Design And Analysis Of Main Feed Water Check Valve

The disc of check valve closes quickly under the reverse pressure of medium, then water hammer effect occurs and the abnormal pressure-rise caused by it will do great damage to pipeline. Micro-resistance and slow-closing check valve is to reduce the water hammer pressure by controlling the on/off speed of disc. At present, the program of micro-resistance and slow-closing check valve is to control the on/off time by adding controlling systems like auxiliary valve or hydraulic device. Adding auxiliary valve or modifying hydraulic device can really reduce the water hammer pressure, but the relatively complex structure of auxiliary valve dose increase the cost and price. Besides, water hammer can still occur if controlling system fails during operation, which results in pipeline break accident.The MFCV(main feed check valve) researched in the paper is installed in main feeding pipeline in nuclear auxiliary factory, which is used to prevent main feed backflow from the stem generator. The structure of check valve is self-trigger damping cavity plus balancing pipeline.In the paper, the limit hole dimension of MFCV damping cavity is determined tentatively according to design experience. Flow field values simulation under different flow quantities as disc opens fully is done by fluid analysis software FLUENT in the stableness of valve condition, thus the check valve inner flow field characteristics as well as the pressure difference in valve inlet/outlet and disc fluid acting force under different flow quantities are also received. By comparison with components like disc in valid gravity, pressure difference in inlet/outlet and corresponding conditions minimum fluid are gained. Additionally, valve damping values are gained by calculation. Water hammer effect calculation analysis is done on account of reverse flow due to broken pipeline, after which the medium fluid and water hammer pressure distributions by time of check valve in disc displacement, speed, and pipeline are reached, and the impact rules by damping coefficient are finally received, thus determining the closing time of valve. Check valve design is optimized by data analysis.In this paper, the impact rules by damping are received after MFCV design analysis, which offers effective theory basis for valve's practical manufacture, and plays an important role in corresponding product research and design.