METHOD FOR SELECTIVELY REMOVING HYDROGEN SULFIDE FROM GAS MIXTURES CONTAINING CARBON DIOXIDE AND HYDROGEN SULFIDE

摘要

A process for selectively absorbing H2S from gas mixtures which contain CO2 and H2S in a molar ratio of 4:1 or greater and in which the gas flow rate varies substantially. Alkali metal carbonate solutions are used with absorption under pressure and at an elevated temperature and desorption by steam stripping at about atmospheric pressure. The degree of selectivity of H2S removal is maintained constant despite substantial variations in the gas flow rate by maintaining a constant stripping steam/gas ratio selected to provide the desired partial pressure of H2S in the purified gas and by adjusting the solution/gas ratio to a value in the vicinity of that at which the partial pressure of H2S in the purified gas remains at said selected value while the difference between the partial pressures of CO2 and H2S in the purified gas reaches a maximum value, and by then maintaining such solution/gas ratio as the gas flow rate varies. The process is particularly applicable to H2S removal from hot gases produced by the pressure gasification of sulfur-containing coal, oil or the like which are to be used in power generation cycles.