Flammability and Explosion Risk of Post-explosion CH₄/air and CH₄/coal dust/air Mixtures

ABSTRACT

The post-explosion gaseous environment in a coal mine influences the occurrence of secondary explosions. The flammable and explosion risk of post-explosion gases (CH₄/air and CH₄/coal dust/air mixtures) was evaluated. Explosion tests were carried out in a 20-L spherical explosion device under conditions with different air-fuel ratios. The composition and volume fraction of post-explosion gases were collected and analyzed. CO and H₂ are two main possible flammable gas products with increasing initial fuel-air ratio. Unexpectedly, H₂ was generated after a CH₄/air explosion when the initial φ(CH₄) ≥ 13%, in which condition the concentration of O₂ was far from sufficient to oxidize CH₄. The volume fraction of flammable gas in residual gases of CH₄/coal dust/air mixture explosions was higher than that of CH₄/air mixtures. It was found that the secondary explosion risk increased significantly when coal dust was involved in a methane explosion. The lower explosion limit (LEL) of post-explosion flammable gases decreased with the increasing mass concentration of coal dust. The flammable component of such post-explosion gases affected the secondary explosion.

KEYWORDS:

• Coal
• explosion residue
• 20-L sphere
• secondary explosion

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (51174200) and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD);Priority Academic Program Development of Jiangsu Higher Education Institutions [PAPD];