Study on the Synergistic Inhibition Mechanism of N2/CO2 on n-Butane Explosion

N-butane is an extremely versatile low-molecular-weight alkane. It serves not only as a clean, efficient energy carrier but also as a key starting material in modern petrochemical industries. Its inherent high flammability and explosive properties pose significant safety challenges during production, storage, transportation, and use. To effectively mitigate explosion risks, a multi-viewport gas/dust/liquid mist explosion suppression integrated test apparatus was employed to investigate the explosion process of n-butane-air mixtures and the suppression effects of pure N₂ and N₂/CO₂ mixtures on this process. By varying n-butane concentrations, the optimal explosive concentration was determined. Subsequently, different concentrations of nitrogen and varying mixtures of nitrogen/carbon dioxide were introduced. As the proportion of carbon dioxide increased, the maximum explosion pressure, maximum pressure rise rate, and explosion index of the n-butane-air mixture all decreased progressively. The time to reach peak pressure and the time to reach maximum pressure rise rate were progressively delayed. Adjusting the inert gas ratio revealed that the physicochemical synergistic suppression effect of N₂/CO₂ outperformed the physical suppression effect of N₂ alone. High-speed camera analysis of changes in flame velocity and structure further validated the superiority of this synergistic suppression effect. It was concluded that the physicochemical synergistic suppression effect of N₂/CO₂ outperforms the physical suppression effect of pure N₂. Furthermore, the chemical reaction kinetics of n-butane-air premixed gas under varying conditions was investigated via Chemkin numerical simulation software. The results demonstrate that as the proportion of CO₂ in the inert gas mixture increases, the sensitivity of explosion pressure gradually diminishes, and the explosion reaction rate decreases substantially. In comparison to pure N₂, CO₂ exhibits a stronger synergistic physicochemical inhibitory effect on H radicals and OH radicals during the reaction process. Moreover, it modulates the maximum reaction rate (ROP) of elementary reactions, thereby effectively suppressing the explosion reaction of n-butane premixed gas. This provides experimental evidence and theoretical support for inhibiting n-butane explosion technology.