EXHAUST GAS DECONTAMINATION SYSTEM AND METHOD OF CONTROLLING THE SAME

摘要

An exhaust gas decontamination system capable of, at the time of reactivation of deteriorated catalyst with respect to sulfur poisoning of a direct reduction type NOx catalyst disposed on an upstream side, effecting combustion removal of PM trapped by DPF disposed on a downstream side with the use of emitted HC and CO; and a method of controlling the same. In particular, an exhaust gas decontamination system (10) comprising exhaust gas passage (2) and, arranged thereon in sequence from an upper side, direct reduction type NOx catalyst (3) for purging NOx in the exhaust gas and DPF with catalyst (4) for purging PM in the exhaust gas, wherein not only is the oxygen concentration in the exhaust gas reduced to substantially nil but also the temperature of exhaust gas is raised. The exhaust gas decontamination system (10) is so constructed that air supply system (5) is provided for feeding air (Aa) between the direct reduction type NOx catalyst (3) and the DPF with catalyst (4) during the reactivation of deteriorated catalyst with respect to sulfur poisoning of the direct reduction type NOx catalyst (3).