An
oil refinery is an industrial
processAn oil production plant is a facility which performs processing of production fluids from oil wells in order to separate out key components and prepare them for export. This is distinct from an oil depot, which do not have processing facilities.Typical production fluids are a mixture of oil, ...
plant where crude oil is processed and refined into more useful petroleum products, such as
gasolineGasoline or petrol is a petroleum-derived liquid mixture, primarily used as fuel in internal combustion engines...
, diesel fuel,
asphalt baseAsphalt is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits sometimes termed asphaltum...
,
heating oilHeating oil, or oil heat, is a low viscosity, flammable liquid petroleum product used as a fuel for [furnace]]s or boilers in buildings....
,
keroseneKerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
and liquefied petroleum gas. Oil refineries are typically large sprawling
industrialAn industry is the manufacturing of a good or service within a category. Although industry is a broad term for any kind of economic production, in economics and urban planning industry is a synonym for the secondary sector, which is a type of economic activity involved in the manufacturing of raw...
complexes with extensive
pipingWithin industry, piping is a system of pipes used to convey fluids from one location to another. The engineering discipline of piping design studies the efficient transport of fluid....
running throughout, carrying streams of
fluidA fluid is a substance that continually deforms under an applied shear stress. All gases are fluids, but not all liquids are fluids. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
s between large
chemical processIn a "scientific" sense, a chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. Such a chemical process can occur by itself or be caused by somebody. Such a chemical process commonly involves a chemical reaction of some sort...
ing units.
Operation
Raw or unprocessed crude oil is not generally useful. Although "light, sweet" (low viscosity, low
sulfurSulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant, multivalent non-metal. Sulfur, in its native form, is a yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals...
) 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
petrochemicalPetrochemicals are chemical products made from raw materials of petroleum or other hydrocarbon origin. Although some of the chemical compounds that originate from petroleum may also be derived from coal and natural gas, petroleum is the major source...
processes that manufacture such products as
plasticPlastic is the general common term for a wide range of synthetic or semisynthetic organic amorphous solid materials suitable for the manufacture of industrial products...
s,
detergentA detergent is a material intended to assist cleaning. The term is sometimes used to differentiate between soap and other surfactants used for cleaning...
s,
solventA solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution.The most common solvent in everyday life is water. Most other commonly-used solvents are organic chemicals. These are called organic solvents...
s,
elastomerAn elastomer is a polymer with the property of elasticity. The term, which is derived from elastic polymer, is often used interchangeably with the term rubber, although the latter is preferred when referring to vulcanisates. Each of the monomers which link to form the polymer is usually made of...
s and
fiberFiber, also spelled fibre, is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread. They are very important in the biology of both plants and animals, for holding tissues together. Human uses for fibers are diverse...
s such as
nylonNylon is a generic designation for a family of synthetic polymers known generically as polyamides and first produced on February 28, 1935 by Wallace Carothers at DuPont...
and polyesters.
PetroleumPetroleum or crude oil is a naturally occurring, flammable liquid found in rock formations in the Earth consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds.The term "petroleum" was first used in the treatise De Natura Fossilium, published in...
fossil fuels are burned in internal combustion engines to provide power for ships, automobiles, aircraft
engineAn engine is a machine that produces mechanical force and motion from another form of energy . It is also referred to as a prime mover. An automobile makes use of several motors to start the car and drive the car's various pumps – but the power plant that propels the car is called an engine...
s, lawn mowers, chainsaws, and other machines. Different
boiling pointThe boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid....
s allow the
hydrocarbonIn organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. With relation to chemical terminology, aromatic hydrocarbons or arenes, alkanes, alkenes and alkyne-based compounds composed entirely of carbon and hydrogen are referred to as "pure"...
s to be separated by
distillationDistillation is a method of separating mixtures based on differences in their volatilities in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
. 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 massThe molecular mass of a substance, frequently referred to by the older term molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u...
es, forms and lengths such as
paraffinIn chemistry, paraffin is the common name for the alkane hydrocarbons with the general formula CnH2n+2. Paraffin wax refers to the solids with 20 ≤ n ≤ 40 ....
s, aromatics, naphthenes (or
cycloalkaneCycloalkanes are types of alkanes which have one or more rings of carbon atoms in the chemical structure of their molecules. Alkanes are types of organic hydrocarbon compounds which have only single chemical bonds in their chemical structure...
