College of Safety and Emergency Management Engineering, Taiyuan University of Technology
Key Laboratory of Ministry of Education for In-situ Property Improving Mining, Taiyuan University of Technology

为了研究煤的非均匀势阱分布及其对甲烷吸附/解吸过程的影响，在吸附科学和分子动力学理论基础上建立了非均匀势阱模型。该模型可以表征煤的吸附/解吸性能以及精确计算出煤体内不同势阱所对应的势阱数量。为了验证非均匀势阱模型对煤的吸附/解吸性能方面的表征能力的准确性，将其与Langmuir模型分别对甲烷吸附/解吸过程进行拟合，再将拟合数据和等温吸附线的相关系数分别进行比较。结果表明，非均匀势阱模型在表征煤体的吸附/解吸性能方面更优。在研究煤体内的势阱分布时，发现煤在不同温度压力下对甲烷的吸附/解吸过程中，煤体内的势阱分布出现明显差异。在分析煤的势阱规律时，发现在吸附阶段煤体内的势阱数量比解吸阶段多，但解吸过程中煤的平均势阱深度比吸附过程大。并且平均势阱深度随着煤阶的降低而降低。在吸附阶段势阱数量集中在某个势阱深度的范围内，但在解吸阶段势阱数量的分布相较而言就更分散。在同一温度下，势阱数量随着煤阶的降低而减少。从势阱分布来看，在相同温度下，高煤阶煤的势阱分布方差明显比低煤阶煤的势阱分布方差要大得多。温度上升会使得平均势阱深度随着温度的升高而下降。对于同一煤阶而言，温度的变化对5～15 kJ/mol内的势阱深度影响更大，且这种现象在低阶煤中更为明显。研究发现，势阱深度较大的势阱更能抵抗温度变化对其产生的影响。在煤体加热或加压过程中，甲烷吸附/解吸率的非线性变化是由势阱的不均匀性引起的。

In order to study the non-uniform potential well distribution of coal and its effect on the methane adsorption/desorption process, a non-uniform potential well model based on adsorption science and molecular dynamics theory was developed in this study. The model characterizes the adsorption/desorption properties of coal, and accurately calculates the number of potential wells corresponding to different potential wells in the coal. To verify the accuracy of the characterization ability of the non-uniform potential well model in terms of coal adsorption/desorption performance, it was fitted separately to the Langmuir model for the methane adsorption/desorption process, and then the correlation coefficients of the fitted data and isothermal adsorption lines were compared separately. The results show that the non-uniform potential well model is superior in characterizing the adsorption/desorption performance of the coal body. In the study of the potential well distribution within the coal, it was found that the potential well distribution within the coal shows some significant differences during the adsorption/desorption of methane by the coal at different temperatures and pressures. In the analysis of the potential well pattern of coal, it was found that the number of potential wells in the coal is more in the adsorption phase than in the desorption phase, but the average potential well depth in the coal is larger in the desorption process than in the adsorption process. And the average potential well depth decreases as the coal rank decreases. In the adsorption phase, the number of potential wells is concentrated within a certain range of potential depth, but in the desorption phase, the distribution of the number of potential wells is more dispersed in comparison. At the same temperature, the number of potential wells decreases with decreasing coal rank. In terms of the potential well distribution, the variance of the potential well distribution is significantly larger for high rank coals than for low rank coals at the same temperature. An increase in temperature causes the average potential well depth to decrease as the temperature increases. For the same coal rank, the change in temperature has a greater effect on the potential well depth in the range of 5−15 kJ/mol, and this phenomenon is more pronounced in lower rank coals. In the study, it was found that the potential wells with larger potential well depths are more resistant to the effects of temperature variations on them. The nonlinear variation of methane adsorption/desorption rates during the heating or pressurization of the coal body is caused by the inhomogeneity of the potential wells.

国家自然科学基金资助项目(12102293)

王金鑫，周动，冯雪健，等. 煤的非均匀势阱分布及其对甲烷吸附/解吸的影响[J]. 煤炭学报，2023，48(10)：3818−3830.

WANG Jinxin，ZHOU Dong，FENG Xuejian，et al. Study of non-uniform potential well distribution of coal and its effect on methane adsorption/desorption[J]. Journal of China Coal Society，2023，48(10)：3818−3830.