US3843771A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for suppressing sulfate make in a so scrubbing step
Assignee: Universal Oil Products Co
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Filing: 1972-02-14
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Granted: 1974-10-22
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Expires: 1992-02-14
Abstract
Abstract A process for the removal of SO2 from a gas stream containing SO2 and O2 wherein the use of a conventional scrubbing solution containing an alkaline reagent results in the formation of an undesired, intractable sulfate by-product, is improved by adding to the scrubbing zone a reducing agent, selected from the group consisting of finely divided sulfur, a polysulfide compound, a water-soluble sulfide compound and mixtures thereof in an amount corresponding to about 5 to about 95% of the stoichiometric amount of reducing agent necessary to convert all of the absorbed SO2 into thiosulfate, and by thereafter operating the scrubbing zone under thiosulfate production conditions. Principal utility of this improved process is associated with the process for scrubbing SO2 from the flue or stack gas stream containing oxygen wherein it is desired to minimize sulfate by-produts and prevent the contamination of the treated gas stream. Key feature of this improved process involves the selective conversion of a portion of the absorbed SO2 to the corresponding thiosulfate compound within the scrubbing zone thereby minimizing the opportunity for the oxygen contained in the input gas stream to oxidize the freshly absorbed SO2 to the undesired sulfate by-product.
Inventors
- 👤 P Urban
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:53
CPC Classifications
C; C01; C01B; C01B17/00; C01B17/64; B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501; B01D53/507; C01B17/02; C01B17/06; C01B17/16; C01B17/164
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
241 words
IN A PROCESS FOR THE REMOVAL OF SO2 FROM AN INPUT GAS STREAM CONTAINING SO2 AND O2, WHEREIN THE INPUT GAS STREAM IS CONTACTED, IN A GAS-LIQUID SCRUBBING ZONE, WITH AN AQUEOUS SCRUBBING SOLUTION CONTAINING AN ALKALINE REAGENT AT SCRUBBING CONDITIONS SELECTED TO FORM A TREATED GAS STREAM CONTAINING SUBSTANTIALLY LESS SO2 THAN THE IMPUT GAS STREAM AND A RICH SCRUBBING SOLUTION CONTAINING A WATER-SOLUBLE SULFITE COMPOUND AND WHEREIN AT LEAST A PORTION OF THE OXYGEN PRESENT IN THE INPUT GAS STREAM REACTS WITH A PORTION OF THE RESULTING SULFITE COMPOUND TO FORM AN UNDESIRED, INTRACTABLE SULFATE BY PRODUCT, THE IMPROVEMENT COMPRISING: ADDING TO THE SCRUBBING ZONE A REDUCING AGENT, SELECTED FROM THE GROUP CONSISTING OF FINELY DIVIDED SULFUR A POLYSULFIDE COMPOUND, WATER-SOLUBLE SULFIDE COMPOUND AND MIXTURE THEREOF, SAID FINELY DIVIDED SULFUR BEING ADDED IN AN AMOUNT OF FROM ABOUT .05 TO ABOUT 0.95 ATOMS OF SULFUR PER MOLECULE OF ABSORBED SO2, SAID POLYSULFIDE COMPOUND BEING ADDED IN AN AMOUNT OF ABOUT .05 TO ABOUT .95 MOLES OF POLYSULFIDE PER 6 MOLES OF ABSORBED SO2, AND SAID WATER-SOLUBLE SULFIDE BEING ADDED IN AN AMOUNT OF FROM ABOUT .025 TO ABOUT 0.495 MOLES OF SULFIDE PER MOLE OF ABSORBED SO2 AND THEREAFTER, OPERATING THE SCRUBBING ZONE UNDER THIOSULFATE PRODUCTION CONDITIONS SELECTED TO REACT THE REDUCING AGENT WITH A PORTION OF THE WATER-SOLUBLE SULFITE COMPOUND AS IT IS FORMED TO PRODUCE THE CORRESPONDING THIOSULFATE COMPOUND, THEREBY SUPRESSING THE PRODUCTION OF UNDESIRED SULFATE BY-PRODUCTS.
