The influence of recirculating flue gas extraction positions on the system's operation was analyzed for ultra-supercritical double-reheat units. From the aspects of operation performances of air pre-heater, electrostatic precipitator, induced draft fan and flue gas recirculation fan, the characteristics of different flue gas extraction positions were investigated, the advantages and disadvantages of two extraction schemes and the key technical problems need to be solved were obtained. On this basis, technical measures were proposed to maintain the system safety and steady operation. Moreover, the two circulating flue gas extraction schemes (from the entrance duct of the air preheater, and from the outlet duct of induced draft fan) were applied in the circulating flue gas system of Huaneng Laiwu Power Plant and Anyuan Power Plant. The operation results show that, after applying these two schemes, the units achieved stable and safe operation, indicating the two technical schemes both have potential of promotion.%针对超超临界二次再热机组锅炉烟气再循环系统再循环烟气的不同抽取位置对系统的影响特性进行了对比分析,分别从空气预热器(空预器)、电除尘器、引风机、再循环风机的运行特性方面分析了不同抽取方案的特点,得到从空预器入口烟道和引风机出口烟道2种再循环烟气抽取位置方案的优缺点及需解决的关键技术问题,提出了2种方案下应采取的技术措施,并在华能莱芜发电有限公司、安源发电有限责任公司超超临界二次再热机组烟气再循环系统中得以实施.运行结果显示,2种方案均实现稳定、安全运行,有推广潜力.
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