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Report On
1. CONSOLIDATION OF HYDROPROCESSING VESSEL DESIGN-
EXCEL TOOLS WITH WIN 254
2. HYDRAULIC FLOW DIAGRAM MODULES DEVELOPMENT
BY
Vatika
(2010A1PS314G)
AT
UOP IPL, Gurgaon
A Practice School-II station of
BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE-PILANI
15st June, 2014
2
REPORT ON
1. CONSOLIDATION OF HYDROPROCESSING VESSEL DESIGN-
EXCEL TOOLS WITH WIN 254
2. HYDRAULIC FLOW DIAGRAM MODULES DEVELOPMENT
BY
Vatika
(2010A1PS314G)
AT
UOP India Pvt. Ltd., Gurgaon
Report submitted for the partial fulfilment of the course
BITS C412 / BITS G639: Practice School – II
BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE-PILANI
15st June, 2014
3
NO DUES CERTIFICATE
PS-II Station: UOP, Gurgaon
Centre: Gurgaon
Date: 15th June, 2014
Name: Vatika ID No.: 2010A1PS314G
Will be completing his/her Practice School Programme on 19th July, 2012. In case
he/she has any dues, please report it below against your name. In case he/she has
no dues, please write NO DUES and sign.
1 Organization Coordinator
2 Professional Expert
3 Librarian
4 Accounts Section
5 PS Faculty
6 Any other
Signature of the PS Faculty
4
BIRLA INSTITUTE OF TECHNOLOGY AND SCIENCE
PILANI (RAJASTHAN)
PRACTICE SCHOOL DIVISION
Response Option Sheet
Station: UOP IPL Centre: Gurgaon ID No | Name: 2010A1PS314G | Vatika
Title(s) of Project(s): (1) Consolidation of Hydroprocessing Vessel Design-Excel Tools
with Software (2) Hydraulic Flow Diagram Modules Development
Usefulness of the project to the on-campus courses of study in various disciplines:
Code numbers 1, 2, 4 are applicable Project should be scrutinized keeping in view of
the following response options. Write Course No. and Course Name against the option
under which the project comes. (Refer Bulletin for course No. and course Name.)
Code No.
Response Option Course No.(s) & Name
1 A new course can be designed out of this project. No
2 The project can help modification of the course content of
some of the existing Courses
No
3 The project can be used directly in some of the existing Compulsory Discipline Courses (CDC)/ Discipline Courses
Other than Compulsory (DCOC)/ Emerging Area (EA), etc. Courses
No
4 The project can be used in preparatory courses like Analysis and Application Oriented Courses (AAOC)/ Engineering Science (ES)/ Technical Art (TA) and Core Courses.
No
5 This project cannot come under any of the above mentioned options as it relates to the professional work of the host organization.
Yes
Signature of Student
Signature of PS Faculty
Date: 15th June, 2014 Date: 15th June, 2014
5
Acknowledgements
I would like to express my sincere thanks to BITS Pilani Practice School Division and
UOP India Private Limited, Gurgaon for providing me this wonderful opportunity. I
would like to thank my PS II mentor, at UOP, Mr Ramesh Subramaniam, Senior
Manager-Naphtha, Aromatics and Olefin. Then I find this opportunity to thank the
project experts Mr. Pankaj K Srivastava, Ms. Neeru Gupta and Mr. Anup Dhaigude. I
would also like to express my gratitude to my training mentors Mr. Abhishek Kadam
and Mr. Abhishek Pahwa. I treasure the learning the company has provided and I am
thankful for the resources to carry out the project work.
I am thankful to Ms. Shailja Singhdev Sodhi (PS II faculty for UOP) for her constant
support and visits. I am also thankful to Mr. Santosh Khandgave (PS II faculty from
Pune) for organizing online presentations and for his guidance.
My gratitude goes to every single person associated directly or indirectly with my
internship for contributing to my knowledge and personality, one way or the other.
Vatika
6
BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE-PILANI
PILANI (RAJASTHAN)
Practice School Division
Station: UOP IPL Centre: Gurgaon Date of start: 20th January, 2014 Date of submission: 15th March, 2014 Duration: 6 months End Date: 19th July, 2014
Title of Project 1: Consolidation of Hydroprocessing Vessel Design-Excel Tools with
Win 254
ID NO. Name Discipline
2010A1PS314G Vatika B.E. (Hons.) Chemical Engineering
Name of Project Expert: Designation: Mr. Pankaj K Srivastava Manager- Hydroprocessing Mr. Sreemanta Goswami Sr. Process Technology Engineer
Name of PS Faculty: Ms. Shailja Singhdev Sodhi and Mr. Santosh Khandgave
Key Words: Vertical Separator, Horizontal Separator, Flash Drum, coalescer, drop
leg, residence time, surge time, clearance time
Project Areas: Vessel Design
Abstract 1: The purpose of the project is to find out the difference in the working of
the excel tool and vessel design software (Win254). Then to specify template so as to
consolidate the process and eliminate use of excel tool. The vessel under
consideration include: Hot Separator, Cold Separator, Hot Flash Drum and Cold
Flash Drum. This involved study of vessel design basis and the process and project
manual for Hydroprocessing Unit. The excel document was made to specify
similarities and differences in the two methods. This exercise was done for two
projects: Unionfining and Unicracking. Then appropriate recommendations were
given.
Signature of Student Signature of PS Faculty
7
BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE-PILANI
PILANI (RAJASTHAN)
Practice School Division
Station: UOP IPL Centre: Gurgaon Date of start: 20th January, 2014 Date of submission: 15th March, 2014 Duration: 6 months End Date: 19th July, 2014
Title of Project 2: Hydraulic Flow Diagram Modules Development
ID NO. Name Discipline
2010A1PS314G Vatika B.E. (Hons.) Chemical Engineering Name of Project Expert: Designation:
Mr. Anup Dhaigude Manager- Naphtha and Aromatics Ms. Neeru Gupta Group Leader- Oleflex
Name of PS Faculty: Ms. Shailja Singhdev Sodhi and Mr. Santosh Khandgave
Key Words: Equivalent Length, Fractionation, Internal Reflux, Condensing systems,
Reboiler, Multiple Reciprocating Compressors, Heat Exchangers, Two Phase Flow
Project Areas: Hydraulics
Abstract 2: This project has to two objectives. First is to develop hydraulic flow
diagram (HFDs) modules for all processes under consideration. Second is to make
spreadsheets, for NHP (hydraulics software), which are consistent with standard
Unisim simulation (process modelling sotware). The standard HFDs is developed for
Isomar, Tatoray, Benzene-Toluene (BT) Fractionation, Parex, Sulfolane, C3 Oleflex
and C3-C4 Oleflex. The Unisim simulations were referred to develop spreadsheet for
NHP. This was done for C3 Oleflex Fractionation Section and C3-C4 Oleflex
Fractionation and Reactor Sections. For this understanding, Process Flow Diagrams
(PFDs) of all processes were referred. Equivalent length, fractionation column,
overhead vapor condensing system, reboiler, compressor and heat exchanger theories
were studied. Also the HFDs of earlier projects were referred. An excel sheet to
calculate internal reflux for BT column was prepared.
