US4038368A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for removing oxides of nitrogen and sulfur from exhaust gases
Assignee: Mitsubishi Heavy Industries Ltd
•
Filing: 1975-05-20
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Granted: 1977-07-26
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Expires: 1995-05-20
Abstract
Abstract A process for wet-treating an exhaust gas to remove oxides of sulfur and of nitrogen including: 1. washing the exhaust gas with a slurry containing one or more magnesium compounds to remove oxides of sulfur from the exhaust gas; 2. washing the exhaust gas treated in step (1) with an aqueous solution of an alkali metal iodide and/or an alkaline earth metal iodide to remove the oxide of nitrogen; and 3. contacting the slurry from step (1) with the aqueous solution from step (2) to regenerate the solution of alkali metal iodide and/or alkaline earth metal iodide and to decompose any nitrite formed in step (2) to nitrogen.
Inventors
- 👤 Masumi Atsukawa
- 👤 Naoharu Shinoda
- 👤 Naohiko Ukawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:51
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/60; Y; Y02; Y02A; Y02A50/00; Y02A50/20
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
134 words
A process for wet-treating an exhaust gas to remove an oxide or sulfur and nitrogen dioxide from the exhaust gas, which process comprises the steps of: 1. washing the exhaust gas with a slurry containing one or more magnesium compounds which will react with oxides of sulfur, thereby removing the oxide of sulfur from the exhaust gas; 2. washing the exhaust gas treated in step (1) with an aqueous solution of an alkali metal iodide, an alkaline earth metal iodide or mixtures thereof to remove the oxide of nitrogen from the exhaust gas; and 3. contacting the slurry from step (1) with the aqueous solution from step (2) to regenerate the solution of alkali metal iodide, alkaline earth metal iodide or mixtures thereof and to decompose any nitrite formed in step (2) to nitrogen.
Claim 2
Dependent Claim
134 words
A process for wet-treating an exhaust gas to remove an oxide or sulfur and nitrogen dioxide from the exhaust gas, which process comprises the steps of: 1. washing the exhaust gas with a slurry containing one or more magnesium compounds which will react with oxides of sulfur, thereby removing the oxide of sulfur from the exhaust gas; 2. washing the exhaust gas treated in step (1) with an aqueous solution of an alkali metal iodide, an alkaline earth metal iodide or mixtures thereof to remove the oxide of nitrogen from the exhaust gas; and 3. contacting the slurry from step (1) with the aqueous solution from step (2) to regenerate the solution of alkali metal iodide, alkaline earth metal iodide or mixtures thereof and to decompose any nitrite formed in step (2) to nitrogen.
Claim 3
Dependent Claim
33 words
A process according to claim 1 wherein the exhaust gas from step (1) is treated with an oxidizing agent to convert any nitric oxide to nitrogen dioxide before being subjected to step (2).
Claim 4
Dependent Claim
17 words
A process according to claim 2 wherein the oxidizing agent is ozone, hydrogen peroxide, or nitric acid.
Claim 5
Dependent Claim
48 words
A process according to claim 1 wherein step (1) is carried out in two stages, the exhaust gas passing through a first stage and then through a second stage while the slurry is supplied first to the second stage and then to the first stage of step (1).
Claim 6
Dependent Claim
42 words
A process according to claim 1 wherein the slurry from step (3) is separated into a solid phase and a liquid phase containing alkali metal iodide, alkaline earth metal iodide or mixtures thereof and the liquid phase is recycled into step (2).
Claim 7
Dependent Claim
30 words
A process according to claim 5 wherein the slurry from the third step is reacted with magnesium hydroxide to convert magnesium bisulfite to magnesium sulfite hexahydrate prior to the separation.
Claim 8
Dependent Claim
37 words
A process according to claim 6 wherein the separated magnesium sulfite hexahydrate is roasted to convert it to magnesium oxide which upon admixture with water forms the slurry for step (1) and is recycled into step (1).
Claim 9
Dependent Claim
90 words
A process for wet-treating an exhaust gas to remove an oxide of sulfur and an oxide of nitrogen from the exhaust gas, which process comprises the steps of: washing the exhaust gas with a mixture of (a) a slurry containing one or more magnesium compounds which will react with oxides of sulfur, (b) an aqueous solution of an aqueous solution of an alkali metal iodide, an alkaline earth metal iodide or mixtures thereof to remove the oxide of nitrogen from the exhaust gas, and to decompose any nitrite to nitrogen.
Claim 10
Dependent Claim
90 words
A process for wet-treating an exhaust gas to remove an oxide of sulfur and an oxide of nitrogen from the exhaust gas, which process comprises the steps of: washing the exhaust gas with a mixture of (a) a slurry containing one or more magnesium compounds which will react with oxides of sulfur, (b) an aqueous solution of an aqueous solution of an alkali metal iodide, an alkaline earth metal iodide or mixtures thereof to remove the oxide of nitrogen from the exhaust gas, and to decompose any nitrite to nitrogen.
Claim 11
Dependent Claim
39 words
A process according to claim 1 which includes the additional step of admixing the slurry from step (1) with the aqueous solution used in step (2) so that step (3) of the process is carried out with step (2).
References Cited (Backward Citations)
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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) | 1980-07-25 | 1981-01-24 | 1981-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-25 | 1985-01-24 | 1985-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-25 | 1989-01-24 | 1989-07-26 | $7700.00 | Window Closed / Lapsed |