Technically, crystallizers are not dryers. They are used to convert PET from an amorphous, back to a crystalline state for re-processing.
The crystallizer consists of an insulated hopper with an agitator driven by a gear motor and a heater/blower. Amorphous material is loaded into the top of the hopper and is heated to about 180˚ F. while being agitated to prevent agglomeration.
The crystallizing process in a typical crystallizer can be and must be monitored carefully for success. Crystallization may occur in a few minutes up to about an hour, depending on the properties of the material being crystallized. Upon completion, the re-crystallized material, discharged from the base of the hopper may then be transported to a drying hopper where it is dried by a dual bed or desiccant wheel drying system. Then it can be processed into new products.
NOTE: The infrared drying system is a new technology gaining rapid acceptance for crystallizing and drying PET. You can accomplish both operations in one step in one hour with greatly reduced energy usage.