Comparative Study Of CH₄and CO₂Adsorption-desorption Characteristics

The paper use the methods of experimental study and theoretical analysis, Analysis ofthe coal samplings material composition and basic characteristics which have taken fromBinchang mining areas，producing cylinder raw coal sampling and moisture balance coalsampling by self. Then, basing on the coal adsorption/desorption CH4and CO2experiments,contrast the adsorption-desorption characteristics and thermodynamic characteristics of coalon the two gases, on the basis of adsorption potential theory, drawing of CH4and CO2adsorption on coal characteristic curves, Getting the relationship between adsorption andadsorption potential space of CH4and CO2adsorption on coal, theoretical study on initialand basic characteristics of injecting CO2to improve coal-bed methane CH4.The results show that the genus of Binchang mining areas coalbed is low rank coal. Coalpore is dominated by micro-and small holes, which have large specific surface area, is theexcellent forum of coalbed methane adsorption and reservoir; adsorption of coal samplesunder the same conditions as for CO2adsorption capacity is much higher than the amount ofCH4absorption, it indicates that the adsorption ability of coal CO2is stronger than CH4;discussion of adsorption thermodynamics parameters, more in-depth studies on mechanism ofthe coal adsorbing CH4and CO2,under the same conditions, limiting adsorption heat of thecoal adsorbing CO2generally greater than adsorbing CH4,it reflects the coal much closer toCO2;the characteristic curves of the coal adsorbing CH4and CO2reflect, under the highpressure condition, CO2adsorption on coal adsorption potential is far greater than CH4,injectting CO2enhance coalbed CH4production which can receive good results, under lowpressure conditions, it has less effective.Through this paper research, making Isothermal adsorption/desorption combination withadsorption thermodynamics and adsorption potential theory, further enriches the study onmechanism of coal adsorbing gas, which provides a theoretical basis for the selected area determines injection pressure and adapted object in injectting CO2enhance CH4productiontechnology.