Study on the Characteristics and Influence Factor of Methane and Coal Dust Gas/Solid Two-Phase Mixture Explosions

This research aimed to the characteristics and influence factor of methane and coal dust gas/solid two-phase mixture explosions by experiment. Through comparative analysis of flame propagation characteristics, pressure, flame temperature and products, the characteristics of gas/solid explosions and its influence factor were analyzed. And the influence mechanism was also revealed. Results indicate that the coal dust parameter and methane concentration were the important influence factor on mixture explosions. Explosion intensity could be indirectly affected by influencing the flame propagation. Under the determined coal dust parameter, the explosion parameter showed a change trend of increase firstly and then decrease as the methane concentration increased. And it was the greatest at 6% methane concentration. However, the concentration of coal dust corresponding to the maximum pressure was variable and was decreased successively as the methane concentration increased. The corresponding dust concentrations were 500 g/m3 and 200 g/m3 under 2% and 10% methane concentrations, respectively. Meanwhile, the pressure all presented an increasing trend with the reduction of coal dust diameter under five coal dust concentrations, and the explosion intensity was the greatest at 300 g/m3 coal dust concentration. For 2% methane concentration, the explosion would not occur as the dust concentration was less than 400 g/m3. And the same phenomena also appeared as the methane concentration exceeded 10%. The explosion parameter presented the same change trend with the changes of methane concentration and coal dust parameters. Besides, the thermal stability and decomposition oxidation characteristics of burned coal dust were evidently changed compared with unburned coal dust. The weight loss rate and oxidation reaction rate were decreased, and the corresponding temperature was increased. It indicates that coal dust participated in gas/dust two-phase explosion reactions, and the pyrolysis reaction of volatile matter led to an obvious reduction in the weight loss and oxidation reaction rate. And the precipitation of volatile matter also resulted in an obvious pore structure on its surface. The physical parameters and internal components of coal dust were important factors affecting the reaction rates of gas/dust mixture explosions.