Common Issues Found During Inspections of Turbine Runners in Pumped Hydro Storage Systems
During inspections of turbine runners in pumped hydro storage systems, several key issues are commonly encountered. These can be categorized into material defects, operational issues, and environmental factors.
1. Material Defects
- Cavitation Pitting: This occurs due to the formation of vapor bubbles near the turbine runner surfaces, which collapse and create pits, leading to metal erosion and structural weakening.
- Corrosion: Especially in environments with high oxygen levels or dissolved solids, corrosion can damage turbine runners, particularly at interfaces between different materials like carbon steel and stainless steel.
- Galvanic Corrosion: Occurs when two dissimilar metals are in contact, potentially exacerbated by cavitation pitting or defects in weld overlays.
2. Operational Issues
- Fatigue Failure: Cyclic loading and stress from frequent start-ups and shutdowns can cause fatigue damage to runner blades and other components.
- Thermal Stress: High temperatures during welding can introduce defects in metal components, affecting their durability.
- Vibration and Dynamic Loads: Sudden changes in operation, such as rapid shutdowns, can cause vibrations that lead to structural failures in turbine components.
3. Environmental Factors
- Hydro-Abrasion and Erosion: Sediment-laden water can cause significant wear on turbine components, leading to mechanical failures.
- Sand and Silt Erosion: These particulates can erode surfaces of hydraulic components, reducing plant efficiency and potentially causing shutdowns.
Inspection and Maintenance Strategies
- Regular inspections are crucial to identify early signs of damage. Utilizing sensors and control devices can help monitor turbine conditions when visual inspections are not feasible.
- Maintenance platforms and proper lighting are necessary for thorough inspections of the runner, draft tube, and other critical areas.
- Consulting with the turbine manufacturer can provide valuable insights into addressing specific issues encountered during inspections.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-common-issues-found-during-inspections-of-turbine-runners-in-pumped-hydro-storage-systems/
