Fast pyrolysis of biomass in a spouted bed reactor: Hydrodynamics, heat transfer and chemical reaction

The present study focused on modeling the gas-solid multi-phase flow and pyrolysis reaction of biomass in a spouted bed reactor. For the first time, the kinetics of biomass pyrolysis in a spouted bed were measured by the micro-spouted bed thermogravimetric analyzer (MSB-TGA) and applied to the fast pyrolysis reaction during computational particle fluid dynamics (CPFD) analysis. The CPFD results of biomass pyrolysis show that, compared to conventional TGA, the kinetic data obtained by MSB-TGA provide reliable results for the pyrolysis reaction of biomass. The effects of reaction temperature and gas velocity on hydrodynamics, heat transfer, and the consequent pyrolysis reaction were also investigated. A significant change in pyrolysis product yield was observed as a result of enhanced mixing and heat transfer between bed materials and biomass particles by increasing the gas velocity. The tar yield increased to 64.8 wt% when the gas velocity was increased to 6 m/s, and then it decreased as the gas velocity exceeded 6 m/s. With increasing reaction temperature, the tar yield first increased and then decreased, with a maximum value of approximately 58.7 wt% at 450 °C. From 450 to 550 °C, the tar yield decreased from 58.7 wt% to 50.9 wt%, respectively.