PURPOSE: To efficiently remove toxic gas by analyzing and adjusting automatically the alkalinity of liquid in a toxicity removing tower when the gas is removed by being neutralized with an alkaline substance in the tower.
CONSTITUTION: In a method in which a toxic gas (e.g. phosgene, hydrogen chloride, chlorine) is removed by being neutralized with an alkaline substance in a toxicity removing tower 1, the alkalinity of liquid in the tower 1 is measured with an analytical instrument 10 equipped with a colorimeter, and the valve 12 for feeding an alkaline substance is automatically operated by a signal from the colorimeter to adjust the alkalinity. As a result, the alkalinity of the liquid in the tower can be analyzed and adjusted correctly and automatically without the manual operation of the analysis and valve handling, which has been necessary so far, thereby enabling efficient removal of the toxic gas.
NAKAJIMA RYOICHI
GOTO SHOICHI
SAITO YASUHIRO
