en.Wedoany.com Reported - Recently, the world's largest hydroelectric pressure relief valve, independently developed by Harbin Electric Machinery Company Limited (HEMC) of Harbin Electric Group for the Tarbela 5th Extension Hydropower Project in Pakistan, successfully completed assembly and testing. This product set a world record with a nominal diameter of 3.5 meters. Multiple core technologies and innovative designs have reached internationally leading levels, marking a new peak for HEMC in the field of high-end hydropower equipment manufacturing.
The Tarbela Hydropower Station is Pakistan's largest and most important power supply base, accounting for one-third of the country's electricity generation. It is hailed as Pakistan's "Three Gorges Project". The 5th Extension Project of the station is a key project in China-Pakistan energy cooperation. HEMC is responsible for manufacturing all three 470-megawatt Francis turbine units for the project. The project is equipped with a total of four pressure relief valves, one being a main header valve and the other three corresponding to the three units. The pressure relief valves independently developed by HEMC for this project have a nominal diameter of 3.5 meters, a height of nearly 5 meters, and a weight of 92 tons. All four valves achieved "first-time qualification" in both processing, manufacturing, and assembly testing.
As a core safety device for the units, the pressure relief valve can respond rapidly under sudden operating conditions such as load rejection, excessively fast guide vane closure, pipeline rupture, abnormal pressure in the water diversion tunnel, and spiral casing overpressure. It can fully open for pressure relief within 8 seconds, accurately controlling the system pressure within a safe range, effectively protecting critical equipment like the water diversion tunnel, penstock, spiral casing, and turbine. It serves as the "safety guardian" ensuring the continuous and safe operation of the power station. The pressure relief valve for the Tarbela 5th Extension Project, independently developed by HEMC, features a fixed cone valve structure with a design pressure of 1.35 MPa. This is equivalent to a 135-meter water column acting vertically on each square centimeter, enabling it to adapt to the extreme high-head operating environment of the power station.
In terms of product design, this pressure relief valve has achieved several industry-first breakthroughs: adopting leading design concepts, it perfectly adapts to the special conditions of the Tarbela 5th Extension Project, which involves expansion while the existing station is operational; comprehensively optimizing and matching factors such as structural volume and jet trajectory to achieve optimal overall performance; overcoming challenges related to the stable long-stroke movement of the valve body and ultra-high assembly precision, ensuring the stability and reliability of the equipment under extreme conditions.
In terms of manufacturing processes, HEMC formed a dedicated R&D team to tackle a series of technical challenges arising from the valve's large nominal diameter, thin-walled components, and long stroke. Following a research approach of "problem orientation, theory first, process innovation, and test verification," the team precisely carried out technical research, achieving accurate and stable control over the dimensions of the super-large thin-walled parts and ensuring product quality.
In terms of production and manufacturing, the HEMC Hydropower Sub-factory, which took the lead in the processing, assembly, and testing of the pressure relief valves, collaborated closely with departments including the Product Design Department, Intelligent Manufacturing Process Department, Quality Inspection Department, and Control Equipment Division. They conducted in-depth technical briefings, meticulously analyzed the valve structure, drawings, and processes, anticipated problems, optimized processes, explored during production while summarizing experience, and promoted lean manufacturing, laying a solid foundation for the successful processing, assembly, and testing of the pressure relief valves.
The successful development of the pressure relief valve for the Tarbela 5th Extension Project is a significant achievement resulting from HEMC's commitment to independent innovation and deep cultivation in high-end hydropower equipment manufacturing. It demonstrates the core competitiveness of Chinese enterprises in the field of high-end hydropower equipment. A series of technological innovations and design concepts provide a Chinese solution and contribute Chinese wisdom to the safe and efficient operation of large-scale global power engineering projects.
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