CFD-DEM investigation of the fluidization of binary mixtures containing rod-like particles and spherical particles in a fluidized bed

In the energy conversion process, the inert bed material such as sand with spherical shape is usually added to the fluidized bed for the proper fluidization of the non-spherical biomass particles. Understanding fluidization of the binary mixtures containing the biomass and the bed material is therefore significant for better utilization of the biomass. To this end, CFD-DEM model is used to simulate the fluidization of the binary mixtures containing the rod-like particles that represent the light and large biomass particles and the spherical particles that represent the dense and small bed material, in which all particles are described by super-ellipsoid model. Five granular systems with different volume fractions of the rod-like particles but the same particle volume are simulated in this paper. The simulation results demonstrate that the minimum fluidization velocity would increase with the volume fraction of the rod-like particles. The addition of the spherical particles is beneficial to the fluidization of the rod-like particles. The mixing rate in binary granular system and the distribution of the coordinate number would be affected by the gas superficial velocity and the volume fraction of the rod-like particles. For the orientation of the rod-like particles, its distribution in binary granular system is different from that in monodisperse rod-like particle system. But whether in binary granular system or monodisperse rod-like particle system, there is apparent wall effect on the particle orientation. [Display omitted] •Fluidization of binary mixtures containing biomass and sand is studied by CFD-DEM.•The biomass can mix with the sand well at the rather high gas velocity.•Both biomass proportion and gas velocity affect the coordination number.•Orientation of biomass in binary mixture is different from that in monosized system.