US5809775A
Expired / Lapsed
US
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Reducing NOx emissions from an engine by selective catalytic reduction utilizing solid reagents
Assignee: Clean Diesel Technologies Inc
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Filing: 1997-04-02
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Granted: 1998-09-22
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Expires: 2017-04-02
Abstract
Abstract Urea or other solid NO x -reducing reagent is employed in a selective catalytic reduction process on emissions from diesel and lean-burn gasoline engines. The solid reagent is fed to a gas generator that produces a reactant gas by heating. In one embodiment the reactant gas is maintained at elevated temperatures to prevent condensation products from forming. The reactant gas contains ammonia and is fed to the exhaust on an as-needed basis.
Inventors
- 👤 Theodore J. Tarabulski
- 👤 Jeremy D. Peter-Hoblyn
- 👤 James M. Valentine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:26
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/206; F01N3/208; B; B01; B01D; B01D53/00; B01D53/34; B01D53/74; B01D53/86; B01D53/90; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9431; B01D53/9495; B01D2251/00; B01D2251/20; B01D2251/206; B01D2251/2062; F01N2240/00; F01N2240/20; F01N2240/25; F01N2560/00; F01N2560/06; F01N2610/00; F01N2610/02; F01N2610/06; F01N2610/10; F01N2610/14; F01N2610/1453; F01N2610/146; F01N2900/00; F01N2900/06; F01N2900/18; F01N2900/1806; F01N2900/1811; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
114 words
A method for reducing the emissions of NO x from a lean-burn engine having associated therewith an exhaust system having an exhaust passage leading to an SCR reactor effective for selective catalytic NO x reduction, comprising: supplying solid NO x -reducing reagent capable of generating ammonia-containing reactant gas upon heating, into a vessel having an outlet; heating the solid NO x -reducing reagent in the vessel at a temperature above the pyrolysis temperature for the reagent, to produce a reactant gas containing ammonia; introducing the reactant gas into the exhaust gas at an exhaust gas temperature effective for selective catalytic reduction; and passing the exhaust gas containing the reactant gas through an SCR reactor.
Claim 2
Independent Claim
114 words
A method for reducing the emissions of NO x from a lean-burn engine having associated therewith an exhaust system having an exhaust passage leading to an SCR reactor effective for selective catalytic NO x reduction, comprising: supplying solid NO x -reducing reagent capable of generating ammonia-containing reactant gas upon heating, into a vessel having an outlet; heating the solid NO x -reducing reagent in the vessel at a temperature above the pyrolysis temperature for the reagent, to produce a reactant gas containing ammonia; introducing the reactant gas into the exhaust gas at an exhaust gas temperature effective for selective catalytic reduction; and passing the exhaust gas containing the reactant gas through an SCR reactor.
Claim 3
Dependent Claim
25 words
A method according to claim 1 wherein the temperature of the exhaust gases is within the range of from about 180° to about 650° C.
Claim 4
Dependent Claim
54 words
A method according to claim 1 wherein the solid NO x -reducing reagent comprises a member selected from the group consisting of include ammelide, ammeline, ammonium cyanate, biuret, cyanuric acid, isocyanic acid, melamine, tricyanourea, urea, and mixtures of any number of these; and is heated to a temperature of at least about 300° C.
Claim 5
Dependent Claim
21 words
A method according to claim 3 wherein the reactant gas is maintained at elevated temperature until introduced into the exhaust gas.
Claim 6
Dependent Claim
24 words
A method according to claim 3 wherein the solid NO x -reducing reagent is heated to a temperature of at least about 400° C.
Claim 7
Dependent Claim
26 words
A method according to claim 1 wherein the solid NO x -reducing reagent is maintained under a pressure of at least about 50 psi during heating.
Claim 8
Dependent Claim
24 words
A method according to claim 1 wherein the solid NO x -reducing reagent is heated at least in part with heat from the exhaust.
