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Oil refinery

2007 Schools Wikipedia Selection. Related subjects: Business

   View of Shell Oil Refinery in Martinez, California.
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   View of Shell Oil Refinery in Martinez, California.

   An oil refinery is an industrial process plant where crude oil is
   processed and refined into useful petroleum products, such as gasoline
   and diesel fuel.

Operation

   Crude oil is separated into fractions by fractional distillation. The
   fractionating column is cooler at the top than at the bottom so the
   vapours can condense more easily while moving up the column. The
   heavier fractions that emerge from the bottom of the fractionating
   column are often broken up (cracked) to make more useful products.
   Enlarge
   Crude oil is separated into fractions by fractional distillation. The
   fractionating column is cooler at the top than at the bottom so the
   vapours can condense more easily while moving up the column. The
   heavier fractions that emerge from the bottom of the fractionating
   column are often broken up ( cracked) to make more useful products.

   Raw oil or unprocessed ("crude") oil is not very useful in the form it
   comes in out of the ground. Although "light, sweet" (low viscosity, low
   sulfur) oil has been used directly as a burner fuel for steam vessel
   propulsion, the lighter elements form explosive vapors in the fuel
   tanks and so it is quite dangerous, especially so in warships. For this
   and many other uses, the oil needs to be separated into parts and
   refined before use in fuels and lubricants, and before some of the
   byproducts could be used in petrochemical processes to form materials
   such as plastics, and foams. Petroleum fossil fuels are used in ship,
   automobile and aircraft engines. These different hydrocarbons have
   different boiling points, which means they can be separated by
   distillation. Since the lighter liquid elements 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 using complex and energy intensive processes.

   Oil can be used in so many various ways because it contains
   hydrocarbons of varying molecular masses, forms and lengths such as
   paraffins, aromatics, naphthenes (or cycloalkanes), alkenes, dienes,
   and alkynes. Hydrocarbons are molecules of varying length and
   complexity made of only hydrogen and carbon atoms. Their various
   structures give them their differing properties and thereby uses. The
   trick in the oil refinement process is separating and purifying these.

   Once separated and purified of any contaminants and impurities, the
   fuel or lubricant can be sold without any further processing. Smaller
   molecules such as isobutane and propylene or butylenes can be
   recombined to meet specific octane requirements of fuels by processes
   such as alkylation or less commonly, dimerization. Octane grade of
   gasoline can also be improved by catalytic reforming, which strips
   hydrogen out of hydrocarbons to produce aromatics, which have much
   higher octane ratings. 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.

Products of oil refineries

     * Asphalt
     * Diesel fuel
     * Fuel oils
     * Gasoline
     * Kerosene
     * Liquid petroleum gas (LPG)
     * Lubricating oils
     * Paraffin wax
     * Tar

Safety and environmental concerns

   MiRO refinery at Karlsruhe
   Enlarge
   MiRO refinery at Karlsruhe

   Oil refineries are typically large sprawling industrial complexes with
   extensive piping running throughout. The refining process releases
   numerous different chemicals into the atmosphere; consequently, there
   are substantial air pollution emissions and a notable odour normally
   accompanies the presence of a refinery. Aside from air pollution
   impacts there are also wastewater concerns, upset risks of fire and
   explosion, and both occupational noise and environmental noise health
   effects.

   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 facility in 1976. However, many existing
   refineries have been expanded during that time. Environmental
   restrictions and pressure to prevent construction of new refineries
   have also contributed to rising fuel prices in the United States.

   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 Tenerife,
   Spain , which is sited in a densely-populated city centre 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 and associated chemical plants are adjacent to
   urban areas in Richmond, Martinez, California, Pacheco, Concord,
   Pittsburg, Vallejo and Benicia, with occasional accidental events that
   require "shelter in place" orders to the adjacent populations.