s),
alkeneIn organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
s,
dieneDienes or diolefins are hydrocarbons which contain two double bonds. Dienes are intermediate between alkenes and polyenes.-Classes:Dienes can be divided into three classes:...
s, and
alkyneAlkynes are hydrocarbons that have a triple bond between two carbon atoms, with the formula CnH2n-2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC...
s. 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
hydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
and
carbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
atomThe atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s, 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
isobutaneIsobutane, also known as methylpropane or 2-methylpropane, is an alkane, isomeric with butane. Recent concerns with depletion of the ozone layer by freon gases have led to increased use of isobutane as a gas for refrigeration systems, especially in domestic refrigerators and freezers, and as a...
and
propylenePropene, also known as propylene, is an unsaturated organic compound having the chemical formula C3H6. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons, and it is also second in natural abundance.-Properties:At room temperature,...
or butylenes can be recombined to meet specific
octaneThe octane rating is a measure of the resistance of gasoline and other fuels to detonation in spark-ignition internal combustion engines. High-performance engines typically have higher compression ratios and are therefore more prone to detonation, so they require higher octane fuel...
requirements by processes such as
alkylationAlkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene . Alkylating agents are widely used in chemistry because the alkyl group is probably the most common group encountered in...
, or less commonly, dimerization. Octane grade of gasoline can also be improved by
catalytic reformingCatalytic reforming is a chemical process used to convert petroleum refinery naphthas, typically having low octane ratings, into high-octane liquid products called reformates which are components of high-octane gasoline...
, 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
crackingIn petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules by the breaking of carbon-carbon bonds in the precursors. The rate of cracking and the end products are strongly dependent on...
such as
fluid catalytic crackingFluid catalytic cracking is the most important conversion process used in petroleum refineries. It is widely used to convert the high-boiling, high-molecular weight hydrocarbon fractions of petroleum crude oils to more valuable gasoline, olefinic gases and other products...
, thermal cracking, and hydrocracking. The final step in gasoline production is the blending of fuels with different octane ratings,
vapor pressureVapor pressure or equilibrium vapor pressure is the pressure of a vapor in thermodynamic equilibrium with its condensed phases in a closed container. All liquids and solids have a tendency to evaporate into a gaseous form, and all gases have a tendency to condense back to their liquid or solid...
s, 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
continuouslyContinuous production is a method used to manufacture, produce, or process materials without interruption.This process is followed in most oil and gas industries and petrochemical plant and in other industries such as the float glass industry, where glass of different thickness is processed in a...
, as opposed to processing in
batchesBatch production is the manufacturing technique of creating a component at a workstation before moving to the next step in production. Batch production is common in bakeries and in the manufacture of sports shoes, pharmaceutical ingredients , inks, paints and adhesives. In the manufacture of inks...
, at
steady stateA system in a steady state has numerous properties that are unchanging in time. The concept of steady state has relevance in many fields, in particular thermodynamics. Steady state is a more general situation than dynamic equilibrium. If a system is in steady state, then the recently observed...
or nearly steady state for months to years. The high capacity also makes
process optimizationProcess optimization is the discipline of adjusting a process so as to optimize some specified set of parameters without violating some constraint. The most common goals are minimizing cost, maximizing throughput, and/or efficiency...
and
advanced process controlIn control theory Advanced process control is a broad term composed of different kinds of process control tools, often used for solving multivariable control problems or discrete control problem.- Overview :...
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, tar). This classification is based on the way crude oil is distilled and separated into fractions (called distillates and residuum) as in the above drawing.
- Liquid petroleum gas (LPG)
- Gasoline
Gasoline or petrol is a petroleum-derived liquid mixture, primarily used as fuel in internal combustion engines...
(also known as petrol)
- Naphtha
Naphtha normally refers to a number of different flammable liquid mixtures of hydrocarbons, i.e. a distillation product from petroleum or coal tar boiling in a certain range and containing certain hydrocarbons, a broad term encompassing any volatile, flammable liquid hydrocarbon mixture.Naphtha is...
- Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
and related jet aircraft fuelsJet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw colored. The most common fuels are Jet A and Jet A-1 which are produced to an internationally standardized set of specifications...
