare system in a plant.This method calculates the pressure profile for the existing pipenetwork.Design - It is used to design a new flare system for the plant.During calculation it adjusts the diameters of all pipes until allthe design constraints of MABP velocity, etc. have been met.These diameters can be smaller than the initially defined data.Debottleneck - It is used to determine which areas of the flaresystem must be increased in size due to either the uprating ofthe existing plant and hence flare loading, or the tie-in of newplant. This mode can only increase pipe diameters from theircurrent size, it cannot reduce them.

Scenario Selector This drop-down list show the current scenario selected for thecase. On clicking the down arrow, located beside the field, a listof all the scenarios will be displayed.

Note: The Toolbar can be hidden by unchecking the ShowToolbar in the Preferences view.

Figure 2.1


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2-6 Editing Data View

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The second region displays important information duringcalculations, such as the iteration error and the current pipebeing solved.

2.6 Editing Data ViewYou can change the position and width of some of the columns in eachof the data views such as the Pressure/Flow Summary view.

2.6.1 Changing Column Width1. To change the width of a column, move the mouse pointer until it is

over the vertical column separator line to the right of the columnthat you want to resize (e.g. Flowrate). The mouse pointer willchange to a double-headed arrow.

2. Click and hold down the primary mouse button, then drag theseparator line to the new position.

3. The column width set here remains in effect for the duration of thecurrent session and is saved when you exit UniSim Flare.

2.6.2 Changing Column Order1. To reposition columns, first select the columns by positioning the

mouse pointer in the column heading(s) (you will see a down

Note: The Status Bar can be hidden by unchecking the ShowStatus Bar checkbox in the Preferences view.

Figure 2.2


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Interface 2-7

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arrow), then clicking. The column heading will now be shaded.

2. Now click anywhere in the shaded region and hold down theprimary mouse button. The move column cursor will be shown, and

there will be its now two colored arrows either side of the headerwhich contains the cursor. While holding down the mouse button,drag the column(s) to their new position. The two colored arrowseither side of the header will move as you drag the column(s) andindicate where the selected column(s) will be transferred. In thiscase, the Mass Flowrate and the Molar Flowrate columns will bepositioned between the Noise and the Source Back Pressurecolumns.

3. Release the mouse button. The selected column(s) will remain intheir new location within the data view.

Figure 2.3

Figure 2.4

Note: You can highlight multiple columns by clicking and

dragging the mouse over the adjacent columns you want toselect. Alternatively, you could hold the SHIFT key and clickon the additional adjacent columns you want to select.


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2-8 Setting Preferences

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4. The change in column order remains in effect for the duration of thecurrent session and is saved when you exit UniSim Flare.

2.7 Setting PreferencesThe Preferences view allows you to specify default information for thesimulation case.

1. To access the Preferences view, select Preferences from the Filemenu (alt f p). The Preferences view will be displayed.The information on the Preferences view is divided into differenttabs:

General, Defaults, Databases, Reports, Import/Export andPFD tab.

Figure 2.5


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Interface 2-9

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2.7.1 General Tab

The following fields are available on this tab:

Figure 2.6

Options Description

Show Status Bar Select this checkbox to display the Status bar.Unchecking this option to hide the Status Bar canspeed up calculations in large cases.

Show Tool Bar Activate this checkbox to display the Tool bar.

Timed Backup Select this checkbox to activate a periodically backupof the current case. File is saved back to the directoryas Backup.ufnw.

Backup Frequency This field is only accessed if the Timed Backupcheckbox is selected. The default value is 10 minutes.

Compress Files If checked, the data files will be saved in a compressedformat that can reduce the file size of the saved casesby a factor of up to 50.

Edit Objects On Add On activating this checkbox, the editor view will bedisplayed as the nodes/pipes are added to the PFD.

Units Specify the units set to be used for the simulation. Theavailable unit sets are Metric and British.

Work Directory Specify the directory for temporary files, which shouldbe writeable.

Auto Flash Source Nodes Activate the Auto Flash Source Nodes checkbox toautomatically flash the source fluid when it is edited.Otherwise sources are flashed during the calculation.

Display Total Pressure Select this checkbox to display the total pressure,which is a sum of the static pressure and the velocitypressure, instead of the static pressure.


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2-10

2.7.2 Defaults TabThe default data values given on the Default tab applies only to newinstances of pipe class of pipes and nodes. The value for each instancemay be freely edited at any stage.

Display VelocityProperties Used By

Pressure DropCalculation

Select this checkbox to display properties that arevelocity dependant based upon the velocities derived

from rated flow rather than from the nominal flow.

Save Phase Properties Phase properties can be saved by activating thischeckbox. The disk space/memory requirements aresignificantly effected by this option, especially for largecases. It is advised to select this option only if youhave a high specification PC.

Hide Results ForUncalculated Pipes

Selecting this option will hide the results for pipes thathave not been calculated in the last run of the model.This prevents cluttering of the results view withuncalculated values from sections of the flare networkthat might have been ignored.

Trace Buffer Size This field specifies the size in bytes of the text bufferdisplayed by the Trace window. Larger values will allowmore text to be stored. The default value of 32000 isadequate for most cases.

Figure 2.7

Options Description


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Interface 2-11

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The options available on this tab are:

CS = Carbon Steel

SS = Stainless Steel

2.7.3 Databases TabThe databases for the Components, Pipe Schedules and Pipe

Fittings can be specified here.

Options Description

Composition Basis Select composition basis for each of the relief sources:Molecular Weight - The molecular weight of the fluidis given. Mole fractions are estimated by UniSim Flare,based upon the list of installed components.Mole/Mass Fractions - A full component-by-component composition must be given for the fluid.

Tee Type Select the tee type to be set as a default for all the tees inthe model. The available tee types are 90o, 60o, 45o and30o tee.

Pipe Material This is the default material to be used in new pipes. Thetwo materials available for selection are Carbon Steel andStainless Steel.

Use Pipe Class Activate this checkbox to use the pipe class to restrict theavailable uses for pipes.

CS/SS Roughness Set the material roughness to be used in calculation. Thedefault CS Roughness is 0.04572 mm and SS Roughness is0.02540 mm.

Figure 2.8


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2-12

If the Save Database Directories With Model checkbox is checkedthen these locations are stored with the model. This is useful if thedatabases have been modified for use with specific models.

2.7.4 Reports TabYou can specify the directories in which to save the report definition foreach of the entries in the Report list.

