Investigating Impeller Wear and Its Effect on Pump Performance Using Soft Materials

Abstract

This project investigated the abrasive wear problem that commonly occurs in slurry pump impellers. The manufacturers’ stock impellers were replaced by samples with the same geometry and fabricated using rapid manufacturing technology (3D printing technology). Soft materials which are often used in 3D printing were selected to build the samples. Garnet-water slurries were employed as the test slurry. Wear experiments with different wear time were conducted for five rotational speeds (1050, 1200, 1350, 1500 and 1750 rpm) and three solid concentrations (5wt.%, 10wt.% and 15wt.%). Pump performance tests were conducted using impellers with different damage conditions.Using samples with soft materials saves time and costs, and can obtain acceptable similarity to normal conditions. The frequently worn spots are at the upper edge of the blades and near the hub. The solid concentration and flow rate will affect impeller wear rate. The flow rate has a dominant effect. The solid concentration and flow rate have a power relationship with the wear rate. The exponents of flow velocity for 5wt.% and 10wt.% are 2.5152 and 2.9403, respectively. The exponents of concentration for 1050 rpm and 1200 rpm are 1.5153 and 0.5168, respectively. The results in this work are reasonably consistent with previous studies using harder materials. Damaged impellers affect pump performance. A parabolic fit was imposed to describe the head and flow rate relationship. An empirical model was proposed to predict the pump head with damaged impellers. This project found an affinity law for different damage conditions of a certain impeller and coefficients C in the parabolic fitting functions. The exponent of the affinity law is in the range of 2.5 to 3, and depends on the damage conditions of the impellers. Hydraulic power will also be affected by abraded impellers. When the rotational speed is high, the damage impeller has less effect on pump performance than when the rotational speed is low.