Principles of petroleum refining

*Origin of petroleum


*Refinery stocks


*CLASSIFICATION OF PETROLEUM




*CRUDE OIL PROPERTIES


*COMPOSITION OF PETROLEUM


*Octane Number


*MANUFACTURING PROCESSES

Principles of petroleum refining

6:31:00 PM Oil Refinery : Description - Definitions

Oil and Natural Gas

Every day on Earth we burn: 15.9 million tons of coal, 82.4 million barrels of oil & 7.4 billion m3 of natural gas.

The U.S. consumes 20 million barrels of oil/DAY. (42 gallons/barrel – 840 million gal/day)

100 tons of ancient plant life is required to create 1 gallon of gasoline

Each year humans have required several centuries of sunlight to keep the economy going.

Ex 1997 = 422 years worth

The 20 richest countries use 80% of the natural gas, 65% of the oil & 50% of the coal produced/yr.

The U.S. with less than 1/20th world’s population uses more than ½ of the commercial energy supply.

Fossil fuels provide 85% of all commercial energy in the world.

Industrial 36.5%

Mining, milling, smelting, & forging of primary metals consume ¼ of industrial energy.

Chemical industry is 2nd 

Remainder is raw material for plastics, fertilizers, solvents, lubricants & others.

Manufacture of cement, glass, bricks, tile, paper & processed foods also consume large amounts.

COAL

Transportation (26%) – 98% from petroleum products & 2% natural gas & electricity

75% of transport energy is used by motor vehicles.

Nearly 3 trillion passenger miles & 600 billion ton miles of freight are carried annually by motor vehicles in the U.S.

Much is very inefficient: Taking a 2,000 kg car to transport one 60 kg person a few km to work or shopping isn’t a wise use of resources.

COAL FORMATION

A variety of industries use coal's heat and by-products. Separated ingredients of coal (such as methanol and ethylene) are used in making plastics, tar, synthetic fibers, fertilizers, and medicines.

Coal is also used to make steel. Coal is baked in hot furnaces to make coke, which is used to smelt iron ore into iron needed for making steel. It is the very high temperatures created from the use of coke that gives steel the strength and flexibility for things like bridges, buildings, and automobiles.

The concrete and paper industries also use large amounts of coal.

PROBLEMS:

Mining dangers: Cave-ins, fires, accidents & accumulation of poisonous or explosive gasses. Health hazards including black lung disease.

The Sago Mine Disaster was a coal mine explosion on January 2, 2006, in the Sago Mine in Sago, West Virginia, USA near the Upshur County seat of Buckhannon, West Virginia. The blast and ensuing aftermath trapped thirteen miners for nearly two days. Only one miner survived. It was the worst mining disaster in the U.S. since a 2001 tragedy in Alabama killed 13, and the worst in West Virginia since a 1968 event that took 78 lives.

Environmental degradation: Strip mining removes vegetation & soil. Mine tailings leach into water.

Mountaintop removal/valley fill strip mining is relentlessly consuming Kayford Mountain in southern West Virginia. 

Mine tailings in the Savage River.

Mountaintop removal/valley fill strip mining is relentlessly consuming Kayford Mountain in southern West Virginia.

The combustion of coal produces several types of emissions that adversely affect the environment. The five principal emissions associated with coal consumption in the energy sector are:

Sulfur dioxide (SO2), which has been linked to acid rain and increased incidence of respiratory illnesses

Nitrogen oxides (NOx), which have been linked to the formation of acid rain and photochemical smog and to depletion of the Earth’s ozone layer

Particulates, which have been linked to the formation of acid rain and increased incidence of respiratory illnesses

Carbon dioxide (CO2), which is the primary greenhouse gas emission from energy use.

Mercury, which has been linked with both neurological and developmental damage in humans and other animals. Mercury concentrations in the air usually are low and of little direct concern. However, when mercury enters water — either directly or through deposition from the air — biological processes transform it into methylmercury, a highly toxic chemical that accumulates in fish and the animals (including humans) that eat fish.

Americans consume almost 21 million barrels of oil a day, a quarter of the world total of 84 million barrels a day, reports the International Energy Agency. But China is now second at 6.4 million barrels a day, and its demand could double by 2020.

OIL FORMATION:

Oil is the lifeblood of America’s economy.  Currently, it supplies more than 40% of our total energy demands and more than 99% of the fuel we use in our cars and trucks. The Department of Energy’s Office of Fossil Energy focuses on two important concerns over oil - an immediate readiness to respond to oil supply disruptions and keeping America’s oil fields producing in the future.

1. Ocean creatures die and are buried in sediments.

2. Organic material must be heated to a certain temperature (100 to 135 C) . This occurs when the sediments get pushed downward between 10,000 and 13,000 ft. below sea level. Known as the “kitchen” it is hot enough to boil the sediments into petroleum.

Too deep and the sediments will be cracked into gas or destroyed. Too shallow – not high enough for “cooking”.

