Investigation of the segregation and mixing behavior of biomass in a bubbling fluidized bed reactor using a CPFD model

Abstract

Segregation of biomass in a gasification reactor is an inevitable problem that can jeopardize the advantages such as uniform temperature control and proper mass circulation, and good solid-gas contacting area of the fluidized bed. This work investigates the mixing and segregation behavior of the biomass in a bubbling fluidized bed using a Computational Particle Fluid Dynamic (CPFD) model. The model is simulated in the CPFD software Barracuda VR. The sand particles and wood chips are used as the bed material and biomass. The simulations are carried out with different volume percentage of the biomass at constant bed aspect ratio. The results show that the minimum fluidization velocity is decreased from 0.08 m/s to 0.06 m/s with the increase in biomass volume from 5% to 20% in the bed. The complete segregation of biomass occurs at the superficial gas velocity that is 3.5 times greater than minimum fluidization velocity. With the increase in superficial gas velocity, 0 ≥ 6. , the biomass again starts to mix with the bed material. However, the mixing of woodchips is mainly limited to the upper part of the bed.