Signature of Student Signature of PS Faculty
8
Table of Contents
Acknowledgements .................................................................................................................................................... 5
Abstract 1 ................................................................................................................................................................... 6
Abstract 2 ................................................................................................................................................................... 7
1. About UOP ....................................................................................................................................................... 13
1.1 Products ................................................................................................................................................... 13
1.2 Continued Dedication to Innovation ........................................................................................................ 14
2. Project 1: Consolidation of Hydroprocessing Vessel Design-Excel Tools with Win 254 .................................. 15
2.1 Objective .................................................................................................................................................. 15
2.2 Vessels under consideration .................................................................................................................... 15
2.3 Theory ...................................................................................................................................................... 15
2.3.1 Orientation of the Vessel ................................................................................................................. 16
2.3.2 Surge and Residence time ................................................................................................................ 16
2.3.3 Clearance.......................................................................................................................................... 16
2.3.4 Vessel Heads .................................................................................................................................... 17
2.3.5 Inlet Devices ..................................................................................................................................... 17
2.3.6 Internals ........................................................................................................................................... 18
2.4 Processes .................................................................................................................................................. 18
2.4.1 Unicracking ....................................................................................................................................... 18
2.4.2 Unionfining ....................................................................................................................................... 18
2.5 Methodology ............................................................................................................................................ 19
2.5.1 Hot Separator ................................................................................................................................... 19
2.5.2 Hot Flash Drum ................................................................................................................................ 21
2.5.3 Cold Separator ................................................................................................................................. 22
2.5.4 Cold Flash Drum ............................................................................................................................... 26
2.6 Discussion of results ................................................................................................................................. 27
2.6.1 Hot Separator ................................................................................................................................... 27
2.6.2 Hot Flash Drum ................................................................................................................................ 27
2.6.3 Cold Separator ................................................................................................................................. 28
2.6.4 Cold Flash Drum ............................................................................................................................... 28
9
2.7 Conclusion ................................................................................................................................................ 29
3. Project 2: Hydraulic Flow Diagram Modules Development ............................................................................. 31
3.1 Objective .................................................................................................................................................. 31
3.2 Processes under consideration ................................................................................................................ 31
3.3 Theory ...................................................................................................................................................... 31
3.3.1 Hydraulics ......................................................................................................................................... 31
3.3.1.1 Equivalent Length ........................................................................................................................ 32
3.3.1.2 Pipe Service Code ......................................................................................................................... 32
3.3.2 Two Phase Flow................................................................................................................................ 32
3.3.3 Fractionation Column ...................................................................................................................... 34
3.3.3.1 Fractionator Condensing System ..................................................................................................... 34
3.3.3.2 Fractionation Composition Control.............................................................................................. 35
3.3.3.3 Reboilers ...................................................................................................................................... 35
3.3.4 Heat Exchanger ................................................................................................................................ 36
3.3.4.1 Steam Side Controls ..................................................................................................................... 36
3.3.4.2 Steam Condition ........................................................................................................................... 37
3.3.4.3 Types ............................................................................................................................................ 37
3.4 Processes .................................................................................................................................................. 37
3.4.1 Sulfolane .......................................................................................................................................... 37
3.4.2 Benzene Toluene Fractionation ....................................................................................................... 37
3.4.3 Parex ................................................................................................................................................ 38
3.4.4 Isomar .............................................................................................................................................. 38
3.4.5 Tatoray ............................................................................................................................................. 38
3.4.6 C3 Oleflex ......................................................................................................................................... 38
3.4.7 C3 C4 Oleflex .................................................................................................................................... 39
3.5 Methodology ............................................................................................................................................ 39
3.6 Discussion of Results ................................................................................................................................ 39
3.6 Conclusion ...................................................................................................................................................... 40
4 Miscellaneous Activities ................................................................................................................................... 41
5 Appendix .......................................................................................................................................................... 42
5.1 Appendix A ............................................................................................................................................... 42
5.2 Appendix B ............................................................................................................................................... 43
10
6 Glossary ............................................................................................................................................................ 44
7 References ....................................................................................................................................................... 47
11
LIST OF FIGURES
Figure 1 Snapshot of Win 254 for Cold Separator ................................................................................................... 24
Figure 2 Snapshot of Design Session Report for Cold Separator showing diameter corresponding to disentraining
vapor and residence time criteria ............................................................................................................................ 25
Figure 3 Snapshot of Design Session Report for Cold Separator showing tangent length corresponding to
accumulated length ................................................................................................................................................. 26
Figure 4 Boiling in Vertical tube to demonstrate various two phase flow regimes ................................................. 33
12
LIST OF TABLES
Table1: Hot Separator: comparison between Excel tool and Win 254 .................................................................... 27
Table2: Hot Flash Drum: Comparison between Excel tool and Win 254 ................................................................. 27
Table3: Cold Separator: Comparison between Excel tool and Win 254 .................................................................. 27
Table4: Cold Flash Drum: Comparison between Excel tool and Win 254 ................................................................ 28
13
1. About UOP UOP LLC formally known as Universal Oil Products, now a fully owned subsidiary of
Honeywell, is a multinational company developing and delivering technology to the
petroleum refining, gas processing, petrochemical production, and major
manufacturing industries.
When founded in 1914 it was a privately held firm known as the National
Hydrocarbon Company. J. Ogden Armour provided initial seed money and kept the
firm going the first years it lost money. In 1919 the firm's name became Universal Oil
Products. By 1931 Petroleum firms saw a possible competitive advantage to owning
UOP. A consortium of firms banded together to purchase the firm. In August 1988
Union Carbide Corporation and Allied Signal Inc. formed a joint venture combining
UOP Inc., a wholly owned subsidiary of Allied Signal and the Catalyst, Adsorbents
and Process Systems (CAPS) business of Union Carbide. In 2005, Honeywell took
over full ownership when it bought the two halves owned by Union Carbide and Allied
Signal.
Part of Honeywell’s Performance Materials and Technologies (PMT) business group,
UOP is equipped to offer the best, most advanced processes, products and services
around the world. For a century, UOP has been the leading international supplier
and licensor for the petroleum refining, gas processing, petrochemical production and
major manufacturing industries. As a respected pioneer, it is responsible for
developing and implementing some of the most useful, original technologies in the
world.
Today more than 60% of the world’s gasoline and 85% of its bio-degradable
detergents are made using UOP technology.
1.1 Products
UOP products fall into two groupings, physical products that can be seen, and
technology products that provide knowledge and design.
Physical products tend to be items used within a refinery or petrochemical plant to
help convert chemicals into a desired product. Physical products include:
Catalysts
Adsorbents
Equipment
14
Technology products tend to be based upon the ability to convert one chemical into
another, refine crude oil, and separate chemicals from each other. These include
processing solutions for:
Refining
Petrochemicals
Gas
Bio fuels
Besides these, UOP offers following services based upon the company’s extensive
technical knowledge and experience:
Training
Inspection
Design
Optimization
Energy and Carbon Dioxide Management
Ongoing Operation
1.2 Continued Dedication to Innovation
Today, innovation continues to thrive through UOP’s award-winning staff of scientists
and engineers. UOP has nearly 3,000 active patents worldwide, and has generated
thousands more historically, leading to important advances in process technology,
profitability consultation, and equipment design.
