Title: Effects of ambient pressure on diffusion kinetics in coal during methane desorption

Authors: Bing Zhang; Hanpeng Wang; Liang Yuan; Zhongzhong Liu; Yuqiang Zhang; Shucai Li; Junhua Xue; Shugang Wang

Addresses: Research Centre of Geotechnical and Structural Engineering, Shandong University, Jinan, 250061, China ' Research Centre of Geotechnical and Structural Engineering, Shandong University, Jinan, 250061, China ' Research Centre of Geotechnical and Structural Engineering, Shandong University, Jinan, 250061, China; Faculty of Safety Engineering, China University of Mining and Technology, Xuzhou, 221116, China ' Research Centre of Geotechnical and Structural Engineering, Shandong University, Jinan, 250061, China ' Research Centre of Geotechnical and Structural Engineering, Shandong University, Jinan, 250061, China ' Research Centre of Geotechnical and Structural Engineering, Shandong University, Jinan, 250061, China ' National Engineering Research Institute of Coal Mining, Huainan mining (Group) Co., Ltd., Huainan, 232002, China ' Research Centre of Geotechnical and Structural Engineering, Shandong University, Jinan, 250061, China

Abstract: To elucidate the influence of ambient pressure on diffusion kinetics during gas desorption, which is of great significance to the efficient development of coalbed methane, a methane desorption experiment was carried out on coal particles under different ambient pressures, and diffusion coefficients for each test time were solved by the unipore diffusion model. The experiment was carried out using our independently developed 'coal particle methane desorption meter' to overcome the difficulty that the existing equipment could not achieve a constant ambient pressure higher than atmospheric pressure. The results show that during methane desorption in coal particles, the diffusion coefficient was not constant but gradually decreased with time, showing a power function relationship. In addition, the diffusion coefficient decreased linearly with increasing ambient pressure, and the degree of influence was related to time. This research will play an important role in improving the unipore diffusion model and elucidating the gas production mechanisms. [Received: February 2, 2018; Accepted: May 9, 2018]

Keywords: coal particle; methane desorption; ambient pressure; desorption time; diffusion kinetics; diffusion coefficient; coalbed methane; unipore diffusion model.

DOI: 10.1504/IJOGCT.2020.107550

International Journal of Oil, Gas and Coal Technology, 2020 Vol.24 No.3, pp.426 - 443

Received: 02 Feb 2018
Accepted: 05 Sep 2018
Published online: 01 Jun 2020 *

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