Erosion wear studies on high concentration fly ash slurries

Erosion is an unavoidable phenomenon in the pipelines transporting bulk solids in both hydraulic and pneumatic conveying modes. Erosion wear depends on a number of factors like hardness of the material, size and shape of the solid particles, solid concentration, velocity of particles, impact angle of solids on the target material surface etc. Several investigators have made systematic studies to establish the functional dependence of erosion wear on various parameters. In the case of hydraulic conveying of the solids in slurry form, most of these studies are limited to low and medium solid concentrations only. But with the advent of new economical, environment friendly and water saving technology of solid conveying in the form of high concentration slurries (HCSD) the study of erosion wear at these concentrations becomes necessary. Hence, in the present study a modified pot tester capable of operating at high concentrations (C_w>60% by mass) has been designed and fabricated. Measurements have been made with fly ash slurries at various concentrations (in the range 50% to 70% by mass) and relative velocities (in the range 1 to 4 m/s). It is observed that the parametric dependence of erosion wear at high solid concentrations is at variance with that observed at lower concentrations. The erosion wear was found to have a stronger dependence on concentration as compared to relative velocity. Studies are also conducted to investigate the effect of variation of angle of impact on the erosion wear at a solid concentration of 65%( by mass) and it is noticed that erosion rate shows a maximum at an angle of 45°.