Exhaust gas decontamination system and method of exhaust gas decontamination

Abstract

An exhaust gas decontamination system and a method of exhaust gas decontamination wherein in the regeneration of NOx occlusion reduction type catalyst with respect to a lean-burn engine or diesel engine, even in the instance of rich burning accompanied by EGR, the NOx released from the NOx occlusion reduction type catalyst can satisfactorily be reduced and purged to thereby exhibit a high NOx removal ratio. The exhaust gas decontamination system (1) provided with the NOx occlusion reduction type catalyst (30) includes control unit (C1) comprising normal control operation means (C10), regeneration control initiation judging means (C20), catalyst activation control operation means (C30) and rich-burn control operation means (C40) capable of lowering the concentration of oxygen in the exhaust gas so as to realize such a constitution that the catalyst is carried out just before rich burning accompanied by EGR. <IMAGE>

Description

technical field [0001] The invention relates to an exhaust gas purification system and an exhaust gas purification method, which are provided with a nitrogen oxide absorption and reduction catalyst in internal combustion engines such as diesel engines to purify nitrogen oxides in exhaust gas. Background technique [0002] Various researches and proposals have been made on NOx catalysts for reducing and removing nitrogen oxides (hereinafter referred to as NOx) in exhaust gases of internal combustion engines such as diesel engines and some gasoline engines, and various combustion devices. [0003] Among these NOx catalysts, there is a NOx absorption reduction type catalyst which is [0004] There are NOx absorbing substances and are used or discussed for use in exhaust gas purification of lean burn (lean burn) gasoline or diesel engines. [0005] This NOx absorption and reduction catalyst is different from the three-way catalyst, even if there is oxygen in the exhaust gas (he...

AI Technical Summary

Problems solved by technology

by the Figure 12 It can be seen that due to the rich (over-rich) combustion accompanied by EGR, at the beginning of the regeneration of the rich combustion operation for the regeneration of the NOx absorption and reduction catalyst, the peak of the NOx concentration is high, and the purification rate of NOx is greatly reduced.

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