根据水和水蒸气的热力性质,将超临界直流锅炉蒸发受热面分为过冷水段、过渡段和过热段,通过机理分析和模型简化,采用集总参数法建立蒸发受热面、分离器和过热器的模型,利用锅炉结构设计数据计算不同负荷下锅炉的蓄热系数,并对某1 000 MW超临界机组锅炉进行实例计算.结果表明:当锅炉在亚临界状态下运行时,随着压力的变化,水冷壁内工质蓄热的变化量大于超临界状态下的变化量；金属的蓄热远大于工质的蓄热,过热器的蓄热占整个锅炉蓄热的70％左右；超临界锅炉的蓄能系数随着压力的升高而减小.%By dividing the evaporating surface of supercritical once-through boiler into cold-water, density-change and overheat-steam three sections according to thermal properties of water and steam, a lumped-parameter model was built up for the evaporating surface, separator and superheater through mechanism a-nalysis and model simplification, with which the heat storage coefficient of boiler was calculated under different loading conditions based on design data of boiler structure. Application results to a 1 000 MW supercritical unit show that the heat storage of working medium in boiler water wall varies more greatly along with the pressure at subcritical pressure than at supercritical pressure; the heat storage capacity of metal material is much higher than working medium; the superheater collects about 70% heat of the whole boiler; the heat storage coefficient of supercritical boiler reduces with rising pressure.
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