If the Save Report Format Paths With Model check box in checkedthen these locations are stored with the model. This is useful if thereport formats have been modified for use with specific models.

Figure 2.9


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Interface 2-13

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2.7.5 PFD Tab


Figure 2.10

Option Description

Use Wire FrameIcons

When selected, pipe and node icons in the PFD are drawnas wireframe outlines rather than shaded pictures.Selecting this option can speed the drawing of the PFD forlarge models. If the PFD is already open it must be closedand reopened to see the change.

Font Name Allows selection of the font to be used for pipe and nodelabels in the PFD.

Font Size Allows definition of the size of the font used for pipe andnode labels in the PFD.

2.5 x Scale factor The factor to be used by UniSim Flare to scale the PFDwhen importing models created in earlier versions ofUniSim Flare.


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2.7.6 Formatting Tab


2.7.7 Import/Export TabYou can specify the name and location of the Import and Exportdefinition files to be used when transferring information betweenUniSim Flare and Access, Excel or XML files. Entries allow specificationof the default definition files and the base definition files to be used for

Figure 2.11

Option Description

Data Formatting Group

Display Using

Significant Figures

Activate this check box to display all results to a number of

significant figures rather than to a fixed number of decimalplaces.

Sig. Figures The number of significant figures used for the display ofresults.

Printing Group

Use Header Activate this check box to add a header at the top of eachprinted page.

Use Footer Activate this check box to add a footer at the Bottom of each printed page.

Binding margin A margin of this size is placed along the long side ofprintouts to allow for binding.

Tiled Scale Factor For tiled printouts of the PFD view, the diagram will bescaled by this factor. Larger values will tile the printout overmore pages.


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Interface 2-15

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creating new customized import export definition files.

If the Save Import/Export Paths With Model check box in checkedthen these locations are stored with the model. This is useful if thedefinition files have been modified for use with specific models.

2.8 Windows MenuThis is a general Windows application function. The options are:

Figure 2.12

Option Description

Cascade Cascade all currently-open windows.

Tile Horizontally Tile all currently-open windows horizontally.

Tile Vertically Tile all currently-open windows vertically.

Arrange Icons Organize icons at the bottom of the screen.

Open All Open all the windows, which can be accessed through theView menu bar

Close All Close all windows.


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2-16 Help Menu

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2.9 Help MenuThe options under the Help menu are:

Option Description

Contents Displays the UniSim Flare Help contents.

Using Help Displays the UniSim Flare Help contents.

Support Opens the Honeywell web page.

About Honeywell UniSimFlare...

Displays UniSim Flare software version.


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Creating and Saving Cases 3-1

3-1

3 Creating and Saving

Cases3.1 Creating a New Case...................................................................... 2

3.2 Opening an Existing Case............................................................... 3

3.3 Saving a Case ................................................................................ 4


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3-2 Creating a New Case

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3.1 Creating a New CaseWhen you start UniSim Flare, a new case is automatically created.

When you start UniSim Flare, the Desktop area will be blank. Beforeyou can work, you must either create a new case, or retrieve a savedcase.

1. To start a new case, do one of the following: Select New from the File menu in the menu bar. Use the hot key combination alt f n. Click on the New Case icon in the toolbar.

The Case Description view will be displayed.

Enter appropriate data into the User Name, Job Code, Project, andDescription fields and then click the OK button.

Figure 3.1

Note: The case description can be modified later by selectingDescription from the File menu.


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Creating and Saving Cases 3-3

3-3

2. After you enter the case description information, the ComponentManager view appears as shown in the figure below:

3. Select the desired components as described in Components andclick OK. You can now set up the simulation.

3.2 Opening an Existing CaseWhen you open a case that has previously been stored on disk, all datafrom the current case is cleared; however, the arrangement of anywindows that are already open is maintained.

1. To open an existing case, do one of the following: Select Open from the File menu. Use the hot key combination alt f o. Click the Open Case icon on the toolbar.

2. The File Open view appears.

3. Select the file to be opened by doing one of the following:

Type the filename (including exact directory path if necessary)into the Filename field and click the OK button.

Search the directory using the Look in drop-down menu andupon finding the file, click once on the file name to highlight itand then click the OK button.

Search the directory using the Look in drop-down menu andupon finding the file, double click the file name.

4. It is also possible to open a recently used file by selecting it fromthe list at the bottom of the File menu.

Figure 3.2


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3-4 Saving a Case

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3.3 Saving a CaseCases may either be saved using the current case name or under a newname.

1. To save a case using the current file name, do one of the following: Select Save from the File menu. Use the hot key combination alt f s. Click on the Save Case icon on the toolbar.

2. To save a case using a new name, do one of the following:

Select Save As from the File menu. Use the hot key combination alt f a.

3. When you're saving the case for the first time or with a new name,the Save UniSim Flare Model view will appears.

4. Select the file to be saved by directly entering it, or selecting theappropriate file from the list in the view which contains all the filesand folders. The Save in drop-down list can be used to change thedirectory and/or drive.

5. Clear the Filename field, type in the file name you want to give tothe case in and click on the OK button.

You will be asked to confirm that you want to overwrite if an existing file

is named.

Note: You do not have to include the .ufnw extension. UniSimFlare will add it on automatically.


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Components 4-1

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4 Components

4.1 Overview ....................................................................................... 2

4.2 Selecting Components ................................................................... 2

4.2.1 Component Types .................................................................... 2

4.2.2 Component List ....................................................................... 3

4.2.3 Matching the Name String......................................................... 3

4.2.4 Removing Selected Components ................................................ 4

4.3 Adding/Editing Components.......................................................... 4

4.3.1 Add Hypothetical Component/Edit Component View...................... 5

4.3.2 Identification Tab ..................................................................... 5

4.3.3 Editing Database Components ................................................... 7

4.3.4 Estimating Unknown Properties.................................................. 8

4.3.5 Organizing the Component List .................................................. 9

4.3.6 Move Single Component............................................................ 9

4.3.7 Swapping two components ........................................................ 9

4.3.8 Changing the Components ........................................................ 9

4.3.9 Combining Components ...........................................................10

4.4 Binary Interaction Parameters .....................................................10


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4-2 Overview

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4.1 OverviewData for all components that will be used in the simulation must beselected before the sources are defined. These components may betaken from the standard component library, or you may define yourown components, known as hypothetical components.

You may select components from the Component Manager, which canbe accessed by selecting Components from the Build menu.

