Integrated sulfur recovery and hydrogen production process
OwnerMahin Rameshni, Stephen L. Santoinventors
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Abstract
A process for producing hydrogen, sulfuric acid, and sulfur dioxide (SO2) utilizes the Sulfur-Iodine (S—I) thermochemical cycle. Acid gases, typically processed in sulfur recovery units, are combusted in an acid gas burner with air, enriched air, or oxygen, without fuel gas, to produce SO2. Iodine facilitates hydrogen production. A portion or all of the acid gases are directed to the burner in accordance with the present invention. The process reduces SO2 and CO2 emissions, with produced SO2 used for fertilizer production and CO2 sent for removal or CO2 liquefaction. The generated hydrogen supplies facility needs, such as hydrotreaters, reducing external imports and operating costs.
Claims20
A process for producing hydrogen, sulfur dioxide, and sulfuric acid from acid gas streams, comprising:
- (a) combusting an acid gas stream comprising hydrogen sulfide and ammonia, sourced from amine acid gas or sour water stripping, in an acid gas burner with an oxygen-containing gas and without fuel gas, to produce a combusted gas mixture comprising sulfur dioxide, carbon dioxide, nitrogen, water, oxygen, and sulfuric acid at a temperature of 900° C. to 2000° C.;
- (b) cooling the combusted gas mixture in a waste heat boiler to generate high-pressure steam or in a sulfuric acid vaporizer exchanger to recover heat and vaporize a portion of sulfuric acid;
- (c) further cooling and quenching the combusted gas mixture in a heat exchanger, wherein iodine, hydroiodic acid, and water are introduced to produce a reaction mixture;
- (d) reacting the reaction mixture in a reactor to produce hydrogen and iodine, and separating the hydrogen, water, and iodine in a three-phase separator, wherein the separated water is recycled and the hydrogen is collected as a product;
- (e) processing the cooled combusted gas mixture from step (c) by:
- (i) directing a first portion of the cooled combusted gas mixture to a secondary unit for sulfur dioxide liquefaction or production of other products;
- or (ii) reacting a second portion of the cooled combusted gas mixture with iodine and recycled water from step (d) in a second reactor at 100° C. to 200° C. to produce sulfuric acid and hydroiodic acid;
- (f) separating nitrogen and carbon dioxide from the reaction products of step (e)(ii) in a quench column, and directing a bottom stream comprising sulfuric acid, water, iodine, and hydroiodic acid to a liquid-liquid contactor to separate sulfuric acid from iodine and hydroiodic acid, wherein the iodine and hydroiodic acid are recycled to step (c);
- and (g) concentrating the separated sulfuric acid in a concentration unit using a steam reboiler to produce concentrated sulfuric acid as a product;
- wherein iodine is regenerated and reused as a catalyst, and the process reduces sulfur dioxide and carbon dioxide emissions by recovering carbon dioxide for further processing.
Dependencies are inferred from the claim text.