US Patent 7942943 Biomass gasifier system with low energy and maintenance requirements

A down-draft fixed bed gasifier is disclosed that produced clean producer or synthesis gas. The gasifier can be installed at a stationary location or can be scaled down to enable placing the gasifier on a trailer that can be moved to the site of biomass generation. The gasifier is vertically oriented and generally cylindrical, and the design allows for a continual input of feedstock into the gasifier with less clogging and without lowering the gas pressure inside the gasifier. The design incorporates an internal catalyst to clean tars from the produced gas, and uses heat from the combustion chamber of the gasifier to heat the catalyst. The flow of air may be either positive flow or negative flow.