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| Analysis on characteristics of flow in regulating valve and pipe system of water storage tank for boiler in ultra-supercritical power plants |
| HE Qingzhong, GUO Bin, DONG Xuelian, ZHANG Cheng, LIU Jia, CHEN Xuefeng |
| College of Mechanical Engineering, Sichuan University of Science & Engineering, Zigong, Sichuan 643000, China |
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Abstract In view of faced problems in flow structure design in the research and development of regulating valve of water storage tank for boiler in ultra-supercritical power plants in China, combining the cavitation erosion of valve plate in the previously designed regulating valve in a specific plant, a series of numerical simulations of two-phase cavitating flow field in a regulating valve and pipe system are carried out by using CFD code in Fluent. In the simulations, the RNG k-ε. turbulence model and full cavitation model are used to validate fluid flow structure and to optimize the valve structure, especially, a cone valve and its pipe system are paid attention. The results show that cavitation occurs seriously in the throat of the original cone valve under design condition due to the very narrow opening. Particularly, the vapour volume fraction is above 90% and the flow velocity is as high as 143 m/s, leading to damage to the valve plate by cavitation eventually. To eliminate the cavitation, a new type of valve structure is put forward. The results show that the vapour volume fraction is reduced by 21.6% and the fluid velocity is decreased by 80% near the throat, suggesting the cavitation phenomenon has been suppressed to some extend and the pipe system is capable of safe operation. The simulated results exhibit the flow field distribution in the valve and pipe system more clearly, and provide theoretical references for the design and optimization of regulating valves, as well as promote the nationalization of this kind of valve.
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Received: 26 November 2015
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