The word "coal" came from Anglo-Saxon col, which meant charcoal. Coal was not mined in Britain before the late Middle Ages; i.e. after ca. 1000 AD. Mineral coal was referred to as sea-coal, either because it was found on beaches occasionally having fallen from the exposed coal seams above or washed out of underwater coal seam outcrops, or because it was easier to transport by sea rather than on the very poor road system. Coal is formed from plant remains that have been compacted, hardened, chemically altered, and metamorphosed by heat and pressure over geologic time. Coal was formed in swamp ecosystems. These swamp environments were formed during slow subsidence of passive continental margins, and most seem to have formed adjacent to estuarine and marine sediments suggesting that they may have been in tidal delta environments. When plants die in these peat swamp environments, their biomass is deposited in anaerobic aquatic environments where low oxygen levels prevent their complete decay by bacteria and oxidation.
[...] As the coal gravitates down ward and is heated, devolatization commences and, for a temperature of 620 to 760 0c devolatization is accompanied by gasification of the resulting char. The crude gas leaves the gasifier at temperatures between 375 and 595 0c, depending upon the type of coal. It contains carbonization products such as tar, oil, naphtha, phenols, ammonia, and traces of ash dust. The crude gas is passed through scrubber where it is washed by circulating gas liquor and then cooled to temperature at which the gas is saturated with steam. [...]
[...] Sasol in South Africa uses coal as a feedstock, and produces a variety of synthetic petroleum products. The process is today used in South Africa to produce most of the country's diesel fuel from coal by the company Sasol. The process was used in South Africa to meet its energy needs during its isolation under Apartheid. Bergius process: The Bergius Process is a method of getting liquid hydrocarbons for use as synthetic fuel from lignite by hydrogenation. It was first discovered by Friedrich Bergius in 1921. [...]
[...] The process is as following: The by-product in the hydraulic main first go via the foul main through a primary condenser and a baffled tar extractor, where the coke oven gas is separated from the ammonia liquor and the coal tar. The gas its ammonium removed as ammonium sulfate by bubbling through sulfuric acid. Coal tar products such as benzene, toluene, and some naphthalene are scrubbed by straw oil in a paced light oil tower or scrubber. These are largely for fuel gas main steel plant operation and may be used for under firing coke ovens themselves. [...]
[...] Here we use a narrow chamber, usually about 11to 12 m long m high, tampering in width from 0.4 to 0.6 at end to 0.35 to 0.4 m at the other. Capacity of these ovens is 15 to 25 tones of coal. In the equipment the wall temperature is maintained at 1100 0c, the flue gas temperature is 1290 0c and the temperature at the centre of the charge is 980 0c Coke oven gas is now produced by Coking of coal using and is obtained as a byproduct in this operation. [...]
[...] The utility of the process is primarily in its role in producing fluid hydrocarbons or hydrogen from a solid feedstock, such as coal or solid carbon-containing wastes of various types. If liquid petroleum-like fuel, lubricant, or wax is required, the Fischer-Tropsch process can be applied. Finally, if hydrogen production is to be maximized, the water gas shift reaction can be performed, generating only carbon dioxide and hydrogen and leaving no hydrocarbons in the product stream. Fortunately shifts from liquid to gaseous fuels are relatively easy to make. [...]
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