Gas-solid flow characteristics of fluidized bed with binary particles

The fluidization behavior of binary mixed particles is investigated, which is important for improving the performance of dense gas-solid fluidized bed systems. Based on the coupling of computational fluid dynamics and the discrete element method (CFD-DEM), analysis of the changes in bubble shape and particle motion characteristics under the condition of mixing different ratios of coarse particles in the fluidization process. The reliability of the numerical simulation results was verified by high-speed photographic experiments. The results show that an increase in the coarse particle mixing ratio leads to a delay at the moment when oscillatory delamination of particles starts to occur during fluidization. The oscillation of the particles started at 500 ms in both the experiment and simulation with a 5:5 mixing ratio of 5 mm and 3.5 mm particles. The difference in the diameter of fine particles and the percentage of coarse particles in the mixed particles both affect the formation of C-shaped bubbles. The inlet mass flow rate is 0.007 kg/s, while the overall bed height gradually decreases. Under different blending ratios, the intersection of the average velocity curves along the Z-axis intersects around zero at 400 ms, and the average velocity value is negatively correlated with the blending ratio. This investigation can provide a reference for the optimal design of fluidized beds, especially for biomass applications with binary particles.