Hydro-abrasive erosion in Pelton buckets: Classification and field study

Abstract

In fragile mountainous regions, hydropower plant components face severe hydro-abrasive erosion, resulting in reduced efficiency, frequent interruptions in power generation and downtime during maintenance. In this study, the hydro-abrasive erosion is classified and measurement methodology is proposed for various erosion patterns in Pelton buckets. In Pelton buckets of a high head hydropower plant located in the Himalayas in India, the amount, pattern and depth of erosion were measured during the study period May-October 2015. The size, shape and concentration of the suspended sediment passing through the turbines were obtained from manual samples and with an online multi-frequency acoustic instrument.In uncoated buckets, the average reduction of the splitter height and the abrasion in the cut-out portion were 3% and 5% of the bucket width respectively, whereas the maximum erosion depth of ripples in the curved zone was 1.5%. 73% of suspended sediment consisted of silt particles with median grain size (d50) between 20 and 40µm. With coefficient of variation 75%, 32% and 1% for concentration, d50 and shape respectively, 12,540t of suspended sediment passed through each turbine unit during 3180h of operation. This study seeks to facilitate the measurement of hydro-abrasive erosion in Pelton turbines and suspended sediment parameters.