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Gradutionthesis calculating LPG tank

LY TRUONG TUNGADVANCED PROGAMR K6 NĂM(14)

MINISTRY OF EDUCATION AND TRAINING
HANOI UNIVERSITY OF MINING AND GEOLOGY

LY TRUONG TUNG

GRADUATION THESIS
STUDYING THE TECHNOLOGY OF STORAGE,
TRANSPORTATION LPG AT PV GAS VUNG TAU TERMINAL AND
CALCULATING LPG TANK WITH CAPACITY OF 820M3
.

HANOI - 07/2020


INTRODUCTION
Petroleum is a valuable resource that has been known by humans. However,
until the beginning of the 20th century, when technical science is developed. The oil
and gas were newly rated and used correctly in its importance. In recent years, the
oil and gas industry has continuously grown, after many years of exploration and

search many oil and gas fields have been found, among which are typical ones such
as Bach Ho field Su Tu Den fields, Dai Hung field, Rang Dong field, Lan Tay and
Lan Do fields. The exploitation and use of products have brought a great source of
economic benefits.
Currently, the gas processing industry has grown strongly due to human
demand to use clean raw materials and economically exploited from natural gas and
associated gas fields. Therefore, it is necessary to have a complete storage and
distribution system of gas products in general and liquefied petroleum gas (LPG)
and ensure fire and explosion safety. This is also a matter of great concern when
designing and constructing petrochemical refineries
After finding research, collecting documents and obtaining the consent of the
Oil and Gas Faculty of Hanoi University of Mining and Geology chose the topic for
my thesis as "Studying the technology of storage transportation for refrigerated
LPG at PV Gas Vung Tau Terminal and calculating LPG tank with a capacity
of 820m3". The contents of the thesis include the main issues:
-

Overview of the Vietnam Gas Industry.

-

Introduction of LPG, storage, and transportation of LPG.

-

Study the technology of storage transportation for LPG at PV Gas Vung
Tau Terninal.

-

Calculating tank with capacity of 820m3.

1


ACKNOWLEDGMENT
In the process of doing the project, the large workload with limited time, so I
can not avoid mistakes during the process of completing this thesis. I hope all of our
beloved teachers would review and help me perfect my project.
I am pleased to express my profound gratitude to Dr. Cong Ngoc Thang and


all the teachers of Oil and Gas Faculty - major in Oil refining and Petrochemistry
have been dedicated to helping me carry out and gather the necessary figures for
you to complete this thesis.
Thank you sincerely!

Ha Noi

Ly Truong Tung

2


TABLE OF CONTEN
INTRODUCTION .....................................................................................................i
ACKNOWLEDGMENT ..........................................................................................ii
TABLE OF CONTENT ..........................................................................................iii
LIST OF TERMINOLOGY ....................................................................................vi
LIST OF TABLE ....................................................................................................vii
LIST OF DRAWINGS, GRAPHS .........................................................................viii
LISH OF DIAGRAM ...........................................................................................ixY
CHAPTER 1 : OVERVIEW OF VIETNAM OIL AND GAS INDUSTRY...............1
1.1. Introduce of natural gas .....................................................................................1
1.2. The origin of oil and gas.................................................................................... 1
1.3. Composition and classification of natural gas................................................... 1
1.3.1. Composition ................................................................................................1
1.3.2. Classification ...............................................................................................2
1.4. Gas processing ...................................................................................................3
1.4.1. Removing mechanical impurities.................................................................3
1.4.2. Gas sweetening processes. ..........................................................................3
1.4.3. Water separation.......................................................................................... 4
1.5. Application of gas product .................................................................................4
1.5.1. Used as fuel................................................................................................. 4
1.5.2. Used as a raw material ................................................................................5
1.6. Overview of VietNam’s Gas Industry.................................................................5
1.6.1. Potential development of gas market in VietNam .......................................5
1.6.2. Gas exploitation in Vietnam ........................................................................7
CHAPTER 2: INTRODUCTION OF LPG, STORAGE AND TRANSPORTATION
LPG .......................................................................................................................... 8
2.1. Introduction of LPG.......................................................................................... 9
2.1.1. Properties of LPG........................................................................................ 9
2.1.2. LPG Gas Manufacturing. ...........................................................................11