- Diesel fuel
- Fuel oil
Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash...
s
- Lubricating oil
A lubricant is a substance introduced between two moving surfaces to reduce the friction between them, improving efficiency and reducing wear often used while having sex...
s
- Paraffin wax
- Asphalt
Asphalt is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits sometimes termed asphaltum...
and TarTar is modified resin produced primarily from the wood and roots of pine by destructive distillation under pyrolysis. It is a viscous black liquid. Production and trade in tar was a major contributor in the economies of Northern Europe and Colonial America. Its main use was in preserving and...
- Petroleum coke
Petroleum coke is a carbonaceous solid derived from oil refinery coker units or other cracking processes. Other coke has traditionally been derived from coal....
Common process units found in a refinery
- Desalter
A desalter is a process unit on an oil refinery that removes salt from the crude oil. The salt is dissolved in the water in the crude oil, not in the crude oil itself. The desalting is usually the first process in crude oil refining. The salt content after the desalter is usually measured in PTB -...
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
Continuous distillation, a form of distillation, is an ongoing separation in which a mixture is continuously fed into the process and separated fractions are removed continuously as output streams as time passes during the operation...
.
- Vacuum Distillation
Vacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure causing evaporation of the most volatile liquid...
unit further distills residual bottoms after atmospheric distillation.
- Naphtha Hydrotreater unit uses hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
to desulfurize naphtha from atmospheric distillation. Must hydrotreat the naphtha before sending to a Catalytic Reformer unit.
- Catalytic Reformer
Catalytic reforming is a chemical process used to convert petroleum refinery naphthas, typically having low octane ratings, into high-octane liquid products called reformates which are components of high-octane gasoline...
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
Fluid catalytic cracking is the most important conversion process used in petroleum refineries. It is widely used to convert the high-boiling, high-molecular weight hydrocarbon fractions of petroleum crude oils to more valuable gasoline, olefinic gases and other products...
(FCC) unit upgrades heavier fractions into lighter, more valuable products.
- Hydrocracker
In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules by the breaking of carbon-carbon bonds in the precursors. The rate of cracking and the end products are strongly dependent on...
unit uses hydrogen to upgrade heavier fractions into lighter, more valuable products.
- Visbreaking
A visbreaker is a processing unit in oil refinery whose purpose is to reduce the quantity of residual oil produced in the distillation of crude oil and to increase the yield of more valuable middle distillates by the refinery...
unit upgrades heavy residual oils by thermally cracking them into lighter, more valuable reduced viscosity products.
- Merox
Merox is an acronym for mercaptan oxidation. It is a proprietary catalytic chemical process developed by UOP used in oil refineries and natural gas processing plants to remove mercaptans from LPG, propane, butanes, light naphthas, kerosene and jet fuel by converting them to liquid hydrocarbon...
unit treats LPG, kerosene or jet fuel by oxidizing mercaptans to organic disulfideIn chemistry, a disulfide usually refers to the structural unit composed of a linked pair of sulfur atoms. Disulfide usually refer to a chemical compound that contains a disulfide bond, such as diphenyl disulfide, C
6H
5S-SC
6H
5.-Inorganic vs. organic...
s.
- Coking unit
A coker or coker unit is an oil refinery processing unit that converts the residual oil from the vacuum distillation column or the atmospheric distillation column into low molecular weight hydrocarbon gases, naphtha, light and heavy gas oils, and petroleum coke...
s (delayed coking, fluid coker, and flexicoker) process very heavy residual oils into gasoline and diesel fuel, leaving petroleum coke as a residual product.
- Alkylation
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene . Alkylating agents are widely used in chemistry because the alkyl group is probably the most common group encountered in...
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
Fossil fuel reforming, hydrogen reforming or catalytic oxidation, is a method of producing useful products, such as hydrogen or ethylene from fossil fuels. Fossil fuel reforming is done through a fossil fuel processor or reformer. At present, the most common fossil fuel processor is a steam...
unit produces hydrogen for the hydrotreaters or hydrocracker.
- Liquified 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 tanks for crude oil and finished products, usually cylindrical, with some sort of vapor emission control and surrounded by an earthen berm
A berm is a level space, shelf, or raised barrier separating two areas. Berm is a loanword from Dutch.-History:In medieval military engineering, a berm was a level space between a parapet or defensive wall and an adjacent steep-walled ditch or moat. It was intended to reduce soil pressure on the...
to contain spills.
