CONTROLLING METHOD OF DESULFURIZING RATIO IN WASTE GAS DESULFURIZING APPARATUS APPLIED WITH WET LIME METHOD

摘要

PURPOSE:To make it possible to maintain a desired desulfurizing ratio, by controlling an absorbing liquid recirculating flow amount corresponding to an exhaust gas flow amount and the measured value of SO2 concn. in an exhaust gas in the inlet and the outlet of an absorbing tower. CONSTITUTION:The flow amount of a combustion exhaust gas 1 entering an absorbing tower 2 is detected by a flowmeter 21 and the flow amount signal thereof is outputted to a function generator 22 which in turn inputs the signal corresponding thereto to an adder 23. On the other hand, SO2 concentrations in the exhaust gas 1 and a purified exhaust gas 7 are respectively detected by SO2 densitometers 14, 15 to be inputted to an operator 24. A desulfurizing ratio is operated based on the SO2 concn. signals in the operator 24 to be inputted to a setting device 25. The obtained value is compared to a predetermined set value in the setting device 25 and an output signal is issued to the adder 23 corresponding to deviation. The adder 23 adds the signals from the generator 22 and the setting device 23 and the obtained signal is outputted to a flow controller 26 which in turn operates a regulating valve 27 to control a recirculating flow amount and the gas-liquid contact area in the absorbing tower 2 is controlled.