UNIVERSITY OF DAR-ES-SALAAM
COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF CHEMICAL AND MINING ENGINEERING
PRACTICAL TRAINING REPORT
[PT3]
2011/ 2012.
COMPANY: PAN AFRICAN ENERGY TANZANIA,(PAT).
PROJECT TITLE: MONO ETHYLENE GLYCOL TRAINS EFFICIENCY
EVALUATION.
DEGREE PROGRAMME: CHEMICAL AND PROCESSING ENGINEERING
STUDENT NAME: ELVIS VALENTINE
REGISTRATION NUMBER: 2008-04- 03459
INDUSTRIAL TRAINING OFFICER: ENG.JAMES MUGENYI
TRAINING SUPERVISOR: BAKAR FRANCIS
DURATION: 25TH
JULY-30TH
SEPT [10 WEEKS].
i
ACKNOWLEDGEMENT:
I would like to thank Pan African Energy administration and the whole management for
granting me the chance to conduct my practical training in the company, because for me
it was a golden chance that I couldn’t dare to lose. My ten weeks at PAT have been the
time to learn, with a lot of challenges that I am sure have helped me to expand my
knowledge to a large extent. All these couldn’t happen without having cooperative and
patient people who could even sacrifice their time to share with me, whatever information
I needed. Below are the people whom wherever I talk about my success, I would have to
remember them concerning their contributions and support which they gave me.
First I would like to express my gratitude to all members in all departments of Pan
African Energy Tanzania. I did appreciate your cooperation, thanks a lot.
My special thanks should go to Eng. James Mughenyi and Mr. Onestus .E.Kajumulo , my
Industrial training officers who have been very kind and cooperative;
Actually They were my stabilizers in the plant, guiding me as well as correcting me
wherever I go wrong. Truthfully these were the best thing I needed as a student.
Pan African Energy Tanzania has got a lot of employees and every one used his/ her own
position to support me. I just want to say thanks to everybody, may God bless you all.
Finally I would like to thank my University Supervisor Eng. Bakar Francis from
department of Chemical and Mining Engineering, University of Dar-es-salaam for his
valuable suggestion and consultation on my training as well as my report.
ii
ABSTRACT:
The aim of this report is to give the explanation of the natural gas production processes
at Pan African Energy Tanzania in brief as well as the explanation of the project part
beginning from the influencing factor(aim) of carrying out the project ,theory till its
conclusion.
The report consists of two major parts these are:
Processing part
Project part
The processing part consists of two major sub parts these are processing and distribution
processes.
The project part it’s all about the solution to mono ethylene glycol loss facing the
company production processes especially in natural gas dehydration. Mono ethylene
glycol reclamation unit efficiency fluctuation seems to be the major causes and this is due
to operate the plant under overloaded situation, maintaining system operating conditions
(i.e re-boiler temperature and glycol concentration to specific and designed conditions)
even ensuring proper retention time for glycol separation(using designed tank) the glycol
loss can be reduced to 90% which will rescue the company from high/overspending
natural gas dehydration operational cost.
The methodology used was the analysis of meg quality and properties, performance of
each units operation in meg trains and vessels capacity based on data recorded during
normal/designed against current overloaded situation.
The result obtained for Meg concentration of the data analyzed were under specifications
for normal operation, and out of specification (for about 30-34% rich meg
concentration)for maximum operations even under the current overloaded situation. Unit
operations efficiency ranging in 80-90% for normal operations 60-70% for maximum
and below 60% for overloaded conditions.
During normal, maximum even current situation vessels capacity were the same that
means that they are overloaded.
iii
Table of Contents
ACKNOWLEDGEMENT: ...........................................................................................................i
ABSTRACT: ..............................................................................................................................ii
INTRODUCTION: ..................................................................................................................... 1
HISTORICAL BACK GROUND: ............................................................................................... 3
MISSION OF THE COMPANY: ................................................................................................ 3
VISSION OF THE COMPANY : ................................................................................................ 4
POLICY OF THE COMPANY: .................................................................................................. 5
COMPANY ORGANIZATION STRUCTURE. ...................................................................... 5
NATURAL GAS PROCESSING: ............................................................................................... 7
Background: ............................................................................................................................ 7
History: ................................................................................................................................... 7
Natural gas raw materials: ....................................................................................................... 8
Natural gas composition: ..................................................................................................... 9
The manufacturing process: ................................................................................................... 10
Extraction: ......................................................................................................................... 10
Process description: ............................................................................................................... 11
NATURAL GAS TRANSPORTATION: .................................................................................. 13
Natural gas pipeline ............................................................................................................... 13
NATURAL GAS DISTRIBUTION: .......................................................................................... 14
Natural gas safety in distribution: .......................................................................................... 14
THE FUTURE OF NATURAL GAS: ....................................................................................... 15
OTHER PROCESSES ACCOMPANY THE PRODUCTION: .................................................. 16
Plant Meg reclamation and circulation system: ...................................................................... 16
Plant Condensate processing: ................................................................................................ 17
Condensate transportation:................................................................................................. 18
Plant Produced water handling systems: ................................................................................ 19
PLANT UTILITIES: ................................................................................................................. 20
Water plant: .......................................................................................................................... 20
Instrument Air Plant: ............................................................................................................. 20
Electricity production: ........................................................................................................... 21
Safety Systems: ..................................................................................................................... 21
iv
PROJECT ................................................................................................................................. 22
INTRODUCTION .................................................................................................................... 23
STATEMENT OF THE PROBLEM: ...................................................................................... 25
OBJECTIVE: ............................................................................................................................ 26
SIGNIFICANCE OF THE STUDY. ......................................................................................... 26
LITERATURE REVIEW: ......................................................................................................... 27
Process description: ............................................................................................................... 27
Meg trains efficiency: ............................................................................................................ 29
Mono ethylene glycol chemistry: ........................................................................................... 34
i)antifreeze chemistry ........................................................................................................ 35
ii)hydrate inhibition chemistry: .......................................................................................... 38
METHODOLOGY:................................................................................................................... 40
Equipment used ................................................................................................................. 40
Experimental part: ................................................................................................................. 40
RESULTS, CALCULATION AND DISCUSION: .................................................................... 42
Experimental results: ............................................................................................................. 42
Vessels capacity evaluation: .................................................................................................. 54
Problems facing the system caused by plant overloading: ...................................................... 58
Current efforts made to solve the current system problems:.................................................... 63
OVERVIEW: ............................................................................................................................ 65
CONCLUSSION AND RECOMMENDATION: ....................................................................... 66
Recommendation: ................................................................................................................. 66
Conclusion: ........................................................................................................................... 67
REFERENCES: ........................................................................................................................ 68
LIST OF ABBREVIATIONS: ................................................................................................... 69
v
List of figures:
Figure 1;Company organisation structure .................................................................................... 6
Figure 2:General Process overview............................................................................................ 11
Figure 3:Gas Transportation System .......................................................................................... 13
Figure 4:Meg regeneration Unit ................................................................................................. 16
Figure 5:Condensate Processing overview ................................................................................. 17
Figure 6:produced water handling Overview ............................................................................. 19
Figure 7:Plant Utilities overview ............................................................................................... 20
Figure 8:Dew point Control Train overview .............................................................................. 24
Figure 9:Meg regeneration Unit ................................................................................................. 28
Figure 10:Graph of meg freezing point vs concentration ............................................................ 36
Figure 11:graph showing temperature in meg lab test carried ..................................................... 44
Figure 12:Graph showing lean glycol water ratio vs time ........................................................... 45
Figure 13:laboratory rich glycol vs time .................................................................................... 47
Figure 14:monthly average properties of lean glycol train 2 ....................................................... 48
Figure 15:monthly average properties of lean glycol .................................................................. 49
List of Tables:
Table 1;natural gas composition ................................................................................................ 10
Table 2:plant specifications according to design ........................................................................ 32
Table 3:Ethylene glycol concentration vs temperature ............................................................... 35
Table 4:Boiling point vs concentration ...................................................................................... 37
Table 5:Meg boiling point Vs concentration .............................................................................. 38
Table 6:lean glycol properties in train1. ..................................................................................... 43
Table 7: monthly properties of rich glycol in train 1 .................................................................. 46
Table 8:monthly average properties of rich glycol ..................................................................... 50
Table 9:monthly average properties of rich glycol 2................................................................... 51
Table 10:monthly data on dew point control trains ..................................................................... 51
Table 11:monthly average data on dpc 2 .................................................................................... 52
Table 12abbreviations ............................................................................................................... 70
1
INTRODUCTION:
Pan African Energy Tanzania is the company whose principal activities is to carry out the
production, distribution and sales of the natural gas in Tanzania. It operates gas wells,
processing plant in Songosongo island within kilwa district in Lindi region and the whole
downstream gas distribution network to consumers here in Dar es Salaam.
The company also owns and manages Compressed Natural Gas stations (CNG) for gas
storage and transportation to the non-pipelined areas. Also company work with Lootah
BC Gas as a sub-contract in downstream networking operation and maintenance for
efficiently supply of natural gas to consumers. The company distribute natural gas to
residential houses, industries and power plants for electricity generation.
PAT daily activities are well organized and this is actually what contributes much to the
great achievement. The company has got a lot of departments and each department has
got its own function or contribution to the plant’s development. Below are the
departments found in this company and their functions.
The logistic department this is one of the very important department since it coordinate
transportations, maintain company facilities, order and supply equipments and goods for
plant production process.
Health and safety is department which ensures safely working condition of workers and
their environment during normal operation of gas processing and distribution.
Human resources is a department which manage human resources and ensuring good
working and social interaction among workers.
Finance department this is actually concerned with financing all companies needs to
assist all activities in the whole production, processing and distribution of natural gas.