- Amine gas treater, Claus unit
The Claus process is the most significant gas desulfurizing process, recovering elemental sulfur from gaseous hydrogen sulfide. First patented in 1883 by the scientist Carl Friedrich Claus, the Claus process has become the industry standard....
, and tail gas treatment for converting hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
from hydrodesulfurizationHydrodesulfurization is a catalytic chemical process widely used to remove sulfur from natural gas and from refined petroleum products such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils...
into elemental sulfur.
- Utility units such as cooling towers for circulating cooling water, boiler plants
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Overview:-Materials:...
for steamSteam is vaporized water. It is a transparent gas . At standard temperature and pressure, pure steam occupies about 1,600 times the volume of an equal mass of liquid water...
generation, instrument air systems for pneumatically operated control valvesControl valves are valves used to control conditions such as flow, pressure, temperature, and liquid level by fully or partially opening or closing in response to signals received from controllers that compare a "setpoint" to a "process variable" whose value is provided by sensors that monitor...
and an electrical substationAn electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers...
.
- Wastewater
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...
collection and treating systems consisting of API separators, dissolved air flotation (DAF) units and some type of further treatment (such as an activated sludgeActivated sludge is a process dealing with the treatment of sewage and industrial wastewaters and developed around 1912-1914,]. Atmospheric air or pure oxygen is bubbled through primary treated sewage combined with organisms to develop a biological floc which reduces the organic content of the...
biotreater) to make such water suitable for reuse or for disposal.
- Solvent refining units use solvent such as cresol
Cresols are organic compounds which are methylphenols. They are a widely occurring natural and manufactured group of aromatic organic compounds which are categorized as phenols . Depending on the temperature, cresols can be solid or liquid because they have melting points not far from room...
or furfuralFurfural is an industrial chemical compound derived from a variety of agricultural byproducts, including corncobs, oat and wheat bran, and sawdust. The name furfural comes from the Latin word , meaning bran, referring to its usual source....
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 diagramA process flow diagram is a diagram commonly used in chemical and process engineering to indicate the general flow of plant processes and equipment. The PFD displays the relationship between major equipment of a plant facility and does not show minor details such as piping details and designations...
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.
There are many process configurations other than that depicted above. For example, the
vacuum distillationVacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure causing evaporation of the most volatile liquid...
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 unitA coker or coker unit is an oil refinery processing unit that converts the residual oil from the vacuum distillation column or the atmospheric distillation column into low molecular weight hydrocarbon gases, naphtha, light and heavy gas oils, and petroleum coke...
to produce petroleum coke.
Specialty end products
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
Propane is a three-carbon alkane, normally a gas, but compressible to a transportable liquid. It is derived from other petroleum products during oil or natural gas processing...
, 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 pipeline
Pipeline transport is the transportation of goods through a pipe. Most commonly, liquid and gases are sent, but pneumatic tubes that transport solid capsules using compressed air have also been used....
s 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").
- Lubricant
A lubricant is a substance introduced between two moving surfaces to reduce the friction between them, improving efficiency and reducing wear often used while having sex...
s (produces light machine oils, motor oilMotor oil, or engine oil, is an oil used for lubrication of various internal combustion engines. While the main function is to lubricate moving parts, motor oil also cleans, inhibits corrosion, improves sealing and cools the engine by carrying heat away from moving parts...
s, and greaseThe term grease is used to describe a number of semisolid lubricants possessing a higher initial viscosity than oil. Although the word grease is also used to describe rendered fat of animals, in the context of lubricants, it typically applies to a material consisting of a calcium, sodium or...
s, adding viscosityViscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness." Thus, water is "thin," having a lower viscosity, while honey is "thick," having a higher viscosity...
stabilizers as required), usually shipped in bulk to an offsite packaging plant.
- Wax
Wax refers to beeswax or another substance with similar properties. The traditional meaning, beeswax, refers to a substance secreted by bees and used by them in constructing their honeycombs...
(paraffin), used in the packaging of frozen foodFrozen food is food preserved by the process of freezing. Freezing food is a common method of food preservation which slows both food decay and, by turning water to ice, makes it unavailable for most bacterial growth and slows down most chemical reactions....
s, among others. May be shipped in bulk to a site to prepare as packaged blocks.
