Recovery of hydrogen sulfide formed during black liquor gasification

A process, in which the hydrogen sulfide formed during black liquor gasifi cation is absorbed into green liquor, was assessed. In particular, the stoichiometry and equilibria of the pertinent reactions were examined. The process was determined to be feasible at elevated pressures, except possibly for gasification processes with low yields of hydrogen sulfide . A condition is that, in the absorber, the mass transfer resistance in the gas phase is low. In all cases, the predicted lime requirement for recausticization of the final green liquor was higher than that of the conventional recovery process. Implications for the mill energy balance were evaluated.