After-treatment system and method for reducing emissions in diesel engine exhaust

摘要

An after-treatment system arrangement and method of operating the after-treatment system arrangement is provided for heating the exhaust gas of an internal combustion engine. The after-treatment system arrangement includes an oxidation device for catalytically oxidizing the exhaust gas and a port in the exhaust-gas stream for selectively introducing a controlled amount of oxygen into the exhaust gas in response to a condition of the exhaust gas. The introduction of oxygen can be selectively controlled in response to the temperature of the exhaust gas downstream of the oxidation device. Simultaneously or alternatively, the introduction of oxygen can be selectively controlled in response to the chemical composition of the exhaust gas. The air-to-fuel ratio of the exhaust gas may also be controlled to further facilitate heating of the exhaust gas. The after-treatment system arrangement can also be controlled to remove pollutant emissions from the exhaust gas.