The application provides a mixer of a U-shaped post-
processing device, which optimizes the structure of the mixer, further prolongs the mixing
stroke of the mixer, accelerates the rotating speed of the
airflow, makes the
urea and
ammonia fully react, and reduces the risk of
urea crystallization; an air inlet guide plate is arranged vertically at an air inlet; the
airflow entering from the air inlet is divided into two airflows by the air inlet guide plate and enters the
airflow channel between the inner cylinder and the outer cylinder; a channel separation plate is arranged in the airflow channel; the air inlet guide plate extends into the airflow channel; the air inlet guide plate and the channel separation plate separate the airflow channel into two parts; the inner cylinder is provided with a rotating flow fin, and a gap is left between the rotating flow fin and the outer cylinder; the inner cylinder is provided with an airflow inlet corresponding to the rotating flow fin; the inner cylinder is provided with a
urea airflow inlet corresponding to the channel separation plate; and the outer cylinder is provided with a urea
nozzle facing the urea airflow inlet.