Dehumidifying dryer is mainly for hygroscopicity strong plastic (such as PET, ABS, PC, PA, etc.)to make a high efficiency of dehumidification operation. The dehumidifying dryer can be divided into single and centralized type. The single type dehumidifying dryer usually include drying machine, drying barrels. Single type is suitable for small amounts and variety materials of drying,the efficiency of it very high and it is very convenient and fast to change the materials. Centralized dryer includes a drying machine and several dry barrels, each dry barrels have independent heating controller, it can dry several different kinds of raw materials at the same time, and cooperate with the regulator to control each dry barrels of air flo