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    基于TG–DSC探究煤热解热效应最佳测定条件

    Exploring the optimal measurement conditions of heat effects of coal pyrolysis based on TG–DSC

    • 摘要: 现有研究对煤热解热效应的关注不足,且相关研究结果存在较大差异,这可能与热效应测定方法、测定条件及 DSC 基线热流处理方法的不同有关。为建立更普适、准确、标准化的煤热解热效应测定方法,基于热重–差示扫描量热法(TG–DSC),研究了主要测定条件对煤热解热效应的影响,以确定最佳测定条件。在此基础上,对兖矿烟煤的热解热效应进行探究,根据TG/DSC/DTG曲线进行热力学分析,采用经验法处理DSC基线热流,划分热解过程并对热解热效应进行定性定量分析。结果表明,煤热解热效应的最佳测定条件如下:坩埚类型为70 μL铂金坩埚内套50 μL氧化铝坩埚,加盖;煤颗粒粒径< 75 μm;煤样重量10 mg;煤样装填方式为不压实;热解气氛为Ar;气体流量80 mL/min;热解终温1100 ℃;升温速率10 ℃/min。在最佳测定条件下,采用经验法以样条曲线作为基线对DSC热流曲线取峰,将兖矿烟煤热解过程划分为5个阶段:热解前期分为3个吸热段,后期分为2个放热段。全过程吸热−160.13 J/g,放热+641.05 J/g,总热效应为+480.92 J/g(放热)。

       

      Abstract: There have been few studies on the heat effects of coal pyrolysis in the past, and the results of heat effects research have also varied. This may be caused by different methods of measuring heat effects, measurement conditions, and methods of treating DSC baseline heat flow. In order to determine the heat effects of coal pyrolysis more universally, accurately, and standardly, based on thermogravimetric differential scanning calorimetry (TG–DSC) to study the influence of main measurement conditions on the heat effects of coal pyrolysis, in order to determine the optimal measurement conditions. Then, based on the optimal measurement conditions, the heat effects of Yankuang bituminous coal pyrolysis was explored. Thermodynamics analysis was carried out according to the TG/DSC/DTG curves, and empirical methods were used to treat the DSC baseline heat flow. The pyrolysis process was divided and the heat effects of coal pyrolysis were qualitatively and quantitatively analyzed. The results indicate that the optimal conditions for determining the heat effects of coal pyrolysis are as follows: crucible type is a 70 μL platinum crucible with a 50 μL standard capped alumina crucible, coal particle size<75 μm, coal sample weight 10 mg; coal sample loading method is not compacted, pyrolysis atmosphere is Ar, gas flow rate 80 mL/min, pyrolysis final temperature 1100 ℃, heating rate 10 ℃/min. Under the optimal measurement conditions, empirical methods were used to peak the DSC heat flow curve using spline curves as baseline. The pyrolysis process of Yankuang bituminous coal was divided into five stages, with three endothermic stages in the early stage and two exothermic stages in the late stage. The total process heat absorption was −160.13 J/g, heat release was +641.05 J/g, and the total heat effects of heat release were +480.92 J/g.

       

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