Self-regulating process for removal of hydrogen sulfide from gases

Claim 1

A self-regulating process for removing hydrogen sulfide from a hydrogen sulfide-containing gas stream comprising the steps of: a) scrubbing said gas stream with an aqueous solution of sulfur dioxide whereby essentially all of the sulfur dioxide in said aqueous solution is reacted with a portion of the hydrogen sulfide contained therein to form sulfur and water, and the remaining portion of the hydrogen sulfide remains unreacted; b) then scrubbing said gas stream with an absorbent to remove essentially all of the remaining hydrogen sulfide to form an essentially hydrogen sulfide free gas stream and a hydrogen sulfide rich absorbent; c) desorbing said hydrogen sulfide from said hydrogen sulfide rich absorbent to obtain a lean absorbent which is recycled to the hydrogen sulfide absorbent step (b), and a hydrogen sulfide stream; d) Oxidizing said hydrogen sulfide stream to form sulfur dioxide, and dissolving said sulfur dioxide in an aqueous medium to form an aqueous solution of sulfur dioxide and; e) using said aqueous solution of sulfur dioxide as the scrubbing solution in step (a), essentially all of said aqueous solution of sulfur dioxide being used in step (a) and comprising essentially the sole source of sulfur dioxide used in said step; Whereby the amount of hydrogen sulfide which remains after step (a) to be converted to sulfur dioxide is self-regulated so that the reaction between the sulfur dioxide and that portion of the hydrogen sulfide which is not converted to sulfur dioxide to form sulfur and water has the overall effect of consuming essentially all of the hydrogen sulfide contained in the original gas stream.