Title: Fractal analysis of pore characteristics and their impacts on methane adsorption of coals from Northern China

Authors: Ziwen Li; Baiquan Lin; Yabin Gao; Zhaodan Cao; Yanying Cheng; Junyang Yu

Addresses: School of Safety Engineering, State Key Laboratory of Coal Resources and Mine Safety, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China ' School of Safety Engineering, State Key Laboratory of Coal Resources and Mine Safety, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China ' School of Safety Engineering, State Key Laboratory of Coal Resources and Mine Safety, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China ' School of Safety Engineering, State Key Laboratory of Coal Resources and Mine Safety, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China ' School of Safety Engineering, State Key Laboratory of Coal Resources and Mine Safety, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China ' School of Safety Engineering, State Key Laboratory of Coal Resources and Mine Safety, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China

Abstract: To better understand the pore characteristics of coal and their impacts on methane adsorption, we have conducted fractal analyses on eight coal samples from Northern China. Results show that the two fractal dimensions have different impact on methane adsorption: D₁ has a positive effect on Langmuir volume while D₂ has an opposite effect. Langmuir pressure P_l decreases with increasing D₁, however, there is no relationship between P_l and D₂. The relationships between pore size distribution and methane adsorption show that both transitional pores and micropores are favourable for methane adsorption reflected in the positive effects on Langmuir volume V_l while only micropores especially pores with diameter smaller than 1.5 nm have significant influence on Langmuir pressure P_l. The relationship between coal rank and Langmuir volume V_l is characterised by a U-shaped curve, with minimum values at medium coal rank (1.0 < R_o,max < 1.5), whereas the Langmuir pressure P_l decreases with increasing coal rank. [Received: June 24, 2013; Accepted: February 19, 2014]

Keywords: fractal dimension; methane adsorption; Langmuir volume; Langmuir pressure; coal rank; pore characteristics; fractal analysis; China; pore size distribution; transitional pores; micropores; coalbed methane; CBM; coal mining.

DOI: 10.1504/IJOGCT.2015.071507

International Journal of Oil, Gas and Coal Technology, 2015 Vol.10 No.3, pp.306 - 324

Received: 27 Jun 2013
Accepted: 19 Feb 2014
Published online: 31 Aug 2015 *

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