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Unit 1

PetrochemistryReading 1

The petrochemical industry is not commonly associated with terms like renewable

energy and sustainability. Nevertheless it is fair to assume that the products of this

industry will stay a commodity of our society for quite a long time. So even though the

vision is that the use of non-renewable resources in time will be restricted, there is much

reason to address issues like process optimisation, energy savings and reduced

environmental impact of the petrochemical industry.

The petrochemical industry is mainly based on three types of intermediates, which

are derived from the primary raw materials. These are the C 2-C4 olefins, the C 6-C8

aromatic hydrocarbons, and synthesis gas (an H 2 /CO 2 mixture).

In general, crude oils and natural gases are composed of a mixture of relatively

unreactive hydrocarbons with variable amounts of nonhydrocarbon compounds. Thismixture is essentially free from olefins. However, the C 2 and heavier hydrocarbons from

these two sources (natural gas and crude oil) can be converted to light olefins suitable as

starting materials for petrochemicals production.

The C 6-C8 aromatic hydrocarbonsthough present in crude oilare generally so

low in concentration that it is not technically or economically feasible to separate them.

However, an aromatic-rich mixture can be obtained from catalytic reforming and cracking

processes, which can be further extracted to obtain the required aromatics forpetrochemical use. Liquefied petroleum gases (C 3-C4) from natural gas and refinery gas

streams can also be catalytically converted into a liquid hydrocarbon mixture rich in C 6-C8

aromatics.

Synthesis gas, the third important intermediate for petrochemicals, is generated by

steam reforming of either natural gas or crude oil fractions. Synthesis gas is the precursor

of two big-volume chemicals, ammonia and methanol.

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Definitions

API gravity: An arbitrary scale expressing the density of petroleum products.

Flash point: Lowest temperature at which a petroleum product will give off sufficient

vapor so that the vapor-air mixture above the surface of the liquid will propagate a

flamme away from the source of ignition.

Boiling range: The range of temperature (usually at atmospheric pressure) at which

the boiling (or distillation) of a hydrocarbon liquid commences, proceeds, and finishes.

OPEC: Organization of Petroleum Exporting Countries

ASEAN: Association of South East Asian Nations

Barrel = 159 liters

Gallon = 3,78 liters (USA) = 4,54 liters (UK)

GAMMAR FORCUS

1. Reported speech

said that

form: S + said to + Obj + that + S + V + O

told (changed)

2. Relative clauses (adjective clause)

Reading 2: REFINERY OPERATIONS

The function of the refinery is to convert crude oil into the finished products

required by the market in the most efficient and hence most profitable manner.

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The methods employed necessarily vary widely from one refinery to another,

depending on the crude processed, the nature and location of the market, the type of

equipment available, and many other factors. However, for simplification, it may beconsidered that all refining processes fall into one of four basic categories.

The first category is fractionation or distillation . This method of physically

separating a mixture of compounds was the earliest process used in petroleum refining,

and today is still one of the most important. However, since it is not generally possible to

separate the complex petroleum mixtures into individual compounds, such mixtures are

segregated into fractions or "cuts", each of which is characterized by a carefully controlled

boiling range. These cuts are then further processed or utilized in the refinery operations.

The second basic type of process , essentially chemical in nature, consists of

converting or chemically transforming certain of these "cuts" into products of higher

commercial value. There are many ways of doing this, but all consist fundamentally of

altering the molecular structure of the components. In the case of a heavy oil, the

molecules may be cracked to form lighter, more valuable products, as for instance in

catalytic cracking and coking. On the other hand, gaseous products may be polymerized

or otherwise combined to form liquid products which may be blended into gasoline. Withcertain processes, e.g. catalytic reforming, both cracking and polymerization take place

concurrently with the more desirable de-hydrogenation, hydrogenation, and isomerization

reactions. The net result of all these transformations is the production of mixtures

containing new arrays of hydrocarbons of higher value than the starting materials.