3. Surrounding rock must be permeable for the material to move through yet topped by a cap rock of impermeable rock.

4. Cooking takes millions of years.

 A 42-U.S. gallon barrel of crude oil provides slightly more than 44 gallons of petroleum products. This gain from processing the crude oil is similar to what happens to popcorn, which gets bigger after it's popped. The gain from processing is more than 5%.

One barrel of crude oil, when refined, produces about 19 gallons of finished motor gasoline, and 10 gallons of diesel, as well as other petroleum products. Most petroleum products are used to produce energy. For instance, many people across the United States use propane to heat their homes.

Other products made from petroleum include:

Ink

Crayons

Bubble gum

Dishwashing liquids

Deodorant

Eyeglasses

CDs and DVDs

Tires

Ammonia

Heart valves

Nearly all of these byproducts have negative impacts on the environment and human health: 

Carbon dioxide is a greenhouse gas and a source of global warming.1

SO2 causes acid rain, which is harmful to plants and to animals that live in water, and it worsens or causes respiratory illnesses and heart diseases, particularly in children and the elderly.

NOX and VOCs contribute to ground-level ozone, which irritates and damages the lungs.

PM results in hazy conditions in cites and scenic areas, and, along with ozone, contributes to asthma and chronic bronchitis, especially in children and the elderly. Very small, or “fine PM” is also thought to cause emphysema and lung cancer.

Lead can have severe health impacts, especially for children, and air toxics are known or probable carcinogens. 

PROBLEMS

Environmental damage due to drilling & spilling. In 1989 Exxon Valdez spilled 10.8 million gallons of oil. Such disasters only account for 5% of the oil polluting oceans. Most comes from small oil tanker accidents & leaks, offshore oil rig leaks & oil leaks on land.

Pro drilling: (California coast, Beaufort Sea, Grand Banks & ANWR) An inexpensive, plentiful energy supply, even if only for a few decades, is worth the social & environmental costs.

Even if work began on ANWR today (January 2007), its benefits are years away. Current Department of Energy estimates are that the soonest ANWR production could begin is in 2015 and would not peak until 2024.

ANWR could help improve U.S. crude oil supply, but would still only make up a small fraction of U.S. oil demand. The U.S. Department of Energy projects peak ANWR production at 780,000 barrels per day after 2024. That represents only 3.7% of current U.S. consumption and about 3% of projected demand in 2024.

The U.S. Department of Energy projects a decline of 79 cents per barrel (1.9 cents per gallon) for crude oil prices as a result of peak ANWR production in 2024. Crude oil prices are currently about $70 per barrel. If ANWR were producing at peak today, we would see a price decrease of slightly more than 1%.

Natural Gas

23% of Global Energy Consumption & growing rapidly.

Convenient, cheap, clean burning (1/2 the amount of CO2 as coal)

Difficult to ship across oceans or store in large quantities.

Current global consumption will be use up known supplies in 60 years.

U.S. = 6% = 10 yr. Supply at current rate of consumption.

We can also use machines called digesters that turn today's organic material (plants, animal wastes, etc.) into natural gas.  This replaces waiting for thousands of years for the gas to form naturally.

Natural gas is used to produce steel, glass, paper, clothing, brick, electricity and as an essential raw material for many common products. Some products that use natural gas as a raw material are: paints, fertilizer, plastics, antifreeze, dyes, photographic film, medicines, and explosives.

Slightly more than half of the homes in the United States use natural gas as their main heating fuel. Natural gas is also used in homes to fuel stoves, water heaters, clothes dryers, and other household appliances.

Problems with natural gas:

1. The combustion of natural gas emits almost 30 percent less carbon dioxide than oil, and just under 45 percent less carbon dioxide than coal.

One issue that has arisen with respect to natural gas and the greenhouse effect is the fact that methane, the principle component of natural gas, is itself a very potent greenhouse gas. In fact, methane has an ability to trap heat almost 21 times more effectively than carbon dioxide.

2. Natural gas emits virtually no sulfur dioxide, and up to 80 percent less nitrogen oxides than the combustion of coal, increased use of natural gas could provide for fewer acid rain causing emissions.

3. Leaks in transmission and highly explosive. (Mercaptan  added to give it a smell.)

4 . Only about 11 years left at current use.

Oil and Natural Gas

4:38:00 PM Oil Refinery : Description - Definitions

Octane Number O.N.

Gas station pump offering five different octane ratings.The octane rating is a measure of resistance to gasoline and other fuels to blow up (engine knocking) in spark ignition internal combustion engines. High-performance engines typically have higher compression ratios and are therefore more likely to blow up, so they require higher octane fuel. A decline in performance does not drive better performance in general with the high-octane fuel, where the compression ratio is fixed through the design of the engine.

Measured by the number of octane fuel in the engine test, known by comparison with a mixture of heptane iso-octane and normal, which will have the same ability of anti-hit as fuel under test: the percentage, by volume, of the ISO - octane in the mix is ​​the octane rating of fuel. For example, the gasoline with the same knocking characteristics as a mixture of 90% ISO-octane and heptane have 10% of 90 octane.  because some fuels are more resistant to a variety of ISO - octane, has been expanded to allow the definition of the octane numbers higher than 100.

Definition of octane

The octane rating of the engine spark and fuel resistance is the bomb (an anti-knock rating) compared with a mixture of ISO - octane (2,2,4 - trimethylpentane, an isomer of octane) and n heptane. By definition, is set to ISO-octane octane rating of 100 and heptane is assigned to the octane rating of zero. And 87 octane gasoline, for example, have the same anti-knock rating of a mixture of 87% (by volume) ISO - octane and 13% (by volume) n heptane. This does not mean, however, that the gasoline actually contains these hydrocarbons in these proportions. It simply means that it may blow up the resistance and the same mixture described.

Octane is not related to the energy content of fuel (see heating value). It is only a measure of the tendency of fuel to burn rather than explode.

Measurement methods

The most common type of octane in all parts of the world and the Research Octane Number (RON). RON is determined by running the fuel in the engine test with a compression ratio under changing conditions of control, and compared the results with those of a mixture of ISO - octane and n heptane.

There is another type of octane rating, called Motor Octane Number (two) or lean rating octane aviation, a better measure of how the fuel behaves when under load. Two test engine uses a test similar to those used in testing the RON, but with a preheated fuel mixture, a top speed of the engine, and variable ignition timing to keep the pressure on the fuel knock resistance. Depending on the configuration of the fuel, the two modern gasoline that about 8 to 10 points lower than RON. Usually require a fuel specifications, both RON minimum and two as a minimum.

In most countries (including all of Europe and Australia) in the classification of "title" octane, as shown on the pump, is Ron, but in the United States, Canada and some other countries in the number of title is the average and two of RON, and sometimes called the index antiknock (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R + M) / 2. 8-10 point difference as referred to above, and octane display in the United States is 4 to 5 points less than the same fuel elsewhere: 87 octane fuel, and "regular" gasoline in the United States, Canada, 91-92 in Europe. But most European countries provide pumps 95 (RON) as "regular", equivalent to 90-91 U.S. (R + M) / 2, and some even 98 (RON) or 100 (RON)

It is possible to have the fuel's RON greater than 100, because iso-octane content is most striking resistance available. Can fuel and racing, and AvGas, liquefied gas and alcohol fuels such as methanol or ethanol and octane ratings of 110 or higher - RON Ethanol is a 129 (two 102, AKI 116). "Octane booster" model include the gasoline additive tetraethyl lead, MTBE and toluene. Decompose easily tetraethyl lead (the additive used in leaded gasoline) to the roots of its constituent, which reacts with the radicals of the fuel and oxygen, which begins in the combustion, thereby delaying ignition, leading to increase octane number.

♦ hydrogen does not fit well in the definitions of normal octane number. RON has a very high and low two , so that it has low resistance to knock in practice , due to the low ignition energy (mainly due to the low dissociation energy) and very high speed flame. These qualities are very desirable in rocket engines, but is undesirable in Otto cycle engines. However, mixing the secondary component (eg, in bi-fuel vehicle), and hydrogen raises the knock resistance overall. Flame speed is limited by the rest of the component species; hydrogen may reduce knock by contributing to the high thermal conductivity.

Octane Number O.N.

11:59:00 AM Oil Refinery : Description - Definitions

Fractional Distillation

The various components of crude oil have different sizes, weights and boiling temperatures; so, the first step is to separate these components. Because they have different boiling temperatures, they can be separated easily by a process called fractional distillation. The steps of fractional distillation are as follows:

1. You heat the mixture of two or more substances (liquids) with different boiling points to a high temperature. Heating is usually done with high pressure steam to temperatures of about 1112 degrees Fahrenheit / 600 degrees Celsius.
2. The mixture boils, forming vapor (gases); most substances go into the vapor phase.
3. The vapor enters the bottom of a long column (fractional distillation column) that is filled with trays or plates.

   

   Photo courtesy Phillips Petroleum
   Distillation columns in an oil refinery

   • The trays have many holes or bubble caps (like a loosened cap on a soda bottle) in them to allow the vapor to pass through.
   • The trays increase the        contact time between the vapor and the liquids in the column.
   • The trays help to collect liquids that form at various heights in the column.
   • There is a temperature difference across the column (hot at the bottom, cool at the top).
4. The vapor rises in the column.
5. As the vapor rises through the trays in the column, it cools.
6. When a substance in the vapor reaches a height where the temperature of the column is equal to that substance's boiling point, it will condense to form a liquid. (The substance with the lowest boiling point will condense at the highest point in the column; substances with higher boiling points will condense lower in the column.).
7. The trays collect the various liquid fractions.
8. The collected liquid fractions may:
   • pass to condensers, which cool them further, and then go to storage tanks
   • go to other areas for further chemical processing

Fractional distillation is useful for separating a mixture of substances with narrow differences in boiling points, and is the most important step in the refining process.

