Study on the characteristics and mechanism of inert powder inhibition of gas/coal dust compound explosion
Gas/coal dust composite explosion is a complex process that combines homogeneous and heterogeneous combustion.The com-bustion main control mechanism changes dynamically and the explosion mechanism is more complex,resulting in higher explosion sensit-ivity and explosion intensity compared to single-phase gas or coal dust explosion,which seriously restricts the safe production of coal mines.In order to prevent and control the gas/coal dust composite explosion disaster,two inert powders,sodium bicarbonate and calcium carbonate,are selected to conduct experiments on inert powder suppression of gas/coal dust composite explosions in a 20 L spherical ex-plosion device.Based on the different concentration ratios of gas and coal dust,the inhibition effect of two inert powders on the maximum explosion pressure and the maximum explosion pressure rise rate of the gas/coal dust composite system are analyzed and compared,as well as the differences and connections between the inhibition effect of the two inert powders.And the inhibition efficiency and mechan-ism of the two inert powders on gas/coal dust composite explosions are reflected comprehensively.The research results indicate that sodi-um bicarbonate and calcium carbonate have an inhibitory effect on the explosion of gas/coal dust composite systems with different concen-tration ratios.Sodium bicarbonate can not only suppress the explosion of gas/coal dust composite by physical suppression methods such as decomposing heat absorption,delaying coal dust pyrolysis,and reducing coal dust decomposition rate,but also by chemical suppression methods that consume key free radicals in the explosion reaction,however,calcium carbonate can only suppress explosions through phys-ical heat absorption,so the inhibitory effect of sodium bicarbonate on the explosion of gas/coal dust composite system is better than that of calcium carbonate.Specifically,sodium bicarbonate can completely suppress all working conditions,while calcium carbonate can only completely suppress the gas/coal dust composite working conditions when the gas concentration is below 8%.In addition,the suppression efficiency of two inert powders on the explosion pressure of the gas/coal dust composite system first increases and then decreases with the increase of gas concentration in the system.The suppression efficiency is highest when the gas concentration is 6%and the coal dust con-centration is 100 g/m3;The suppression efficiency of the explosion pressure rise rate of the gas/coal dust composite system gradually in-creases with the increase of gas concentration in the system,and the suppression efficiency is highest for pure gas explosions with a con-centration of 10%.
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