3


2.1.3. LPG Uses.................................................................................................. 12
2.1.4. Benefits of LPG .........................................................................................13
2.2. Vietnam’s market gas........................................................................................13
2.3. Transportation and Storage LPG...................................................................... 14
2.3.1. Transporting LPG...................................................................................... 14
2.3.2. Storage of LPG ..........................................................................................14
2.4. Type of tanks ...................................................................................................15
2.4.1. Definition.................................................................................................. 15
2.4.2. Situation of building LPG storage tanks in Viet Nam................................ 18
CHAPTER 3: THE TECHNOLOGY OF STORAGE, TRANSPORTATION FOR
LPG AT PV GAS VUNG TAU TERMINAL .........................................................20
3.1. Overview of PV Gas Vung Tau refrigerated LPG storage ...............................20
3.1.1. Systems and operating equipments for refrigerated LPG in refrigerated
LPG storage ........................................................................................................20
3.1.2. Systems and operating equitments for pressurized LPG in refrigerated LPG
storage ................................................................................................................. 23
3.1.3. Equipments List of of PV Gas Vung Tau refrigerated LPG storage......... 25
3.2. Overview of PV Gas Vung Tau pressurized LPG storage .............................33
3.2.1 OVERVIEW OF MAIN EQUIPMENTS. ......................................................33
3.2.3. DESCRIPTION THE TECHNOLOGY OF IMPORT, STORAGE AND
EXPORTING PRODUCT OF LPG STORAGE TANK ........................................33
CHAPTER 4 : CALCULATING LPG TANK WITH CAPACITY OF 820 M3 ......36
4.1. Theoretical calculations ...................................................................................36
4.1.1. Temperature ...............................................................................................36
4.1.2. Working pressure, calculated pressure. ......................................................36
4.1.3. Joint Efficiency .........................................................................................36
4.1.4. Additional coefficient calculated thickness............................................... 37
4.2. Tank selection and calculation parameters....................................................... 37
4.2.1. Purpose of design LPG tank .....................................................................37

4


4.2.2. Design options of LPG tank ......................................................................38
4.2.3. Parameter of LPG storage .........................................................................39
4.2.4. Material for construction ...........................................................................39
4.2.5. Select the welding method for the tank .....................................................40
4.3. Calculate the thickness of the body tank ..........................................................40
4.3.1. The state of the calculation ........................................................................40
4.3.2. Calculate the pressure when the tank contains LPG ..................................40
4.3.3. Calculate the thickness of shell tank under internal pressure .....................41
4.4. Calculate the thickness the head tank.............................................................. 42
4.5. Calculate the total weight of tank ....................................................................43
4.6. Fire explosion risk and mitigation for LPG tanks............................................ 43
CONCLUSIONS AND RECOMMENDATIONS ..................................................45
REFERENCE......................................................................................................... 46