The oil refining process starts with a fractional distillation column. On the right, you can see several chemical processors that are described in the next section.

Very few of the components come out of the fractional distillation column ready for market. Many of them must be chemically processed to make other fractions. For example, only 40% of distilled crude oil is gasoline; however, gasoline is one of the major products made by oil companies. Rather than continually distilling large quantities of crude oil, oil companies chemically process some other fractions from the distillation column to make gasoline; this processing increases the yield of gasoline from each barrel of crude oil.

The oil refining process starts with a fractional distillation column.

In the next section, we'll look at how we chemically process one fraction into another.

Fractional Distillation

8:47:00 AM Oil Refinery : Description - Definitions

The Refining Process

As mentioned previously, a barrel of crude oil has a mixture of all sorts of hydrocarbons in it. Oil refining separates everything into useful substances. Chemists use the following steps:

1. The oldest and most common way to separate things into various components (called fractions), is to do it using the differences in boiling temperature. This process is called fractional distillation. You basically heat crude oil up, let it vaporize and then condense the vapor.
2. Newer techniques use Chemical processing on some of the fractions to make others, in a process called conversion. Chemical processing, for example, can break longer chains into shorter ones. This allows a refinery to turn diesel fuel into gasoline depending on the demand for gasoline.
3. Refineries must treat the fractions to remove impurities.
4. Refineries combine the various fractions (processed, unprocessed) into mixtures to make desired products. For example, different mixtures of chains can create gasolines with different octane ratings.

The products are stored on-site until they can be delivered to various markets such as gas stations, airports and chemical plants. In addition to making the oil-based products, refineries must also treat the wastes involved in the processes to minimize air and water pollution.
In the next section, we will look at how we separate crude oil into its components.

Photo courtesy Phillips Petroleum Company
An oil refinery

The Refining Process

8:23:00 AM Oil Refinery : Description - Definitions

From Crude Oil

The problem with crude oil is that it contains hundreds of different types of hydrocarbons all mixed together. You have to separate the different types of hydrocarbons to have anything useful. Fortunately there is an easy way to separate things, and this is what oil refining is all about. Different hydrocarbon chain lengths all have progressively higher boiling points, so they can all be separated by distillation. This is what happens in an oil refinery - in one part of the process, crude oil is heated and the different chains are pulled out by their vaporization temperatures. Each different chain length has a different property that makes it useful in a different way.

To understand the diversity contained in crude oil, and to understand why refining crude oil is so important in our society, look through the following list of products that come from crude oil:

• Petroleum gas - used for heating, cooking, making plastics
  • small alkanes (1 to 4 carbon atoms)
  • commonly known by the names methane, ethane, propane, butane
  • boiling range = less than 104 degrees Fahrenheit / 40 degrees Celsius
  • often liquified under pressure to create LPG (liquified petroleum gas)
• Naphtha or Ligroin - intermediate that will be further processed to make gasoline
  • mix of 5 to 9 carbon atom alkanes
  • boiling range = 140 to 212 degrees Fahrenheit / 60 to 100 degrees Celsius
• Gasoline - motor fuel
  • liquid
  • mix of alkanes and cycloalkanes (5 to 12 carbon atoms)
  • boiling range = 104 to 401 degrees Fahrenheit / 40 to 205 degrees Celsius
• Kerosene - fuel for jet engines and tractors; starting material for making other products
  • liquid
  • mix of alkanes (10 to 18 carbons) and aromatics
  • boiling range = 350 to 617 degrees Fahrenheit / 175 to 325 degrees Celsius
• Gas oil or Diesel distillate - used for diesel fuel and heating oil; starting material for making other products
  • liquid
  • alkanes containing 12 or more carbon atoms
  • boiling range = 482 to 662 degrees Fahrenheit / 250 to 350 degrees Celsius
• Lubricating oil - used for motor oil, grease, other lubricants
  • liquid
  • long chain (20 to 50 carbon atoms) alkanes, cycloalkanes, aromatics
  • boiling range = 572 to 700 degrees Fahrenheit / 300 to 370 degrees Celsius
• Heavy gas or Fuel oil - used for industrial fuel; starting material for making other products
  • liquid
  • long chain (20 to 70 carbon atoms) alkanes, cycloalkanes, aromatics
  • boiling range = 700 to 1112 degrees Fahrenheit / 370 to 600 degrees Celsius
• Residuals - coke, asphalt, tar, waxes; starting material for making other products
  • solid
  • multiple-ringed compounds with 70 or more carbon atoms
  • boiling range = greater than 1112 degrees Fahrenheit / 600 degrees Celsius

You may have noticed that all of these products have different sizes and boiling ranges. Chemists take advantage of these properties when refining oil. Look at the next section to find out the details of this fascinating process.

