ABSTRACT

The current reaction kinetics of coal–oxygen compound in water-soaked coal has not been accurately explained. Therefore, thermal behavior and microscopic characteristics during spontaneous combustion of water-soaked coal samples were analyzed. Five kinds of coal samples were selected with moisture contents of 5%, 10%, 15%, and 20% of the raw coal. Fourier transform infrared (FTIR), thermogravimetric (TG), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were adopted. The results showed that the hydroxyl (–OH) group is greatly affected by the moisture content of coal samples. The area of hydroxyl absorption peaks in coal samples with 5% and 10% moisture content increased by 1.76% and 1.12%, respectively. The critical temperature T₁ decreased the most at 10% moisture content compared with the raw coal, which was about 6.5 °C. This indicated that the heat storage process was accelerated and the activity of the coal samples was increased. According to the thermodynamic analysis, the activation energy of the five kinds of water-soaked coal samples are 148.078 kJ/mol, 147.674 kJ/mol, 146.197 kJ/mol, 145.019 kJ/mol, and 145.934 kJ/mol, respectively. This proves that the activation energy of coal samples is generally reduced after immersion in water, and coal samples with 15% moisture content are most susceptible to spontaneous combustion. As the temperature was raised, aliphatic hydrocarbons (–CH₃, – CH–) and C = O increased rapidly. The above results indicate that water immersion accelerates the spontaneous combustion and oxidation of coal to a certain extent.

摘要

目前尚未准确解释水浸煤中煤-氧化合物的反应动力学。因此，对水浸煤样自燃过程中的热行为和微观特征进行了分析。选取5种煤样，水分含量分别为原煤的5%、10%、15%和20%。采用傅里叶变换红外 (FTIR)、热重 (TG) 和漫反射红外傅里叶变换光谱 (DRIFTS)。结果表明，羟基（-OH）基团受煤样水分含量的影响很大。含水率为5%和10%的煤样中羟基吸收峰面积分别增加了1.76%和1.12%。临界温度 T ₁与原煤相比，水分含量在 10% 时下降幅度最大，约为 6.5 °C。这表明储热过程加快，煤样活性增加。根据热力学分析，5种水浸煤样的活化能分别为148.078 kJ/mol、147.674 kJ/mol、146.197 kJ/mol、145.019 kJ/mol和145.934 kJ/mol。这证明煤样浸水后活化能普遍降低，含水量为15%的煤样最容易自燃。随着温度的升高，脂肪烃（-CH ₃, – CH–) 和 C = O 迅速增加。上述结果表明，浸水在一定程度上加速了煤的自燃和氧化。