Study On Thermal Stress Calculation And Start-up Optimization For Steam Turbine Rotor Of Combined Cycle Based On APDL

Gas-steam combined cycle power plant needs to participate in peak load with two-shift operation, and the steam turbine of the unit was designed as single shaft, no reheat, no steam extraction, combined cylinder with high pressure and low pressure, and the rated power was 105MW. Based on the Finite Element Method (FEM), taking the steam turbine rotor of the unit as study object and using ANSYS software, after some reasonable assumptions and simplification, a 2-D axisymmetric model was built. Then, mesh was generated by manual operations, and a finite element model of rotor was obtained by local mesh refinement on fillets. The steam temperature and pressure of every stage and every part in start-up process was obtained by calculating the steam parameter when power was 95MW. And then, according to the calculation formulas for steam properties provided by IAPWS and calculation formulas for heat transfer coefficient provide by former soviet, heat transfer coefficient of rotor face and steam in every stage and every part. At last, using thermal-structure sequential coupling method, the temperature and MISES stress field of rotor in processes of start-up was obtained, and based on the results of calculating, he low cycle fatigue life was calculated.The whole process of calculation completely used in APDL programming, for different process of start-up, the only changes ware editing CSV files storing steam parameter and initial temperature of rotor, after that, the temperature and stress field of different processes ware obtained. And it greatly simplified operation, enhanced reproducibility for further automation of playing a solid foundation.According to the results calculated by this paper, the steam turbine operation rules used in actual operation ware modified. It can save 100 minutes in every start-up through decreasing the metal temperature in control stage from 390℃to 350℃. Assuming that the plant start in this curve 150 times every year, and the generation price is￥1.02, the plant can increase economic benefits of￥17 034 500 every year.