A Research On Mechanism Of Enhancing The Desorption\diffusion\ Flowing Of Coalbed Gas By Ultrasonic Vibrating

This paper is based on the financial aid system of ministry of education science and technology's key project at"A research on mechanism of enhancing the desorption,diffusion,flowing of coalbed gas by ultrasonic vibrating", through developing experimental study the characteristics of methane's adsorption,desorption,seepage under sound field;research on mechanism of enhancing the desorption,diffusion,flowing of coalbed gas by ultrasonic vibrating,numerical simulation of coaled gas seepage under sound field,get such main achievenents are listed as following:The curve of adsorption isotherm of coal to methane's rule are similarly at the condition of adding sound field and no sound field ,the adsorpiton of coal to coalbed gas be decreased under sound field,and as the ultrasonic intensity increased the adsorption decreased.The characteistics of adsorption can be desicribled by D-R equation,Langmuir equation,Freundlich equation,BET equation,and D-R equation,Langmuir equation can desicrible it well.The adesorption parameters of a,K',Q_m,Q_n were decreased under sound field,and decreased follow the ultarsonic intensity incresaed.Under the condition of adding sound field and no sound field, the gas kinetics curve of desorption are similarly, sound field are benifit for the desorptiong,diffusion of gas in coal,theadsorption law be desicribled by empirical formula,percolation model and diffusion model,and the diffusion model can desicirble the desorption characteistics of gas in coal better.Under sound field,the parametersα,Q_d∞of desorption model increased,β,B,b₀ decreased.The experimental study of gas in coal's desorption characteistics under the condition of different temperatures shows that,as the temperature increased,the kinetic energy of coaled gas incresed, the ability of coal to coaled gas descreased,it benifit for coaled gas desorpted from coal.The desorption model's parameters ofα,Q d∞increased follow the temperature increased,the parameter of B and b₀ descreased with temperature inceased.The diffusion characteistics of coaled gas in coal under the condition of add sound field and no sound field can be discribled by single diffusion model, the sound field effect made the criterion of mass transmission increased,it shows that the diffusion resistance in coal is decreased through sound field,as the diffusion ability increased,the gas's diffusion concentation in coal are more uniform,then the internal and external diffusion concentation become smaller.Under sound field,the diffusion coefficients increased, the criterion of mass transmission F'₀ increased,the gas's diffusion rate in coal become big,mass transfer velocity become quick,the sweep range of concentration distrubance become wide.The mechanism of ultrasonic promote the desorption,diffusion,seepage come from the ultrasonic's mechanical vibration and thermal effecting. The results of experimental and numerical analysis shows that,the permeability of coal is closely related with the effection of the state of stress,pro-pressure,temperature,sound field.Sound field can protome the permeability of coal sample,and in coaled gas drilling,coaled gas's seeage is closely related with ultrasonic's acoustic frequency,power.