Experimental Study Of Methane-Coal Dust Compound Explosion In Closed Vessel

Coal is important basic energy and industrial raw material, with the continuous exploitation of coal resources, methane and coal dust explosions have occurred, resulting in significant casualties and property losses. Therefore, the study of methane and coal dust flame propagation and blast wave propagation can reduce potential loss of explosion. This paper studied methane-coal compound explosion by using photosensitive flame sensor and high-frequency pressure sensors in closed vessel.The main work and conclusions are as follows:(1) Experimental apparatus used for gas, dust and gas-dust explosion are designed and set up.(2) The characteristics of premixed methane-air explosion and methane-coal dust compound explosion were comparatively analysed.Results show that the flame velocity significantly increases in methane-coal dust explosion compared with methane-air explosion. Explosion pressure increases when the methane concentration is low and decreases when the methane concentration is 9.5% in methane-coal dust explosion compared with methane-air explosion.(3) The flame propagation of methane-air explosion and methane-coal dust compound explosion is similar. After ignition, the flame velocity along the tube length increases dramatically at first, when the flame reaches to the position of 0.425 m from ignition position, the flame velocity is the biggest, after that, the flame velocity decreases dramatically to lm/s or so.(4) The explosion characteristics of the methane-coal mixture in different initial state parameters (methane concentration in coal ratio, coal particle size and ignition delay time) were studied.Results show that the flame propagation velocity is greater when the methane concentration is closer to stoichiometric concentration; the flame velocity, Pmax and (dP/dt)max increase first and then decrease with the coal concentration,the optimal concentration range is 500g/m3--600g/m3; the flame velocity, Pmax and (dP/dt)max increase when coal particle size decreases; the flame velocity, Pmax and (dP/dt)max increase is greater when the delay time is 500ms. (5)The quantitative relate equation within Vmax, Pmax, (dP/dt)max and initial state parameters (coal particle size and ignition delay time)is attained by taking regression analysis of explosion experiments data.(6) The flame velocity increase significiantly with obstacle. The flame velocity increases unconspicuous when the obstacle position is far away from the ignition point, Pmax changes little with the obstacle position.