The Component Manager view will be displayed:

This view displays all of the Database and Selected components, andprovides various tools which you can use to add and edit database andhypothetical components.

4.2 Selecting Components

4.2.1 Component TypesYou may filter the list of available components to include only thosebelonging to a specific family. The All and None buttons turn all of thefilters on and off, respectively, while the Invert button toggles thestatus of each checkbox individually. As an example, if only theHydrocarbons (HC) and Misc options were on, and you pressed the

Figure 4.1


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Components 4-3

4-3

Invert button, then these two options would be turned off, and theremaining options would be turned on.

4.2.2 Component ListComponents can be chosen from the Database list, and added to theSelected group, using one of the following methods:

Arrow Keys - use the arrow keys to move the highlight up ordown one component.

PageUp/PageDown - Use these keyboard keys to advance anentire page forward or backward.

Home/End - The key moves to the start of the listand the key moves to the end of the list.

Scroll Bar - With the mouse, use the scroll bar to move up anddown through the list.

You can highlight multiple components to add to the Selected list usingthe normal windows shift-click and ctrl-click options in the Databaselist.

Enter a character - When you type a letter or number, you willmove to the next component in the list which starts with thatcharacter. If you repeatedly enter the same character, you willcycle through all of the components which start with thatcharacter.

To add a component, you must first highlight it (by moving through thelist until that component is highlighted), then transfer it by double-clicking on it or clicking the Add button.

4.2.3 Matching the Name StringThe interpretation of your input is limited to the Component Typeswhich are checked.

Another way to add components is through the Selection Filter

feature. The Selection Filter cell accepts keyboard input, and is usedto locate the component(s) in the current list that best matches yourinput.

You may use wildcard characters as follows:

? - Represents a single character. * - Represents a group of characters of undefined length. Any filter string has an implied '*' character at the end.

Note: You can select multiple components by using theSHIFT or CTRL keys as you select components.


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4-4 Adding/Editing Components

4-4

Some examples are shown here:

As you are typing into the Selection Filter cell, the component list is

updated, matching what you have presently typed. You may not have toenter the complete name or formula before it appears in the componentlist.

4.2.4 Removing SelectedComponents

You can remove any component from the Selected Component list:

You can select multiple components using shift-click and ctrl-clickoptions.

1. Highlight the component(s) you want to delete.2. Click either the Delete button on the Component Manager view, or

press the delete key.

Once the component(s) are removed from the list, any sourcecompositions that used this component will be normalized.

4.3 Adding/EditingComponents

To create a new component (hypothetical), click the Hypotheticalbutton. Hypothetical components are set up in the same manner asdatabase components. Previously defined hypothetical components canbe changed by selecting them in the Selected Component list and

then clicking the Edit button.

Filter Result

methan methanol, methane, etc.

*anol methanol, ethanol, propanol, etc.

?-propanol 1-propanol, 2-propanol

*ane methane, ethane, propane, i-butane, etc.


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4.3.1 Add Hypothetical

Component/Edit ComponentViewUpon clicking either the Hypothetical button or the Edit button theComponent Editor view opens up.

4.3.2 Identification TabThe minimum data requirements for creating a component are specifiedhere:

Component Types:

Hydrocarbon Miscellaneous Amine Alcohol Ketone Aldehyde

Ester Carboxylic Acid Halogen Nitrile Phenol Ether

Figure 4.2


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4-6


Critical TabCritical properties are specified here.


Input Field Description

Name An alphanumeric name for the component (e.g. - Hypo -1). Up to 15characters are accepted.

Type The type of component (or family) can be selected from the drop-down menu provided. There is a wide selection of families to choosefrom, which allows better estimation methods to be chosen for thatcomponent.

ID The ID number is provided automatically for new components andcannot be edited.

Mol. Wt. The molecular weight of the component. Valid values are between 2and 500.

NBP The normal boiling point of the component.

Std. Density The density of the component as liquid at 1 atm and 60 F.

Watson K The Watson characterization factor.

Figure 4.3


Critical Pressure The critical pressure of the component. If the component

represents more than a single real component, the pseudocritical pressure should be used. Valid values are between0.01 bar abs and 500 bar abs.

Critical Temp. The critical temperature of the component. If thecomponent represents more than a single real component,the pseudo critical temperature should be used. Validvalues are between 5 K and 1500 K.

Critical Volume The critical volume of the component. If the componentrepresents more than a single real component, the pseudocritical volume should be used. Valid values are between0.001 m3/kg and 10 m3/kg.


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Other TabCoefficients for the polynomial equations for the prediction of Ideal Gasthermodynamic properties and parameters for the viscosity calculationsare specified here:


4.3.3 Editing Database

ComponentsIf you want to change the data for one of the database components,e.g. Methane, you will find that opening the Component Edit view for

Acentric Factor The acentric factor of the component. Valid values arebetween -1 and 10.

Acentric Factor (SRK) The Soave-Redlich-Kwong acentric factor of the component(also called the COSTALD Acentricity).

Figure 4.4


Hi A, Hi B, Hi C, Hi D, Hi E, and Hi F The coefficients for the ideal gas specificenthalpy equation:

Entropy Coef. The coefficient for the entropy equation.

Viscosity A and Viscosity B Viscosity coefficients used in the NBS Method(Ely and Hanley, 1983).


Hi

A BT CT2 DT 3 ET 4 FT5+ + + + +=


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this component will display read only values that cannot be changed.

In order to update the data for a database component it must first bechanged to a hypothetical component.

At the very minimum, you need to specify the Molecular Weight.However, it is a good practice to specify at least two of the followingproperties:

Molecular Weight Normal Boiling Point Standard Density

This is done by clicking the Hypothetical button on the Component

Editor view. UniSim Flare will convert the displayed databasecomponent to a hypothetical as indicated by the adding of a * characterto the name and by changing the component ID to -1. The data valuescan then be updated.

4.3.4 Estimating UnknownProperties

If any of the above data is unknown, then click Estimate to fill-in theunknown properties.

Supply as many properties as are known, so that the estimation can beas accurate as possible.

Figure 4.5


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4.3.5 Organizing the Component

ListThe Selected Components list can be organized in the followingdifferent ways.

Sorting the Component List

The Sort button allows the whole component list to be sorted by thecriteria selected from the following pop up list:

4.3.6 Move Single ComponentA single component may be moved up and down the list by clicking onit in the list of selected components and then clicking either the up or

down arrow buttons.

