US4751065A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reduction of nitrogen- and carbon-based pollutants
Assignee: Fuel Tech Inc
•
Filing: 1986-09-10
•
Granted: 1988-06-14
•
Expires: 2006-09-10
Abstract
Abstract Disclosed is a process for reducing nitrogen oxides in an effluent from the combustion of a carbonaceous fuel under oxygen-rich conditions which minimize the production of carbon-based pollutants. A dispersion of a solution comprising at least one additive compound selected from the group consisting of guanidine, guanidine carbonate, biguanide, guanylurea sulfate, melamine, dicyandiamide, calcium cyanamide, biuret, 1,1'-azobisformamide, methylol urea, methylol urea-urea condensation product, dimethylol urea, methyl urea, dimethyl urea, and hexamethylenetetramine is injected into an effluent at a temperature above 1300° F., and preferably above 1500° F. The concentration of the additive compound in solution, the temperature of the effluent at the point of injection, and the size of the droplets in the dispersion, are selected to provide a reduction in nitrogen oxides. When urea is employed in combination with hexamethylenetetramine, the effectiveness of the urea is enhanced, particularly at temperatures 1800° F. and below.
Inventors
- 👤 Wayne E. Bowers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:49
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/54; B01D53/56
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
62 words
A process for reducing the concentration of nitrogen oxides in an oxygen-rich effluent from the combustion of a carbonaceous fuel, which process comprises injecting an aqueous solution comprising hexamethylenetetramine into the effluent while the latter is at a temperature of at least 1300° F. in amounts sufficient to provide a molar ratio of hexamethylenetetramine to nitrogen oxides of from 1:6 to 2:1.
Claim 2
Dependent Claim
62 words
A process for reducing the concentration of nitrogen oxides in an oxygen-rich effluent from the combustion of a carbonaceous fuel, which process comprises injecting an aqueous solution comprising hexamethylenetetramine into the effluent while the latter is at a temperature of at least 1300° F. in amounts sufficient to provide a molar ratio of hexamethylenetetramine to nitrogen oxides of from 1:6 to 2:1.
Claim 3
Dependent Claim
19 words
A process according to claim 1 wherein the ratio of hexamethylenetetramine to nitrogen oxides is from 1:4 to 1:1.
Claim 4
Dependent Claim
39 words
A process according to claim 1 wherein the solution is injected as a dispersion at a number of points, the droplets within the dispersion being within the range of from about 10 to about 10,000 microns Sauter mean diameter.
Claim 5
Dependent Claim
15 words
A process according to claim 3 wherein the droplets are greater than about 50 microns.
Claim 6
Dependent Claim
24 words
A process according to claim 1 wherein the dispersion is injected into the effluent at a temperature of from 2000° F. to 2500° F.
Claim 7
Dependent Claim
21 words
A process according to claim 5 wherein the solution comprises at least 80% solvent, based on the weight of the solution.
Claim 8
Dependent Claim
21 words
A process according to claim 6 wherein the solution comprises at least 90% solvent, based on the weight of the solution.
Claim 9
Dependent Claim
75 words
A process for reducing the concentration of nitrogen oxides in an oxygen-rich effluent from the combustion of a carbonaceous fuel, which process comprises injecting into said effluent while the latter is at a temperature of at least 1300° F. an aqueous solution of urea and hexamethylenetetramine at concentrations of urea and hexamethylenetetramine in the solution and of the solution within the effluent which are effective to reduce the level of nitrogen oxides in the effluent.
Claim 10
Dependent Claim
75 words
A process for reducing the concentration of nitrogen oxides in an oxygen-rich effluent from the combustion of a carbonaceous fuel, which process comprises injecting into said effluent while the latter is at a temperature of at least 1300° F. an aqueous solution of urea and hexamethylenetetramine at concentrations of urea and hexamethylenetetramine in the solution and of the solution within the effluent which are effective to reduce the level of nitrogen oxides in the effluent.
Claim 11
Dependent Claim
24 words
A process according to claim 8 wherein the temperature of the effluent is between 1300° F. and 1800° F. at the point of injection.
Claim 12
Dependent Claim
32 words
A process according to claim 9 wherein the solution is injected into the effluent in amounts sufficient to provide a molar ratio of hexamethylenetetramine to nitrogen oxides of from 1:6 to 2:1.
Claim 13
Dependent Claim
19 words
A process according to claim 9 wherein the ratio of hexamethylenetetramine to nitrogen oxides is from 1:4 to 1:1.
Claim 14
Dependent Claim
19 words
A process according to claim 8 wherein the weight ratio of hexamethylenetetramine to urea is from 1:3 to 3:1.
Claim 15
Dependent Claim
39 words
A process according to claim 8 wherein the solution is injected as a dispersion at a number of points, the droplets within the dispersion being within the range of from about 10 to about 10,000 microns Sauter mean diameter.
Claim 16
Dependent Claim
15 words
A process according to claim 13 wherein the droplets are greater than about 50 microns.
Claim 17
Dependent Claim
33 words
A process according to claim 13 wherein the dispersion is injected into the effluent at an effluent temperature of from 2000° F. to 2500° F. and the solution comprises at least 90% solvent.
References Cited (Backward Citations)
US3599427A
Cited
US3988113A
Cited
DE2630202A1
Cited
JPS5277877A
Cited
US4208386A
Cited
JPS53109866A
Cited
JPS53112273A
Cited
DE2752918A1
Cited
JPH1110490A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-06-14 | 1991-12-14 | 1992-06-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-14 | 1995-12-14 | 1996-06-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-14 | 1999-12-14 | 2000-06-14 | $7700.00 | Window Closed / Lapsed |