Method of determining baseline heat flow in measurement of coal pyrolysis reaction heat by TG-DSC
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摘要: 利用差示扫描量热仪测定煤热解反应热,仪器输出的总热流信号是由反应热热流和基线热流组成,故基线热流的确定成为测定反应热的关键。论文分析了TG-DSC测定煤及其他非均质有机物热解反应热过程中基线热流的构成,比较了经验法和测定法确定基线热流的优缺点,评估了基线热流各组分的测定方法,尤其关注这些方法对煤热解反应热测定时获取基线热流的可借鉴性。结果表明,TG-DSC测定煤热解反应热时,基线热流是由显热热流和辐射热流差组成;显热热流可借助Merrick模型、灰分比热容经验公式及混合物模型计算求出,辐射热流差则通过研究提出的辐射校正因子λ,将煤热解过程与煤焦热解过程关联后计算确定。最终,由显热热流和辐射热流差之和确定热解过程的基线热流。Abstract: When applied in the measurement of coal pyrolysis reaction heat,the differential scanning calorimeter outputs a total heat flow signal which is composed by reaction heat flow and baseline flow.Hence,determination of baseline heat flow is the key to accurately measuring the coal pyrolysis reaction heat.The composition of the baseline heat flow in the process of measuring pyrolysis reaction heat of coal and other heterogeneous organic matters by TG-DSC technique was theoretically analyzed in this paper,then the comparison of empirical methods with the testing approaches to determining the baseline heat flow was conducted.Finally the evaluation of the testing approaching to determining the baseline heat flow for each consisting part was carried out,in which particular attention was focused on their application possibility in the determination method of baseline heat flow.Results show that during the measurement of coal pyrolysis reaction heat by TG-DSC,the baseline heat flow consists of two parts,namely,sensible heat flow and radiation heat flow difference.On the basis of thermal analysis parameters which are obtained by TG-DSC in the measurement of coal pyrolysis reaction heat,sensible heat flow could be calculated by using Merrick model,mixture model,empirical formula of ash specific heat,etc.As for radiation heat flow difference,it could be obtained by correction factor λ after relating the process of coal pyrolysis with char pyrolysis.Finally,the baseline heat flow of coal pyrolysis reaction is determined by the sum of sensible heat and radiation heat flow difference.
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Key words:
- coal pyrolysis /
- reaction heat /
- TG-DSC /
- baseline heat flow /
- radiation correction factor λ
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