MOISTURE-CONTROLLING AND DRYING APPARATUS

PURPOSE:To constantly keep the equilibrium between the surface evaporation rate and the inner diffusion rate and to attain uniform drying speed throughout the surface and the inner part of the material to be dried, by controlling the partial water-vapor pressure while keeping the humidity around the drying object to saturated state. CONSTITUTION:A drying object 1 is placed on a weighing apparatus 12 in a chamber 13 and the chamber 13 is supplied with saturated steam adjusted to a prescribed pressure with a pressure regulating valve 14 to promote the diffusion in the drying object 1 and equilibrate the moisture content between the inside and the outside of the drying object. The saturated steam in the chamber 13 is slowly discharged through a diaphragm valve 16 to decrease the partial steam pressure and, at the same time, the pressure is decreased to the atmospheric pressure by the operation of the valve 16 so that the moisture content measured by the weighing apparatus 12 is varied corresponding to the variation of the partial steam pressure by a controller 15. The drain of the saturated steam, etc., in the chamber 13 is discharged through a trap 18 during the above procedure. On the other hand, the atmosphere in the chamber 13 is dehumidified with a dehumidifier 19 and dried by circulating through the chamber 13 with a blower 20. A selector valve 25 is operated to evacuate the chamber 13 with a rotary pump 21, a mechanical booster pump 22 and a diffusion pump 23 and LN2 is supplied to a cold trap 18 to completely remove the moisture in the chamber 13.