Study On Chemical Mechanism Of Gas-coal Dust Explosion And Coupling Of Explosion Power And Ventilation Power

Due to the complex conditions of coal mines,safety hazards are more hidden,resulting in frequent coal mine accidents.Among the coal mine safety accidents,gas-induced deposition coal dust explosion accidents are very powerful and cause significant casualties,and the underground coal mine r equires real-time ventilation,and the toxic and harmful gases generated by the explosion will keep spreading with the wind flow,leading to the expansion of the scope of the disaster and seriously affecting the underground rescue.Based on the above statu s quo,this paper adopts molecular dynamics,physical experiments,numerical simulations and other research methods to systematically study the mechanism of gas and coal dust and the effect of wind speed on the propagation characteristics of gas-induced deposition coal dust mixture explosion,and proposes a prediction method for the explosion propagation law.The molecular structures of the coal samples of HM,YM&WYM were constructed from the experimental results of industrial analysis,elemental analysis,solid-state nuclear magnetic(¹³C-NMR)and X-ray photoelectron spectroscopy.The combustion of coal dust at the beginning of the explosion was calculated by the AMS software,and the product change pattern at the beginning of combustion was found,and th e coal molecules release CO,H2,CH4,C2H2,C2H4 and other products in the combustion.The number of molecules of CO,C2H2 and C2H4 gradually decreases as the oxygen concentration increases and the volatile fraction decreases,and the number of molecules precipitated by C2H4 even decreases to 0.It was found that when the oxygen concentration is low,coal dust and CH4 are in competition during combustion,and coal dust and CH4 will react together when there is sufficient oxygen.An experimental study of gas-coal dust explosions in the absence of wind was carried out.It was found that as the concentration of coal dust increased,the pe ak pressure,maximum flame velocity and maximum temperature in the pipe tended to increase and then decrease,while the coal samples would gradually decrease in peak pressure,maximum flame velocity and maximum temperature as the degree of deterioration increased.Experimental study of the explosion characteristics of gas and coal dust explosion in the ventilation pipe network,found that the gas and coal dust explosion study found that the concentration of less than 100g/m3 of coal dust involved in the exp losion,the maximum explosion pressure,flame propagation speed and flame temperature in the pipe with the increase in wind speed and become larger;when the coal dust concentration is greater than 100g/m³,the explosion produced the maximum explosion pres sure,flame propagation speed and flame temperature with wind speed increases and decreases.In the wind speed of 3m/s,4m/s,the flame propagation speed at the end of the pipe is even 0m/s.Simulation study of the coal dust factor and the effect of wind s peed on the peak value of CO generated by the explosion,it was found that the maximum concentration of CO gradually decreases as the degree of coal deterioration increases.When the mass concentration of coal dust is increasing,the peak concentration of CO generated by the explosion also gradually increases.In the ventilation state due to the effect of wind speed,it will lead to the same concentration of coal dust as the wind speed increases the CO concentration generated becomes larger;when the wind s peed in the pipe is too large,the CO concentration at the end of the pipe tends to 0%.The explosion characteristics of gas-coal dust in longwall working faces were investigated.It was found that when the ignition source was exposed to the wind flow,the wind speed during the initial explosion period made the explosion chemical reaction rate at the ignition lower,making the chemical reaction occur more slowly and the pressure,flame velocity and CO rise slowly,but as the explosion developed,the turbulence caused by the wind flow and the explosion shock wave strengthened,resulting in a rapid increase in pressure,flame velocity and CO concentration.As the wind speed increases,the pressure,flame speed and CO concentration also rise gradually.Considering the non-linear and timely nature of gas and coal dust explosion,RNN neural network was selected as the explosion propagation prediction model.The input and output parameters of the neural network were determined by analysing the influencing factors of gas and coal dust explosion,and the 2-layer hidden layer was found to be the optimal model after training.Using sensitivity analysis,the influence of the input parameters on the output parameters was investigated and it was found that the main factor controlling the explosion of gas and coal dust was still the nature of the fuel itself.The prediction of explosion pressure and CO concentration in the 160m tunnel was obtained,and the prediction error was within 5%,and the model prediction was good.The above research results can provide theoretical basis and technical support for the prevention and control of coal-dust mixed explosion disasters induced by gas in underground coal mines and disaster relief.The dissertation has 86 figures,22 tables,and 205 references.