Assessment of Devolatilization Schemes in Predicting Product Yields of Biomass Fast Pyrolysis

Three devolatilization schemes to simulate biomass fast pyrolysis were tested and validated in this study. Fast pyrolysis is an attractive process in converting lignocellulosic biomass to valued products. Accurate numerical models can help understand the conversion process and be used for reactor design and optimization. This study used a numerical model that considered the multiphase hydrodynamics and chemical reactions of biomass fast pyrolysis. The gas and solid phases were simulated by using a multifluid model that considered multiple species in each phase. Three devolatilization schemes for biomass fast pyrolysis were incorporated into the model to simulate the tempo-spatial evolutions of all phases and species. The predicted product yields were compared and validated using experimental data. It was found that the best predictions were given by a scheme that used three components to represent biomass and also considered organic liquid cracking into gas. Under the reactor conditions studied, all three devolatilization schemes predicted relatively fast decomposition of biomass and the reactor hydrodynamics was not significantly affected by the specifics of the devolatilization schemes. Overall, an accurate devolatilization scheme to simulate the chemical changes of biomass particles is essential to predicting the product yield of biomass fast pyrolysis at the reactor scale. (C) 2014 American Institute of Chemical Engineers Environ Prog, 33: 756-761, 2014