4.3.7 Swapping two componentsIn the Component Manager view, select the first component in theSelected Component list by clicking on it. Then select the secondcomponent either using the SHIFT key if the two are in sequence orpressing the ctrl key and then clicking on the component. Swap thetwo components by clicking the Swap button.

4.3.8 Changing the ComponentsYou can switch the components in the Selected Component list withthe ones in the Database list while maintaining the source molefractions.

In the Component Manager view, select the components in both theSelected Components and the Database lists. Click the Change

Sorting Option Description

Name Arranged components alphabetically in descending order.Molecular Weight Components are listed according to increasing molecular

weight.

Normal Boiling Point(NBP)

Select this to arrange components in increasing NBP value.

Group Group the components by type.


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button to switch the two components.

4.3.9 Combining ComponentsMultiple components can be combined and represented by a singlecomponent to reduce the number of components in the model.

This is done by selecting the components you want to combine bycontrol-clicking them in the Selected Components list and thenclicking the Combine button. A pop-up view will then ask you to selectwhich of these combined components should be used as the targetcomponent to combine your selected components into. Once the targetcomponent has been selected the combined components will updateeach source in the model by summing the composition of all of the

combined components and assigning it to the target component.

Reducing the number of components in this way is useful since it cangreatly speed the calculations. This is especially true where a modelcontains sources defined with a long list of hypothetical components.

For example consider a model containing the hypothetical componentsBP200, BP225, BP250, BP275, BP300 boiling at 200 C, 225 C, 250 C,275 C and 300 C respectively. Since these components are likely tostay in the liquid phase throughout the flare system, they may becombined into a single component, BP250 without significant loss ofaccuracy. As another example, in a purely gas phase flare system it is

possible to combine isomers such as i-Butane and n-Butane into asingle component n-Butane without compromising results.

4.4 Binary InteractionParameters

Binary Interaction Coefficients, often known as KIJ's are factors that areused in equations of state to better fit the interaction between pairs ofcomponents and hence improve the accuracy of VLE calculations.

UniSim Flare allows the user to specify binary interaction parametersfor the Peng Robinson and Soave Redlich Kwong VLE methods or toestimate them through the Binary Coeffs tab of the Component


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Manager view as shown here.

To define binary interaction coefficients first select either the PengRobinson or Soave Redlich Kwong VLE method using the drop-down listat the top of the view.

Individual binary interaction parameters are set by selecting therequired entry in the matrix and typing in the new value.

Individual binary interaction parameters may be estimated by selectingthe required entry in the matrix and clicking the Estimate button. Theestimation method is based on the components boiling point, standardliquid density and critical volume.

It is possible to set several binary interaction parameters at the sametime either by clicking the Select All button to select the whole matrixor by control-clicking the two corners of a rectangular area in thematrix. The selected entries can then be estimated by clicking the

Figure 4.6

Note: Binary interaction coefficients are not used by eitherthe Ideal Gas or Lee Kesler VLE methods at present. Theview will show the binary interaction coefficient matrix for

the selected VLE method.

Note: The matrix is symmetrical i.e. KJI is the same value asKJI and updating an entry will also update the correspondingentry in the table. E.g. updating the entry in the Methanecolumn, Propane row will also update the entry in thePropane column, Methane row.


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Estimate button or set to 0.0 by clicking the Zero HC-HC button.

The Reset All button causes all interaction parameters to be set to

their default values. Generally this is 0.0 for hydrocarbon componentswith non zero values being supplied only for common polarcomponents.

If the Auto Estimate check box is checked then the interactionparameters for new components are automatically estimated as theyare added to the model.


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Scenarios 5-1

5-1

5 Scenarios

5.1 Overview ....................................................................................... 2

5.2 Scenario Manager .......................................................................... 2

5.3 Adding/Editing Scenarios .............................................................. 3

5.3.1 General Tab............................................................................. 4

5.3.2 Constraints Tab........................................................................ 4

5.3.3 Sources Tab ............................................................................ 65.3.4 Estimates Tab.......................................................................... 6

5.4 Scenario Tools ............................................................................... 8

5.4.1 Adding Single Source Scenarios ................................................. 9


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5.1 OverviewA scenario defines a set of source conditions (flows, compositions,pressures and temperatures) for the entire network. The design of atypical flare header system will be comprised of many scenarios foreach of which the header system must have adequate hydrauliccapacity. Typical scenarios might correspond to:

Plantwide power failure. Plantwide cooling medium or instrument air failure. Localized control valve failure. Localized fire or Depressurization.

The scenario management features within UniSim Flare allow you tosimultaneously design and rate the header system for all of the possible

relief scenarios.

As well as having different source conditions, each scenario can haveunique design limitations that will be used either to size the pipes or to

highlight problems when an existing flare system is being rated. Forexample, a Mach number limit of 0.30 might be applied for normalflaring compared to a Mach number limit of 0.50 or greater at the peakflows encountered during plant blowdown.

5.2 Scenario ManagerScenarios can also be selected by selecting the scenario in the Scenarioselector on the tool bar.

Scenarios are managed via the Scenario Manager view. This view has

buttons that allow you to add, edit or delete scenarios as well as toselect the current scenario for which scenario specific data is displayed.All cases have at least one scenario.

1. To access the Scenario Manager view, select Scenarios from the

Note: Although the major relief scenarios will normallyconstrain the size of the main headers, care should be takenin the evaluation of velocities in the individual relief valvetailpipes and sub headers. When looking at relief valveswhich might operate alone, lower back pressures in the mainheaders may lead to localized high velocities andconsequently choked flow in the tail pipes.


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Build menu.

The Scenario Manager view will be displayed.

The Scenario Manager view displays all Scenarios in the case, andindicates the Current Scenario. Several buttons are available:

5.3 Adding/Editing ScenariosUniSim Flare has no pre-programmed limits on the number of scenarioswhich can be defined within a single case.

To add a scenario, click the Add button on the Scenario Manager view.If there is already a scenario present in the Scenario list, clicking theAdd button will show a Clone Scenario Form view. You can select anexisting scenario from the list to be used to initialize the flows,compositions, pressures and temperatures of all the sources in the newscenario.

Figure 5.1

Button Description

Add Adds a new scenario.

Edit Edits the highlighted scenario.

Delete Removes the currently highlighted scenario. There mustalways be at least one scenario in the case.

Sort Arrange the scenario list alphabetically in descending order.

Up and Down Arrow Move the highlighted scenario up and down the Scenariolist.

