本文针对1000MW机组热力系统抽汽过热度偏高的问题,采用外置式蒸汽冷却器系统来吸收抽汽过热度部分的热量，提高给水温度，减少不可逆损失，提高机组效率。研究比较了变负荷条件下的1000MW机组常规系统和外置式蒸汽冷却器系统的热力学性能，对常规系统和外置式蒸汽冷却器系统分别进行了?分析，揭示了外置式蒸汽冷却器系统节能效果的热力学原因。研究结果表明:外置式蒸汽冷却器系统的节能效果随着负荷降低而增加。外置式蒸汽冷却器系统中锅炉?损系数和回热加热器?损系数都低于常规系统。在两种热力系统中，回热加热器的?损系数都随着负荷的降低而降低，锅炉的?损系数都随着负荷的降低而增大。

The superheat degree of extracted steam in the regenerative system of 1000MW units is higher. In order to solve the problem, this studyselected a typical 1000MW ultra-supercritical unit as reference system in this study and presented a regenerative system with an outer steam cooler to utilize the superheat of extracted steam and improve the feed water temperature. As a result, the irreversible exergy destruction will be reduced, and the power generation efficiency will be improved. Comparative study of energy saving effect of the reference system and the outer steam cooler system under variable load operation conditions are conducted. Besides, exergy analysis of the two systems is conducted to reveal the energy saving effect of outer steam cooler system. The results show that, the energy saving effect of the outer steam cooler is reduced as the load decreases.The exergy destruction co-efficient of the boiler and the regenerative heaters in the outer steam cooler system is lower than those of thereference system under all operation conditions. Both in the two systems, the exergy destruction co-efficient of the regenerative heater is reduced as the load decreases.However, the exergy destruction co-efficient of the boiler is increased as the load decreases.

国家自然科学基金项目（面上项目，重点项目，重大项目）