Development of a sediment resistive Francis runner

There are many hydro power plants that are affected by large amounts of sediments during the rainy/ monsoon season. Himalaya in Asia and Andes in South America are examples of large regions where there are hydro turbines which experience heavy sediment erosion every year. Turbine manufacturers have been developing new materials and coatings that can be used in turbines. The most successful solution seems to be wolfram based coatings. In Francis turbines, the coating has been applied to the cover, guide vanes and some parts of the runner. The coating of the whole Francis runner has been difficult because there is simply not room for the equipment used to apply the coating to the surface. DynaVec have developed a new production method that allows them to apply the coating to the whole surface of the runner vanes. This has been applied to a runner at Cahua Power Plant in Peru. The Power Plant has two Francis turbines where each has a power output of 23 MW. The head is 215 meter and the sediment erosion in the turbines is severe. The turbines are operated at maximum 5000 ppm sediment concentration and the sediment the passes the turbine has about 30% quartz and 30% feldspar content. This means that the turbine has a maximum sediment load of 50 kg/s and 60% of this is minerals that are harder than the base material of the turbine.