AMMONIA INJECTION CONTROLLER FOR DENITRATION REACTOR

摘要

PROBLEM TO BE SOLVED: To make it possible to suppress the NOx concn. in the outlet of a denitration reactor to an already set value or below by providing the apparatus with means for detecting a frequency in precedence to a rapid change in the NOx concn. in the gas to be treated by a frequency fluctuation and correcting the injection rate of ammonia by increasing or decreasing this rate. SOLUTION: This ammonia injection controller has the injection rate correcting means 59 for correcting the necessary ammonia flow rate signal 35 by increasing or decreasing the same in correspondence to the fluctuation rate of the frequency in precedence to the rapid change in the NOx concn. in the gas to be treated by the fluctuation in the frequency. This means previously calculates the corresponding load fluctuation rate in accordance with the fluctuation rate of the frequency fluctuation by a differentiator 62 from the AFC signal 61 transmitted by an AFC command 60 and the upper and lower limit values of the load fluctuation rate is limitted by an upper and lower limiter 63. A load command signal 52 based on a DPC command or ALR command with respect to this signal 64 is multiplied by a multiplier 65 to form an increase/decrease correction signal 66 for the ammonia injection rate, by which the bias correction of the necessary ammonia flow rate signal 35 is executed. As a result, the correction of the ammonia injection rate is added.