Control of thiosulfate in wet desulfurization process solutions
AssigneeFMC Corporation
InventorHarry M. Castrantas
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Abstract
A method for controlling the concentration of dissolved thiosulfate byproduct which forms in a wet desulfurization process, by introducing a peroxygen chemical into its recirculating aqueous absorption medium. A peroxygen chemical such as aqueous hydrogen peroxide is introduced into the recirculating aqueous alkaline absorption medium, preferably after its regeneration, in an amount sufficient to maintain the concentration of thiosulfate byproduct below a saturation concentration. The method is applicable to cyclic wet desulfurization processes, used to recover elemental sulfur from H.sub.2 S-containing gas streams, in which the absorption medium contains a regenerable oxidizing agent and is subject to thiosulfate byproduct buildup.
Claims20
In a cyclic wet desulfurization process for recovering elemental sulfur from hydrogen sulfide-containing gas streams by the steps of
- (i) contacting an H.sub.2 S-containing gas stream with an aqueous alkaline absorption medium containing a regenerable oxidizing agent;
- (ii) absorbing H.sub.2 S into the absorption medium and converting it to a hydrosulfide;
- (iii) oxidizing the hydrosulfide with the oxidizing agent to form sulfur, which is subsequently recovered from the absorption medium;
- (iv) regenerating the absorption medium by contacting it with an oxygen-containing gas;
- and
- (v) recirculating the regenerated absorption medium to repeat the desulfurization cycle;
- the improvement for controlling the concentration of dissolved thiosulfate byproduct which forms in the absorption medium, which comprises introducing a peroxide chemical, selected from the group consisting of hydrogen peroxide, sodium carbonate peroxide, and sodium peroxide, into the thiosulfate-containing absorption medium in an amount sufficient to maintain the thiosulfate below its saturation concentration.
In a cyclic wet desulfurization process for recovering elemental sulfur from hydrogen sulfide-containing gas streams by the steps of
- (i) contacting an H.sub.2 S-containing gas stream with an aqueous alkaline absorption medium containing an anthraquinone disulfonic acid salt and an alkali metal vanadate;
- (ii) absorbing H.sub.2 S from the gas stream into the absorption medium, and thereby forming a dissolved hydrosulfide;
- (iii) providing sufficient time for the dissolved hydrosulfide to be oxidized to elemental sulfur, in the presence of the anthraquinone disulfonic acid salt and alkali metal vanadate;
- (iv) regenerating the absorption medium by contacting it with an oxygen-containing gas;
- (v) recovering the elemental sulfur from the absorption medium;
- and
- (vi) recirculating the regenerated absorption medium to repeat the desulfurization cycle;
- the improvement for controlling the concentration of dissolved thiosulfate byproduct which forms in the absorption medium, which comprises introducing aqueous hydrogen peroxide into the thiosulfate-containing absorption medium, after regeneration of the absorption medium, in an amount sufficient to maintain the thiosulfate below its saturation concentration.
Dependencies are inferred from the claim text.