MA Chao xin, XUE Zhong yi, HUANG Wen hao, ZHANG Long zhou

 

(China Nuclear Power Engineering Co., Ltd., Shenzhen 518124, China)

 

 

Abstract: Aiming at the pressure fluctuation of hot water pump outlet at a specific temperature of hot water production and distribution system in a nuclear power plant, the NPSHA of the hot water pump was calculated and compared with theoretical value, pump vibration value was measured on site and compared with national standard. Based on the theory of gas liquid two phase flow, the pipeline layout was studied and the air solubility of the system under different temperature was analyzed. Combined with the flow velocity calculation, vent valve was installed at the high point with low flow velocity of the system pipeline. Results show that pressure fluctuation is caused by the gas liquid two phase flow pattern transformation, the solubility of air under different water temperature changes caused this phenomenon only appear under a certain temperature, this problem can be resolved by installing vent valve in the appropriate position.

 

Key words: pressure fluctuation; net positive suction head available(NPSHA); evolved gas; gas liquid two phase flow