Experimental study on coal gas adsorption characteristics under action of low temperature liquid nitrogen

Liquid nitrogen cracking coal seam permeability technology has good prospects,but research on the gas adsorption characteristics of coal body under th e action of low temperature liquid nitrogen is still not perfect,and most of the research is in the preliminary research stage. In order to study coal gas adsorption charact eristics under the action of liquid nitrogen freezing-thawing and the initial temperature,the change law and trend of coal gas absorption characteristics under the action of the coal are studied. A coal sample from Xinjiang Sulgougou Coal Mine was selected to study the adsorption characteristics under different liquid nitrogen freeze-tha W time( 0,30,60,90, 120 min)and the different initial temperature( 30,40,50,60,70 °C) using PCTPro high pressure adsorption apparatus. Through the study,the change of adsorption capacity,adsorption of increment and the saturated adsorption amount under the condition of different liquid nitrogen freezethaw time and initial temperature were obtained,three kinds of adsorption theory models were selected to fit the experimental results. The variation of coal adsorption characteristics under the influence of two variables were concluded. The results show that the coal gas adsorption capacity gradually increases with the increase of freeze-thaw time and decreases with t he increase of initial temperature. The saturated adsorption capacity increases with the increase of liquid nitrogen freeze-thaw time. The initial temperature increase of t he test showed a downward trend. Fitting different theoretical models under two-variable conditions,the results show that the Langmuir theoretical model has the best fit ting effect,the highest degree of fit,and a small error range.Under the condition of two variables,there is no obvious rule for adsorption constant b value,while the adsorp tion constant a increases with the increase of liquid nitrogen freezing-thawing time and decreases with the increase of initial temperature.