Effect of cohesive particle addition on bubbling characteristics of gas-solid fluidized bed: Meso-scale mechanism

Due to the small particle size and large specific surface area, the cohesive particles affect the flow characteristics in a gas-solid bubbling fluidized bed. They can easily produce agglomerated and smooth heterogeneous flow under the different cohesive particle addition amounts. The influence of the cohesive particle amount on the bubbling characteristics was experimentally investigated for two typical cases: bed surface agglomerate and well-dispersed with the bed. The images of bubble rise were recorded by digital camera and processed by binarization to track bubble motion and obtained the bubble motion characteristics. An energy minimization multiscale (EMMS) model based on binary particle bubble was expanded to the flow of cohesive particles to reveal the basic mechanism of influence of the cohesive particle. By comparing the results predicted by the model with the experimental data, it is found that the change rules of bubble size and bubble rising speed are similar, which proves the feasibility of the newly developed EMMS model. A study of the structure shows that the addition of cohesive particles increases the size of the bubbles and inhibits the collapse of the bubble due to the reduction of the gas-solid resistance coefficient.