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US3873672A
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Desulfurization of gases containing sulfur compounds using alkaline hypochlorite solutions
Assignee: Daiki Engineering Co Ltd
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Filing: 1973-02-07
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Granted: 1975-03-25
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Expires: 1993-02-07
Abstract
Abstract Gases containing sulfur compounds, especially sulfur dioxide are contacted with a scrubbing solution comprising alkali hypochlorite, which is formed by the electrolysis of alkali chloride, and hydroxide of alkali or alkali-earth metals. Sulfur dioxide in the gases is oxidized by alkali hypochlorite in the presence of alkali or alkali-earth hydroxide, and alkali or alkali-earth sulfate and alkali chloride are formed. The scrubbed gases are free of sulfur compounds. The electrolysis of alkali chloride is preferably carried out under a pH between about 8.5 and about 10. The scrubbing solution should have a pH higher than 8.5. In case that sodium oxide is used as an alkali hydroxide, sodium sulfate is formed and separated from the solution by suitable methods such as deep cooling to crystalize it out as Glauber''s salt which is recovered by subsequent filtration. Remaining solution containing mainly sodium chloride is recycled for further electrolysis to reproduce the sodium hypochlorite for the scrubbing solution. Calcium hydroxide can be used in a similar manner as a hydroxide, producing calcium sulfate (gypsum) as the end product. In this case the electrolysis is preferably carried out under a pH between 7.5 to 9.
Inventors
- 👤 Yoshiharu Nishiba
- 👤 Kazuhiko Ota
- 👤 Hideya Inaba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:03
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
96 words
A PROCESS FOR THE DESULFURIZATION OF GASES CONTAINING SULFUR COMPOUNDS, WHICH COMPRISES CONTACTING A HOT GAS CONTAINING SULFUR COMPOUNDS WITH A SCRUBBING SOLUTION HAVING A PH GREATER THAN 8.5 AND CONTAINING SODIUM HYPOCHLORITE AND CALCIUM HYDROXIDE IN A SCRUBBER, THE SODIUM HYPOCHLORITE BEING PRODUCED BY THE ELECTROLYSIS OF SODIUM CHLORIDE SOLUTION, REACTING SAID SULFUR COMPOUNDS WITH SAID SCRUBBING SOLUTION IN SAID SCRUBBER TO FORM CALCIUM SULFATE AND SODIUM CHLORIDE, FILTERING CALCIUM SULFATE AS CRYSTALS FROM THE EFFLUENT SOLUTION FROM SAID SCRUBBER, AND RECYCLING THE REMAINING SOLUTION FROM SAID FILTRATION FOR FURTHER ELECTROLYSIS TO PRODUCE SODIUM HYPOCHLORITE.
Claim 2
Dependent Claim
96 words
A PROCESS FOR THE DESULFURIZATION OF GASES CONTAINING SULFUR COMPOUNDS, WHICH COMPRISES CONTACTING A HOT GAS CONTAINING SULFUR COMPOUNDS WITH A SCRUBBING SOLUTION HAVING A PH GREATER THAN 8.5 AND CONTAINING SODIUM HYPOCHLORITE AND CALCIUM HYDROXIDE IN A SCRUBBER, THE SODIUM HYPOCHLORITE BEING PRODUCED BY THE ELECTROLYSIS OF SODIUM CHLORIDE SOLUTION, REACTING SAID SULFUR COMPOUNDS WITH SAID SCRUBBING SOLUTION IN SAID SCRUBBER TO FORM CALCIUM SULFATE AND SODIUM CHLORIDE, FILTERING CALCIUM SULFATE AS CRYSTALS FROM THE EFFLUENT SOLUTION FROM SAID SCRUBBER, AND RECYCLING THE REMAINING SOLUTION FROM SAID FILTRATION FOR FURTHER ELECTROLYSIS TO PRODUCE SODIUM HYPOCHLORITE.
Claim 3
Dependent Claim
32 words
A process of claim 1, wherein the electrolysis of the solution containing sodium chloride for the production of sodium hypochlorite is carried out under a pH adjusted between about 7.5 to 9.
Claim 4
Dependent Claim
28 words
A process of claim 1, wherein at least a portion of the remaining solution is concentrated by evaporation of water before it is recycled to the electrolysis cell.
Claim 5
Dependent Claim
172 words
A process for desulfurization of hot gases containing sulfur compounds, which comprises contacting a hot gas containing sulfur compounds with a scrubbing solution having a pH higher than 8.5 and containing sodium hypochlorite and sodium hydroxide in a series of multistage scrubbers, the sodium hypochlorite being produced by the electrolysis of sodium chloride solution, reacting the sulfur compounds with said scrubbing solution in said scrubbers to form sodium sulfate, separating the sodium sulfate thus formed from the effluent solution from the last stage scrubber as crystals of sodium sulfate decahydrate by deep cooling the effluent solution and subsequent filtration, converting the separated crystals of sodium sulfate decahydrate into a saturated solution of sodium sulfate by fusion, rEcycling the sodium sulfate solution thus formed to the first stage scrubber thereby to form sodium sulfate in a dehydrated form while cooling the hot gas in the scrubber, and recovering said dehydrate sodium sulfate from said first-stage scrubber, and recycling the solution remaining after the sodium sulfate separation for further electrolysis to produce sodium hypochlorite.
Claim 6
Dependent Claim
172 words
A process for desulfurization of hot gases containing sulfur compounds, which comprises contacting a hot gas containing sulfur compounds with a scrubbing solution having a pH higher than 8.5 and containing sodium hypochlorite and sodium hydroxide in a series of multistage scrubbers, the sodium hypochlorite being produced by the electrolysis of sodium chloride solution, reacting the sulfur compounds with said scrubbing solution in said scrubbers to form sodium sulfate, separating the sodium sulfate thus formed from the effluent solution from the last stage scrubber as crystals of sodium sulfate decahydrate by deep cooling the effluent solution and subsequent filtration, converting the separated crystals of sodium sulfate decahydrate into a saturated solution of sodium sulfate by fusion, rEcycling the sodium sulfate solution thus formed to the first stage scrubber thereby to form sodium sulfate in a dehydrated form while cooling the hot gas in the scrubber, and recovering said dehydrate sodium sulfate from said first-stage scrubber, and recycling the solution remaining after the sodium sulfate separation for further electrolysis to produce sodium hypochlorite.
Claim 7
Dependent Claim
32 words
A process of claim 4, wherein the electrolysis of the solution containing sodium chloride for the production of sodium hypochlorite is carried out under a pH adjusted between about 8.5 to 10.
Claim 8
Dependent Claim
28 words
A process of claim 4, wherein at least a portion of the remaining solution is concentrated by evaporation of water before it is recycled to the electrolysis cell.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |