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火电机组锅炉过热器蒸汽侧氧化膜在机组变工况时可能发生开裂甚至脱落,对受热面安全性构成严重威胁。以超临界锅炉T91过热器管材为研究对象,在考虑温度对金属和氧化膜热膨胀系数影响的基础上,采用多层空心圆柱体模型,对3种不同工况下机组停炉过程中蒸汽侧氧化膜的稳态应力进行数值计算和分析。通过对各应力分量以及Mises等效应力进行分析,阐明了蒸汽侧氧化膜2种可能的开裂模式,同时得出了停炉过程中变工况后的负荷相同时蒸汽温度过低或者变工况后的蒸汽温度一定而负荷过低都可能导致氧化膜因等效应力过大而开裂甚至脱落的结论。
The steam-side oxide film of the superheater of the thermal power unit may crack or even fall off when the unit is in the changing working condition, posing a serious threat to the safety of the heating surface. Taking T91 superheater tube of supercritical boiler as the research object, on the basis of considering the effect of temperature on the thermal expansion coefficient of metal and oxide film, the multi-layer hollow cylindrical model was used to analyze the steam oxidation in the three different operating conditions The steady state stress of the film is numerically calculated and analyzed. By analyzing the stress components and the Mises equivalent stress, two possible cracking modes of the steam-side oxide film are clarified. At the same time, the conclusion is drawn that if the steam temperature is too low or the working condition is changed under the same load After a certain temperature and the load is too low may lead to oxidation of the oxide film due to excessive stress cracking and even the conclusion of the collapse.