This invention relates to a compact vacuum dryer for quickly and economically drying objects such as grain, industrial raw materials and thrash
. The vacuum dryer includes a combined upper and lower chamber for accommodating the drying objects. A vacuum pump is connected to the upper chamber for drawing in air for creating the vacuum within the system. A direct heating apparatus is provided at one side of the combination of the upper and lower chambers to directly heat the drying objects. A dielectric heating apparatus indirectly heats the drying objects in combination with direct heating apparatus. A moisture removing apparatus is provided along a discharge passage between the upper chamber and the vacuum pump for preventing the vacuum pump from drawing in moisture from the chamber which may damage or disable the pump.
The vacuum dryer as recited in claim 1, wherein the dielectric heating means includes an oscillator for generating high frequency signals and a feeding pipe for feeding the high frequency signals into the combination of the upper and lower chambers.
The vacuum dryer as claimed in claim 2, wherein the agitating means includes a motor positioned on an exterior surface of the lower chamber and a fan rotatably connected to the motor located within an interior portion of the combination of the upper and lower chambers.
The vacuum dryer as claimed in claim 7, wherein the compression means includes a motor fixed to an exterior surface of the upper chamber for generating a rotating force, a shaft fixed to the motor for motion vertically forward and backward in response to operation of the motor, and a compression plate fixed at an end of the moving shaft opposite from the motor for compressing objects to be dried within the combination of the upper and lower chambers when the moving shaft moves forward.