Apparatus and method for moisture control of particulate material

摘要

Moisture content of material such as thermoplastic pellets (80) in a hopper (30) is controlled by supplying dehumidified air from a dessicant bed (90) to the hopper (30) and returning air from the hopper (30) to the dessicant bed (90). A dew point sensor (10) in the return air path determines the moisture content of the material (80) in the hopper (30), and when the dew point drops to a pre-set level, a diverter (134) causes the return air flow to bypass the dessicant bed (90) and to be re-supplied to the hopper (30) without dehumidification. Two dessicant beds are provided, one of which is on-process while the dessicant in the other is regenerated.