Research progress of simulation methods of fluidization process in CFB based on meso-scale characteristics analysis

The accurate description of the gas-solid two-phase interaction,drag force,is the key to accurately predict the CFB gas-solid flow and chemical reaction by Euler / Euler method. The present study presents a series of heteroge- neous drag models and their application based on the energy minimum multi-scale method (EMMS) of a fluidization system. The cluster solids holdup,εsc ,was improved through the analysis of meso-scale characteristics,and then a new QC-EMMS drag model was developed. Through the experimental validation of different scales from grid to the macro- scale of reactor,the new model shows a high accuracy to reflect the law of non-uniform flow pattern with a large num- ber of clusters. On this basis,the paper further studies the pulsating characteristics and the probability density distribu- tion of local solids holdup,and the meso-scale characteristics such as the occurrence probability of clusters and the evolution law of a cluster,to enhance the understanding of gas-solid fluidization process.