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An oil 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 Fluid s between large Chemical Process ing units. OPERATION . The Fractionating Column is cooler at the top than at the bottom because the fractions at the top have lower Boiling Point s than the fractions at the bottom. The heavier fractions that emerge from the bottom of the fractionating column are often broken up ( Cracked ) to make more useful products. All of the fractions are subsequently routed to other refining units for further processing.]] Raw oil or unprocessed ("crude") oil is not 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 Plastic s, and Foam s. Petroleum Fossil Fuels are used in Ship , Automobile and Aircraft Engine s. These different Hydrocarbons have different Boiling Point s, 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 Mass es, forms and lengths such as Paraffin s, Aromatic s, Naphthene s (or Cycloalkane s), Alkene s, Diene s, and Alkyne s. Hydrocarbons are molecules of varying length and complexity made of only Hydrogen and Carbon Atom s. 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 Butylene s 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 Rating s. Intermediate products such as Gasoil s 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 Pressure s, and other properties to meet product specifications. Oil refineries are large scale plants, processing from about a hundred thousand to several hundred thousand Barrel s of crude oil per day. Because of the high capacity, many of the units are operated continuously (as opposed to processing in batches) at Steady State or approximately steady state for long periods of time (months to years). MAJOR PRODUCTS OF OIL REFINERIES Most products of oil processing are usually grouped into three categories: light distillates (LPG, gasoline, naptha), middle distillates (kerosene, diesel), heavy distillates and residuum (fuel oil, lubricating oils, wax, tar). This classification is based on the way crude oil is distilled and separated into fractions (called ) as can be seen in the above drawing.1
COMMON PROCESS UNITS FOUND IN A REFINERY
Flow diagram of typical refinery The image below is a schematic ' website An example flowchart of fractions from crude oil at a refinery SPECIALTY END PRODUCTS These will blend various Feedstock s, mix appropriate additives, provide short term storage, and prepare for bulk loading to trucks, barges, product ships, and railcars.
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 Plastic s or Agrichemicals . SAFETY AND ENVIRONMENTAL CONCERNS ]] The refining process releases numerous different chemicals into the 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, 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 Behind high gas prices: The refinery crunch . 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 '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. HISTORY The world's first oil refineries were set up by 's Kerosene Lamp gained popularity the refining industry grew in the area. The first large oil refinery opened at companies before being taken over by Nazi Germany during World War II . Most of these refineries were bombarded by US Army Air Forces 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 . At one time, the world's largest oil refinery 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 the Abadan refinery in Iran . This refinery suffered extensive damage during the war Iran-Iraq 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 956,000 barrels per day (Amuay 635,000 bpd, Cardón 305,000 bpd and Bajo Grande 16,000 bpd). SK Corporation's Ulsan refinery in South Korea with a capacity of 840,000 bpd and Reliance Petroleum's refinery in Jamnagar, India with 660,000 bpd are the second and third largest, respectively. 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 emissions) is so difficult and costly that no new refineries have been built (though many have been expanded) in the United States since 1976. As a result, some believe that this may be the reason that the US is becoming more and more dependent on the imports of finished gasoline, as opposed to incremental crude oil. On the other hand, studies have revealed that accelerating merger activity in the refining and production sector has reduced capacity further, resulting in tighter markets in the United States in particular. SEE ALSO
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