Operation department this is one of the department found in any processing industry, the
main function of this is to give support to the production process by providing utilities
and carry out maintenance to the productive equipment whenever necessary or according
to the schedule. To ensure all these the department is divided into several sub sections
these are:
Utilities section:
This section comprises with Instrument and utility air system, meg regeneration units,
portable water and sea water system. This section is for preparation of plant
usefulness/utilities for natural gas processing.
2
Wellheads section:
Wellhead section is comprised of three onshore wells and three offshore wells.Two
onshore wells ss10 and ss4 are commingled to 4” pipeline that supply to the inlet
manifold and one of offshore(ss5) currently is not in use due to corrosion in its
tubing. All of these wells flow are metered and gathered in inlet manifold for plant
input.
Gas Processing Plant:
Processing plant consist of inlet manifold and pig launching, high pressure and
temperature separation (inlet separator),dehydration units ,sales gas metering skid,
produced water handling unit condensate storage and flare systems.
3
HISTORICAL BACK GROUND:
Pan African Energy Tanzania (PAT) is a subsidiary of Orca Exploration Group, Inc. (the Group),
an international public company engaged in the exploration and production and marketing of
natural gas. The Group is listed on the Toronto Venture Exchange (TSXV) and previously
operates as East Coast Energy Corporation, originally a subsidiary of Pan Ocean Energy
Corporation that was in 2004 distributed to shareholders and listed separately before changing its
name to Orca Exploration Group Inc. in 2006.
MISSION OF THE COMPANY:
Pan African Energy Tanzania (PAT’s) Mission is to become a leading integrated energy
company. In its quest to achieve this mission, the company will:
Make a positive contribution to the people, Government and economy of Tanzania
through provision of efficient, reliable, high quality and safe gas supply services.
Provide a clean energy source with no significant environmental damage.
Engage our stakeholders with respect, trust and understanding to progress solutions that
benefit all parties in a timely manner.
Support social developments to ensure that quality of living is improved.
Manage our workforce in a manner which enhances individual performance, develops
staff members, sets a culture of co-operation, motivation and trust, and delivers reliable
results.
Protect and enhance shareholder interests through delivery of financial performance
leading to increased shareholder value or financial returns.
Attract investment in further programmes by optimizing the balance between Tanzania’s
needs and investor requirements within a competitive global market.
Explore and develop further the country’s energy resources in a sustainable manner by
identifying and progressing new energy opportunities.
4
VISSION OF THE COMPANY :
The Company endeavors at all times to provide a working environment that will permit
employees to achieve the highest level of individual and company performance. It seeks at all
times to:
Provide fair and equitable treatment of employees;
Encourage and provide opportunities for self-development and advancement;
Discourage, in any form, discrimination in employment because of race, color, religion,
sex, nationality, national origin, tribe, age or disability, social origin, political opinion,
gender, pregnancy, marital status even HIV/AIDS.
Encourage and provide opportunity for staff communication and interaction in personnel
issues.
5
POLICY OF THE COMPANY:
The Company and specifically its Board of Directors and management team has a primary and
continuous commitment to protect the environment, the health, safety and security of its
Employees and of all personnel involved in or affected by its activities. This is achieved through
the active implementation and continual monitoring of its HS&E Policy, which sets specific
standards and targets, which are mandatory and applicable to all locations and activities. Full
details are contained in the Company Safety and Environmental Management System (SEMS).
Every Employee and contractor has a responsibility to familiarize themselves with the policies
and procedures contained therein.
The board will regularly review HS& activities and ensure that targets for continuous
improvement are maintained.
As part of their key accountabilities, the executive team will ensure that an appropriate HS&E
organization is maintained with clear lines of responsibility. In particular, the management team
will make available the necessary fund and resources for the effective management of HS&E
activities are not compromised in any, shape or form in the pursuit of business objective.
COMPANY ORGANIZATION STRUCTURE.
PAT comprises of different departments and section .The departments includes Drilling , Health,
safety and the environment , Human resource, Finance and Operation. The different sections are
function support to the Departments, these includes distribution manager, production
superintendent, production engineer, upstream assert manager, financial controller.
6
General
manager
HSE manager
Deputy
general
manager
Upstream
manager
Project
manager
Head of
production
Financial
controller
Drilling
manager
Production
engineer
Ssi operation
Production
superintendant
Distribution
manager
Function
support
Finance
department
Drilling
operation
Us ssi
operation
Op main
coordinator
Ds dar
operations
Figure 1;Company organisation structure
7
MAIN REPORT:
PART ONE
NATURAL GAS PROCESSING:
Background:
Natural gas is a mixture of combustible gases formed underground by the decomposition of
organic materials in plant and animal. It is usually found in areas where oil is present, although
there are several large underground reservoirs of natural gas where there is little or no oil.
Natural gas is widely used for electric power generation, as well as for a variety of industrial
applications.
History:
Natural gas was known to early man in the form of seepages from rocks and springs. Sometimes,
lightning or other sources of ignition would cause these gas seepages to burn, giving rise to
stories of fire issuing from the ground. In about 900 B.C. natural gas was drawn from wells in
China. The gas was burned, and the heat was used to evaporate seawater in order to produce salt.
By the first century, the Chinese had developed more advanced techniques for tapping
underground reservoirs of natural gas, which allowed them to drill wells as deep as 4,800 ft
(1,460 m) in soft soil. They used metal drilling bits inserted through sections of hollowed-out
bamboo pipes to reach the gas and bring it to the surface.
The Romans also knew about natural gas, and Julius Caesar was supposed to have witnessed a
"burning spring" near Grenoble, France. Religious temples in early Russia were built around
places where burning natural gas seepages formed "eternal flames."
In the United States, the first intentional use of natural gas occurred in 1821 when William Hart
drilled a well to tap a shallow gas pocket along the bank of Canadaway Creek near Fredonia,
New York. He piped the gas through hollowed logs to a nearby building where he burned it for
illumination. In 1865, the Fredonia Gas, Light, and Waterworks Company became the first
8
natural gas company in the United States. The first long-distance gas pipeline ran 25 mi (40 km)
from a gas field to Rochester, New York, in 1872. It too used hollowed logs for pipes. The
development of the Bunsen burner by Robert Bunsen in 1885 led to an interest in using natural
gas as a source of heating and cooking, in addition to its use for lighting. In 1891, a high-
pressure gas deposit was tapped in central Indiana, and a 120 mi (192 km) pipeline was built to
bring the gas to Chicago, Illinois.
Despite these early efforts, the lack of a good distribution system for natural gas limited its use to
local areas where the gas was found. Most of the gas that came to the surface as part of oil
drilling in more remote areas was simply vented to the atmosphere or burned off in giant flares
that illuminated the oil fields day and night. By the 1910s, oil companies realized that this
practice was costing them potential profits and they began an aggressive program to install gas
pipelines to large metropolitan areas across the United States. It wasn't until after World War II
that this pipeline program had reached enough cities and towns to make natural gas an attractive
alternative to electricity and coal.
By 2000, there were over 600 natural gas processing plants in the United States connected to
more than 300,000 mi (480,000 km) of main transportation pipelines. Worldwide, there are also
significant deposits of natural gas in the former Soviet Union, Canada, China, and the Arabian
Gulf countries of the Middle East.
Natural gas raw materials:
Raw natural gas is composed of several gases. The main component is methane. Other
components include ethane, propane, butane, and many other combustible hydrocarbons. Raw
natural gas may also contain water vapor, hydrogen sulfide, carbon dioxide, nitrogen, and
helium.
During processing, many of these components may be removed. Some such as ethane, propane
and butane are completely removed processed and transported by TPDC loading ships. Other
components such as water vapor and carbon dioxide are removed to improve the quality of the
natural gas so as to make it easier to move the gas over great distances through pipelines to Dar
es salaam.
The resulting processed natural gas contains mostly methane , although there is no such thing as
a "typical" natural gas. Certain other components may be added to the processed gas to give it
special qualities. A chemical known as mercaptan is added to give the gas a distinctive odor that
warns people encase of a pipeline leak.
9
Natural gas composition:
The natural gas used by consumers is composed almost entirely of methane. However, natural
gas found at the wellhead, although still composed primarily of methane, is by no means as pure.
Raw natural gas comes from three types of wells: oil wells, gas wells, and condensate wells.
Natural gas that comes from oil wells is typically termed 'associated gas'. This gas can exist
separate from oil in the formation (free gas), or dissolved in the crude oil (dissolved gas). Natural
gas from gas and condensate wells, in which there is little or no crude oil, is termed 'none
associated gas'. Gas wells typically produce raw natural gas by itself, while condensate wells
produce free natural gas along with a semi-liquid hydrocarbon condensate. Whatever the source
of the natural gas, once separated from crude oil (if present) it commonly exists in mixtures with
other hydrocarbons; principally ethane, propane, butane, and pentanes. In addition, raw natural
gas contains water vapor, nitrogen, and other compounds.
