基于常规的1 000 MW二次再热机组的设计方案，提出了取消高、中压缸抽汽，采用多级小汽轮机抽汽的双机回热循环（EC-BEST）系统的设计方案，并且通过EES仿真软件对不同工况下ECBEST系统与常规二次再热系统的抽汽过热度、小汽轮机流量、循环效率和汽轮机热耗率等指标进行对比。结果表明：采用EC-BEST系统可以有效降低抽汽过热度，减少加热器不可逆损失；降低汽轮机热耗约30 kJ/（kW·h），折合煤耗约1.1 g/（kW·h）（按照锅炉效率94%）；循环效率提高0.3%。因此，EC-BEST二次再热具有更高的经济性，是未来大容量高参数二次再热机组发展的一个良好方案。

Based on the design scheme of the conventional 1 000 MW secondary reheat unit,a new design scheme of eliminating the high and medium pressure cylinder extractions and adopting the dual machine regenerative cycle (EC-BEST) system of multistage small steam turbine extraction is proposed.The ECBEST system and the conventional secondary reheat system are compared.The results show that the EC-BEST system can effectively reduce the superheat of the steam and reduce the irreversible loss of the heater.The heat loss of the turbine is about 30 kJ/（kW·h）,equivalent to coal consumption rate of 1.1 g/（kW·h）per boiler efficiency of 94%,and the recycling efficiency is increased by about 0.3%.Therefore,the EC-BEST secondary reheat has better economy,and the potential of becoming one of the directions for the reheat unit development.

TK26

国家自然科学基金（51176125）；上海市科委部分地方院校能力建设计划（16060502600）