FLUID BED HOG FUEL DRYER

摘要

FLUID BED HOG FUEL DRYER A fluidized bed process and apparatus for uniformly drying particulized wet wood material or waste, commonly called hog fuel, from in excess of 50% moisture content to a 30% level suitable for burning as boiler fuel without generating "blue haze" air pollution typical of conventional rotary dryers. The fluidized bed of this invention is divided into treatment zones by a baffle arrangement. The hog fuel flows substantially horizontally along a circuitous path through the treatment zones. Hot flue gases fluidize the bed of hog fuel and provide necessary drying heat. Fines portions from each zone are entrained by the drying gases and blown out of the vessel just as they achieve the desired level of dryness and before significant blue haze is generated. A cyclone recovers these fines as product. Gas pressure to each treatment zone is adjusted so that only the desired amount of hog fuel is blown from the bed with the balance proceeding to subsequent zones. Regulation of zone gas velocities is achieved by dividing the gas inlet plenum into compartments which coincide with zones requiring adjusted velocities. The dryer may use flue gas from a hog fuel boiler, and in turn dry the hog fuel being burned in that boiler, or it may use the hot gas from an independent combustion source. A particularly attractive arrangement is to mount the fluid bed dryer above a fluid bed combustor burning waste wood in a single vessel.