Gas Composition
C1 C2 C3 i-C4 n-C4 i-C5 n-C5 neo-
C5
C6+ N2 CO2 H2O
Mole
%
Mole
%
Mole
%
Mole
%
Mole
%
Mole
%
Mole
%
Mole
%
Mole
%
Mole
%
Mole
%
ppm
97.21
46
0.990
6
0.289
1
0.064
1
0.080
9
0.028
0
0.024
3
0.000
0
0.132
6
0.734
5
0.441
3
4.000
0
97.20
80
0.991
3
0.289
5
0.064
6
0.081
1
0.028
5
0.025
3
0.000
0
0.136
3
0.734
7
0.440
7
4.000
0
10
97.21
20
0.991
0
0.289
0
0.064
5
0.081
0
0.028
2
0.023
8
0.000
0
0.134
6
0.734
5
0.441
4
4.000
0
97.20
90
0.991
2
0.289
7
0.064
6
0.081
1
0.027
1
0.024
6
0.000
0
0.137
2
0.734
4
0.441
1
4.000
0
97.20
74
0.991
2
0.289
5
0.064
4
0.081
0
0.028
0
0.024
7
0.000
0
0.136
7
0.734
8
0.442
3
4.000
0
97.20
83
0.990
9
0.288
8
0.064
8
0.080
9
0.029
1
0.024
6
0.000
0
0.134
9
0.734
1
0.443
6
4.000
0
97.20
72
0.990
9
0.289
4
0.064
2
0.081
0
0.028
2
0.024
8
0.000
0
0.137
6
0.733
9
0.442
8
4.000
0
Table 1;natural gas composition
The manufacturing process:
The methods used to extract, process, transport, store, and distribute natural gas depend on the
location and composition of the raw gas and the location and application of the gas by the end
users. Here is a typical sequence of operations used to produce natural gas for Tanzania power
plants, industries and domestic demand.
Extraction:
The Songo songo underground natural gas reservoirs are under enough internal pressure that the
gas can flow up the well and reach Earth's surface without additional help. Through wells
tubings the gas flows upward to the surface. When the raw natural gas reaches the surface, it is
carefully controlled by wellhead Christmas tree valves and is finally piped to a gas processing
plant. About five wells current feed into the Songo songo processing plant.
11
Process description:
Gas processing:
wellhead
WATER
STORAGE
TANK
Water disposal
to sea
Gas
boot
To jetty for
export
Cond pre heater
Cond heater &
flash tank
Cold separator
Glycol gen
Sales gas
flare
Fuel gas
Pump
G/G h.e
Skimmer
C.P.I
C.D.D header
SLOP
OIL
TANK
OIL
STORAGE
TANK
CONDENSATE
TANKS
CONDENSATE
TANKS
FILTER
Pump
pump
pump
pump
pump
J.t valve
LV
LV
LV
LV
XV
V-4
SDV
LV
LV
LV
LV
Plant bypass
SDV
test separator
P-4
P-10
P-11 P-12
P-17
P-18
P-24 P-25P-26
P-28P-30
flare
P-31 P-32
P-33 P-39
P-40
P-41
P-45
inlet separator P-50
P-51P-52P-53P-54
P-55
LV
P-58 P-60 P-61 P-63
P-65
P-67 P-68 P-69
P-71
P-72 P-76P-77
P-78
P-83
P-87P-88
P-89
P-90
P-93
P-94
P-95
P-96
P-99
P-103
P-104
P-105
VENT
P-106
P-107
P-108
P-109P-110
P-111 P-112
P-113 P-114
P-115
P-116
P-118
P-116
P-119P-120
P-121
P-122
P-123
P-124
P-125
P-128P-130
P-131
P-132
P-24
P-140
P-141
P-142
P-143 P-24
FL
Figure 2:General Process overview
With the assistance of Christmas trees in well heads the well fluids from the two offshore wells
SS-7 and SS-9 and three onshore Wells SS-3,SS-10 and SS-4 injected with mixture of
corrosion inhibitor and water clarifier are transported in two individual 6” and two
individual 4” buried flow lines respectively to the gas plant inlet skid where they tie into their
individual inlet flow control valves. The flow lines then run to the gas plant inlet
metering and manifold skid where each well’s production is measured in a meter run.
The inlet manifold consists of a 10” HP production header and a 10” test header for gas stream
mixing which is done purposely to allow set up of production “well sets “so that for a given
production level, the best reservoir utilization, well flow composition can be selected from the
available wells. The gas from test header flows into the test separator. With valves assistance
12
provided, the inlet manifold permits any or all producing wells to be diverted to test
separator.
Test separator is a three-phase separator complete with a boot. Accounting type gas (senior
orifice type fittings) and liquid metering (turbine flow meter) is provided in the outlet piping
from the vessel to allow for periodic well testing. The gas stream flows from the test separator to
the inlet separator (V-110) gas outlet line. The hydrocarbon liquid stream is metered and dumped
under level control to the condensate flash tank. Produced water separated in the boot is metered
and dumped under level control to the produced water handling system.
The gas from HP production header flows into a three phase Inlet Separator for separation. Inlet
separator is a three-phase (gas, condensate and water) separator complete with a boot. The vessel
is sized to handle any liquid slugs from the well flow lines. A high-level dump system is
provided such that in the event of a large slug the liquids are automatically dumped to the closed
drain drum. Hydrocarbon liquids are separated from the gas and water behind a weir in
the main vessel and are dumped under level control to the condensate flash tank.
Produced water is separated in the boot and is normally dumped under level control to the
produced water handling system.
The gas from test and production separators is commingled and then the stream is split to enter
two dew point control trains. The gas first enters the tube side of the gas-gas exchanger where it
is pre-cooled by counter-current heat exchange with the outgoing dry sales gas. Lean glycol
solution is sprayed onto the inlet tube sheet of each exchanger to absorb water and prevent the
formation of hydrates. The gas from heat exchangers is further cooled by pressure drop
across the Joule Thomson valves, upstream of cold separators. During this cooling process,
hydrocarbon liquids are condensed. Cold separators are three phase Separators where gas,
condensate and rich glycol are separated. The separated condensate flows under level control to
the condensate stabilization unit and rich glycol flows under level control to the Glycol
Regeneration units for re-concentration prior to re-injection at the gas-gas exchangers. The
separated dry gas from the cold separator flows through the shell side of the gas- gas exchanger
and leaves the plant as sales gas. The treated gas streams from both the dew point control trains
are commingled. A portion of this gas is sent to the fuel gas system for make-up requirements
and the remaining dry gas flows to the marine pipeline and onto the mainland. This fuel gas is
metered, heated across Fuel Gas Heater and let down across a Pressure control valve to about
350 kPag and 30°C before entering the Low pressure fuel gas scrubber. The sales gas is metered
in a metering unit (ultrasonic sales gas meter) and odorized prior to its entering the 12” marine
pipeline for gas transportation to Dar es salaam.
13
NATURAL GAS TRANSPORTATION:
Figure 3:Gas Transportation System
Natural gas pipeline
Fundamentally, the best and efficient method of gas transport worldwide is through pipeline
network. Mercaptan is injected into the processed natural gas to give it a distinctive warning
odor, and then gas is piped in 12”marine pipeline to Somanga funga(25kms) where is then
connected to another 16”onland pipeline from Somanga funga to Dar es salaam(about
225kms).The gas leaves processing plant with pressure about 87bars transported through
pipeline by pressure difference mechanism. After reaching Dar es salaam the gas is then
distributed to consumers through pressure reduction stations for monitoring and pressure
controlling.
14
NATURAL GAS DISTRIBUTION:
Through these pipelines that bring the gas into Dar es salaam city where it is to be used. The
pressure is reduced to below 68-78bars, and the gas is distributed in underground pipelines that
run throughout Dar es salaam industrial customers and power plants. Before the gas is piped to
customers it must pass through two city gates(ubungo and gongolamboto pressure reduction
stations) where the pressure is further reduced to about 6-7bars for industrial customers. In big
Power plants no need for pressure reduction. For customers in which the distribution pipeline
doesn’t reach to their area (like movenpick hotel,mickocheni residential houses and some of
industries)the compression station in ubungo compress the gas filling to trailers for transportation
to those customers.
Natural gas safety in distribution:
Natural gas burns readily in air and can explode violently if a large quantity is suddenly ignited.
Because natural gas is odorless, foul-smelling mercaptan is added to the gas so that even a small
leak will be immediately noticeable. To protect high-pressure underground gas pipelines, a bright
yellow plastic tape is buried in the ground a few feet above the pipeline to warn people who
might be digging in the area. Warning signs are also placed at ground level along the entire
length of the pipeline as an additional precaution.
15
THE FUTURE OF NATURAL GAS:
Because natural gas is clean burning, it is being considered as an alternative fuel for motor
vehicles. About 30 car Compressed natural gas (CNG) cars and trucks are already on the road
here in Dar es salaam. Many Companies using industrial processes that require high
temperatures are also turning to natural gas instead of other fuels in order to reduce the air
pollution emitted by their plants and overcoming energy costs even being ensured of continuous
energy supply in the power crisis situation. This includes companies involved in manufacturing
steel, glass, ceramics, cement, paper, chemicals, aluminum, and processed foods here in Dar es
salaam.
16
OTHER PROCESSES ACCOMPANY THE PRODUCTION:
Plant Meg reclamation and circulation system:
FUEL GAS
F L
FILTERSURGE DRUM
RE BOILER
LV
PUMP
R.CONDENSER
pckg
P-11
P-15
P-17
P-19
P-21
CLOSED DRAIN DRUM
FLUSH VESSEL
P-22
P-34
P-40
P-43
P-44
P-46
P-48
P-50
BURNER
P-51
LEAN GLYCOL
P-57
P-58
P-59
G/G EXCHANGER
P-62
FILTER
P-65
P-66
COLD SEPARATOR
RICH GLYCOL
Figure 4:Meg regeneration Unit
The rich glycol from the cold separators enters the reflux coils above the packing in the still
columns of the ethylene glycol Re-boilers, where self refluxing occurs. The rich glycol is then
passed through integral lean / rich glycol coils in the surge tank section of the Ethylene Glycol
Re-boilers. After being preheated by the lean Ethylene Glycol in the accumulator, the rich glycol
stream flows to the Glycol Flash tanks where any free gases that exist are flashed off and sent to
flare. Any liquid Hydrocarbon that have been carried over to the flash tank is also removed
utilizing the Hydrocarbon skimmer connection. Glycol from flash tank flows under level
control to the top of the packed section in the glycol still column through Particulate
filters and carbon filters. In the glycol still column, water is stripped out of the rich MEG as it
flows downward through the packed section consisting of PALL rings, counter-current to the
steam that is generated in the Ethylene Glycol Re-boilers. The steam is discharged to the Low
Pressure flare header at the top of the still column. Once the desired concentration
(temperature) is achieved in the Ethylene Glycol Re-boilers, lean MEG flows by gravity to the
17
Glycol surge tank (integral with the glycol re-concentrator) where it is cooled by heat
exchange with the rich MEG flowing through the integral lean/rich glycol coils. From the
surge tank, the glycol flows to the suction of the glycol pumps, where it is pressurized for re-
injection in the gas/gas exchangers. The lean glycol concentration leaving the EG
regeneration skids is maintained at approximately 80% as glycol concentrations outside of these
ranges may lead to crystallization at low temperatures, high plant pressure drops, and
ultimately freezing – off of the Gas/Gas Heat exchangers.
