Patent ID: 7624570
Filing Date: 2009-12-01
Classification: B01D,F01N,F02D,Y02A,Y02T

Abstract:
1. A method of denitrating a LNT in an exhaust aftertreatment system, comprising: treating an exhaust stream from an internal combustion engine using an exhaust aftertreatment system that passes the exhaust through a fuel reformer and then the LNT; controlling a rate of fuel injection into the exhaust upstream from the fuel reformer to make the fuel-air ratio of the exhaust that enters the fuel reformer and then flows to the LNT a first value which is rich and at which the fuel reformer produces syn gas and denitration of the LNT begins; and controlling the fuel injection rate to progressively increase the fuel-air ratio of the exhaust entering the fuel reformer to a second value over the course of the denitration, whereby the rate of syn gas production by the fuel reformer and the concentration of syn gas in the exhaust entering the LNT are increased; wherein the control provides a predetermined progressive increase to the fuel-air ratio over a first part of the denitration from the first value, which is low, to the second value, which is substantially higher than the first value.