Surface and bulk modification techniques to mitigate silt erosion in hydro turbines: a review of techniques and parameters

Abstract

Silt erosion causes big efficiency and economic losses to hydro turbines and other industries involving the relative motion of the slurry/silt. This article reviews various techniques employed in the literature to mitigate the silt erosion. The main prominence is given to the latest technologies rather than the number of articles on the same technology. The available techniques are classified into two broad categories namely, surface modification techniques, and bulk material modification techniques; then reviewed systematically. The parameters (properties) which largely influence the material loss, for corresponding techniques, are also familiarized. In addition to this, how these parameters were improved and why these parameters enhanced the slurry erosion performance are discussed. Surface coating increases the surface hardness, is found to be the most addressed and most successful technique for the said purpose. The hardness of the substrate was found to be the most addressed property which can largely control the silt erosion.

Current insights into the factors affecting the erosion behaviour of iron alloy based coating material

“…Static parts include spiral casing, draught tubes, and other such items. There is the presence of silt, clay and sand particles in the fluid used in hydro turbine [7]. Desilting arrangements are installed in respective places to reduce /remove silt particles from flowing water and protect the turbine components.…”

“…In the Himalayan region, the erosion wear rate of the Pelton turbine was recorded as 3.4 mm/year for needles and buckets, which resulted in a decrease in hydro turbine efficiency by 1.21 % [7].…”