Vacuum-type automatic dehumidifying and drying apparatus for powdered or granular material

A vacuum-type automatic dehumidifying and drying apparatus for powdered or granular material such as a pelletized or powdered resin or the like, provided with a drying hopper connected to an evacuating means having at its bottom a material discharge valve, and with a material collector communicating with the drying hopper via a material feed valve above the drying hopper for collecting the powdered material therein comprising;

• a double constructed drying hopper having a cylindrical main body made of a high heat conductivity material provided on its inner peripheral surface with plural fins, which define compartment walls, projecting inwardly and on its outer peripheral surface with a heating means surrounding said cylindrical main body, said hopper being constructed such that said main body is outwardly enclosed with a heat insulation wall,
• an outer air inlet provided with said main body for introducing outer air into said drying hopper,
• a material sensor in said hopper for detecting amount of the material stored in said hopper, and
• an evacuating means connected to said main body for evacuating said main body,
• whereby powdered material which is fed and stored in said drying hopper until said material sensor is turned off is heated in said main cylindrical body by driving said heating means while keeping said drying hopper vacuum by said evacuating means during dehumidifying and drying process, while required amount of dehumidified and dried powdered material in said drying hopper is discharged by opening the material discharge valve after said drying hopper is returned to an atmospheric pressure condition by opening said outer air inlet, and sequentially powdered material is fed again from the material collector to said hopper for next dehumidifying and drying process by opening said material feed valve until said material sensor is turned off.