Research On The On-line Monitoring Of Thermal Stress For Steam Turbine Rotor

The thermal stress is an important factor to restrict the life of the rotor,which determines the life of steam turbines.Therefore,it is very important for the life management of the unit to achieve on-line monitoring of thermal stress for steam turbine rotor.In this paper, the 2D finite model of governing stage for 600 MW ultra-supercritical steam turbine rotor was established by finite element software ANSYS,and the temperature field and stress field were simulated simultaneously. According to the results,the stress concentration appeared on the impeller root transition section of rotor governing stage.Then,the mathematical model for temperature field and stress field of steam turbine rotor were established by the method of mathematical analysis based on the heat transfer principle.in order to verify the accuracy of the established rotor thermal stress model.The numerical solution of the thermal stress in the impeller root for the rotor with the same condition was calculated by using MATLAB,two kinds of calculation methods and results were compared,and the calculated results of two methods have a good consistency.The stress concentration part on rotor governing stage was selected as the monitoring point,the operation parameters for the thermal stress monitoring point were collected and processed by using the sensor and PLC.The configuration software was used to write the action script program in the computer based on the established mathematical model of rotor thermal stress,and the variable physical property of rotor material was solved by Newton interpolation method.Finally,a set of on-line monitoring system,depended on the thermal stress as the monitoring index,for turbine rotor thermal stress based on PLC and configuration software was developed.the system hardware equipment were built and the off-line simulation was designed.The on-line monitoring system for thermal stress of steam turbine rotor was very good to achieve the real-time monitoring of the thermal stress for the turbine rotor,the function of automatic alarm and printing historical data,which provided the guidance for the optimization and safety operation of the unit,and extended the service life for the unit.