Research on fractal characteristics of coal freezing with low temperature liquid nitrogen using nitrogen adsorption method and mercury intrusion method

被引：0
|
作者：
Qin L. [1 ,2 ]
Wang P. [1 ,2 ]
Zhai C. [3 ]
Li S. [1 ,2 ]
Lin H. [1 ,2 ]
Long H. [1 ,2 ]
机构：
[1] College of Safety Science and Engineering, Xi'an University of Science and Technology, Shaanxi, Xi'an
[2] Key Laboratory of Western Mine Exploitation and Hazard Prevention, Ministry of Education, Xi'an University of Science and Technology, Shaanxi, Xi'an
[3] School of Safety Engineering, China University of Mining and Technology, Jiangsu, Xuzhou
来源：
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | 2023年 / 40卷 / 01期
关键词：
cyclic freezing; fractal dimension; joint characterization; mercury intrusion; nitrogen adsorption;
D O I：
10.13545/j.cnki.jmse.2021.0623
中图分类号：
学科分类号：
摘要：
Liquid nitrogen freezing is an effective method to achieve coal pore penetration and improve coalbed methane extraction. To quantitatively study the pore structure characteristics of low-temperature liquid nitrogen frozen coal, the self-developed liquid nitrogen frozen coal test platform was used to conduct the single freezing and cyclic freezing tests for lignite, respectively. The pore transformation law of coal in the process of liquid nitrogen freezing was examined by the high-pressure adsorption instrument and mercury injection instrument, and the pore fractal dimension of liquid nitrogen frozen coal was analyzed. The test results showed that after liquid nitrogen freezing, the nitrogen adsorption capacity and a mercury input capacity of coal increased. The increased rates of nitrogen adsorption capacity and mercury input capacity of circulating frozen coal were 1.08 times and 1.62 times that of single frozen coal, respectively. D1 (fractal dimension of seepage hole) and D2 (fractal dimension of adsorption hole) were ranging between 2-3, showing significant pore fractal characteristics. D1 and D2 decreased along with the increase of absolute freezing time, indicating an enhanced permeability of pores and a reduced complexity of internal structure. The reduction of the fractal dimension of circulating frozen coal was greater than that of single frozen coal. D1 / D2 was positively correlated with the freezing time of absolute liquid nitrogen. The growth rate of circulating freezing D1/ D2 was 2.06 times of the single freezing D1/ D2. © 2023 China University of Mining and Technology. All rights reserved.
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页码：184 / 193and203
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