From Crude Oil

5:41:00 AM Oil Refinery : Description - Definitions

Crude Oil Components

On average, crude oils are made of the following elements or compounds: Carbon - 84% Hydrogen - 14% Sulfur - 1 to 3% (hydrogen sulfide, sulfides, disulfides, elemental sulfur) Nitrogen - less than 1% (basic compounds with amine groups) Oxygen - less than 1% (found in organic compounds such as carbon dioxide, phenols, ketones, carboxylic acids) Metals - less than 1% (nickel, iron, vanadium, copper, arsenic) Salts - less than 1% (sodium chloride, magnesium chloride, calcium chloride)

­Crude oil is the term for "unprocessed" oil, the stuff that comes out of the ground. It is also known as petroleum. Crude oil is a fossil fuel, meaning that it was made natural­ly from decaying plants and animals living in ancient seas millions of years ago -- most places you can find crude oil were once sea beds. Crude oils vary in color, from clear to tar-black, and in viscosity, from water to almost solid.
Crude oils are such a useful starting point for so many different substances because they contain hydrocarbons. Hydrocarbons are molecules that contain hydrogen and carbon and come in various lengths and structures, from straight chains to branching chains to rings.
There are two things that make hydrocarbons exciting to chemists:

• Hydrocarbons contain a lot of energy. Many of the things derived from crude oil like gasoline, diesel fuel, paraffin wax and so on take advantage of this energy.
• Hydrocarbons can take on many different forms. The smallest hydrocarbon is methane (CH₄), which is a gas that is a lighter than air. Longer chains with 5 or more carbons are liquids. Very long chains are solids like wax or tar. By chemically cross-linking hydrocarbon chains you can get everything from synthetic rubber to nylon to the plastic in tupperware. Hydrocarbon chains are very versatile!

The major classes of hydrocarbons in crude oils include:

• Paraffins
  • general formula: C_nH_2n+2 (n is a whole number, usually from 1 to 20)
  • straight- or branched-chain molecules
  • can be gasses or liquids at room temperature depending upon the molecule
  • examples: methane, ethane, propane, butane, isobutane, pentane, hexane
• Aromatics
  • general formula: C₆H₅ - Y (Y is a longer, straight molecule that connects to the benzene ring)
  • ringed structures with one or more rings
  • rings contain six carbon atoms, with alternating double and single bonds between the carbons
  • typically liquids
  • examples: benzene, napthalene
• Napthenes or Cycloalkanes
  • general formula: C_nH_2n (n is a whole number usually from 1 to 20)
  • ringed structures with one or more rings
  • rings contain only single bonds between the carbon atoms
  • typically liquids at room temperature
  • examples: cyclohexane, methyl cyclopentane
• Other hydrocarbons
  • Alkenes
    • general formula: C_nH_2n (n is a whole number, usually from 1 to 20)
    • linear or branched chain molecules containing one carbon-carbon double-bond
    • can be liquid or gas
    • examples: ethylene, butene, isobutene
  • Dienes and Alkynes
    • general formula: C_nH_2n-2 (n is a whole number, usually from 1 to 20)
    • linear or branched chain molecules containing two carbon-carbon double-bonds
    • can be liquid or gas
    • examples: acetylene, butadienes

­To see examples of the structures of these types of hydrocarbons, see the OSHA Technical Manual and this page on the Refining of Petroleum.
Now that we know what's in crude oil, let's see what we can make from it.

Crude Oil Components

5:36:00 AM Oil Refinery : Description - Definitions

Introduction to Oil Refinery

­I­n movies and television shows -- Giant, Oklahoma Crude, Armageddon, Beverly Hillbillies -- we have seen images of thick, black crude oil gushing out of the ground or a drilling platform.­
But when you pump the gasoline for your ­car, you've probably noticed that it is clear.
And there are so many other products that come from oil, including crayons, plastics, heating oil, jet fuel, kerosene, synthetic fibers and tires.­
­How is it possible to start with crude oil and end up with gasoline and all of these other products?­
In­ this article, we will examine the chemistry and technology involved in refining crude oil to produce all of these different things.


Photo courtesy Phillips Petroleum Company
Refineries turn crude oil into products such as gasoline, crayons and plastics. See more pictures of oil fields and refining. 

Introduction to Oil Refinery

5:31:00 AM Oil Refinery : Description - Definitions

Oil refinery

From Wikipedia

Anacortes Refinery (Tesoro), on the north end of March Point southeast of Anacortes, Washington

An oil refinery or petroleum refinery is an industrial process plant where crude oil is processed and refined into more useful petroleum products, such as gasoline, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas. Oil refineries are typically large sprawling industrial complexes with extensive piping running throughout, carrying streams of fluids between large chemical processing units. In many ways, oil refineries use much of the technology of, and can be thought of as types of chemical plants. The crude oil feedstock has typically been processed by an oil production plant. There is usually an oil depot (tank farm) at or near an oil refinery for storage of bulk liquid products.