UOP is a member company of the American Chemistry Council, and Responsible
Care® is the foundation for sustainability in its business. The Responsible Care®
Management System is used to support our full commitment to comply with legal and
other Health, Safety and Environmental (HS&E) requirements.
15
2. Project 1: Consolidation of Hydroprocessing Vessel Design-Excel Tools with Win 254
2.1 Objective
The objective of the project is to develop a template so as to manipulate the Win 254
(vessel design software) in such a manner that it can give same result as that of the
excel tools.
My objective is also to learn about vessel design and hydro-processing,
2.2 Vessels under consideration
Hot Separator
Hot Flash Drum
Cold Separator
Cold Flash Drum
2.3 Theory
In general the function of a vessel in a process unit is to either provide hold-up time
or to make a separation between the various phases of a mixed process stream. This
separation can be between two or three phases. Project has two vessels (namely hot
separator and flash drum) with vapor-liquid separation. The other two (namely cold
separator and flash drum) have three phase separation.
It should be noted that three kinds of separation operations are considered:
Momentum: by change in velocity direction. This achieved by use of appropriate
distributor.
Gravity: is the function of time and terminal velocity.
Coalescing: achieved use of mesh blanket. This is installed to reduce the tangent
length of the vessel which otherwise becomes very long with gravity separation.
16
2.3.1 Orientation of the Vessel
The selection of the orientation of a gas-liquid separator depends on several factors.
Both vertical and horizontal vessels have their advantages. Depending on the
application one has to decide on the best choice between the alternatives.
Advantages of a vertical vessel are:
a smaller plot area is required
it is easier to remove solids
liquid removal efficiency does not vary with liquid level because the area in the
vessel available for the vapor flow remains constant
generally the vessel volume is smaller
Advantages of a horizontal vessel are:
it is easier to accommodate large liquid slugs
the downward liquid velocity is lower, resulting in improved de-gassing and
foam breakdown
additional to vapor / liquid separation also a vapor/ liquid / liquid separation
can be achieved (e.g. by installing a boot)
2.3.2 Surge and Residence time
The surge time is the duration that the vessel can accommodate inlet rate if the
outgoing cuts off. It is defined as the time for the liquid level to drop from highest
liquid level (HLL) to lowest liquid level (LLL). This usually has specific value based
upon the type of vessel service.
Residence time is the retention time of each phase in the separation compartment of
the vessel, which is the criterion for phase separation. This is the time required for
the liquid level to drop from normal liquid level to full empty. The residence time and
percentage full of vessel are essential for the design of horizontal vessel.
2.3.3 Clearance
It is the minimum distance required between any two internals. This is explained in
detail in the methodology part of the report. The accumulated length of the vessel is
based upon this criterion.
17
2.3.4 Vessel Heads
Elliptical Head
Most vessels have 2:1 elliptical heads, welded to the shell of the vessel. However, in
some cases other types of heads are used. This is used in Hot Flash Drum. The major
alternatives are:
Flat Head
In case of small vertical vessels (diameter less than approximately 30”) often a flanged
top head is used, which also serves to provide access to the vessel. Depending on the
pressure rating, this type of head can either be flat or elliptical, and shall be selected
in consultation with the mechanical engineer.
Hemispherical Head
A hemispherical head should be considered for an extremely large, high-pressure
vessel. This is used in Hot Separator.
Dished Head
A dished head should be considered in the case of a large diameter, low-pressure
vessel.
2.3.5 Inlet Devices
Various inlet devices are available to improve the vapor / liquid separation. Among
others the following inlet devices may be installed:
a deflector baffle
a slotted tee distributor
a half-open pipe
a 90 ° elbow
a tangential inlet with annular ring
For vertical drums, preferably a deflector baffle or a half open pipe shall be selected.
In case of a slug flow regime in the inlet piping, or if high liquid separation efficiency
is required, a tangential inlet nozzle with annular ring can be used. However, in case
high liquid removal efficiency is required, the application of a wire mesh demister is
preferred.
For horizontal drums normally a 90° elbow or a slotted diverter is installed. In some
cases a submerged inlet pipe is installed, but this shall not be done in the case of a
two-phase feed.
18
2.3.6 Internals
After passing through the feed inlet, the vapor stream will still contain liquid in the
form of droplets. The maximum size of these entrained droplets depends on the vapor
up-flow velocity. A separation device can reduce this entrainment significantly. Wire
mesh demisters are the most commonly used as separation device. They are used for
two reasons:
To minimize entrainment
Of the drum services having such a requirement, suction drums for reciprocating
compressors are the most notable examples.
To reduce the size of a vessel
The allowable vapor velocity in a drum can be increased significantly by using a wire
mesh demister. So, when sizing is governed by vapor-liquid separation criteria, this
will result in a smaller diameter of the vessel
Major disadvantages of wire mesh demisters are:
They are not suitable for fouling services
Their liquid removal decreases significantly at reduced throughput
Although the size of the vessel often can be reduced by applying a wire mesh
demister, there are also many services where there is normally no demister installed.
There are several other types of mist eliminators such as vanes, cyclones, and fibre
beds. They are used when conditions are not favourable for wire mesh screens.
Selection criteria for these types of internals are the required efficiency, capacity,
turndown ratio, maximum allowable pressure drop and fouling resistance.
2.4 Processes
2.4.1 Unicracking
This is the hydrocracking process. The feed is catalytically cracked, under high
pressure, so as to reduce its molecular weight in order to produce high value
products with minimum impurities.
2.4.2 Unionfining
Unionfing is the process of hydrotreating. In this the impurities like sulphur, nitrogen
and water, from feed. This is a high pressure endothermic process. This is essential
as the impurities that this process removes are poison for the downstream catalyst.
19
2.5 Methodology
The first step in the given assignment was to go through the theory of vessel design in
the technical manuals. Next step was to understand working of Win 254 which was
done in initial, month long, project training.
This was followed by designing the process vessels under consideration using hand
calculations, excel tools and Win 254. The related data, which included input and
output values and the formulae used, was tabulated and this became the basis of the
variation between the result provided by tools and software.
Following this exercise attention was given to individual vessel so as to eliminate or
minimize the variations.
2.5.1 Hot Separator
This is a vertical vessel with no mesh blanket and is used for vapor-liquid separation.
