锅炉烟气再循环技术不仅能够减少煤粉燃烧过程中生成的NOx,还能起到调节再热蒸汽温度的作用,是锅炉低NOx燃烧和调节再热汽温的主要手段之一,国内外对于烟气再循环技术开展了众多研究。但是,目前国内的研究主要集中在再循环烟气量对锅炉燃烧和换热的影响,仍然缺少大型燃煤发电机组中多种再循环烟气引入位置的详细对比研究与分析。本研究以某1000MW超超临界二次再热四角切圆塔式炉为研究对象,对其建立三维模型并进行燃烧数值模拟,探究再循环烟气引入位置对锅炉燃烧、NOx生成特性、屏底烟温和炉膛换热的影响。结果表明:在所选取的四种不同再循环烟气引入位置中,将再循环烟气与一次风混合后引入,强化了一次风与二次风之间的空气分级效果,能够获得较低的NOx排放量和屏底烟气温度,降低炉膛宽度方向的屏底烟温偏差。引入再循环烟气后,再热器吸热量均有所上升,在炉膛底部引入再循环烟气对锅炉再热蒸汽温度的调整作用更好。

Flue gas recirculation technology can not only reduce the NOx generated during pulverized coal combustion, but also play a role in regulating the reheat steam temperature, which is one of the main means of low NOx combustion in boilers and regulating the reheat steam temperature, and numerous studies have been conducted on flue gas recirculation technology at home and abroad. However, the current domestic researches mainly focus on the impact of recir-culating flue gas flow rate on boiler combustion and heat transfer, and there is still a lack of de-tailed comparative research and analysis of various flue gas recirculation positions in large coal-fired power generation. Three-dimensional computational fluid dynamics simulations were per-formed for a 1 000 MW ultra-supercritical double-reheat tangentially fired tower-type boiler to in-vestigate the effects of the flue gas recirculation position on the combustion, NOx generation characteristics, the flue gas temperature at the screen bottom and furnace heat transfer. The re-sults show that among the four different flue gas recirculation positions, mixing the flue gas re-circulation with the primary air can strengthen the air staging effect, thus can obtain a lower NOx, a lower flue gas temperature at the screen bottom, and can reduce gas temperature devia-tion in the width of the furnace at screen bottom of the boiler. After the introduction of recircu-lating flue gas, the heat absorption of the reheater is increased, and the introduction of recirculat-ing flue gas at the bottom of the furnace has a better effect on adjusting the boiler reheat steam temperature.