Experiments and Computational Particle Fluid Dynamics Simulations of Biomass Gasification in an Air-Blown Fluidized Bed Gasifier

Abstract

Experiments were performed in a pilot-scale bubbling fluidized bed gasification reactor with air as a fluidizing agent. Birch wood chips and sand particles were used as biomass and bed materials. Average molar product gas composition was 0.214 of CO, 0.212 of CO2, 0.103 of H2, 0.074 of CH4 and 0.397 of N2. A kinetics-based model was developed for the gasification process and simulated using commercial software Barracuda®. The model is validated against the measured gas compositions. The validated model was used to study the product gas compositions for olive waste and straw pellets. The effects of equivalence ratio (ER) on the product gas composition for birch wood was also studied in one of the simulations. Birch wood gave the highest (20.5 mole %) CO production rate and lowest (9.0 mole %) H2 production rate. The product gas flow rate was 1.96 Nm3 per kg of biomass and the lower heating value of the product gas was 6.65 MJ/Nm3. The CO concentration decreased from 25 to 13.2 mole %, whereas CO2 concentration increased from 17 to 19.5 mole % when increasing ER from 0.2 to 0.3. The CO and H2 concentrations for the olive waste were 8.1 and 56.1 mole %. The CO and H2 concentrations for the straw pellets were 6 and 73.4 mole %.