Predicting carbon conversion in fluidized bed gasification of biomass

There is increased interest in biomass gasification for production of a gas which can substitute for fossil fuel, for instance in lime kilns. High system efficiency requires good carbon conversion in the gasifier. When a solid fuel particle is injected into a hot fluidized bed, the reactivity of the resulting char in gasification reactions (between char carbon and steam and CO2 as well as the inhibiting reactions of product gases H2 and CO) play a significant role in reaching good carbon conversion. In this paper, the gasification reactivity data of biomass chars, as measured in TGA experiments, is used for the determination of kinetic parameters for char carbon gasification reactivity correlations. The complicated ash-carbon interactions during char gasification are currently being studied. Laboratory measured reactivity values from TGA experiments are used in the Carbon Conversion predictor to simulate carbon conversion in a real scale fluidized bed gasifier. The predictor is a relatively simple and transparent tool for the comparison of the gasification reactivity of different fuels in fluidized bed gasification. Simulations against some pilot-scale results show reasonable agreement.