| 摘要 |
A process is disclosed for producing a high methane content gas mixture from coal. In this process the coal is first ground to a particle size not greater than 5 mm, and preferably not larger than 2 mm. Then, one or more alkali and/or alkali-earth compounds are added to the ground coal, wherein the alkali or alkali-earth ions are in an amount within a range of from 4% to 20% by weight relatively to dry, ash-free coal. The additive-containing coal is possibly dried and possibly pelletized, so as to obtain pellets whose maximum dimension lies within the range of from 3 mm. to 5 cm. or preferably of from 3 mm to 2 cm. Then the additive-containing coal is gasified to produce gas from the coal and the so produced gas is subjected to methanation, in one single step with a fixed bed of countercurrently descending coal with steam, and in the presence of an amount of air not larger than 35% by weight, relatively to the ash-free dry coal and/or of an amount of essentially pure oxygen in an amount within the range of from 1 to 25% weight relatively to the ash-free dry coal. This gasification and methanation step is carried out at a pressure higher than 25 abs.atm and at a temperature of from 400 to 850.degree.C, preferably of from 450 to 750.degree.C. Then the unreacted steam and the condensible compounds that are formed are removed from the gas produced during the gasification and methanation step and finally the acidic gases are removed from the high methane content gas mixture that is obtained.
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