Experimental Study On Gas Sorption Kinetics Of Briquette Under Different Conditions

The prevention and control of mine gas disaster is one of the key points of coal and gas safety co-production,which is inseparable from the microstructure characteristics of coal and the law of gas adsorption.Through the NMR(Nuclear Magnetic Resonance)and volumetric gas adsorption experiments,the paper studied the effects of molding pressure and particle size on the pore structure and gas adsorption characteristics of briquette,and carried out theoretical analysis.The experiment used nuclear magnetic resonance to obtain nuclear magnetic resonance T2 spectrum.The experiment shows that the briquette mainly presents two peaks of micropores and medium pores.The inter-particle gap,the degree of particle breakage and the density of the briquettes of different particle sizes and molding pressures are different,and the internal structure exhibits individual differences.This causes a change in the pore specific surface area of the briquette,which is manifested by the difference in NMR relaxation time and signal amplitude.The area and ratio of micropore peak are inversely proportional to particle size and proportional to molding pressure.The peak area and proportion of the large pores and the total pores are proportional to the particle size and inversely proportional to the molding pressure.According to the results of the high pressure gas adsorption experiment of the volumetric method,the gas adsorption amount of the briquette changes into pressure.In the single factor experiment,the gas adsorption capacity of the briquette is inversely proportional to the adsorption temperature,the coal particle size and the molding pressure.Fitting the adsorption isotherm and choose the theoretical model that is suitable for describing the adsorption law of coal briquettes.The adsorption constant a is relatively small,indicating that the adsorption capacity of the briquette is weak,and the adsorption constant a value is inversely proportional to the adsorption temperature,the coal particle size,and the molding pressure.According to the experimental results of the atmospheric pressure gas adsorption by the volumetric method,the gas adsorption capacity of the briquette increases to time,and the growth rate gradually slows down until the adsorption dynamic equilibrium is reached.The experiment analyzes the sensitivity of atmospheric pressure gas adsorption amount of temperature,particle size and molding pressure,and finds that temperature is the main factor and the rest are secondary factors.Fitting the adsorption isotherm under normal pressure,choose the theoretical model that is suitable for describing the adsorption kinetics of briquette.The relative error between the equilibrium adsorption amount and the actual equilibrium adsorption amount obtained by fitting the quasi-first-order kinetic model is the smallest,but the calculated value is slightly lower than the actual value.The parameters of reaction adsorption rate of the four models are positively correlated with temperature,negatively correlated with particle size,and the correlation law with molding pressure is not obvious.Studying the pore structures characteristics and gas adsorption characteristics of briquette under different forming conditions have engineering guiding significance of gas drainage and treatment.