| 摘要 |
PROBLEM TO BE SOLVED: To enhance reliability of exhaust emission control of an exhaust emission control device incorporating NOx catalyst and a bypass passage detouring the NOx catalyst. SOLUTION: This exhaust emission control device comprises a main NOx catalyst 20, a bypass pipe 26 detouring the NOx catalyst 20, and an auxiliary NOx catalyst 24 provided in the bypass pipe 26. An exhaust gas selector valve 28 for changing over the flow of exhaust gas, which is provided in the leading end of the bypass pipe 26, is controlled so that exhaust gas is led into the bypass passage 26 during regeneration of an SOx absorber to prevent the exhaust gas from flowing through the main NOx catalyst 20, but the exhaust gas is led through the main NOx catalyst 20 during non-regeneration of the absorber, so as to prevent the exhaust gas from flowing through the bypass pipe 26. With this arrangement, even though exhaust gas leaks into the bypass pipe 16 during on-regeneration of the absorber 17, the leaking exhaust gas is purified by the auxiliary NOx catalyst 24.
|
