Processing Petroleum Essay Example | Topics and Well Written Essays - 1500 words

Processing Petroleum - Essay Example The specific molecular makeup of crude oil varies from location to location as mentioned above however the chemical elements required to form crude oil vary over a fairly narrow margin. (Speight, 1999) The major hydrocarbon components of crude oil include paraffins, naphthenes, aromatics and asphaltics which display consistency in their presence in crude oil. The variation in these hydrocarbon components determines the exact properties of the crude oil in question. (Hyne, 2001) Crude oil contains a number of lighter more usable factions such as HFO, LFO, diesel, gasoline and a number of components for isomers of various kinds, asphalt etc. These factions can only be separated if crude oil is subjected to various processes. The processes used to separate factions of crude oil are better known collectively as petroleum refining and fractional distillation is a critical process. Fractional distillation relies on the physical property of different liquids to boil out at specific temperat ures only. Since crude oil is a mixture of various different lighter oils and solids, the constituents all tend to turn to vapour at different temperatures. Once these temperatures are achieved, the particular faction in question is collected downstream and is thus separated from crude oil’s other constituents. Processes carried out in Oil Refineries The crude oil that is brought in from an oil field is separated into various useful constituents through a variety of different techniques. Not only are the constituents of crude oil separated but they are often treated into different other useful products as well. The entire process begins in the crude oil distillation unit (CDU). All forms of oil refineries possess a CDU which intimates the separation. More separation may be carried out after the CDU too. The basic job of the CDU is to distil various larger constituents in crude oil into smaller more easily processed factions. The CDU for most oil refineries is operated at or a round atmospheric pressure (760 mm Hg) so the CDU is also referred to as the atmospheric distillation unit. (Kister, 1992) The crude oil is at ambient temperature when it is introduced into the refining process so it needs to be heated before separation. This is done by heating the crude oil with the lighter fractions of oil that have already been distilled as they already contain a lot of heat. The heated crude oil is then taken through a process where any inorganic salts are removed from it. Typically the crude oil contains a sizable amount of sodium chloride and it is removed. After the salt has been removed from the crude oil, it is then heated again by exchanging heat with other distilled fractions of oil. This stage is better known as pre-heating because the crude oil does not reach a temperature where the fractions begin to separate. The heat required to begin the process of fractional distillation is gathered through a fuel fired furnace in which fuel is combusted to produce large amounts of heat. The heat produced in this manner is generally around 398oC in temperature and the stream is then fed to the bottom most section of the distillation unit or column. As the crude oil is heated and various fractions separate from it there is a need to cool those fractions to liquefy