Co-firing biomass in an existing coal combustion boiler is a promising way to mitigate carbon emission in the context of global carbon neutrality. This paper investigated the effect of biomass injection location on combustion and NO_X formation characteristics in a 300-MWe tangential boiler co-firing with coal. Numerical models have been validated against experimental measurement for both pure coal firing and biomass/coal co-firing cases. Compared to pure coal firing, co-firing case with biomass injected into the highest layer can sustain a comparable temperature distribution profile along the furnace height, and generate a lower NO emission by around 20 ppm. By moving the biomass injection location downward, the temperature difference between co-firing and pure coal firing cases becomes larger, and the final NO emission increases continually from 222 to 240 ppm. When biomass is injected through the lowest layer, N element in biomass volatile is oxidized to NO directly because of the abundant oxygen; thus, NO emission turns to be the highest among all co-firing cases. Contrarily, when biomass is injected through the highest layer, the majority of N in biomass volatile is released as NH₃, and it further acts as a reduction agent for NO, thus leading to the lowest NO emission.

中文翻译：

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生物质混烧位置对 300 MWe 燃煤切线锅炉燃烧和 NOX 排放的影响

在现有的燃煤锅炉中混烧生物质是在全球碳中和的背景下减少碳排放的一种很有前途的方法。本文研究了生物质注入位置对燃烧和 NO _X的影响300-MWe 切向锅炉与煤混烧的形成特性。数值模型已针对纯煤燃烧和生物质/煤混烧情况的实验测量进行了验证。与纯煤燃烧相比，将生物质注入最高层的混烧情况可以沿炉高维持可比较的温度分布曲线，并产生约 20 ppm 的较低 NO 排放。通过将生物质注入位置向下移动，混烧和纯煤燃烧情况之间的温差变大，最终 NO 排放量从 222 ppm 持续增加至 240 ppm。当生物质通过最底层注入时，由于氧气含量丰富，生物质挥发物中的N元素直接被氧化成NO；因此，在所有共烧情况下，NO 排放量最高。_{如图3所示}，它进一步作为NO的还原剂，从而使NO排放量最低。