Study of air-steam gasification of spherocylindrical biomass particles in a fluidized bed by using CFD-DEM coupling with the multi-sphere model

In this work, a reactive CFD-DEM coupling with the multi-sphere model has been established and used to investigate the air-steam gasification of spherocylindrical biomass particles in a fluidized bed. Specifically, biomass particles are assumed to have a spherocylindrical shape while small inert bed materials (i.e., sand particles) have a spherical shape. Both kinds of particles are characterized by the multi-sphere model and each particle is individually tracked. Moreover, particle-particle collisions, heat convection, heat conduction, radia-tion, and homogeneous and heterogenous reactions during biomass gasification are all considered. After model validation, the effect of biomass particle aspect ratio on five different indicators (e.g., fluidization behavior, gas production, particle thermochemical conversion, particle height, and particle orientation) are systematically explored. Results show that the gas porosity near the fuel injection location is high due to the gas release of the injected biomass. Enlarging the particle aspect ratio can accelerate biomass conversion processes. In addition, more particles prefer to show a nearly vertical orientation in the fluidization region, and this orientation behavior can be enhanced by increasing the particle aspect ratio.

Automated summary

A reactive CFD-DEM coupling with the multi-sphere model is established and used to investigate the air-steam gasification of spherocylindrical biomass particles in a fluidized bed. The effect of biomass particle aspect ratio on various indicators is systematically explored, showing that increasing the particle aspect ratio can accelerate biomass conversion processes and enhance particle orientation behavior in the fluidization region.