PURPOSE: To decrease the losses of an alkali absorbent by separating and removing the product of reaction formed on the surfaces of the reacted carriers emitted from a reacting chamber, carrying the alkali absorbent again on these carriers and repeatedly supplying the same into the reacting chamber.

CONSTITUTION: A reacting chamber 3 delineated by air pemeable partition walls 2 is provided in the gas passage of a gas reaction apparatus 1, and a feed hopper 4 is installed in the upper part thereof and a discharge port 5 in the lower part. Granular carriers are charged into a regenerating device 6 having an alkali soln. where they are adhered with the alkaline absorbent, after which they are transported to the feed hopper 4 while being dehydrated and are filled in the reacting chamber 3. When an exhaust gas cotg. harmful gases is admitted into the reaction apparatus 1, the harmful gases react with the alkali absorbents on the carrier surfaces and are thereby removed from the exhaust gas. This gas is then exhausted through an exhaust port 5. The product of reaction with the harfum gases produced on the carrier surfaces is stripped in a separating device 7, after this the carriers are fed again into the regenerating device 6 where the alkali absorbent is carried thereon, thus the process is repeated.