Common process units found in a refinery

     * Desalter Unit (washes out salt from the crude oil before it goes
       into the atmospheric distillation unit)
     * Atmospheric Distillation Unit (distills crude oil into fractions)
     * Vacuum Distillation Unit (further distills residual bottoms after
       atmospheric distillation)
     * Naphtha Hydrotreater Unit (desulfurizes naphtha from atmospheric
       distillation. Must hydrotreat the naphtha before sending to a
       Catalytic Reformer Unit.)
     * Catalytic Reformer Unit (contains catalyst used to convert the
       naphtha-boiling range molecules into higher octane reformate
       (reformer product). The reformate has higher content of aromatics,
       olefins, and cyclic hydrocarbons). An important byproduct of a
       reformer is hydrogen released during the catalyst reaction. The
       hydrogen is used either in the hydrotreaters and hydrocracker.)
     * Distillate Hydrotreater Unit (desulfurizes distillate (diesel)
       after atmospheric distillation)
     * Fluid Catalytic Cracking (FCC) Unit (upgrades heavier fractions
       into lighter, more valuable products)
     * Hydrocracker Unit (upgrades heavier fractions into lighter, more
       valuable products)
     * Coking unit (processes asphalt into gasoline and diesel fuel,
       leaving coke as a residual product)
     * Alkylation unit (produces high octane component for gasoline
       blending)
     * Dimerization Unit
     * 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 for propane and similar gaseous fuels
       at pressure sufficient to maintain in liquid form - these are
       usually spherical or bullets (horizontal cylinder with rounded
       ends).
     * Storage tanks for crude oil and finished products, usually
       cylindrical, with some sort of vapor enclosure and surrounded by an
       earth berm to contain spills
     * Utility units such as cooling towers for circulating cooling water,
       boiler plants for steam generation, and wastewater collection and
       treating systems to make such water suitable for reuse or for
       disposal.

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, 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, used in the packaging of frozen foods, among others. May be
       shipped in bulk to a site to prepare as packaged blocks.
     * Sulfuric acid finishing and shipping. This is a useful industrial
       material, usually prepared and shipped as the acid precursor oleum,
       a byproduct of sulfur removal from fuels.
     * 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.

Co-plant siting

   Frequently a chemical plant will be sited adjacent to a refinery,
   utilizing intermediate products as feedstocks for the production of
   specialized materials such as plastics or agrichemicals.

History

   The world's first oil refinery opened at Ploieşti, Romania in 1856 .
   Several other refineries were built at that location with investment
   from United States companies before being taken over by Nazi Germany
   during World War II. Most of these refineries were bombarded by the US
   Air Force in Operation Tidal Wave, August 1, 1943. Since then they have
   been rebuilt, and currently pose somewhat of an environmental concern.

   Another early example is Oljeön, now preserved as a museum at the
   UNESCO world heritage site Engelsberg. It started operation in 1875 and
   is part of the Ecomuseum Bergslagen.

   It is difficult to exactly state which is largest oil refinery in the
   world. At one time this was claimed to be Ras Tanura, Saudi Arabia,
   owned by Saudi Aramco. For most of the 20th century, the largest
   refinery of the world was that of Abadan in Iran. This refinery
   suffered extensive damage in the IRAN/IRAQ war. The Guinness Book of
   World Records now (October 2006) records the BP Amoco refinery in Texas
   City, USA, as the refinery with the largest capacity (433,000
   barrels/day which is approximately 15,143,482 Imperial Gallon).

   Early US refineries processed crude oil to recover the kerosene. 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 EPA were very toxic
   to the environment. Strict legislation has mandated that refineries
   meet modern air and water cleanliness standards. In fact, obtaining a
   permit to build even a modern refinery with minimal impact on the
   environment (other than CO2 emmissions) is so difficult and costly that
   no new refineries have been built in the United States since 1976. As a
   result, the US is becoming more and more dependent on the imports of
   finished gasoline, as opposed to incremental crude oil.

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