Swap Swap the two selected scenarios in the list.

Current To make a scenario the current one, highlight theappropriate scenario, and then click on the Current button.

OK Closes the Scenario Manager view.


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The Next button allows you to continue adding scenarios withoutreturning to the Scenario Manager.

To edit a scenario, highlight it, and then click the Edit button. Foradding and editing a scenario, the views are similar except for the Nextbutton on the Scenario Editor view for adding a scenario.

5.3.1 General TabYou may provide the following information on the General tab:

5.3.2 Constraints TabThis tab requires the following information for both headers and

Figure 5.2

Data Description

Name An alphanumeric description of the scenario (e.g. PowerFailure). Up to 40 characters are accepted.

System Back Pressure The system back pressure at the flare tip exit. This willnormally be atmospheric pressure, but can be set torepresent system design conditions at the exit point. If leftempty, the value on the Calculation Options Editor view willbe used. The minimum value is 0.01 bar abs.


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tailpipes.

Tailpipes are indicated by the Tailpipe field on the Connections tab ofthe Pipe Editor view. You may provide different design information(Mach Number, Noise at 1 m, Vapor Velocity, Liquid Velocity) for theHeaders and Tailpipes. Any field may be left empty, in which case theywill be ignored.

Figure 5.3

Data Description

MachNumber

The maximum allowable Mach number for all pipe segments.Calculated values that exceed this number will be highlighted in theresults.

VaporVelocity

The maximum allowable vapor velocity. Calculated velocities thatexceed this value will be indicated in the results.

LiquidVelocity

The maximum allowable liquid velocity. Calculated velocities thatexceed this value will be indicated in the results.

Rho V2 It is the density times the velocity square. This value is normallyused as a limiting factor to prevent erosion.

Noise The maximum allowable sound pressure level at a distance of 1meter for all pipe segments. This is an average value over the lengthof the pipe. Calculated values that exceed this specification will behighlighted in the results.

Note: Whilst rating the network you may define a Machnumber constraint of 1.00, in order to highlight only chokedflow conditions. This is not recommended for designcalculations where a more reasonable value such as 0.5 or0.7 will lead to a more rapid solution towards the maximumallowable back pressure constraints.


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5.3.3 Sources Tab

If a source is ignored, the MABP constraint is ignored by sizingcalculations.

When you select the Sources tab, you will see a view similar to the oneshown in Figure 5.4. All sources are displayed on this tab.

This tab is useful in that you can easily toggle whether or not individual

sources are to be included in the current scenario, without having toeither unnecessarily delete sources or set the flow of a source to zero.

5.3.4 Estimates TabThe Estimates tab allows some control over the selection andinitialization of flowrates for pipes which are to be used as tears in thesolution of looped systems. The use to which each field is put isdependant upon the Structural Analyser setting on the Solver tab ofthe Calculation Options Editor view.

The checkboxes in the No Tear column of the table allow you toprevent pipes from being used as tears - select the checkbox to preventa pipe from being used as a tear or clear it to allow it. This setting hasno effect if the Simultaneous structural analyser is used.

When the Convergent structural analyser is used, the Molar Flowcolumn recommends a tear location and initial value for the flow at thetear location. If the structural analyser does find that the pipe may be a

Figure 5.4


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Scenarios 5-7

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valid tear location then this value is ignored.

When the Simultaneous structural analyser is used, the Molar Flow

column is used to seed the analyser. This value will always impact theinitialization as long as the structural analysis succeeds but the pipe willnot necessarily be selected as a tear pipe. In the event that thestructural analysis fails with any Molar Flow estimates then the modelwill be initialized by the default values.

Since the Simultaneous structural analyser generally offers better

performance than the Convergent analyser it will rarely be necessaryto specify information on the Estimates tab other than for the purposeof improving the speed of convergence of the model. In the event thata model proves problematic to converge, a number of additionalcolumns are available to tune the convergence algorithms. These may

Figure 5.5


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5-8 Scenario Tools

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be exposed by stretching the view horizontally.

The Max. Step column defines the maximum change to the flow in atear pipe over a single iteration whilst the Max. Flow and Min. Flowcolumns constrain the flow in a tear pipe. Not all these values are usedby all the Loop Solver algorithms.

5.4 Scenario ToolsThe complete analysis of a flare system should ideally include analysisof the system for the scenarios in which each source relieves on itsown. For a large network with many sources, it can become tedious to

define each of these scenarios. These can automatically be added toyour model as follows.

Figure 5.6

Max. Step Max. Flow Min. Flow

Newton-Raphson 3 3 3

Brogden 3 3 3

Force Convergent

Levenberg-Marquardt 3 3

Conjugate Gradient Minimization

Quasi-Newton Minimization


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5.4.1 Adding Single Source

ScenariosSelect Add Single Source Scenarios from the Tools menu or use thehot key combination alt t n.

This will analyze your model and add a scenario for each source thathas a non-zero flow rate defined in at least one scenario. Source datawill be copied from the scenario in which it has the highest flow rate.


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6 Pipe Network

6.1 Pipe Manager................................................................................. 2

6.2 Ignoring/Restoring Pipes .............................................................. 2

6.2.1 Connections Tab....................................................................... 3

6.2.2 Dimensions Tab ....................................................................... 5

6.2.4 Heat Transfer Tab..................................................................... 8

6.2.5 Methods Tab...........................................................................10

6.2.6 Summary Tab.........................................................................13

6.2.7 Multiple Editing.......................................................................13

6.2.8 Pipe Class Editor .....................................................................14


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The pipe network comprises a series of interconnected pipes. Thesepipes can be added, edited and deleted from the Pipe Manager.

6.1 Pipe ManagerTo access the Pipe Manager, select Pipes from the Build menu.

The following buttons are available:

6.2 Ignoring/Restoring PipesWhen you ignore a single pipe, all upstream pipes are automaticallyignored.

You can ignore single or multiple pipes within the model. When youignore a single pipe, all upstream nodes are automatically ignored. This

Figure 6.1

Button Description

Add Adds a new pipe. This new pipe will be named with a numberdepending upon the number of pipes already added.

Edit Allows you to edit the currently highlighted pipe.

Delete Allows you to remove the currently highlighted pipe.

Sort Sort the pipes list alphabetically (in descending order) either byname or location.

Up andDown Arrow

Move the highlighted pipes up and down the list.

Swap Swap the two selected pipes in the list.

OK Closes the view.