Contents 1 Operation 2 Major products 3 Common process units found in a refinery 3.1 Flow diagram of typical refinery 4 Specialty end products 5 Siting/locating of petroleum refineries 6 Safety and environmental concerns 7 Corrosion problems and prevention 8 History 8.1 Oil refining in the United States

 Operation

Crude oil is separated into fractions by fractional distillation. The fractions at the top of the fractionating columnboiling points than the fractions at the bottom. The heavy bottom fractions are often cracked into lighter, more useful products. All of the fractions are processed further in other refining units. have lower

Raw or unprocessed crude oil is not generally useful. Although "light, sweet" (low viscosity, low sulfur) crude oil has been used 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 mowers, 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.

The oil refinery in Haifa, Israelcrude oil a year. Its two cooling towers are landmarks of the city's skyline. is capable of processing about 9 million tons (66 million barrels) of

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, and 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 broad 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 isobutane and propylene or butylenes can be recombined to meet specific octane requirements by processes such as alkylation, or less commonly, dimerization. Octane grade of gasoline can also be improved by catalytic reforming, which involves removing hydrogen from hydrocarbons producing compounds with higher octane ratings such as aromatics. Intermediate products such as gasoils can even be reprocessed to break a heavy, long-chained oil into a lighter short-chained one, by various forms of cracking such as fluid catalytic 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

Petroleum products are usually grouped into three categories: light distillates (LPG, gasoline, naphtha), middle distillates (kerosene, diesel), heavy distillates and residuum (heavy fuel oil, lubricating oils, wax, asphalt). This classification is based on the way crude oil is distilled and separated into fractions (called distillates and residuum) as in the above drawing.

• Liquified petroleum gas (LPG)
• Gasoline (also known as petrol)
• Naphtha
• Kerosene and related jet aircraft fuels
• Diesel fuel
• Fuel oils
• Lubricating oils
• Paraffin wax
• Asphalt and tar
• Petroleum coke

Common process units found in a refinery

• Desalter unit washes out salt from the crude oil before it enters the atmospheric distillation unit.
• Atmospheric distillation unit distills crude oil into fractions. See Continuous distillation.
• Vacuum distillation unit further distills residual bottoms after atmospheric distillation.
• Naphtha hydrotreater unit uses hydrogen to desulfurize naphtha from atmospheric distillation. Must hydrotreat 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 byproduct of a reformer is hydrogen released during the catalyst reaction. The hydrogen is used either in the hydrotreaters or the hydrocracker.
• Distillate hydrotreater unit desulfurizes 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.
• Coking units (delayed coking, fluid coker, and flexicoker) process very heavy residual oils into gasoline and diesel fuel, leaving petroleum coke as a residual product.
• Alkylation unit produces high-octane component for gasoline blending.
• Dimerization unit converts olefins into higher-octane gasoline blending components. For example, butenes can be dimerized into isooctene which may subsequently be hydrogenated to form isooctane. There are also other 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 or hydrocracker.
• Liquified gas storage units store propane and similar gaseous fuels at pressure sufficient to maintain them in liquid form. These are usually spherical vessels or bullets (horizontal vessels with rounded ends.
• Storage tanks store crude oil and finished products, usually cylindrical, with some sort of vapor emission control and surrounded by an earthen berm to contain spills.
• Slug catcher used when product (crude oil and gas) that comes from a pipeline with two-phase flow, has to be buffered at the entry of the units.
• Amine gas treater, Claus unit, and tail gas treatment convert hydrogen sulfide from hydrodesulfurization into elemental sulfur.
• Utility units such as cooling towers circulate cooling water, boiler plants generates steam, and instrument air systems include pneumatically operated control valves and an electrical substation.
• Wastewater collection and treating systems consist of API separators, dissolved air flotation (DAF) units and further treatment units such as an activated sludge biotreater to make 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.

Flow diagram of typical refinery

The image below is a schematic flow diagram of a typical oil refinery that depicts the various unit processes and the flow of intermediate product streams that occurs between the inlet crude oil feedstock and the final end products. The diagram depicts only one of the literally hundreds of different oil refinery configurations. The diagram also does not include any of the usual refinery facilities providing utilities such as steam, cooling water, and electric power as well as storage tanks for crude oil feedstock and for intermediate products and end products.

Schematic flow diagram of a typical oil refinery

There are many process configurations other than that depicted above. For example, the vacuum distillation unit may also produce fractions that can be refined into endproducts such as: spindle oil used in the textile industry, light machinery oil, motor oil, and steam cylinder oil. As another example, the vacuum residue may be processed in a coker unit to produce petroleum coke.

Specialty end products

Sarnia, Ontario is a major Great LakesShell, Imperial Oil, ExxonMobil, Suncor Energy, Dow Chemicals, Bayer, and others. refining area for these will blend various feedstocks, mix appropriate additives, provide short term storage, and prepare for bulk loading to trucks, barges, product ships, and railcars.

