| 摘要 |
PURPOSE:To use a catalyst in the state of the highest efficiency of denitrification regardless of the presence of uncertain elements such as catalyst deteriorating soot, etc., by judging the state of deterioration of a catalyst and denitrification performance according to injection amount of NH3 and raising the temperature of a waste gas at the inlet of the catalyst stepwise. CONSTITUTION:As a catalyst 4 is deteriorated, the inject ion amount of NH3 from an NH3 spraying nozzle 6 is increased so as to keep the denitrification efficiency of said apparatus 3 higher than a prescribed value and then when the injection amount of NH3 becomes more than or equal to a prescribed value, the temperature of the waste gas at the inlet of the catalyst 4 is raised by a heater 2 and the injection amount of NH3 is decreased and again the injection amount of NH3 is increased as the catalyst 4 is deteriorated again. Like this, when the injection amount of NH3 reaches the prescribed value, the temperature of the waste gas at the inlet of the catalyst 4 is raised stepwise so as to keep said denitrification efficiency within a prescribed value. As a result, the catalyst can be used in the state of highest efficiency regardless of uncertain elements such as catalyst deteriorating soot, etc., thereby the service life of the catalyst can be lengthened remarkably. |