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enables you to do what if type calculations, where part of the networkcan be excluded from the calculation without the need for deletion andreinstallation of the appropriate nodes.

To ignore a pipe:

1. Open the pipe editor view of the pipe that you want to ignore.2. On the Connections tab, activate the Ignore checkbox.

To restore a pipe that has previously been ignored:

1. Open the pipe editor view of the pipe that you want to restore.2. On the Connections tab, deactivate the Ignore checkbox.

6.2.1 Connections TabThe name of the pipe segment and connectivity information is specified

Figure 6.2


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6-4 Ignoring/Restoring Pipes

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here.


You have the option of modeling a pipe segment as a main header or atailpipe. The ability to classify a pipe as either a tailpipe or a header

Figure 6.3

Input Data Description

Name An alphanumeric description of the pipe segment. Up to 30characters are accepted.

Location An alphanumeric description of the location within the plant for thesegment. This is a useful parameter for grouping pipes together viathe Sort command.

UpstreamNode

This is the name of the node upstream of the pipe. The drop-downlist allows you to select from a list of existing unconnected nodes inthe model. Alternatively the name of a new node can be entered. Ifthis is done you will be asked to specify the type of node through apop-up list when you move to the next entry.

DownstreamNode

This is the name of the node upstream of the pipe. The drop-downlist allows you to select from a list of existing unconnected nodes inthe model. Alternatively the name of a new node can be entered. Ifthis is done you will be asked to specify the type of node through apop-up list when you move to the next entry.

Tailpipe This drop-down list allows you to select whether the pipe should betreated as a tailpipe. If set to Yes and the Rated Flow for Tailpipes

calculation option is selected in the Calculation Options view, thepressure drop for this pipe will be calculated using the rated flow inplace of the relieving flow rate.

Ignore This checkbox may be selected to remove the pipe from calculationstemporarily. When selected the pipe and all upstream nodes andpipes will be ignored during calculations.


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allows us to perform calculations in which the pressure drop fortailpipes is determined by the rated flow and that for headers isdetermined by the nominal flow. This is in accordance with API-RP-521.

In the Scenario Editor view, you can set design limits for the MachNumber, Vapor and Liquid Velocities, Rho V2 and Noise separately forthe main headers and the tailpipes.

6.2.2 Dimensions TabThe physical dimensions and characteristics of the pipe segment arespecified here.


Figure 6.4


Length The physical length of the pipe segment. This length is used in

association with the fittings loss coefficients to calculate theequivalent length of the pipe. If you have equivalent length datafor your network, enter this data here as the sum of the actuallength plus the equivalent length of the fittings and enter zerofor the fittings loss coefficients.

Elevation Change A positive elevation indicates that the outlet is higher than theinlet.


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6-6

Schedule Numbers:

Carbon Steel:

10, 20, 30, 40, 60, 80, 100, 120, 140, 160, STD, XS, XXS

Stainless Steel:

5S, 10S, 40S, 80S

6.2.3 Fittings TabA list of pipe fittings may be added to the pipe segment. These fittingswill be modeled as an additional equivalent length applied linearly over

Material The pipe material, either Carbon Steel or Stainless Steel.

Roughness The surface roughness of the pipe segment. Whenever a material isselected, the absolute roughness is initialized to the default value forthe material as defined on the Preferences view. Valid values are

between 0.00001 inches and 0.1 inches.ThermalConivity

The thermal conductivity of the pipe wall. This is used by the heattransfer calculations when these are enabled.

NominalDiameter

The nominal pipe diameter used to describe the pipe size. For pipeswith a nominal diameter of 14 inches or more, this will be the sameas the outside diameter of the pipe.

ScheduleNumber

If a pipe schedule other than "-" is selected, you will be able toselect a nominal pipe diameter from the pipe databases. It will notbe necessary to specify the internal diameter or the wall thicknessfor the pipe.If you select "-" you will be unable to select a nominal pipe diameterfrom the pipe databases and you will then have to specify both theinternal diameter and wall thickness for the pipe.

InternalDiameter

The pipe diameter used for the pressure drop calculations.

Wall Thickness The thickness of the pipe wall. Valid values are any positive numberor zero.

Pipe Class andSizeable drop-down list

If you want the pipe segment to be resized by sizing calculations,the Sizeable option should be set to Yes. You might set the Sizeableoption to No when debottlenecking an existing plant containingsections of the flare network that would be difficult to change.Setting sizeable to No for these pipes would prevent sizingcalculations from changing their size.Set the Use Pipe Class option to Yes to restrict the pipe sizes tothose defined by the Pipe Class tool.


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the physical length of the pipe segment.


From the Database Fitting list, select the appropriate type of fitting,and then click the Add button to move the selection to the SelectedFitting list. You can select as many fittings as required. The final fittingloss equation, which will be a sum of all the selected fittings, willappear in a display field underneath the Selected Fitting list. ClickLink to transfer the coefficients for this equation into the Fittings Lossfield, while maintaining the list of fittings. Click Paste to transfer thecoefficients for the fitting equation into the Fittings Loss field on thePipe Editor view. The selected list of fittings will not be retained. Toremove the selected fitting individually, select the fitting and click the

Figure 6.5


Length Multiplier The length of the pipe is multiplied by this value to determine theequivalent length used for the pressure drop calculation. If leftblank then the value on the Calculation Options Editor is used.This option is useful for making an allowance for bends and otherfittings if these are not known.

Fittings Loss The fittings "K" factor is calculated from the following equation inwhich Ft is the friction factor for fully developed turbulent flow:K = A + BFtValid values are any positive number or 0.

External HTC This is the outside heat transfer coefficient.


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6-8

Delete button.

6.2.4 Heat Transfer TabThe pipe segment may perform calculations taking into account heattransfer with the external air.


Note: The network cannot be sized correctly if you specify

equivalent length data to model fittings losses, since theequivalent length of any pipe fitting is a function of the pipediameter and will therefore be incorrect when the diameterschange.

Figure 6.6


External Conditions Group

External Medium Select the external medium. Two options arecurrently available 1. Air & 2. Sea Water

Temperature Enter the temperature of the external air. If thisfield is left blank then the global value set via theCalculation Options view is used.

External Medium Velocity Enter the velocity of the external medium. If thisfield is left blank then the global value set via theCalculation Options view is used.


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Heat Transfer Enabled This drop-down list selects whether heat transfercalculations are to be performed for the pipe.

Furthermore, setting only enables heat transfercalculations if the Enable Heat Transfer option isalso selected in the Calculation Options view.

