Research On Forecast And Assessment Of Steam Turbine Rotor Life

With the development of modern industry, more and more people pay attentionto the steam turbine that is a typical power-generation equipment. In order to ensure itrun safely, reliably and economically, the service life of steam turbine is alwaysresearch focus. The steam turbine rotor is key component, but it is also vulnerablespot in steam power plant. The steam turbine rotor high-speed runs under the hightemperature and pressure, if it occurs failure, it will bring big disaster. Therefore, it isvery significant to study the life problem of steam turbine rotor.The domestic135MW steam turbine rotor is taken as research object in thispaper, combined with finite element technology, utilized finite element analysissoftware HyperMesh and ANSYS to calculate the temperature field and stress fieldunder cold-state startup. The result will be imported into the MSC.Fatigue to predictthe life of the steam turbine rotor and finish life assessment. The result has guidingsignificance for operation and design of steam turbine unit. The main research work isas follows:1) Analyzed the fatigue mechanism of the steam turbine rotor and the mainfactors on its fatigue life, and studied the calculation methods of the low-cycle fatiguelife and creep fatigue life.2) Determined cold startup scheme of steam turbine unit, drawn cold startupcurves. According to the pressure and temperature at everywhere in the process ofstartup, calculated the heat transfer coefficient based on thermodynamics theory andthen loaded it on the finite element model as boundary conditions.3) Created the steam turbine rotor3D model and reasonable simplified model bySolidWorks. Considering its centrifugal force, the blade is equivalent to the mass ring.To ensure the centrifugal force of it same as the blade, the thickness and density ofthe ring are modified. The grid model is completed and modified to requirement ofsolving by HyperMesh. Finally, the material properties and boundary conditions aredefined.4）The finite element model was input into ANSYS and the temperature field ofthe steam turbine rotor was solved. The stress field was finished with the temperature result based on the indirect coupling method. On the basis of the stress field,combining with the rotor material strain fatigue characteristic curve and loadspectrum, using the Neuber strain correction method on Miner linear fatiguecumulative damage theory, the rotor fatigue life was calculated, predicted andestimated.The life loss of the135MW steam turbine rotor was obtained during cold startupby research. And the safety service life of the steam turbine is estimated. It is verysignificant to calculate the life loss under other conditions and provides basis to drawlife management curve of the model unit.