ch # 1-introduction & history

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CHAPTER # 01 Introduction & History

INTRODUCTION & HISTORY

1.1. HISTORY Of CRUDE OIL:

Petroleum is a complex liquid mixture of organic compounds. It is generally

defined as an oily flammable bituminous liquid that may vary from almost

colorless to black, occurs in many places in the upper strata of the earth, is a

complex mixture of hydrocarbons with small amounts of other substances, and

is prepared for use as gasoline, naphtha, or other products by various refining

process.

The first recorded use of petroleum dates back over 5000 years ago when it was

recognized that the heavier derivatives of petroleum (asphalts) could be used

for caulking and as an adhesive for jewelry and construction purposes. There is

also documented use of asphalt for medicinal purposes. Approximately 2000

years ago, Arabian scientists developed methods for distillation of petroleum

which were introduced into Europe by way of Spain. Interest in petroleum was

also documented in china since petroleum was encountered when drilling for

salt and appears on documents of the third century A.D. The Baku region of

northern Persia was also reported (by Marco polo in 1271 1273) to have a

commercial petroleum industry. The interest in petroleum continued up to

modern times with an increasing in naphtha when it was discovered that this

material could be used as an illuminant and as a supplement to asphaltic

incendiaries for use during warfare. The naphtha of that time was obtained from

shallow wells or by the destructive distillation of asphalt. This can perhaps be

equated to the modern day cooking operations where the overall objective of

the process is to convert residue into liquid fuels.

The modern oil industry began in 1859 with the discovery and subsequent

commercialization of petroleum in Pennsylvania (Bell, 1945). After the

completion of first well (by Edurn Drake), the surrounding areas were

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CHAPTER # 01 Introduction & Historyimmediately leased and extensive drilling took place, (crude oil output in the

united states increased to approximately 10 million bbl in 1874.

In 1861 the first cargo oil, contained in wooden barrels, was sent across the

Atlantic to London, and by the 1870s refineries, tank cars, and pipelines had

become characteristic features of the industry. The end of the nineteenth

century was characterized by the opening up of the oil fields in the Far East.

At the outbreak of World War 1 in 1914, the two major producers were the

United States and Russia but supplies of oil were also being obtained from

Indonesia, Romania, and Mexico. During the 1920s and 1930s, attention was

also focused on other area for oil production such as the United States, the

Middle East, and Indonesia.

In the past 1945 era, Middle Eastern countries continued to rise in importance

because of new discoveries of vast reserves. The United States, though

continuing to be the biggest producer, was also the major consumer and thus

was not a major exporter of oil.

At present time, many countries are recognized have reserves of crude oil. At

current rates of production, proven oil reserves are sufficient for only 30 years

and more reserves need to be discovered to replace those being consumed. For

example, oil production from the organization of Petroleum Exporting

countries (OPEC) grew by more than 13 % during 1986 with Saudi Arabias

production increasing by some 45 % during the year. In the non-OPEC countries,

the decline in production was realized predominantly by the United States

where output decreased by 3 %.

In fact, according to these data, the U.S has less than 10 years of proven

reserves at the current rate of output compared with more than 90 years of

output in Saudi Arabia or an average of some 85 years of output at current

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CHAPTER # 01 Introduction & Historyproduction rates for the whole Middle Eastern countries. In addition, the United

States is one of the largest importers ofpetroleum. In summary, the world oil

consumption increased by 2.5 % in 1986 and reached 59.9 million bbl / day.

This is the highest rate of growth since 1978.

History of Petroleum Refining and Oil Field in Pakistan:

First oil well Kundal near Mianwali was drilled in 1866. In 1915, the first oil field

of Pakistan was discovered by Attock Oil Company, with the passage of time,

other fields such as Dakni, Dhalian, Joyamir, Balkser, Dhernal, Dhowdak, Toot,

Mianal, Badeen was discovered in Pakistan. Different oil companies are

searching for oil and gas such as PPL (Pakistan Petroleum Ltd), OGDC (OIL &

GAS Development Corporation), UNION TEXAS LASMO. The first oil refinery by

the name ofAttock oil refinery Ltd in Pakistan came on stream in 1922, with

capacity of 25000 bbl / day but the present capacity is about 40000 bbl / day.

Second oil Refinery (Pakistan Refinery Ltd) was started from 1962 whose

present capacity is about 50000 bbl / day. Third Oil refinery (National Refinery

Ltd) was established in 1963 whose capacity is about 65000 bbl / day. Pakistan

is importing crude oil from Saudi Arabia, Iran, United Arab Emirates, etc.

