Apparatus and method for producing combustible gases from biomass

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 underside of the grate which extend into the flowpath of the primary air. The rear wall of the retort is spaced rearwardly from and parallel to the downwardly facing side of the grate and forms therewith a manifold for containing the primary air as it flows upwardly therein, a force draft fan provides for delivering the primary air to the lower end of the manifold chamber and a damper at each end of the manifold chamber provides for controlling the flow of primary air.