A Comparison Study of Hybrid Flame of Methane/Coal Dust Mixture in Vented Explosions

The interaction of the induced flame front with coal dust cloud with different equivalence ratio was experimentally investigated by the vented flow with Kv=5.4 and Kv=10.9, and compared to the vented flow pressure characteristics of methane with and without coal dust. The increasing second peak structure of hybrid mixture pressure suggested that a dust secondary explosion does exist in external space of vent vessel. The pressure results with the increasing equivalence ratio of hybrid mixture also exhibit that there is not rich limit for coal dust in hybrid explosions. However, the maximum pressure increase ratio reveal the maximum pressure increase ratio will decrease with the increasing equivalence ratio of hybrid mixture if it is over one, that shows the dispersion of coal dust cloud take clearly effect on the heating spreading between coal dust particles. The initial methane concentration also takes significantly impact on the combustion of coal dust due to changing the induced flame front strength.