A view of the inlet spherical valve for Unit 1 at Zhala Hydropower Station. Photo: Screenshot from Dongfang Electric Corporation's Wechat account

The inlet spherical valve of Unit 1 at Datang Zhala Hydropower Station - also the world's first set of 500 MW impulse hydropower units - has successfully passed the hydrostatic pressure test in Southwest China's Xizang Autonomous Region in recent days, with sealing performance under all operating conditions meeting design requirements. 

This milestone marks the completion of the on-site assembly and testing of the hydropower station's first giant inlet spherical valve, according to a report by the Securities Times on Sunday. 

The project is also the first approved megawatt-level hydropower project in Xizang and a key power source for China's national-level clean energy demonstration base integrating hydropower, wind, and solar resources in southeastern Xizang region, according to media reports. 

Datang Zhala Hydropower Station is equipped with two 500 MW impulse hydropower units (Pelton turbines), each with a single-unit capacity of 500 megawatts, featuring high head, large capacity, and high altitude, according to a post seen on Dongfang Electric Corporation's Wechat account on Sunday. The company is responsible for the research, development, and supply of one of the complete units.

The project has been included in the National Energy Administration's list of the first major technical equipment projects in the energy sector. It is not only China's only hydropower project capable of conducting research, development, and application demonstration for 500 MW-class high-head, large-capacity impulse units, but also currently the world's most technically challenging impulse hydropower project under construction, said the post.

The inlet spherical valve for Unit 1 at Zhala Hydropower Station has a diameter of 2.9 meters and a design pressure of 9 mega pascal. It consists of multiple core components, including the large valve body, small valve body, valve disc, and valve shaft. The total assembled weight of the spherical valve body exceeds 300 tons.

The comprehensive difficulty of the valve's design, manufacturing, and installation has reached a new height in the industry for the development of main inlet spherical valves, said the post, while highlighting that the completion of the test will "propel China's research and development capabilities for core components of high-head, large-capacity impulse hydropower units to a new level."

Unlike conventional assembly carried out inside enclosed workshops, the entire assembly of this spherical valve was performed in an open-air yard. This process faced numerous practical challenges, such as limited working space, restricted hoisting areas, and complex and variable outdoor environmental conditions, the company post said.

Global Times