PERFORMANCE EVALUATION OF DESILTING TANK

Abstract

The global energy demand is on the rise, particularly in developing countries. Small hydropower (SHP) generation has gained significant importance due to its distinct advantages, including easy allocation, high reliability, no fuel costs, and low maintenance. Additionally, SHP is an environmentally friendly and renewable energy source, free from pollution and depletion. Run-of-River hydropower plants are commonly installed in steep mountainous streams, which are prone to high soil erosion. Seasonal floods, especially in tropical and monsoon regions, result in substantial sediment yield from these catchments, leading to high sediment concentrations in the streams. Therefore, managing sediments entering the headrace channel is crucial in Run-of-River hydropower schemes to minimize erosion of turbines and other water-exposed components. Desilting tanks, constructed in series with the headrace canal, play a vital role in this regard. The design dimensions of the desilting tank significantly influence its efficiency in trapping sand and sediment. Various methods and devices exist for sediment removal, and their suitability depends on the sediment volume and characteristics, as well as the desired sequence of sediment removal. Among these methods, settling basins are widely employed in SHP sites. Recently, a new type of desilting basin, called a vortex settling basin, has been developed to enhance the trap efficiency of settling basins. The present dissertation deals with the performance evaluation of desilting tank. Under this study, desilting tanks are designed and checked with the existing site dimensions, design, operation and maintenance issues are discussed to evaluate the performance. Theoretical efficiency is calculated by various investigators using their empirical relationships. Power loss generation data is analysed to study the effect of silt accumulation in desilting tank leading to a decrease in efficiency and hence generation loss of the hydropower plant. An attempt is made to standardize the design, so as to propose a fully efficient desilting tank.