It is hoped that the dream of self sufficiency of Pakistan is production of oil will

be fulfilled (inshallah).

ORIGIN OF PETROLEUM:

Petroleum is by far the most commonly used liquid fuel source. Since there is a

wide variation in the properties of crude Petroleum, the proportions in which the

different fractions occur vary with origin. Thus some crude oils have higher

proportions of the lower boiling components where as others have higher

proportions of residuum (asphaltic components).

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CHAPTER # 01 Introduction & HistoryOf the several theories advanced concerning the origin of petroleum, the theory

of vegetal origin is the most widely accepted today, it holds that enormous

quantities of gelatinous vegetation accumulated in clays and sands along

seacoasts or lakes. Shifting currents then buried the organic material in layers

of sediment which protected it from the normal processes of decay.

Subsequent changes in the earth structure eventually subjected the entrapped

vegetal matter to enormously high pressures and temperatures which brought

about a type of semi

destructive distillation. This along with other metamorphic processes resulted

in the formation of petroleum.

Geologic studies indicate that petroleum that probably was not formed in the

pools where it is founds today. The deposits of crude petroleum were

undoubtedly formed near seashores, but the action of the surrounding water

gradually shifted the location of the oil pool. After a period of many centuries,

the oil was forced through layers of porous rock strata until it finally became

entrapped under a dome capped by hard rock. This made it impossible for the

gas or oil to escape, and the water kept the pool of oil under pressure.

PRODUCTION OF CRUDE OIL:

In drilling for oil, the oil retaining cap rock above the deposit is penetrated,

and the existing pressure forces the oil, gas, and some water to the surface. An

attempt is made to locate the bottom of the well at the richest part of the oil

bearing rock. This procedure makes it possible to keep out much of the water

which would otherwise come up with the oil and gas. As the petroleum is

removed from the underground deposit, the water moves in to take its place.

Eventually the material under pressure decreases to the point where it will no

longer force the oil and gas to the surface. When this occurs, gas or water may

be pumped back into the well to increase the pressure and force the crude oilfrom the pool.

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Under the natural pressure of the well, this may run to 1000 psi or higher, great

quantities of hydrocarbon vapors are absorbed in the liquid petroleum and

much liquid is held in suspension in the gases. As the crude and gas are

pumped from the well, they are passed through a separator or trap, where theliquid and the gases are separated. After a preliminary purification process in

a field treating plant, the crude oil is pumped through pipelines to the refinery.

This treating plant reduces the dirt and water in the crude oil to less than 3% so

as to minimize pipe-line troubles.

Types of crude oil:

Petroleum oils or crude oils are brownish green to black liquids composed

chiefly of carbon and hydrogen. They contain many thousands of individuals

compounds ranging from light

gases such as methane to heavy asphaltic materials to heavy asphaltic

materials that are solid when separated from the oil. Crudes are commonly

classified according to the residue from their distillation. This deposits on the

relative contents of three hydrocarbons namely paraffins, napthenes, and

aromatics.

1. Asphaltic Base:

Containing very little paraffin wax and a residual primarily as asphaltic

(Predominantly condensed aromatics). Sulphur, oxygen and nitrogen contents

are often relatively high. Light and intermediate fractions have high percentage

of napthenes. These crude oils are particularly suitable for making high quality

gasoline, machine oils and asphalt.

2. Paraffin Base:

Containing little or no asphaltic materials, are good sources ofparaffin wax,

quality motor lube oils and high grade kerosene. They usually have lower non-

hydrocarbon content than do the asphalt base crudes.

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CHAPTER # 01 Introduction & History3. Mixed Base:

Containing considerable amounts of both wax and asphalt. Virtually all

products can be obtained, although at lower yields than from the two classes.

COMPOSITION OF CRUDE OIL (PETROLEUM):

Crude oil has physical and chemical characteristics that vary widely from one

production field to another and even within the same field. The roughest form of

characterization is the classification of light and heavy crude.

Because crude oil is composed essentially of hydrocarbon molecules plus

organic compounds of Sulphur, oxygen and nitrogen as well as compounds

containing metallic constituents, particularly vanadium, nickel, iron and copper.

Crude oil specific gravity varies

inversely with its H/C atomic ratio, and for various crude oils specific gravities

will range from 0.7 to 1.0; they are often expressed in degrees API (American

Petroleum Institute) which will vary between 70 and 5.

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Figure: Principal Petroleum Products, their boiling range

temperatures and their number of carbon atoms.