External Radiative HTC This drop-down list selects whether or not theexternal Radiative heat transfer coefficient isincluded within the heat transfer calculations

Emissivity Enter the fractional Emissivity to be used forRadiative heat transfer calculations.

Multiple Element Calculation This drop-down list selects whether the heattransfer calculation is done using a single elementor the same number of elements as the pressuredrop calculation. If Yes is selected then the heattransfer calculation sues the same number ofelements as the pressure drop calculation.

Insulation Group

Description A brief description to identify the type of pipeinsulation.

Thickness Supply the insulation thickness.

Thermal Conductivity Enter the insulation thermal conductivity.

Heating Group

Outlet Temp You can explicitly set an outlet temperature forthis segment, or leave it blank. A heater in a flareknockout drum is an example of processequipment that may require a fixed outlettemperature. Valid values are between -260oC and999 oC.

Duty Enter the heating duty and the outlet temperaturewill be calculated based on the inlet temperatureand the defined duty.



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6.2.5 Methods Tab

Calculation methods are specified on this tab.

When you aresizing a UniSim

Flare system, theinitial pipediameters mayaffect thesolution whenthere is a liquidphase and theliquid knockoutdrum is modeled.You shouldinitially size anetwork usingvapor phasemethods.


Figure 6.7


VLE Method Group

VLE Method The options for the Vapor-Liquid Equilibrium calculationsare as follows (see Appendix A - Theoretical Basis for moredetails):Compressible Gas - Real Gas relationshipPeng Robinson - Peng Robinson Equation of StateSoave Redlich Kwong - Soave Redlich Kwong Equation ofStateVapor Pressure - Vapor Pressure method as described inAPI Technical Data Book Volume 113.Model Default - If this is selected, the Default method forthe VLE method (as defined on the Calculation OptionsEditor view) will be used.


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Pressure Drop Group

Horizontal and Inclined

Pipes

The Horizontal/Inclined methods apply only when you have

selected Two-Phase pressure drop. The options are:Isothermal Gas - This is a compressible gas method thatassumes isothermal expansion of the gas as it passes alongthe pipe. UniSim Flare uses averaged properties of the fluidover the length of the pipe. The outlet temperature fromthe pipe is calculated by adiabatic heat balance either withor without heat transfer. Pressure losses due to change inelevation are ignored.Adiabatic Gas - This is a compressible gas method thatassumes adiabatic expansion of the gas as it passes alongthe pipe. As with the Isothermal Gas method, pressurelosses due to changes in elevation are ignored.Beggs & Brill - The Beggs and Brill method is based on workdone with an air-water mixture at many differentconditions, and is applicable for inclined flow. For moredetails, see Section A - Theoretical Basis.

Dukler - Dukler breaks the pressure drop in two-phasesystems into three components - friction, elevation andacceleration. Each component is evaluated independentlyand added algebraically to determine the overall pressuredrop. For more details, see Section A - TheoreticalBasis.Lockhart Martinelli - Lockhart Martinelli correlations modelsthe two phase pressure drop in terms of a single phasepressure drop multiplied by a correction factor. Accelerationchanges are not included.Beggs and Brill (No Acc.) - The Beggs and Brill methodswithout the acceleration term.Beggs and Brill (Homog.) - The Beggs and Brill methodswith a homogeneous acceleration term.Model Default - If this is selected, the Default method for

the Horizontal/Inclined method (as defined on theCalculation Options Editor view) will be used.



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Vertical Pipes The Vertical method applies only when you have selectedTwo-Phase pressure drop. The options are:

Isothermal Gas - This is a compressible gas method thatassumes isothermal expansion of the gas as it passes alongthe pipe. UniSim Flare uses averaged properties of the fluidover the length of the pipe. The outlet temperature fromthe pipe is calculated by adiabatic heat balance either withor without heat transfer. Pressure losses due to change inelevation are ignored.Adiabatic Gas - This is a compressible gas method thatassumes adiabatic expansion of the gas as it passes alongthe pipe. As with the Isothermal Gas method, pressurelosses due to changes in elevation are ignored.Beggs & Brill - Although the Beggs and Brill method was notoriginally intended for use with vertical pipes, it isnevertheless commonly used for this purpose, and istherefore included as an option for vertical pressure dropmethods. For more details, see Section A - Theoretical

Basis.Dukler - Although the Dukler method is not generallyapplicable to vertical pipes, it is included here to allowcomparison with the other methods.Orkiszewski - This is a pressure drop correlation forvertical, two-phase flow for four different flow regimes -bubble, slug, annular-slug transition and annular mist. Formore details, see Section A - Theoretical Basis.Lockhart Martinelli - Lockhart Martinelli correlations modelsthe two phase pressure drop in terms of a single phasepressure drop multiplied by a correction factor. Accelerationchanges are not included.Beggs and Brill (No Acc.) - The Beggs and Brill methodswithout the acceleration term.Beggs and Brill (Homog.) - The Beggs and Brill methodswith a homogeneous acceleration term.Model Default - If this is selected, the Default method forthe Vertical method (as defined on the Calculation OptionsEditor view) will be used.

Two Phase Elements For two-phase calculations, the pipe segment is divided intoa specified number of elements. On each element, energyand material balances are solved along with the pressuredrop correlation. In simulations involving high heat transferrates, many increments may be necessary, due to the non-linearity of the temperature profile. Obviously, as thenumber of increments increases, so does the calculationtime; therefore, you should try to select a number ofincrements that reflects the required accuracy.

Friction Factor Method The Friction Factor Method applies only when you haveentered a value for friction factor. The options are:Round - This method has been maintained primarily for

historical purposes in order for older UniSim Flarecalculations to be matched. It tends to over predict thefriction factor by up to 10% in the fully turbulent region.Chen - It should always be the method of preference sinceit gives better predictions at the fully turbulent flowconditions normally found within flare systems.Model Default - If this is selected, the Default method forthe Friction Factor Method (as defined on the CalculationOptions Editor view) will be used.

Ignore Downflow HeadRecover

The Elevation Pressure change may be ignored fordownflow (negative elevation change).



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Pipe Network 6-13

6-13

6.2.6 Summary TabThe results of the calculation are displayed.

6.2.7 Multiple EditingYou can edit multiple pipe segments simultaneously by highlightingthem in the Pipe Manager with the mouse cursor while keeping the shiftkey pressed. After you have finished selecting pipe segments, doubleclick any of them to open the common Pipe Editor view.