- Sulfur
Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant, multivalent non-metal. Sulfur, in its native form, is a yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals...
(or sulfuric acidSulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
), 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 oleumOleum , or fuming sulfuric acid refers to a solution of various compositions of sulfur trioxide in sulfuric acid or sometimes more specifically to disulfuric acid ....
.
- Bulk tar
Tar is modified resin produced primarily from the wood and roots of pine by destructive distillation under pyrolysis. It is a viscous black liquid. Production and trade in tar was a major contributor in the economies of Northern Europe and Colonial America. Its main use was in preserving and...
shipping for offsite unit packaging for use in tar-and-gravel roofing.
- Asphalt
Asphalt is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits sometimes termed asphaltum...
unit. Prepares bulk asphalt for shipment.
- Petroleum coke
Petroleum coke is a carbonaceous solid derived from oil refinery coker units or other cracking processes. Other coke has traditionally been derived from coal....
, used in specialty carbon products or as solid fuel.
- Petrochemical
Petrochemicals are chemical products made from raw materials of petroleum or other hydrocarbon origin. Although some of the chemical compounds that originate from petroleum may also be derived from coal and natural gas, petroleum is the major source...
s or petrochemical feedstocks, which are often sent to petrochemical plantA chemical plant is an industrial process plant that manufactures chemicals, usually on a large scale. The general objective of a chemical plant is to create new material wealth via the chemical or biological transformation and or separation of materials. Chemical plants use special equipment,...
s 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
The principles of finding a construction site for refineries are similar to those for other chemical plants:
- The site has to be reasonably far from residential areas.
- Facilities for raw materials access and products delivery to markets should be easily available.
- Processing energy requirements should be easily available.
- Waste product disposal should not cause difficulties.
For refineries which use large amounts of process steam and cooling water, an abundant source of water is important. Because of this, oil refineries are often located (associated to a port) near navigable rivers or even better on a sea shore. Either are of dual purpose, making also available cheap transport by river or by sea. Although the advantages of crude oil transport by pipeline are evident, and the method is also often used by oil companies to deliver large output products such as fuels to their bulk distribution terminals, pipeline delivery is not practical for small output products. For these, rail cars, road tankers or barges may be used.
It is useful to site refineries in areas where there is abundant space to be used by the same company or others, for the construction of petrochemical plants, solvent manufacturing (fine fractionating) plants and/or similar plants to allow these easy access to large output refinery products for further processing, or plants that produce chemical additives that the refinery may need to blend into a product at source rather than at blending terminals.
Safety and environmental concerns
The refining process releases numerous different chemicals into the
atmosphereThe Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
; consequently, there are substantial
air pollutionAir pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment, into the atmosphere....
emissions and a notable
odorAn odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also called smells, which can refer to both pleasant and unpleasant odors...
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 effectsNoise health effects are the health consequences of elevated sound levels. Elevated workplace or other noise can cause hearing impairment, hypertension, ischemic heart disease, annoyance, sleep disturbance, and decreased school performance. Changes in the immune system and birth defects have been...
due to
industrial noiseIndustrial noise is usually considered mainly from the point of view of environmental health and safety, rather than nuisance, as sustained exposure can cause permanent hearing damage. Traditionally, workplace noise has been a hazard linked to heavy industries such as ship-building and associated...
.
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'sMarathon Petroleum Company is a fully owned, American subsidiary of the Marathon Oil Corporation. The subsidiary was formed on September 1, 2005, from the former Marathon Ashland Petroleum, LLC, and is based in Findlay, Ohio...
Garyville, LouisianaGaryville is a census-designated place in St. John the Baptist Parish, Louisiana, United States. The population was 2,775 at the 2000 census. It is part of the New Orleans–Metairie–Kenner Metropolitan Statistical Area...
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 GibraltarThe comarca of the Campo de Gibraltar is one of six traditional and tourist subdivisions of the province of Cádiz, Spain, in the southwestern part of the autonomous community of Andalusia, the southernmost part of continental Western Europe.A Spanish comarca is...
, a CEPSA refinery near the towns of
GibraltarGibraltar is a self-governing British overseas territory located on the southern end of the Iberian Peninsula and Europe at the entrance of the Mediterranean overlooking the Strait of Gibraltar. The territory covers and shares a land border with Spain to the north...
