煤中吸附态与游离态甲烷的串联扩散特征及理论表征  

Deformation and failure characteristics of gas drainage drilling-reaming coal mass in non-uniform stress field

作　　者：程远平[1,3,4] 易明浩 王亮 CHENG Yuanping;YI Minghao;WANG Liang(School of Safety Engineering,China University of Mining and Technology,Xuzhou 221116,China;School of Resource&Environment and Safety Engineering,Hunan University of Science and Technology,Xiangtan 411201,China;Key Laboratory of Gas and Fire Control for Coal Mines l,Xuzhou 221116,China;National Engineering Research Center for Coal Gas Control,Xuzhou 221116,China)

机构地区：[1]中国矿业大学安全工程学院,江苏徐州221116 [2]湖南科技大学资源环境与安全工程学院,湖南湘潭411201 [3]煤矿瓦斯与火灾防治教育部重点实验室,江苏徐州221116 [4]煤矿瓦斯治理国家工程研究中心,江苏徐州221116

出　　处：《煤炭学报》2025年第1期326-339,共14页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(52034008,52374240,52404203)。

摘　　要：厘清煤中孔隙结构对甲烷吸附以及扩散的内在联系是定量评价甲烷解吸量和解吸速度的基础。运用低压氮气和低压二氧化碳吸附法对煤中多尺度孔隙进行了定量表征,获得吸附态和游离态甲烷的赋存场所和运移通道分别为0.38~1.5 nm的填充孔和1.5~100 nm的扩散孔,在此基础上建立了填充孔吸附态扩散和扩散孔游离态扩散的双孔串联扩散模型,并通过对甲烷解吸实验数据的拟合获得了甲烷扩散参数和孔隙结构参数。结果表明:基于多尺度孔隙甲烷吸附模型计算的甲烷极限吸附量与实测值匹配程度较好,其中90%以上的吸附态甲烷以微孔填充形式赋存于填充孔内,表明煤对甲烷的吸附能力取决于填充孔结构;解吸过程中填充孔内发生吸附态甲烷扩散,并不断流入扩散孔中以游离态扩散的形式流出,其中吸附态和游离态甲烷扩散系数分别处于10^(-13) m^(2)/s和10^(-6) m^(2)/s量级,而填充孔和扩散孔当量孔长分别为0.109~2.855μm和0.525~3.106 mm,对应的当量孔数分别为10^(16)~10^(17)个/g和10^(10)~10^(12)个/g;由于填充孔数量更多、孔长更短,吸附态甲烷浓度更高,煤中吸附态甲烷的质量传输速度要远大于扩散孔内的游离态甲烷,煤中甲烷的解吸主要受到扩散孔中游离态甲烷扩散过程的控制。Clarifying the internal relationship between pore structure and methane adsorption and diffusion in coal is the basis for quantitative evaluation of methane desorption.The multi-scale pores in coal were quantitatively characterized by the low-pressure nitrogen and carbon dioxide adsorption methods,and the occurrence sites and migration channels of adsorbed and free methane were determined as filling pores with size of 0.38-1.5 nm and diffusion pores with size of 1.5-100 nm,respectively.A dual-pore series diffusion model of adsorbed methane in filling pores and free methane in diffusion pores was established.The methane diffusion coefficient and pore structure parameters were obtained by fitting the methane desorption data of coal particles.The results indicate that the calculated methane limiting adsorption based on multi-scale pore methane adsorption model matches the measured value well.More than 90%of adsorbed methane is stored in filled pores in the form of micropore filling,and the methane adsorption ability in coal depends on the filled pores.During methane desorption,the adsorbed methane first diffuses in filled pores,and then flows out of coal in free phase through the diffusion pores.The adsorbed and free methane diffusion coefficients are in the order of magnitude of 10^(-13) m^(2)/s and 10^(-6) m^(2)/s,the equivalent pore lengths of filling and diffusion pores are 0.109-2.855μm and 0.525-3.106 mm,and the corresponding equivalent pore numbers per unit mass of coal are10^(16)~10^(17) g and 10^(10)~10^(12) g,respectively.Due to more filled pores with shorter pore lengths and higher adsorbed methane concentration,the mass transfer rate of adsorbed methane in coal is much faster than that of free methane in diffusion pores,and the methane desorption in coal is mainly controlled by the free methane diffusion process in diffusion pores.

关 键 词：孔隙结构 微孔填充 扩散模型 甲烷赋存 煤粒解吸 

分 类 号：TD713[矿业工程—矿井通风与安全]