5


LIST OF TERMINOLOGY
ASME

American Society of Mechanical Engineer

APP

Appendix

BOG

Boil-Off Gas

BSR

Binh Son Refinery

CS

Carbon Steel

FIC

Flow Indicating Controller

GPP

Gas Processing Plan

LDA

Loading Arm

LCP

Local Control Panel

LPG

Liquefied Petroleum Gas

LSL

Low Level Swtich

MCR

Main Control Room

PCV

Pressure Control Valve

PSV

Pressure Safety Valve

PSLL

Pressure switch low low

SDV

Shutdown Valve

UCP

Unit Control Panel

6


LIST OF TABLE
No

Name of Table

Content of table

Page

1

Table 2.1

Specifications of LPG

9

2

Table 3.1

Parameters of piping

20

3

Table 3.2

Parameters of refrigerated propane tank

22

4

Table 3.3

Parameters of refrigerated butane tank

22

5

Table 3.4

Parameter of pressurized LPG tank

24

6

Table 3.5

High pressure controls the flare

24

7

Table 3.6

Requirements of equitment

25

8

Table 3.7

Equipment List

25

9

Table 4.1

Parameter of LPG storage

39

7


LIST OF FIGURE
No

Name of figure

Content of figure

Page

1

Figure 1.1

Natural gas production in Vietnam 2009-2019

7

2

Figure 2.1

Fixed Roof Tanks

16

3

Figure 2.2

External floating roof and Internal floating roof

16

4

Figure 2.3

Horizontal Tank

17

5

Figure 2.4

Spherical Pressure Tank

18

6

Figure 2.5

Cylindrical Storage Tank

18

7

Figure 2.6

Storage Tanks in Dung Quat Refinery

19

8

Figure 3.1

Single Containment Tank

21

9

Figure 4.1

Structure of horizontal cylinder storage tank

38

10

Figure 4.2

Principal Dimensions of typical heads

42

.

LISH OF DIAGRAM
No

Name of

Content of diagram

8

Page


.

diagram

1

Diagram 3.1

Overview of refrigerated Propane transport, storage

26

technology of refrigerated LPG storage tank
2

Diagram 3.2

Overview of refrigerated Propane transport, storage

29

technology of refrigerated LPG storage tank
3

Diagram 3.1

The process of mixing Bupro products

9

32


CHAPTER 1
OVERVIEW OF VIETNAM OIL AND GAS INDUSTRY
1.1. Introduce of natural gas
Natural gas is a naturally occurring hydrocarbon gas mixture consisting
primarily of methane, but it commonly includes varying amounts of other higher
alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen
sulfide, or helium. It is formed when layers of decomposing plant and animal matter
are exposed to intense heat and pressure under the surface of the Earth over millions
of years [1].
Natural gas is a valuable fuel source, almost non-renewable. It represents a
significant economic activity, production, and human life in the present civilized
age.
1.2. The origin of oil and gas
Currently, the exact origin of oil and natural gas is unknown but can only be
explained by various theories. Of those theories, organic origin theory is the most
accepted by many scientists.
According to this theory, reasonably the remains of plants and animals which
are mainly algae in the sea. It has been depositing and accumulating with layers of
inorganic sedimentary rocks to the bottom of the sea millions of years ago. The long
process may take place in three stages: biotransformation by a bacterium, chemical
transformation under the effect of appropriate geochemical conditions, and the
movement of products in Earth's crust [2].
The process of forming oil and gas is very slow, lasting for tens or hundreds
of millions of, so the age of oil and natural gas is very large.
1.3. Composition and classification of natural gas
1.3.1. Composition
The composition of natural gas and associated gas is divided into
hydrocarbon compounds and non-hydrocarbon compounds.

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1.3.1.1. Hydrocarbon content
Natural gas is a hydrocarbon mixture consisting primarily of saturated light
kinds of paraffin such as methane and ethane, both of which are gaseous under
atmospheric conditions. The combination also may contain other hydrocarbons,
such as propane, butane, pentane, and hexane.
Even the heavier hydrocarbons occur in natural gas reservoirs for the most
part in gaseous form because of the higher pressures. They usually liquefy at the
surface (at atmospheric pressure) and are produced separately as natural gas liquids
(NGLs), either in field separators or in gas processing plants. Once separated from
the gas stream, the NGLs can be further separated into fractions, ranging from the
heaviest condensates (hexanes, pentanes, and butanes) through liquefied petroleum
gas (LPG; essentially butane and propane) to ethane. This source of light
hydrocarbons is especially prominent in the United States, where natural gas
processing provides a major portion of the ethane feedstock for olefin manufacture
and the LPG for heating and commercial purposes.
1.3.1.2. Non-hydrocarbon content
Other gases that commonly occur in association with the hydrocarbon gases
are nitrogen, carbon dioxide, hydrogen, and such noble gases like helium and argon.
Nitrogen and carbon dioxide are noncombustible and may be found in substantial
proportions. Nitrogen is inert, but, if present in significant amounts, it reduces the
heating value of the mixture; it must, therefore, be removed before the gas is
suitable for the commercial market. Carbon dioxide is removed in order to raise the
heating value, reduce volume, and sustain even combustion properties.
Often natural gases contain substantial quantities of hydrogen sulfide or
other organic sulfur compounds. Sulfur compounds are removed in processing, as
they are toxic when breathed, are corrosive to plant and pipeline facilities, and are
serious pollutants if burned in products made from sour gas. However, after sulfur
removal, a minute quantity of a noxious mercaptan odorant is always added to

2


commercial natural gas in order to ensure the rapid detection of any leakage that
may occur in transport or use.
1.3.2. Classification
Natural gas is extracted from gas fields, associated gas is extracted from oil
fields and aslo the oil exploitation process. The main components of natural gas and
associated gas are methane and propane; butane. Besides, it contains many acidic
compounds such as : H2S, CO2. Based on this property can be classified into sour
gas or sweet gas.
In addition, we can be classified by hydrocarbon content (C 3+). Gas rich in
propane, butane (over 150g/m3) is called fat gas, which is used to make LNG, LPG,
etc. The gas containing less hydrocarbon (less than 50g/m 3) is called dry gas - which
is used as a fuel for industrial and life, materials for organic synthesis technology,
raw materials for the production of fertilizer, ethylene, acetylene, ethanol...[3].
1.4. Gas processing
1.4.1. Removing mechanical impurities.
The appearance of mechanical compounds in the gas adversely affects the
equipment's operation, unsafe in use, and affects the quality of the product.
Consequently, the incoming material must separate the mechanical compounds from
the gas. Removing natural gas from mechanical impurities is carried out mainly by
mechanical devices and is usually classified into two methods: dry cleaning method
and wet cleaning method [3].
1.4.2. Gas sweetening processes.
In the composition of natural gas and associated gas, in addition to
hydrocarbons, there are acid gases such as CO2, H2S, and organic sulfur compounds
COS, CS, mercaptan (RSH), thiophene and other compounds. The presence of CO 2,
H2S, RSH facilitates metal corrosion, environmental pollution, catalytic poisoning;
they have an unpleasant odor that affects human health.[]
Sweetening processes is reducing the content of sour gas (acid gas) to the
lowest acceptable level. When selecting gas cleaning methods, attention should be

3


paid to the component evaluation of materials, including impurities, which are
required in the finished gas. To remove acid gas from natural gas and associated
gas, methods can be used:[3]
-

Absorption method.

-

Adsorption method.

-

Menbrane method.

1.4.3. Water separation.
When exploited from the platform, associated gas and natural gas are often
mixed with a quantity of water. This amount of water is in the process of
transporting and processing gas at low temperatures; it can form hydrate. The
method of forming hydrate has a significant impact: Hydrate can stick to equipment
that damages the device, making the diameter smaller and more likely to be sealed
while the gas pipe is working at high pressure so very danger of broken pipe and
valve phenomenon. On the other hand, in the presence of water and H 2S, favorable
conditions will accelerate the corrosion process.
Hydration formation occurs when the partial pressure of water vapor in the
gas mixture is higher than the hydrate's saturated vapor pressure. Thus, to reduce the
ability to form a hydrate, it must be added to inhibitors or lowering the water
content in the gas, then the partial pressure of water vapor in the gas will be lower
than the pressure of the hydrate so that it will stop hydration formation. The
dehydration process consists of the following methods [3]
-

Gas drying process by adsorption method.

-

Gas drying process by absorption method.

