GB309116A - A process for removing ammonia and sulphuretted hydrogen from gases - Google Patents

Abstract

309,116. Hansen, C. J., (Assignee of Koppers Akt.-Ges., H.). April 5, 1928, [Convention date]. Drawings to Specification. Materials for purifying gas; purifier waste, revivefying.-Ammonia and hydrogen sulphide are removed from gases, e.g. coal distillation gases containing them in ratios less than 2:1 by scrubbing with a single liquor comprising iron or manganese thionate in solution and the hydroxide of the metal in suspension. So that the ratios of the iron in thionate form to that in the form of hydroxide may correspond to that between the hydrogen sulphide removable with ammonia to that in excess in the gas, the latter ratio, x :y, is determined by analytical test and the spent liquor is divided into two portions in the ratio 3x: 2y, these proportions of liquor required as thionate and hydroxide respectively being indicated by the equations of the scrubbing and regenerating reactions. The first portion is treated with sulphurous acid and the second is oxidized with air or other oxygen-containing gas, the two liquors then being returned to the scrubbing apparatus. Liquor to be worked up into ammonium sulphate and sulphur is freed from dissolved iron or manganese by treatment with the crude gas. Ammonia may be previously removed by cooling or cooling and washing with water in which case the iron-freeing operation may be effected by running the liquor through a scrubbing tower through which ammonia vapours obtained by distilling the condensate or ammonia wash liquor and containing hydrogen sulphida are passed. Ammonia from other sources may supplement that in the gas.