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The objective of this work is to study the gas desorption characteristics of the high-rank intact coal and fractured coal.The gas adsorption,mercury porosimetry and gas desorption experiments were carried out in this study.Then,the theories of thermodynamics,diffusion mechanism and desorption kinetics were used to estimate the gas desorption characteristics.The results of gas adsorption experiments show that the initial isosteric adsorption heat of the intact coal is greater than that of the fractured coal,indicating that the gas molecules desorb more easily from fractured coal than intact coal.Using the mercury porosimetry,we find that the diffusion channels of fractured coal are more developed than those of intact coal.The difficult diffusion form dominates in the intact coal during the gas diffusing,while the easy diffusion form dominates in the fractured coal.The results of gas desorption experiments show that the initial gas desorption volume and velocity of the fractured coal are both greater than those of the intact coal.Using the Fick diffusion law,the study calculates the gas diffusion coefficients of the intact coal and fractured coal.The diffusion coefficients of the fractured coal are 2 times and 10 times greater than those of the intact coal at the time of 0-120 and 0-10 min,respectively.
The objective of this work is to study the gas desorption characteristics of the high-rank intact coal and fractured coal. The gas adsorption, mercury porosimetry and gas desorption experiments were carried out in this study. Chen, the theories of thermodynamics, diffusion mechanism and desorption kinetics were used to estimate the gas desorption characteristics.The results of gas adsorption experiments show that the initial isosteric adsorption heat of the intact coal is greater than that of the fractured coal, indicating that the gas molecules desorb more easily from fractured coal than intact coal. Using the mercury porosimetry, we find that the diffusion channels of fractured coal are more than those of intact coal. The difficult diffusion form dominates in the intact coal during the gas diffusing, while the easy diffusion form dominates in the fractured coal. The results of gas desorption experiments show that the initial gas desorption volume and velocity of the fractured coal are both greater than those of the intact coal. Using the Fick diffusion law, the study calculates the gas diffusion coefficients of the intact coal and fractured coal. The diffusion coefficients of the fractured coal are 2 times and 10 times greater than those of the intact coal at the time of 0-120 and 0-10 min, respectively.