Design and cold model testing of a biomass gasifier consisting of two interconnected fluidized beds

A simple and efficient reactor, consisting of two parallel interconnected fluidized beds, is proposed for the air gasification of low density biomass, with a capacity of the order of a few MWth. Solids circulate through the system as a result of the different fluidizing fluxes maintained on each side of a partition plate which separates the two beds at their air inlets. The product fuel is suitable both for power generation, by means of an internal combustion engine, and for distributed gas utilities. A key feature of the design relates to the ability of the circulating solids inventory to carry with it the buoyant biomass particles, thereby opposing their tendency to segregate to the bed surface, and at the same time reduce the elutriation of fine carbon particles. Both of these conditions favour the yield and quality of the product gas. A cold model of the proposed reactor, designed and operated in accord with the dimensionless similarity criteria, confirms the feasibility of the proposed reactor configuration.