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US5131335A
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Process for reducing nitric oxide emission during the combustion of solid fuels
Assignee: Saarbergwerke AG
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Filing: 1990-12-21
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Granted: 1992-07-21
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Expires: 2010-12-21
Abstract
Abstract In a process for reducing the nitric oxide emission during the combustion of solid fuels, the flue gases leaving from a main combustion zone (2) consecutively flow through two reduction zones (6,9). The first reduction zone (6) is operated hypostoichiometrically at temperatures above 1,000° C. and while adding a reducing fuel, while the second reduction zone (9) is operated hyperstoichiometrically at temperatures from 950° C. to 1,000° C. and in the presence of nitric oxide-reducing substances.
Inventors
- 👤 Heinz Spliethoff
- 👤 Hartmut Spliethoff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:18
CPC Classifications
F; F23; F23C; F23C6/00; F23C6/04; F23C6/045; F23C6/047; F23J; F23J7/00; F23C2201/00; F23C2201/10; F23C2201/101; F23C2201/30; F23C2201/301
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
90 words
Process for the reduction of nitric oxide emission during the combustion of solid fuels, particularly hard coals, whereby a reducing fuel is added to the flue gases leaving a main combustion zone and is burned, characterized in that the flue gases pass consecutively through two reaction zones; that the first reaction zone is operated hypostoichiometrically at temperatures above 1,000° C. and while adding a reducing fuel; and that the second reduction zone is operated hyperstoichiometrically in the presence of nitric oxide-reducing substances at temperatures from 950° C. to 1,000° C.
Claim 2
Dependent Claim
90 words
Process for the reduction of nitric oxide emission during the combustion of solid fuels, particularly hard coals, whereby a reducing fuel is added to the flue gases leaving a main combustion zone and is burned, characterized in that the flue gases pass consecutively through two reaction zones; that the first reaction zone is operated hypostoichiometrically at temperatures above 1,000° C. and while adding a reducing fuel; and that the second reduction zone is operated hyperstoichiometrically in the presence of nitric oxide-reducing substances at temperatures from 950° C. to 1,000° C.
Claim 3
Dependent Claim
27 words
Process according to claim 1, characterized in that the nitric oxide-reducing substances are added at least partially together with the reducing fuel into the first reduction zone.
Claim 4
Dependent Claim
25 words
Process according to claim 1, characterized in that the remaining time of the flue gases in the first reduction zone is at least 0.1 s.
Claim 5
Dependent Claim
26 words
Process according to claim 1, characterized in that the hyperstoichiometric conditions in the second reaction zone are adjusted by mixing combustion air into the flue gases.
Claim 6
Dependent Claim
30 words
Process according to claim 4, characterized in that the temperature range in the second reduction zone is adjusted by way of the volume and temperature of the added combustion air.
References Cited (Backward Citations)
JPS58120004A
Cited
JPS58156104A
Cited
JPS58190605A
Cited
EP0159492A2
Cited
WO1987000186A1
Cited
US4779545A
Cited
US5078064A
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US5078064B1
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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) | 1995-07-21 | 1996-01-20 | 1996-07-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-07-21 | 2000-01-20 | 2000-07-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-07-21 | 2004-01-20 | 2004-07-21 | $7700.00 | Window Closed / Lapsed |