The air flow in the dryer outlet duct is usually hot air. The airflow dryer uses high-speed hot airflow to suspend wet materials in it. It has the characteristics of high heat transfer coefficient, large heat transfer area, and short drying time. During the drying process, the hot air is heated by the heater and then enters the dryer. The rotating hot air contacts the wet materials falling through the feeder, causing the surface layer of the wet materials to dry quickly.