Study On The Law Of Gas Desorption Under The Condition Of Coal Sample Driven By Air Flow

Coal seam gas content is a dual key indicator of mine gas disaster prevention risk assessment and coal bed methane resource reserves.The accuracy measurement of coal seam gas content is a crucial step.The positive pressure countercurrent sampling technology of coal sample sampling method has a high Utilization value,this method is essentially to use the wind and wind pressure to drive the coal sample to the orifice for sampling.There is an essential difference between the environment driven by wind and wind pressure and the environment without wind and wind pressure(static normal pressure).Designed the gas desorption device driven by the wind and wind pressure conditions,and commissioned the manufacturer to manufacture;on the basis of the developed device,the gas desorption simulation experiment under the conditions of downhole positive pressure and countercurrent sampling was carried out.It is suitable for the gas desorption law under this condition,and its desorption law is verified for reliability.It is finally used in engineering practice to correct the gas content measured by the positive pressure and countercurrent sampling method to improve the accuracy of coal bed gas content measurement the following research results are obtained:(1)The experimental device designed and processed can simultaneously measure the gas desorption data of coal samples in the high-pressure airflow driving environment and the subsequent static atmospheric pressure environment,and has the basic function of simulating and studying the gas desorption law under the positive pressure countercurrent sampling environment.(2)Through repeated debugging of the device,the coal sample particle size and air flow pressure value suitable for the normal development of the experiment and the concentration parameter value of the gas concentration detector were selected.(3)Under wind-driven conditions,the gas desorption of the experimental coal sample conforms to the power function type change law;as the wind pressure increases,the gas desorption amount also increases,which plays a role in promoting gas desorption,but with the wind pressure Increasing and increasing the rate of gas desorption presents a tendency to gradually slow down and stabilize.(4)On the basis of the gas desorption law of the experimental coal sample under the wind-driven environment,the corresponding loss calculation formula is proposed,and the reliability of its applicability is verified;finally,the coal The engineering practice application of positive pressure and countercurrent sampling to determine the gas content of coal seam was revised to improve the accuracy of gas content determination.The paper has 66 figures,16 tables,and 69 references.