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OIL REFINERY:

Raw or unprocessed crude oil is not generally useful. Although light, sweet

(low viscosity, low sulfur) crude oil has been directly as a burner fuel for steam

vessel propulsion, the lighter elements form explosive vapors in the fuel tanks

and are therefore hazardous, especially in warships. Instead, the hundreds of

different hydrocarbon molecules in crude oil are separated in a refinery into

components which can be used as fuels, lubricants and as feedstock in

petrochemical processes that manufacture such products as plastics,

detergents, solvents, elastomers, and fibers such as nylon and

polyesters.

Petroleum, fossil fuels are burned in internal combustion engines to provide

power for ships, automobiles, aircraft engines, lawn movers, chainsaws and

other machines. Different boiling points allow the hydrocarbons to be separated

by distillation. Since the lighter liquid products are in great demand for use in

internal combustion engines, a modern refinery will convert heavy hydrocarbons

and lighter gaseous elements into these higher value products.

Oil can be used in a variety of ways because it contains hydrocarbons of varying

molecular masses, forms and lengths such as paraffins, aromatics,

naphthenes (or cycloalkanes), alkenes, dienes, alkynes while the molecules

in crude oil include different atoms such as sulfur and nitrogen, the

hydrocarbons are the most common form of molecules, which are molecules of

varying lengths and complexity made of hydrogen and carbon atoms, and a

small number of oxygen atoms. The differences in the structure of these

molecules account for their varying physical and chemical properties, and it is

this variety that makes crude oil useful in a board range of applications.

Once separated and purified of any contaminants and impurities, the fuel or

lubricant can be sold without further processing. Smaller molecules such as

isobutene and propylene or butylenes can be recombined to meet specific

octane requirements by processes such as alkylations, or less commonly,

dimerization. Octane grade of gasoline can also be improved by catalytic1-8


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CHAPTER # 01 Introduction & Historyreforming, which involves removing hydrogen products such as aromatics.

Intermediate products such as gasoils can be reprocessed to break heavy,

long-chained oil into a lighter short-chained one, by various forms ofcracking

such as fluid cracking, thermal cracking, and hydrocracking. The final step in

gasoline production is the

blending of fuels with different octane ratings, vapor pressures, and other

properties to meet product specifications.

-Oil refineries are large scale plants, processing about a hundred thousand to

several hundred thousand barrels of crude oil a day. Because of the high

capacity, many of the units operate continuously, as opposed to processing in

batches, at steady state or nearly steady state for

months to years. The high capacity also makes process optimization and

advanced process control very desirable.

Major Products:

Major products are usually grouped into three categories: light distillates (LPG,

gasoline, and naphtha), middle distillates (kerosene, diesel), heavy distillates

and residuum (heavy fuel oil, lubricating oils, wax, and asphalt).

This classification is based on the way I think snakes mate oil is distilled and

separated into fractions (called distillates and residuum) as in above drawing.

Liquid petroleum gas (LPG)

Gasoline (also known as Petrol)

Naphtha

Kerosene and related jet aircraft fuels.

Diesel fuel

Fuel oils

Lubricating oils

Paraffin wax

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CHAPTER # 01 Introduction & History Asphalt and tar

Petroleum coke

Common units:

Desalter unit washes out salt from the crude oil before it enters the

atmospheric distillation unit.

Atmospheric distillation unit distills crude oil into fractions.

Vacuum distillation unit further distills residual bottoms after

atmospheric distillation.

Naphtha hydrotreater unit uses hydrogen to desulfrize naphtha from

atmospheric distillation. Must hydro treat the naphtha before sending to a

catalytic reformer unit.

Catalytic reformer unit is used to convert the naphtha-boiling range

molecules into higher octane reformate (reformer product). The reformate

has higher content of aromatics and cyclic hydrocarbons. An important by

product of a reformer is hydrogen released during the catalyst reaction. The

hydrogen is used either in the hydrotreaters or the hydrocracker.

Distillate hydrotreater unit desulfrizes distillates (such as diesel) after

atmospheric distillation.

Fluid catalytic cracker (FCC) unit upgrades heavier fractions into

lighter, more valuable products.

Hydrocracker unit uses hydrogen to upgrade heavier fractions into

lighter, more valuable products.

Visbreaking unit upgrades heavy residual oils by thermally cracking

them into lighter, more valuable reduced viscosity products.

Merox unit treats LPG, kerosene or jet fuel by oxidizing mercaptans to

organic disulfides.

Cooking units (delayed cooking, fluid Coker, and flexicoker) process

very heavy residual oils into gasoline and diesel fuel, leaving petroleum cokeas a residual product.

