US4393031A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for efficiently removing oxides of nitrogen from exhaust gas
Assignee: Individual
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Filing: 1981-04-20
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Granted: 1983-07-12
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Expires: 2001-04-20
Abstract
Abstract A system for removal of oxides of nitrogen from the waste gas produced by various combustion processes discloses thoroughly mixing the waste gas with ammonia by means of a static mixing element and then passing the resultant mixture through a catalytic reactor. The ammonia may be supplied by reacting a portion of the waste gas with natural gas in the presence of a catalyst.
Inventors
- 👤 Werner Henke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:25
CPC Classifications
B; B01; B01F; B01F23/00; B01F23/10; B01F23/19; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/54; B01D53/56; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/206; F01N2240/00; F01N2240/25; F01N2610/00; F01N2610/02; F01N2610/11
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
138 words
A process for the removal of nitrogen oxides from a hot waste gas of a temperature of at least 420° F. and containing nitrogen oxides, comprising: dividing the waste gas into a first, second and third portion; passing said third portion through a cooling loop; adding a methane containing gas mixture to said second portion so as to convert part of said second portion into at least the amount of ammonia required for stoichiometric reaction with the nitrogen oxides in the waste gas; combining said first, third and ammonia containing second portion; thoroughly mixing said combination until said combination is substantially thermally and compositionally homogeneous by passing said combination through a static mixing element; and passing the thoroughly mixed combination over a catalyst that catalyzes the reduction of nitrogen oxides to gaseous nitrogen in the presence of ammonia.
Claim 2
Dependent Claim
138 words
A process for the removal of nitrogen oxides from a hot waste gas of a temperature of at least 420° F. and containing nitrogen oxides, comprising: dividing the waste gas into a first, second and third portion; passing said third portion through a cooling loop; adding a methane containing gas mixture to said second portion so as to convert part of said second portion into at least the amount of ammonia required for stoichiometric reaction with the nitrogen oxides in the waste gas; combining said first, third and ammonia containing second portion; thoroughly mixing said combination until said combination is substantially thermally and compositionally homogeneous by passing said combination through a static mixing element; and passing the thoroughly mixed combination over a catalyst that catalyzes the reduction of nitrogen oxides to gaseous nitrogen in the presence of ammonia.
Claim 3
Dependent Claim
176 words
A process for the removal of nitrogen oxides from a hot waste gas of a temperature of at least 420° F. and containing nitrogen oxides, comprising: dividing the waste gas into a first, second and third portion; passing said third portion through a cooling loop; re-combining said first and third portion; thoroughly mixing said re-combination until said recombination is thermally homogeneous by passing said re-combination through a first static mixing element; adding a methane containing gas mixture to said second portion so as to convert part of said second portion into at least the amount of ammonia required for stoichiometric reaction with the nitrogen oxides in the waste gas; combining said re-combined and thermally homogenized first and third portion with said ammonia containing second portion; thoroughly mixing said second combination until said second combination is substantially thermally and compositionally homogeneous by passing said second combination through a second static mixing element; and passing the thoroughly mixed second combination over a catalyst that catalyzes the reduction of nitrogen oxides to gaseous nitrogen in the presence of ammonia.
Claim 4
Dependent Claim
176 words
A process for the removal of nitrogen oxides from a hot waste gas of a temperature of at least 420° F. and containing nitrogen oxides, comprising: dividing the waste gas into a first, second and third portion; passing said third portion through a cooling loop; re-combining said first and third portion; thoroughly mixing said re-combination until said recombination is thermally homogeneous by passing said re-combination through a first static mixing element; adding a methane containing gas mixture to said second portion so as to convert part of said second portion into at least the amount of ammonia required for stoichiometric reaction with the nitrogen oxides in the waste gas; combining said re-combined and thermally homogenized first and third portion with said ammonia containing second portion; thoroughly mixing said second combination until said second combination is substantially thermally and compositionally homogeneous by passing said second combination through a second static mixing element; and passing the thoroughly mixed second combination over a catalyst that catalyzes the reduction of nitrogen oxides to gaseous nitrogen in the presence of ammonia.
Claim 5
Dependent Claim
29 words
The process recited in claim 1 or 2 wherein the catalyst is selected from the group consisting of a platinum group metal, vanadium oxide, molybdenum oxide, and tungsten oxide.
Claim 6
Dependent Claim
59 words
The process recited in claim 1 or 2 further comprising the step maintaining the temperature of the combination at between 420° F. and 520° F. during catalytic reduction of the nitrogen oxides by adjusting the bypass ratio of said third portion as against said first and second portions from between a maximum of less than 100% down to 0%.
Claim 7
Dependent Claim
38 words
The process of claim 4 further comprising the step of cooling said ammonia containing second portion prior to recombining it with said first and third portions in response to the temperature of the combination during the catalytic reduction.
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) | 1986-07-11 | 1987-01-10 | 1987-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-11 | 1991-01-10 | 1991-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-11 | 1995-01-10 | 1995-07-12 | $7700.00 | Window Closed / Lapsed |