Flame Characteristics in a Coal Dust Explosion Induced by a Methane Explosion in a Horizontal Pipeline

Deposited coal dust, when involved in a methane explosion, aggravates the severity of a mine explosion accident. Mastering the explosion flame duration and flame signal intensity, thereby allowing reasonable determination of the amount of inhibitor to inject and duration, is key to inhibiting propagation of the explosion. To investigate the flame features and propagation of a coal dust explosion induced by a methane explosion, tests were performed in a purpose-built horizontal pipeline system. High-speed recordings of flame, flame signal intensity, and flame duration of the methane explosion and the deposited coal dust involved in that methane explosion were compared and analyzed. The coal dust involved in a methane explosion is characterized by much longer flame duration and a brighter flame, compared with a methane explosion. Under the condition that no new fuel becomes involved in the explosion, the time lag of the flame wave behind the pressure wave rapidly increases with the increase of the length-diameter ratio. The results are of significance for the flame propagation mechanism of deposition dust explosion reaction induced by gas explosion and for the prevention of gas-dust explosion accidents.