CO2 biomass fluidized gasification: Thermodynamics and reactivity studies

This study reports biomass gasification in a fluidized CREC Riser Simulator. Steam-CO2 and steam-inert gas were used as gasifier agents. Three biomass feedstocks were evaluated in terms of gasification performance, based on carbon conversion, product molar fraction, and H-2/CO ratios. Results showed that gasification bed temperature influences syngas yields, as well as tar formation. This is the case regardless of the gasifier agent used. It was also shown that steam-CO2 gasification significantly reduces tar formation while improving carbon conversion and increasing H-2 and CO yields. Experimentally-observed product molar fractions were compared with thermodynamic equilibrium model results. This thermodynamic equilibrium model accounts for biomass elemental composition, bed temperature, and gasifying agents. It was proven that for steam-CO2 gasification, the thermodynamic equilibrium model predictions are close to the experimental results obtained in the fluidized CREC Riser Simulator. It was also demonstrated that steam-carbon dioxide gasification leads to a zero CO2 gain, and therefore, a negligible carbon footprint.