Size Criteria used in excel tool are:
(1) 3 minutes liquid surge time across level range
(2) 0.05 fps (0.05 ft/s) maximum vertical liquid velocity
(3) Tangent length about 20 ft (6000 mm)
(4) Maximum vapor velocity by following formula:
Where,
Density if liquid (in lb/ft3)
Density if vapor (in lb/ft3)
Besides these, other specifications from project design manual/excel tool are:
(5) The inlet nozzle is 4 ft (1200 mm) above HLL
(6) Minimum liquid level is 1 ft (300 mm) above the bottom tangent
(7) Liquid droplet diameter (for size criteria 4) is 200 micron
The changes made in Win 254 to accommodate above criteria:
Diameter of vapor droplet
20
Vapor droplet diameter is otherwise taken to be default and equals 175 micron. But
following steps give the requisite vapor droplet diameter for 0.05 fps liquid vertical
velocity.
From Stokes law,
Where,
terminal vapor velocity (in fps)
vapor droplet diameter (in ft)
ρ density (in lb/ft3)
μ viscosity (in lb/ft sec)
Subscripts,
V vapor
P particle
L liquid
Also it is known that at velocity of continuous phase (here liquid) equals the terminal
velocity of dispersed phase (here vapor) for separation process.
So
This would give the diameter of vapor droplet which can be entered into the vessel
design software.
Liquid Droplet Diameter
The default value of liquid droplet is 250 micron. Set it equal to 200 micron as
mentioned in excel tool.
Clearance time between bottom of inlet and HLL
21
For clearance time the 4 ft (1200 mm) is the distance mentioned in excel tool and to
calculate the requisite time following formula is used:
Where,
required clearance time (in min) to be inputted in software.
diameter of vessel (in ft)
clearance distance (in ft)
Liquid flow rate (in GPM)
2.5.2 Hot Flash Drum
This is similar to hot separator, a vertical vessel with two phase separation. The same
steps are followed as in hot separator. The difference between hot separator and hot
flash drum is the criteria deciding the diameter and the clearance time calculation.
(Note that before designing hot flash drum, hot separator has to be designed as
dimensions of latter are used in former vessel design.)
Size Criteria used in excel tool are:
(1) 3 to 5 surge liquid surge time across level range
(2) 0.05 fps maximum vertical liquid velocity
(3) Hold all the Hot Separator liquid from HLL
Besides these, other specifications from project design manual/excel tool are:
(4) The diameter of hot flash drum is same as hot separator
(5) Diameter of liquid droplet 200 micron
The changes made in Win 254 to accommodate above criteria:
Diameter of vapor droplet
Use equation [2] to find vapor diameter and enter that value in vessel design
software.
Diameter of liquid droplet
22
Set it equal to 200 micron.
Diameter of vessel
Set this value equal to diameter of the hot separator.
Clearance time between bottom of inlet and HLL
Unlike hot separator, here clearance length is not fixed.
The clearance length in this case is such as to accommodate the inventory from the
hot separator for relief purpose. So here the equation [3] would change as follows:
Where,
HLL height of highest liquid level (in ft) in hot separator
volume of maximum liquid level possible in hot separator (in )
liquid volume in the head (here head is hemispherical) of hot separator
(in )
2.5.3 Cold Separator
This is a 50% full horizontal vessel with three phase separation (vapor-liquid-liquid).
It has a vertical coalescer (mesh blanket) and drop leg to enhance liquid-liquid
separation.
Size Criteria used in excel tool are:
(1) 5 min. residence time @ normal liquid level
(2) 6 ft/min max through mesh blanket
(3) Vapor velocity to prevent entrainment
(4) Water boot residence 2.5 min
(5) 200 micron water droplet size
Besides these, other specifications from project design manual/excel tool are:
(6) Droplet size for light liquid dispersed in vapor is 200 micron
(7) Residence time should be 5 to 6 minutes
23
(8) Surge time should be between 5 and 10 minutes
(9) Raised vortex breaker height 150 mm (6”)
The changes made in Win 254 to accommodate above criteria:
Diameter of light liquid dispersed in vapor
Set it equal to 200 micron.
Diameter of heavy liquid dispersed in liquid
Set it equal to 200 micron.
Diameter of vessel
The excel tool uses the residence time as the criteria for deciding the vessel volume
while the vessel design software take into account: disentrainment of vapor from
liquid, gravity settlement of light liquid from vapor and heavy liquid from light, the
maximum allowable velocity through the mesh blanket and residence time. So to get
the diameter, as that calculated by excel tool, use the residence time as the deciding
criteria in the software as well.
Besides the maximum liquid velocity through the mesh blanket is more in excel tool
(6 fps) than in the vessel design software (3 fps). This implies the diameter output of
this same criteria in software will be more than that of the excel tool. So follow the
following routine to make residence time as the major deciding factor for diameter of
the vessel in vessel design software.
When all the mandatory fields are entered Vessel design software vessel draft open
‘Design Section Report’.
24
Figure 1 Snapshot of Win 254 for Cold Separator
From the design section report (an excel sheet) look for the calculated vessel diameter
liquid residence time and diameter required for disentraining vapor from the liquid.
25
Figure 2 Snapshot of Design Session Report for Cold Separator showing diameter corresponding to disentraining vapor and residence time criteria
Then choose the maximum of the two values. Force the roundup to next 100mm of
this value into vessel design software.
26
Figure 3 Snapshot of Design Session Report for Cold Separator showing tangent length corresponding to accumulated length
The tangent length is corresponding to the corresponding diameter roundup to next
100 mm. Note here that if the accumulated length (from excel sheet) is more than the
above chosen tangent length, force the roundup to next 100 mm of the accumulated
length.
2.5.4 Cold Flash Drum
This is a full horizontal vessel for three phase separation (vapor-liquid-liquid). It has
a vertical coalescer (mesh blanket) and drop leg to enhance liquid-liquid separation.
Percentage full of vessel is not fixed and depends upon the inventory of hot separator.
Size Criteria used in excel tool are:
(1) Residence time of 5 minutes (adjust NLL to get 5 minute residence time)
(2) 6 ft/min max through mesh blanket
(3) Vapor velocity to prevent entrainment
(4) Water boot residence 2.5 min and downward velocity < 1.0 ft/min
(5) Hold all the upstream separator liquid from high liquid level with 35% margin
Besides these, other specifications from project design manual/excel tool are:
(6) Droplet size for light liquid dispersed in vapor is 100 micron
(7) Droplet size for heavy liquid dispersed in light liquid is 200 micron
(8) Raised vortex breaker height 150 mm (6”)
(9) Inlet of sour water from the hot separator drop leg to the bottom of the vessel
before coalescer
(10) Boot diameter is same as Cold Separator.
27
The changes made in Win 254 to accommodate above criteria:
Diameter of light liquid dispersed in vapor
Set it equal to 200 micron.
Diameter of heavy liquid dispersed in liquid
Set it equal to 200 micron.
Diameter of vessel
Follow the same steps as in cold separator. When all the mandatory data is entered
in vessel design software, open ‘Design Section Report’. In this go through the
calculated vessel values of the diameter. Select the maximum among these, except
the diameter for ‘maximum liquid velocity (total) @ (3 ft/min)’. This is so because the
maximum liquid velocity (total) allowed in this vessel is 6 ft/min.
