Sand erosion of Pelton turbine nozzles and buckets: A case study of Chilime Hydropower Plant

Erosion of hydro turbine components through sand laden river water is one of the biggest problems in the Himalayan region. This problem exists for all kinds of turbines. Apart from erosion of buckets, erosion was also observed in nozzle of the Pelton turbines due to sand particles and such problem was observed in 22 MW Chilime Hydropower Plant in Nepal. Detailed studies were conducted and erosion analysis was carried out in this case study. Sieve and mineral content analyses were systematically carried out and sediment load was calculated. By doing this, erosion rate and efficiency reduction were established using already known methodology and scenario for similar hydropower plants. The flow analysis through surface of needle was established by drawing flow net diagrams. This detrimental damage led to efficiency reduction of 1.21% consequently resulting in loss of power generation. A wear rate of 3.4 mm/year was estimated for the needle and the bucket after a systematic analysis.