Hydrogen generation process with dual pressure multi stage electrolysis
View Patent ↗A multi-pressure hybrid sulfur process ( 2 ) contains at least one electrolyzer unit ( 16 ) which provides liquid H 2 SO 4 to a preheater/vaporizer reactor ( 20 ) operating at a pressure of from 1 MPa to 9 MPa to form gaseous H 2 SO 4 which is passed to a decomposition reactor ( 14 ) operating at a pressure of from 7 MPa to 9 MPa, where decomposed H 2 SO 4 is passed to at least one scrubber unit ( 14 ) and at least one electrolyzer unit ( 16 ) both preferably operating at a pressure of 0.1 MPa to 7 MPa, where an associated Rankine Cycle power conversion unit ( 50 ) supplies electricity.
1. A dual pressure hybrid sulfur process for hydrogen generation, utilizing the decomposition of H 2 SO 4 to H 2 O, SO 2 and O 2 with heat from a nuclear reactor or natural gas fired combustor, which comprises:
(a) utilizing a sulfur cycle, selected from the group consisting of a Westinghouse Sulfur Process and a Sulfur Iodine Process, wherein an electrolyzer provides H 2 SO 4 liquid to a H 2 SO 4 vaporizer reactor operating at a pressure and a temperature effective to provide vaporized gaseous H 2 SO 4 ; which gaseous H 2 SO 4 is decomposed to gaseous H 2 O, SO 2 and O 2 in a decomposition reactor operating at a pressure of from 7 MPa to 9 MPa;
(b) passing the H 2 O, SO 2 and O 2 gases to a plurality of SO 2 scrubber units to remove O 2 streams, operating with a plurality of electrolyzer units;
(c) inputting electricity to the plurality of electrolyzer units to produce hydrogen gas and H 2 SO 4 liquid, where both the plurality of SO 2 scrubber units and the plurality of electrolyzer units operate at a pressure of 0.1 MPa to 7 MPa;
(d) supplying electricity to the plurality of electrolyzer units utilizing a Rankine Cycle Power Conversion Unit; and
(e) supplying fluid heat to the Rankine Cycle Unit and the sulfur cycle, utilizing a heat source selected from the group consisting of a nuclear reactor and a natural gas fired combustor;
where the decomposition reactor operates at a pressure higher than the scrubber and electrolyzer units, providing a dual pressure hybrid process.
2. The hybrid sulfur process of claim 1 , wherein a combination heat exchanger and H 2 SO 4 vaporizer are used to preheat the inlet liquid sulfuric liquid and concentrate it to between 80% and 95% H 2 SO 4 , and feed the hot concentrated H 2 SO 4 to the decomposition reactor.
3. The hybrid sulfur process of claim 2 , wherein the H 2 SO 4 vaporizer reactor is located above the decomposition reactor, allowing gravity flow of concentrated/gaseous H 2 SO 4 to eliminate the need for a pump to supply the decomposition reactor.
4. The hybrid sulfur process of claim 1 , wherein the plurality of SO 2 scrubber units and electrolyzer units reduces SO 2 loss to the O 2 streams.
5. The hybrid sulfur process of claim 4 , wherein SO 2 is absorbed and electrolyzed to H 2 SO 4 in several stages, so that the sulfuric acid leaving each electrolyzer unit is depleted in SO 2 allowing acid to be efficiently used in the scrubbing liquid for the next absorption stage.
6. The hybrid sulfur process of claim 1 , wherein the Rankine Cycle is steam based and passes cooled fluid heat back to the heat source.
7. The hybrid sulfur process of claim 1 , wherein the decomposition reactor is operated at about 750° C.-760° C., to increase the efficiency of the associated Rankine Cycle.
8. The hybrid sulfur process of claim 1 , wherein the heat source is a nuclear reactor and the sulfur cycle is a Westinghouse Sulfur Process.
9. The hybrid sulfur process of claim 8 , wherein fluid heat from the nuclear reactor is first passed to a heat exchanger then to the Rankine cycle.