On December 30, the world’s largest single capacity and largest size impact turbine runner was successfully welded and manufactured in Harbin Electric Group, and the world’s first single capacity 500 MW Zhala hydropower station impact turbine generator set runner was born, marking a major breakthrough in the development technology of China’s high head and large capacity impact hydropower unit, walking in the forefront of the world.
The turbine runner is the “heart” of the hydro-generator set of Zhala Hydropower Station, the backbone power station of the national “storage power transmission”, which provides the source power for the generator to emit 500 MW rated power. Under the unified organization of China Datang Group, the owner of the project, the energy conversion efficiency of the impact runner independently developed by Harbin Electric Group has reached the world advanced level. The runner adopts forging welding structure, consisting of 1 wheel hub forging and 21 bucket forgings, with a welded weight of 90.8 tons.
Impingement turbine is a hydraulic machine which uses pressure pipe to guide water flow and impingement runner for energy conversion. The design head of Zhala power Station is 671 meters, and the runner is one of the most important force and flow components that directly affect the efficiency of the unit. In the operation state of the unit, it is always subjected to a high frequency of dynamic pressure, which plays a crucial role in the stable operation and safety of the unit, and the welding manufacturing requirements are extremely strict.
As the world’s largest single capacity impact unit runner, its hub forging diameter of 4.7 meters, thickness of 1 meter, set a martensitic stainless steel largest forging world record; After processing, the maximum outside diameter of the runner is 6.23 meters and the maximum width is 1.34 meters, which is also the largest impact runner in the world. And due to material, shape, size and other reasons, welding, processing and other links of the manufacturing technology, are in the forefront of related fields, explore the manufacturing process, there are many risk factors and uncertainties, welding manufacturing requirements are extremely high, extremely difficult. In order to break through the welding difficulties of Zara 500 MW impact runner, Harbin Electric Motor Company has carried out technical research, adopted digital simulation technology, carried out research on die forging technology of large water bucket, and selected the “forging welding” manufacturing process route with excellent performance and efficiency; Through three-dimensional testing simulation calculation, the optimal welding parameters were explored and selected. The wheel hub and bucket made of martensitic stainless steel were welded together with high strength and toughness weld, which improved the impact toughness and fatigue resistance of the runner.
Through the welding and manufacturing of the Zara 500 MW impact unit wheel, the electric motor company of Harbin Electric Group has cracked the welding problems of ultra-large ultra-thick low-carbon martensitic stainless steel forgages, overcome the difficulties of high-efficiency and high-strength welding manufacturing of complex curved ultra-thick water bucket, mastered the key technology of ultra-high bonding strength surface strengthening manufacturing process, and promoted the major breakthrough in China’s electric power equipment manufacturing technology.It has set a new milestone in the process of high-quality development of China’s energy equipment manufacturing industry.