Ammonia is pumped into the ammonia absorption (neutralization) tower through the fan. The ammonia absorption tower mainly uses the relevant principles of hydrodynamics. The gas and absorption liquid are mixed in the pipeline. When the absorption liquid and gas are mixed and pass through the pipeline, the gas-liquid two-phase contact surface with the pipe wall is large, and the gas-liquid collides violently to make the gas-liquid fully mixed, and then fall into the circulating water tank with the gravity of the liquid to form ammonia. Due to the large inlet pipe and small outlet pipe of the absorption tower, micro positive pressure is generated in the tower, so as to achieve the purpose of efficient absorption.