Application of flame arrester in mitigation of explosion and flame deflagration of ventilation air methane

Fugitive methane emissions from underground coal mines are considered a potent greenhouse gas source with a large global warming potential. Application of ventilation air methane thermal oxidiser technology reduces this risk to a large extent. However, it imposes the risk of accidental fires and explosions in the mine site which may claim many lives and cause massive property damage. As such, the necessity of employing safety barriers such as flame arrester seems crucial to protect the mine against the accidental flames and explosion propagation originated from the thermal oxidiser. The aim of this work was to evaluate the effectiveness of an inline flame arrester for the mitigation of methane explosions in a large scale detonation tube. The results corresponding to this study indicated that the flame arrester was capable to effectively mitigate the explosion flames of 5%, 7.5% and 9.5% methane air mixtures (for a 10 m fuel filled section). The flame arrester reduced the pressure wave velocity by 88% and 40% for the explosions of methane-air mixtures of 7.5% and 9.5% methane, respectively. The flame propagation velocities for the 7.5% and 9.5% methane concentrations reduced approximately 32% and 44%, respectively. A significant pressure build-up was observed upstream of the flame arrester when compared with a duct without flame arrester. In addition, the build-up pressure was relatively higher for larger methane concentrations (e.g. 9.5%). These observations highlights that the maximum design pressure of an industrial process plant must be carefully considered when implementing an inline flame arrester due to the possibility of a sudden pressure increase cause by an explosion.