Boot Diameter
The water drop leg diameter in the excel tool is taken to be same as that in Cold
Separator. So input this value from the result of cold Separator,
2.6 Discussion of results
The above methodology is followed for two cases:
Distillate Unionfining (Project: Vung Ro Refinery)
Unicracking (Project: Shandong Super Energy Industrial Company)
2.6.1 Hot Separator
The diameter of the vessel designed by excel-tool and Vessel design software match. It
should be noted that the vessel tangent length in case of software is more (100-
200mm) which can be accepted, as this can be owing to the round-off error. The
vessel level range also lie within the same variation as the tangent length. It should
be noted here the minimum liquid level in case of excel-tool is 1 ft (300mm) which is
different from vessel design software value of 0.5 ft (150 mm). This can not be forced.
2.6.2 Hot Flash Drum
When the diameter of this vessel is set equal to that of the hot separator and
requisite changes are made as mentioned in methodology, the tangent length of the
28
vessel is (100-300mm) less then that specified in the excel-tool. However the level
range is with the variation of (0-100mm).
If the diameter is not set equal to hot separator, then the Vessel design software gives
diameter of hot flash drum 100mm less than required. But this increases the tangent
length accordingly.
2.6.3 Cold Separator
Considering the residence time as the deciding factor for the vessel diameter, the said
parameter (diameter) has the similar value in two cases. However, the tangent length
is smaller than that the excel tool provides. It should be noted here, if the output of
vessel design software (the one with smaller tangent length) is made input of excel-
tool it is found that the vessel dimensions satisfy all the criteria mentioned in the
excel tool. Also note that the overall volume is greater for the dimensions calculated
by vessel design software.
2.6.4 Cold Flash Drum
The results for this vessel do not match after following the steps mentioned in the
methodology. There is more than one reason at work here.
First, the allowable maximum liquid velocity (total) through the coalescer is 6 ft/min
but Vessel design software take 3 ft/min as the default value. This cannot be forced
in the software. Note that the lesser value of maximum velocity implies larger liberal
design.
Second, the cold flash drum holds the upstream liquid inventory. This is value is
adjusted via liquid full of the vessel. However Win 254 provides only limited choices
for the same, that are 50/100/80/66/58/42/34 % full. Note the required value of
percentage full to be used is less than 34%. So if 34% is used, the dimensions are
lesser than required (given by excel tool) and these smaller dimensions cannot
accommodate upstream inventory with 35% margin.
Third, the inlet to the vessel cannot be provided from bottom before the coalescer. So
the software assumes that all total feed (vapor-liquid-liquid) enter from the top inlet
of the vessel. This may result in longer tangent length than required.
Fourth, vessel design software uses default L/D of 3 but for this vessel L/D in excel
tool is less than 3 and is not fixed.
29
2.7 Conclusion
So based upon the results and their discussion out of four vessels three (Hot
Separator, Hot Flash Drum and Cold Separator) can be design directly in Vessel
design software with small change in methodology which is otherwise followed. The
following tables give a summary of differences and similarity in excel-tools and Vessel
design software:
Hot Separator
Excel Tool Win 254
3 minutes liquid surge time across level range
3 minutes liquid surge time across level range
0.05 fps maximum vertical liquid velocity Droplet diameter of vapor
Maximum vapor velocity Droplet diameter of liquid (200 micron)
Distance between HLL and bottom of inlet line
Clearance time between HLL and bottom of inlet line
Table1: Hot Separator: Comparison between Excel tool and Win 254
Hot Flash Drum
Excel Tool Win 254
3 to 5 minutes liquid surge time across level range
3 minutes liquid surge time across level range
0.05 fps maximum vertical liquid velocity Droplet diameter of vapor
Hold all the Hot Separator liquid from HLL Clearance time between HLL and bottom of
inlet line
Diameter is same as Hot Separator Diameter is same as Hot Separator
Liquid droplet diameter is 200 micron Liquid droplet diameter is 200 micron
Table2: Hot Flash Drum: Comparison between Excel tool and Win 254
Cold Separator
Excel Tool Win 254
5 min. residence time @ normal liquid level 5 min. residence time
6 ft/min max through mesh blanket 3 ft/min max through mesh blanket
Vapor velocity to prevent entrainment Consider this as one of the criteria for selecting vessel diameter
Water boot residence 2.5 min Water boot residence 2.5 min. Consider this as the criteria for selecting drop leg diameter
200 micron water droplet size 200 micron water droplet size
Droplet size for light liquid dispersed in Droplet size for light liquid dispersed in
30
vapor is 200 micron vapor is 200 micron
Table3: Cold Separator: Comparison between Excel tool and Win 254
Cold Flash Drum
Excel Tool Win 254
Residence time of 5 minutes (adjust NLL to get 5 minute residence time)
5 min. residence time but NLL can not be fine tuned. Only percentage full can
selected
6 ft/min max through mesh blanket 3 ft/min max through mesh blanket
Vapor velocity to prevent entrainment Consider this as one of the criteria for selecting vessel diameter
Water boot residence 2.5 min and downward velocity < 1.0 ft/min. But diameter of boot equals diameter of boot in
Cold Separator.
Water boot residence 2.5 min and downward velocity < 1.0 ft/min. But diameter of boot equals diameter of boot in
Cold Separator.
Hold all the upstream separator liquid from
high liquid level with 35% margin
This can not be fine tuned. Only
percentage full can selected
Droplet size for light liquid dispersed in vapor is 100 micron
Droplet size for light liquid dispersed in vapor is 100 micron
Droplet size for heavy liquid dispersed in light liquid is 200 micron
Droplet size for heavy liquid dispersed in light liquid is 200 micron
Inlet of sour water from the hot separator drop leg to the bottom of the vessel before
coalescer
This can not be incorporated
Table4: Cold Flash Drum: Comparison between Excel tool and Win 254
31
3. Project 2: Hydraulic Flow Diagram Modules Development
3.1 Objective
This project has to two objectives. First is to develop hydraulic flow diagram modules
for all processes under consideration. Second is to make spreadsheets, for NHP
(hydralics software), which are consistent with standard Unisim (process modelling
software) simulation.
My objective is also to learn about processes under consideration, hydraulics,
fractionation systems and heat exchangers.
3.2 Processes under consideration
HFD modules for:
Sulfolane
Benzene Toluene Fractionation
Parex
Isomar
Tatoray
C3 Oleflex
C3 C4 Oleflex
Preparation of spreadsheets for:
C3 Oleflex Fractionation Section
C3 C4 Oleflex Fractionation Section
C3 C4 Oleflex Reactor Section
3.3 Theory
3.3.1 Hydraulics
The Process Hydraulics is not based upon the exact plot plan but on a typical plot
plan. In this instead of using exact pipe length and fittings, equivalent length is used.
Though the contractor has to carry out the exact hydraulics based upon the specific
unit, process hydraulics is important as it helps in determining line sizes, pump and
compressor head requirement, vessel skirt height, control valve requirement and
alternate and turndown scenario. These are important for customer as it helps in
placing orders.
32
3.3.1.1 Equivalent Length
Based upon the past experience, equivalent lengths are calculated.