Plant Condensate processing:
CONDENSATE
STORAGE TANK
LP FUEL GAS
BLANKETING
VENT TO ATM
WATER-PWS
P 701 & 703
P 710
P 700
SLOP OIL
TANK
EXPORT
TANKERS
BURNERS
V-5
Figure 5:Condensate Processing overview
The hydrocarbon liquids recovered from the dew point control unit cold separators and
test / inlet separator are mixed and preheated in the Condensate pre-heater. The pre-
heated condensate is let down in a pressure control valve to about 350 kPag prior to introduction
into the Condensate Flash tank. Final stabilization occurs in flash tank, by ensuring that the
condensate remains at a boiling temperature of 71°C. The temperature is maintained by an
18
Electric Element. The stabilized condensate from the flash tank flows under level control and is
passed through the shell side of condensate pre heater where it is cooled. From Condensate pre-
heater, the condensate flows to the Gas Boot, for further degassing and finally to storage
for further export. Condensate from gas boot is transferred to the Condensate Storage
Tanks by condensate transfer pumps. Export Pump, transfers the condensate from the
condensate storage tank to the Jetty through a condensate pipeline (6”). The export condensate
flow is measured in a turbine flow meter. Excess Condensate produced is routed to a liquid
burner for disposal through Condensate Pump. The vapors from condensate flash tank exit
under pressure control to the Low Pressure Fuel gas Scrubber. The scrubbed gas from gas
scrubber then enters Low Pressure Fuel gas filters for removal of any particles and liquid
components. Outlet dry gas from the filter is used as plant fuel gas. The vapors from gas
boot are vented to atmosphere under pressure control.
Condensate transportation:
As soon as the amount of condensate in the condensate storage tank is found sufficient, then it is
the right time for empting the tank to allow continuous gas production. The RVP test is
conducted so as to determine the type of the ship’s storage tank to come. After the ship is at the
jet, the condensate transfer pipe is connected to the ship and the condensate export pump is
turned on. There-after, the ship leaves with the condensate to Dar es Salaam.
19
Plant Produced water handling systems:
E-2
E-3
E-4E-5
E-6
E-7
E-8
From
separators
To slop oil
tank
5
Sludge
out
8
Carbon
filter
Tre
ate
d
Wa
ter o
utle
t
Drain
Water out
From CPI
P-1 P-2
P-1
P-4
P-5
P-9
P-10
P-11
P-12 P-9
P-13
P-14
P-15
P-16
Water storage tank
P-17
P-18
C.P.I
P.W.skimmer
Temporary oil
Storage tank
pumpspumps
Figure 6:produced water handling Overview
Produced Water from the test/production separator is sent to the produced water skimmer
(designed for 3 phase separation), where the dissolved gases are separated and sent to the flare
and oil is skimmed and separated from the produced water. The separated oil is coalesced,
collected and dumped under level control to the slop oil tank. The treated water flows to the
Corrugated Plate Interceptor (CPI)for further de-oiling purposes. Feeds to the CPI include
effluent water from the produced water skimmer and contaminated rainwater from the open drain
system. Treated water from corrugated plate interceptor is sent to a carbon filter for final clean
up prior to disposal to the ocean. The recovered oil from the CPI unit is sent to the slop oil tank.
Slop oil tank accumulates slop oil from the produced water skimmer, oil from the CPI, and
liquids from the closed drain drum. Hydrocarbon liquids collected in the tank is pumped to the
condensate storage tank for export and water separated in the tank is pumped to the
produced water skimmer for treatment by Slop oil and water pumps.
20
PLANT UTILITIES:
Figure 7:Plant Utilities overview
Water plant:
Sea water sucked by bevel pumps from the ocean at Electro-Chlorination Unit (ECU) is pumped
into the sea water storage tank. The stored sea water is used for mainly two purposes, first in
water type fire extinguisher systems and secondly in portable water treatment plant. The treated
portable water is used for domestic purposes at the plant, camp and village.
Instrument Air Plant:
Compressed instrument air plays major roles in valves opening and closing mechanisms. This is
done purposely to avoid the use of electricity which could act as a source of sparks and hence
resulting into explosion. This compressed is processed by two compressors installed at the
Instrument Air Plant by trapping and compressing atmospheric air to the required pressure.
21
Electricity production:
Despite the fact that electricity is not basically recommended for valves operation in gas
industries, but it still plays imperative role in gas production process. It is used to drive motors,
pumps, engines, Programmable Logic Control, office computers and lighting purpose (at the
plant, camp and village). Electricity is generated by using three Gas Engine Generators which
uses gas to generate electricity. The gas is tapped from the Sales Gas Metering Skid. To ensure
constant presence of electricity even in case of plant shut down, then there is emergency tapping
of gas for generators from the export line.
Safety Systems:
Safety running of the plant is both mandatory and crucial aspect that is highly observed in SSI
Gas Plant. To ensure this, a number of safety systems have been installed in entire plant. These
systems include:
Low and High Pressure flare (LPF & HPF).
Fire extinguishers (FM -200, Foam and Water).
Detectors (smoke, flame and gas).
Blow Down Systems.
Shut down systems (Level 1&2).
PART TWO.
22
PROJECT
PROJECT TITLE: MONO ETHYLENE GLYCOL TRAINS EFFICIENCY
EVALUATION.
23
INTRODUCTION
A common method to remove water from natural gas is glycol dehydration. In this process,
mono ethylene glycol (MEG) is used to remove the presence of water in the gas stream. Water
vapor can cause hydrate formation at low temperatures and high pressures or corrosion when it is
in contact with hydrogen sulfide (H2S) or carbon dioxide (CO2), components regularly present
in the gas stream. Meg regeneration units are typically represented by a reflux condenser, surge
drum(heat exchanger), a flash tank, filters, packing’s and a re-boiler. As shown in Figure
1.below The glycol, usually MEG, enters at the gas/gas heat exchangers of the dew point control
trains and absorbs water as it progresses toward the cold separators at the bottom of the trains.
24
TO MEG
REGENERATION
TO CONDENSATE
STABILISER
GAS INLET TO SALES GAS
MEG INJECTION
MEG INJECTION
MEG INJECTION
MEG INJECTION
J-T VALVE
LV
LV
COLD SEPARATOR
Figure 8:Dew point Control Train overview
In cold separator three phase separation of gas ,hydrocarbon condensate and a mixture of water
and glycol is performed. With the help of level transmitters and level valves the cold separator
can easily be drained to respective condensate and meg lines.
Finally, the glycol flows to the Meg units where it is regenerated by boiling off the water and
returned to the dew point control units and closed loop continues.
25
STATEMENT OF THE PROBLEM:
Natural gas downstream from the separators still contain water vapor to some degree . Water
vapor is the common undesirable impurity usually found in untreated natural gas. The main
reason of removing water vapor is due to the fact that vapor becomes liquid under low
temperature and high pressure conditions which can result in problems in the quality of natural
gas and pipeline problems during natural gas transportation. Carefully low temperature
separation is done to prevent pipeline plugging due to hydrate formation, lowering of gas heat
value and pipeline corrosion due to carbon dioxide and hydrogen sulphide formation.
In the scientific facts, one of the challenges pertains to the dehydration of the natural gas is to
ensure continuous supplying of mono ethylene glycol under precise qualities for effectively
separation of natural gas, water and hydrocarbons due to currently plant overloaded situation.
As it is well known that mono ethylene glycol produced from meg trains is used for water
absorption in natural gas stream, dry the gas to a required specification ready to be transported
through pipelines to Dar es salaam to our customers.
In mono ethylene glycol closed loop system we have come across different operating problems
resulting to day to day decreasing train performance even efficiency. As we know mono
ethylene glycol loss (meg loss)seems to be the mostly common problem in these trains and this is
due to meg carry over in condensate lines, pumps leakages, meg exported in sales gas line and
inefficiently /manually meg and condensate separation done by unskilled workers. Overcoming
these losses we need to have a good separation with a required specific residence time, regular
servicing of rubber in pumps, educating people about methods used for meg laboratory
properties determinations, meg utilization and chemistry behind about meg dehydration even
hydrate inhibition.
26
OBJECTIVE:
The general objective of this study is to evaluate the meg trains efficiency from the designing
and normal plant operations, maximum plant operation to the current overloaded situation.
SPECIFIC OBJECTIVES:
To perform the mono ethylene laboratory analysis that will lead to the realization of the
trains status/efficiency when compared to designed and normal train and plant general
performance. i.e. identification of meg quality loss and other chemical properties
To perform simple mathematics on vessels capacity to see if the meg trains can with
stand the new plant performance situation.
To perform trains analysis that will help to know the results of current Meg utilization
and circulation rate against normal operating conditions.
To evaluate Meg units current efficiency and compare it with the designed efficiency.
