OBSERVATIONS ON AND THE MODELING OF EROSIVE WEAR OF A LONG-RADIUS PNEUMATIC CONVEYOR BEND

This paper describes the results of an experimental investigation of t he erosive wear, and puncture, of a long-radius bend in a pneumatic co nveyor when used to convey abrasive particles. Measurements were taken of (a) the local air pressure in the pipe bore (used to obtain values of the local superficial air velocity), (b) the mass of abrasive part icles flowing through the pipe with time, (c) the reduction in the thi ckness of the bend wall and (d) the particle concentration distributio n using a simple optical obscuration technique. From analysis of the r esults it was deduced that an accumulation of the particles against th e outside bend wall, and the shape of the pipe bore itself, caused the particles to rebound back towards the pipe bore centre-line after pri mary impact. This behaviour caused an intensification of particle impa cts in the region where secondary impacts predominate, and this is whe re puncture was found to occur. A simple empirical model is proposed f or the prediction of the bend wear life. This is based upon an analogy between the particle dynamics in the bend and the optical aberration of a cylindrical mirror of similar dimensions to the pipe bore.