Abstract
Turbine wear caused by hydro-abrasion due to suspended sediment in the turbine water has a negative impact on the power production and revenue of hydropower schemes. Efficiency of desanding facilities that reduce suspended sediment load ahead of turbines is key to limiting hydro-abrasion. Existing facilities built according to common design approaches often show lack of performance, in particular under non-ideal site-specific inlet and outlet conditions. Consequently, a new design concept that allows for the optimized design of desanding facilities at hydropower schemes has been developed based on prototype field measurements and CFD modeling. The effects of facility layout and components, such as tranquilizing racks, transition zone and outflow weir and related design parameters on the flow field and involved particle settling have been investigated in a comprehensive numerical model study. Hence, length adjustment terms were deduced from resulting changes in trapping efficiency, which allow for the estimation of the required basin length and an optimized facility layout. Compared to design approaches considering linear settling trajectories of sediment particles, the proposed procedure leads to longer settling basins in general and thus to increased trapping efficiencies of desanding facilities. Furthermore, the findings about the effect of specific facility components may allow for the optimisation of existing desanding facilities in an economical way.
Highlights
Received: 30 December 2021Suspended mineral sediments in the turbine water may damage components of hydropower schemes
Flow velocities, suspended sediment concentrations (SSC) and particle size distributions (PSD) were simultaneously recorded at three different times t1 (4 pm), t2 (6:15 pm) and t3 (8:15 pm), while the mean discharge was nearly constant at 2.2 m3 /s
The horizontal expansion can be realized as a sudden sharp-edged widening, which results in a simpler geometry, leading to reduced construction costs. Using installations such as tranquilizing racks or flow deflectors is strongly recommended to improve trapping efficiency, especially in situations with asymmetric and/or supercritical approach flow, provided floating debris can be trapped at the water intake to avoid blocking at the rack or deflector structures
Summary
Received: 30 December 2021Suspended mineral sediments in the turbine water may damage components of hydropower schemes. Turbines used in medium- and high-head configurations can be subject to hydro-abrasion. This may result in wear, which leads to a considerable efficiency reduction [1] and has substantial drawbacks, e.g., frequent operational interruptions in overhauling or replacing turbines and reduced energy production, each accompanied by financial loss. Economic and reliable desanding facility operation has become increasingly important with regard to efficient hydropower production as a renewable energy source. This is a challenge in Europe because meltdown water discharge and sediment yield from glaciated catchments will increase due to glacial retreat [2]. The flow is retarded, allowing sediment particles to sink and settle on the basin bed from where they are intermittently or continuously flushed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
