| As large capacity turbine taking peak load more and more frequent, a lot of problem appears, such as the thermal stress and fatigue life expenditure,deformation and economical. So the research on thermal stress monitoring and peak load operating optimization become necessary.Some subjects on the thermal stress monitoring and peak load operating optimization of large capacity turbine have been studied in this thesis.The method is discussed to give out the accurate boundary condition and primary conditions in finite element analyze. The influence of primary stress and strain in the rotor on the thermal stress and fatigue 1ife expenditure is then analyzed. It is found that the stress will be influenced but the fatigue life expenditure will not.We calculate the effect of materiel characteristic change with temperature in the calculating of thermal stress and strain. A new method is given to calculate the fatigue life expenditure that occurs in vary temperature.A new ANN method is given to raise the precision of finite di fference method, which is more quick than finite element method and more exactitude than finite difference method.Three predict model is given, including a model to figure the steam temperature behind the regulative stage while considering the cooling of metal to the steam, a model to simulate the difference expand of HP cylinder, and an influence function model to quantify the proffer of each operating action to the finial stress peak.The problem of best temperature mismatch in the warm start-up is discussed, and influence function model is used to analyze this problem in theory. Small range negative temperature mismatch is found to be the best. It can make the start-up more safe and more economic. Then, finite elements analyze results for this problem in different power unit are given.At last, the generation cost is analyzed. A new idea to calculate the generation cost including both the fuel cost and the equipment cost is given. |
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