Abstract The volatiles' reaction has a significant influence on the yield and quality of tar during pyrolysis of low-rank coals. To clarify the effect of volatiles' reaction on the coking behavior of tar, pyrolysis experiments of Naomaohu coal were conducted in fixed-bed and downer-bed reactors at various heating rates (10, 58 and >103 °C/min) and temperatures (550–800 °C). The tar composition was analyzed by gas chromatography with the simulated distillation method and a comprehensive two-dimensional gas chromatography/mass spectrometry. The structure of coke suspended in tar (Coke-S) and char was characterized by electron spin resonance, Raman and thermogravimetry. The reaction of volatiles during coal pyrolysis is more significant in the downer-bed reactor, due to the increased interaction between different volatile radical fragments or with char, leading to increased coke yield and lower tar quality. In addition, the volatile radical fragments are dominated by the core structure of aromatic carbon at higher than 650 °C in the downer-bed reactor. In the second thermal field in the downer-bed reactor, Coke-S produced by these fragments has more macromolecular structures and greater stability than char obtained at the same temperature.

中文翻译：

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脑毛湖煤下床反应器热解过程中挥发分反应对焦油焦化的影响

摘要 低阶煤热解过程中挥发物的反应对焦油的产率和质量有显着影响。为了阐明挥发物反应对焦油焦化行为的影响，在固定床和下层床反应器中，在不同的加热速率（10、58 和 >103 °C/min）和温度下进行了脑毛湖煤的热解实验（ 550–800 °C)。焦油成分通过气相色谱、模拟蒸馏法和综合二维气相色谱/质谱分析。焦炭悬浮在焦油（Coke-S）和炭中的结构通过电子自旋共振、拉曼和热重法表征。煤热解过程中挥发分的反应在下床反应器中更为显着，由于不同挥发性自由基碎片之间或与炭之间的相互作用增加，导致焦炭产量增加和焦油质量降低。此外，在低于 650 °C 的下床反应器中，挥发性自由基碎片主要由芳香碳的核心结构控制。在下层床反应器的第二个热场中，这些碎片产生的焦炭比相同温度下得到的焦炭具有更多的大分子结构和更高的稳定性。