CFD simulation and performance optimization of a new horizontal turbo air classifier

Abstract

A new horizontal turbo air classifier equipped with two inclined air inlets has been introduced. The flow field and classification performance of the classifier have been investigated using CFD method and response surface methodology (RSM). Simulation results show that the flow field is composed of the primary swirling flow and the secondary upward washing air, and the uniformly distributed swirling flow occupies the classifying chamber. The tangential gas velocity reaches the maximum value on the outer surface of the rotor cage, generating strong centrifugal force for the particle classification. The discrete phase model (DPM) can predict the cut sizes, but cannot present the fish-hook phenomenon. The desirable experimental condition by targeting the cut size of 20 μm and minimizing the classifying accuracy index is, rotor speed of 1373.6 rpm, primary air volume flow rate of 261.8 m3/h and secondary air volume flow rate of 42.4 m3/h. The corresponding fine and coarse fraction loss are less than 1.42% and 7.24%, respectively. This study provides a new strategy to design the horizontal turbo air classifier.