PROCESS CONTROL METHOD OF WET TYPE LIME GYPSUM METHOD EXHAUST GAS DESULFURIZATION APPARATUS

摘要

PURPOSE:To minimize the use amount of absorbents and stabilize the operation of the apparatus for a long time by incorporating the controls of the concentration of the unreacted absorbents and the rate of replenishment of absorbents in one system and controlling these simultaneously. CONSTITUTION:Folw rate 1 and SO2 density of gas B introlduced in the apparatus are converted to electric signals. According to these signals, an absorbent replenishment rate signal is outputted form IV and an absorption tewer extract liquid flow rate signal is outputted from III. The absorption tower extract liquid flow rate is controlled by a flow controller 6, control valve 6 and flowmeter 8. The sulfuric acid replenishment rate to a pH control tank 34 is calculated by the signals from the flowmeter 8 and unreacted absorbent concentration setter 8, is added with a pH measured value 12 and is controlled by a control valve 15. This sulfuric acid flow rate is converted 18 to an unreacted absorbent amount. The unreacted absorbent concentration is calculated 19 from the signal of the absorption tower extract liquid flow rate and is compared with the concentration of the setter 9. Its over- or under quantity is multiplied 21 by the absorption tower extract liquid flow rate to compute the over or under of the absorbent flow rate. To this added the absorbent replenishment rate signal IV, to which correction 25 is added and the absorbent replenishment rate is controlled by the controller 26, control valve 27 and flowmeter 28.