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Theoretical and experimental investigation on the effect of CO on N migration and conversion during air-staged coal combustion
Journal of the Energy Institute ( IF 5.7 ) Pub Date : 2021-04-29 , DOI: 10.1016/j.joei.2021.04.012
Ping Chen , Peipei Wang , Mingyan Gu , Yao Fang , Kun Luo , Jianren Fan

Air-staging combustion is the widely-used low-nitrogen combustion technology. In this process of NOx reduction, the role played by CO resulted from the air-staged combustion cannot be ignored. In this study, quantum chemistry method is used to investigate the effects of the CO on the NOx generation/reduction and on the char surface. Theoretical calculations indicate that CO is involved in nitrogen fixation during the migration and transformation of N. During the oxidation of N-containing char, CO increases the binding energy of N of pyridine with adjacent C atoms, which is not conducive to the N precipitation. During reduction of NOx by char, CO decreases the desorption energy barrier of N2 and promotes NO heterogeneous reduction. On the other hand, CO promotes the re-embedding of N in generated NO into the char to form char-N. XPS experiments are carried out for the coal char samples after the air-staged combustion. The experimental results show that high CO concentration is conducive to retention N. When the excess air coefficient (α) is 0.8, the increase of N-6 content is 7.2% larger than that of α = 0.9. This work discovers the nitrogen fixation of CO, enriches and expands the understanding of the role of CO.



中文翻译:

CO对空燃煤燃烧过程中氮迁移转化的影响的理论和实验研究

空气分级燃烧是广泛使用的低氮燃烧技术。在此NO x还原过程中,不可忽视的是由空气阶段燃烧产生的CO所起的作用。在这项研究中,使用量子化学方法研究了CO对NO x生成/还原以及炭表面上的影响。理论计算表明,CO在N的迁移和转化过程中参与固氮作用。在氧化含N的碳的过程中,CO增加了吡啶N与相邻C原子的结合能,这不利于N的析出。在通过炭还原NO x的过程中,CO降低N 2的解吸能垒并促进NO异质还原。另一方面,CO促进将生成的NO中的N重新嵌入到char中以形成char-N。在空气分级燃烧后,对煤焦样品进行了XPS实验。实验结果表明,较高的CO浓度有助于保留N。当过量空气系数(α)为0.8时,N-6含量的增加比α= 0.9的增加7.2%。这项工作发现了CO的固氮作用,丰富并扩展了对CO作用的认识。

更新日期:2021-05-05
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