APPARATUS FOR CONTROLLING CONCENTRATION OF SO2 AT OUTLET OF WET WASTE GAS DESULFURIZATION EQUIPMENT

摘要

PURPOSE:To keep the concn. of outlet SO2 constant regardless of the load of a boiler, by detecting the concn. an pH value of outlet SO2 and changing the pH of a recirculation liquid corresponding to the detected values and, at the same time, controlling the flow amount of an absorbent. CONSTITUTION:The concn. of outlet SO2 is detected by the outlet SO2 concn. detector 15 arranged to an exhaust duct 9 after SO2-removal and the output signal thereof is inputted to a SO2 concn. regulator 16 and compared with a preset outlet SO2 concn. value to perform feedback control. The control signal of the SO2 concn. regulator 16 is inputted to an amplifier 17 and, subsequently, the output of the amplifier and a pH lower limit value are inputted to an adder to output a pH set value. Further, the pH of a recirculation liquid is detected by a pH detector 14 and the detection signal is inputted to a pH regulator 10 and compared with the pH set value to perform feedback control and, by the output signal from said regulator 10, the opening degree of a flow control valve 11 is controlled.