| Taking a self-developed large-scale simulation system for the platform, properties of adsorption on coal CH4 and CO2 were studied based on literature review and experimental research, and meanwhile,studied the influence law of adsorption on coal permeability. Finally made indoor simulation experiment of driving CH4 by CO2 gas injection, mainly got the following conclusions:Langmuir equation can be used to describe the adsorption of CO2 and CH4 on coal,There is a relationship between Langmuir constant a and temperature T, and it can be indicated by the expression of a=a0+AeBTFor the same coal sample, under the same temperature conditions,The results show that the greater adsorption is,the coal permeability becomes smaller. After adsorption,the permeability of coal significantly reduced, compared with before adsorption.There is a significant lag effect of adsorption and desorption on gas, the gas pressure changes more rapidly in the process of CO2 adsorption on coal than CH4 adsorption;After the injection of CO2,compared with methane single desorption,In an early stage, speed and amount of methane single desorption are greater than the speed and amount of displacement desorption,it is that the free gas was desorbed first as time flies,displacement desorption was at an advantage,and the speed and amount of displacement desorption become greater.In the process of replacement, methane concentration is declining, while CO2 levels rise.In the process of gas injection,the temperature of coal have been significantly increased,it is more beneficial to make CH4 gas molecules become free from the adsorbed state when temperature increases.Under the presure step-down at the same rate,Useing the method of displacement desorption, compared with the method of conventional presure step-down,desorption rate of CH4 can be raised about 2.12 times,at the same time,a lot of greenhouse gas CO2 will also buried in the ground, there is a significant environmental benefit.Figure [41] table [11] reference [86]... |
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