,
AlgecirasAlgeciras is a port city in the south of Spain, and is the largest urban area on the Bay of Gibraltar . It is the busiest port in Spain. It is situated on the Río de la Miel 20 km north of Tarifa, which is the southernmost town of the Iberian peninsula and continental Europe. It has a population in...
,
La LineaSpain , officially the Kingdom of Spain , is a country located in southwestern Europe on the Iberian Peninsula.
[The Spanish constitution does not establish any official denomination of the country, even though España , Estado español and Nación española are used interchangeably...]
, San Roque and
Los BarriosLos Barrios is a small town and municipality in the south of Spain. It is part of the province of Cádiz, which in turn is part of the Andalusia region. It belongs to the Campo de Gibraltar comarca. The municipality has a total surface of 332 km² and a population of 20,119 as of 2006...
with a combined population of over 300,000 residents within a radius and the CEPSA refinery in Santa Cruz on the island of
TenerifeTenerife, a Spanish island, is the largest of the seven Canary Islands in the Atlantic Ocean off the coast of Africa. Tenerife has an area of 2034.38 square kilometers, and 886,033 inhabitants, which make it the most populated island of the Canary Islands and Spain. About five million tourists...
, 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
CaliforniaCalifornia is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil...
's Contra Costa County and Solano County, a shoreline necklace of refineries and associated chemical plants are adjacent to urban areas in
RichmondThe Chevron Richmond refinery is a 2,900 acre petroleum refinery in Richmond, California, on San Francisco Bay. It is owned and operated by Chevron Corporation and employs more than 1,200 workers, making it the city's largest employer. The refinery processes approximately 240,000 barrels of crude...
,
MartinezMartinez is a city in and the county seat of Contra Costa County, California, United States. The population was 35,866 at the 2000 census. The downtown is notable for its large number of preserved old buildings...
,
PachecoPacheco is a census-designated place in Contra Costa County, California, United States. The population was 3,562 at the 2000 census. It is located north of Walnut Creek.-Geography:...
,
ConcordConcord is the largest city in Contra Costa County, California, USA, and the 202nd largest in the U.S. As of the 2000 census, the city had a total population of 121,780. Originally founded in 1869 as the community of Todos Santos by Salvio Pacheco, the name was changed to Concord within months...
,
PittsburgPittsburg is a city located in eastern Contra Costa County, California, the outer portion of the East Bay region of the San Francisco Bay Area.It has one BART station, the Pittsburg/Bay Point Station located in Bay Point.The current zip code is 94565 for both...
,
VallejoVallejo is the largest city in Solano County, California, United States. The population was 116,760 at the 2000 census. It is located in the San Francisco Bay Area on the northeastern shore of San Pablo Bay...
and
BeniciaBenicia is a waterside city in Solano County, California, United States. It was the first city in California to be founded by Anglo-Americans, and served as the state capital for nearly thirteen months from 1853 to 1854. The population was 26,865 at the 2000 census. The city is located in the San...
, with occasional accidental events that require "shelter in place" orders to the adjacent populations.
Corrosion problems and prevention
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.
CorrosionCorrosion is the disintegration of a material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means a loss of electrons of metals reacting with water and oxygen. Weakening of iron due to oxidation of the iron atoms is a...
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 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
oC, but other corrosive chemicals and environments prevent its use everywhere. Common replacement materials are
low alloy steelAlloy steel is steel alloyed with other elements in amounts of between 1 and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. The differentiation between the two is somewhat arbitrary; Smith and Hashemi define...
s containing
chromiumChromium is a chemical element which has the symbol Cr and atomic number 24, first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odourless, tasteless, and malleable...
and
molybdenumMolybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The free element, which is a silvery metal, has the sixth-highest melting point of any element. It readily forms hard, stable carbides, and for this reason it is often used in high-strength steel alloys...
, with stainless steels containing more chromium dealing with more corrosive environments. More expensive materials commonly used are
nickelNickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. It is one of the four ferromagnetic elements at about room temperature, other three being iron, cobalt and gadolinium...
,
titaniumTitanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the “space age metal”, it has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color.Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among other...
, and
copperCopper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable and a freshly-exposed surface has a pinkish or peachy color...
alloys. These are primarily saved for the most problematic areas where extremely high temperatures or very corrosive chemicals are present.
