Flue Gas Desulfurization Scheme To Recover Elemental Sulfur

Abstract

A sodium-based flue gas desulfurization process, employing reductive burning and a Claus recovery system, has the advantage of producing elemental sulfur as a byproduct. This study optimized the process conditions for two steps in the proposed reaction scheme: (1) removing approximately one-sixth of the sulfur in the spent scrubbing liquor by a combination of acidification and evaporation and (2) precipitation of 50% of the remaining Na{sub 2}SO{sub 3}(s) by the addition of NaHCO{sub 3}/Na{sub 2}CO{sub 3} slurry. Several combinations of process conditions can be used to produce favorable results, but the optimum from a technical perspective is to add concentrated H{sub 2}SO{sub 4} to the spent liquor to 1.5% v/v, concentrate the mixture to 70% by weight, and then treat it with a >70% solids slurry of NaHCO{sub 3}/Na{sub 2}CO{sub 3}. The optimum from an economic perspective is dependent on the relative costs of H{sub 2}SO{sub 4} and the steam needed to concentrate the spent liquor.