Study on the Effect of N2/CO2 Mixed Gas on the Explosion Characteristics of Methane-Ethane-Air
J.-G. Wang1,2, J.-H. Zhang1, J.-J. Chen3, J.-Y. Li1, S. Zhang1
1College of Environment and Safety Engineering, Fuzhou University, Fuzhou, China
2Fuzhou University Zhicheng College, Fuzhou, China
3Aero-Engine Superior Materials (Zhenjiang) High-Temperature Alloys Co., Ltd, Zhenjiang, China
Keywords: methane, ethane, N/CO, explosion suppression, reaction kinetics
Abstract
The main components of natural gas are methane and ethane. Despite their widespread use, gas mixtures are explosive. This paper studies the explosion characteristics of a premixed methane-ethane-air mixture (fuel equivalence ratio ϕ = 0.7 ÷ 1.3) in a 1 m3 spherical chamber, as well as the explosion suppression effect upon adding an inert N2/CO2 mixture. The inhibition mechanism is analyzed from the standpoint of chemical kinetics. The results show that the maximum explosion intensity, characterized by peak pressure and maximum rate of pressure rise, is observed with a slightly enriched mixture (ϕ = 1.1). The deformed flame front propagation velocity is 2.60 m/s, the maximum explosion pressure is 830.58 kPa, and the maximum rate of pressure rise is 10.31 MPa/s. The ten key elementary reactions that most significantly affect the concentration of reactive radicals (H•, O•, OH•) and the explosion temperature coincide; their sensitivity coefficients change in the same direction. At the same volume fraction of inert gas, increasing the CO2 content in the N2/CO2 mixture enhances explosion suppression. This is explained not only by the higher heat capacity of CO2 but also by its direct participation in elementary reactions, leading to the termination of branching chains and the formation of stable products. Complete explosion suppression is achieved with the introduction of 25% (volume) of the inert mixture.
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