Limitation of Barrell formula in calculating gas diffusion coefficient of coal

doi:10.16265/j.cnki.issn1003-3033.2020.02.012

Abstract

Abstract: In order to study limitation of Barrel method in calculating gas diffusion coefficient of coal as an approximate solution of diffusion model, numerical calculation and theoretical approximation method for diffusion coefficient were adopted, and numerical and theoretical solutions of diffusion coefficient calculated through average concentration model and gas-bearing feature model were compared. Then, Barrel method was analyzed only considering gas content gradient but not influence of gas-bearing state on calculation accuracy of diffusion coefficient. The research shows that numerical solutions of Barrel method and time-varying coefficient method are basically consistent with theoretical solutions when average concentration model is applied while their calculation results will decline first and maintain a stable trend in case of gas-bearing characteristic model. Gas content gradient is a premise assumption of diffusion dynamics in a theoretical model, which causes calculated value of diffusion coefficient to be smaller than actual one.

Key words: Barrel method, diffusion coefficient, physical model, content gradient, Comsol

CLC Number:

X936

JIA Hongfu, AN Fenghua, PENG Xinshan. Limitation of Barrell formula in calculating gas diffusion coefficient of coal[J]. China Safety Science Journal, 2020, 30(2): 73-78.

References 16

[1]	BARRER R. Difussion in and through solid [M]. Cambridge: Cambridge University Press,1951: 28-30.
[2]	CHARRIERE D, POKRYSZKA Z, BEHRA P. Effect of pressure and temperature on diffusion of CO2 and CH4 into coal from the Lorraine basin (France)[J]. International Journal of Coal Geology, 2010,81(4): 373-380.
[3]	郭勇义, 吴世跃, 王跃明, 等. 煤粒瓦斯扩散及扩散系数测定方法的研究[J]. 山西矿业学院学报, 1997,15(1): 17-21.GUO Yongyi, WU Shiyue, WANG Yueming, et al. Research on coal particle gas diffusion and determination of diffusion coefficient [J].Shanxi Mining Institutele Journal, 1997,15 (1):17-21.
[4]	杨其銮, 王佑安. 煤屑瓦斯扩散理论及其应用[J]. 煤炭学报, 1986,11(3): 87-94.YANG Qiluan, WANG Youan. Coal dust gas diffusion theory and its application [J]. Journal of China Coal Society, 1986,11(3):87-94.
[5]	聂百胜, 王恩元, 郭勇义, 等. 煤粒瓦斯扩散的数学物理模型[J]. 辽宁工程技术大学学报:自然科学版, 1999,18(6): 582-585.NIE Baisheng, WANG Enyuan, GUO Yongyi, et al. Mathematical and physical model of coal particle gas diffusion [J]. Journal of Liaoning Technical University:Natural Science Edition, 1999,18 (6):582-585.
[6]	张志刚. 煤粒中瓦斯时变扩散规律的解析研究[J]. 煤矿开采, 2012,17(2): 8-11.ZHANG Zhigang. Resolving of methane time-varying diffusion rule in coal grain [J]. Coal Mining Technology, 2012,17 (2):8-11.
[7]	岳高伟, 王兆丰, 康博. 低温环境煤的瓦斯扩散系数时变特性[J]. 中国安全科学学报, 2014,24(2): 107-112.YUE Gaowei, WANG Zhaofeng, KANG Bo. Time-varying characteristics of gas diffusion coefficient of coal in low temperature environment [J]. China Safety Science Journal, 2014,24 (2):107-112.
[8]	ZHAO Yunmei, ZHANG Jinyun, DING Shurong. A new method for solving the fission gas diffusion equations with time-varying diffusion coefficient and source term considering recrystallization of fuel grains[J]. Nuclear Materials and Energy, 2019,20:100686.
[9]	温志辉, 段昕均, 王洪磊. 煤屑瓦斯扩散系数时间响应规律研究[J]. 河南理工大学学报:自然科学版, 2017,36(6): 33-39.WEN Zhihui, DUAN Xinjun, WANG Honglei. Study on time response law of methane diffusion coefficient of coal cuttings [J]. Journal of Henan Polytechnic University:Natural Science, 2017,36 (6):33-39.
[10]	袁军伟. 颗粒煤瓦斯扩散时效特性研究[D].北京: 中国矿业大学(北京), 2014.YUAN Junwei. Study on time-related characteristics of gas diffusion from particles coal [D]. Beijing:China University of Mining and Technology(Beijing), 2014.
[11]	李志强, 王登科, 宋党育. 新扩散模型下温度对煤粒瓦斯动态扩散系数的影响[J]. 煤炭学报, 2015,40(5): 1 055-1 064.LI Zhiqiang, WANG Dengke, SONG Dangyu. Influence of temperature on dynamic diffusion coefficient of CH4 into coal particles by new diffusion model [J]. Journal of China Coal Society, 2015,40 (5):1 055-1 064.
[12]	简星, 关平, 张巍. 煤中 CO2的吸附和扩散:实验与建模 [J]. 中国科学: 地球科学, 2012, 42(4):492-504.JIAN Xing, GUAN Ping, ZHANG Wei. Carbon dioxide sorption and diffusion in coals: experimental investigation and modeling [J]. Scientia Sinica: Terrae, 2012, 42(4):492-504.
[13]	杨其銮. 煤屑瓦斯放散随时间变化规律的初步探讨[J]. 煤矿安全, 1986,17(4): 3-11.YANG Qiluan. Preliminary discussion on the time variation of coal dust gas dispersion [J]. Safety in Coal Mines, 1986,17(4):3-11.
[14]	王兆丰. 空气、水和泥浆介质中煤的瓦斯解吸规律与应用研究 [D]. 徐州:中国矿业大学,2001.WANG Zhaofeng. Gas desorption law and application of coal in air, water and mud media [D].Xuzhou: China University of Mining and Technology, 2001.
[15]	VALKOVSKA D S, DANOV K. Determination of bulk and surface diffusion coefficients from experimental data for thin liquid film drainage [J]. Journal of Colloid and Interface Science, 2000, 223(2):314-316.
[16]	HIGASHI K, OYA A, OISHI J. Surface diffusion phenomena in gaseous diffusion, (III) isotope effect on surface diffusion flow[J]. Mechanical Science & Technology, 1966, 3(2): 51-56.