Prediction of impeller nose wear behaviour in centrifugal slurry pumps

Abstract

Slurry pump design is governed by wear effects, which influence the pump's performance, reliability and maintenance costs. One of the highest areas of wear occurs in the impeller suction sealing area. Because of the occurring leakage flow rate and its corresponding high velocities in the nose sealing gap, it wears out much faster than most of the other wet end parts do and sets the service intervals. Moreover, increased nose wear leads to a significant increase in leakage flow rate, and a dramatic reduction in pump efficiency. In order to predict the influence of different impeller design parameters on the wear behaviour of the impeller suction sealing, a simple model was developed. Therein, the velocity field in the impeller suction side and sealing gap is calculated. The local wear intensity is predicted with respect to the acting velocities and fluid materials properties. Starting with certain sealing gap geometry, it is assumed that the predicted wear intensity remains constant for a certain time step, leading to a new (worn) geometry. By repeating this procedure the evolution nose gap wear behaviour with time can be predicted. Using this model the influence of different design parameters on the nose wear behaviour were analysed and discussed in the paper. A comparison of the calculated wear with actual field case data is reported.