| 摘要 |
<p>PURPOSE:To keep the quality of formed gypsum well by calculating the concn. of CaCO3 in a tank and controlling the concn. of CaCO3 to a predetermined value without using an expensive CaCO3 concn. detector. CONSTITUTION:An inlet SO2 densitometer 18 an outlet SO2 concentration meter 21, a treated gas flowmeter 19, a pH meter 29 detecting the pH of the falling soln. in an absorbing tower and a circulating soln. flowmeter 20 are provided to the absorbing tower 1. Further, a subtractor 22 subtracting outlet SO2 concn. from inlet SO2 concn., a first multiplier 23 multiplying the output of the subtractor 22 by the flow rate of gas, a hydrogen ion concn. operator 24 calculating the concn. of a hydrogen ion from the pH of the falling soln., a divider 25 dividing the output value of the multiplier 23 by the output value of the operator 24, a second multiplier 26 multiplying the output value of the divider 25 by the flow rate of a circulating soln., an amplifier 27 multiplying the output value of the multiplier 26 by a constant and a regulator 28 setting the output value of the amplifier 27 to control quantity to regulate the opening degree of the flow rate regulating valve 10 to absorbent supply piping 11 are provided.</p> |
