Dynamic Mixing Process of Dissimilar Particles in Three-Dimensional Fluidized Beds

A comprehensive study on the dynamic mixing process of biomass particles and inert particles in a cylindrical fluidized bed is conducted. The particle mixing parameters at multipositions inside three-dimensional fluidized beds are obtained by a specially designed measurement system. The local particle mixing ratios and dispersion coefficients are analyzed. Particle mixing mechanisms, including the convection mechanism and diffusion mechanism, are analyzed based on variations of mixing ratios and dispersion coefficient at multipositions inside the beds. Results show that the averaged radial dispersion coefficient at half-radius ranges from 0.0038 to 0.026 m²/s, which is about 1.5 times of that near the wall. The averaged axial dispersion coefficient ranges from 0.004 to 0.056 m²/s, which is about 2.3 times the radial dispersion coefficient. The particle mixing at the center and top is mainly driven by a convection mechanism; meanwhile, particle mixing at the bottom and near the wall is mainly driven by a diffusion mechanism.