Gasification characteristics of biomass in an internally circulating fluidized bed reactor

The effect of reaction temperature on the steam gasification rate of sawdust char was determined under isothermal conditions in a thermobalance reactor. On the basis of the unreacted shrinking core reaction model, activation energies and frequency factors found to be 34.3 kJ mol^-1 and 0.083 s^-1 in the chemical reaction control regime and 11.5 kJ mol ^-1 and 0.005 s^-1 in the pore diffusion control regime, respectively. To determine the sawdust gasification characteristics and to produce the medium calorific value gas, sawdust was gasified in an internally circulating fluidized bed gasifier with a draft tube. The effects of reaction temperature, oxygen/carbon molar ratio, steam/carbon molar ratio and sawdust feed rate on the product gas composition have been determined in the ICFB gasifier. The contents of hydrogen and carbon monoxide increase with increasing reaction temperature and sawdust feed rate. On the other hand, the steam/carbon molar ratio does not produce any significant effect on the gasifier performance. In the gasification zone, the product gas compositions are found to be H ₂ 44.0-50.0%, CO 23.6-32.1%, CO₂ 14.8-23.4% and CH ₄ 6.8-12.7% in the annulus section.