Study of particle transport behaviour in a multi-chamber biomass pyrolysis reactor

This study optimized a multi-chamber biomass pyrolysis reactor for the thermal decomposition process of 0.75mmpoplar wood chips at 550 °C, considering the variation in particle properties throughout the biomass pyrolysis process and the change in residence time at each pyrolysis stage. Unsteady state calculations of gas-solid two-phase flow in the reactor under ambient conditions were primarily conducted using FLUENT 19.0 fluid simulation software. The study investigated the impact of gas velocity and chamber design on the alterations of solid-phase particle transport characteristics and fluidization properties. It delved into the migration of poplar wood chip particles during the pyrolysis process in the multi-chamber fluidized bed, selecting the optimal fluidization gas velocity for particles in each stage to enhance fluidization efficiency. The performance of the reactor was optimized by adjusting and modifying the inlet gas velocity of each chamber of the pyrolysis reactor. The results indicated that the best fluidization effect of particles and effective suppression of particle back-mixing were achieved in the first three chambers with inlet gas velocities of 0.40m/s, 0.42 m/s, and 0.39 m/s, respectively. This reduction in secondary pyrolysis of biomass particles led to increased bio-oil yield. This study provides a new approach for the design of biomass fast pyrolysis reactors, which is significant for the efficient utilization of biomass energy and the expansion of bio-oil production scale.