To address the persistently high NO x production and the heightened overheating risk in the hopper of a 600-MWe, deep-air-staging, arch-fired boiler furnace (i.e., the reference furnace), a solution was devised with a staged arch-firing framework (SAF) and flue gas recirculation (FGR). This required establishing an appropriate position for the burner-FGR and confirming the viability of the SAF for the furnace. Comprehensive industrial-scale physical tests and computer simulations were conducted using the reference furnace. Subsequently, the furnace with SAF was examined with FGR introduced sequentially, first using a fuel-rich mixture, then using an inner secondary-air flow, and finally using an outer secondary-air flow (i.e., denoted in turn as FGR-FR, FGR-IS, and FGR-OS). Given this FGR-location order, the FGR’s functions about combustion degradation and NO inhibition weakened, resulting in increased NO x emissions and continuously decreasing burnout loss. Considering the satisfactory burnout levels across all three configurations, the FGR-FR configuration demonstrated the best reduction in NO x emissions, achieving NO x output of about 600 mg/m3 (O2 = 6%) and an unburnt combustible rate in fly ash of about 5%. Comparing the conditions before and after implementing the SAF indicated that the SAF enhanced combustion intensity and improved the utilisation of overfire air and hopper air, resulting in a further 33.3% reduction in NO x emissions without compromising burnout efficiency. Additionally, the SAF effectively mitigated the overheating risk in the hopper by significantly lowering local temperature levels by 400 K.

中文翻译：

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确认新型拱形燃烧解决方案在大型炉内安全强化低氮氧化物燃烧的功效：燃烧器中烟气再循环位置的影响

解决持续居高不下的NOX600 MW 的料斗内的生产和过热风险升高e，深空气分级拱火锅炉炉膛（即参考炉），设计了一种采用分级拱火框架（SAF）和烟气再循环（FGR）的解决方案。这需要为燃烧器-FGR 建立适当的位置，并确认 SAF 在熔炉中的可行性。使用参考炉进行了全面的工业规模物理测试和计算机模拟。随后，对带有SAF的炉子进行检查，依次引入FGR，首先使用富燃料混合物，然后使用内部二次空气流，最后使用外部二次空气流（即依次表示为FGR-FR， FGR-IS 和 FGR-OS）。鉴于这种 FGR 位置顺序，FGR 的燃烧降解和 NO 抑制功能减弱，导致 NO 增加X排放量和不断减少的燃尽损失。考虑到所有三种配置都令人满意的燃尽水平，FGR-FR 配置表现出最佳的 NO 减少效果X排放，实现 NOX产量约600毫克/立方米3（O2= 6%），飞灰中未燃烧的可燃率约为 5%。比较实施SAF前后的情况表明，SAF增强了燃烧强度，提高了过火空气和料斗空气的利用率，使得NO进一步减少了33.3%X排放而不影响燃尽效率。此外，SAF 将局部温度水平显着降低 400 K，有效降低了料斗中的过热风险。