Title: Effect of supercritical CO₂ on various rank coals: implications for CO₂ sequestration in coal seams with enhanced coalbed methane recovery

Authors: Zhicong Wei; Chen Xue; Yingbo Mao; Jianjun Fang

Addresses: State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China ' State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China ' College of Science, Honghe University, Mengzi 661199, China ' State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China

Abstract: Sequestration of CO₂ in coal seams with enhanced coalbed methane recovery (CO₂-ECBM) can mitigate CO₂ emissions. In this work, the effects of the supercritical CO₂ fluid on the physicochemical property of coals were elucidated. The results show that CO₂ interaction can mobilise the volatile hydrocarbons in the coal matrix and subsequently result in the decrease of volatile matter content. The volatile matter contents of coals decrease with temperature, pressure and injection rate of CO₂ interaction. The extracted volatile matters are of biological toxicity, thus CO₂-ECBM process should be operated at the optimum temperature, pressure and CO₂ injection rate. The moisture contents of Zhangji coal and Liulin coal after CO₂ interaction increase which implies that the pore morphology of the above two coals grows up. For low rank Bulianta coal and high rank Qinshui coal, the swelling effect induced by CO₂ is dominant. Thus, the moisture content after CO₂ interaction decreases in comparison with the raw state.

Keywords: CO₂ sequestration; coal; supercritical fluid extraction; swelling.

DOI: 10.1504/IJGW.2018.092899

International Journal of Global Warming, 2018 Vol.15 No.2, pp.109 - 122

Received: 02 May 2016
Accepted: 30 Jan 2017
Published online: 02 Jul 2018 *

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