To reduce CO₂ emissions from coal-fired plants, coal/NH₃ cocombustion has received widespread attention. In this work, the influence of NH₃ on coal combustion kinetics during coal/NH₃ cocombustion was studied by constant temperature thermogravimetric experiment and reactive molecular dynamics (ReaxFF MD). The experimental results show that coal combustion is inhibited during coal/NH₃ cocombustion. The weight loss of coal during coal/NH₃ cocombustion was always slower than that during pure coal combustion at all temperatures, and the burn out time of coal increases by 20–30s. The higher the NH₃ cofiring ratio, the slower the weight loss rate of coal. When the NH₃ cofiring ratio increases from 0 to 60%, the burnout time of coal increases by about 25%. The higher the carbon content in coal, the more obvious is the inhibition effect of NH₃ on coal combustion. The inhibitory mechanism of NH₃ on coal was then studied by ReaxFF MD. It is found that the combustion of coal during coal/NH₃ cocombustion is inhibited mainly because NH₃ will compete with coal for O₂. Compared to pure coal combustion and pure NH₃ combustion, the transfer of O to nitrogen oxides increases by about 1.5 times while the transfer of O to carbon oxides decreases by about 10% during coal/NH₃ cocombustion. This proves that NH₃ dominates in competition for O₂. Compared with pure coal combustion, the combustion of char, tar, and carbonaceous gas from coal during coal/NH₃ cocombustion is restrained. The decrease rate of H/C ratio of char will slow down. The attachment of O molecules on char will also decrease. These further confirm that NH₃ inhibits coal combustion by competing with coal for O₂. In this work, the competition mechanism during coal/NH₃ cocombustion is studied, which is helpful for the development of stable coal combustion and unburned carbon emission reduction technology.

中文翻译：

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煤/NH3 共燃过程中 NH3 对煤燃烧动力学的影响：实验和 ReaxFF MD 模拟

为了减少燃煤电厂CO _{2排放，煤/NH 3}共燃受到广泛关注。本工作通过恒温热重实验和反应分子动力学(ReaxFF MD)研究了NH _{3对煤/NH 3}共燃过程中煤燃烧动力学的影响。实验结果表明，煤/NH ₃共燃过程中煤的燃烧受到抑制。在所有温度下，煤/NH ₃共燃过程中煤的失重始终慢于纯煤燃烧，并且煤的燃尽时间增加了20~30s。 NH ₃混烧比越高，煤的失重速度越慢。当NH ₃混烧比从0增加到60%时，煤的燃尽时间增加约25%。煤中碳含量越高，NH ₃对煤燃烧的抑制作用越明显。然后利用ReaxFF MD研究了NH ₃对煤的抑制机理。研究发现，煤/NH ₃混燃过程中煤的燃烧受到抑制主要是因为NH ₃会与煤竞争O ₂。与纯煤燃烧和纯NH ₃燃烧相比，煤/NH ₃共燃过程中O向氮氧化物的转移增加了约1.5倍，而O向碳氧化物的转移减少了约10％。这证明NH _{3在与O 2}的竞争中占主导地位。与纯煤燃烧相比，煤/NH ₃混燃过程中煤中的焦油、焦油和含碳气体的燃烧受到抑制。炭的H/C比下降速度将减慢。 O分子在炭上的附着也会减少。这些进一步证实NH ₃通过与煤竞争O ₂来抑制煤燃烧。本工作研究了煤/NH ₃共燃过程中的竞争机制，有助于煤炭稳定燃烧和不燃碳减排技术的发展。