Numerical simulation of particle classification in new multi-product classifier

Abstract

Most of current centrifugal classifiers can only obtain coarse products and fine products. With the development of industry, particles with different average particle sizes and narrower distribution widths are required. In order to obtain the product in a specified range, classification has to be carried out repeatedly, resulting in higher time and energy cost. For this problem, a novel air classifier that can obtain multi-product with different particle size was designed. Because of the different trajectories of particles with different sizes, particles are sorted and separated in the classifier and flow into different outlets, where a variety of products with increasing average particle size were obtained. There are many feasible matching schemes that the particles do not hit the classifier wall and make full use of classifier space. CFD is employed to investigate particles distribution law and flow field character at different matching schemes, the effect of particle classification at different particles distribution law. Classification size ratio (CSR) is used to evaluate separation effectiveness, the greater CSR, the better separation effectiveness. Experiment results show when the accelerating flow field velocity is 4m/s, the classifying flow field angle is 60°, the CSR at outlet 1∼5 is 3.99, 1.56, 0.96, 0.61, 0.5. As the accelerating flow field velocity increase from 4 m/s to 7 m/s, the separation effectiveness is slightly improved, CSR increase to 4.55, 1.77, 1.03, 0.68, 0.54. There are obvious differences in CSR between adjacent outlet, which shows a variety of products can be obtain in multi-product classifier.