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Heat effects of pyrolysis of 15 acid washed coals in a DSC/TGA-MS system

机译：DSC / TGA-MS系统中15酸洗涤煤热解的热效应

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摘要

Heat effects of coal pyrolysis are seldomly studied in the past and the few studies available in the literature differ from each other. The problem perhaps arises from the unclear definition of thermal steady state of differential scanning calorimetry (DSC), the different effects of minerals in coals, and the different mass bases used to quantify the heat flows. This work studies the heat effects during pyrolysis of 15 acid washed coals (D-coals), ranked from lignite to anthracite, in the temperature range of 117-900 degrees C in a system that couples DSC with a thermal gravimetric analyzer (TGA) and a mass spectrometer (MS). The steady state criteria of DSC are studied. The heat effects studied include the total pyrolysis heat (sensible heat + reaction heat) and the reaction heat. It is found that the time needed to reach the steady state for DSC is longer than that for TGA. The in situ char pyrolysis following the coal pyrolysis involves mass loss and reaction heat, so its profile should not be used to estimate the thermal capacity of coal. The reaction heat on DTG basis (q(r-DTG)) correlates better with C% of coals than that on the initial coal basis, both of them are endothermic in the temperature range of 560 degrees C and turn to exothermic at higher temperatures. It is also found that the major endothermic q(r-DTG) occurs prior to the main DTG peak; the major exothermic q(r-DTG) occurs upon the completion of the main DTG peak, about 130 degrees C higher than the DTG peak temperature; the radical concentration of char increases with increasing temperature during the evolution of the main DTG peak, but starts to decrease at the completion of the main DTG peak, around 600 degrees C, and then diminishes at around 750 degrees C.
机译：过去的煤热解的热效应很少研究，文献中的少数有可用的研究彼此不同。问题可能是由于差分扫描量热法（DSC）的热稳态的不明确定义，煤中矿物质的不同效果，以及用于量化热流的不同质量碱。这项工作研究了15酸洗涤的煤（D-煤）的热解期间的热效应，从褐煤中排名，在117-900摄氏度的温度范围内，在与热重分析仪（TGA）耦合的系统中的117-900摄氏度中质谱仪（MS）。研究了DSC的稳态标准。所研究的热效应包括总热解热（明智的热+反应热）和反应热。发现达到DSC稳定状态所需的时间比TGA更长。煤热解后的原位炭热解涉及质量损失和反应热量，因此其轮廓不应用于估计煤的热容量。 DTG的反应热量（Q（R-DTG））与煤中的C％相关，而不是在初始煤的基础上，在<560℃的温度范围内，两者都在吸热，然后在较高温度下转动放热。还发现主要吸热Q（R-DTG）在主DTG峰之前发生;主要的放热Q（R-DTG）在主DTG峰完成后发生，高于DTG峰值温度约130℃; Char的激进浓度随着温度的升高在主DTG峰的演变期间增加，但在主DTG峰完成时开始减少600℃，然后在750℃左右减少。

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  • 来源
    《Fuel》 |2020年第may15期|117325.1-117325.10|共10页
  • 作者

    Cheng Xiaojie; Shi Lei; Liu Qingya; Liu Zhenyu;

  • 作者单位

    Beijing Univ Chem Technol State Key Lab Chem Resource Engn Beijing 100029 Peoples R China;

    Beijing Univ Chem Technol State Key Lab Chem Resource Engn Beijing 100029 Peoples R China;

    Beijing Univ Chem Technol State Key Lab Chem Resource Engn Beijing 100029 Peoples R China;

    Beijing Univ Chem Technol State Key Lab Chem Resource Engn Beijing 100029 Peoples R China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Coal; Pyrolysis; DSC; TG; Radicals;

    机译：煤;热解;DSC;TG;自由基;

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