Experimental Study On Gas Adsorption And Desorption Of Coal Under Different Temperature And Pressure Conditions

Coal is the main energy source in China,and coal and coalbed methane are abundant.Coalbed methane is usually referred to as gas gas,which usually exists on the surface of micropore coal wall in adsorption state,or in free state and dissolved state in coal seam.Although coalbed methane is a clean natural resource,it is also a kind of harmful gas,causing many coal mine disasters,such as gas explosion,suffocation,outburst and so on.It is of great significance to study the influence law of coal adsorption and desorption gas for mastering the mechanism of coal adsorption and desorption gas,the exploitation and utilization of coalbed methane,and the prevention and control of coal mine gas disasters.This paper makes an industrial analysis on the coal body of 22301 working face in Tunlan coal mine,The moisture content is 0.22%,the ash content is 16.44%,the volatile content is 26.67%,and the sulfur content is 0.45%.In this experiment,bsd-ph series of3h-2000 ph automatic high-pressure gas analysis system produced by beishide Instrument Technology(Beijing)Co.,Ltd.was used for research.Experimental study on gas adsorption and desorption of coal under different cycle time,pressure,temperature and particle size was carried out.Research shows:(1)The adsorption capacity and concentration of methane increase with the increase of gas pressure.When the gas pressure increases to a certain extent,the adsorption capacity and concentration curve of methane gradually flatten;when the gas pressure decreases,the methane is desorbed.(2)The equilibrium time(1 h)and maximum time(2 h)set at each partial pressure point of different cycle step time have met the experimental requirements,and the degassing time of the scheme is 3 h;(3)the Langmuir adsorption isotherm and Freundlich adsorption isotherm of different pressure,temperature and particle size fit well,and it is found that the slope and intercept of Langmuir isotherm of different pressure change with the increase of upper limit pressure The results show that the slope of Langmuir fitting equation decreases,while the intercept increases gradually;the overall reaction of Langmuir isothermal curve is that P / V value is positively correlated with temperature except for partial dispersion of experimental results in the second half of 200 mesh at different temperatures;the gas pressure P and P / V of different particle sizes meet a good linear relationship,and the fitting coefficient is above 0.9000.(4)The maximum gas pressure under different pressures is positively correlated with the adsorption constant a and negatively correlated with the adsorption constant B;the adsorption constants A and B are negatively correlated with the temperature under the conditions of different temperatures,different gas pressures and sample particle sizes;in general,the larger the particle size of coal sample is,the larger the adsorption constant a is,and the relationship between the adsorption constant B and the sample particle size is uncertain(5)Under different pressures,the adsorption strength n and adsorption constant k are positively correlated with the maximum upper limit gas pressure,and the fitting accuracy is as high as 0.99;under different temperatures,the adsorption strength n and adsorption constant k are negatively correlated with temperature;the adsorption strength n and adsorption constant k of samples with different particle sizes > 200 mesh are greater than the relevant parameters of samples with 60-80 mesh to varying degrees.The influence of sample size on adsorption strength n and adsorption constant k is relatively small.(6)The desorption characteristics and parameters of different pressure,temperature and particle size were obtained.It is hoped that the experimental results can provide data support for the exploitation and prevention of coalbed methane and mine gas.