Procedure for Obtaining a Gaseous Mixture with High Methane Content from Coal

摘要

A procedure is described for obtaining a gaseous mixture with high methane content from coal including the following stages:a) crushing of the coal so as to have coal particle size of not more than 5 cm, whereby coal particles larger than 0.5 mm constitute at least 70% of the total;b) addition to the crushed coal of one or morealkaline compounds where the ion and alkaline ions are of a quantity between 4 and 20% of the weight in relation to the dry coal without ash and possible subsequent drying of the coal containing the additive;c) gasification of the coal containing the additive and methanization of the gas generated in a single stage with a fixed bed of coal sloping downwards against the current with steam and air present in a quantity not greater than 35% in weight in relation to the dry coal without ash and/or essentially pure oxygen in a quantity not greater than 25% in weight in relation to the dry coal without ash, operating at a pressure greater than 25 atmospheres and at a temperature varying between 400 and 850 degrees C, preferably between 450 and 750 degrees C;d) removal from the gas generated in stage c) of the steam which did not react and of the condensate compounds formed;e) removal of the acid gases from the gaseous mixture obtained with a high methane content.