The raw flue gas enters the absorption tower from the lower part of the venturi, and the absorbent and water enter from the expansion section. The dust, absorbent and reaction products are collected and returned by the dust collector and recycled. A high concentration fluidized bed layer is formed at the lower part of the absorption tower, where the absorbent particles collide and abrade violently, and the reaction surface is constantly updated to promote the continuous deacidification reaction.