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"Electrochemical noise" is the generic term given to fluctuations of current and potential. When associated with corrosion is the result of stochastic pulses of current generated by sudden film rupture, crack propagation, discrete events involving metal dissolution and hydrogen discharge with gas...
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 EmpireThe Austrian Empire was a modern era successor empire founded on a remnant of the Holy Roman Empire centered on what is today's Austria that officially lasted from 1804 to 1867...
(now in
PolandPoland , officially the Republic of Poland , is a country in Central Europe . Poland is bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
) from 1854 to 1856, but they were initially small as there was no real demand for refined fuel. As Łukasiewicz's
kerosene lampThe kerosene lamp is any type of lighting device which uses kerosene as a fuel...
gained popularity, the refining industry grew in the area.
World's first large refinery opened at Ploesti (today known as
PloieştiPloieşti is the county seat of Prahova County and lies in the historical region of Wallachia, Romania. The city is located north of Bucharest. In 2002, it had a population of 232,527, making it the ninth-largest city in Romania.-History:The town was established in 1596, during the reign of Mihai...
),
RomaniaRomania is a country located in Southeastern and Central Europe, North of the Balkan Peninsula, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea. Almost all of the Danube Delta is located within its territory...
, in 1856-1857, with US investment. After being taken over by
Nazi GermanyNazi Germany and the Third Reich are the common English names for Germany between 1933 and 1945, while it was led by Adolf Hitler and the National Socialist German Worker's Party . The name Third Reich refers to the state as the successor to the Holy Roman Empire of the Middle Ages and the German...
, the Ploesti refineries were bombed in Operation Tidal Wave by the Allies during the
Oil Campaign of World War IIThe Allied Oil Campaign of World War II bombed facilities supplying Nazi Germany with petroleum, oil, and lubrication products; striking targets in Germany and "Axis Europe"; including refineries for natural oil, plants producing synthetic oil, storage depots, and other POL chemical works...
. Another early large refinery is Oljeön,
SwedenSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...
(1875), now preserved as a museum at the
UNESCOThe United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations established on 16 November 1945...
world heritage siteA UNESCO World Heritage Site is a site that is on the list that is maintained by the international World Heritage Programme administered by the UNESCO World Heritage Committee, composed of 21 state parties which are elected by their General Assembly for a four-year term.A World Heritage Site is a...
EngelsbergEngelsberg Ironworks is an ironworks in Ängelsberg, a village in Fagersta Municipality in Västmanland, Sweden. It was built in 1681 by Per Larsson Gyllenhöök and developed into one of the world's most modern ironworks in the period 1700-1800. It is listed as a UNESCO world heritage site since...
and part of the Ecomuseum Bergslagen.
At one point, the refinery in
Ras TanuraRas Tanura is a city in the Eastern Province of Saudi Arabia located on a peninsula extending into the Persian Gulf...
,
Saudi ArabiaSaudi Arabia , is an Arab country and the largest country of the Arabian Peninsula. It is bordered by Jordan on the northwest, Iraq on the north and northeast, Kuwait, Qatar, Bahrain, and the United Arab Emirates on the east, Oman on the southeast, and Yemen on the south...
owned by
Saudi AramcoSaudi Aramco is the state-owned national oil company of Saudi Arabia. It is the largest oil corporation in the world with the largest proven crude oil reserves and production. Headquartered in Dhahran, Saudi Arabia, Saudi Aramco also operates the world's largest single hydrocarbon network, the...
was claimed to be the largest oil refinery in the world. For most of the 20th century, the largest refinery was the
Abadan RefineryThe Abadan refinery is located in Abadan near the coast of the Persian Gulf. It was completed in 1912 and was one of world's largest oil refineries when it was destroyed in 1980 by Iraq in the Iraq-Iran war. The refinery had a capacity of 635,000 b/d in 1980 and formed a refinery complex with...
in
IranIran , officially the Islamic Republic of Iran is a country in Western Asia. The name Iran has been in use natively since the Sassanid period and came into international use from 1935, before which the country was known internationally as Persia...
. This refinery suffered extensive damage during the
Iran-Iraq warThe Iran–Iraq War, also known as the Imposed War and Holy Defense in Iran, and Saddām's Qādisiyyah in Iraq, and the First Gulf War , was a war...
