US 6,066,303 AGranted

Apparatus and method for reducing NOx from exhaust gases produced by industrial processes

AssigneeNoxtech, Inc.

InventorsBruce C. Sudduth, Ralph J. Slone, Vishwesh Palekar, Madhu Ramavajjala

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Abstract

Gas-phase methods and systems for reducing NOx emissions and other contaminants in exhaust gases, and industrial processes using the same, are disclosed. In accordance with the present invention, hydrocarbon(s) autoignite and autothermally heat an exhaust gas from an industrial process so that NH.sub.3, HNCO or a combination thereof are effective for selectively reducing NOx autocatalytically. Preferably, the reduction of NOx is initiated/driven by the autoignition of hydrocarbon(s) in the exhaust gas. Within the temperature range of about 900-1600.degree. F., the introduced hydrocarbon(s) autoignite spontaneously under fuel-lean conditions of about 2-18% O.sub.2 in the exhaust gas. Once ignited, the reactions proceed autocatalytically, heating the exhaust gas autothermally. Under some conditions, a blue chemiluminescence may be visible.

Claims45

Dependent claims

A method for reducing pollutants including NOx in an exhaust gas, comprising the steps of:

generating the exhaust gas and controlling the initial temperature and composition of an exhaust gas in the ranges of about 900-1600.degree. F. and about 2-18% O.sub.2, respectively effective for autoignition of hydrocarbons;
controlling the introduction of hydrocarbons to autoignite and release heat autothermally effective for self-sustaining autocatalytic reactions under fuel-lean conditions wherein the exhaust gas contains at least 1% O.sub.2 and is heated to a final temperature in the range of about 1400-1550.degree. F.;
and
introducing one or more reductants for NOx into the exhaust gas wherein NH.sub.3, HNCO or a combination thereof are generated from the reductant(s);
wherein the autothenmal heating results in autocatalytic conditions effective for reducing the NOx and substantially depleting the NH.sub.3, HNCO and hydrocarbons and any by-product CO.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/211,879Filed 14 Dec 1998 · continuation
Priority: 1 Nov 1996
Granted: 23 May 2000
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

B01D 53/56
Nitrogen compounds: nitrogen oxides
B01D 53/62
Removing components of defined structure: carbon oxides
B01D 53/72
Removing components of defined structure: organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons
Y10S 423/05
Chemistry of inorganic compounds: automatic, including computer, control