| Popis: |
Hydro-abrasive erosion in turbines of hydropower plants (HPPs) at sediment-laden rivers is still a concern despite the application of hard-coatings. To further investigate the problem and support HPP operators to better cope with the fine sediment load and its consequences, a long-term research study was conducted at the high-head run-of-river HPP Fieschertal in the Swiss Alps. From 2012 to 2020, the sediment load, erosion and efficiency differences of the two 32 MW-Pelton turbines of the HPP were measured. To do so, a real-time sediment monitoring system was installed and procedures to monitor the efficiency of the turbines were implemented. In parallel, the costs of the refurbishment and replacement of the main turbine parts were tracked. The nine years of detailed data were used to optimize the HPP operation and the turbine maintenance. A key element of this optimization is to shut down the HPP in periods of exceptionally high suspended sediment concentrations (SSC). The threshold value above which the operation of this HPP becomes unprofitable, the so-called shutdown-SSC, was determined as 15 g/l (15 000 ppm). For reliable real-time measurements up to such high SSC, a Coriolis Flow and Density Meter (CFDM) has been installed at the intake in addition to a turbidimeter whose measuring range is limited to 6 g/l. The findings of this project, such as a combination of instruments for real-time SSC measurements and the procedure to determine the shutdown-SSC, can be applied to other medium- and high-head run-of-river HPPs at sediment laden waters to improve their economic and energetic efficiency. |