. The world's largest refinery complex is the "Centro de Refinación de Paraguaná" (CRP) operated by PDVSA in Venezuela with a production capacity of (Amuay , Cardón and Bajo Grande 16,000 bpd). SK Energy's
UlsanUlsan, officially the Ulsan Metropolitan City, is South Korea's seventh largest metropolis with a population of over 1.1 million. It is located in the south-east of the country, neighboring Busan to the south and facing the Sea of Japan to the east.Ulsan is the industrial powerhouse of South...
refinery in
South KoreaSouth Korea, officially the Republic of Korea and often simply referred to as Korea, is a country in East Asia, located on the southern half of the Korean Peninsula. It is neighbored by China to the west, Japan to the east, and North Korea to the north. Its capital is Seoul, the second largest...
with a capacity of and
Reliance PetroleumReliance Petroleum Limited was set up by Reliance Industries Limited , one of India's largest private sector companies. Currently, RPL is subsidiary of RIL. RPL also benefits from a strategic alliance with Chevron India Holdings Pte Limited, Singapore, a wholly owned subsidiary of Chevron...
's
Jamnagar RefineryThe Jamnagar Refinery is a private sector crude oil refinery owned by Reliance Industries Limited in Jamnagar, India. The refinery was commissioned on 14 July 1999 with an installed capacity of...
in
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
with are the second and third largest, respectively.
Oil refining in the United States
Early refineries in the U.S. processed crude oil to recover the
keroseneKerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin, is a combustible hydrocarbon liquid. The name is derived from Greek keros...
. Other products (like gasoline) were considered wastes and were 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. Refineries pre-dating the
US Environmental Protection AgencyThe U.S. Environmental Protection Agency is an agency of the federal government of the United States charged to regulate chemicals and protect human health by safeguarding the natural environment: air, water, and land...
(EPA) were not subject to any environmental protection regulations. 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. Some attribute increasing dependence in the U.S. on imports of finished gasoline, to lack of new refineries. On the other hand, studies have revealed that accelerating mergers among the refineries have further reduced capacity, resulting in tighter markets particularly in the U.S.
See also
- Air pollution
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment, into the atmosphere....
- AP 42 Compilation of Air Pollutant Emission Factors
The AP 42 Compilation of Air Pollutant Emission Factors, was first published by the U.S. Public Health Service in 1968. In 1972, it was revised and issued as the second edition by the U.S. Environmental Protection Agency . In 1985, the subsequent fourth edition was split into two volumes...
- API oil-water separator
An API oil-water separator is a device designed to separate gross amounts of oil and suspended solids from the wastewater effluents of oil refineries, petrochemical plants, chemical plants, natural gas processing plants and other industrial sources...
- Industrial wastewater treatment
Industrial wastewater treatment covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use....
- Cooling tower
Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the ...
- Ethanol fuel
Ethanol fuel is ethanol , the same type of alcohol found in alcoholic beverages. It can be used as a fuel, mainly as a biofuel alternative to gasoline, and is widely used by flex-fuel light vehicles in Brazil, and as an oxygenate to gasoline in the United States. Together, both countries were...
- Gas flare
A gas flare or flare stack is an elevated vertical stack or chimney found on oil wells or oil rigs, and in refineries, chemical plants and landfills used for burning off unwanted gas or flammable gas and liquids released by pressure relief valves during unplanned over-pressuring of plant equipment...
- List of oil refineries
- Nelson complexity index
The Nelson complexity index was developed by Wilbur L. Nelson in a series of articles in Oil & Gas Journal in 1960-61 . In 1976, he elaborated on the concept in another series of articles, again in Oil & Gas Journal...
- Refinery
A refinery is a production facility composed of a group of chemical engineering unit processes and unit operations refining certain materials or converting raw material into products of value.-Types of refineries:Different types of refineries are as follows:...
- Acid gas
Acid gas is natural gas or any other gas mixture which contains significant amounts of hydrogen sulfide , carbon dioxide , or similar contaminants. The terms acid gas and sour gas are often incorrectly treated as synonyms...
- Sour gas
Sour gas is natural gas or any other gas containing significant amounts of hydrogen sulfide . Natural gas is usually considered sour if there are more than 5.7 milligrams of H2S per cubic meter of natural gas, which is equivalent to approximately 4 ppm by volume...
External links