3.3.1.2 Pipe Service Code
Based upon the service a line provides, appropriate service code is allotted to that
line. For example the overhead line from fractionation has a service code for ‘column
overhead vapor’. This sets the maximum allowable ΔP per 100 feet and maximum
velocity criteria. These two must be satisfied when deciding line diameter. If velocity
and pressure is more than the maximum criteria then increase the diameter of the
pipe. Note that as the diameter increases, the capital cost increase.
3.3.2 Two Phase Flow
A particular type of geometric distribution of the components is called Flow Pattern or
Flow Regime. Various flow maps are available to decide the flow pattern based upon
volumetric flux, momentum flux and mass velocity. So it is important to know the
flow patterns because in mass, momentum and energy transfer depend upon the
geometric distribution of the flow patterns. For example, presence of vapor in liquid
flow can sharply increase frictional pressure losses.
Type of flow regimes are as follows:
Bubble Flow
In this numerous gas bubbles are observed in the continuous liquid phase. These
bubbles vary in size and shape but are typically spherical. This pattern is observed
with at extremely low vapor quality (x<0.1) The difference between the bubble velocity
and liquid velocity is low because almost spherical bubbles are formed without much
deformation.
Slug/ Plug Flow
With increase in void fraction, gas bubbles are very close and these collide and
coalesce to form larger bubbles. Bubbles grow to size of the pipe forming a bullet like
shapes with almost hemispherical top and nearly blunt tail. These are also called
Taylor bubbles owing to instability of that name. This regime is considered a surface
tension dominated regime, because the vapor phase is impeded in the forward
direction by vapor-liquid surfaces. Another flow regime is Plug flow. In this the gas
forms elongated bubbles just like in slug flow but the diameter of these bubbles are
smaller than that of pipe.
33
Churn Flow
Increasing the velocity of flow, the structure of the bubbles becomes yet more
unstable. The flow now oscillates with the net forward motion. This region is the
intermediate stage between the slug and annular flow pattern. For small diameter
pipes, this pattern is not observed.
Annular Flow
This flow regime observed at the highest qualities, where the
vapor region is continuous in the center of the channel and the
liquid forms a film around the wall of the channel. The
interface of the liquid gas is disturbed by high frequency waves
and ripples. This flow pattern is also an inertial dominated
flow regime. This is particularly stable and is desired flow.
Mist Flow
At very high gas flow rates, the annular film is thinned by
shear of gas core on the interface until it becomes unstable
and is destroyed. In this phase the liquid is entrained as
droplets in continuous gas phase.
Stratified Flow
This occurs only in the horizontal pipes. At low liquid and gas
velocity, the two phases are completely separate in two layers.
If gas velocity increases in this regime waves are observed at
the interface of the two phases. This gives another flow regime
called Stratified-wavy flow. Further if the waves formed touch
the top of the pipe, the regime is called intermediate flow. This
can be of two types: Plug and Slug.
Example: Vertical Tube Evaporation
In a typical flow regime of the evaporator tube like in
thermosyphon reboilers. At the beginning (bottom) the flow has
bubbly flow regime with the onset of nucleate boiling. After
bubbly flow regime as flow quality increases, the flow regime
changes from slug to annular. The thin liquid film at the wall
eventually dries out and the flow enters the mist or drop
Figure 4 Boiling in Vertical tube to demonstrate various two phase flow regimes
34
regime.
Besides this case, two phase flow can be of significance like the outlet of the overhead
vapor air condenser the outlet line is to be designed to prevent slug flow. Similarly, to
minimize the slug regime in feed to fractionators control valve can be lifted to be close
to the feed inlet nozzle of column.
3.3.3 Fractionation Column
3.3.3.1 Fractionator Condensing System
The overhead condenser of the fractionator can be either partial or total condensing.
Total condensing systems have no net vapor product opposite to partial condensing
systems that have net vapor products or lighters that are to be sent to relief header.
The various condensing system that have been studied while doing this assignment
are as follows:
Water Cooler - Partial Condenser
The Oxygen Stripper Condenser in BT Fractionation Unit is of this type. The vent to
relief header is to vent out light ends. This is essential owing to the fact the aromatic
feed to this column comes from storage and enters just above the receiver. This vent
line takes into account any blanket gas leakage.
Non-Elevated Steam Generator – Total Condenser (Enclosed)
This is for condensing overhead vapor from Raffinate Column No2 in Parex Unit. In
this the steam generator is at grade. This is called enclosed due to presence of hot
vapor bypass (HVB). For total condensing system like this one, the pressure of the
column has to be maintained. The liquid in the receiver is at it bubble point. The hot
vapor at provide the requisite temperature and pressure at the surface of said bubble
point liquid. Also for every HVB setup receiver has a baffle so as to prevent liquid
surface disturbance.
Elevated Total Condenser (Enclosed)
Elevated condenser can be air cooled or water cooler depending upon the process
requirement. Air cooler overhead vapor condenser with HVB is encountered in
Depropanizer in C3 Oleflex Unit. In enclosed systems, for elevated condensers, unlike
at grade condensers, control valve is required. This is to control the column pressure
by control flow through condenser. The process outlet of condensers that are at grade
enters receiver from bottom so a liquid pocket is created that controls the column
pressure hence no need of the control valve.
35
Elevated Total Condenser (Open Vent)
Open vent implies the receiver is at float with relief header so as to control the
pressure. Also a purge line is connected with this open line so as to prevent negative
flow to relief header. This setup is used in Finishing Column in Parex Unit. For
elevated total condensing systems equalizing line is used.
Push-Pull Total Condenser
A blanketing gas flows into receiver if the receiver pressure decreases and vapors are
released to relief header if the receiver pressure increases. This setup is called Push-
Pull system. This is found at BT Column in BT Fractionation Unit.
Air Cooled followed by Water Cooler Total Condenser (Enclosed)
This is used to condense Deheptanizer overhead vapor. In this water cooler is at
grade but it may be elevated in some other case.
3.3.3.2 Fractionation Composition Control
Typical Control
In this temperature composition control adjusts the reflux and the overhead receiver
level control adjusts the net overhead product flow rate. For example, Deheptanizer
Column of Isomar Unit. For this type of control, the overhead receiver may act as a
surge drum.
Material Composition Control (Modified)
This is net overhead product is controlled by temperature composition control. The
reflux is controlled by the net overhead product flow and level control in the receiver.
This is also called Fly Wheel Control. This is used in C3-C4 Splitter in C3-C4 Oleflex
Unit.
3.3.3.3 Reboilers
Thermosyphon
The thermosyphon reboilers work on the difference in densities of the entering liquid
and exiting two phase fluid with no external requisite pressurizing. These have shell
and tube arrangement and can be horizontal or vertical.
36
Horizontal thermosyphon reboiler has process steam on shell side and heating
medium on shell side. This is better than the vertical thermosyphon reboiler when
the difference in densities between the liquid and two phase fluid is low. Also this
works better with thermal expansion. This occupies larger plot area. This can be
found in C3 Splitter in C3 Oleflex Fractionation Section.