The common pipe editor view differs from that of the single pipe editorview in the following respects:

Only fields that can be edited in multiple mode are displayed. Drop-down list boxes have an additional entry, *. This entry

indicates that the value should remain at the pre edit value.

Solver Group

Damping Factor The damping factor used in the iterative solution procedure.

If this is left blank, the value in the Calculation OptionsEditor view is used.

Figure 6.8



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6-14

In the following figure of the Dimensions tab; we enter * for theLength and Elevation Change fields to indicate that these mustnot be changed. We specify new values for the Roughness andthe Thermal Conductivity. We select * for the Use Class and

Sizeable drop down lists to indicate that these must be changed.

6.2.8 Pipe Class EditorThe Pipe Class Editor allows you to edit the allowable schedules for eachnominal diameter, for both Carbon Steel and Stainless Steel, duringsizing calculations. It also allows you to restrict the range of pipe sizesthat may be selected by UniSim Flare during design calculations.

Figure 6.9


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Pipe Network 6-15

6-15

To access the Pipe Class Editor, select Pipe Class from the Tools menu.

Figure 6.10

Note: If you have selected Use Pipe Class When Sizing in theRun Options view, these are the schedules which will beused.


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6-16


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Nodes 7-1

7-1

7 Nodes

7.1 Node Manager................................................................................ 2

7.2 Ignoring/Restoring Nodes............................................................. 2

7.3 Connection Nodes.......................................................................... 3

7.3.1 Connector............................................................................... 4

7.3.2 Flow Bleed .............................................................................. 7

7.3.3 Horizontal Separator ................................................................ 97.3.4 Orifice Plate ...........................................................................14

7.3.5 Tee .......................................................................................18

7.3.6 Vertical Separator ...................................................................23

7.4 Boundary Nodes ...........................................................................28

7.4.1 Control Valve..........................................................................28

7.4.2 Relief Valve............................................................................37

7.4.3 Source Tools...........................................................................45

7.4.4 Flare Tip ................................................................................46


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7-2 Node Manager

7-2

Pipes are connected via nodes, which can be added, edited and deletedfrom the Node Manager. Sources are also added through the NodeManager view.

7.1 Node Manager1. To access the Node Manager, select Nodes from the Build menu.

The following buttons are available:

7.2 Ignoring/Restoring NodesWhen you ignore a single node, all upstream nodes are automaticallyignored.

Figure 7.1

Button Description

Add You will be prompted to select the type of node. This new node willbe named with a number depending upon the number of nodes ofthat type already added.

Edit Allows you to edit the currently highlighted node. The form varies,depending on the type of node, as discussed below.

Delete Allows you to remove the currently highlighted node.

Sort Sort the nodes list alphabetically (in descending order) either byname or location or type of node.

Up andDown Arrow

Move the highlighted nodes up and down the list.

Swap Swap the two selected nodes in the Node list.

OK Closes the view.


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Nodes 7-3

7-3

You can ignore single or multiple nodes within the model. When youignore a single node, all upstream nodes are automatically ignored.This enables you to do what if type calculations, where part of the

network can be excluded from the calculation without the need fordeletion and reinstallation of the appropriate nodes.

To ignore a node:

1. Open the node editor view of the node that you want to ignore.2. On the Connections tab, activate the Ignore checkbox. The

following figure shows this for a connector node.

To restore a node that has previously been ignored:

1. Open the node editor view of the node that you want to restore.2. On the Connections tab, deactivate the Ignore checkbox.

7.3 Connection NodesThe following types of connection nodes are available in UniSim Flare. Aconnection node is one that links two or more pipe segments.

Connector Flow Bleed Horizontal Separator Orifice Plate Tee Vertical Separator.

Figure 7.2


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7-4 Connection Nodes

7-4

7.3.1 Connector

The connector is used to model the connection of two pipes. Thediameters of each pipe may be different.

Connections TabThe name of the connector and connectivity information is specifiedhere.

The location can have an alphanumeric name. This feature is useful forlarge flowsheets, because you can provide a different "location" nameto different sections to make it more comprehensible.


Figure 7.3

Field Description

Name The alphanumeric description of the node (e.g. - HP Connect 1).

Location You may want to specify the location of the node in the plant.

Upstream/Downstream

Either type in the name of the pipe segment or select from the drop-down list.

At You can specify the end of the pipe segment attached to the

connector.Ignore Select the ignore checkbox to ignore this connector in thecalculations. Clear the checkbox to re-enable it.


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Nodes 7-5

7-5

Calculations TabCalculation methods are specified here.


Figure 7.4

Field Description

Theta Specify the connector expansion angle. If not defined, it will becalculated to the length.

Length Enter the connector length. If not defined, it will be calculatedfrom theta.

Fitting LossMethod

The available options are;Equal Static Pressure Pressure drop calculation is ignored andstatic pressure is balanced.Calculated Pressure drop is calculated in accordance with theSwage method.Equal Total Pressure - Pressure drop calculation is ignored andtotal pressure is balanced.

IsothermalPressure Drop

If this option is set to Yes, the inlet temperatures used for thesize change calculations in the connector will not update duringiterative calculations for pressure loss i.e. a PT flash will be usedto update the inlet properties. If the option is set to No then amore rigorous PH flash will be used to update the inletproperties.The connector will do one size change calculation between theinlet and outlet diameters selecting expansion or contraction asappropriate.

Setting this option to Yes can speed up calculations in somecases at cost of a minor loss of accuracy.


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7-6 Connection Nodes

7-6

Summary TabThe result of the calculations at each of the pipe connections isdisplayed.

Swage Group

Two Phase

Correction

If this option is set to Yes then the pressure loss coefficient in

two phase flow will be calculated using properties corrected forliquid slip. If set to No then the homogenous properties of thefluid will be used in calculating the pressure loss coefficient.

Swage Method The following options are available:Compressible - pressure losses will be calculated assumingcompressible flow through the connector at all times.Incompressible (Crane) - pressure losses will be calculatedassuming incompressible flow through the connector at alltimes. Loss coefficients are calculated using Crane coefficients.Transition - pressure losses will be calculated initially using theassumption of incompressible flow. If the pressure lossexpressed as a percentage of the inlet pressure is greater thanthe defined compressible transition value then the pressuredrop will be recalculated using the compressible flow method.Incompressible (HTFS) - pressure losses will be calculated

assuming incompre

Documents

UniSim Flare Reference Guide