Nearly all the fractions produced by the processes mentioned above contain

certain objectionable constituents or impurities. The third basic category is , therefore,

treating. This group of processes includes the removal of the unwanted components, ortheir conversion to innocuous or less undesirable compounds. Removal of the impurities

is sometimes accomplished by physical treating, as exemplified by the process for

manufacturing kerosene, wherein sulfur and certain undesirable hydrocarbons are

removed by extraction with liquid sulfur dioxide. Alternatively, the removal may be carried

out by converting the unwanted compounds to a form more readily removed as is done in

the hydrodesulfurization of diesel fuel. Here the sulfur compounds are cracked and

hydrogenated. The sulfur is converted to hydrogen sulfide which can be readily separated

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from the heavier diesel oil by fractionation. An example of the conversion of undesirable

components to innocuous compounds which remain in the product is found in the

gasoline sweetening processes. There the mercaptans present give the product a foul,objectionable odor. The sweetening process merely transforms the mercaptans to organic

disulfides which are less objectionable.

Although sulfur is perhaps the commonest and most troublesome of the impurities

found in petroleum, it is certainly not the only one. Substances such as nickel, vanadium,

and nitrogen may also be present in the crude oil. These impurities are undesirable

because of the difficulty they cause during processing in the refinery or because of some

detrimental effect during consumer use of the product. Furthermore, presence of certainhydrocarbons or certain types of hydrocarbons may lower the quality of a specific product.

It was mentioned that aromatics are removed from kerosene by SO , extraction. The

aromatics have undesirable burning characteristics and hence the product quality is

improved if these "impurities" are removed. Lube oil treating process such as dewaxing,

deasphalting, and phenol treating also fall into this category.

The fourth basic category is blending of the finished cuts into commercially

saleable products such as motor gasoline, kerosene, lubricating oils, and bunker fuel oil,

according to their specifications.

These four basic categories encompass the fundamental operation of a refinery. All

other activities are carried out to implement them. The specifications for a given product

are established to insure a satisfactory level of product performance. Specifications can

be altered from time to time, but a product normally must meet the then existing product

specifications. Various crudes on the other hand yield fractions with significantly different

properties.

At first glance, it might appear reasonable to select crudes to best match the

product needs of each refinery. Many times, however, this is not economical as the

money saved in eliminating various conversions and treating processes is offset by other

factors. These might include crude availability, price, and transportation or specialty

product requirements. A refinery is a sophisticated multi-component process operated in

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overall balance. The balance is set by economic considerations with the major variables

being crude oil, process costs, and final products. It is thus easier to see why:

No two refineries are exactly alike.

Various conversion and purification processes are required.

Crude selection is important.

QUESTIONS 1v

1. How many basic areas can the petroleum refining operations be seperated into?

2. What is the purpose of treating process?3. Which workshops belong to decomposition process?

4. What is the overall balance in refinery?

5. How many categories of petroleum refining are classified into?

6. Why are no two refineries exactly alike?

Main Ideas 1

Write main ideas of reading 2

3.1 Find the word in the text which is closest in meaning to:

Fractionation fraction treating LPG refinery impurities sweetening process saleable

products.

3.2 Gap-filling

Complete the passage with appropriate words below.

Tail gas thermal cracking vacuum distillation visbreaking sulfurization stripping scrubbing reflux quench oil feedstock

1.. stock from which material is taken to be fed (charged) into a processing

unit.

2. oil injected into a product leaving a cracking or reforming heater to lower

the temperature and stop the cracking process.

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3..the portion of the distillate returned to the fractioning column to assist in

attaining better separation into desired fraction.

4..purification of a gas or liquid by washing it in a tower.

5 the removal (by steam-induced vaporization or flash evaporation) of the

more volatile components from a cut or fraction.

6 combining sulfur compounds with petroleum lubricants.

7. .viscosity breaking is a low temperature cracking process used to reduce

the viscosity or pour point of straight-run residuum.

8the distillation of petroleum under vacuum which reduces the boiling

temperature sufficiently to prevent cracking or decomposition of the feedstock

9. .the breaking up of heavy oil molecules into lighter fractions by the use of

high temperature without the aid of catalysts

10..the lightest hydrocarbon gas released from a refining process.

3.3 Decide whether the following statements are true (T) or false (F).

1. The petrochemical Industry is a renewable energy and sustainability

2. The hydrodesulfurization of diesel fuel is the process that the sulfur compounds are

cracked.

3. Synthesis gas is the mixture of hydrogen and carbon monoxide.

4. The sweetening process transforms the mercaptans to organic disulfides without

objectionable.

5. An aromatic-rich mixture can be made from catalytic reforming and crackingprocesses.

6. Vietnam is in OPEC and ASEAN.

7. A refinery is set by economic considerations with the major variables being crude

oil, process costs, and final products.

