ECONOMIC ANALYSIS OF SILT EROSION IN HYDRO TURBINES

Abstract

Hydro turbine in a hydro power plant is one of the most important component. In case hydro turbine is not functioning properly or is out of order for maintenance or otherwise, plant suffers a huge loss of power generation and revenue. The function of turbine also affects the efficiency which may be reduced due to silt erosion/cavitation. Even one percent loss in efficiency of hydro turbine leads to perpetual loss of power and revenue. Silt erosion in hydro turbines may be reduced to an economically acceptable level. Many investigators have studied the process of silt erosion in hydro turbines through experimental and analytical studies. Some of the investigators have reported that even design changes in the turbine components and using different materials and coatings to the turbine blades, the improvement in most cases are not significant. Hence, further experimental and theoretical studies are required for studying the effect of hydro abrasive erosion under different flow conditions. In present study, the correlations available for estimating the silt erosion in different types of turbines are thoroughly studied. The existing co relations which can be used. satisfactorily to determine the extent of erosion within the permissible range are verified using different values of correlation parameters. Based on these correlations, the trend of metal Ioss in turbines due to silt erosion has been obtained. Using other empirical equations, the power loss due to drop of efficiency under different working conditions may be a valuable tool in assessing a new runner design (to determine the lifetime operating cost). Cost analysis is carried out for the turbines affected due to erosion using cost of generation, cost of repair, maintenance cost and cost of mitigation which have been obtained from various turbine manufacturers. A methodology is evolved to analyze the economics of hydro turbines under such conditions. Such analysis shall be helpful for the turbine manufacturers and plant owners for comparative analysis to decide whether they should go for preventive measures for silt erosion in turbines or for maintenance of turbines.