Abstract

Knowledge on pyrolysis of low-rank coals is of vital important since it has significant effect on their thermal conversion such as gasification, liquefaction, and combustion. However, kinetic background on pyrolysis of different low-rank coals is still insufficient. In this work, pyrolysis of three low-rank coals, i.e., Xilinguole lignite (XL), Naomaohu lignite (NL), and Shenmu-Fugu subbituminous coal (SBC), was performed in a thermogravimetric analyzer from room temperature to 1000°C at different heating rates (10, 20, and 30 K/min). Kinetic parameters including activation energy, reaction order, and pre-exponential factor were determined using three different kinetic models, i.e., Kissinger-Akahira-Sunose (KAS) model, Ozawa-Flynn-Wall (OFW) model, and Coats-Redfern (CR) method. The results show that KAS and OFW models are almost equally effective for calculating activation energy, which varies remarkably from 26.4 to 141.7 kJ/mol for different low-rank coals but all firstly increases with the pyrolysis progress and then decreases. Reaction order and pre-exponential factor determined by CR method vary with different low-rank coals and heating rates.

中文翻译：

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使用三种无模型方法的低阶煤热解动力学

摘要

低阶煤的热解知识非常重要，因为它对它们的热转化如气化、液化和燃烧有显着影响。然而，不同低阶煤热解的动力学背景仍然不足。在这项工作中，三种低阶煤，即锡林郭勒褐煤（XL）、淖毛湖褐煤（NL）和神木府谷次烟煤（SBC），在热重分析仪中进行了从室温到1000°C的热解。不同的加热速率（10、20 和 30 K/min）。包括活化能、反应级数和指前因子在内的动力学参数使用三种不同的动力学模型确定，即 Kissinger-Akahira-Sunose (KAS) 模型、Ozawa-Flynn-Wall (OFW) 模型和 Coats-Redfern (CR) ） 方法。结果表明，KAS 和 OFW 模型在计算活化能方面几乎同样有效，对于不同的低阶煤，活化能从 26.4 到 141.7 kJ/mol 变化显着，但均随着热解过程的进行先增大后减小。CR法确定的反应级数和指前因子随低阶煤和升温速率的不同而不同。