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基于LAMMPS的煤纳米孔隙中甲烷吸附/解吸和流动规律研究

石钰 刘洋 薛俊华 李树刚 张超

石钰,刘洋,薛俊华,等. 基于LAMMPS的煤纳米孔隙中甲烷吸附/解吸和流动规律研究[J]. 煤田地质与勘探,2023,51(4):37−45. doi: 10.12363/issn.1001-1986.22.10.0779
引用本文: 石钰,刘洋,薛俊华,等. 基于LAMMPS的煤纳米孔隙中甲烷吸附/解吸和流动规律研究[J]. 煤田地质与勘探,2023,51(4):37−45. doi: 10.12363/issn.1001-1986.22.10.0779
SHI Yu,LIU Yang,XUE Junhua,et al. Study on methane adsorption/desorption and flow law in the nanopores of coal based on LAMMPS[J]. Coal Geology & Exploration,2023,51(4):37−45. doi: 10.12363/issn.1001-1986.22.10.0779
Citation: SHI Yu,LIU Yang,XUE Junhua,et al. Study on methane adsorption/desorption and flow law in the nanopores of coal based on LAMMPS[J]. Coal Geology & Exploration,2023,51(4):37−45. doi: 10.12363/issn.1001-1986.22.10.0779

基于LAMMPS的煤纳米孔隙中甲烷吸附/解吸和流动规律研究

doi: 10.12363/issn.1001-1986.22.10.0779
基金项目: 国家自然科学基金项目(11802231,51974239,52174203)
详细信息
    第一作者:

    石钰,1986年生,女,陕西渭南人,博士,副教授,硕士生导师,从事非常规气体安全开采研究工作. E-mail:shiyu@xust.edu.cn

    通信作者:

    薛俊华,1963年生,男,江苏泰州人,博士,教授,博士生导师,从事煤矿开采理论和技术研究工作. E-mail:xuejunhua2003@163.com

  • 中图分类号: X936

Study on methane adsorption/desorption and flow law in the nanopores of coal based on LAMMPS

  • 摘要: 基于LAMMPS(Large-scale Atomic/Molecular Massively Parallel Simulator)分子动力学方法,研究煤纳米孔隙中驱动力、孔径、温度和压力对甲烷吸附/解吸和流动的影响规律。结果表明,随着驱动力增加,甲烷分子黏度逐渐减小,流动性增强,流动速度增大,滑移长度绝对值逐渐减小,流动趋近于无滑移状态。甲烷的吸附密度与驱动力无关,主要受气−固作用影响。甲烷在流动过程中会吸附于煤孔隙壁面,当煤孔径较小时,甲烷几乎全部吸附,无游离态甲烷。增大煤孔径,壁面范德华力对游离态甲烷影响减弱,甲烷流动速度增大,孔隙内出现大量游离态甲烷,甲烷由单峰分布转为2个对称的双峰分布。大孔径中甲烷黏度较低,流动性好,Hagen-Poiseuille方程更适用于较大孔径中的甲烷流动。升高温度,甲烷分子热运动增强,吸附层密度降低,甲烷流动速度增加,煤孔隙壁上吸附态甲烷解吸为游离态甲烷,甲烷流量增大。增大压力,孔隙内甲烷数量逐渐增多,甲烷分子间强烈的相互碰撞使得甲烷流动阻力增大,流速减小。从微观角度通过建立更加真实的模型阐明了煤纳米孔隙中甲烷吸附/解吸和流动机制,研究结果可为工程应用中促进甲烷解吸、提升煤层气开采效率提供理论基础。

     

  • 图  模型构建

    Fig. 1  Model construction

    图  不同尺寸的煤纳米孔隙模型

    Fig. 2  Nanopore models of coal with different sizes

    图  甲烷质量密度对比

    Fig. 3  Comparison of methane mass density

    图  不同驱动力下孔隙中甲烷的质量密度分布

    Fig. 4  Mass density distribution of methane in pore under different driving forces

    图  不同驱动力下孔隙中甲烷的速度分布

    Fig. 5  Velocity distribution of methane in pore under different driving forces

    图  不同驱动力下甲烷的滑移长度和黏度

    Fig. 6  Slip length and viscosity of methane under different driving forces

    图  不同孔径中甲烷质量密度分布

    Fig. 7  Methane density distribution in different pore sizes

    图  3.8~7.0 nm孔径中甲烷质量密度分布

    Fig. 8  Mass density distribution of methane in the pores size from 3.8 nm to 7.0 nm

    图  不同孔径中甲烷流动速度分布

    Fig. 9  Flow velocity distribution of methane under different pore sizes

    图  10  不同孔径下甲烷的滑移长度和黏度

    Fig. 10  Slip length and flow viscosity of methane under different pore sizes

    图  11  不同温度下甲烷的质量密度和运移速度分布

    Fig. 11  Mass density and flow velocity distribution of methane at different temperatures

    图  12  不同温度下甲烷数密度

    Fig. 12  Number density of methane at different temperatures

    图  13  温度与甲烷流量的关系

    Fig. 13  Relationship between temperature and methane flow rate

    图  14  不同压力下甲烷的质量密度与运移速度分布

    Fig. 14  Mass density and flow velocity distribution of methane under different pressures

    图  15  不同压力下甲烷数密度分布

    Fig. 15  Number density distribution of methane under different pressures

    表  1  不同压力下孔隙中甲烷数量和施加的驱动力

    Table  1  Amount of methane in the pores under different pressures and the applied driving force

    压力/MPa甲烷数量驱动力/[kcal·(mol·nm)−1]
    71000.012
    152000.006
    253000.004
    404000.003
    下载: 导出CSV
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  • 收稿日期:  2022-10-15
  • 修回日期:  2023-01-13
  • 刊出日期:  2023-04-25
  • 网络出版日期:  2023-04-19

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