Removal of hydrogen sulfide from fluid streams with minimum production of solids

A continuous process for removing hydrogen sulfide from geothermal steam, comprising:

• condensing said geothermal steam in a first reaction zone with an aqueous solution of a pH range suitable for hydrogen sulfide removal to form a stream of non-condensable gases of reduced hydrogen sulfide content wherein said solution contains an effective amount of polyvalent metal chelate to convert said hydrogen sulfide to sulfur and to reduce said polyvalent metal chelate to a lower oxidation state, and an effective amount of sulfites to substantially convert said sulfur to soluble sulfur compounds;
• contacting said reduced polyvalent metal chelate with oxygen in a second reaction zone to reoxidize said polyvalent metal chelate;
• recirculating said reoxidized polyvalent metal chelate to said first reaction zone;
• incinerating the remainder of said hydrogen sulfide in said non-condensable gas stream to form sulfur dioxide;
• absorbing said sulfur dioxide with a scrubbing solution at conditions effective to form sulfites to substantially remove said sulfur dioxide;
• and
• supplying said sulfites from said absorption step to said first reaction zone.

In a continuous process for removing hydrogen sulfide from a fluid stream containing hydrogen sulfide which comprises:

• (a) contacting said stream in a first reaction zone with an aqueous solution at a pH range suitable for removing hydrogen sulfide, said solution containing an effective amount of a polyvalent metal chelate and an effective amount of an oxidizing agent capable of oxidizing elemental sulfur to soluble sulfur compounds whereby said hydrogen sulfide is converted to free sulfur and then to soluble sulfur compounds and said polyvalent metal chelate is reduced to a lower oxidation state metal chelate, (b) contacting said solution containing reduced polyvalent metal chelate in a second reaction zone with an oxygen containing gas stream whereby said metal chelate is continuously reoxidized, and (c) continuously recirculating said reoxidized solution back to said first reaction zone;
• the improvement comprising:
• incinerating hydrogen sulfide to form sulfur dioxide;
• selectively absorbing said sulfur dioxide in an alkaline aqueous solution without substantial carbon dioxide absorption to form a solution of sulfites essentially free of insoluble carbonates;
• and
• employing said sulfites as said oxidizing agent in said first reaction zone;
• wherein said aqueous solution in said first reaction zone is essentially free of insoluble carbonates.