| 摘要 |
PURPOSE:To perform stable denitration causing no change in the concn. of NOx at the outlet of a denitration apparatus even if variation is generated in a boiler, in a denitration apparatus by NH3 used in treating exhaust gas from a coal burning boiler, by controlling the injection amount of NH3 corresponding to not only the total amount of NOx but also the change in a catalyst temp. CONSTITUTION:The total amount of NOx is obtained from the detection values of the NOx concn, detector 21 and the waste gas flow meter 22, both of which are provided at the inlet of a denitration apparatus, through a multiplier 23 and a theoretical NH3 demand amount 28 is obtained from said total amount of NOx through an NH3/NOx mol ratio setting device 24 and a multiplier 25. The result of the multiplier 23 is imparted to a differentiator 26 to obtain a load preceding signal 27. The detection value of the exhaust gas temp. detector 60 at the inlet of the denitration apparatus is converted to a catalyst temp. by a catalyst temp. simulator 61 and sent to a differentiator 62 and the change amount of NH3 possessed by a catalyst corresponding to the catalyst temp. is outputted. This output, the theoretical NH3 demand amount and the load preceding signal are sent to an adder 29 to obtain an optimum injection NH3 objective value and the injection control of NH3 is performed on the basis of said objective value. |