Claim 9
Dependent Claim
25 words
A method according to claim 1 wherein the solid NO x -reducing reagent is heated at least in part with heat from an auxiliary heater.
Claim 10
Dependent Claim
71 words
A method according to claim 1 wherein the solid NO x -reducing reagent comprises a member selected from the group consisting of ammonium carbonate; ammonium bicarbonate; ammonium carbamate; ammonium salts of inorganic acids, including sulfuric acid and phosphoric acid; ammonium salts of organic acids, including formic and acetic acid; and mixture of two or more of these; and is heated to a temperature of from about 40° to about 150° C.
Claim 11
Dependent Claim
24 words
A method according to claim 1 or 9 wherein the temperature of the reactant gas is not maintained after it is formed by pyrolysis.
Claim 12
Dependent Claim
27 words
A method according to claim 1 or 9 wherein the reactant is introduced into the exhaust between exhaust valves of the engine and a turbocharger exhaust turbine.
Claim 13
Dependent Claim
24 words
A method according to claim 1 or 9 wherein the reactant gas is introduced into the exhaust in close-coupled relation with the SCR catalyst.
Claim 14
Independent Claim
114 words
An apparatus for reducing the emissions of NO x from a lean-burn engine having associated therewith an exhaust system having an exhaust passage leading to an SCR reactor effective for selective catalytic NO x reduction, comprising: means for supplying solid NO x -reducing reagent to a vessel having an outlet; means for heating the solid NO x -reducing reagent in the vessel at a temperature above the pyrolysis temperature for the reagent, to produce a reactant gas containing ammonia; means for introducing the reactant gas into the exhaust gas at an exhaust gas temperature effective for selective catalytic reduction; and means for passing the exhaust gas containing the reactant gas through an SCR reactor.
Claim 15
Independent Claim
114 words
An apparatus for reducing the emissions of NO x from a lean-burn engine having associated therewith an exhaust system having an exhaust passage leading to an SCR reactor effective for selective catalytic NO x reduction, comprising: means for supplying solid NO x -reducing reagent to a vessel having an outlet; means for heating the solid NO x -reducing reagent in the vessel at a temperature above the pyrolysis temperature for the reagent, to produce a reactant gas containing ammonia; means for introducing the reactant gas into the exhaust gas at an exhaust gas temperature effective for selective catalytic reduction; and means for passing the exhaust gas containing the reactant gas through an SCR reactor.
Claim 16
Dependent Claim
39 words
An apparatus according to claim 13, further including: means for maintaining the solid NO x -reducing reagent under pressure while it is being supplied to the vessel; and means for maintaining the reactant gas under pressure in the vessel.
Claim 17
Dependent Claim
90 words
An apparat us according to claim 13, further including: means to sense the temperature with the exhaust gas; means to generate a signal representative of the sensed temperature; means to sense the pressure of reactant gas; means to generate a signal representative of the sensed pressure; and means to compare the generated signals to referenced values and generate a control signal for controlling solid NO x -reducing reagent feed to the means for heating the solid NO x -reducing reagent and the feed of reactant gas to the exhaust gases.
Claim 18
Dependent Claim
16 words
An apparatus according to claim 13, further including: means to feed the solid reagent under pressure.
References Cited (Backward Citations)
US4188364A
Cited
US4268488A
Cited
US4403473A
Cited
US5215652A
Cited
US4892562A
Cited
US4891050A
Cited
US4854123A
Cited
US5266083A
Cited
US5034020A
Cited
WO1990007561A1
Cited
US5240688A
Cited
US5693300A
Cited
EP0487886A1
Cited
US5224346A
Cited
US5431893A
Cited
EP0615777B1
Cited
US5540047A
Cited
WO1997001387A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-09-21 | 2002-03-23 | 2002-09-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-09-21 | 2006-03-23 | 2006-09-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-09-21 | 2010-03-23 | 2010-09-22 | $7700.00 | Window Closed / Lapsed |