二次再热机组热力系统的定量分析方法

Thermo-Economics Analysis Method of Thermal System for Power Unit with Double Reheat

针对超临界二次再热机组的二级再热器,高、低压加热器采用回热抽汽均设外置蒸汽冷却器的方式进行过热度跨级利用的特点,利用等效热降理论,经过严格的理论分析和数学推导得出了二次再热机组抽汽等效热降、抽汽效率和抽汽吸热量变化的通用计算模型,给出了此类机组热力系统的经济性定量分析法则,形成了一套完整的经济性定量诊断计算模型.利用该模型只需要3个计算公式即可以方便、快捷、准确地计算出当热力系统发生局部调整和变化时机组的经济性指标的变化,并为此类机组热力系统的经济性定量分析提供了一种简捷、准确的方法,拓展了等效热降理论.通过实例计算验证了本文计算模型的可行性和准确性.

Based on the equivalent enthalpy drop theory, the mathematical models for calculating equivalent enthalpy drop, efficiency and heat absorption of the regeneration extraction steam were established according to the characteristics of thermal systems of supercritical pressure power units. Then the rules for analyzing the economy of thermal system changes were presented. The correctness was verified by an example. The result shows that the proposed economy analysis method is easy to be used for calculating the index change of supercritical pressure power units.