xcept the lost of heat insulation layers. The surface of chock shaped blade has self-cleaning function. The relative movements of the product particles and the chocked shaped surface might clean the material attached to the chock shaped surface, so to keep the cleanliness of heat transferring surface during working. The shell of hollow blade dryer is shape. 2or4 pieces of hollow stirring shaft are usually equipped in the shell. To avoid any leakage of material, there're sealed terminal cover an