US4267155A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for cleaning flue gas
Assignee: Mitsubishi Kakoki Kaisha Ltd
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Filing: 1979-08-20
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Granted: 1981-05-12
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Expires: 1999-08-20
Abstract
Abstract A flue gas containing SO x , NO x and O 2 is washed with an alkaline aqueous solution containing a NO x removal catalyst to form the salts of a dithionate, a sulfate and an imidobissulfate. The salts are crystallized, separated and heated for pyrolysis by a pneumatic conveying pyrolysis unit whereby a gas containing higher concentration of SO 2 is obtained. The gas is fed into the alkaline aqueous solution together with the flue gas so as to improve the efficiency.
Inventors
- 👤 Yoshio Kobayashi
- 👤 Koichi Ando
- 👤 Susumu Hyodo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:16
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/60; Y; Y02; Y02A; Y02A50/00; Y02A50/20
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
121 words
In a process for cleaning a flue gas containing SO x , NO x and O 2 by washing with an alkaline aqueous solution containing a NO x removal catalyst, wherein a dithionate, a sulfate and an imidobissulfate, formed in said washing step are separated as their crystals, the improvement comprising heating the crystals to a temperature higher than the pyrolysis temperature of the dithionate but lower than the pyrolysis temperatures of the imidobissulfate to form a solid product and a gas containing SO 2 , separating the gas containing SO 2 and feeding it into said alkaline aqueous solution for washing the flue gas whereby the SO 2 gas produced by the pyrolysis is effectively utilized for NO x removal.
Claim 2
Dependent Claim
121 words
In a process for cleaning a flue gas containing SO x , NO x and O 2 by washing with an alkaline aqueous solution containing a NO x removal catalyst, wherein a dithionate, a sulfate and an imidobissulfate, formed in said washing step are separated as their crystals, the improvement comprising heating the crystals to a temperature higher than the pyrolysis temperature of the dithionate but lower than the pyrolysis temperatures of the imidobissulfate to form a solid product and a gas containing SO 2 , separating the gas containing SO 2 and feeding it into said alkaline aqueous solution for washing the flue gas whereby the SO 2 gas produced by the pyrolysis is effectively utilized for NO x removal.
Claim 3
Dependent Claim
50 words
A process for cleaning a flue gas according to claim 1 wherein said solid product separated after pyrolysis is converted into a base by a reducing treatment with heating at high temperature in a reducing atmosphere and carbonating treatment and said base is used for preparing said alkaline aqueous solution.
Claim 4
Dependent Claim
26 words
A process for cleaning a flue gas according to claims 1 or 2, wherein said pyrolysis step is carried out in a pneumatic conveying pyrolysis unit.
Claim 5
Dependent Claim
41 words
A process for cleaning a flue gas according to claim 3 wherein the pneumatic conveying pyrolysis unit comprises a pyrolysis tube through which said crystals and a hot gas are concurrently passed at a resident time of 0.05 to 10 seconds.
Claim 6
Dependent Claim
52 words
A process for cleaning a flue gas according to claim 3 wherein the pneumatic conveying pyrolysis unit comprises a pyrolysis tube which is heated by a hot gas fed concurrently together with said crystals so as to heat said crystals to 370° to 380° C. at the outlet of said pyrolysis tube.
References Cited (Backward Citations)
US4044101A
Cited
US4186176A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-05-11 | 1984-11-10 | 1985-05-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-05-11 | 1988-11-10 | 1989-05-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-05-11 | 1992-11-10 | 1993-05-12 | $7700.00 | Window Closed / Lapsed |