Effect of Parameters of Guide Vanes on Separation Characteristics in a Turbo Air Classifier

In this paper, the influence of angle and number of guide vanes on the classification performance in a turbo air classifier is investigated. In this paper, a two-fluid model coupled with a population balance equation was used to consider the classification characteristics. This model is superior to the DPM (Discrete Phase Model) method because the distribution of volume fraction and velocity vector along the grain size of each particle can be considered from the Eulerian point of view. First, the validation of the computational model was verified by comparing the calculation results with the experimental data of the previous study. Next, the classification characteristics with the change of the guide vane parameters in a turbo air classifier were investigated. The calculations were performed for the cases that the coarse particle exit was open and blocked. The number and angle of guide vanes had a significant effect on the classification efficiency when the coarse particle exit was blocked. For the guide vanes angle of 36°, the cut size (d<sub>50</sub>) decreases with the increase of the number of guide vanes. For 54°, cut size decreases with the increase of the number of guide vanes to 24, but it does not change for more than 24 and for 72°, the cut size shows a rather increasing trend when the number of guide vanes increases above 24. Also, in the case of the coarse particle exit opening, the number of guide vanes does not significantly affect the classification performance, in which case the fine particles are mixed with the gas and discharged to the coarse particle exit by 40%. The parameters of the guide vanes generally do not have a large influence on the classification sharpness index, but the classification sharpness index decreases when the angle of the guide vanes is 72° and the number of guide vanes is more than 36.