A sensitive thermogravimetric analysis and differential scanning calorimetry (TG-DSC) apparatus enabled accurate measurement of the heat of adsorption/desorption of water on/from coal at temperatures over 100 °C. This technique was first used to measure the heat of desorption of water during the thermal drying of as-received coal. For three low-rank coals, the heats of desorption were almost constant at 2300–2350 kJ/kg until the water content decreased to 0.35 kg/kg-dried coal, which is close to the heat of vaporization, and gradually increased to reach ∼5000 kJ/kg at the completion of drying at 107 °C. The role of adsorption of water vapor on the dried coal in relation to the coal–oxygen interaction was then examined to evaluate the propensity to spontaneous heating of dried coal. For the three coals tested, the heat generated by the adsorption of water vapor from moist air with a relative humidity of 0.15 was 90–130 kJ/kg-dried coal in 30 min; these values are 1.2–4 times larger than the heats generated by the coal–oxygen interaction, even at 107 °C. This observation suggests that the adsorption of water vapor plays an important role in the spontaneous heating of coal, even over 100 °C. The transient changes in the heats of adsorption/desorption of water on the approach to equilibrium were also successfully estimated and discussed in relation to the isosteric heat of adsorption/desorption and heat of vaporization of water.

中文翻译：

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TG-DSC研究测量煤热干燥过程中水的解吸热，并研究水蒸气的吸附在检查煤自热超过100°C时的作用

灵敏的热重分析和差示扫描量热仪（TG-DSC）能够在超过100°C的温度下准确测量煤上水/煤中水的吸附/解吸热。该技术首先用于测量原煤干燥过程中水的解吸热量。对于三种低阶煤，解吸热几乎恒定在2300–2350 kJ / kg，直到含水量降至0.35 kg / kg干燥煤为止，这接近于汽化热，并逐渐增加至〜在107°C下完成干燥时为5000 kJ / kg。然后研究了水蒸气在干煤上的吸附与煤-氧相互作用的关系，以评估干煤自发加热的倾向。对于测试的三种煤，在相对湿度为0.15的潮湿空气中，水蒸气的吸附所产生的热量在30分钟内为90-130 kJ / kg干燥煤。即使在107°C时，这些值也比煤-氧相互作用产生的热量大1.2–4倍。该观察结果表明，即使在超过100°C的温度下，水蒸气的吸附在煤的自热加热中也起着重要作用。还成功地估计和讨论了水在平衡过程中吸附/解吸热的瞬态变化，并将其与等温吸附/解吸热和水的汽化热进行了讨论。该观察结果表明，即使在超过100°C的温度下，水蒸气的吸附在煤的自热加热中也起着重要作用。还成功地估计和讨论了水在平衡过程中吸附/解吸热的瞬态变化，并将其与等温吸附/解吸热和水的汽化热进行了讨论。该观察结果表明，即使在超过100°C的温度下，水蒸气的吸附在煤的自热加热中也起着重要作用。还成功地估计和讨论了水在平衡过程中吸附/解吸热的瞬态变化，并将其与等温吸附/解吸热和水的汽化热进行了讨论。