Abstract: A spark-arresting module for disposition in a duct for hot stack gases comprising a rigid frame structured with spaced, parallel bars alternating with spaced, parallel slots, a shaft at the upstream side of the frame and parallel thereto, a plurality of blades provided with diametrically-located vanes fixed to the shaft for rotation therewith, said vanes being movable through the slots in shearing relation to the bars by rotation of the shaft and being so shaped that some portion of each blade is at all times situated between the bars and a motor for effecting rotation of the shaft.

Abstract: Apparatus for progressively burning biomass material comprising a retort defining a chamber, a linearly moving grate bed enclosed within the chamber with a space below and a space above for respectively supplying primary air to the lower side of the grate and for collecting gases generated by progressive distillation of the biomass material at the upper side of the grate. Primary air is supplied to the underside of the grate bed at different pressures lengthwise of the grate by a distribution chamber extending lengthwise of the grate of V-shaped cross section containing at its bottom a Venturi opening through which air is delivered to the distribution chamber from successive longitudinally-arranged plenum chambers which, in turn, are supplied with air through conductors connected to a primary air source, each of which contains a damper. The grate may be horizontal or inclined.

Abstract: A dryer for particulate material, especially wood chips, to render them suitable for burning comprising an enclosure, spaced baffle plates in the enclosure dividing the enclosure from bottom to top into three chambers; an intermediate drying chamber for holding a column of particulate material for drying and two air chambers, one on each side of the drying chamber. The baffles contain openings, the air chamber at one side contains a bottom opening through which drying air is supplied to the enclosure and the air chamber at the other side contains an opening at the top through which moist air is discharged from the enclosure.

Abstract: A reactor wherein a biomass is moved progressively downwardly along the upwardly facing side of an inclined grate supported with an enclosure comprising a retort, the rear and front walls of which provide, in conjunction with the grate, a plenum chamber at the downwardly facing side of the grate and a mixing chamber at the upwardly facing side of the grate, the said structure providing for converting the biomass by a process of destructive distillation to CO and ash characterized in that the grate is maintained at a temperature below the fusion temperature of the ash to prevent slagging of the ash by the expedient of supplying an excess of primary air to the plenum chamber at the lower end of the grate so that it flows upwardly along the downwardly facing side thereof, the surplus discharged at the top, providing the grate with a plurality of relatively small openings distributed throughout its length and breadth and providing fins at the downwardly facing side of the grate perpendicular to the plane of the u