| 摘要 |
<p>PURPOSE:To maintain stably the pH value of the liquid discharged from an oxidation column by controlling the amt. of the sulfuric acid to be introduced into the oxidation column in accordance with the control signal obtd. by arithmetic processing from the flow rate signal for the liquid to be oxidized, the pH signal of the liquid discharged from the oxidation column and an adjustment signal for the deviation of pH. CONSTITUTION:The amt. of the sulfuric acid to be introduced into an oxidation column 2 is controlled in accordance with the control signal phi for the amt. of the sulfuric acid to be supplied obtd. by the arithmetic processing using the equation by an arithmetic device 22 from the opening signal X of a control valve 16 for a flow rate controller for the liquid to be oxidized, the pH signal Y obtd. by measuring the liquid discharged from the oxidation column 2 with a pH meter 19, and the control signal Z of a controller 20 for the deviation of pH to which the pH value is inputted, in a wet type stack gas desulfurizer of a lime method which introduces waste gas contg. SO2 through a duct 6 into a desulfurization column 1, desulfurizes the same by spraying a circulating lime slurry therein, introduces part of said slurry as the liquid to be oxidized into the column 2 and produces gypsum by oxidizing the same with gas contg. sulfuric acid and oxygen contg. gas in said column. The pH of the liquid discharged from the column 2 is stably maintained even while load fluctuates and the recovery of gypsum having a high grade is made possible.</p> |