Claim 2
Dependent Claim
241 words
IN A PROCESS FOR THE REMOVAL OF SO2 FROM AN INPUT GAS STREAM CONTAINING SO2 AND O2, WHEREIN THE INPUT GAS STREAM IS CONTACTED, IN A GAS-LIQUID SCRUBBING ZONE, WITH AN AQUEOUS SCRUBBING SOLUTION CONTAINING AN ALKALINE REAGENT AT SCRUBBING CONDITIONS SELECTED TO FORM A TREATED GAS STREAM CONTAINING SUBSTANTIALLY LESS SO2 THAN THE IMPUT GAS STREAM AND A RICH SCRUBBING SOLUTION CONTAINING A WATER-SOLUBLE SULFITE COMPOUND AND WHEREIN AT LEAST A PORTION OF THE OXYGEN PRESENT IN THE INPUT GAS STREAM REACTS WITH A PORTION OF THE RESULTING SULFITE COMPOUND TO FORM AN UNDESIRED, INTRACTABLE SULFATE BY PRODUCT, THE IMPROVEMENT COMPRISING: ADDING TO THE SCRUBBING ZONE A REDUCING AGENT, SELECTED FROM THE GROUP CONSISTING OF FINELY DIVIDED SULFUR A POLYSULFIDE COMPOUND, WATER-SOLUBLE SULFIDE COMPOUND AND MIXTURE THEREOF, SAID FINELY DIVIDED SULFUR BEING ADDED IN AN AMOUNT OF FROM ABOUT .05 TO ABOUT 0.95 ATOMS OF SULFUR PER MOLECULE OF ABSORBED SO2, SAID POLYSULFIDE COMPOUND BEING ADDED IN AN AMOUNT OF ABOUT .05 TO ABOUT .95 MOLES OF POLYSULFIDE PER 6 MOLES OF ABSORBED SO2, AND SAID WATER-SOLUBLE SULFIDE BEING ADDED IN AN AMOUNT OF FROM ABOUT .025 TO ABOUT 0.495 MOLES OF SULFIDE PER MOLE OF ABSORBED SO2 AND THEREAFTER, OPERATING THE SCRUBBING ZONE UNDER THIOSULFATE PRODUCTION CONDITIONS SELECTED TO REACT THE REDUCING AGENT WITH A PORTION OF THE WATER-SOLUBLE SULFITE COMPOUND AS IT IS FORMED TO PRODUCE THE CORRESPONDING THIOSULFATE COMPOUND, THEREBY SUPRESSING THE PRODUCTION OF UNDESIRED SULFATE BY-PRODUCTS.
Claim 3
Dependent Claim
22 words
An improved process as defined in claim 1 wherein the alkaline reagent contained in the scrubbing solution is ammonium carbonate or bicarbonate.
Claim 4
Dependent Claim
21 words
An improved process as defined as in claim 1 wherein the alkaline reagent contained in the scrubbing solution is ammonium hydroxide.
Claim 5
Dependent Claim
27 words
An improved process as defined as in claim 1 wherein the alkaline reagent contained in the scrubbing solution is an alkali metal hydroxide or carbonate or bicarbonate.
Claim 6
Dependent Claim
14 words
An improved process as defined in claim 4 wherein the alkali metal is sodium.
Claim 7
Dependent Claim
15 words
An improved process as defined as in claim 4 wherein the alkali metal is potassium.
Claim 8
Dependent Claim
27 words
An improved process as defined as in claim 1 wherein the alkaline reagent contained in the scrubbing solution is an alkaline earth metal hydroxide, carbonate or bicarbonate.
Claim 9
Dependent Claim
16 words
An improved process as defined as in claim 7 wherein the alkaline earth metal is calcium.
Claim 10
Dependent Claim
15 words
An improved process as defined in claim 7 wherein the alkaline earth metal is magnesium.
Claim 11
Dependent Claim
40 words
An improved process as defined in claim 1 wherein the thiosulfate production conditions include a temperature of about 5 to about 100*C., a pressure sufficient to maintain the scrubbing solution in the liquid phase and a pH less than 7.
Claim 12
Dependent Claim
17 words
An improved process as defined as in claim 1 wherein the reducing agent is finely divided sulfur.
Claim 13
Dependent Claim
20 words
An improved process as defined as in claim 11 wherein a wetting agent is also added to the contacting zone.
Claim 14
Dependent Claim
18 words
An improved process as defined as in claim 12 wherein the wetting agent is a quaternary ammonium salt.
Claim 15
Dependent Claim
17 words
An improved process as defined as in claim 1 wherein the reducing agent is a polysulfide compound.
Claim 16
Dependent Claim
17 words
An improved process as defined in claim 14 wherein the polysulfide compound is sodium or ammonium polysulfide.
Claim 17
Dependent Claim
18 words
An improved process as defined as in claim 1 wherein the reducing agent is a water-soluble sulfide compound.
Claim 18
Dependent Claim
17 words
An improved process as defined as in claim 16 wherein the water-soluble sulfide compound is hydrogen sulfide.
Claim 19
Dependent Claim
17 words
An improved process as defined as in claim 16 wherein the water-soluble sulfide compound is ammonium hydrosulfide.
Claim 20
Dependent Claim
17 words
An improved process as defined as in claim 16 wherein the water-soluble sulfide compound is sodium sulfide.
Claim 21
Dependent Claim
81 words
An improved process as defined as in claim 1 wherein said finely divided sulfur is added in an amount of from about .3 to about 0.7 atoms of sulfur per molecule of absorbed SO2, said polysulfide compound is added in an amount of about .3 to about .7 moles of polysulfide per 6 moles of absorbed SO2, and said water-soluble sulfide is added in an amount of from about .15 to about 0.35 moles of sulfide per mole of absorbed SO2.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |