Swelling of coal in carbon dioxide, methane and their mixtures

Swelling and acoustic emission behaviour of unconfined and confined coal during sorption of CO2

“…Day et al, 2008Day et al, , 2010Day et al, , 2011Day et al, , 2012Durucan and Shi, 2009;Majewska and Ziętek, 2007;van Bergen et al, 2009). However, so far, there have been only a limited number of experimental studies on the sorption of gas by constrained coal (Czapliński et al, 1986;Hol et al, 2011;Jikich et al, 2009;Pone et al, 2009a,b;Ranjith et al, 2010;Wang et al, 2010Wang et al, , 2011.…”

“…Much effort has been put into studying a number of issues related to CO 2 sequestration and enhanced coalbed methane production from unminable coal seams (Bae and Bhatia, 2006;Busch et al, 2003Busch et al, , 2006Bustin et al, 2008;Ceglarska-Stefańska and Czapliński, 1993;Cui et al, 2007;Day et al, 2008Day et al, , 2010Day et al, , 2011Day et al, , 2012Fitzgerald et al, 2005;Goodman et al, 2006;Harpalani and Chen, 1995;Karacan, 2003Karacan, , 2007Keleman and Kwiatek, 2009;Larsen, 2004;Larsen et al, 1997;Majewska et al, , 2009Majewska et al, , 2010Mazumder et al, 2006a,b;Ozdemir et al, 2004;Pan et al, 2010;Pone et al, 2009a,b;Reucroft and Patel, 1986;Reucroft and Sethurman, 1987;Robertson, 2005;St. George and Bakarat, 2001;Zarębska and Ceglarska-Stefańska, 2008).…”

Thermodynamic models for swelling of unconfined coal due to adsorption of mixed gases

“…Focusing on the swelling response to mixed gas sorption, Day et al [14] recently reported measurements performed on four Australian coals, exposed to CO 2 , methane and mixtures of the two. Measurements were made on laterally unconstrained (i.e.…”

“…Note that n ab s is the number out of all adsorption sites fully accessible to a and b, C i s is the concentration of available adsorption sites accessible to component i in mole per kg coal, K i is the equilibrium constant for the adsorption process of species i, a i g is the activity of the free gas/fluid species i. not adsorb, the CO 2 was completely displaced by helium, causing the coal to shrink to its original dimensions. On this basis, Day et al [14] proposed that CH 4 and CO 2 have similar access to all adsorption sites, and that the swelling behaviour of the coal studied is determined solely by the partial pressures of the sorbing gases, with no selective sorption effects. In these experiments, the swelling strains developed upon exposure to CH 4 -CO 2 mixtures were linearly dependent on CO 2 mole percentage.…”

“…This exchange, or preferential adsorption effect, is considered to be due to either the reduction of CH 4 partial pressure as CO 2 penetrates the system or to truly selective adsorption of CO 2 over CH 4 [2]. The resulting partial replacement of CH 4 by CO 2 leads to net swelling, reflecting equilibration with respect to the new composition of the gas/fluid mixture present in the coal seam [2,14].…”