Method For Treating An Exhaust Gas
OwnerDorian Francis Corliss, IIinventor
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Abstract
A provision of assemblies and methods for treating an exhaust gas from an internal combustion engine. The treatment method comprises at least two catalyst stages. The exhaust gas is directed to a first stage catalyst. After the first stage catalyst, the exhaust is passed to an inter-catalyst stage comprising an exhaust cooling process and an oxygen enrichment process. Next, the exhaust is passed to a second stage catalyst for reducing carbon monoxide, ammonia and hydrocarbon concentration in the exhaust gas, before exiting via an outlet.
Claims24
A method for treating an exhaust gas discharged from a rich-burn, spark ignited engine, the method comprising the steps of:
- (a) controlling combustion of air-fuel mixture to produce an exhaust gas that is substantially free of oxygen;
- (b) passing the exhaust gas from the engine to a first stage catalyst for substantially reducing nitrogen oxide (NOx) and carbon monoxide concentration in the exhaust gas;
- (c) passing the exhaust gas resulting from step (b) to an inter-catalyst stage having
- (i) an oxygen enrichment process wherein oxygen containing gas is discontinuously injected at an injection point into the exhaust gas, and
- (ii) an exhaust cooling process wherein the exhaust gas is cooled to a predetermined temperature for inhibiting the generation of NOx in the second stage catalyst;
- and
- (d) passing the exhaust gas resulting from step (c) to a second stage catalyst for substantially reducing carbon monoxide concentration and optionally reducing ammonia concentration in the exhaust gas, before exiting via an outlet,
- whereby the concentration of NOx, carbon monoxide, and hydrocarbons in the treated exhaust gas that exits the second stage catalyst is substantially reduced.
An apparatus for treating an exhaust gas discharged from a rich-burn, spark ignited internal combustion engine, comprising:
- a first stage catalyst adapted to receive the exhaust gas from the engine and to substantially reduce NOx and carbon monoxide content in the exhaust gas;
- an inter-catalyst stage configured to enrich the exhaust gas with oxygen and cool the exhaust to a predetermined temperature prior to catalytic conversion;
- a second stage catalyst adapted to receive the exhaust gas from the inter-catalyst stage and to substantially reduce carbon monoxide content in the exhaust gas;
- and
- an outlet for allowing the treated exhaust to exit the apparatus,
- whereby the concentration of NOx, carbon monoxide, and hydrocarbons in the treated exhaust gas that exits the second stage catalyst is substantially reduced.
A method for limiting the generation of NOx on a second stage catalyst receiving an exhaust gas from a combustion device, the method comprising:
- (i) controlling combustion of air-fuel mixture to produce an exhaust gas that is substantially free of oxygen;
- (ii) providing a least one exhaust cooling stage where the exhaust gas is cooled to a predetermined temperature before being passed to the second of at least two catalyst stages, whereby the generation of NOx in the exhaust gas that passes over the second stage catalyst is substantially limited based on an average of measurements taken over an extended time period.
Dependencies are inferred from the claim text.