Research On The Propertries Of Coal Dust Explosion And Technology Of Dust Fall And Explosion Suppression

As one of the top five natural disasters,coal dust endanger the health of workers and remain the risk of explode.With the advancement of mechanization and automation of coal mining,the output of dust has been increased.It is extremely urgent to study the theory of coal dust explosion and improve the control and prevention equipment.The related research background and meaning of this paper was introduced and the ignition mechanism,explosion propagation laws and control technologies at home and abroad were analyzed and summarized.The theory of origin,evolution of blast and spread of shock wave was briefed from the two aspects of thermal explosion theory and free radical theory and then the influence factors on the damage of dust bla sting were introduced.Afterwards,the attenuation reasons of shock wave in different tunnels were explained briefly.All the contents above lay a theoretical foundation for the numerical simulation following.In order to study the propagation law of shock wave of coal dust-gas explosion under different initial conditions,the straight tunnel models were built and the variation trends of shock wave overpressure under different gas content,coal dust concentration and particle size was simulated by Fluent.The result shows that the overpressure value and its rising rate of explosion shock wave show the trend of increasing first and then decreasing with the increase of gas content.The overpressure values show the same phenomenon with the increase of coal dust concentration.The overpressure of explosion shock wave,flame temperature and its velocity were effected significantly by the change of coal dust particle size: the smaller the particle size is,the higher the flame velocity and temperature are.In order to study the propagation law of shock wave of coal dust-gas explosion under different complex tunnels,the turning roadway,bifurcation and variable cross-section roadway with different angles were built and the overpressure changes in each case on the observation point set at typical locations was simulated by Fluent.The result shows that the greater the bend angle of the roadway was,the smaller the pressure in the straight roadway after turning,the increase of the turning angle is beneficial to the pressure attenuation of the shock wave.When the bifurcation angle of increased,the overpressure value of the downstream straight roadway increased,while the pressure value of the bifurcated roadway would decrease gradually.When the shock wave moved from the narrow roadway to the wide roadway in the saltation cross-section tunnel,the overpressure reduced significantly and this attenuation is more obvious while the latter section was wider.An automatic dust reduction explosion suppression device was designed based on the analysis about mechanism of coal dust adsorption and settlement by spray.In this system the multi-sensor program was combined with other security systems,for the purpose of information sharing and effective identification to the hazard.Two corresponding operations aimed to alarm and danger was designed respectively,and an extra rapid spray loop driven by mechanical force was highlighted.The designs above have the advantages of low cost and easy installation,and increase the system reliability.