PROBLEMS ENCOUNTERED DUE TO EROSION OF HYDRO TURBINE COMPONENTS WORKING IN HIGHLY SILTY ENVIRONMENTS - RD ACTIVITIES DIRECTED TOWARDS THEIR LIFE EXTENTION

摘要

Hydroelectric power stations in general and run-of-the river schemes in particular located in the northern states of India suffer from silt erosion in a big way. The rivers of these power stations originate from the Himalayas, which are geographically young and unstable. During the monsoon days (April-September), the streams carry heavy quantity of silt load. 98% of the silt particles of size 0.25 mm and smaller are of quartz with hardness of 7-8 on Moh's scale. It is not cost-effective to construct desilting arrangement to remove this size of silt from flowing water. The silt in high concentrations when passing through the machine causes extensive damages to all underwater components. Salal and Baira Siul power stations are the worst victims of silt erosion. The operation and maintenance of these power stations is indeed a tremendous task and calls for high degree of dedication and motivation on the part of maintenance staff in grappling with the silt related problems. The paper gives a brief account of the damages suffered by the turbine underwater components of Salal and Baira Siul power stations. Experience of NHPC in tackling the silt-related problems in these power stations is brought out. R&D activities being conducted in these power stations directed towards extending the service life of the underwater components by the application of different types of treatments and surface coatings and results thereof are reported.