US3764653A
Expired / Lapsed
US
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Continuous process for scrubbing so{11 {11 from a gas stream with h{11 {11 regeneration
Assignee: Universal Oil Products Co
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Filing: 1971-06-24
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Granted: 1973-10-09
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Expires: 1991-06-24
Abstract
Abstract An input gas stream containing SO2 is continuously treated in order to remove a substantial portion of the SO2 therefrom by the steps of: (a) scrubbing the input gas stream with an aqueous absorbent stream containing an alkaline reagent; (b) treating the resulting rich absorbent stream with a reducing agent at conditions selected to convert the sulfite compound contained therein to the corresponding thiosulfate compound; (c) catalytically reacting the resulting thiosulfate compound with hydrogen at reduction conditions selected to produce the corresponding sulfide compound; (d) stripping hydrogen sulfide from the resulting solution to form a regenerated aqueous absorbent stream; and, thereafter, (e) passing at least a portion of the regenerated absorbent stream to the scrubbing step. The principal utility of this scrubbing process is associated with the problem of continuously removing a sulfur dioxide contaminant from the flue or stack gas streams such as are typically produced in modern electrical power generating stations in order to abate a serious pollution problem and to enable the safe, nonpolluting burning of high sulfur fuels. Key features of this process are: the selective conversion of the sulfite compound obtained from the scrubbing step to the corresponding thiosulfate compound in the preliminary treatment step, the subsequent reduction of the thiosulfate compound to the corresponding sulfide compound in a highly efficient economic and selective manner, the minimization of undesired sulfate by-products during both of these conversion steps and the use of a relatively cheap, continuously regenerated absorbent which has a high capacity for SO2 as well as a high efficiency for SO2 removal.
Inventors
- 👤 P Urban
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 05:25
CPC Classifications
C; C01; C01B; C01B17/00; C01B17/22; C01B17/34; B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501; C01B17/02; C01B17/06; C01B17/16; C01B17/164
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
17 words
A process as defined in claim 1 wherein the alkaline reagent is ammonium carbonate or ammonium bicarbonate.
Claim 2
Dependent Claim
14 words
A process as defined in claim 1 wherein the alkaline reagent is ammonium hydroxide.
Claim 3
Dependent Claim
24 words
A process as defined in claim 1 wherein the alkaline reagent is an alkali metal hydroxide or alkali metal carbonate or alkali metal bicarbonate.
Claim 4
Dependent Claim
13 words
A process as defined in claim 4 wherein the alkali metal is sodium.
Claim 5
Dependent Claim
13 words
A process as defined in claim 4 wherein the alkali metal is potassium.
Claim 6
Dependent Claim
29 words
A process as defined in claim 1 wherein the alkaline reagent is water-soluble alkaline earth metal hydroxide or an alkaline earth metal carbonate or an alkaline earth metal bicarbonate.
Claim 7
Dependent Claim
43 words
A process as defined as in claim 1 wherein the thiosulfate production conditons utilized in step (b) include a temperature of about 20* to about 150* C. and a pressure sufficient to maintain the effluent stream from step (a) in the liquid phase.
Claim 8
Dependent Claim
41 words
A process as defined in claim 1 wherein the reduction conditions utilized in step (c) include a temperature of about 125* to about 350* C. and a pressure sufFicient to maintain the effluent stream from step (b) in the liquid phase.
Claim 9
Dependent Claim
33 words
A process as defined in claim 1 wherein the amount of hydrogen charged to step (c) is sufficient to provide a mole ratio of hydrogen to thiosulfate passed thereto of at least 4:1.
Claim 10
Dependent Claim
18 words
A process as defined in claim 1 wherein the reducing agent utilized in step (b) is hydrogen sulfide.
Claim 11
Dependent Claim
38 words
A process as defined in claim 11 wherein at least a portion of the hydrogen sulfide utilized in step (b) is obtained by passing to step (b) a portion of the H2S-containing overhead stream formed in step (d).