-

Using hydrate inhibitor

1.5. Application of gas product
1.5.1. Used as fuel
In many countries, gas has been used to generate electricity. In other
industries, we can be used for burners in factory for producing construction

4


materials, steel refining, steel ceramics, high-class glass, and other technical
requirements of food processing, fiber factories ...
In transporting, LPG can be used to replace fuels such as petrol or diesel for
cars. It is a clean fuel, less polluting the environment.
Besides, the gas is also used for domestic cooking, and services (hotels,
restaurants) are also used for heating or air conditioning systems in large centers.
1.5.2. Used as a raw material
They are producing urea fertilizer for agriculture.
Manufacture of methanol, then it can be prepared to MTBE, synthetic fibers;
Methanol is also the primary raw material to produce many valuable industrial
products such as : formalin, acetone, methyl methacrylate (MMA), dimethyl
terephthalate (DMT), olefin, etc.
Especially, it can be widely used in the petrochemical industry. It can be used
to make of PVC, PE, PA, PES synthetic fibers, synthetic paints, synthetic detergents
etc.
1.6. Overview of VietNam’s Gas Industry
1.6.1. Potential development of gas market in VietNam
Vietnam oil and gas industry has a great potential as it plays a vital role in
Vietnam’s industrial development.Vietnam has proven gas reserves of 6.8 trillion
cubic feet. Besides crude oil, Vietnam also produces associated and natural gas from
several fields. Vietnam’s natural gas production and consumption have been rising
rapidly since the late 1990s, with further increases expected as additional fields
come on stream.
Vietnam's natural gas industry has developed a long way from its first small
onshore field located in Thai Binh province and south of Hai Phong province.
Today there are three major reserve basins located in southern Vietnam are Cuu
Long, Nam Con Son, and Malay -ThoChu - which supply the power generation and
fertilizer projects currently under operation [4].

5


The modern natural gas industry was born in 1995, with the production of
associated gas from the Bach Ho oil field to the Ba Ria Power Plant, which had an
output of under 3 million cubic meters per day. Three years later, with the Dinh Co
Gas Processing Plant and PV Gas Vung Tau Terminal facilities' introduction, gas
output from this pipeline system was raised to over 1 billion cubic meters per
year[4]. According to the development plan of Vietnam's gas industry to 2025, with
the orientation to 2035, the target of developing Vietnam's gas market is associated
with the National Power development Strategy and Planning.
-

Song Hong Basin: potential recovery of about 550 - 700 million tons of
oil in which is mainly gas, accounting for 14% of Vietnam's total
potential.

-

Phu Khanh Basin: potential of 300 - 700 million tons of oil equivalent,
accounting for 10% of Vietnam's potential reserves.

-

Cuu Long Basin: is a rift basin off southern Vietnam, and the most
important petroleum producing basin in the country. The Cuu Long
Basin is assessed to have the largest potential reserve of 700 - 800
million m3 of oil equivalent, accounting for 20%. This includes 270
million tons of oil and 56 billion m3 of associated gas. Currently
exploiting Bach Ho mine (1986), Rong mine (1994), Rang Dong (1998).

-

Nam Con Son Basin: holds 650 - 750 million tons of oil equivalent,
accounting for 17% of the total potential, of which gas accounts for 35 38% of the reserve. According to the assessment of the tank's reserves
include 74 million tons of oil, 15 billion m 3 of associated gas, 159 billion
m3 of unregulated gas, and 23 million tons of condensate. The
preeminent feature is that the amount of CO2 accounts for negligible.
Currently exploiting Lan Tay and Lan Do.

-

Tu Chinh - Vung May Basin: potential of about 1 - 1.5 billion m3 of oilbearing gas.

6


-

Malay - Tho Chu Basin: potential is about 5% (150 - 230 million tons of
oil), which are 12 million tons of oil, 3 billion m3 of associated gas, 13
billion m3 of non-associated gas and 2 million tons of condensate.

