Patent US4988285A successfully refreshed from Google Patents.
US4988285A
Expired / Lapsed
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Reduced Nox combustion method
Assignee: Praxair Technology Inc
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Filing: 1989-08-15
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Granted: 1991-01-29
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Expires: 2009-08-15
Abstract
Abstract A combustion method enabling reduced NO x formation wherein fuel and oxidant are separately injected into a combustion zone in a defined velocity relation, combustion gases are aspirated into the oxidant stream prior to intermixture with the fuel, and the fuel is maintained free from contact with oxygen until the intermixture.
Inventors
- 👤 Mark A. Delano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 20:46
CPC Classifications
F; F23; F23C; F23C7/00; F23C10/00; F23C9/00; F23C9/006; F23D; F23D14/00; F23D14/20; F23D14/22; F23L; F23L7/00; F23L7/007; F23C2202/00; F23C2202/40; Y; Y02; Y02E; Y02E20/00; Y02E20/34
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
147 words
A method for combusting fuel and oxidant to achieve reduced formation of nitrogen oxides, comprising: (A) heating a combustion zone to a temperature at least equal to 1500° F.; (B) injecting into the heated combustion zone a stream of oxidant at a velocity within the range of from 200 to 1070 feet per second; (C) injecting into the combustion zone, spaced from the oxidant stream, a fuel stream at a velocity such that the ratio of oxidant stream velocity to fuel stream velocity does not exceed 20; (D) aspirating combustion gases into the oxidant stream and thereafter intermixing the aspirated oxidant stream and fuel stream to form a combustible mixture; (E) combusting the combustible mixture to produce combustion gases for the aspiration of step (D); and (F) maintaining the fuel stream substantially free from contact with oxidant prior to the intermixture with aspirated oxidant of step (D).
Claim 2
Independent Claim
147 words
A method for combusting fuel and oxidant to achieve reduced formation of nitrogen oxides, comprising: (A) heating a combustion zone to a temperature at least equal to 1500° F.; (B) injecting into the heated combustion zone a stream of oxidant at a velocity within the range of from 200 to 1070 feet per second; (C) injecting into the combustion zone, spaced from the oxidant stream, a fuel stream at a velocity such that the ratio of oxidant stream velocity to fuel stream velocity does not exceed 20; (D) aspirating combustion gases into the oxidant stream and thereafter intermixing the aspirated oxidant stream and fuel stream to form a combustible mixture; (E) combusting the combustible mixture to produce combustion gases for the aspiration of step (D); and (F) maintaining the fuel stream substantially free from contact with oxidant prior to the intermixture with aspirated oxidant of step (D).
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein the combustion zone is heated to a temperature at least equal to 1700° F.
Claim 4
Dependent Claim
10 words
The method of claim 1 wherein the oxidant is air.
Claim 5
Dependent Claim
11 words
The method of claim 1 wherein the oxidant is oxygen-enriched air.
Claim 6
Dependent Claim
12 words
The method of claim 1 wherein the oxidant is technically pure oxygen.
Claim 7
Dependent Claim
14 words
The method of claim 1 wherein the oxidant contains at least 3 percent nitrogen.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein the oxidant velocity is within the range of from 500 to 1070 feet per second.
Claim 9
Dependent Claim
11 words
The method of claim 1 wherein the fuel is natural gas.
Claim 10
Dependent Claim
19 words
The method of claim 1 wherein the oxidant stream velocity to fuel stream velocity ratio is less than 10.
Claim 11
Dependent Claim
24 words
The method of claim 1 wherein the oxidant stream velocity to fuel stream velocity ratio is within the range of from 1 to 5.
Claim 12
Dependent Claim
36 words
The method of claim 1 wherein the fuel and oxidant streams are separated at their injection points into the combustion zone by a distance within the range of from 4 to 20 oxidant stream injection diameters.
Claim 13
Dependent Claim
17 words
The method of claim 1 wherein 2 or more oxidant streams are injected into the combustion zone.
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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) | 1994-01-28 | 1994-07-30 | 1995-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-28 | 1998-07-30 | 1999-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-28 | 2002-07-30 | 2003-01-29 | $7700.00 | Window Closed / Lapsed |