Method for treatment of exhaust gases

摘要

This specification teaches a method for treatment of exhaust gases which if left untreated can generate, upon full oxidation, temperatures in a range of from about 1600 DEG F. to about 2700 DEG F. over an oxidizing catalyst. The method has the following steps. An internal combustion engine (10) is operated under conditions in which there is insufficient oxygen to oxide all the hydrocarbon present in the fuel. The exhaust gases so-developed are passed into an exhaust manifold (12) and then through an exhaust pipe (14) to an oxidation catalyst (16) whose primary oxidation catalyst is palladium. An air pump (20) generates a supply of oxygen which can supply up to about 80% of the oxygen required to combust fully all of the hydrocarbons and carbon monoxide contained in the exhaust gases when the internal combustion engine is operating in a wide-open throttle condition. A portion of the generated oxygen supply is directed by means of an air line (24) into the exhaust manifold where the oxygen oxidizes any of the hydrocarbons and oxidizes a portion of the carbon monoxide. A remaining portion of the generated oxygen supply is directed by an air line (26) into the exhaust gases in the exhaust pipe just prior to passing over the oxidation catalyst. When the internal combustion engine is operated at wide-open throttle conditions, all but a small amount of the carbon monoxide in the exhaust gases is fully oxidized and all of the oxides of nitrogen are reduced to nitrogen at a time when the internal combustion engine is producing a very large amount of oxides of nitrogen.