Drying apparatus for granular materials and drying method for granular materials

A drying method in which granular materials in a drying tank are heated and dried, the method comprising:

• a drying procedure comprising storing the granular materials in the drying tank, drying the granular materials by blowing gas heated by a heater from a gas outlet provided at a lower region of the drying tank and by exhausting gas passing through a layer of the granular materials stored in the drying tank from an exhaust port provided at an upper end portion of the drying tank,
• wherein the granular materials in the drying tank are moved by a moving mechanism when temperature of the granular materials around the gas outlet exceeds a glass transition temperature in the drying procedure.

A drying apparatus in which granular materials in a drying tank are heated and dried, the drying apparatus comprising:

• a moving mechanism to move the granular materials in the drying tank, the moving mechanism having a return passage to return the granular materials on a lower side in the drying tank to an upper side in the drying tank;
• and
• a control section to control the moving mechanism so as to move the granular materials in the drying tank by returning the granular materials stored on the lower side in the drying tank to the upper side in the drying tank through the return passage upon determining that temperature of the granular materials around a heating portion in the drying tank exceeds a glass transition temperature.