Analysis of overflow operation of normal residual heat removal heat exchanger
For the problem that the shell side flow of normal residual heat removal heat exchanger exceeds the nominal flow rate due to flow distribution changes during the commissioning process of nuclear power plants,HTRI was used to analyze the thermal and flow induced vibration conditions at 120% flow rate.The maximum ratio of gap velocity to critical velocity was 0.25,which is less than 1.The max.vortex shedding amplitude to tube gap was 0.04,which is less than the 0.5.The above results indicate that there is no flow induced vibration risk at 120% flow rate.However,the ρν2 at the inlet of the shell side exceeded the limit requirements in the standard.Therefore,the finite element method was further used to perform mechanical analysis on the impingement plate and tie rods.The analysis results show that the structural design meets the strength requirements.In the actual engineering commissioning process,the equipment still can operate safely under the condition of 120% flow rate.Through comprehensive analysis,the flow rate on the shell side of the normal residual heat removal heat exchanger can meet the engineering requirements when it exceeds nominal design flow by 20%.