Investigation on the flammability limit and limiting oxygen concentration of propane/propylene mixture at elevated temperature and pressure

With the development of industrial technology, a new process has emerged for the production of acrylic acid using propane as a feedstock. There are few studies on the combustion characteristics of propane/propylene mixtures at elevated temperature and pressure. In this study, a flammability limit test system was used to determine the flammability limit and limiting oxygen concentration of propane and propane/propylene mixture at different initial temperatures (30–120 °C) and pressures (0.1–2 MPa). The results showed that with the increase of initial temperature and pressure, the flammability limit range expanded, and the limiting oxygen concentration reduced. In addition, the flammability limit range of the propane/propylene mixture is greater than that of propane, indicating that the addition of propylene increases the explosion risk. The empirical formula of the experimental gas was fitted to predict the combustion and explosion parameters under different conditions. In addition, the chemical reaction simulation of propane/propylene mixture was also investigated. The results showed that with the propylene ratio increased, the adiabatic flame temperature and adiabatic overpressure increased, the proportion of H-abstraction reaction decreased and the proportion of pyrolysis reaction increased significantly, which promoted the explosive reaction and the increase of explosion temperature.