Hydropower - the forgotten giant
According to the International Hydropower Association (IHA) more than half of the world's existing hydropower capacity is expected to be due for modernization by 2030 (Ref. 1) and the International Energy Agency (IEA) states that globally, around half of hydropower’s economically viable potential is untapped (Ref. 2). Hydropower is a proven technology and currently the largest source of renewable energy, but also hydropower brings the flexibility we need in the power sector with storage capacities. Deloro is committed to increase the productivity of hydropower technologies by providing wear and corrosion protection for critical components in hydropower plants.
Critical components in hydropower plants must withstand simultaneous wearing mechanisms such as slurry erosion wear, hydro abrasion, and cavitation. Therefore, the turbines are subject to efficiency losses. The good news is that the lifetime of hydropower components can be increased significantly with appropriate wear resistant materials such as Stellite™.
One of the decisive factors determining the type of wear mechanisms is the angle between the particle-laden flow and the component surface. At low angles, the loss of material is caused by the removal of micro-chips or the plowing up of the surface with the removal of the raised material parts. As the angle increases, the wear pattern shifts towards surface deformation and disruption. Due to the erosive attack at low angles, soft ductile materials are more strongly attacked, while hard and brittle materials are more damaged at high flow angles. (Ref. 4)
Since there are often different angles of attack in flow systems and machines, the behavior of wear protection layers under these different conditions must be considered and appropriate material must be chosen.
Deloro Wear Solutions offers a wide range of solutions for different kind of hydropower turbines such as Pelton, Francis and Kaplan and can adapt the alloys according to the individual conditions in which hydropower plants are operating, i.e. particle load, flow angle and speed, etc.
Injection needles and seats for Pelton Turbines must operate in highly abrasive and erosive environment caused by a mixture of water, sand and stones. Especially, hydropower plants driven by glacial water are attacked by suspended solids. Sand cast Stellite™ and/or HVOF hardfaced needles and seats perform significantly better in surroundings with high degree of erosion compared to uncoated steel substrate.
Sand seal rings for guide vanes are exposed to currents composed of water, sand and stones which lead to hydro abrasion and slurry erosion wear at critical parts. Machined Stellite™ centrifugal castings have significantly longer lifetime compared to rings made of stainless steel or Cu-Al bronze.
Wear segments for outer contour of turbine wings must withstand extreme cavitation. With Stellite™ Laser or PTA coating on 1.4571 base material, parts have significantly better properties in surroundings with a high degree of cavitation compared to uncoated segments.
Wear parts for all types of hydro turbines can be newly produced according to specification of hydro power plant operators and worn-out parts can be refurbished with Deloro’s capabilities. Additionally, Deloro provides welding materials for turbine repair jobs executed by OEM’s or specialized service providers.
Curious how you can increase the productivity of your hydropower plant through wear protection of critical components? Do not hesitate to talk about your challenge with us.
1. IHA - International Hydropower Association
2. IEA (2021), Hydropower Special Market Report, IEA, Paris https://www.iea.org/reports/hydropower-special-market-report
3. Ziyi Yang et al, (2022) Microstructure, hardness and slurry erosion-wear behaviors of high-speed laser cladding Stellite 6 coatings prepared by the inside-beam powder feeding method, Journal of Material Research and Technology, 19, p 2596-2610
4. Prof. Dr.-Ing. V. Wessling et al, Verschleißschutzsysteme gegen hydroabrasive Belastungen, TU Clausthal-Zellerfeld
5. Ekanger, Jarle Vikor (2011) Master of Science in Energy and Environment Morphing skins to improve local flow behavior in a hydroturbine context Adaptive overflater for forbedring av lokal strømning i vannturbinsammenheng