• Gaseous fuels such as propane, stored and shipped in liquid form under pressure in specialized railcars to distributors.
• Liquid fuels blending (producing automotive and aviation grades of gasoline, kerosene, various aviation turbine fuels, and diesel fuels, adding dyes, detergents, antiknock additives, oxygenates, and anti-fungal compounds as required). Shipped by barge, rail, and tanker ship. May be shipped regionally in dedicated pipelines to point consumers, particularly aviation jet fuel to major airports, or piped to distributors in multi-product pipelines using product separators called pipeline inspection gauges ("pigs").
• Lubricants (produces light machine oils, motor oils, and greases, adding viscosity stabilizers as required), usually shipped in bulk to an offsite packaging plant.
• Wax (paraffin), used in the packaging of frozen foods, among others. May be shipped in bulk to a site to prepare as packaged blocks.
• Sulfur (or sulfuric acid), byproducts of sulfur removal from petroleum which may have up to a couple percent sulfur as organic sulfur-containing compounds. Sulfur and sulfuric acid are useful industrial materials. Sulfuric acid is usually prepared and shipped as the acid precursor oleum.
• Bulk tar shipping for offsite unit packaging for use in tar-and-gravel roofing.
• Asphalt unit. Prepares bulk asphalt for shipment.
• Petroleum coke, used in specialty carbon products or as solid fuel.
• Petrochemicals or petrochemical feedstocks, which are often sent to petrochemical plants for further processing in a variety of ways. The petrochemicals may be olefins or their precursors, or various types of aromatic petrochemicals.

Siting/locating of petroleum refineries

A party searching for a site to construct a refinery or a chemical plant needs to consider the following issues:

• The site has to be reasonably far from residential areas.

• Infrastructure should be available for supply of raw materials and shipment of products to markets.

• Energy to operate the plant should be available.

• Facilities should be available for waste disposal.

Refineries which use a large amount of steam and cooling water need to have an abundant source of water. Oil refineries therefore are often located nearby navigable rivers or on a sea shore, nearby a port. Such location also gives access to transportation by river or by sea. The advantages of transporting crude oil by pipeline are evident, and oil companies often transport a large volume of fuel to distribution terminals by pipeline. Pipeline may not be practical for products with small output, and rail cars, road tankers, and barges are used.

Petrochemical plants and solvent manufacturing (fine fractionating) plants need spaces for further processing of a large volume of refinery products for further processing, or to mix chemical additives with a product at source rather than at blending terminals.

 Safety and environmental concerns

Fire at Union Oil refinery, Wilmington, California, 1951

MiRO refinery at Karlsruhe

The refining process releases numerous different chemicals into the atmosphere; consequently, there are substantial air pollution emissions and a notable odor normally accompanies the presence of a refinery. Aside from air pollution impacts there are also wastewater concerns, risks of industrial accidents such as fire and explosion, and noise health effects due to industrial noise.

The public has demanded that many governments place restrictions on contaminants that refineries release, and most refineries have installed the equipment needed to comply with the requirements of the pertinent environmental protection regulatory agencies. In the United States, there is strong pressure to prevent the development of new refineries, and no major refinery has been built in the country since Marathon's Garyville, Louisiana facility in 1976. However, many existing refineries have been expanded during that time. Environmental restrictions and pressure to prevent construction of new refineries may have also contributed to rising fuel prices in the United States. Additionally, many refineries (over 100 since the 1980s) have closed due to obsolescence and/or merger activity within the industry itself. This activity has been reported to Congress and in specialized studies not widely publicised.

Environmental and safety concerns mean that oil refineries are sometimes located some distance away from major urban areas. Nevertheless, there are many instances where refinery operations are close to populated areas and pose health risks such as in the Campo de Gibraltar, a CEPSA refinery near the towns of Gibraltar, Algeciras, La Linea, San RoqueLos Barrios with a combined population of over 300,000 residents within a 5-mile (8.0 km) radius and the CEPSA refinery in Santa Cruz on the island of Tenerife, Spain which is sited in a densely populated city center and next to the only two major evacuation routes in and out of the city. In California's Contra Costa County and Solano County, a shoreline necklace of refineries, built in the early 1900s before this area was populated, and associated chemical plants are adjacent to urban areas in Richmond, Martinez, Pacheco, Concord, Pittsburg, Vallejo and Benicia, with occasional accidental events that require "shelter in place" orders to the adjacent populations.

