煤吸附解吸CO2变形特征的试验研究

无商业开采价值的煤层被认为是理想的CO2储存场所，煤吸附解吸CO2的变形特征是煤中CO2封存的重要问题。利用煤体吸附-解吸变形试验系统，在预定压力的CO2气体环境下，对取自赵各庄煤矿9号煤层煤样的轴向应变和径向应变进行了近600 h的观测，研究煤样在不同气体压力下吸附、解吸CO2的变形特征。实验结果显示：煤样吸附/解吸CO2产生的膨胀/收缩变形，煤样吸附变形需要12 h甚至更长时间才能趋于稳定，原煤样品的吸附解吸变形呈各向异性；经历了吸附和解吸CO2的煤样均有不同程度的残余变形，气体压力低于1.5 MPa时残余体积应变低于0.6×10-3，可近似认为煤样吸附解吸变形过程可逆。通过煤样吸附解吸变形实验数据的拟合发现，Langmuir方程可反映煤样吸附解吸CO2变形随气体压力的变化规律。

Experimental study of coal strain induced by carbon dioxide sorption/desorption

Unminable coal beds have been recommended as good CO2 sequestration.Coal strain due to sorption/desorption of CO2 is an important issue on carbon dioxide sequestration.To investigate CO2 sorption/desorption induced coal strain，coal axial and radial strains under gas hydrostatic pressure were measured for nearly 600 hours by means of test system for sorption-induced strain.The coal samples were from No.9 coal seam in Zhaogezhuang Mine.The experimental results indicate that coal swells when adsorbing CO2，shrinks when desorbing CO2.The sorption/desorption process is very slow and it takes 12 hours or even longer for the sorption-induced strain to stabilize.The coal strain due to sorption/desorption CO2 is anisotropy.Coal samples have different levels of residual deformation after a cycle of sorption and desorption.When gas pressure is less than 1.5 MPa，coal residual volumetric strain undergoing a cycle of sorption and desorption is less than 0.6 × 10-3.It is reasonable to consider that the process of coal deformation induced by adsorption and desorption is reversible.The fitting results of coal adsorption/desorption experimental data show that Langmuir equation is suitable to describe coal adsorption/desorption strain variation with CO2 gas pressure.