US4533364A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for flue gas conditioning with the decomposition products of ammonium sulfate or ammonium bisulfate
Assignee: Electric Power Research Institute
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Filing: 1983-02-01
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Granted: 1985-08-06
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Expires: 2003-02-01
Abstract
Abstract A method is provided for enhancing the efficiency of fly ash collection in an electrostatic precipitator by lowering the resistivity of the fly ash particles in the flue gas, comprising the steps of introducing an aqueous solution of ammonium sulfate or ammonium bisulfate into a slipstream of hot gas in a chamber external to the main flue gas duct wherein thermal decomposition is effected and distributing the decomposition products into the main flue gas stream exiting from the air preheater at a point upstream from the electrostatic precipitator.
Inventors
- 👤 Ralph F. Altman
- 👤 John P. Gooch
- 👤 Edward B. Dismukes
- 👤 Roy E. Bickelhaupt
- 👤 Robert S. Dahlin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:54
CPC Classifications
B; B03; B03C; B03C3/00; B03C3/01; B03C3/013
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
173 words
A method for conditioning flue gas containing suspended fly ash, comprising the steps of: a. diverting a slipstream of flue gas from a main flue gas stream at a point upstream from an air preheater located directly upstream of an electrostatic precipitator where the temperature of said main flue gas stream is in the range of about 700° F. to 1000° F., said diverted stream thereby having a temperature in the range of from about 700° F. to 1000° F.; b. introducing an aqueous solution of an ammonium salt selected from the group consisting of ammonium sulfate and ammonium bisulfate into said diverted flue gas slipstream thereby effecting thermal decomposition of said ammonium salt into its gaseous thermal decomposition products which include sulfur trioxide and ammonia; and c. returning said diverted flue gas slipstream to said main flue gas stream at a point between said air preheater and said electrostatic precipitator thereby distributing said gaseous thermal decomposition products into said main flue gas stream flowing between said air preheater and said electrostatic precipitator.
Claim 2
Independent Claim
173 words
A method for conditioning flue gas containing suspended fly ash, comprising the steps of: a. diverting a slipstream of flue gas from a main flue gas stream at a point upstream from an air preheater located directly upstream of an electrostatic precipitator where the temperature of said main flue gas stream is in the range of about 700° F. to 1000° F., said diverted stream thereby having a temperature in the range of from about 700° F. to 1000° F.; b. introducing an aqueous solution of an ammonium salt selected from the group consisting of ammonium sulfate and ammonium bisulfate into said diverted flue gas slipstream thereby effecting thermal decomposition of said ammonium salt into its gaseous thermal decomposition products which include sulfur trioxide and ammonia; and c. returning said diverted flue gas slipstream to said main flue gas stream at a point between said air preheater and said electrostatic precipitator thereby distributing said gaseous thermal decomposition products into said main flue gas stream flowing between said air preheater and said electrostatic precipitator.
Claim 3
Independent Claim
182 words
A method for conditioning flue gas containing suspended fly ash, comprising the steps of: a. diverting a slipstream of combustion air from a main combustion air stream exiting the upstream side of an air preheater after having passed through said preheater where the temperature of said main combustion air stream is in the range of about 700° F. to 1000° F., said diverted combustion air slipstream thereby having a temperature in the range of from about 700° F. to 1000° F.; b. introducing an aqueous solution of an ammonium salt selected from the group consisting of ammonium sulfate and ammonium bisulfate into said diverted slipstream of combustion air, thereby effecting thermal decomposition of said ammonium salt into its gaseous thermal decomposition products which includes sulfur trioxide and ammonia; and c. introducing said diverted slipstream of combustion air into a main flue gas stream at a point between said air preheater and an electrostatic precipitator located directly downstream of said air preheater, thereby distributing said gaseous thermal decomposition products into said main flue gas stream between said air preheater and said electrostatic precipitator.
Claim 4
Independent Claim
182 words
A method for conditioning flue gas containing suspended fly ash, comprising the steps of: a. diverting a slipstream of combustion air from a main combustion air stream exiting the upstream side of an air preheater after having passed through said preheater where the temperature of said main combustion air stream is in the range of about 700° F. to 1000° F., said diverted combustion air slipstream thereby having a temperature in the range of from about 700° F. to 1000° F.; b. introducing an aqueous solution of an ammonium salt selected from the group consisting of ammonium sulfate and ammonium bisulfate into said diverted slipstream of combustion air, thereby effecting thermal decomposition of said ammonium salt into its gaseous thermal decomposition products which includes sulfur trioxide and ammonia; and c. introducing said diverted slipstream of combustion air into a main flue gas stream at a point between said air preheater and an electrostatic precipitator located directly downstream of said air preheater, thereby distributing said gaseous thermal decomposition products into said main flue gas stream between said air preheater and said electrostatic precipitator.
Claim 5
Dependent Claim
21 words
A method according to claim 1 or 2 wherein said decomposition products from step (b) are transported through a heated duct.
Claim 6
Dependent Claim
22 words
A method according to claim 1 or 2 wherein said decomposition products from step (b) are transported through a thermally insulated duct.
Claim 7
Dependent Claim
24 words
A method according to claim 1 or 2 wherein said decomposition products are distributed into said main flue gas stream through a distribution manifold.
Claim 8
Dependent Claim
26 words
A method according to claim 1 or 2 wherein the aqueous solution of ammonium sulfate contains from about 5 to 45% by weight of ammonium sulfate.
Claim 9
Dependent Claim
26 words
A method according to claim 1 or 2 wherein the aqueous solution of ammonium bisulfate contains from about 5 to 80% by weight of ammonium bisulfate.
Claim 10
Dependent Claim
60 words
A method according to claim 1 or 2 wherein said aqueous salt solution is sprayed at a rate sufficient to produce a sulfur trioxide concentration from about 250 to 2500 ppm by volume and said sulfur trioxide is then distributed into the main stream of flue gas to produce a concentration therein from about 2.5 to 25 ppm by volume.
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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) | 1988-08-05 | 1989-02-04 | 1989-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-05 | 1993-02-04 | 1993-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-05 | 1997-02-04 | 1997-08-06 | $7700.00 | Window Closed / Lapsed |