Corrosion problems and prevention

Corrosion occurs in various forms in the refining process, such as pitting corrosion from water droplets, embrittlement from hydrogen, and stress corrosion cracking from sulfide attack. From a materials standpoint, carbon steel is used for upwards of 80% of refinery components, which is beneficial due to its low cost. Carbon steel is resistant to the most common forms of corrosion, particularly from hydrocarbon impurities at temperatures below 205 °C, but other corrosive chemicals and environments prevent its use everywhere. Common replacement materials are low alloy steels containing chromium and molybdenum, with stainless steels containing more chromium dealing with more corrosive environments. More expensive materials commonly used are nickel, titanium, and copper alloys. These are primarily saved for the most problematic areas where extremely high temperatures or very corrosive chemicals are present. Petroleum refineries run as efficiently as possible to reduce costs. One major factor that decreases efficiency is corrosion of the metal components found throughout the process line of the hydrocarbon refining process. Corrosion causes the failure of parts in addition to dictating the cleaning schedule of the refinery, during which the entire production facility must be shut down and cleaned. The cost of corrosion in the petroleum industry has been estimated at US$3.7 billion.

Corrosion is fought by a complex system of monitoring, preventative repairs and careful use of materials. Monitoring methods include both off-line checks taken during maintenance and on-line monitoring. Off-line checks measure corrosion after it has occurred, telling the engineer when equipment must be replaced based on the historical information he has collected. This is referred to as preventative management.

On-line systems are a more modern development, and are revolutionizing the way corrosion is approached. There are several types of on-line corrosion monitoring technologies such as linear polarization resistance, electrochemical noise and electrical resistance. On-Line monitoring has generally had slow reporting rates in the past (minutes or hours) and been limited by process conditions and sources of error but newer technologies can report rates up to twice per minute with much higher accuracy (referred to as real-time monitoring). This allows process engineers to treat corrosion as another process variable that can be optimized in the system. Immediate responses to process changes allow the control of corrosion mechanisms, so they can be minimized while also maximizing production output. In an ideal situation having on-line corrosion information that is accurate and real-time will allow conditions that cause high corrosion rates to be identified and reduced. This is known as predictive management.

Materials methods include selecting the proper material for the application. In areas of minimal corrosion, cheap materials are preferable, but when bad corrosion can occur, more expensive but longer lasting materials should be used. Other materials methods come in the form of protective barriers between corrosive substances and the equipment metals. These can be either a lining of refractory material such as standard Portland cement or other special acid-resistant cements that are shot onto the inner surface of the vessel. Also available are thin overlays of more expensive metals that protect cheaper metal against corrosion without requiring lots of material.

History

The first oil refineries in the world were built by Ignacy Łukasiewicz near Jasło, Austrian Empire (now in Poland) from 1854 to 1856, but they were initially small as there was no real demand for refined fuel. As Łukasiewicz's kerosene lamp gained popularity, the refining industry grew in the area.

World's first large refinery opened at Ploesti (today known as Ploieşti), Romania, in 1856-1857, with US investment. After being taken over by Nazi Germany, the Ploesti refineries were bombed in Operation Tidal Wave by the Allies during the Oil Campaign of World War II. Another early large refinery is Oljeön, Sweden (1875), now preserved as a museum at the UNESCO world heritage site Engelsberg and part of the Ecomuseum Bergslagen.

At one point, the refinery in Ras Tanura, Saudi Arabia owned by Saudi Aramco was claimed to be the largest oil refinery in the world. For most of the 20th century, the largest refinery was the Abadan Refinery in Iran. This refinery suffered extensive damage during the Iran-Iraq war. The world's largest refinery complex is the Jamnagar Refinery Complex, consisting of two refineries side by side operated by Reliance Industries Limited in Jamnagar, India with a combined production capacity of 1,240,000 barrels per day (197,000 m³/d) (J-1 660,000 bbl/d (105,000 m³/d), J-2 580,000 bbl/d (92,000 m³/d). PDVSA's Paraguana refinery complex in Venezuela with a capacity of 956,000 bbl/d (152,000 m³/d) and SK Energy's Ulsan in South Korea with 840,000 bbl/d (134,000 m³/d) are the second and third largest, respectively

Oil refining in the United States

In the 1800s, refineries in the U.S. processed crude oil primarily to recover the kerosene. There was no market for the more volatile fraction, including gasoline, which was considered waste and was often dumped directly into the nearest river. The invention of the automobile shifted the demand to gasoline and diesel, which remain the primary refined products today. Today, national and state legislation requires refineries to meet stringent air and water cleanliness standards. In fact, oil companies in the U.S. perceive obtaining a permit to build a modern refinery to be so difficult and costly that no new refineries have been built (though many have been expanded) in the U.S. since 1976. More than half the refineries that existed in 1981 are now closed due to low utilization rates and accelerating mergers. As a result of these closures total US refinery capacity fell between 1981 to 1995, though the operating capacity stayed fairly constant in that time period at around 15,000,000 barrels per day (2.4E+6 m³/d). In 2009 through 2010, as revenue streams in the oil business dried up and profitability of oil refineries fell due to lower demand for product and high reserves of supply preceding the economic recession, oil companies began to close or sell refineries. Due to EPA regulations, the costs associated with closing a refinery are very high, meaning that many former refineries are repurposed.

Oil refinery

12:46:00 PM Oil Refinery : Description - Definitions