Investigation of adsorption characteristics of C2H4 from coal in low-temperature stage
In order to study the evolution characteristics of adsorption of C2H4 by residual coal in closed area of coal mine goaf,taking non-cohesive coal in Lingxin Coal Mine of Ningxia as the research object,the adsorption of C2H4 by coal was tested by volumetric method.The effects of temperature,pressure and particle size on the adsorption capacity,adsorption rate and adsorption thermodynamics were analyzed.The results show that when the temperature is 30-60℃,the pressure is 0.15-0.45 MPa and the particle size is 20-120 mesh,the adsorption capacity of C2H4 increases with the decrease of temperature,the increase of pressure and the decrease of particle size.The adsorption process changes from fast to slow with time,then tends to equilibrium,and the adsorption rate rapidly tends to 0.When the temperature and particle size are constant,the adsorption rate increases with the increase of equilibrium pressure.When the temperature and pressure are constant,the adsorption rate increases with the decrease of particle size.At the same adsorption capacity,the smaller the particle size is,the lower the equilibrium adsorption heat is.The equivalent adsorption heat of C2H4 adsorbed by coal samples with different particle sizes is 0.69-40.23 kJ/mol,which belongs to physical adsorption.The pressure correction coefficient is introduced to fit,and the pressure and particle size are proportional to the reduction of adsorption free energy when the temperature is constant.Under the condition of constant particle size,the temperature is inversely proportional to the decrease of adsorption free energy.The adsorption entropy of C2H4 for coal samples with different particle sizes is negative,and the adsorption entropy increases with the increase of adsorption capacity and the decrease of temperature.Under the same adsorption capacity,the larger the particle size,the greater the adsorption entropy.
low temperature stageC2H4adsorption characteristicsadsorption ratespontaneous combustion of coaladsorption heat
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