Density Distributions and CO2 Sorption in a Confined Coal Sample for Carbon Sequestration

Jikich, Sinisha A.¹, Robert McLendon², Duane H. Smith² (1) National Energy Technology Laboratory/Parsons, Morgantown, WV (2) National Energy Technology Laboratory/U.S. DOE, Morgantown,

A confined core of a Pittsburgh #8 coal obtained from a mine near Waynesburg, Pennsylvania, has been investigated using computerized tomography. The 3-D density distribution of the coal was calculated for the stressed and confined core with, and without CO2 sorption. We used a dual energy technique to quantify volumetric variations in bulk density and effective atomic number. CO2 sorption of coal was then investigated at predetermined injection pressures. The density changes in the coal matrix were calculated and correlated with the CO2 adsorbed for a multitude of regions of interest (ROI) chosen in slices perpendicular to the bedding plane. The results show that even in small core samples, coal heterogeneity is high. Large variation of density was observed in small regions of interest compared to the average density of slices. Also, the coal density distribution was changed significantly due to the CO2 uptake. This technique seems very useful in calculating density distribution for stressed and confined coal samples and the change in volumetric density distribution due to CO2 adsorption. Furthermore the kinetics of heterogeneous adsorption and swelling in coal can be determined.