Experimental Study on Influencing Factors and Thermal Effects of CO2 Adsorption by Coal

The utilization of CO2 is extremely importantto solvethe environmental problems and coal spontaneous combustion in goaf.There are three kinds of CO2 utilization in goaf: adsorption,diffusion, and seepage. Since adsorption will consume CO2 in goaf, the optimization of CO2 injection amount isvery critical. A self-developed adsorption experimental device wasused to determine the CO2 adsorption capacity of threedifferent particle sizes of lignite coal samples at 30-60 degrees Cand 0.1-0.7 MPa. The factors affecting CO2 adsorptionby coal and its thermal effect were studied. In the coal and CO2 system, the CO2 adsorption characteristic curveis not affected by temperature, but there are differences in thatwith different particle sizes. The adsorption capacity increases withthe increase of pressure, while it decreases with the increase oftemperature and particle size. Under atmospheric pressure, the adsorptioncapacity of coal is a logistic function relationship with temperature.Furthermore, the average adsorption heat of CO2 on ligniteshows that the interaction force between CO2 moleculeshas a stronger effect on CO2 adsorption than the effectof heterogeneity and anisotropy on the coal surface. Finally, theexisting gas injection equation is improved theoretically with CO2 dissipation, which provides a new idea for the work of CO2 prevention and fire suppression in goaf.