Study On Adsorption Characteristics And Mechanism Of Gas Storage Of Anthracite In Chengzhuan Mine Coal

Our country has rich coal resources, at the same time, the reserves of CBM isvery large,and CBM is a kind of clean energy. Development of CBM canalleviate the pressure of the demand for energy、reducing our dependence onimported oil and the emissions of greenhouse gas. But in coal mining, accidentof the highlight and explosion casualties caused by methane are occurredfrequently. CBM mainly exist in adsorption state, therefore, the research of coalbed methane adsorption characteristics、mechanism of coal and gas are hasimportant significance on energy、defense、environment and mine safety.To study temperature、 pressure and particle size’s influence on theabsorption characteristics of the coal、the applicability of adsorption model andmechanism of gas storage, anthracite of9#coal seam in Cheng Zhuang coalmine was selected as the study object. The analysis of the above issues wascompleted with isothermal adsorption experiment、 predecessors’achievements for reference and based on the mine gas prevention and control、physical chemistry、statistical thermodynamics、 surface physical chemistry、 the fractal theory and et al. Getting the following conclusion:1）temperature、 particle size、pore volume and gas properties all will affectadsorption quantity. The increase of elevated temperature、 particle size andreducing the pore volume all will result in adsorption decrease; The higher thetemperature、the smaller particle size and the smaller volume, this decline isthe more obvious; Anthracite has the most adsorption quantity of carbondioxide and oxygen is the ministry.2）Nature of the gas and temperature both have effect on the modelapplicability, but coal sample size has no influence on the applicability of themodel. The Langmuir model or DR model have high fitting precision ofexperimental data under supercritical condition. The BET model should be usedwhen the experiment temperature is below theoretical temperature; TheLangmuir model has the best fitting precision and the BET model has thepoorest fitting precision when the oxygen adsorption experiment data ofanthracite is needed to fitted.3）The difference of inter-atomic forces was caused by the susceptibilitydifferences between methane、oxygen、carbon dioxide. The stronger themolecular inter-atomic forces, the greater the stability of the adsorption, andthe adsorption capacity is larger; Orientation force and the molecularinter-atomic forces are both decreases as the temperature increases.4）The influence of temperature on the adsorption can be quantified withthe adsorption heat and surface free energy. Adsorption heat is calculated by Clausius-Clapeyon equation combined with classical adsorption model, but theadsorption gas should be settled as the ideal gas. To guarantee the correctnessof the calculation results, the fugacity in chemical thermodynamics wasintroduced.5）The fractal formula of pore volume and surface were derivated on thebasis of the Menger model, and the fractal formula shown that the porevolume and surface area of coal both have obvious fractal characters.Therefore, the influences of pore volume and specific surface area onadsorption were unified to the similar dimension D.