| 摘要 |
PROBLEM TO BE SOLVED: To realize continuous operation and miniaturization or the like in a vacuum dryer. SOLUTION: A screw conveyor 2 is provided inside a vacuum tank 7 so as to be rotatable in both normal and reverse directions by a drive means. The screw conveyor 2 comprises a first screw 3 which is positioned in a thrown in port 14 side for an object to be dried, a second screw 4 which is inversely wound with respect to the first screw and has a large pitch, an agitation plate which is formed within a range of the length of the second screw, and a third screw 5 which is positioned in a discharge port 11 side of a dried product and is wound in the same direction as the second screw. The pitch of the first screw 3 is the same as that of the third screw 5. The length of the first screw 3 and that of the third screw 5 is twice as long as the pitch. The pitch of the second screw 4 is six - seven times as long as that of the first screw 3. The length of the second screw 4 is a half as long as the pitch of the second screw.
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