In vertical thermosyphon reboiler the heating medium is on shell side and process on
tube side. In this plot area occupied is less and this is ideal when the lesser pressure
drop is required on the heating medium side. However there is the tube length
constraint so as to prevent swaying. Vertical thermosyphon reboiler is used to
reboiler Benzene Toluene Column with Xylene Column No2 overhead as the heating
medium.
Stabbed-in reboiler
In this the reboiler is part of the column itself. The tube bundle is inserted through a
nozzle into the column with tube length restricted by the column diameter. In this
heating medium is at tube side which is submerged in the tube wit overflow weir. In
this no external cold side piping and shell is required. Also in this more vaporization
achieved compared to thermosyphon reboilers. This can be found in Deethanizer
Stripper in Oleflex Unit.
3.3.4 Heat Exchanger
3.3.4.1 Steam Side Controls
Condensate Control
In this case, exchanger inlet is the steam directly from steam header. The heat
transferred in a heat exchanger can be controlled by a control valve in the
condensate outlet line. If the control valve is closed, the condensate flow rate
decreases. This results in flooding of heat exchanger surface. Annotate that the heat
transfer coefficient of flooded surface is lower than condensing surface. This way heat
transfer is controlled. This is most commonly used steam side control.
Steam Control
The control valve is on the steam inlet line. So the inlet stream pressure is the steam
header pressure minus the pressure drop across control valve. As the pressure
decreases, the saturated seam temperature also decreases. So the heat transfer is
controlled by controlling Logarithmic Mean Temperature Difference. This control is
used in Feed Dried Regenerant Vaporizer in Oleflex Unit. This is to prevent steam
37
entry into the regeneration process as this can freeze in the cold combined feed heat
exchanger.
3.3.4.2 Steam Condition
Desuperheater
Superheated steam can cause thermal shock and may result in leakage. Also high
heat flux in superheated steam area can cause unstable boiling of the process steam.
So to prevent this, desuperheater is provided upstream on steam side. The control is
set such that only small amount of superheat remain in the inlet steam.
3.3.4.3 Types
Electric Heater
Feed Drier Regenerant Superheater, in Oleflex Feed Drier Section, is an electric
heater. Electric heater is used to provide bone-dry service. Liquid should be
prevented from entering as it may lead to chocking problem. The water if passed on
will enter Cold Combined Feed Heat Exchanger and may freeze here.
3.4 Processes
3.4.1 Sulfolane
Sulfolane is an extractive distillation process. Feed to this unit may be from
reformate splitter. Solvent used in this process is tetrahydrothiophene 1,1-dioxide. In
this aromatics (Benzene and Toluene or Toluene and Xylene) are extracted. The
Benzene Toluene mix is sent to BT fractionation unit.
3.4.2 Benzene Toluene Fractionation
There is no inherent chemistry or chemical reaction involved in Benzene Toluene (BT)
Fractionation unit. This involves a simple fractionation with very high product purity
and recovery.
The unit separates Benzene and Toulene from the heavy aromatics. This unit uses a
dividing wall column, with internal reflux, for fractionation purpose.
38
3.4.3 Parex
In Parex unit is a continuous counter-current process for recovering para-Xylene
from the feed containing mixed Xylene isomers and ethyl benzene feed. This is an
adsorption process.
3.4.4 Isomar
In this the para depleted Xylene feed, from Parex Unit, is isomerised to get
equilibrium mixture of Xylene isomers. The ethyl benzene present in the feed can be
either converted to Xylene isomers or benzene and Xylene depending upon the
catalyst used.
3.4.5 Tatoray
This involves production of Benzene and Xylene from Toulene and C9 aromatics. The
process of conversion of Toluene to Benzene and Xylene is called Toulene
disproportionation. The process of obtaining Xylenes from Toluene and C9 aromatics
is called transalkylation. Product is split and Benzene cut (lighter) is sent to BT
Fractionation Unit. Xylene cut (heavier) is sent to Xylene Fractionation from where it
goes to Parex Unit.
3.4.6 C3 Oleflex
Oleflex is an endothermic process in which paraffin are selectively converted into
olefins by catalytic dehydrogenation process. In C3 Oleflex, feed is propane and the
end product is propylene. The process unit is divided into two sections: Fractionation
and Reactor. Fractionation section consists of the feed drier, feed guard, metal guard,
regeneration of feed drier, depropanizer, selective hydrogenation reactor, deethanizer
and C3 splitter. Reactor Section consists of reactor section, reactor effluent
compressor, reactor effluent drier, separation system (cold box), hydrogen
purification and net gas compression.
The Net Gas compression in Reactor Section is done by three reciprocating
compressors in series.
39
3.4.7 C3 C4 Oleflex
This is similar to C3 Oleflex Process. In this feed is propane and isobutane and
product is propylene and isobutylene. In fractionation section of this unit,
depropanizer is not present and a C3-C4 splitter is added to scheme. In reactor
section has a train of three reactors instead of four that is used C3 Oleflex process.
3.5 Methodology
First step involved understanding the process hydraulics. This was done via month
ling training in Hydraulics and reading of the related topics from technical manuals.
Next was to go through individual process PFDs, hydraulics from old projects and
process presentation. Then the modules were developed. Also spreadsheet for
calculating static head required for internal reflux for BT Column was propared. This
is based upon the fact that the pressure drop across control valve and the line is
fixed. Formula used is as follows:
Where,
Sp.Gr. is the specific gravity of the liquid
For the second part which involved preparation of spreadsheet, standard Unisim
simulations were used. Hydraulic for old projects were consulted to develop the
requisite spreadsheet. Then the developed spreadsheet were imported into NHP and
the errors were eliminated.
3.6 Discussion of Results
The HFD modules for each process include following information:
Line numbers
Equipment Numbers
Equivalent Line Size criteria
Line Service Code
Maximum ΔP (in psi) per 100 feet
40
Hydraulics Circuit
The spreadsheets developed include following categories:
Lines
Control Valves
Flow Devices
Vessels
Heaters
Heat Exchangers
Pumps Compressors
Nodes
Miscellaneous
For all above categories necessary information like name, number, design case,
alternate case, etc were added. Also various cases are taken into consideration while
preparation of these HFDs. For example, C3 Oleflex Fractionation Unit may have a
single Depropanizer or two Deprpanizer in parallel. Both these cases are included
into spreadsheet. So when an engineer starts with the new project, he/she can keep
the case which is required and delete the other. It should be noted here that deleting
will take lesser time than addition because for each equipment or line to be added all
information has to added.
3.6 Conclusion
This project is a part of ongoing infrastructure development.
Providing all the necessary information for carrying out hydraulic for unit is makes it
quite easy for any new engineer to go head with the process hydraulics. The HFD
modules aim at doing the same.
As for the spreadsheets that are developed are step ahead. These are be imported into
NHP and with the small necessary changes process hydraulics for any new project
can be carried out.
This whole project aims at reducing time consumed on hydraulics.
