Abstract In order to investigate the effect of limestone on NO emission during petroleum coke combustion, experiments were conducted in a horizontal fixed-bed reactor connected with an on-line FTIR gas analyzer. Calcium based materials (limestone, CaO and CaSO4) were employed as solid additives, while CO2 and SO2 were mixed with the carrier gas to research their effects on NO emission. The results showed that char-N was the most important source of NO. Char-NO, which was produced by the combustion of char-N was significantly promoted with the addition of limestone. This was mostly caused by the catalytic effect of CaO, which was produced by the decomposition of limestone. To clarify the mechanism, pyrolysis experiments were carried out, and the transformation of fuel-N to gaseous-N and char-N was investigated. The conversion ratio of fuel-N to gaseous-N was promoted to a higher value by the additives, whereas the proportion of char-N slightly decreased. However, most of fuel-N still remained in char regardless of additives. Therefore, it could be concluded that the conversion ratio of char-N to NO obviously increased due to the addition of additives and then resulted in an increase in the overall emission of NO during combustion. The nitrogen species in raw material and chars were analyzed using X-ray photoelectron spectroscopy (XPS). The results showed that the conversion route of fuel-N to char-N during pyrolysis was not obviously affected by limestone, however, it was greatly affected by CaO. More nitrogen was restrained in the form of N-X in chars produced by the co-pyrolysis of petroleum coke and CaO, due to which, the positive effect of CaO on NO emission was weaker than that of the limestone.

中文翻译：

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石灰石对石油焦燃烧过程中NO排放的影响

摘要 为了研究石灰石对石油焦燃烧过程中NO排放的影响，在与在线FTIR气体分析仪相连的卧式固定床反应器中进行了实验。钙基材料（石灰石、CaO 和 CaSO4）用作固体添加剂，而 CO2 和 SO2 与载气混合以研究它们对 NO 排放的影响。结果表明，char-N是NO最重要的来源。加入石灰石后，炭-N 燃烧产生的炭-NO 得到显着促进。这主要是由于石灰石分解产生的CaO的催化作用造成的。为了阐明其机理，进行了热解实验，并研究了燃料-N向气态-N和焦-N的转化。燃料氮向气态氮的转化率被添加剂促进到更高的值，而炭氮的比例略有下降。然而，无论添加剂如何，大部分燃料-N 仍保留在炭中。因此，可以得出结论，由于添加了添加剂，炭-N 向 NO 的转化率明显增加，进而导致燃烧过程中 NO 的总体排放量增加。使用 X 射线光电子能谱 (XPS) 分析原料和炭中的氮物质。结果表明，热解过程中燃料-N向焦-N的转化路线受石灰石影响不明显，而受CaO影响较大。更多的氮以 NX 的形式被抑制在石油焦和 CaO 共热解产生的焦炭中，因此，