Hydrodynamics of binary mixtures in a tapered gas-solid fluidized bed

Tapered fluidized-bed reactors are suggested for biomass catalytic pyrolysis in this work. Both experiments and computational fluid dynamics simulations on hydrodynamics are conducted in a two-dimensional bed with an overall taper angle of 43.8° by using rapeseed as biomass and resin as substitutable catalyst. The results show that the jet penetration depth decreases with increasing initial bed height or decreasing jet gas velocity. However, the jet penetration depth displays a first-increase and then-decrease tendency with increasing resin fraction or annular gas velocity. A comparison of hydrodynamics between measured and simulated data, including the stochastic nature of the jets, identifies that the simple non-viscous two-fluid model can be used to predict the jet behaviors of both mono-particle system and well-mixed biomass mixtures. The results provide fundamental information for the design and scale-up of tapered fluidized-bed reactors for solid biomass catalytic pyrolysis.