| With the development of our country's economy, the users of electricity consumption are increasing while a number of small and medium-sized unit is being out of service, more and more large steam turbine units are running on peak load. With frequent starting and stopping or variable load non-steady-state operating, temperature of steam turbine rotor will change sharply, which leads to a large temperature gradient and then produces larger alternating thermal stress, thus results to low cycle fatigue loss. At the same time, rotor runs in constant high temperature for a long term, materials creep phenomena will occur. So that it causes loss of high temperature creep. The interaction of Low-cycle fatigue and creep make rotor crack. Gradually extended cracks will make rotor fracture and will seriously affect security running of unit. So it is greatly significant for safe and economical operation of power plant equipment to in-depth study on the life loss of unit.The first part of this paper described the background, significance of subject, and the research status of domestic and foreign countries. The second part described the theoretical basis of a dimensional recursive methods and finite element algorithm. The third part made a660MW unit's ultra-supercritical steam turbine rotors to be research object, using ANSYS software to established model, mesh and set boundary condition. The forth part used simulation to calculate the temperature field and stress field of the cold start-up, warm start-up, hot start-up and normal stop, and calculated the equivalent creep stress field of stable operation. Besides the paper used unsymmetrical cycled method and lasting strength curves to calculate dangerous section's loss of low cycle fatigue and high temperature creep, and then calculated the total loss of high and medium pressure steam turbine rotor in a year time under the interaction of creep and low cycle fatigue. At last it gave suggestions of steam turbine safe and economic operation. |
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