Coal-ammonia co-firing is a promising technology for reducing CO2 emissions in coal-fired boilers. However, coal-ammonia co-firing may cause significant NOx owing to the high nitrogen in ammonia. This study proposes a novel low-NOx swirl burner with a scalable dual-channel ammonia pipe for coal-ammonia co-firing, and evaluates the combustion and NOx formation under different ammonia ratios of the dual channels (i.e., inner and outer channels). The results show that the ammonia is injected into the low-oxygen and high-CO environment behind the internal recirculation zone, contributing to the ammonia pyrolysis and inhibiting the ammonia oxidation reaction. Low NOx is successfully achieved with high combustion efficiency. In addition, it is observed that the effect of the ammonia ratio of the dual channels on the combustion and NOx formation is slight for the high ammonia blending ratio (20 %), while it is prominent for the low ammonia blending ratio (10 %). Especially, for the low ammonia blending ratio, lower ammonia ratio in the outer channel can obtain high velocity of ammonia stream in the inner channel, contributing to NOx reduction. Overall, the cases with lower ROC (0.1, 0.2) are suggested with low NOx (below 120 ppm) and carbon content in fly ash (below 3.50 %) for the low ammonia blending ratio in this study.

中文翻译：

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一种新型煤氨共燃的低 NOx 旋流燃烧器：双通道中氨比对燃烧和 NOx 形成的影响


煤氨共燃是一种很有前途的技术，可以减少燃煤锅炉的二氧化碳排放。然而，由于氨中的高氮，煤-氨混合燃烧可能会产生大量的 NOx。本研究提出了一种新型的低 NOx 旋流燃烧器，该燃烧器具有可扩展的双通道氨管，用于煤氨共燃，并评估了双通道（即内通道和外通道）在不同氨比例下的燃烧和 NOx 形成。结果表明，氨被注入内部再循环区后面的低氧和高 CO 环境中，有助于氨热解并抑制氨氧化反应。成功实现了低 NOx 和高燃烧效率。此外，据观察，双通道的氨比对燃烧和 NOx 形成的影响对于高氨混合比 （20 %） 来说很小，而对于低氨混合比 （10 %） 则很突出。特别是，对于低氨混合比，外通道中较低的氨比可以在内通道中获得高速度的氨流，有助于减少 NOx。总体而言，在本研究中，由于氨混合比例低，建议飞灰中的低 NOx（低于 120 ppm）和碳含量（低于 3.50%），因此 ROC 较低 （0.1， 0.2） 的情况。