Abstract: The hot, saturated air is moved from a drying oven chamber through a substantially closed circuit first in a heat extraction path through a series of cooling stages to condense the solvent from the air, and then in a heat collection path in a cross-flow heat exchange relationship through some of the cooling stages to recover some of the heat, and the dried air is moved back into the drying oven. The heat extraction path extends generally in a downward sloped direction toward a solvent storage tank, and the solvent is condensed as it reaches the lower end of the path.