Research On Flammability Limit And Quenching Mechanism Of Flame Of Premixed Methane Gas

With the sustainable development of the national economy and the society, energy consumption increases day by day. As the coal production and the mining depth are continuously increasing, the problem of the methane discharge and ventilation methane volume in coal mine is becoming serious. In some of our businesses,Mining of coal mine methane used for electricity generation and combustion.Most of the ventilation methane is discharged into the atmosphere for its low concentration, which is difficult for usage. However, there would be existing accidental ignite and temper problems during the discharge process of methane, which causes a series of safety problems for the coalmine production.We collaborate with Australian CSIRO to study the inflaming retarding of combustion in the process of gas discharging in coal mine.The main missions of the paper are included as follows:try to design a gas composition system that is consistent with the reality, and then study the explosion limits and flame extinguished mechanism and conditions of it, which can provide technical supports for designing the industrial fire barrier.Based on the chemical equilibrium method, the explosion limits of the mixed gases are studied by the ChemKin numerical simulation software. Set 1450K as the stagnation temperature to distinguish whether the premixed gas is combustible or not, and forecast the flammable limit. Then design the experiments through the predict results, and test the flammable limit of the mixed gas at specific ratios. The influences of nitrogen and carbon dioxide on the flammable limit of the mixed gas are also studied.The experiments are implemented in a 7L explosive chamber, and the distance between the ignition source and the sensor is 100mm, and whether the mixed gas is combustible is judged by 3 repeated experiments. By testing the flammable limit of mixed gas of methane gas and air, and the flammable limit of different volume ratio of methane gas and carbon dioxide can be obtained.In the Arrester aspects, the main work is study the mechanism and efficiency of flame extinction when the accidentally ignited combustible gas with the fire barrier.The experimental device is a rectangular cross-section tube with a slits equipment of adjustable width. The speed of flame enters into the slits can be adjusted by change the volume ratio of methane in the premixed gas. The flame speed of different entrance and the relationships of different width slits and cross-section shape with the length of the quenching are obtained, which provides a reference base for the design and selection of fire barrier.The flame propagation and quenching phenomenon in the slits are simulated by the Fluent software,1000K is set as the stagnation temperature of the flame extinction, and the quenching length of different flame speed, different slits width and different cross-section shape are discussed.The qualitative simulation technology is applied in the flame quenching research of premixed gas for the first time, and the results are verified by experiments. The verification results show that the simulation technology meets the requirement, so this method can be supplied as a new way to study the flame propagation rule for premixed gas.In the paper, the range of flammable limits of methane and air mixed gas can provide the reference basis for the industrial safety; the relationships of the quenching length in the slits with the flame speed and slits width are obtained, which can guide the design and selection of the fire barrier, so this research has an important application value.