Method and apparatus for energy efficient drying

A method of drying moist material in a drying location within an enclosure, comprising the steps of introducing a batch of material to be dried into the enclosure, recirculating between a heat source located within the enclosure and the batch of material a gas which initially fills the enclosure, whereby said gas becomes heated and produces steam from the moisture in the material, the heating of said moisture in the material constituting substantially the sole source of steam in the enclosure during recirculation, which steam increasingly displaces the initial gas from the enclosure while continuing to be heated by recirculation past said heat source, thereby becoming superheated, until substantially superheated steam alone is being recirculated, continuing to recirculate the superheated steam until the material reaches a required dryness, while allowing a portion of the steam to be discharged from the enclosure through a vent and recovering at least part of the thermal energy of the discharge steam outside of the enclosure, and then removing the batch of dried material from the enclosure, said enclosure being thermally insulated and substantially gas-tight, at least while the step of recirculating the superheated steam is being carried out, except for said vent allowing said discharge of a portion of the steam.