Gasification of biomass with CO₂ and H₂O mixtures in a catalytic fluidised bed

Steam can be fully or partially substituted by CO₂ as a gasification agent. This substitution affects producer gas composition, char conversion and in-situ tar reforming. Here, wood chips were gasified in a spouting fluidised bed using silica sand and catalytic dolomitic lime as the bed material at 850 °C. The use of a gasifying agent composed of CO₂ and H₂O was compared to the use of CO₂ or H₂O alone. It was found that mixtures of CO₂ and H₂O as the gasifying agent improve char conversion, and that the combined gasification agents are very effective in ensuring the decomposition/destruction of tars when lime based materials are used in the fluidised bed.