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Reading 3: Dzung Quat refinery

Dzung Quat Refinery Project Management Board has been established to build

and operate a grass roots refinery and associated facilities at Dzung Quat, Quang Ngai, a

central province of Vietnam.

Dzung Quat Refinery Project Management Board belongs directly to Vietnam Oil

and Gas Corporation (Petrovietnam) and was established by the PetroVietnam Directors

-

Refinery Project Management Board is authorized to deal with the organization,

management and implementation of the Dzung Quat Refinery Project.

The Project Site consists of four main areas: the refinery, the product tank farm,

the marine loading facilities at the jetty and the SPM and seawater intake and outfall

facilities. These areas are joined by interconnecting piping with an adjacent service road.

The refinery is designed to operate on two feedstocks:

o Million Tonnes per Annum of Bach Ho Crude (Sweet Case)

o 5.5 Million Tonnes per Annum of Bach Ho and 1.0 Million tonnes per annum

of Dubai crude (Sour Case)

The refinery is designed to produce the following products;

Domestic LPG

Polymer Grade Propylene

90/92/95 RON Gasoline pool

Burning Grade Kerosene

Jet A1Auto Diesel

Fuel Oil.

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Fig 1. Process units of Dzung Quat refinery

ABBREVIATIONS :

Single Point Mooring (SPM)

Crude Distillation Unit (CDU)

Naphtha Hydrotreater (NHT)

Izomerization Unit (ISOMER)

Continuous Catalytic Reformer (CCR)

Kerosene Treating Unit (KTU)

Residue Fluidised Catalytic Cracker (RFCC)

RFCC Naphtha Treating Unit (NTU)

LCO Hydrotreating Unit (LCO-HDT)

LPG Treating Unit (LTU)

Light Gasoil (LGO)

Heavy Gasoil (HGO)

Propylene Recovery Unit (PRU)

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Amine Regeneration Unit (ARU)

Sour Water Stripper (SWS)

Caustic Neutralisation Unit (CNU)Sulphur Recovery Unit (SRU)

The refinery (fig 1) will also have its own utility and power production systems.

Crude feedstock will be unloaded via a single point mooring and stored in the crude tank

farm. Some intermediate refinery tankage is provided within the refinery fence, however,

finished products are stored in a separate product tank farm. Product loading facilities will

be provided for both Ocean and Coastal ships. Truck loading will also be provided for

supply local to the refinery.

Dzung Quat Refinery has been applying "State of the Art" technologies licensed by

UOP (USA), Merichem (USA) and IFP (France) in numerous processes in the Refinery.

These advanced technologies are as follows:

UOP Advanced technologies in Naphtha HydroTreating Unit - CCR Platforming

Unit (NHT-CCR) to upgrade the straight run naphtha input produced in CDU to reformate

for using as gasoline blending stock. In addition, the unit will produce a hydrogen rich net

gas and LPG which will be sent to the LPG Treating Unit. The UOP integrated design willprovide high reliability, excellent product yield and completed catalyst regenerability with

minimum maintenance requirements.

The Residue Fluidized Catalytic Cracking Unit (RFCC) uses R2R technology

of IFP to convert residue produced in CDU to various valuable products, such as fuel gas,

LPG, naphtha for gasoline blending, diesel blending components, and fuel oil. The

process unit consists in feed injection system, riser, riser outlet separator system,

disengager/stripper, first stage regenerator, second stage regenerator, catalyst cooler,catalyst withdrawal well, catalyst transfer lines and control systems. The R2R technology

possesses many design features to achieve flexibility of operation on a wide range of

feedstocks. It is intended to provide high yields of gasoline and distillate while minimizing

the production of coke and gas.

MERICHEM's FIBER-FILMTM Contactor technologies for Treating Processes in

KTU, LTU, NTU and CNU units of the Refinery to reduce H 2S and mercaptan level in LPG

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(LTU), naphtha (NTU) and kerosene (KTU) products and to neutralize, treat mixed

effluent caustics so that the resulting brine can be sent to a waste water treatment facility

and reconstitute, separate the naphthenic, phenolic, and other organic acids from thebrine (CNU). The process offers numerous advantages such as high mass transfer

efficiency, saving valuable plant space, and reducing capital expenditures applied to

caustic, acid or water treating needs for a more profitable processing operation.

Questions 2

1. How many units does Dzung Quat refinery have in fig.1?

2. How many major products are there?

3. What is the RFCC of IFP?

4. What are the difference between UOP and Merichem technlogies at Dzung Quat

refinery?

3.4 Match a word or phrase in A with its definition in B

A B

a. crude oil

b. alkylation

c. desalting

d. hydrodesulfurization

e. isomerization

f. straigh run gasoline

g. cracking

h. catalytic cracking

i. deasphalting

j. OCTANE number

1. Removal of mineral salts (most chlorides, e.g,

magnesium chloride and sodium chloride)from crude oil.

2. A naturally occurring hydrocarbon mixture,

generally in a liquid state, which may also

include compounds of sulfur, nitrogen,

oxygen, metals, and other elements.

3. A catalytic process in which the principal

purpose is to remove sulfur from petroleumfractions in the presence of hydrogen.

4. Gasoline produced by the primary distillation

of crude oil. It contains no cracked,

polymerized, alkylated, reformed or visbroken

stock.

5. The breaking up of heavy molecular weight

hydrocarbons into lighter hydrocarcnon

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molecules by the application of heat and

pressure, with or without the use of catalysts.

6. A process using sulfuric or fluoric acid as acatalyst to combine olefins (usually butylene)

and isobutane to produce a high-octane

product known as alkylate

7. The process of breaking up heavier

hydrocarbon molecules into lighter

hydrocarbon fraction by use heat and

catalysts

8. Process of removing asphaltic materials from

reduced crude using liquid propane to

dissolve nonasphaltic compounds.

9. A reaction that catalytically converts straight-

chain hydrocarbon molecules into branched

chain molecules of subtantially higher octane

number. The reaction rearranges the carbon

skeleton of a molecule without adding or

removing anything from the original material.

10. Any one of several numerical indicators

of resistance to knock obtained by comparison

with reference fuels in standardized engine or

vehicle tests.

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Unit 2

Gasification1. Reading 1

Gas purification, as discussed in this text, involves the removal of vapor-phase

impurities from gas streams. The processes which have been developed to accomplish

gas purification vary from simple once-through wash operations to complex multiple-step

recycle systems. In many cases, the process complexities arise from the need for

recovery of the impurity or reuse of the material employed to remove it. The primaryoperation of gas purification processes generally falls into one of the following five

categories:

1. Absorption into a liquid

2. Adsorption on a solid

3. Permeation through a membrane

4. Chemical conversion to another compound

5. Condensation

Absorption refers to the transfer of a component of a gas phase to a liquid phase in

which it is soluble. Stripping is exactly the reverse-the transfer of a component from a

liquid phase in which it is dissolved to a gas phase. Absorption is undoubtedly the single

most important operation of gas purification processes.

Adsorption , as applied to gas purification, is the selective concentration of one or

more components of a gas at the surface of a microporous solid. The mixture of adsorbed

components is called the adsorbate, and the microporous solid is the admrbent. The

attractive forces holding the adsorbate on the adsorbent are weaker than those of

chemical bonds, and the adsorbate can generally be released (desorbed) by raising the

temperature or reducing the partial pressure of the component in the gas phase in a

manner analogous to the stripping of an absorbed component from solution. When an

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adsorbed component reacts chemically with the solid, the operation is called

chemisorption and desorption is generally not possible.

Membrane permeation is a relatively new technology in the field of gas

purification. In this process, polymeric membranes separate gases by selective

permeation of one or more gaseous components from one side of a membrane barrier to

the other side. The components dissolve in the polymer at one surface and are

transported across the membrane as the result of a concentration gradient. The

concentration gradient is maintained by a high partial pressure of the key components in

the gas on one side of the membrane barrier and a low partial pressure on the other side.

Although membrane permeation is still a minor factor in the field of gas purification, it israpidly finding new applications.

Chemical conversion is the principal operation in a wide variety of processes,

including catalytic and noncatalytic gas phase reactions and the reaction of gas phase

components with solids. The reaction of gaseous species with liquids and with solid

particles suspended in liquids is considered to be a special case of absorption and is

discussed under that subject.

Condensation as a means of gas purification is of interest primarily for the

removal of volatile organic compounds (VOCs) from exhaust gases. The process consists

of simply cooling the gas stream to a temperature at which the organic compound has a

suitably low vapor pressure and collecting the condensate.

2. Definitions

1. Btu (British Thermal Unit): A unit of measurement for energy; the amount of

heat that is necessary to raise the temperature of one pound of water by 1F.

2. s.t.p : standard temperature and pressure (273.15 K and 1.013 x 10 5 Pa)

3. scf: standard cubic feet of gas (60 oF, 1 atm)

4. Mcf (thousand cubic feet): A unit of measure that is more commonly used in the

low volume sectors of the gas industry, such as stripper well production.

5. MMscf: million standard cubic feet of gas

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6. Bcf (billion cubic feet): Gas measurement approximately equal to one trillion

(1,000,000,000,000) Btus.

7. Quad: An abbreviation for a quadrillion (1,000,000,000,000,000) Btus; roughly

equivalent to one trillion (1,000,000,000,000) cubic feet, or 1 Tcf.

8. Tcf (trillion cubic feet): Gas measurement approximately equal to one quadrillion

(1,000, 000,000,000,000) Btus

9. 1 grain per 100 scf : 24.19 mg/m 3 (s.t.p)

10. 1/4 grain H 2S per 100 scf : 4 ppmv H 2S

11. Volume of 1 Ib mol of ideal gas at 60F and 1 atm : 379.5 scf

12. Volume of 1 kmol of ideal gas at s.t.p: 22.41 m 3

13. Gas constant : R = 1.986 Btu/lb mo1 oR = 8.314 J/mol K

Questions 1

1. What is the gasification?

2. How are the difference between adsorption and absorption?

3. What do the main factors affect to adsorption and absorption process?

4. How many catalogues of gas purification processes are classified into?

Gammar forcus

1. Active and passive

2. Condition tense

3. Reading 2. Compositions and Properties of Natural gas

Natural gas (marsh gas) is colorless, odorless, tasteless, shapeless, and often

quoted as being lighter than air, but this statement is not quite true and is qualified in

some special cases. It is gaseous at any temperature higher than -161C . When it is at its

natural state, it is not possible to see or smell natural gas. For safety reasons, an odorant

(a mercaptan, also called a thiol) is added to natural gas so that it can be smelled if there

is a gas leak. A mercaptan is a chemical odorant that smells a little like rotten eggs.

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Although the composition and properties of natural gas are presented elsewhere in

more detail , it is pertinent to give a brief overview here of the composition and properties

of natural gas. The primary component of natural gas is methane (CH 4), and it also

contains gaseous hydrocarbons such as ethane (C 2H6), propane (C 3H8), and butane

(C4H10) as well as other non-hydrocarbon gases. In fact, natural gas is the primary market

source of the valuable rare gas helium (He), which is used in cryogenics, as a deep-sea

breathing gas, for inflating balloons and airships, and as a protective gas for many

industrial purposes, such as arc welding. Inhaling a small amount of helium temporarily

changes the quality of a persons voice, but caution must be exercised because helium isan asphyxiant.

Gas with a significant amount of sulfur impurities, such as hydrogen sulfide, is

termed sour gas or acid gas, and must be cleaned before consumption. Processed

natural gas available to end-users is tasteless and odorless, however, before gas is

distributed to end-users, it is odorized by adding small amounts of thiols (sulfur-containing

compounds having the general formula R-SH) to assist in leak detection. Natural gas can

also be hazardous to life and property through an explosion and/or asphyxiation. Forexample, if natural gas leaks go undetected (hence the reason for adding odorants such

as thiols), fireball- type explosions can result. In addition, natural gas, being an

asphyxiant, can kill organisms (including humans) if it displaces air to the point where the

oxygen content of the surrounding atmosphere is insufficient to support life.

Natural gas is often stated to be lighter than air, but this is only partly true. In

comparison with air, the relative density of methane is lighter than the density of air and

tends to dissipate into the atmosphere. The other hydrocarbon constituents of natural gashave a higher density than air and, therefore, do not dissipate into the atmosphere but will

collect on the ground. Being colorless (invisible) and odorless, the hydrocarbons can pose

a danger to life in the immediate vicinity either through asphyxiation or explosion.

When natural gas (i.e., methane) is confined, such as within a house or any

building, gas concentrations can reach explosive mixtures and, if ignited, result in

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destructive blasts. Methane has a lower explosive limit of 5% in air, and an upper

explosive limit of 15%.

By definition, the lower explosive limit of a gas or vapor at ordinary (ambient)

temperature is the percent by volume of the gas vapor in air and is the lower limit at which

the gas explodes or inflames. Conversely, the upper explosive limit of a gas or vapor at

ordinary (ambient) temperature is the percent by volume of the gas vapor in air and is the

upper limit at which the gas explodes or inflames. Similarly, the lower flammability limit is

the minimum concentration by volume of a combustible substance that is capable of

propagating a flame under specified conditions and the upper flammability limit is the

maximum concentration by volume of a combustible substance that is capable ofcontinued propagation of a flame under the specified conditions.

However, these limits are to be used as a guide only, because under a variety of

other circumstances, methane and the other hydrocarbon constituents of natural gas are

explosive and flammable.

Questions 2

1. What are the properties of natural gas?2. What are the compositions of natural gas?

3. What is the purpose of adding mercaptan into natural gas?

4. How is the difference between the lower explosive limit and the lower flammability

limit?

5. Where can we find the limit (explosive or flammability) of gas?

4.1 Find the word in the text which is closest in meaning to:

Natural gas desorbed colorless mercaptan condensate ambient temperature sour gas the lower explosive limit quadrillion the lower flammability limit

4.2 Decide whether the following statements are true (T) or false (F).

1. Adsorption refers to the transfer of a component of a gas phase to a liquid phase in

which it is soluble.

2. The attractive forces holding the adsorbate on the adsorbent are chemical bonds.

3. A mercaptan is a compound in rotten eggs.

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5. Reading 3 Gas processing

Various types of processing plants have been used since the mid-1850s to extract

liquids, such as natural gasoline, from produced crude oil. However, for many years,

natural gas was not a desired fuel. Prior to the early 20 th century, most of it was flared or

simply vented into the atmosphere, primarily because the available pipeline technology

permitted only very short-distance transmission.

As the gas processing industry evolved, the natural gas received and transported

by the major intrastate and interstate mainline transmission systems in the United States

had to meet the quality standards specified by pipeline companies. These quality

standards vary from pipeline to pipeline and are usually a function of a pipeline systems

design, its downstream interconnecting pipelines, and its customer base. However, these

standards generally specify that the natural gas must:

1. Be within a specific Btu content range (1,035 Btu/ft 3, +/- 50 Btu)

2. Be delivered at a specified hydrocarbon dew-point temperature level (below

which any vaporized gas liquid in the mix will tend to condense at pipeline

pressure)

3. Contain no more than trace amounts of elements such as hydrogen sulfide,

carbon dioxide, nitrogen, water vapor, and oxygen

4. Be free of particulate solids and liquid water that could be detrimental to the

pipeline or its ancillary operating equipment

Gas processing equipment, whether in the field or at processing/treatment plants,

assures that these requirements can be met. While in most cases processing facilitiesextract contaminants and higher molecular weight hydrocarbons (natural gas liquids) from

the gas stream. However, in some cases, the higher molecular weight hydrocarbons may

be blended into the gas stream to bring it within acceptable Btu levels. Whatever the

situation, there is the need to prepare the gas for transportation and use in domestic and

commercial furnaces. Thus, natural gas processing begins at the wellhead and because

the composition of the raw natural gas extracted from producing wells depends on the

type, depth, and location of the underground deposit and the geology of the area,

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processing must offer several options (even though each option may be applied to a

different degree) to accommodate the difference in composition of the extracted gas (fig

2).

Fig 2. General schematic of gas processing.

In those few cases where pipeline-quality natural gas is actually produced at the

wellhead or field facility, the natural gas is moved directly to the pipeline system. In other

instances, especially in the production of non-associated natural gas, field or lease

facilities referred to as skid-mount plants are installed nearby to dehydrate (remove water)

and decontaminate (remove dirt and other extraneous materials) raw natural gas into

acceptable pipeline-quality gas for direct delivery to the pipeline system. The skids are

often specifically customized to process the type of natural gas produced in the area and

are a relatively inexpensive alternative to transporting the natural gas to distant large-

scale plants for processing.

Gas processing consists of separating all of the various hydrocarbons, non-

hydrocarbons (such as carbon dioxide and hydrogen sulfide), and fluids from the

methane. Major transportation pipelines usually impose restrictions on the make-up of the

natural gas that is allowed into the pipeline. That means that before the natural gas can

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be transported it must be purified. While the ethane, propane, butanes, and pentanes

must be removed from natural gas, this does not mean that they are all waste products.

Gas processing (gas refining) is necessary to ensure that the natural gas intended

for use is clean-burning and environmentally acceptable. Natural gas used by consumers

is composed almost entirely of methane, but natural gas that emerges from the reservoir

at the wellhead is by no means as pure. Although the processing of natural gas is in many

respects less complicated than the processing and refining of crude oil, it is equally as

necessary before its use by end users.

Raw natural gas comes from three types of wells: oil wells, gas wells, and

condensate wells. Associated gas, i.e., gas from petroleum wells, can exist separate from

oil in the formation (free gas), or dissolved in the crude oil (dissolved gas). Non-

associated gas, i.e., gas from gas wells or condensate wells is 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, hydrogen sulfide (H 2S), carbon dioxide, helium, nitrogen, and

other compounds. In fact, the associated hydrocarbons (natural gas liquids, NGLs) can bevaluable byproducts of natural gas processing. Natural gas liquids include ethane,

propane, butane, iso-butane, and natural gasoline, which are sold separately and have a

variety of different uses; including enhancing oil recovery in oil wells, providing raw

materials for oil refineries or petrochemical plants, and as sources of energy.

6. Gap-filling

Complete the passage with appropriate words below.

Fire point Gas cap Boiling point Dehydration Rich gas Dead crude oil

Non-associated natural gas Fuel cell technology Abiogenic gas Density

1. The temperature to which gas must be heated under prescribed conditions of the

method to burn continuously when the mixture of vapor and air is ignited by a specified

flame: ..

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2. .is the mass of a substance contained in a unit volume (mass divided by

volume).

3. Water removal from natural gas streams call..

4.. The gas trapped between the liquid petroleum and the impervious cap rock of

the petroleum reservoir.

5. Sometimes called gas well gas; produced from geological formations that

typically do not contain much, if any, crude oil, or higher boiling hydrocarbons (gas liquids)

than methane; can contain non-hydrocarbon gases such as carbon dioxide and hydrogen

sulfide.

6. A gaseous stream is traditionally very rich in natural gas liquids (NGLs)

7. The chemical interaction of natural gas and certain other metals, such as

platinum, gold, and other electrolytes to produce electricity.

8. .Crude oil in the reservoir with minimal or no dissolved associated gas; often

difficult to produce as there is little energy to drive it.

9. ..The temperature at which the vapor pressure of the substance is equal to

atmospheric pressure.

10. Gas formed by inorganic means:...

7. Match a word or phrase in A with its definition in B.

A B

a. Wet gas

b. Fischer-Tropsch

process

c. Raw natural gas

1. The measure of a fluids thickness, or how well it

flows.

2. Impure natural gas as delivered from the well and

before processing (refining).

3. Gas that occurs in tight sandstones, siltstones,

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d. Viscosity

e. Muds

f. Unconventional gas

g. Gas processing

h. Tail-gas treating

i. Brine

j. Compression

sandy carbonates, limestone, dolomite, and chalk

4. Used in drilling to lubricate the drilling bit in rotary

drilling rigs.

5. The preparation of gas for consumer use by removal

of the non-methane constituents; synonymous with gas

refining.

6. An aqueous solution of salts that occurs with gas

and crude oil; seawater and saltwater.

7. Removal of the remaining sulfur compounds from

gases remaining after sulfur recovery.

8. The catalytic process by which synthesis gas

(syngas; mixtures of carbon monoxide and hydrogen)

is converted to hydrocarbon products.

9. Reduction in volume of natural gas is compressed

during transportation and storage

10. Natural gas that contains considerable amounts of

higher molecular weight hydrocarbons other than

methane.

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References

1. T Vi , T xu

b k

2. T Vi , nh xu k

3. ASTM DICTIONARY OF ENGINEERING SCIENCE & TECHNOLOGY , Printed in

Mayfield, PA November 2005.

4. Arthul Kohl, Richard Nielsen, Gas purification , Gulf Publishing Company Houston,

Texas, 1997.

5. James G. Speight, Natural Gas A Basic Handbook , Gulf Publishing Company

Houston, Texas, 2007.

6. Industrial Organic Chemicals, Second Edition, by Harold A. Wittcoff, Bryan G.

Reuben, and Jeffrey S. Plotkin, 2009