US4496306A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-stage combustion method for inhibiting formation of nitrogen oxides
Assignee: Kanadevia Corp
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Filing: 1984-04-18
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Granted: 1985-01-29
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Expires: 2004-04-18
Abstract
Abstract A method comprising injecting a primary fuel and air into a furnace to burn the fuel and form a first-stage combustion zone, the air being supplied at a rate in excess of the stoichiometric rate required for the combustion of the fuel, and injecting a secondary fuel into the furnace around or downstream of the first-stage zone at a rate approximately equal to the stoichiometric rate required for the consumption of the excess oxygen resulting from the combustion in the first-stage zone the fuel being diluted with the surrounding combustion gas and to form a second-stage combustion zone around or downstream of the first-stage zone.
Inventors
- 👤 Noboru Okigami
- 👤 Hiroshi Hayasaka
- 👤 Yoshitoshi Sekiguchi
- 👤 Harushige Tamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:03
CPC Classifications
F; F23; F23C; F23C6/00; F23C6/04; F23C6/045; F23C6/047; F23C2201/00; F23C2201/30
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
196 words
A multi-stage combustion method for inhibiting the formation of nitrogen oxides comprising injecting a primary fuel and primary air into a furnace at an upstream end thereof to burn the fuel and form a first-stage combustion zone downstream of said end, the primary air being supplied at a rate in excess of the stoichiometric rate required for the combustion of the primary fuel, so that a ratio of air actually provided to air stoichiometrically required for combustion is at least 1.4 in the first-stage combustion zone, and injecting only a secondary fuel in the absense of air into the furnace at said upstream end in a plurality of streams spaced from a location of injecting said primary fuel and primary air into the vicinity of the first-stage combustion zone at a rate approximately equal to the stoichiometric rate required for the consumption of the excess oxygen resulting from the combustion in the first-stage zone and diluting the secondary fuel with surrounding combustion gas prior to combusting with said excess oxygen to form a second stage combustion zone spaced from a location of injecting of said plurality of streams and in the vicinity of the first-stage zone.
Claim 2
Dependent Claim
196 words
A multi-stage combustion method for inhibiting the formation of nitrogen oxides comprising injecting a primary fuel and primary air into a furnace at an upstream end thereof to burn the fuel and form a first-stage combustion zone downstream of said end, the primary air being supplied at a rate in excess of the stoichiometric rate required for the combustion of the primary fuel, so that a ratio of air actually provided to air stoichiometrically required for combustion is at least 1.4 in the first-stage combustion zone, and injecting only a secondary fuel in the absense of air into the furnace at said upstream end in a plurality of streams spaced from a location of injecting said primary fuel and primary air into the vicinity of the first-stage combustion zone at a rate approximately equal to the stoichiometric rate required for the consumption of the excess oxygen resulting from the combustion in the first-stage zone and diluting the secondary fuel with surrounding combustion gas prior to combusting with said excess oxygen to form a second stage combustion zone spaced from a location of injecting of said plurality of streams and in the vicinity of the first-stage zone.
Claim 3
Dependent Claim
17 words
A method as defined in claim 1 wherein the secondary fuel is injected around the first-stage zone.
Claim 4
Dependent Claim
25 words
A method as defined in claim 1 wherein the secondary fuel is injected toward a location downstream of the combustion gas of the first-stage zone.
Claim 5
Dependent Claim
20 words
A method as defined in claim 1 wherein the secondary fuel is supplied to the furnace diluted with combustion gas.
Claim 6
Dependent Claim
18 words
A method as defined in claim 1 wherein the primary fuel is mixed with air prior to combustion.
Claim 7
Dependent Claim
35 words
A method as defined in claim 1 wherein the primary air is supplied at a rate equal to the stoichiometric rate required for the combustion of the whole amount of fuel supplied to the furnace.
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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) | 1988-01-29 | 1988-07-30 | 1989-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-29 | 1992-07-30 | 1993-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-29 | 1996-07-30 | 1997-01-29 | $7700.00 | Window Closed / Lapsed |