To tackle the problem of Meg loss which results to more utilization of mono ethylene
glycol due to the fact that it is carried in condensate line. This will lead to installation of
settling tanks for condensate/meg mixture that will increase residence time corresponding
to plant overloaded situation while waiting for dehydration plant expansion.
SIGNIFICANCE OF THE STUDY.
The achievement of this project will be very important since it will help in the trains performance
and meg utilization. This will be achieved during evaluating Meg properties, vessel capacities
and performance of different components in trains. It will also give the train status by
identifying all meg losses and operation problems and it will lead to engineering mathematical
calculation on efficiency of trains for monitoring of trains current performance. The efficiency
evaluation will lead to solve the problem of Meg loss by taking into account all the causes of the
problems and their solutions.
27
LITERATURE REVIEW:
Process description:
Glycol injection is provided by the injection pumps with the minimum to maximum flow rates of
each pump ranging 0.19 – 0.69 m3/hr according to design. The rich glycol is separated from the
condensate in the Cold Separators, about 35-120 minutes retention time dependant on the EG
circulation rate, this is provided for the glycol to ensure proper separation of the glycol and
condensate. The glycol exits the Cold Separators, under level control and flows to the reflux
coils above the packing in the still columns of the EG Re boilers where self refluxing occurs.
The rich glycol is then passed through integral lean/rich glycol coils in the surge tank section of
the M.E.G Re-boilers. After being preheated by the lean M.E.G. in the accumulator the rich
glycol stream flows to the Glycol Flash Tanks which are operating at a lower pressure of 448
kPa (65 PSIG). In the flash tank, any free gases that exist are flashed off and sent to flare. Any
liquid hydrocarbons that have been carried over into the flash tank can also be removed. Under
level controls valves, glycol exits the bottom of the flash tanks and flows to the glycol filters.
Particulate filters (10 micron), and carbon filters filtering dust particles and hydrocarbons
contained in rich glycol ready to be boiled. Upon exiting the filters, the rich glycol proceeds to
the top of the packed section in the glycol still column. In the glycol still column, water is
stripped out of the rich MEG as it flows downward through the 10’-0” packed section consisting
of 25mm Pall rings counter current to the steam that is generated in the MEG Re boilers. The
steam is discharged to the low-pressure flare header at the top of the still column. Once the
desired concentration (temperature) is achieved in the MEG Re boilers. Lean MEG flows by
gravity to the glycol surge tank (integral with the glycol re concentrator). Here it is cooled by
heat exchange with the rich MEG flowing through the integral lean/rich glycol coils. From the
surge tank the glycol flows to the suction of the glycol pumps where it is pressurized for re-
injection in the Gas/Gas Exchangers.
28
FUEL GAS
F L
FILTERSURGE DRUM
RE BOILER
LV
PUMP
R.CONDENSER
pckg
P-11
P-15
P-17
P-19
P-21
CLOSED DRAIN DRUM
FLUSH VESSEL
P-22
P-34
P-40
P-43
P-44
P-46
P-48
P-50
BURNER
P-51
LEAN GLYCOL
P-57
P-58
P-59
G/G EXCHANGER
P-62
FILTER
P-65
P-66
COLD SEPARATOR
RICH GLYCOL
Figure 9:Meg regeneration Unit
29
Meg trains efficiency:
To facilitate a practical Meg trains efficiency assessment there must be a need for a practicable
scheme to relate the plant gas flow rate, gas dehydration practices, meg chemistry and meg units
performance in daily operations and on how they depend one another to facilitate natural gas
quality determination.
Under this section we will deal with chemistry behind of glycol, systems/units capacity and
trains data analysis on monitoring plant operating conditions. Meg circulation(closed loop) under
designed conditions required to operate with normal/ little system glycol loss to the exported gas
and normal train operations.
When plant flow rate increased beyond to its maximum holding capacity stream turbulence
increases resulting to insufficient phase separation due to decreasing cold separator residence
time. This leads to little glycol loss in gas export line but much and more in condensate line. The
condensate line is manually tapped to manually separate condensate and mono ethylene glycol in
order to overcome glycol loss in condensate line. To avoid this loss meg chemistry and vessel
capacity even plant operating data must be taken into considerations.
Perfectly, the trains performance depends much on cold separator capacity, glycol circulation
rate, quality of lean and rich meg required, heat load of re boiler and glycol flash separator
capability.
Due to meg carried in condensate line it comes a time that meg is lost in highly amount that the
surge tank needs to be topped up to overcome circulation problems which can lead to insufficient
gas dehydration. Some amount of meg remains in the system while other leaks out through
pumps and manually separation practices.
Hence during efficiency evaluation, the followings will be well thought-out:
1. Effective make a follow up on the actual amount of Meg topped up in the system by
analyse the data recorded from normal to overloaded situation.
2. Working out the actual amount of meg loss leaking out from the network mostly caused
by meg carried in condensate line.
30
3. Checking vessels operating capacity when compared to designed conditions.
4. Perform efficiency evaluation on data recorded compared to required (recommended)
specifications.
Procedures followed to accomplish the mentioned tasks:
1. Comparing amount topped up to the system and that recovered.
2. Evaluating efficiency of the system by considering data obtained when compared to
required specifications.(meg concentrations, re boiler temperature)
3. Evaluating vessel capacity by comparing their working ability with the designed
specifications.
Mathematical expressions governing vessels capacity, and meg circulation rate, heat load of
re boiler, required settling volume in flush tank, mount of water to be removed in natural
gas.
1) From Petroleum Production Engineering (a computer-assisted approach) by Boyun guo,
William C. Lyons and Ali Ghalambor.
5.045.0
)(
....
k
g
glkAQg
VAQg
velocitygasAreaseparatorcapacitygastorcoldsepara
Nomenclature:
Qg=cold separator gas capacity
A=Area of Cold separator and
V=Volume of cold separator
3) From Petroleum Production Engineering (a computer-assisted approach) by Boyun guo,
William C. Lyons and Ali Ghalambor.
capacityseparatorcoldcontentwatergasRWGratencirculatioglycol ........
Nomenclature:
31
G.W.R=Glycol Water Ratio.
4) From Petroleum Production Engineering (a computer-assisted approach) by Boyun guo,
William C. Lyons and Ali Ghalambor.
pressurepumpQgkwhelectical
pressurepumpQgBHPPumps
intrtimeresidenceQgkflushinvolumesettlingrequired
perhourboilerreofloadheatboilerreofsizeoverall
ratencirculatioglycolperhourreboilerforloadheat
.10000000833.1.
.100000002.
60
min.)(.tan.....
.......
..2000......
Nomenclature:
Qg=cold separator gas capacity.
5)From handbook of natural gas transmission and processing by Saeid Mokhatab
24
).......(.....
outgascontentwateringasofcontentwaterQgremovedbetowaterofamount
Nomenclature:
Qg=cold separator gas capacity.
6) Design/Normal plant capacity according to design The whole plant was designed to operate
under the following specification
32
Table 2:plant specifications according to design
1)The whole plant according to design maximum current situation
Gas Flow Rate, Sm3/d (MMSCF/D)
Train 1: 989,000 (35.0) 1271571.429(45) 1554142.857(55)
Train 2: 989,000 (35.0) 1271571.429(45) 1554142.857(55)
Total: 1,978,000 (70.0) 2543142.857(90) 3108285.714(55)
Hydrocarbon Flow Rate, m3/d (BPD):
5.6 (35.0)
Free Water Flow Rate, m3/d (BPD):
11.1 (70.0)
Operating Pressure, kPag :
11,000/8900 11,000/8900 11,000/8900
Maximum Inlet Temperature ºC :
37.8 (100.0)
Normal Inlet Temperature ºC :
21.5 (70.7)
Minimum Inlet Temperature ºC : 18.9
(66.0)
Specific Gravity, Gas:
0.58 0.575394
33
Design Pressure, kPag :
12500 110 110
Design Temperature, ºC :
Maximum: 65.6
Minimum: -28.9 (-20.0)
Corrosion Allowance in vessels(mm)
1.6 1.6 1.6
HEX Fouling Factor
0.001/0.002 0.001/0.002 0.001/0.002
gas pressure drop in kpa
HEX Tube-Side: 34 HEX Tube-Side:
34
HEX Tube-Side: 34
HEX Tube-Side: 69 HEX Tube-Side:
69
HEX Tube-Side: 69
Gas Composition:
Sweet Sweet Sweet
Inlet Separator Slug Capacity, m3 :
4.0 (141.2)
2)Meg system:
Meg circulation rate
34
0.19-0.69m3/hr.
Output Meg concentration
80/20 v/v (meg to water ratio).
Glycol Concentration, % by Wt.
80 80 80
Glycol Circulation Rate, m3/hr :
0.19 – 0.69 0.19-0.69 0.19-0.69(need to be improved
to cope with current situation)
Mono ethylene glycol chemistry:
Mono Ethylene glycol (ethan-1,2-diol) is an organic compound used as an antifreeze and
hydrate inhibitor in natural gas industry. In its pure form, it is an odorless, colorless, syrupy,
sweet-tasting liquid which is toxic, and ingestion can result in death.
Meg components:
Mono ethylene glycol is produced from ethylene (ethene), via the intermediate ethylene oxide.
Ethylene oxide reacts with water to produce ethylene glycol according to the chemical equation:
C2H4O + H2O → HO–CH2CH2–OH
This reaction can be catalyzed by either acids or bases, or can occur at neutral pH under elevated
temperatures. The highest yields of ethylene glycol occur at acidic or neutral pH with a large
excess of water.
35
i)antifreeze chemistry
Due to its low freezing point and tendency to form glasses, ethylene glycol resists freezing. A
mixture of 60% ethylene glycol and 40% water does not freeze until temperatures below −45 °C
(−49°F).The antifreeze capabilities of ethylene glycol have made it an important component of
natural gas dehydration process where it enhance efficient low temperature three phase
separation by prohibiting water freezing.
Ethylene glycol disrupts hydrogen bonding when dissolved in water. Pure ethylene glycol
freezes at about −12°C (10.4°F), but when mixed with water molecules, neither can readily form
a solid crystal structure, and therefore the freezing point of the mixture is depressed significantly.
The minimum freezing point is observed when the ethylene glycol percent in water is about 70%,
as shown below. This is the reason pure ethylene glycol is not used as an antifreeze because
water is a necessary component as well.
Table 3:Ethylene glycol concentration vs temperature
Ethylene glycol freezing point vs. concentration in water
Weight Percent EG (%) Freezing Point (deg F) Freezing Point (deg C)
0 32 0
10 25 -4
20 20 -7
30 5 -15
40 -10 -23
50 -30 -34
60 -55 -48
70 -60 -51
36
80 -50 -45
90 -20 -29
100 -10 -12
Graph of Freezing temperature vs Meg concentration
Figure 10:Graph of meg freezing point vs concentration
The boiling point for aqueous ethylene glycol increases with increasing ethylene glycol
percentage. Thus, the use of ethylene glycol not only depresses the freezing point, but also
elevates the boiling point such that the operating range for the heat transfer fluid is broadened on
both ends of the temperature scale.
37
Table 4:Boiling point vs concentration
Ethylene glycol boiling point vs. concentration in water
Weight Percent EG (%) Boiling Point (deg F) Boiling Point (deg C)
0 212 100
10 215 102
20 215 102
30 220 104
40 220 104
50 225 107
60 230 110
70 240 116
80 255 124
90 285 140
100 387 197
Here the graph for boiling point vs weight % meg.
38
Table 5:Meg boiling point Vs concentration
ii)hydrate inhibition chemistry:
Because of its high boiling point and affinity for water, ethylene glycol is a useful desiccant.
Ethylene glycol is widely used to inhibit the formation of natural gas clathrates (hydrates) in long
multiphase pipelines that convey natural gas from remote gas fields to an onshore processing
facility. Ethylene glycol can be recovered from the natural gas and reused as an inhibitor after
purification treatment that removes water and inorganic salts.
Natural gas is dehydrated by ethylene glycol. In this application, Mono ethylene glycol (as mist
form) sprayed to dew point control unit heat exchangers and meets a mixture of water vapor and
hydrocarbon gases. This mixture flows down to the cold separator through a J.T valve for gas
throttling. Dry gas exits from the top of the cold separator while condensate and meg are drained
at their respective lines. The glycol and water are separated, and the mono glycol recycled.
Instead of removing water, ethylene glycol can also be used to depress the temperature at which
hydrates are formed. The purity of glycol used for hydrate suppression (mono-ethylene glycol) is
around 80%.
39
To maintain efficiently performance of the system under specifications, avoiding abnormal meg
loss and proper gas dehydration the system must be examined for its currently operating
conditions against the designed ones.
40
METHODOLOGY:
This will involve data taking in meg and dew point control trains even principles from different
literatures. Quality of mono ethylene glycol and dew point can can be monitored and examined
by operators daily data taking exercise. This is done for every hour in control room and after
eight hours by operators in field area. The obtained data from field and results from laboratory
experiments for a period of months from January to August (data in considerations)shows us
how glycol properties fluctuates according to plant different operation situations.(I took data for
august, the time I was in plant and perform lab experiment).On other hand vessel capacities and
operation conditions evaluation was done considering data obtained from operating manuals and
literatures.
Equipment used
i. Data sheets and pen for data taking.
ii. Sampling bottles for laboratory Meg concentration determination, ph meter, hydrometer
and thermometer.
iii. Manuals and literature books.
Experimental part:
To ensure that glycol meet the specific set up concentration required for water dehydration
(80/20v/v lean glycol and 60/40v/v rich glycol) laboratory Meg test was performed.
Mono ethylene glycol concentration plays a great role in natural gas dehydration specifically in
dew point depression and helps much glycol reclamation practice.
Test Sampling points:
Lean MEG soon after pumps.
Rich MEG soon after carbon filters.
Test Procedures:
41
I Pour sample (rich/lean) into a measuring cylinder then immerse probe to get a required
temperature in degree ( F) and meg ph.
Then I insert Hydrometer in a measuring cylinder to obtain MEG specific gravity.
By using the specific gravity, temperature obtained and the Microsoft Excel Program (prepared
for this purpose) I predict the value of lean/rich concentration.
By enter the temperature measured into temperature side of the program. I was varying the
rich/lean concentration ( by try and error) until i got the same value of specific gravity as the one
i have measured.
Then in a program I took rich/lean concentration that gives the same value of specific gravity as
the measured one.
42
RESULTS, CALCULATION AND DISCUSION:
Experimental results:
Meg train 1:
Lean meg
Temperature =100F
Specific Gravity =1.082
Lean meg Ph =7.9
Concentration =74/26(2.85)
Rich meg:
Temperature = 100F
Specific Gravity = 1.064
Rich Meg Ph = 7.4
Concentration = 57/43(1.326)
Pump speed =41.1%
Flow rate in D.P.C = 57362
Rich Meg level = 39.8(process value)
= 40 (set value)
Meg train 2:
Lean meg
Temperature =100F
Specific Gravity =1.084
43
Lean Meg Ph =8
Concentration =78/22(3.55)
Rich meg:
Temperature = 100F
Specific Gravity = 1.070
Rich Meg Ph = 6.7
Concentration = 63/37(1.703)
Pump speed =41.1%
Flow rate in D.P.C = 57362
Rich Meg level = 55.8(process value)
Data for period of months for train’s performance gas flow rates and mono ethylene glycol
utilization.
Monthly average properties of lean glycol in train 1Month TEMP specific Conc(80/20) Ph situation comp
deg f gravity 4max 6-7.5 to design
JANUARY 96 1.086 3.167 7.2 normal
FEBRUARY 95.61818182 1.087 3.35 7.344444444 normal
MARCH 94.875 1.08675 3.167 8.6 normal
APRIL 96.54545 1.086182 3.38 7.425 normal
MAY 97.2 1.086 3.35 7.55 normal
JUNE 99.77777778 1.082 3.167 7.2625 max to overload
JULY 99.71428571 1.083 3.167 7.686 overload
AUGUST 95.625 1.0845 3.167 7.2575 overload
Table 6:lean glycol properties in train1.
44
Graphical representation:
92
93
94
95
96
97
98
99
100
101
JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST
Temperature(F) vs time(Months) for meg lab sample tests
Figure 11:graph showing temperature in meg lab test carried
Calculations:
Test done in laboratory to get meg properties must be done at 100F sometimes temperature
fluctuation results into incorrect laboratory meg data obtained. Here is the laboratory temperature
efficiency evaluation for the data obtained
%92.96
100
10092.96...
.
100..
effytempsamplelab
valuerecomended
valueobtainedaverageefficiency
Purity of glycol determination can sometimes being affected by testing temperature fluctuation.
Also,
45
Specific gravity of lean glycol recommended to be at 1.085 test in laboratory must be done to
check if the glycol conform to a required set value.Below is the efficiency evaluation of glycol
specific gravity test for average of the data taken during this period.
%100
085.1
100085.1...
efficiencygslab
Graphical representation:
Figure 12:Graph showing lean glycol water ratio vs time
%3.99
5.7
10045.7..
%81
4
10024.3...
efficiencyhp
efficiencyionconcentratglycollean
In above calculations average lean glycol concentration from train 1 decreases by 19% ,while ph
deviates by…..% from required specification. This is due to high meg circulation, low vessel
46
capacities even operating plant beyond its normal designed conditions which result to fluid
turbulence.
Monthly average properties of Rich glycol in train 1Month TEMP specific Conc Ph situation cmp
deg f gravity 80/20max 6-7.5 to design
JANUARY 92.85714 1.081143 2.125 6.54 normal
FEBRUARY 92.90909091 1.08145455 2.226 6.511111111 normal
MARCH 93.625 1.08025 2.125 6.42 normal
APRIL 94.36364 0.989833 2.15 6.225 normal
MAY 95 1.0796 2.125 6.233333333 normal
JUNE 98.66666667 1.074 1.86 6.25 max to overload
JULY 98.14285714 1.071 1.63 6.73 overload
AUGUST 94.875 1.07125 1.564 6.485 overload
Table 7: monthly properties of rich glycol in train 1
Graphical representation:
47
0.94
0.96
0.98
1
1.02
1.04
1.06
1.08
1.1
JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST
Lab.Rich glycol s.g vs time(month)
Series1
Figure 13:laboratory rich glycol vs time
%6.85
5.7
10042.6..
)..%32..%(132
5.1
10098.1...
%6..98
085.1
10007.1...
%05.95
100
10005.95...
.
100...
efficiencyhp
ionspecificatrequiredfrombydeviate
efficiencyionconcentratglycolrich
efficiencygslab
effytempsamplelab
valuerecomended
valueobtainedofaverageefficiency
48
Concentration recommended for rich glycol in circulation loop required to be 60/40v/v(1.5) but
these days the value rises up to(66.4/33.4v/v) 1.98 this means that the rich glycol concentration
purity recommended decreases by 32%.According to glycol chemistry stated above this drop
affects glycol properties resulting to poor performance of glycol units and inadequate natural gas
dehydration.
Monthly average properties of lean glycol in train 2Month TEMP specific Conc(80/20) Ph situation comp
deg f gravity 4max 6-7.5 to design
JANUARY 95.42857 1.086857 3.35 6.84 normal
FEBRUARY 95.89 1.0858 3.35 7.7 normal
MARCH 95.5 1.0835 3.35 8.966666667 normal
APRIL 97.54545455 1.084364 3.3 7.625 normal
MAY 97.4 1.0848 3.35 7.625 normal
JUNE 97.22222222 1.085 3.35 6.9 max to overload
JULY 98.57142857 1.0843 3.35 7.8 overload
AUGUST 97.375 1.0815 2.85 7.31 overload
Figure 14:monthly average properties of lean glycol train 2
Graphical representation:
49
Figure 15:monthly average properties of lean glycol
Calculations:
%100
5.7
1005.7..
%5.82
4
1003.3...
%100
085.1
100085.1...
%87.96
100
10087.96...
.
100...
efficiencyhp
efficiencyionconcentratglycollean
efficiencygslab
effytempsamplelab
valuerecomended
valueobtainedofaverageefficiency
50
Again train 2 calculations shows that average lean glycol concentration decreases by 17.5%
,while ph deviates by…..% from required specification. Also this is due to high meg circulation,
low vessel capacity even operating plant beyond its normal designed conditions which result to
fluid turbulence.
Monthly average properties of Rich glycol in train 2Month TEMP specific Conc Ph situation
deg f gravity (60/40)1.5max 6-7.5 comp to design
JANUARY 93 1.082286 2.226 6.42 normal
FEBRUARY 93.38 1.0814 2.226 6.566666667 normal
MARCH 93.625 1.0805 2.226 6.64 normal
APRIL 94.63636 1.08 2.33 6.2 normal
MAY 94.8 1.0808 2.33 6.025 normal
JUNE 95.66666667 1.0822 2.125 6.085714286 max to overload
JULY 99.28571429 1.071 1.8 6.6 overload
AUGUST 95.375 1.073 1.86 6.4175 overload
Table 8:monthly average properties of rich glycol
Graphical representation:
51
Table 9:monthly average properties of rich glycol 2
Again concentration recommended for rich glycol in circulation loop required to be
60/40v/v(1.5) but here the value rises up to(68/32v/v) 2.14 this means that the rich glycol
concentration purity recommended decreases by 43.7%.According to glycol chemistry stated
%3.85
5.7
1004.6..
%7.143
5.1
10014.2...
%5.99
085.1
10008.1...
.%95
100
10095...
.
100...
efficiencyhp
efficiencyionconcentratglycolRich
efficiencygslab
effytempsamplelab
valuerecomended
valueobtainedofaverageefficiency
52
above this drop affects glycol properties resulting to poor performance of glycol units and
inadequate natural gas dehydration.
Table 10:monthly data on dew point control trains
Average monthly data on dew point control unit 2!!
Month
Meg
level(%)
total Injection
rate(lpm)
Cond
level(%)
S. tank
level(%) meg top ups(lts)
rate
JANUARY
normal
FEBRUAR
Y
normal
MARCH
normal
APRIL
normal
MAY
normal
JUNE 55 3.07 60.01 49.2 2667
max to
overload
JULY 55.05 3.085 56.3 49.8 17978.8 overload
AUGUST 46.42 3.32 53.73 51.1 18906 overload
Table 11:monthly average data on dpc 2
Data in table above shows how glycol consumption (based on trains top ups) being affected by
current overloaded situation. This is due to high meg loss caused by insufficient separation in
cold separators facilities which in turn causes decreasing in required meg amount in circulation
loop. According to vessel capacity and mono ethylene glycol chemistry the problem can be
solved by plant facilities expansion. This will emphasize on dehydration systems to provide the
required residence time for effectively separation according to design.
53
54
Vessels capacity evaluation:
According to data obtained above the plant now is operated at overloaded conditions and this
affect more in Meg trains performance. As u can see above the required concentration of lean
meg (80/20v/v meg/water) is not attained now days due to overloading plant operations. Apart
from Meg concentration fluctuation current plant overloading situation resulting to meg trains
and the whole gas dehydration systems to operate inefficiently. Gas capacity of cold separator,
glycol circulation rate, re boiler heat load and pumps functioning are the parameters/working
conditions which are being affected much by now plant overloaded operations.
Effects of plant overloading to the system:
Gas capacity of cold separator can be obtained from whole day capacity of the dew point control
train divide by 24 hours of operation in cold separator. According to design 35mmfsd and 60
minutes were required values of train flow rate and residence time but for current situation the
daily dpc flow rate increases to 55mmfsd while its residence time keep on decreasing due to
increase of gas flow rate. Daily flow/production when divided to 24 hours we get the cold
separator gas capacity per hour. Since it designed to have a residence time of 60 minutes, that is
according to designed capacity of cold separator. By calculations
As per design:
a)cold separator:
24
35.
mmscfdygascapacittorColdsepara
Cold separator Gas capacity=1.45833mmscfhr (41208.33sm3/hr)
Therefore cold separator gas capacity is 41208.33sm3.
Overloaded situation:
24
55.
mmscfdygascapacittorColdsepara
55
Required Cold separator Gas capacity =2.29167mmscfhr (64755.95238sm3/hr)
Therefore we overcapacity the cold separator by= valuedesignedvaluecurrent ..
362238.23547
3)33.4120895238.64755(
sm
sm
14.57
33.41208
10062238.23547
..
100.....%
valuedesigned
valuetyovercapacityovercapaciseparatorcold
This overcapacity of cold separator by 57% of designed capacity resulting to an increase of
20mmscfd of daily production in one dpc train. For both two trains the increase is
40mmscfd.Therefore the whole plant capacity is increased by 57% beyond normal.
b)Glycol re-concentrator:
glycol circulation rate, heat load of re-boiler and overall size of a re-boiler depends much on cold
separator gas capacity. When increasing cold separator capacity even glycol circulation rate and
other parameter stated above will be affected. Let us see how the cold separator affect unit
operations in glycol re-concentrator trains.
1) capacityseparatorcoldcontentwatergasRWGratencirculatioglycol ........
679.2
..1.333.41208)20/80(
310)69.019.0(5.0
,....
......
6
basishourundersm
sm
apacityseparatorccolddesignedRGWdesigned
ratencirculatioglycoloriginalcontentwatergasoriginal
By assuming that gas water content is constant(since no data were taken )
Due to plant overloading the now needed glycol circulation Qg new will be
56
38.693924.
95238.64755679.2)20/80(.
679.2..
.20/80)..(...
.......)..(
..
smnewQg
newQg
Therefore
contentwatergas
andRWGratiowaterglycolwhere
basishourundercapacitytorcoldseparaNewcontentwatergasRWG
perhournewQg
.
Therefore
By how much the system circulation is overloaded?
%71.57
100440000
253924%
100.
%
overloaded
Qgoriginal
Qgoverloaded
The overloaded percent above means that the current system vessels are being overloaded more
than 50% of their normally design. Therefore we need to expand the dehydration sub-plant to
twice as much by installing new two dew point control units and two meg trains. This will allow
the plant to operate under normal operation conditions.
3
363
253924
)10)69.019.0(5.0(8.693924
..
smQg
smsmQg
originalQgnewQgQg
57
from
24
).......(.....
.10000000833.1.
.100000002.
%68.57%
1007.36666
0833.0253924%
100,
.tan...%
%100.
.tan..%
..7.36666
0833.0.440000
).(.).(
...)(.
)(tan.....
%71.57....%
...........
,sin
%71.57.%
%1004400002000
507848000.%
000,848,507
2539242000
2000......
..2000......
3
3
outgasinwateringasofcontentwaterQgremovedbetowaterofamount
pressurepumpQgkwhelectical
pressurepumpQgBHPPumps
overload
overloaded
Vsdesigned
timeresidenceQgkflushofgoverloadin
VsDesigned
Vsnewkflushgoverloadin
designpersmVs
hrshourpersmVs
trrecomendeddesignedQgVsdesigned
houroneofbasistrtimeresidenceQg
Vskflushinvolumesettlingrequired
bewilloverloadedsizereboiler
also
then
perhourboilerreofloadheatboilerreofsizeoverall
ce
overloadedreboiler
overloadedreboiler
again
BtuH
btuH
Qgbtuhourperboilerreofloadheatincrease
ratencirculatioglycolperhourreboilerforloadheat
Since pumps.BHP, electrical consumption(in kwh), even amount of water to be removed both
depends on circulation rate. This shows us that the incoming now gas stream
58
(105mmfscd)contains water 57.71 above compared to that carried with 70mmfscd(normal
operation) that if we want to overcome problems in our whole system we need to expand the
system above 60% of normal design.
Problems facing the system caused by plant overloading:
Cold separator and whole circulation performance:
Due to low residence time compared to the design one, insufficient natural gas dehydration is
obtained, this accompanied with three phase separation failure in which meg is carried in
condensate line. The gas leaving cold separator seems to contain high amount of water compared
to that allowed as a result of often hydrates formation in shell side of gas heat exchangers.
Excess water content in lean glycol produced due to re-boiler temperature fluctuation, low lean
glycol temperature compared to required, high inlet gas temperature, vessels capacity and under
circulation of glycol (not match to this current plant overloaded situation) affects much cold
separator performance which leads to insufficient whole natural gas dehydration process.
Meg to condensate carryover:
Insufficient gravity separation in cold separator due to low residence time results in meg to be
carried out in condensate line. Here the condensate line is manually tapped to get the mixture
allowing it to settle by gravity for some period of time then manually separation is done and
meg obtained is topped up in the system. The whole separation and topping up of meg is
manually without scientific considerations. This leads to insufficient separation which leads to
condensate been injected in a glycol loop. Condensate in glycol system affects the re-boiler
burner resulting to periodical burner failure and circulation pumps leakages. Even though when
this happens the surge tank is topped up to overflow which will result into meg condensate
density separation leading to condensate to be overflow out. Working under this basis (manually
way) still creates some problems to glycol quality and whole system operation cost.
b)Mono ethylene glycol quality:(concentration/temperature)
The obtained data from field and results from laboratory experiments for a period of months
from January to August shows us how glycol properties fluctuates according to plant different
59
operation situations. Its well seen from data collected above that both rich even lean glycol
properties in now overloaded situation they don’t conform to specific/recommended ones.
