(27c) Multiscale Modelling of Biomass Fast Pyrolysis in Micro Fluidized Beds

Biomass provides a unique opportunity to produce sustainable and renewable carbon-based fuels. Fast pyrolysis of biomass is a robust technique to convert lignocellulosic biomass (non-food sources) into liquid fuels through rapid heating of biomass in the absence of oxygen. For this purpose, fluidized bed reactors (FBR) are commonly employed. A significant challenge in understanding and controlling biomass fast pyrolysis is the strong coupling among various chemical and physical processes over a wide range of spatial and temporal scales. For example, multiphase bed hydrodynamics determines the heating rate of biomass particles, which in turn impacts the biomass conversion into products. In this regard, CFD is a promising tool as it provides detailed insights into the underlying processes of biomass fast pyrolysis. However, a major limitation of present CFD simulations of biomass fast pyrolysis is the inadequate representation of small scales associated with chemical conversion processes. In this work, we focus on the multiscale aspect of biomass fast pyrolysis in a Micro Fluidized Bed Reactor (MFBR). To this end, chemical kinetics and intra-particle processes of biomass are coupled with reactor hydrodynamics. The reactor scale simulations are performed using a CFD-DEM approach incorporating the soft sphere collision model. The simulation predictions of product yield and composition are compared with the experimental results. The impact of bed hydrodynamics on the quality of bio-oil is also evaluated.