Impact of Diverse Parameters on CO2 Adsorption in CO2 Sequestration: Utilizing a Novel Triaxial Testing Apparatus

Abstract

In order to minimize greenhouse gas emissions, it is essential from an environmental point of view to employ CO₂ sequestration technology to store CO₂ in underground coal layers. To study this strategy, a triaxial testing apparatus is required. This study introduces a novel triaxial testing apparatus developed to explore enhanced coal bed methane (ECBM) and carbon dioxide (CO₂) sequestration techniques. Several laboratory tests were conducted to validate the apparatus and study the behavior of coal exposed to CO₂ using this machine. In fact, the implementation of this machine marks the initial step in an empirical feasibility analysis of CO₂ sequestration in Iranian coal seams. This analysis involves examining the impact of ash content, ambient temperature, and saturation direction on CO₂ adsorption and emission in various coal samples. Two different thermal coal samples from Chamestan and Tash mines were utilized. Some results, such as the trend of the coal sample's strain, show good correlation with previous work. Additionally, some results presented in this work are novel. On the basis of the results, the developed apparatus demonstrated satisfactory performance, and its innovative design fully meets the desired outcome. Higher ash content increases coal strength and reduces deformation. Lower ash content leads to more gas adsorption and deformation post-saturation. Gas adsorption is higher at 25°C than at 4°C. Moreover, coal samples at 25°C had 12.5 times more axial strain than those at 4°C. Lateral saturation causes 13.72% larger axial strain changes than top and end saturation due to increased gas-sample contact and penetration into the coal matrix.