A process for the purification of fossil fuels by gasification of solid by means of steam under oxygen under pressure gases generated

摘要

1483038 Purifying combustible gases METALLGESELLSCHAFT AG 8 July 1975 [10 July 1974] 28783/75 Heading C5E A process for purifying a gas produced by the gasification of a solid or liquid fossil fuel in the presence of steam and/or oxygen under superatmospheric pressure, which process serves to remove catalyst poisons and to desulphurize the gas and provides an exhaust gas rich in hydrogen sulphide, involves indirectly cooling the crude gas to ambient temperature, separating and removing the condensed hydrocarbons from the gas, subsequently scrubbing the gas with water to remove ammonia in a first scrubbing stage, in which the water rate is controlled to be just sufficient to remove the ammonia, scrubbing the gas with an organic solvent having a boiling point of at least 127‹ C. at 1 bar, which solvent is miscible with water and to which sulphur is added, in a second scrubbing stage, the ratio by volume of solvent to gas being controlled in dependence upon the solubility in the solvent of methylmercaptan so that the latter is removed from the gas, subsequently scrubbing the gas in a third scrubbing stage with a scrubbing agent comprising the organic solvent and water, the water content being 5 to 30 mole per cent, whereby hydrogen sulphide and carbon oxysulphide are substantially entirely and selectively removed from the gas, separately regenerating the scrubbing agents from the second and third scrubbing stages and recycling the regenerated scrubbing agents to the second and third scrubbing stages respectively for re-use. Organic solvents: N- methyl pyrrolidone, sulpholane, butyrolactone, morpholine, N-methyl-#-caprolactam or polyglycolether. Sulphur may be added to the scrubbing agent in the second scrubbing stage through the reaction of the hydrogen sulphide contained in the gas leaving the first scrubbing stage with the oxygen which is present, such sulphur addition amounting to from 0À1 to 10 g. per litre of scrubbing liquid. A soluble activator exemplified by 1,2-dimethylimidazole, may be included in the scrubbing liquid for the third scrubbing stage in an amount of 1 to 20% by weight.