Figure 1.1 Natural gas production in Vietnam ( 2009-2019) [5]
1.6.2. Gas exploitation in Vietnam
Vietnam has vast seas and continental shelves and also a place with great oil
and gas prospects. Oil and gas exploration and exploration activities in Vietnam
have been deployed in the hammock of Hanoi and the An Chau lowlands since the
1960s with the help of the Soviet Union. On the southern continental shelf, this
work has been carried out by foreign companies such as Mobil, Pecten, etc.[6]

7


Nowadays, based on geological-geophysical research results, seven
prospective sedimentary basins have been stored in oil and gas basin on the
continental shelf of the country. These are the Song Hong Basin, the Phu Khanh
Basin, the Cuu Long Basin, the Nam Con Son basin, the Malaya - Tho Chu basin,
the Tu Chinh - Vung May basin, and the Truong Sa - Hoang Sa basin. In our
country, oil and gas fields were discovered and exploited from the seabed in the
southern continental shelf, where the depth of 50-200m of water and in the
geological structure depth from 1,000m to over 5,000m. . Some mines in the Cuu
Long basin (considered to be of the best quality basin) such as Bach Ho and Dai
Hung in Nam Con Son basin are oil-containing both in basement rocks.
In 2021, gas exploitation to begin at White Lion field. With the development
of White Lion field, the total oil and gas production is expected to be 52.4 million
barrels of oil and condensate and 420 billion cubic feet of gas, contributing
significantly to long-term gas exploitation plans of the Vietnam Oil and Gas Group.
White Lion will be the main gas source for the Dinh Co 2 gas processing plant,
which will become operational in the fourth quarter of 2020[7].

8


CHAPTER 2
INTRODUCTION OF LPG , STORAGE AND
TRANSPORTATION LPG
2.1. Introduction of LPG
Liquefied petroleum gas (LPG) is a hydrocarbon gas fuel extracted from
crude oil or natural gas. LPG exists as gases in the ambient temperature, but with
applied moderate pressure, it is liquefied. LPG is a mixture of petroleum gases,
mainly butane and propane. In Vietnam, the commercial LPG might contain
hydrocarbons mixture of propane, propylene, butane (normal-butane or isobutane) and butylenes (including isomers) [8].
2.1.1. Properties of LPG
At normal temperatures and pressures, LPG will evaporate. Because of this,
LPG is supplied in pressurized steel bottles. In order to allow for thermal expansion
of the contained liquid, these bottles are not filled completely; typically, they are
filled to between 80% and 85% of their capacity.
Table 2.1 Specifications of LPG [8]
Properties

Units

Propane

Butane

Boiling Point

0

C

-42 to -45

-0.5 to -0.2

Flame Temperature

0

C

520

500

Density

Kg/m3

1.83

2.46

Molecular Weight

Kg/kmole

44.097

58.12

Heat Capacity

kJ/kg0C

2,512

2,386

9


Vapor Pressure
150C
200C

Bar

250C
Total Heat

Kcal/kg

6,5

0,8

9

2,75

19,6

7

12000

11800

2.1.1.1. Density
LPG at atmospheric pressure and temperature is a gas that is 1.5 to 2.0 times
heavier than air. It is readily liquefied under moderate pressures. The liquid's
density is approximately half that of water and ranges from 0.525 to 0.580 at 15 0C.
Since LPG vapor is heavier than air, it would generally settle down at ground level/
low lying places, and accumulate in depressions.
2.1.1.2. Vapour pressure
The pressure inside a LPG storage tank/ cylinder will be equal to the vapour
pressure corresponding to the temperature of LPG in the storage tank. The vapour
pressure is dependent on temperature as well as on the ratio of mixture of
hydrocarbons. At liquid full condition any further expansion of the liquid, the
cylinder pressure will rise by approxiate 14 to 15 kg./sq.cm. for each degree
centigrade. This clearly explains the hazardous situation that could arise due to the
overfilling of cylinders.
2.1.1.3. Flammability
LPG has an explosive range of 1.8% to 9.5% volume of gas in the air. This is
considerably narrower than other standard gaseous fuels. This indicates the hazard
of LPG vapor accumulated in a low lying area in the leakage or spillage eventuality.
The auto-ignition temperature of LPG is around 410-580 deg. C and hence it will
not ignite on its own at normal temperature. Entrapped air in the vapor is hazardous
in an unpurged tank/ cylinder during pumping/ filling-in operation. Given this, it is
not advisable to use air pressure to unload LPG cargoes or tankers.
2.1.1.4. Commistion

