Experimental Study of Minimum Ignition Energy of Methane-Air Mixtures at Low Temperatures and Elevated Pressures

Previous research results show that, at the top of the distillation column of the liquefied process of oxygen-bearing coal-bed methane (CBM), an explosion hazard may happen. The minimum ignition energy (MIE) of combustible gas reflects the sensitivity of the explosion. Although MIE has been experimentally and theoretically studied at normal or elevated temperatures, there are no relevant data aimed at the environment (low temperature and high pressure) which exists at the top of the distillation column. Therefore, in this study, the MIE of a methane-air mixture was tested using a low temperature experimental vessel in the low temperature (123-273 K) and pressure (0.1-0.9 MPa) ranges. Our research results show that MIE increases with the decrease in initial pressure P-0 or temperature T-0. When the initial pressure is relatively low, both the initial pressure and temperature significantly affect the MIE. However, at higher initial pressure, the initial temperature and pressure have relatively smaller impact on MIE. The MIE linearly correlates to 1/P-0(2), whereas it linearly correlates to 1/T-0. With the decrease in initial temperature, the degree of the impact of initial pressure on MIE gets larger. Additionally, with the increase in initial pressure, the degree of the impact of initial temperature on MIE gets smaller. The changing rule of our experimental MIE with initial temperature and pressure shows good accordance with published results. The energy generated by the human body, collision between the metals, lightning, and external fire is higher than the MIE of methane at the top of the distillation column, which indicates that an explosion hazard may happen. Thus, corresponding safety measures should be taken.