大型汽轮机组2次再热回热系统关键技术研究

Key technologies of double reheat &heat regeneration systems for large scale steam turbines

介绍了2次再热回热系统的结构形式及其系统所涉及的回热级数、外置蒸汽冷却器、再热点前加热器(HARP)、2次再热以及新型MC系统等关键技术。以超超临界800MW机组为例,对机组分别采用2次再热回热系统、MC系统及1次再热回热系统的经济性进行了比较。结果表明,机组2次再热与1次再热比较主蒸汽压力提高1.4MPa,主蒸汽温度降低5℃,机组热耗下降约226kJ/(kW·h),热效率提高约1.40百分点;机组MC系统与1次再热系统相比主蒸汽压力提高3.8MPa、主蒸汽温度降低5℃、机组热耗下降约235kJ/(kW·h)、热效率提高约1.45百分点,与2次再热回热系统相比系统效率提高非常小,其技术优势的体现依赖于高背压小汽轮机效率的提高。

The structure of the double reheat and heat regeneration system was presented.Key technologies including the number of regeneration stage,the external steam cooler,HARP,double reheat and the new MC system were discussed.Taking an ultra supercritical 800MW unit as the example,comparison between and among the unit applying the double reheat &heat regeneration system and that combined with MC system and that applying single reheat & heat regeneration system was performed.The results showed that,under the second reheat condition,the main steam pressure increased by 1.4MPa,while the main steam temperature dropped by 5℃,the unit heat consumption decreased by about 226kJ/(kW·h),and the heat efficiency rose by 1.4%.Compared with the single reheat system,for the MC system,the main steam pressure increased by3.8MPa,while the main steam temperature dropped by 5℃,the unit heat consumption decreased by about 235kJ/(kW·h),and the heat efficiency rose by about 1.45%.The system efficiency of the MC system increased little than that of the typical double reheat and heat regeneration system.However,the technical advantage of the MC system relies on further improvement of the high back pressure turbine.