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The combustion reaction of LPG increases the volume of products in
addition to the generation of heat. LPG requires up to 50 times its own volume of
air for complete combustion. Thus it is essential that adequate ventilation is
provided when LPG is burnt in enclosed spaces; otherwise, asphyxiation due to
depletion of oxygen apart from the formation of carbon-dioxide can occur.
2.1.1.5. Odor
LPG has only a very faint smell, and consequently, it is necessary to add
some odourant, so that any escaping gas can easily be detected. Ethyl Mercaptan is
normally used as a stenching agent for this purpose.
2.1.1.6. Colour
LPG is colorless both in the liquid and vapor phases. The distinctive smell
that people associate with LPG is actually added to it as a safety measure.
Without the addition of an odourant, leaking gas could collect without being
detected. The specification is based on a person with a normal sense of smell being
able to identify the odourant's distinct smell at a specific percentage of LPG in air,
simulating a leak.
2.1.1.7. Toxicity
Even though slightly toxic, LPG is not poisonous in the vapor phase, but can,
however, suffocate when in significant concentrations because it displaces oxygen.
Because of this, the vapor posses mild anesthetic properties.
2.1.2. LPG Gas Manufacturing.
2.1.2.1. Raw materials for LPG production.
LPG comes from two sources, with roughly 60% stripped from raw natural
gas during natural gas processing and approximately 40% of the LPG coming from
crude oil refinery process.
2.1.2.2. LPG Process Description
After the crude oil is stabilized - in the process of transporting to the refinery,
important quantities of LPG and lighter components (methane, ethane) are still in
the oil taken to the refinery. Here the crude oil is taken to the fractional distillation

11


tower. Gases of light composition include LPG, ethane, and methane. Other
components include heavy parts.
Depending on each case, we need to apply a method production of LPG in
gas processing plants such as compression method, cooling method, absorption
method, adsorption method.
An LPG production process consists of 3 main stages:
-

Prepare materials.

-

Processing gas

-

Mixing LPG ingredients

The choice of gas processing method is determined by the physical and
chemical properties of the gas mixture and the development of gas processing
technology.
The mixing stage is the simplest of all LPG production stages. Depending on
the market demand for LPG products, manufacturers after having gas components,
including C3 and C4, will mix them in an appropriate proportion. In the process of
mixing LPG components, the technology depends on the primary ratio of butane,
propane and equipment productivity.
2.1.3. LPG Uses
When LPG is used to fuel internal combustion engines, it is often referred to
as autogas. In some countries, it has been used since the 1940s as an alternative fuel
for spark - ignition engines. LPG is a versatile fuel and used around the world as an
alternate fuel for various LPG applications including residential, commercial,
industrial, agriculture and autogas. In areas lacking natural gas, LPG is the best
alternative fuel. Heating, cooking, hot water and drying are common LPG
applications.
Uses of LPG in the home: LPG used in your home is typically suppliedin
LPG gas bottles. Main uses of LPG in your home, including cooking, heating, hot
water, autogas, aerosol propellant, air conditioning refrigerant and back-up
generator applications.

12


Uses of LPG in agriculture: Crop drying is one of the most common use for
LPG in agriculture. Grains, nuts, tobacco and dried fruit are just some examples of
agricultural products dried using LPG. Moisture must be removed from agricultural
products to prevent spoilage.
Uses of LPG in the industry: Using of LPG in the industry: Used to metal
furnaces, welding, cutting steel, cooking and processing glass, canning sterilization,
etc.
Uses of LPG in transportation: It is the fuel to replace petrol because of
high octane value. LPG provides a nearly 50% reduction in greenhouse gas
emissions and an 80% reduction in CO2 as compared to conventional gasoline.
2.1.4. Benefits of LPG
LPG is a clean burning smoke-free fuel that supports cleaner air quality.
Unlike many other fuels, it contains low levels of NOx, particulate matter (PM)
which means it is suitable for both indoor and outdoor use.
-