41
4 Miscellaneous Activities The project discussed so far i.e. ‘Consolidation of Hydroprocessing Vessel Design-Excel
Tools with Win254 and ‘Hydraulic Flow Diagram Modules Development’ contributed to
ninety per cent of the work done under Practice School II program. The other ten per
cent includes following short-interval and occasional projects and activities:
Prepared presentation for Two Phase Flow regimes
Finalizing HFD for Complete Saturation Process (CSP)
Participated in Beer and Peanut Relay Race. Our team won in all women
category
Preparation of Heat Integration Diagram for Aromatic Complex
Participated in Annual Day Celebration
Finalized HFD for Huels Selective Hydrogenation Process (SHP)
Read about Merox Process
42
5 Appendix
5.1 Appendix A
A Snap shot of HFD for Benzene Toluene Unit is as follows:
43
5.2 Appendix B
A snap shot of spread sheet prepared for C3 Oleflex Fractionation Unit:
44
6 Glossary
Alkenes
Alkenes are mono-olefins with the general formula CnH2n and contain only one
carbon-carbon double bond in the chain. Olefins are usually formed by thermal and
catalytic cracking and rarely occur naturally in unprocessed crude oil.
Aromatics
Aromatics are unsaturated ring-type (cyclic) compounds which react readily because
they have carbon atoms that are deficient in hydrogen. All aromatics have at least
one benzene ring (a single-ring compound characterized by three double bonds
alternating with three single bonds between six carbon atoms) as part of their
molecular structure.
Coke and Asphalt
Coke is almost pure carbon with a variety of uses from electrodes to charcoal
briquets. Asphalt, used for roads and roofing materials, must be inert to most
chemicals and weather conditions.
Dienes and Alkynes
Dienes, also known as diolefins, have two carbon-carbon double bonds. The alkynes,
another class of unsaturated hydrocarbons, have a carbon-carbon triple bond within
the molecule. Both these series of hydrocarbons have the general formula CnH2n-2.
Distillate Fuels
Diesel fuels and domestic heating oils have boiling ranges of about 400°-700° F. The
desirable qualities required for distillate fuels include controlled flash and pour
points, clean burning, no deposit formation in storage tanks, and a proper diesel fuel
cetane rating for good starting and combustion.
Gasoline
The most important refinery product is motor gasoline, a blend of hydrocarbons with
boiling ranges from ambient temperatures to about 400°F. The important qualities for
gasoline are octane number (antiknock), volatility (starting and vapor lock), and vapor
pressure (environmental control). Additives are often used to enhance performance
and provide protection against oxidation and rust formation.
45
Hydraulic Flow Diagram
Hydraulics Flow Diagram (HFD) is the process flow diagram with hydraulic circuits
marked on it.
Kerosene
Kerosene is a refined middle-distillate petroleum product that finds considerable use
as a jet fuel and around the world in cooking and space heating. When used as a jet
fuel, some of the critical qualities are freeze point, flash point, and smoke point.
Commercial jet fuel has a boiling range of about 375°-525° F, and military jet fuel
130°-550° F. Kerosene, with less-critical specifications, is used for lighting, heating,
solvents, and blending into diesel fuel.
Liquified Petroleum Gas (LPG)
LPG, which consists principally of propane and butane, is produced for use as fuel
and is an intermediate material in the manufacture of petrochemicals. The important
specifications for proper performance include vapor pressure and control of
contaminants.
Lubricants
Special refining processes produce lubricating oil base stocks. Additives such as
demulsifiers, antioxidants, and viscosity improvers are blended into the base stocks
to provide the characteristics required for motor oils, industrial greases, lubricants,
and cutting oils. The most critical quality for lubricating-oil base stock is a high
viscosity index, which provides for greater consistency under varying temperatures.
Naphthalene
Naphthenes are fused double-ring aromatic compounds. The most complex
aromatics, poly-nuclears (three or more fused aromatic rings), are found in heavier
fractions of crude oil.
Naphthenes
Naphthenes are saturated hydrocarbon groupings with the general formula CnH2n,
arranged in the form of closed rings (cyclic) and found in all fractions of crude oil
except the very lightest. Single-ring naphthenes (mono-cyclo-paraffins) with five and
six carbon atoms predominate, with two-ring naphthenes (di-cyclo-paraffins) found in
the heavier ends of naphtha.
Paraffins
46
The paraffinic series of hydrocarbon compounds found in crude oil have the general
formula CnH2n+2 and can be either straight chains (normal) or branched chains
(isomers) of carbon atoms. The lighter, straight-chain paraffin molecules are found in
gases and paraffin waxes. The branched-chain (isomer) paraffins are usually found in
heavier fractions of crude oil and have higher octane numbers than normal paraffins.
These compounds are saturated hydrocarbons, with all carbon bonds satisfied, that
is, the hydrocarbon chain carries the full complement of hydrogen atoms.
Petrochemicals
Many products derived from crude oil refining, such as ethylene, propylene, butylene,
and isobutylene, are primarily intended for use as petrochemical feedstock in the
production of plastics, synthetic fibers, synthetic rubbers, and other products.
Process Flow Diagram
Process Flow Diagram (PFD) is a diagram commonly used in chemical and process
engineering to indicate the general flow of plant processes and equipment. The PFD
displays the relationship between major equipment of a plant facility and does not
show minor details such as piping details and designations.
Residual Fuels
Many marine vessels, power plants, commercial buildings and industrial facilities use
residual fuels or combinations of residual and distillate fuels for heating and
processing. The two most critical specifications of residual fuels are viscosity and low
sulfur content for environmental control.
47
7 References Technical manuals and presentations
Buongiorno, Jacopo Notes on Two‐Phase Flow, Boiling Heat Transfer, and
Boiling Crises in PWRs and BWRs MIT Department of Nuclear Science and
Engineering. http://ocw.mit.edu/courses/nuclear-engineering/22-06-
engineering-of-nuclear-systems-fall-2010/lectures-and-
readings/MIT22_06F10_lec13.pdf
https://www.ideals.illinois.edu/bitstream/handle/2142/12908/TR248.pdf?se
quence=2
http://www.wlv.com/products/databook/db3/data/db3ch12.pdf
Flow patterns http://authors.library.caltech.edu/25021/1/chap7.pdf.
Overton, Steve and Jonathon Bell Vessel design, Suncombe Ltd.
http://www.suncombe.com/Brochures/Vessel%20Design%20Overview.pdf
Cusack, R. Rethink your liquid-liquid separations, Koch-Glisch, Wichita, Kansas,
June 2009, pg53-60. http://www.koch-glitsch.com/Document%20Library/Liq-
liq_Separations_HP_June09.pdf
Suppes, G. J. Heuristics in Chemical Engineering, Butterworth-Heinemann, Boston,
Feb 2002. http://people.clarkson.edu/~wwilcox/Design/heurist.pdf
http://www.red-bag.com/engineering-guides/249-bn-eg-ue109-guide-for-vessel-
sizing.html
Smith, Peter Basic Process Design Engineering for Non Process Engineers, PHD
Online, 2012. http://www.pdhonline.org/courses/m182/Process%20Design%20P-
001.pdf
