US 5,292,440 AGranted

Removal of hydrogen sulfide from sour water without loss of heavy metal

AssigneeARI Technologies, Inc.

InventorLeslie C. Hardison

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Abstract

A process for removal of dissolved H.sub.2 S from condensed geothermal steam that includes the steps of cooling and oxygenating the sour steam condensate by contacting the sour condensate with air in a cooling tower; collecting the oxygenated condensate in a cooling tower collection basin and initially adding a polyvalent metal chelate catalyst, e.g., iron chelate catalyst solution, to the sour condensate at a very low concentration, e.g., about 0.1 ppm to about 10 ppm, preferably about 0.5 ppm to about 1 ppm by weight, and periodically or continuously adding, to the solution, a chelating agent for the polyvalent metal to account for chelon degradation to maintain active polyvalent metal chelate solution at a concentration of about 0.1 ppm to about 10 ppm, preferably about 0.5 ppm to about 1 ppm by weight. The dissolved H.sub.2 S is removed, by oxidation to sulfur, without the addition of polyvalent metal, e.g., iron, to the solution, and without blowdown of the condensate circulated through the cooling tower.

Claims12

Dependent claims

A process for removing H.sub.2 S from an aqueous condensate containing dissolved H.sub.2 S which comprises:

including with the condensate a chelated polyvalent metal catalyst in an amount sufficient to oxidize the dissolved H.sub.2 S to sulfur;
introducing the condensate containing the catalyst to a cooling tower from which it flows downwardly against an upward flow of air to cool and oxygenate the condensate and evaporate a portion of the condensate;
forming a recycle liquid in the cooling tower comprising cooled and oxygenated condensate;
collecting the recycle liquid in a water collection basin;
recycling the recycled liquid for reuse;
periodically removing and discarding from the process about 1% to about 10% of the recycle liquid after heat exchange with and condensation of a vaporized liquid containing H.sub.2 S, but before the recycle liquid is recycled to the cooling tower;
adding a chelated polyvalent metal to the condensate in an amount equal to the amount of recycle liquid removed and discarded from the process;
and
periodically or continuously adding a chelon, without polyvalent metal, to the condensate in an amount greater than the amount of polyvalent metal added to the condensate, and in an amount sufficient to maintain the polyvalent metal catalyst sufficiently active to oxidize the dissolved H.sub.2 S and provide, continuously, an amount of active polyvalent metal catalyst in the condensate of about 0.1 ppm to about 10 ppm by weight.

6 more elements

Dependencies are inferred from the claim text.