Study And Application Of Multi-factors Affecting Gas Desorption Law Of Coal Sprayed With Compound Surfactants

With the progress of technology,coal mining technology has been greatly improved,and gas accidents have decreased significantly.However,in coal mining,gas overrun still occurs.Spraying surfactant to specific high concentration gas area can effectively reduce local gas concentration in coal mining face.In order to obtain the law of gas desorption of coal body affected by multi-factor spraying compound surfactant solution,this paper optimized the surfactant compound scheme according to the influence on the wettability of coal body by combining theoretical analysis,laboratory experiment and field experiment.Combined with the influencing factors of gas concentration in coal mine,the effect law and effect of different equilibrium pressure,atomization pressure and coal particle size on inhibiting gas desorption of compound surfactant spraying under ventilation conditions were analyzed.Based on the final optimization scheme,the field industrial test was carried out in coal mine working face.It provides a scientific basis for the formulation of gas desorption inhibition scheme using compound surfactant solution in coal mine.The main conclusions are as follows:(1)The mixture of 0.40%nonionic surfactant APG and JFC has the greatest influence on the wettability of coal,the surface tension is 28.10 mN·m-1 and the settling time of pulverized coal is 12.31 s.(2)After the compound surfactant was sprayed on the gas-containing coal,the variation law of the average gas concentration at each measuring point in the experimental box was P2>P1>P3>P4>P5.The peak gas concentration is positively correlated with the equilibrium pressure,but the increase amplitude decreases with the increase of equilibrium pressure.Compared with aqueous solution spraying,the peak value of gas concentration at each measuring point decreased with the increase of equilibrium pressure.The maximum decrease was when the equilibrium pressure was 0.10～0.13 MPa,and the effect of compound surfactant on inhibiting gas desorption was stronger than that of aqueous solution.(3)The peak value of gas concentration is negatively correlated with atomization pressure after spraying compound surfactants in gas-bearing coal.With the increase of atomization pressure,the inhibition efficiency of surfactants increases gradually.When the atomization pressure reaches 2.0 MPa,the inhibition efficiency of surfactants reaches the maximum.(4)The peak value of gas concentration was negatively correlated with the particle size of coal after spraying compound surfactants.The larger the particle size,the lower the gas concentration,but the attenuation rate decreased rapidly-slowly-rapidly with the increase of particle size.Compared with aqueous solution spraying,under the condition of compound surfactant spraying,the peak value of gas concentration at each measuring point decreases to varying degrees with the increase of coal particle size,and the maximum decrease is that the coal particle size is between 20.00 mm and 30.00 mm.(5)Through the field industrial test,the average gas concentration in the working face shows a downward trend compared with that in the non-spray tunneling,and after pure water spraying and compound surfactant spraying.After spraying pure water,the peak value of gas concentration in the working face decreased by 0.14%,and the average concentration decreased by 0.11%.Compared with spraying pure water,the peak value of gas concentration in the working face decreases by 0.03%,and the average concentration decreases by 0.029%.The efficiency of inhibiting gas desorption by surfactant increases by 22.31%.In this paper,based on the optimized compound surfactant,through the independent research and development of multi-factor surfactant spraying device in the laboratory,the law of multi-factor influence on the gas desorption of compound surfactant solution spraying coal is studied.Combined with the change trend of average gas concentration in the working face after compound surfactant spraying in the field industrial test,the influence law of compound surfactant spraying on coal wetting and desorption under the influence of multi-factor is obtained.The research conclusion can provide useful reference for the engineering application of surfactant solution to control gas overrun.