BLACK LIQUOR GASIFICATION PROCESS AND REGENERATION OF PULPING LIQUOR

摘要

The black liquor (10) from a kraft pulping process is gasified in a fluidizedbed reactor (12) in the presence of solid calcium compounds (CaO, CaCO3,Ca(OH)2) which react with the sulfur compounds (H2S, COS) to produce solidCaS. The solid CaS along with the other primary solids (Na2CO3, Na2S) areremoved (18) from the reactor (12) and processed to form one or more whiteliquor streams for recycle to the pulping process. In this processing, theNa2CO3 and Na2S are dissolved (72) to form green liquor and the CaS is reacted(78) with NaOH to form NaHS. The causticizing of the green liquor may beseparate from or combined with the conversion of the CaS in the green liquorto form a single white liquor stream (104) or the CaS may be separated fromthe green liquor and processed entirely separately to form a second highsulfide white liquor stream (174).