Dam Operators Keep their Cool with Cold Spray Repairs
A better way to repair hydropower dam turbines
Better hydropower dam turbine repairs are just a cold spray away with PNNL’s research and development of cold spray technology for cavitation repair. Bonneville Power Administration funded a partnership between PNNL, the U.S. Army Research Laboratory, VRC, a premier equipment manufacturer, and MOOG, a cold spray repair contractor. These partners are working to develop a cold spray repair technique to dramatically improve the performance and service life of repaired turbines.
There are high direct costs associated with repair and replacement of cavitation damaged turbine blades. Not only are the costs high, but typical repair methods, such as arc welding, introduce new weaknesses to the repaired turbine blades. High heat input and melting associated with arc welding degrades properties in and around the repair. This results in increased frequency of repair and reduced turbine performance compared to a new turbine.
PNNL is researching an alternative to arc welding: cold spray repair. Cold spray works by shooting metal particles at supersonic velocities, or very high speeds. The impact energy created by these high speeds produces a solid state weld between the particle and the turbine surface. With this method, melting and material degradation does not occur and the turbine blade is left in its original shape. Even better, cold spray repair is capable of depositing materials with hardness and wear resistance that match or exceed that of turbine base metal—meaning cold spray repairs should produce superior performance of turbines.
Bonneville Power Administration, The U.S. Bureau of Reclamation, and Idaho Power are part of the project team. Input from engineers, project managers, and economists from these organizations is being used to guide technical development and create a foundation for commercialization of this technology. This includes performance benchmarking data, cost modeling tools, best practice documents, and a group of companies ready to provide equipment and tailor to needs of turbine repair.
PNNL researcher Ken Ross says, “This project is generating the performance data and cost modeling to quantify the improved performance and value proposition of cold spray repair for hydro turbines, and the initial results are promising.” The project team is confident that using cold spray repair will dramatically reduce the frequency of dam outages, resulting in less down time, and reduced service and maintenance costs for dams across the nation.
PNNL Research Team: Glenn Grant, John Lareau, and Ken Ross