| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust emission control device capable of suppressing aged deterioration of a denitrification rate of NOx catalyst caused by deposition of ash dust.SOLUTION: In an exhaust emission control device for removing ash dust adhered to NOx catalyst 14 by injecting pressurized air into a casing 13 of a catalyst reactor 12 having the NOx catalyst 14 as a catalyst therein by an air injection nozzle 16, abnormal deterioration of the NOx catalyst 14 is determined and is notified to the outside when differential pressure &Dgr;P of exhaust gas between an upstream side and a downstream side of the NOx catalyst 14 is increased to be higher than differential pressure &Dgr;Pi of the exhaust gas between the upstream side and the downstream side of the catalyst in an initial state at same exhaust flow speed Ve for a first reference differential pressure increase amount &Dgr;Pt1 which is an allowable differential pressure increase amount or more. |
