Inhibition of the Premixed CH4/Air Deflagration by Powdered Extinguishing Agents

In order to improve the utilization rate of extracted coal-bed methane, effective safety measures for low concentration gas transmission line must be provided. In this work, suppression of gas explosion in a channel by powdered extinguishing agents (i.e. ferrocene and aluminium hydroxide) was investigated. The methane concentration in the explosive mixture was 9.5% by volume. The experimental channel is 150mm×150mm×500 mm in dimensions, in which three pairs of obstacles spaced 100 mm apart was configured to enhance the flame propagation speed. The high speed camera was used to capture flame images, by which the arrival time and the propagation speed of flame would be calculated. The performance of powdered extinguishing agents on gas deflagration suppression was evaluated. The results showed that the suppression effectiveness of the powdered ferrocene is closely related with the solid concentration. For the solid concentration of 80 g/m3, the arrival time of flame to the channel exit was increased by 32.5%, and the peak flame propagation speed was declined by 15.6%. In contrast to aluminium hydroxide, ferrocene showed the better explosion suppression characteristic. The results showed the practical foundation to gas explosion suppression by ferrocene in coal mines.