Explosion characteristics of H2/CH4/air and CH4/coal dust/air mixtures

Abstract

Using a standard 20 L explosion spherical vessel, the explosion characteristics of H 2 /CH 4 /air and CH 4 /coal dust/air mixtures as well as the solid explosion products were investigated. Results show that the presence of molecular hydrogen yield from coal spontaneous heated process would significantly increase the maximum explosion pressure and pressure rise rate of H 2 /CH 4 /air mixtures. With the increasing of hydrogen contents in the mixtures, the lower explosion limits decrease correspondingly. In the cases with appropriate hydrogen and methane ratio, the lower explosion limits of the mixture are even smaller than that of each gas components'. The rules of CH 4 /air/coal dust hybrid mixtures explosion parameters present a increasing and then decreasing trend with the methane contents in the hybrid mixtures, and the peak values appear at the point that the methane volume fractions is 0.1. Furthermore, dust explosion processes and some influencing factors, such as dust concentration and initial pressure and so on, are also analyzed and discussed systematically. Supported with the scanning electron microscope (SEM) and image processing technology, the surface fractal characteristics of solid explosion products are analyzed and compared for each coal dusts. Research results may have great significance for the hybrid mixtures explosion kinetic reveal, risk assessment and preventions in the coal mine. In this paper, a standard 20 L explosion spherical vessel was used to investigate on the explosion characteristics of H 2 /CH 4 /air and CH 4 /coal dust/air mixtures. The effects of H 2 on CH 4 /air explosion property and also the effects of CH 4 on the Coal dust/air explosion property as well as the solid explosion products were analyzed systemically. ► CH 4 /H 2 /air explosions are greatly strengthened by the presence of H 2 . ► CH 4 /H 2 /air explosion limit is lower than that of CH 4 /air and H 2 /air. ► CH 4 /air/coal dust explosion character would be changed by the presence of CH 4 gas. ► Coal dust explosion products show great difference in particle’s physical features.