Diesel Engine Nox Reduction

摘要

An engine system for treating nitrogen oxides present in an exhaust gas generated by the combustion of fuel. The engine system includes one or more long breathing lean nitrogen oxide traps that is/are configured to store at least a portion of the nitrogen oxide in the exhaust gas when the lean nitrogen oxide trap operates in an absorption mode. The lean nitrogen oxide trap is also configured for the conversion of the nitrates stored by the lean nitrogen oxide trap during a regeneration event. The engine-out nitrogen oxide levels may be reduced to extend the duration of the absorption process, thereby reducing both the frequency of regeneration events and the associated fuel penalty. The system may include primary and secondary exhaust gas recirculation systems, with exhaust gas from the secondary system being returned to the engine cylinder to reduce the level of nitrogen oxides in that exhaust gas.

主权项

1. An engine system for treating nitrogen oxides present in an exhaust gas generated by the combustion of fuel, the engine system comprising:
a diesel engine configured to generate the exhaust gas by the combustion of a fuel, the diesel engine calibrated for the generated exhaust gas to have, at least periodically, an engine-out nitrogen oxide level of less than around 100 parts-per-million; a lean nitrogen oxide trap configured to store at least a portion of the nitrogen oxide in the exhaust gas when the lean nitrogen oxide trap operates in an absorption mode, the lean nitrogen oxide trap configured for the conversion of a plurality of nitrates stored by the lean nitrogen oxide trap during a regeneration event, the adsorption process being, at least periodically, at least three times longer than that of a conventional LNT operating under similar conditions.