TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Components: The heating mechanism comprises a circulation mechanism for circulating a continuous flow of highly heated fluid within the rollers. Each roller has a circumferential wall made of heat-conducting material, and inner and outer circumferential surfaces. A body is coaxially mounted within the roller in close proximity to the circumferential wall. It has peripheral outlets and intake port(s). Conduits are provided for passing the highly-heated fluid through the intake port and out the outlets against the inner circumferential surface. First conduit is provided for injecting the highly heated fluid into the body through an axial aperture in the roller. Second conduit is provided for drawing the highly heated fluid out of the roller. The second conduit may be formed through a second axial aperture in the roller. It may coaxially surround the first conduit through the aperture. The extraction mechanism comprises condenser for condensing hot combustion gases into liquids and a drawing mechanism for drawing the liquids out of the enclosure. It further comprises a combustion residue-extracting mechanism. The extraction mechanism comprises an Archimedes screw (35). The feed mechanism comprises a chute having an exit above the space between the rollers; and mechanism for feeding dry heated steam into the chute. The biomass material is preheated by the steam into the chute before dropping between the rollers. The rotation mechanism comprises mechanism for turning the rollers in opposite directions from each other, and at slightly different speeds. The enclosure is hermetically sealed. The processing can be performed under controlled atmosphere. The apparatus further comprises hermetically sealable chamber adjacent to the enclosure; a closable passageway between the enclosure and chamber; and adjustment mechanism for adjusting the atmosphere in the chamber to that of the enclosure, whereby biomass material can be placed into the chamber, the chamber sealed, and its atmosphere adjusted before opening the passageway and admitting the biomass material into the enclosure.