Pore structure and fractal characteristics of outburst coal in northern Guizhou

doi:10.16265/j.cnki.issn1003-3033.2020.02.011

Abstract

Abstract: In order to reveal effects of outburst coal's pore structure on gas adsorption capacity and emission performance, low-temperature liquid nitrogen adsorption experiments of coal samples from three typical mines in northern Guizhou were carried out. Pore structure parameters were studied, including specific surface area, pore volume, average pore diameter, most probable pore diameter and fractal dimension, and gas diffusion pattern in pores was analyzed. Finally, impacts of pore characteristic parameters on adsorption capacity and emission performance was discussed. The results show that outburst coal's pores are relatively developed with pore permeability, and gas in pores mainly emits in transitional and Fick diffusion types. Compared with temperature, pressure and pore diameter have a more significant effect on Knudsen number. It is also found that pore characteristic parameters maintain a good linear relation with initial diffusion velocity of gas, and fractal characteristics of coal pore are evident. Adsorption capacity are quadratic function increasing while initial diffusion velocity of gas increases linearly with fractal dimension.

Key words: outburst coal, pore structure, Kundsen number, fractal dimension, adsorption capacity, emission performance

CLC Number:

X936

CHEN Liuyu, LI Xijian, SHEN Zhonghui, BI Juan, LIU Yu, XU Shiqing. Pore structure and fractal characteristics of outburst coal in northern Guizhou[J]. China Safety Science Journal, 2020, 30(2): 66-72.

References 16

[1]	ALEXEEV A D, VASILENKO T A, ULYANOVA E V. Closed porosity in fossil coals [J]. Fuel, 1999, 78(6):635-638.
[2]	李祥春,聂百胜,何学秋. 振动诱发煤与瓦斯突出的机理[J].北京科技大学学报,2011,33(2): 149-152.LI Xiangchun, NIE Baisheng, HE Xueqiu. Mechanism of coal and gas bursts caused by vibration [J]. Journal of University of Science and Technology Beijing, 2011, 33(2):149-152.
[3]	李希建,林柏泉,施天虎. 贵州典型矿区突出煤孔隙结构及其吸附特性实验研究[J]. 采矿与安全工程学报,2013,30(3): 415-419.LI Xijian, LIN Baiquan, SHI Tianhu. Experiment study on pore structures of outbrust coal and its adsorption at typical mining fields in Guizhou province [J]. Journal of Mining and Safety Engineering, 2013, 30 (3):415-419.
[4]	林海飞,程博,李树刚,等. 煤的吸附孔结构对瓦斯放散特性影响的实验研究[J]. 采矿与安全工程学报,2016,33(3): 557-563.LIN Haifei,CHENG Bo,LI Shugang,et al. Experimental study on the effect of adsorption pore structure on gas emission characteristics [J]. Journal of Mining and SafetyEngineering, 2016, 33 (3):557-563.
[5]	何学秋,聂百胜. 孔隙气体在煤层中扩散的机理[J]. 中国矿业大学学报,2001,30(1): 1-4.HE Xueqiu, NIE Baisheng. Diffusion mechanism of porous gases in coal seams [J]. Journal of China University of Mining and Technology, 2001, 30(1):1-4.
[6]	聂百胜,伦嘉云,王科迪,等. 煤储层纳米孔隙结构及其瓦斯扩散特征[J]. 地球科学,2018,43(5): 1 755-1 762.NIE Baisheng, LUN Jiayun, WANG Kedi, et al. Characteristics of nanometer pore structure in coal reservoirs [J]. Earth Sciences, 2018, 43(5): 1 755-1 762.
[7]	富向,王魁军,杨天鸿. 构造煤的瓦斯放散特征[J].煤炭学报,2008,33(7): 775-779.FU Xiang, WANG Kuijun, YANG Tianhong. Gas irradiation feature of tectonic coal [J]. Journal of China Coal Society, 2008, 33(7):775-779.
[8]	李子文,郝志勇,庞源,等. 煤的分形维数及其对瓦斯吸附的影响[J]. 煤炭学报,2015,40(4): 863-869.LI Ziwen, HAO Zhiyong, PANG Yuan, et al. Fractal dimensions of coal and their influence on methane adsorption [J]. Journal of China Coal Society, 2015, 40(4):863-869.
[9]	赵迪斐,郭英海,毛潇潇,等. 基于压汞、氮气吸附与FE-SEM的无烟煤微纳米孔特征[J]. 煤炭学报,2017,42(6): 1 517-1 526.ZHAO Difei, GUO Yinghai, MAO Xiaoxiao, et al. Characteristics of macro-nanopores in anthracite coal based on mercury injection,nitrogen adsorption and FE SEM [J]. Journal of China Coal Society, 2017, 42(6):1 517-1 526.
[10]	宋晓夏,唐跃刚,李伟,等. 中梁山南矿构造煤吸附孔分形特征[J]. 煤炭学报,2013,38(1): 134-139.SONG Xiaoxia, TANG Yuegang, LI Wei, et al. Fractal characteristics of adsorption pores of tectonic coal from Zhongliangshan southern coalmine [J]. Journal of China Coal Society, 2013, 38(1):134-139.
[11]	彭鑫,江泽标,李波波,等. 二氧化碳致裂对煤岩孔隙表面分形特征影响实验研究[J]. 中国安全生产科学技术,2019,15(2): 111-117.PENG Xin,JIANG Zebiao,LI Bobo,et al. Experimental study on influence of CO2 cracking on surface fractal characteristics of coal pore [J]. Journal of Safety Science and Technology, 2019, 15(2):111-117.
[12]	陈刘瑜,李希建,毕娟,等. 黔北构造煤与原生结构煤解吸初期特征研究[J]. 煤炭科学技术,2019,47(2): 107-113.CHEN Liuyu, LI Xijian, BI Juan, et al. Study on characteristics of initial desorption of tectonic coal and primary structural coal in northern Guizhou [J]. Coal Science and Technology, 2019, 47(2):107-113.
[13]	李希建,沈仲辉,刘钰. 黔西北构造煤与原生结构煤孔隙结构对吸解特性影响实验研究[J]. 采矿与安全工程学报,2017,34(1): 170-176.LI Xijian, SHEN Zhonghui, LIU Yu. The experimental research on the impact of porestructure in tectonic coal and primary structure coal on gas adsorption-desorption [J]. Journal of Mining and Safety Engineering, 2017, 34(1):170-176.
[14]	BUDAEVA A D,ZOLTOEV E V. Porous structure and sorption properties of nitrogen-containing activated carbon [J]. Fuel, 2010, 89(9):2 623-2 627.
[15]	RIGBY S P.Predicting surface diffusivities of molecules from equilibrium adsorption isotherms [J]. Colloids and Surfaces A Physicochemical and Engineering Aspects, 2005, 262(1):139-149.
[16]	闫江伟,薄增钦,杨亚磊. 纳米级孔隙对构造煤吸附瓦斯能力的影响[J]. 中国安全科学学报,2018,28(10): 131-136.YAN Jiangwei, BO Zengqin, YANG Yalei. Influence of nanoscale pore on gas adsorption capacity of deformed coal [J]. China Safety Science Journal, 2018,28(10):131-136.