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CHAPTER # 01 Introduction & History Alkylation unit produces high-octane component for gasoline

blending.

Dimerization unit converts olefins into higher-octane gasoline

blending components. For example, butanes can be dimerized into isooctane

which may subsequently be hydrogenated to form isooctane. There are alsoother uses for Dimerization.

Isomerization unit converts linear molecules to higher-octane

branched molecules for blending into gasoline or feed to Alkylation units.

Steam reforming unit produces hydrogen for the hydrotreaters and

hydrocracker.

Liquefied gas storage units for propane and similar gaseous fuels at

pressure sufficient to maintain in liquid form. These are usually spherical

vessels or bullets (horizontal vessels with rounded ends.

Storage tank for crude oil and finished products, usually cylindrical,

with some sort of vapor emission control and surrounded by an earthen berm

to contain spills.

Amine gas treater, Claus unit and tail gas treatment for converting

hydrogen sulfide from hydrodesulphurization into elemental sulfur.

Unity units such as cooling towers for circulating cooling water, boiler

plants for steam generation, instrument air systems consisting of API

separators, dissolved air flotation (DAF) unit and some type of further

treatment (such as an activated sludge biotreater) to make such water

suitable for reuse or for disposal.

Solvent refining units use solvent such as cresol or furfural to

remove unwanted, mainly asphaltenic materials from lubricating oil stock (or

diesel stock).

Solvent dewaxing units remove the heavy waxy constituents

petrolatum from vacuum distillation products.

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Crude Oil:

The word CRUDE means Rock, so as evidence from name, the oil obtained

from Rock is crude oil.

A Mixture of various hydro carbons believed to be formed by Decay and

Decomposition of Marine animals as well as Prehistoric forest under Earth

crust at High Pressure and Temperature millions of years ago.

The crude oil contains hundreds of different hydrocarbons, present in

different proportions and each has its own characteristics/properties.

The crude oil also contains small quantities of water and salts depending on

the source it extracted.

General Composition of Crude:

Types of Crude (w.r.t. Gravity):

Light Crude :

The Crude having gravity less than 0.86 or which contains more quantity of

lighter fractions.

Heavy Crude :

The crude having gravity 0.86 or greater is called heavy crude or which

contains heavier fractions.

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Types of Crude (w.r.t. Sulfur):

Sweet Crude :

The Crude having sulfur contents less than 0.5 ppm.

Sour Crude :

The crude having sulfur contents 0.5 ppm or more.

Types of Crude (w.r.t. Components):

Paraffinic Crude :

Crude which contains paraffinic wax type residue.

Asphaltic Crude :

Crude which contains more asphatic components in its residue. This crude is

used for making Bitumen/Asphalt.

Types of Crude:

Salty Crude :

The crude having salts greater than 1 PTB is called salted crude.

Impurities in Crude:

Impurities refer to the Undesirable components in crude which

creates/can create problem in plant hardware when crude is processed.

Removal of these impurities is necessary.

Impurities includes salts ofCa & Mg, sand, slit, drilling mud, iron oxide

& sulfide, leaves, trashes, water, sulfur, metals like Ni, Fe, As and Naphthenic

acids.

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NAPHTHA:

Naphtha is a general term used to describe special boiling point spirits having aboiling range of approximately 30 to 180 oC. As it has all boiling ranges,

therefore, it is usually called as Full Boiling Range Naphtha (FBRN).

Naphtha or FBRN is widely used in petrochemical industries as a feed stock. It is

a highly volatile product, manufactured from crude oil by direct atmospheric

distillation and by catalytic cracking of heavy residues.

COMPOSITION OF NAPHTHA:

Naphtha essentially consists of following hydrocarbon compounds, namely;

1. Paraffins

2. Olefins

3. Naphthenes4. Aromatics

1. PARAFFINS (Alkanes):

Paraffins are further divided into three categories, these are;

n-paraffins

Iso-paraffins Branched paraffins

n-paraffins:

The straight chain hydrocarbons are normally called as n-paraffin. All normal

paraffin hydrocarbons from C1-C33 have been isolated from petroleum or crude

oil.

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CHAPTER # 01 Introduction & HistoryCH3-CH2-R

Iso-paraffins:

The hydrocarbons having a methyl group on the number two (2) carbon atom of

n-paraffin, such hydrocarbons are known to be Iso-paraffins.

CH3

CH3-CH3-CH3-R

*R is usually a methyl group (CH3).

Branched Paraffins.

These hydrocarbons have an alkyl group or groups usually methyl further down

the carbon chain.

