APPARATUS FOR CONTROLLING PH OF ABSORBING TOWER IN WASTE GAS DESULFURIZING PLANT

PURPOSE:To obtain constant pH-response regardless of desulfurization load, by altering the proportional sensitivity of a pH controller as functions of desulfurization load and a pH set value. CONSTITUTION:The desulfurization load signal, which is obtained by multiplying the signals from an SO2-concn. detector 1 and an exhaust gas flow amount detector 12, and the pH set value signal from a first function operator 14 are inputted to a second function operator 21 to operate and output the proportional sensitivity K of a pH controller 22. The pH controller 22 employs the output of the second function operator 21 as proportional sensitivity and P, PI or PID control is performed from the pH detection signal of a recirculated solution and the pH set value signal to control the supply flow amount of an adsorbent. Because the proportional sensitivity K is altered in proportion to the CaCO3-concn. in a tank and the supply flow amount of the adsorbent is controlled corresponding to the CaCO3-concn. in the tank and constant pH response is obtained over an entire load range.