US4048293A
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US
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Process for purifying a sulfur dioxide containing gas
Assignee: IFP Energies nouvelles
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Filing: 1976-03-29
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Granted: 1977-09-13
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Expires: 1996-03-29
Abstract
Abstract This process for purifying a sulfur dioxide containing gas, for example stack gas, comprises the steps of washing the gas with aqueous ammonia or ammonium sulfite, vaporizing sulfur dioxide and ammonia therefrom, reacting vaporized sulfur dioxide with hydrogen sulfide and recycling an ammonia containing stream. To avoid the drawbacks resulting from the presence of hydrogen sulfide in the recycle stream, a further oxidation step is provided to convert hydrogen sulfide to sulfur dioxide.
Inventors
- 👤 Philippe Renault
- 👤 Andre Deschamps
- 👤 Sigismond Franckowiak
- 👤 Claude Dezael
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:37
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501; B01D53/74; B01D53/86; B01D53/8603; B01D53/8612; C; C01; C01B; C01B17/00; C01B17/02; C01B17/04; C01B17/05
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
168 words
In a process for purifying a sulfur dioxide containing gas, which comprises the steps of (a) washing the gas with an aqueous solution of ammonia and/or ammonium sulfite and then separating the gas from the resulting aqueous solution of increased ammonium sulfites content, (b) heating the aqueous solution obtained in step (a) to decompose at least a portion of the sulfites and produce a stream of gas containing sulfur dioxide, ammonia and steam, (c) reacting hydrogen sulfide with the gas stream obtained in step (b), thereby producing elemental sulfur and a gas containing ammonia, steam and unconverted hydrogen sulfide, and separating the elemental sulfur from said gas, and (d) recycling to step (a) the ammonia obtained in step (c), the improvement which comprises subjecting the ammonia-containing gas separated in step (c) to controlled oxidation to selectively convert residual hydrogen sulfide to sulfur dioxide, and conducting step (d) by recycling ammonia and at least one member of the group consisting of sulfur dioxide and ammonium sulfite to step (a).
Claim 2
Dependent Claim
168 words
In a process for purifying a sulfur dioxide containing gas, which comprises the steps of (a) washing the gas with an aqueous solution of ammonia and/or ammonium sulfite and then separating the gas from the resulting aqueous solution of increased ammonium sulfites content, (b) heating the aqueous solution obtained in step (a) to decompose at least a portion of the sulfites and produce a stream of gas containing sulfur dioxide, ammonia and steam, (c) reacting hydrogen sulfide with the gas stream obtained in step (b), thereby producing elemental sulfur and a gas containing ammonia, steam and unconverted hydrogen sulfide, and separating the elemental sulfur from said gas, and (d) recycling to step (a) the ammonia obtained in step (c), the improvement which comprises subjecting the ammonia-containing gas separated in step (c) to controlled oxidation to selectively convert residual hydrogen sulfide to sulfur dioxide, and conducting step (d) by recycling ammonia and at least one member of the group consisting of sulfur dioxide and ammonium sulfite to step (a).
Claim 3
Dependent Claim
24 words
- A process according to claim 1, wherein the controlled oxidation is conducted at 400° - 650° C with a molecular oxygen containing gas.
Claim 4
Dependent Claim
43 words
- A process according to claim 1, wherein the controlled oxidation is conducted at 150° - 450° C with a molecular oxygen containing gas, in the presence of a catalyst comprising (a) a carrier and (b) at least one metal or metal oxide.
Claim 5
Dependent Claim
36 words
- A process according to claim 3, wherein the catalyst comprises (a) alumina, silica or alumina-silica and (b) a metal or metal oxide selected from the group comprising silver, silver oxide, vanadium oxide and iron oxide.
Claim 6
Dependent Claim
16 words
- A process according to claim 4, wherein the catalyst is vanadium oxide deposited on alumina.
Claim 7
Dependent Claim
28 words
- A process according to one of claim 1, wherein the molar ratio of H 2 S to SO 2 in step (c) is from 2/1 to 2.2/1.
Claim 8
Dependent Claim
28 words
- A process according to one of claim 1, wherein the molar ratio of H 2 S to SO 2 in step (c) is from 2.05/1 to 2.2/1.
Claim 9
Dependent Claim
36 words
- A process according to one of claim 1, wherein the molar ratio of H 2 S to NH 3 in the gas formed in step (c) and subjected to controlled oxidation is at most 0.5/1.
Claim 10
Dependent Claim
23 words
- A process according to claim 8, wherein the molar ratio of H 2 S to NH 3 is from 0.005/1 to 0.1/1.
Claim 11
Dependent Claim
25 words
- A process according to one of claim 1, wherein the molar ratio of 0 2 to H 2 S is from 1.5/1 to 6/1.
Claim 12
Dependent Claim
46 words
- A process according to one of claim 1, wherein the oxidation of the gas obtained in step (c) is carried out in a zone where a hydrocarbon is burnt, the molar proportion of free oxygen, not employed for the combustion, being from 1.5/1 to 6/1.
Claim 13
Dependent Claim
34 words
- A process according to one of claim 1, wherein step (a) is conducted at 0° - 100° C, step (b) at 100° - 180° C and step (c) at 100° - 200° C.
Claim 14
Dependent Claim
54 words
A process according to one of claim 1, wherein ammonium sulfate is present in the aqueous solution subjected to step (b), the residual aqueous phase from this step is delivered to a zone for converting ammonium sulfate to a gas containing sulfur dioxide and ammonia, and the latter gas is delivered to step (c).
Claim 15
Dependent Claim
36 words
A process according to claim 13, wherein the temperature of conversion of ammonium sulfate is 180° - 400° C, and this conversion is carried out by reduction with coal, coke, sulfur, hydrogen sulfide or ammonium thiosulfate.
Claim 16
Dependent Claim
29 words
- A process according to one of claim 1, wherein step (c) is conducted in a liquid which is inert with respect to hydrogen sulfide, sulfur dioxide and ammonia.
Claim 17
Dependent Claim
27 words
A process according to claim 1, wherein the gas separated in step (c) is subjected to controlled oxidation and recycled in the gaseous state to step (a).
Claim 18
Dependent Claim
49 words
A process according to claim 1, wherein the gas separated in step (c) is cooled to obtain an aqueous solution of ammonia and ammonium sulfite and a residual gas; said residual gas is discharged; and said aqueous solution of ammonia and ammonium sulfite is fed back to step (a).
References Cited (Backward Citations)
US2083894A
Cited
US3882222A
Cited
US3839549A
Cited
US3883638A
Cited
US3875295A
Cited
US3896215A
Cited
US3895101A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-12 | 1981-03-14 | 1981-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-12 | 1985-03-14 | 1985-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-12 | 1989-03-14 | 1989-09-13 | $7700.00 | Window Closed / Lapsed |