CH3

CH3-CH2-CH-R

2. OLEFINS:

These are unsaturated hydrocarbon compounds and their presence in Naphtha

would lead to:

a) Possible gum formation in presence of airb) Increased coking in the pre-heater tubes of the hydro-desulphurization

section

c) Increased hydrogen consumption in the hydro-desulphurization section

Therefore, the olefin content in Naphtha is kept to the minimum and inmanufacturing specifications. It is limited to maximum 1% on volume basis. The

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CHAPTER # 01 Introduction & Historythree most important olefins used for the production of petrochemicals are

ethylene, propylene and butadiene.

The removal of olefins from the naphtha feed is very essential as they exhibit

highly exothermic reaction during their removal from the naphtha feed. It is to

be carefully noticed

that in straight run naphthas the olefin contents are nil, where as cracked

naphthas contains olefin contents.

a) Linear Olefins:

C-C-C-C = C-C

b) Cyclic Olefins:

3. NAPHTHENES:

These are saturated cyclic hydrocarbons, many of which have methyl groups.

These are also named as Cyclo-paraffins. The lower boiling petroleum fractions

contain appreciable quantities of cyclo-pentanes and cyclo-hexanes. The

presence of a high percentage of cyclo-pentanes and cyclo-hexanes in a

gasoline is important because they are precursors of aromatic hydrocarbons.

The dehydrogenation of cyclo-hexane and methyl-cyclo-hexane to benzene and

toluene respectively, and the isomerization followed by the dehydrogenation of

methyl-cyclo-pentane and di-methyl-cyclo-pentane to benzene and toluene are

the major reactions in the catalytic reforming of straight run gasoline.

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C

C

C

C

C

C

C

C

C

C

C

CH3

C CH R

C C

C

CC


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Alkyl-cyclo-pentanes Alkyl-cyclo-hexane

R is usually methyl group (CH3)

PROPERTIES:

To obtain the product known as naphtha, a complex soup of chemicals is

broken into another range of chemicals, which are then graded and isolated

mainly by their specific gravity and volatility. As a result, the product contains a

range of distinct chemicals with a range of properties. They generally have a

molecular weight range of 100-215, a specific gravity range of 0.75-0.85, and a

boiling point range of 70-430 F. Their vapor pressure is usually less than 5 mm

mercury.

Naphthas are insoluble in water. They are colorless (with a kerosene odor) orred-brown (with an aromatic odor). They are incompatible with strong oxidizers.

Generally speaking, less dense naphthas ("light naphthas") have a

higher paraffin content. They are therefore also calledparaffinic naphtha.

The denser naphthas ("heavy naphthas") are usually richer in Naphthenes and

aromatics, and they are therefore referred to as N&A's.

USES:

Paraffinic (or light) naphthas:

The main application for paraffinic ("light") naphthas is as feedstock in the

petrochemical production of olefins. This is also the reason they are sometimes

referred to as "light distillate feedstock" or LDF. (These naphtha types may

also be called "straight run gasoline" (SRG) or "light virgin naphtha" (LVN).)

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CHAPTER # 01 Introduction & HistoryWhen used as feedstock in petrochemical steam crackers, the naphtha is

heated in the presence of water vapor and the absence of oxygen or air until

the hydrocarbon molecules fall apart. The

primary products of the cracking process are olefins (ethylene / ethene,

propylene / propene and butadiene) and aromatics (benzene and toluene).

These are used as feedstock for derivative units that

produce plastics (polyethylene and polypropylene, for example), synthetic fiber

precursors (acrylonitrile), and industrial chemicals (glycols, for instance).

Heavy naphthas:

The "heavy" naphthas can also be used in the petrochemical industry, but they

are more often used as feedstock for refinery catalytic reformers where they

convert the lower octane naphtha to a higher octane product called reformate.

Alternative names for these types are "straight run benzene" (SRB) or "heavy

virgin naphtha" (HVN).

ADDITIONAL APPLICATIONS:

Naphthas are also used in other applications, such as:

In the production ofgasoline.

In industrial solvents and cleaning fluids

An oil painting medium

The sole ingredient in the home cleaning fluid Energize, which has been

discontinued. You can purchase this type of naphtha at any hardware store.

An ingredient in shoe polish

An ingredient in some lighter fluids for wick type lighters such as Zippo

lighters.

An adulterant to petrol

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CHAPTER # 01 Introduction & History A fuel for portable stoves and lanterns, sold in North America as white

gas or Coleman fuel.

Historically, as a probable ingredient in Greek fire (together with grease,

oil, sulfur, and naturally occurring saltpeter from the desert).

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ch # 1-introduction & history

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