| 摘要 |
PROBLEM TO BE SOLVED: To provide a drying device which realizes a more efficient drying process and reduces a moisture content beyond its conventionally accepted level under a simple constitution as well as a drying method using the drying device. SOLUTION: The interior of a tank 6 is temporarily opened to an atmosphere by opening an ON-OFF valve 19, an atmospheric vent value 32 and a supply valve 18, halfway through a process to vacuum-dry the granule loaded into the tank 6 with the help of a vacuum pump 23 while stirring the granule using a stirring blade 7 and at the same time, a drying medium such as nitrogen gas or dry air is introduced. When a temporary opening action is performed during the vacuum drying process, the moisture content put out by the expansion and shrinkage of the granule and the rapid compression of an expanded drying material, is replaced with the drying medium. This, compared to the case in which no temporary opening action is carried out, it is possible to more efficiently dry the granule and reduce the moisture content of the granule.
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