Study on fine powders discharged from hopper based on interparticle interactions analysis

The fluidity characterization and hopper discharge experiments were carried out with glass beads, fluidized bed cracking catalyst particles, lignite and PVC particles as experimental materials. The study found that the fluidity of different powders is quite different, and the corresponding gravity discharging results are also different. The flow rate of the powder used in the experiment is much lower than that predicted by the traditional Brown and Richards model. The analysis shows that the cohesion and agglomeration caused by the interaction between particles is the main reason that hinders the flow of fine powders. Based on the above analysis, the tensile strength of the bed is obtained by shear test combined with the theory of molar stress circle. Meanwhile, with the help of the model between the interaction between particles and the bed stress of powder constructed by Rumpf equation, the interaction force between particles can be obtained. Finally, the Bond number is used to modify the voidage of the powder bed, and the influence of the interaction between particles on the structure of the powder bed is revealed. On the basis of that the prediction model of powder mass flow rate is established. The newly established powder flow rate model coupled with the force between particles has effectively improved the disadvantage of the traditional model for the high prediction value of the fine particle powder flow rate, and significantly reduced the flow rate prediction deviation. © 2021, Chemical Industry Press Co., Ltd. All right reserved.