Coal into coke, conversion

Figure I. Conversion of coal into coke according to Echterhoff and Mackow-sky (5). Photographs 1, 3, 4, 8, 12, 18, and 21 9.5 X. Photographs 2, 5, 6,...

The pyrolytic conversion of coal into coke, gas and aromatic liquid products is the oldest and, in quantitative terms, most important coal-refining process. In the absence of air, carbonization processes are considered to occur in stages up to 150 °C, carbon dioxide, water and volatile C2 to C4 hydrocarbons are evolved. At pyrolysis temperatures above 180 °C the volatile components also contain aromatics. At temperatures in excess of 350 °C, rapid degasification occurs, which continues to around 550 °C, leading to semi-coke. The rate of degasification approximately follows a reaction of the 1st order, which can be explained by the rupture of the bonds of the macromolecules in the coal. In the secondary degasification of the semi-coke (600 to 800 °C) hydrogen and methane are the main products. 

Gas Retort. A reffaetory structure used for the conversion of coal into coke with the simultaneous distillation of town gas. There are two types continuous vertical RETORT (q.v.) and horizontal RETORT (q.v.). In the UK the reffactories used must meet the spedfications issued by the Gas Council (1 Grosvenor Place, London, S.W.1) in collaboration with the Society of British Gas Industries and the British Coking Industry Association. 

Ash, as determined by the standard test method (ASTM D-3174), is the residue remaining after burning the coal and coke and differs in composition from the original inorganic constituents present in the coal. Incineration causes an expulsion of all water, the loss of carbon dioxide from carbonates, the conversion of iron pyrites into ferric oxide, and other chemical reactions. In addition, the ash, as determined by this test method, will differ in amount from ash produced in furnace operations and other firing systems because incineration conditions influence the chemistry and amount of the ash. 

Hence, with electricity generated by conventional means, the net primary energy consumption is very high at over three times the fuel value of acetylene, whereas use of hydroelectric power could possibly make acetylene production competitive. (Any energy losses in the conversion of coal, as mined, into coke have been ignored.)... 

Direct Carbon Fuel Cells (DCFC). In direct carbon fuel cells, solid carbon (presumably a fuel derived from coal, pet-coke or biomass) is used directly in the anode, without an intermediate gasification step. Concepts with solid oxide, molten carbonate, and alkaline electrolytes are all under development. The thermodynamics of the reactions in a DCFC allow very high efficiency conversion. Therefore, if the technology can be developed into practical systems, it could ultimately have a significant impact on coal-based power generation. 

Some chemical processes use energy directly to drive the transformation. For example, the conversion of iron ore, iron oxide, to iron metal requires chemical energy to remove the oxygen atoms. In early times the iron ore was heated with charcoal in more recent times it is heated with refined coal (coke), but in both cases the result is conversion of coal or wood into carbon monoxide, which is toxic but can be burned to carbon dioxide to generate needed heat. There is now interest in devising processes that do not use carbon in this way, but use electrical energy to avoid the production of carbon oxides. 

Nearly simultaneous wl th the earliest improvements in the manufacture of east-iron by ptea B of pit-coal,1 were, others of, an equally important kind, for converting the cast-iron, into malleable or bar-iron. Hitherto this had been effected. by means. of wopd charooal in what are, termed refiners, aq ft. stiff practised In the, South of. France but owing to the scarcity, of wood foal in. this country, the, charcoal was mixed up with coke, for the refining operation the iron produced from. this was hard and of an inferior quality, and much time was required for the conversion of a ton of cast into malle-... 

Carbonization the conversion of an organic compound into char or coke by heat in the substantial absence of air often used in reference to the destructive distillation (q.v.) (with simultaneous removal of distillate) of coal. 

Ethjdene can be converted by simple hydration into alcohol. The process is catatytic and occurs by way of the intermediate ethyl sulphuric add, C2H6HSO4, and given a large supply of eth.3dene, the conversion into alcohol does not offer great difficulties. Its recovery from coal gas in this way is therefore theoretically possible, and Bury, at Skinningrove Coke Oven Works, has obtained i-6 gallons per ton of coal carbonized from rims of 5800 tons of coal carbonized per week Chemical Age, 1919, i, 714). 

The second project is at Carson in California where the feed material for conversion to hydrogen will be petroleum coke (50001 per day) from a BP refinery. After reforming, the hydrogen will supply a 500 MW power station and the carbon dioxide (4Mt per year) will be pumped into an on-shore oil field. This plant should be on-stream early in the next decade. It has since been announced that General Electric is to link with BP with a view to building at least five such clean-coal electricity plants in the USA, with Carson being the first. 

Thermal Plasma Conversion of CoaL Compare production of CO and CO2 by oxidation of coke in reactions (10-32) and (10-33) in thermal plasma conditions. Taking into accormt relation (10-34) between the coke oxidation rate coefficients, calculate temperatures at which CO and CO2 production becomes equal at relatively low and relatively high pressures. 

Another process for pelletizing caking coal fines and carbonizing the pellets involves the conversion of caking coal fines into pellets. In the second stage, the pellets are coated with hematite ore (Fe203) and the ore-covered pellets are then coked whereupon soften and sinter together to form a... 

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