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

Abstract

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.

Numerical Study on Premixed Methane–Air Flame Propagation in a Confined Vessel at Low Initial Temperature

“…With the increasing emphasis on environmental protection and demand for energy and the increasing shortage of traditional energy such as oil, the development and utilization of LNG and oxygen-bearing coal-bed methane show significant economic and social benefits. − However, in the LNG storage and oxygen-bearing coal-bed methane liquefied production, the methane concentration in the gas phase may be within the flammability limits, causing a potential explosion hazard and resulting in significant economic losses and casualties. − Regardless of the combustion caused by LNG leakage or low-temperature liquefaction of oxygen-bearing coal-bed methane, there is a common ground: the initial temperature of the combustion is cryogen (typically lower than 150 K). Under low-temperature conditions, the combustion characteristics and mechanism are bound to be very different from those at room temperature, and there is a lack of research on gas combustion at low initial temperature.…”

Influence of Cavity Width and Powder Filling in a Cavity on Overpressure Evolution Laws and Flame Propagation Characteristics of Methane/Air Explosion

“…The electrode is placed on the flange at the beginning of the pipe network system, and an ignition energy of 10 J is selected as the starting energy for the experiments. 33 The explosion suppression device is a self-designed rectangular cavity, and its physical picture is shown in Figure 2 . The dimensions of the cavity (length × width × height) mentioned in the experiments include 500 mm × 300 mm × 200 mm, 500 mm × 500 mm × 200 mm, and 500 mm × 800 mm × 200 mm.…”

Flammability and Explosion Characteristics of Methane in Oxygen-Reduced Air and Its Application in Air Injection IOR Process

“…The vessel is placed in a constant temperature drying oven. A tungsten wire coil with a diameter of 1.2 mm powered by a 24 V and 400 W direct current source is used to ignite the gas, which can exceed the minimum ignition energy of methane under high temperatures and high pressures. − The Ignition tungsten is placed at one end of the container and connected to the external through sealed stainless steel electrodes. The experimental results obtained for methane at atmospheric conditions can be compared with the literature data that were obtained using different ignition criteria, shape and size of the explosion vessels, and the ignition type, as shown in Table .…”