非常规服役超临界锅炉的微纳尺度腐蚀动力学模型建立及应用

Deep and frequent peak shaving supercritical/ultra-supercritical coal-fired boilers of thermal power units will serve in non-conventional conditions with frequent temperature changes and large changes. However, the traditional corrosion kinetic model relies on continuous exposure time at a constant temperature, which is challenging to meet the corrosion prediction and safety assessment of boilers in non-conventional service. According to the fundamental atomic/molecular scale process of corrosion of boiler high-temperature heating tube (in supercritical water environments), this paper proposes a new micro-nano scale kinetic model construction method for the prediction of corrosion in non-conventional conditions and the multi-scale application of the model in macro-corrosion data fitting and micro-scale corrosion process analysis. On this basis, a mechanistic corrosion kinetic model with clear microscopic processes and physical meaning for T92 steel was obtained. And a micro-nano scale oxide film growth rate model with temperature and film thickness as independent variables was developed. Finally, these micro-nano scale kinetic models were employed for the corrosion prediction of boiler tubes with known corrosion levels or/and at frequent variable load (non-constant temperature). It is of tremendous importance for evaluating the safety of large coal-fired boilers in non-conventional service.