1000MW超超临界EC-BEST二次再热机组经济性分析

Economic Analysis of 1000 MW Ultra Supercritical EC-BEST Secondary Reheat Unit

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-ma- chine 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 k,l/（ 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.