Patent ID: 7891115

Claim:
A material drying apparatus for removing moisture from material positioned in the interior of an envelope, the envelope having an opening, the material drying apparatus comprising: an inlet structure configured to be in fluid communication with the opening of the envelope and the interior of the envelope; an air removal assembly configured to remove air from the interior of the envelope when the inlet structure is placed in fluid communication with the opening; a moisture removal assembly for removing moisture from gases removed from the interior of the envelope, the moisture removal assembly defining a fluid path from the inlet structure that is bifurcated into two alternate path portions, the moisture removal assembly comprising: a first moisture removal structure for removing moisture from gases moving along a first path portion, the first moisture removal structure comprising a first housing having an interior, a first heat exchanger positioned in the interior of the first housing, a first inlet valve for controlling gas flow into the first housing, a first outlet valve for controlling gas flow out of the first housing; a second moisture removal structure for removing moisture from gases moving along a second path portion, the second moisture removal structure comprising a second housing having an interior, a second heat exchanger positioned in the interior of the second housing, a second inlet valve for controlling gas flow into the second housing, a second outlet valve for controlling gas flow out of the second housing; and a heat pump for transferring heat in a selected direction between the first and second moisture removal structures, the heat pump alternately heating the heat exchanger of one of the moisture removal structure and cooling the heat exchanger of the other one of the moisture removal structures; a control apparatus for controlling operation of the first and second moisture removal assemblies and the heat pump, the control apparatus being configured to sense a condition of the apparatus and reverse operation of the heat pump upon detecting that the condition has passed a predetermined level.