Claim 12
Dependent Claim
39 words
A process as defined in claim 1 wherein the reducing agent utilized in step (b) is finely divided sulfur which is used in an amount at least sufficient to provide a mole ratio of sulfur to sulfite of 1:1.
Claim 13
Dependent Claim
39 words
A process as defined in claim 1 wherein the reducing agent utilized in step (b) is a polysulfide compound which is used in an amount at least sufficient to provide a mole ratio of polysulfide to sulfite of 1:6.
Claim 14
Dependent Claim
44 words
A process as defined as in claim 1 wherein the reducing agent utilized in step (b) is a water-soluble sulfide compound which is used in an amount at least sufficient to provide a mole ratio of sulfide to sulfite in this step of 1:2.
Claim 15
Dependent Claim
80 words
A process as defined as in claim 1 wherein step (c) comprises contacting the effluent stream from step (b) and a hydrogen stream with a reduction catalyst, comprising a combination of a catalytically effective amount of a metallic component, selected from the group consisting of the transition metals and compounds of groups VI and VIII of the Periodic Table, with a porous carrier material, at reduction conditions selected to form a substantially thiosulfate-free aqueous effluent stream containing a sulfide compound.
Claim 16
Dependent Claim
27 words
A process as defined in claim 16 wherein the metallic component of the reduction catalyst is selected from the metal and compounds of the iron group metals.
Claim 17
Dependent Claim
15 words
A process as defined in claim 17 wherein the iron group metallic component is cobalt.
Claim 18
Dependent Claim
27 words
A process as defined in claim 18 wherein the reduction catalyst comprises a catalytically effective amount of cobalt sulfide combined with activated carbon or alumina carrier material.
Claim 19
Dependent Claim
197 words
A process for treating an input gas stream containing SO2 in order to continuously remove a substantial portion of the SO2 therefrom, said process comprising the steps of: a. contacting the input gas stream with an aqueous absorbent stream containing ammonium hydroxide or carbonate at scrubbing conditions selected to form a treated gas stream containing a reduced amount of SO2 and an effluent water stream containing ammonium sulfite or ammonium bisulfite; b. reacting at least a portion of the effluent water stream from step (a) with a reducing agent selected from the group consisting of finely divided sulfur, a polysulfide compound, a water-soluble sulfide compound and mixtures thereof, at thiosulfate production conditions selected to result in an effluent stream containing ammonium thiosulfate; c. catalytically treating the effluent stream from step (b) with hydrogen at reduction conditions selected to form a substantially thiosulfate-free aqueous effluent stream containing ammonium sulfide or hydrosulfide; d. stripping hydrogen sulfide from the aqueous effluent stream from step (c) to form an H2S-containing overhead gas stream and a regenerated aqueous absorbent stream containing ammonium hydroxide or carbonate; and thereafter, e. passing at least a portion of the resulting regenerated absorbent stream to step (a).
Claim 20
Dependent Claim
34 words
A process as defined in claim 20 wherein hydrogen is charged to step (c) in an amount corresponding to a mole ratio of hydrogen to thiosulfate passed thereto of about 4:1 to about 100:1.
Claim 21
Dependent Claim
18 words
A process as defined in claim 20 wherein the reducing agent utilized in step (b) is hydrogen sulfide.
Claim 22
Dependent Claim
38 words
A process as defined in claim 22 wherein at least a portion oF the hydrogen sulfide reactant utilized in step (b) is obtained by passing a portion of the overhead stream produced in step (d) to step (b).
Claim 23
Dependent Claim
56 words
A process as defined in claim 20 wherein step (c) comprises contacting the effluent stream from step (b) and a hydrogen stream with a catalyst, comprising a combination of a catalytically effective amount of cobalt sulfide with a porous carrier material, at reduction conditions selected to form a substantially thiosulfate-free aqueous effluent stream containing ammonium hydrosulfide.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |