An Investigation of the Erosion Wear of Pitched Blade Impellers in a Solid-Liquid Suspension

T Jirout,I Fořt

doi:10.14311/1031

Abstract

This paper reports on a study of the erosion wear mechanism of the blades of pitched blade impellers in a solid-liquid suspension in order to determine the effect of the impeller speed n as well as the concentration and size of the solid particles on its wear rate. A four-blade pitched blade impeller (pitch angle α = 30°), pumping downwards, was investigated in a pilot plant fully baffled agitated vessel with a water suspension of corundum. The results of experiments show that the erosion wear rate of the impeller blades is proportional to n2.7 and that the rate exhibits a monotonous dependence (increase) with increasing size of the particles. However, the erosion rate of the pitched blade impellerreaches a maximum at a certain concentration, and above this value it decreases as the proportion of solid particles increases. All results of the investigation are valid under a turbulent flow regime of the agitated batch.

Highlights

In all areas of particulate technology where solid particles are handled, structures coming into contact with particles exhibit wear
The values increase with increasing impeller speed
A two-parameter equation describing the shape of a worn blade during the erosion process of a pitched blade impeller in a solid-liquid suspension of higher hardness was investigated

Summary

Introduction

In all areas of particulate technology where solid particles are handled, structures coming into contact with particles exhibit wear. A major constraint of high intensity agitation is the possibility of developing erosion wear of the impeller blades due to the presence of solid particles in the liquid. All particles cause some wear, but in general the harder they are, the more severe the wear will be [3]. The erosion of a pitched blade impeller caused by particles of higher hardness (e.g. corundum or sand) can be described by an analytical approximation in exponential form of the profile of the leading edge of the worn blade (Fig. 1). Where the dimensionless transversal coordinate along the width of the blade is H = y(r) (2). H and the dimensionless longitudinal (radial) coordinate along the radius of the blade r is R = 2r .

Methods

Results

Conclusion