Refinery
Arefineryis a production facility composed of a group ofchemical engineeringunit processesandunit operationsrefiningcertain materials or convertingraw materialinto products of value.
Types of refineries
[edit]Different types of refineries are as follows:
- Petroleum oil refinery,which convertscrude oilintohigh-octanemotor spirit (gasoline/petrol),diesel oil,liquefied petroleum gases(LPG),kerosene,heatingfuel oils,hexane,lubricating oils,bitumen,andpetroleum coke
- Edible oil refinerywhich convertscooking oilinto a product that is uniform in taste, smell and appearance, and stability
- Natural gas processingplant, which purifies and converts raw natural gas into residential, commercial and industrial fuel gas, and also recoversnatural gas liquids(NGL) such asethane,propane,butanesandpentanes
- Sugar refinery,which convertssugarcane and sugar beets into crystallized sugar and sugar syrups
- Salt refinery,which cleans common salt (NaCl), produced by thesolar evaporationof sea water, followed by washing andre-crystallization
- Metal refineries refining metals such asalumina,copper,gold,lead,nickel,silver,uranium,zinc,magnesiumandcobalt
- Iron refining, a stage of refiningpig iron(typically grey cast iron to white cast iron), beforefining,which converts pig iron into bar iron or steel[1]
A typical oil refinery
[edit]The image below is a schematicflow diagramof a typical oil refinery depicting various unit processes and the flow of intermediate products between the inletcrude oil feedstockand the final products. The diagram depicts only one of the hundreds of different configurations. It does not include any of the usual facilities providing utilities such as steam, cooling water, and electric power as well asstorage tanksfor crude oil feedstock and for intermediate products and end products.[2][3][4][5][6]
Natural gas processing plant
[edit]The image below is a schematicblock flow diagramof a typical natural gas processing plant. It shows various unit processes converting raw natural gas into gas pipelined to end users.
The block flow diagram also shows how processing of the raw natural gas yields byproduct sulfur, byproduct ethane, and natural gas liquids (NGL) propane, butanes and natural gasoline (denoted as pentanes +).[7][8][9][10][11]
Sugar refining
[edit]Sugar is generally produced fromsugarcaneorsugar beets.As the global production of sugar from sugarcane is at least twice the production from sugar beets, this section focuses on sugarcane.[12]
Milling
[edit]
Sugarcane is traditionally refined into sugar in two stages. In the first stage, raw sugar is produced by the milling of harvested sugarcane. In a sugar mill, sugarcane is washed, chopped, and shredded by revolving knives. The shredded cane is mixed with water and crushed. The juices (containing 10-15 percentsucrose) are collected and mixed withlimeto adjustpHto 7, prevent decay intoglucoseandfructose,and precipitate impurities. The lime and other suspended solids are settled out, and the clarified juice is concentrated in amultiple-effect evaporatorto make a syrup with about 60 weight percent sucrose. The syrup is further concentrated undervacuumuntil it becomessupersaturatedand is then seeded withcrystallinesugar. Upon cooling, sugar crystallizes out of the syrup.Centrifugingthen separates the sugar from the remaining liquid (molasses). Raw sugar has a yellow to brown color. Sugar is sometimes consumed locally at this stage but usually undergoes further purification.[13]Sulfur dioxideis bubbled through the cane juice subsequent to crystallization in a process known as "sulfitation". This process inhibits color forming reactions and stabilizes the sugar juices to produce "mill white" or "plantation white" sugar.
The fibrous solids, calledbagasse,remaining after the crushing of the shredded sugarcane are burned for fuel which helps a sugar mill to become self-sufficient in energy. Any excess bagasse can be used for animal feed, to produce paper, or burned to generate electricity for the local power grid.
Refining
[edit]
The second stage is often executed in heavy sugar-consuming regions such asNorth America,Europe,andJapan.In the second stage, white sugar is produced that is more than 99 percent puresucrose.In such refineries, raw sugar is further purified byfractional crystallization.
References
[edit]- ^A HISTORY OF METALLURGY,2nd edition, 1992, R. F. Tylecote,ISBN1-902653-79-3,p.126
- ^Gary, J.H. & Handwerk, G.E. (1984).Petroleum Refining Technology and Economics(2nd ed.). Marcel Dekker, Inc.ISBN0-8247-7150-8.
- ^Guide to RefiningArchived2006-08-08 at theWayback MachinefromChevron Oil's website
- ^Refinery flowchartArchived2006-06-28 at theWayback MachinefromUniversal Oil Products' website
- ^An example flowchartArchived2005-12-22 at theWayback Machineof fractions from crude oil at a refinery
- ^Gunter Alfke, Walther W. Irion & Otto S. Neuwirth (2007). "Oil Refining".Ullmann's Encyclopedia of Industrial Chemistry.doi:10.1002/14356007.a18_051.pub2.ISBN978-3527306732.
- ^Natural Gas Processing: The Crucial Link Between Natural Gas Production and Its Transportation to MarketArchived2011-03-04 at theWayback Machine
- ^Example Gas Plant Flow Diagram
- ^From Purification to Liquefaction Gas ProcessingArchived2010-01-15 at theWayback Machine
- ^Feed-Gas Treatment Design for the Pearl GTL Project
- ^Benefits of integrating NGL extraction and LNG liquefaction
- ^Hubert Schiweck; Margaret Clarke; Günter Pollach (2007). "Sugar".Ullmann’s Encyclopedia of Industrial Chemistry.Weinheim: Wiley-VCH.doi:10.1002/14356007.a25_345.pub2.ISBN978-3527306732.
- ^Shore, M.; Broughton, N.W.; Dutton, J.V.; Sissons, A. (1984)."Factors affecting white sugar colour"(PDF).Sugar Technology Reviews.12:1–99.
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