Influence of initial gas concentration on methane–air mixtures explosion characteristics and implications for safety management

Abstract

Gas explosions, particularly those involving methane–air mixtures, present considerable hazards in confined spaces, such as coal mines. Comprehending the explosion characteristics and their correlations with initial gas concentrations is vital for devising effective safety measures. This study examines the influence of initial gas concentration on explosion temperature, overpressure, and flame evolution in methane–air premixed gas explosions, utilizing a custom-built 20-L spherical explosion experimental apparatus. The explosion temperatures display an oscillatory pattern, reaching maximum values at 6.5%, 9.5%, and 12% initial gas concentrations, with corresponding temperatures of 995 K, 932 K, and 1153 K. The maximum overpressure exhibits an initial rise and fall trend, modeled by an exponential function. Notably, in proximity to the 9.5% concentration, the pressure wave fosters the reverse propagation of the flame wave, leading to a secondary temperature increase. Flame sensors were employed to investigate the presence, absence, and duration of flames, demonstrating that elevated initial gas concentrations resulted in more prolonged flame durations and increased harm. At an initial gas concentration of 9.5%, a persistent flame is generated instantaneously during the explosion. Furthermore, the study analyzes the interplay between temperature and overpressure, underscoring the significance of mitigating high-temperature burns near tunnel walls and enclosed spaces. These findings advance the understanding of gas explosion dynamics and hold substantial implications for safety measures in coal mines.

Experimental study on characteristics of flame propagation and pressure development evolution during methane-air explosion in different pipeline structures

“…In the study on the propagation law of gas explosion, factors such as gas volume dose, pipeline cross-sectional area, and obstacle distribution greatly influence on the overpressure evolution laws and flame propagation characteristics of shock wave (Huang et al, 2020;Niu et al, 2021;Yan et al, 2022;Jia et al, 2023;Niu et al, 2020) established a set of experimental system in pipeline network to test the propagation characteristics of shock waves in complex areas and found that there is a pressure increasing area in the corner branch of the shock wave, but it is not affected by the flame. Zhu et al (2021) investigated the overpressure evolution law and the flame propagation process when a gas explosion occurs in U-shaped longwall coalface and H-shaped crosscut by numerical simulation, and found that a very high reflected pressure exists close to the corner but decays very fast in the free spaces.…”

Experimental study on gas and coal dust explosive overpressure and flame dynamic characteristics in an engineering-level test roadway

“…When the gas concentration (or the concentration of coal dust suspended in the air) and oxygen concentration reach a certain limit and a high-temperature heat source is encountered, gas or coal dust explosion occurs, which not only destroys the underground ventilation network and endangers the safety of life and property but also causes a secondary explosion and brings devastating disasters to the mine. (Wang D M et al, 2021;Jia et al, 2023;Li et al, 2023). Gas and coal dust explosion includes complex physical and chemical reaction processes, and the propagation process of shock wave is a complex dynamic process of gas-solid two-phase flow coupling development.…”

“…In the study on the propagation law of gas and coal dust explosion, factors such as gas volume dose, coal dust concentration, pipeline cross-sectional area, and obstacle distribution greatly influence on the overpressure evolution laws and flame propagation characteristics of shock wave (Wang et al, 2018;Niu et al, 2019;Niu et al, 2021;Jia et al, 2023). Ma et al (2020) studied the influence of coal dust on methane-air explosion characteristics at low temperature.…”