LPG emits 33% less CO2 than coal and 12% less than oil

-

Heating oil is 17% more carbon intensive than LPG

-

Coal is 50% more carbon intensive than LPG

-

LPG combustion emits almost no PM

-

Cleaner-burning and no sulfur

2.2. Vietnam’s market gas
LPG was introduced to Vietnam since early 1990s. The initial Vietnam LPG
market size is just about 50,000 tons, mainly imported and using in the household
area.
The PV GAS' launch of the Gas Processing Plan Dinh Co t, which produce
about 300,000 tons per year at that time, accelerated the consumption. LPG now
becomes popular and be used vary from cooking to industrial production. Since
2009, Vietnam LPG market has added a new LPG supply from the Dung Quat oil
refinery.

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Since July 2009, Dung Quat oil refinery has officially provided LPG to the
market with an output of about 130,000 tons (2009). In 2019, with the LPG
production volume of Dung Quat oil refinery about 500,000 tons/year, GPP Dinh
Co, and GPP Ca Mau, about 400,000 tons/year will meet over 50% of total LPG
demand of the country [9].
With a target of 500,000 tons/year, LPG of Dung Quat Oil Refinery accounts
for about 30% of the domestic demand in recent years. Currently, Binh Son
Refinery and Petrochemical Company (BSR) - the management and operation unit
of Dung Quat Oil Refinery currently has 12 customers consuming LPG, of which
PV Gas North, PV Gas South, and PV Gas Trading have a structure. Biggest
consumption, accounting for 16-18% / per unit. [9]
Apart from local production, at present, half of the market demand must be
fulfilled with imported LPG. According to statistics from the General Department
of Customs, in May 2019, the country imported 124.1 thousand tons of liquefied
gas, worth about 71.7 million USD.
The South is still considered the largest market and has the highest demand,
accounting for about 66% of LPG demand of the whole country, the North and the
Central with about 30% and 4%.
2.3. Transportation and Storage LPG
LPG is widely used in many industries and is indispensable in some
countries, especially those with developed industries. Therefore, LPG storage,
transport and storage are of particular interest.
2.3.1. Transporting LPG
To facilitate LPG storage and transport for use, people often liquefy the gas
because butane and propane are easy to liquefy at low pressure.
Depending on the manufacturing plant's location, the consuming markets,
generally LPG is transported by pipelines. Transporting LPG from one region to
another, or from a production site to a destination, can be carried by sea, rail, or
road. On the vehicles, we must use a tank under high pressure and have a transfer
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pump system. For household consumers in the household, they can use suitable
piping systems or containers made of steel.
2.3.2. Storage of LPG
People can store LPG on the ground or in the ground depending on the level
of storage, consumption and conditions in different regions.
- Storage on the ground
LPG storage equipment is pressure equipment and made in the shape of a
horizontal cylinder; the two heads are hemispherical or ellipsoidal, maybe it can
store LPG in spherical tanks because it can withstand high pressure. There are
safety devices installed in all tanks in the storage process.
Depending on the market's needs or the purpose of requiring LPG, people
use small to large tanks depending on the different volume levels.
- Storage in the ground
We can store LPG in the ground. This storage method is safe and
effective, but only implemented in several countries with developed industries
such as the US, UK, and Canada.
2.4. Type of tanks
2.4.1. Definition
A tank is a type of construction work serving the preservation of various fuel
types, mainly liquid or gaseous fuel. Currently, people have created tanks with large
capacity and high-pressure resistance.
2.4.1.1. Low-pressure storage tanks
a. Fixed Roof Tanks
A fixed roof tank is a type of storage tank, used to store liquids. There will
always be a vapor space between the liquid surface and the roof. The roof may be
flat, cone - shaped, domed. A pressure-vacuum valve, commonly installed on many
fixed roof tanks, allows the tank to operate at a slight internal pressure or vacuum.
This valve prevents the release of vapors during very small changes in temperature,
barometric pressure, or liquid level [10].

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