Compared to normal operations glycol purity in now abnormal plant situation is out of
specification due to water content, inefficient phase separation and re boiler operating
temperature fluctuation.
c) Re-boiler temperature fluctuation
frequently topping up new/recovered lean glycol in the system affects much on units operating
condition especially temperature. From the data collected system re boiler temperature seems to
drop frequently when system is charged with new glycol. Even though sometimes re boiler can
drop due to other factors affecting operations but this seems to be common. Re-boiler
temperature drop can result to lean glycol be out of specifications which can lead to hydrate
formation in heat exchangers.(Nb:I have witness dpc depressurization in plant due to hydrate
formation caused by re boiler temperature drop)
On other side rising up of re boiler temperature above its required specification results to glycol
degradation. This is well explained in glycol chemistry above as u have see above 124C lean
glycol degrades.(Nb:I have witness re-boiler 125C operating temperature when I was in Control
room)
d) Burner failure and pumps leaks:
Due to inefficiently condensate and meg separation caused by plant overloading, condensate is
sometimes carried in the meg circulation system. This affect much re boiler performance since it
present burner failures and pumps leakages which can result in increased operation cost due to
maintenance.
d)Vessels and equipment capacity:
Plant overloading situation creates a big problem in vessel and equipment capacity since it forces
the trains units to operate below the designed efficiency. By considering 57% plant overloading
and normal designed trains efficiency(assuming perfectly 100%) ,the trains efficiency without
consider pumps seems to drops more than 30%.
60
On another side circulation pumps are still able to cope with the overloaded situation because up
to day they still operates below 50%.As we know that these are positive displacement plunger
type still are able to operate. What we have to do is to ensure the meg injection is varying with
natural gas flow rate.
e) Meg loss:
Overloading plant gas flow rate resulting to high meg utilization due to high quantity of gas to be
dehydrated. Due to cold separator over capacity operation proceed, the retention time required
for three phase separation is not attained. This affect much the separation resulting to meg being
carried in condensate line. Apart from manually separation practice of the mixture from
condensate line to be major cause of meg loss also re boiler temperature, and normal loss in sales
gas caused by high flow rate also contributes to the loss.
f) Overloaded situation operational costs:
Man power:
Apart from two field shift operators and one in control room to increase their concentration in the
units. Also the company employs four casual workers for manually meg/condensate separation
practice. This increases manpower operation costs.
i.e
tsh
payementsworcasualmontly
000,680,1
30414000.ker..
Assuming operator paid 1000000tsh per month and he increases concentration on units by two
hours per day. His overtime payment can be calculated as follows
tsh
hourperpayementovertimeoperator
1400
2430
1000000....
By considering operators one hour additional to concentrate with meg unit per day
Two operators and casual workers costs can be calculated as follows
61
tshmonthpertsmanpowertotal 3684200..cos..
%21.84cos...%
1002000000
20000003684200..cos...%
tpowermanincrease
monthpertspowermanincrease
System maintenance:
In current working situation (based on august data collected)
Pumps maintenance costs increases due to several pumps services but there is no data recorded
for this.
Particulate filter change (average 10times per month)which cost about 660 USD
(990000tsh),while during normal operation it was average once after a month.
%cost .increase(system. impurities increases) compared to normal operation.
%90
10066
66660
Activated filter carbon change not nown.
Total maintenance cost
tsh
tsunitsotherfilterspumps
990000
cos..
Mono ethylene glycol utilization:
By considering meg charged to the system(surge tank top up) and meg recovered.
Meg cost can be calculated as follows
Considering data taken August(overloaded situation)
62
tstiontransportawitouttsh
drumlts
tdrummonthperuptoppedlitresmonthpertuptopmeg
cos...4.1170276667
200
150033.82518906
)1(200
cos.......cos...
When compared to normal cost by which averagely meg consumption was 10 drums per month
tshtmegnormal
tmegnormal
12379950cos..
150033.82510.cos..
increase of meg consumption will be
5.8
2000
200018906
100..
....
incr
usemegnormal
usemegnormalusemegnewincr
Meg utilization in overloaded situation seems to be almost nine times that in normal operations.
Total meg trains monthly operational cost (based on August)
tshtoequaliswhich
tnutilizatiomegtotaltenancematotaltmanpowertotal
1174950867...
cos...cos.int.cos..
The new installation of tanks is the proper solution to glycol loss and high operation costs to run
meg trains. But it seems to be more temporally because the production even demand of natural
gas keeps on increases. Apart from that we need proper separation in cold separators that will
conform to new flow rate even being able to hold more for future high demand of this new clean
and environmentally friend energy/power solution.
63
Current efforts made to solve the current system problems:
With the use utility saving potentials (utility management opportunities) gravity settling tanks
were recommended and tanks were installed. Here is the simple mathematics showing
Normal/designed conditions
Current system conditions
Recommended improvement
Calculated benefit and implementation cost and
Simple payback or return on investment
Current system condition
Overloading plant situation resulted to high cost of meg trains operations which approximately
cost about Tsh 1174950867 /= monthly.(based on August data)
During normal operating conditions cost was 14,478,950tsh.
Recommended improvement done:
As per current situation the project is purposely intended to provide required residence time
(more than 35 minutes) to reduce meg loss and therefore units operation costs.
To save operation cost of about 1160471917tsh per month new tanks were installed to provide
additional residence time.
Payback period:
months
tshperiodp
savedt
tionimplementaoftperiodP
16
1160471917
0001958731500.
.cos
..cos.
Return of investment:
25.6
16
100.
%100)./1(.
investmentR
periodpinvestmentR
64
Calculated benefit:
After 16 months the implemented tanks installation will return their implementation costs, and
they will continue to overcome the increase meg units operation costs caused by current
overloaded situation(about 1160471917tsh) and allow normal meg units operation costs even if
the plant will continue to operate beyond normal.
65
OVERVIEW:
Based on the literature for mono ethylene glycol chemistry, vessels capacity, and the
regeneration process for glycol presented in literature review above, the rest of project part was
used for parameters, units ,system efficiency evaluation ,problems investigation even suggestion
and discussion on system improvements to the Meg trains. Most of the improvements concerned
on regeneration and dehydration process is especially on the process expansion by which
currently is the use of new tanks to get the required additional residence time(about 35 minutes)
for proper meg and condensate separation. This seems to be proper but temporally solution to the
problem due to the fact that the natural gas production and demand keep on increasing day to
day.
66
CONCLUSSION AND RECOMMENDATION:
Recommendation:
Based on the presented discussions the following conclusions are reached:
As long as the natural gas demand and production increases due to new wells drilling
going on, possibilities of joint venture with nearby small companies like Ndovu and
Tanzania awareness on natural gas, dehydration sub plant expansion more than separation
tanks installed is needed.
As we have seen in above vessels capacity calculations gas capacity of cold separators
even the whole glycol circulation (including meg trains).Vessels and the whole
circulation closed loop are being overloaded for 57.1%.Therefore installation of Two
dew point control trains(or one with capacity twice that present ) and two Meg trains for
meg regeneration (or one with capacity twice that present) will be the solution to current
plant problems caused by abnormal plant operation.
(dehydration process design of new system I will do it as my final year project).
67
Conclusion:
By implementing the natural gas plant expansion stated above the company will work under low
operational costs, high quality and quantity of gas production which will fulfill the country every
day increasing natural gas demand. Investing on plant expanding is a good opportunity for the
company because it will increase company business opportunities through joint venture with
small companies in processing and transportation of natural gas.
68
REFERENCES:
1. Boyun Guo and William C. Lyons, Petroleum Production Engineering “A Computer –
Assisted Approach”
2. Havard Devold, Oil and Gas Production Handbook.
3. Virg Wallentine, The U.S. Natural Gas Transmission Pipeline System.
4. Ali Mesbab, The Effect of Major Parameter on Simulation of Gas Pipeline.
5. Saied Mokhatab, William A.poe and James G.Speight, Handbook of Natural Gas
Transmission and Processing.
69
LIST OF ABBREVIATIONS:
In order to simplify the write-up part, some abbreviations ware used at appropriate places in
this document.
ABBREVIATION DESCRIPTION
AIT Auto Ignition Temperature
API American Petroleum Institute
BDV Blowdown valve
BOPD Barrels of Oil Per Day
BWPD Barrels of Water Per Day
CPI Corrugated Plate Interceptor
d/s Downstream
EGE thylene Glycol
ESD Emergency Shutdown
F&G Fire and Gas
FFG Flame Front Generator
H.C Hydrocarbon
HEL Higher Explosive Limit
HOT Hand Operated Travelling
H.P High Pressure
HVAC Heating Ventilation and Air Conditioning
ID Inner Diameter
JT Joule Thomson
K.O.D Knock Out Drum
LEL Lower Explosive Limit
LO Locked Open
MEG Mono Ethylene Glycol
MMSCFD Metric Million Standard Cubic Feet
MOC Material of Construction
NFPA National Fire Prevention Associati
Nos. Numbers
P&ID Piping and Instrumentation Diagram
PFD Process Flow Diagram
PCS Process Control System
ppm Parts per million
PSD Process Shutdown
PSV Pressure Safety Valve
70
PVSV Pressure Vacuum Safety Valve
RVP Reid Vapour Pressure
SDV Shutdown Valve
SSV Surface Safety Valve
SSSV Sub Surface Safety Valve
S/S Seam to Seam
T/T Tangent to Tangent
UPS Uninterrupted Power Supply
u/s Upstream
USD Unit Shut Down
Table 12abbreviations
Top Related