Experimental and kinetic investigation on propylene explosion risks under high temperature and pressure conditions

In the acrylic acid production process from propane, propylene may be present under high temperature and pressure conditions in the reactor, posing a potential explosion risk. However, there is limited research on the explosion characteristics of propylene under these conditions. The flammability limit and limiting oxygen concentration (LOC) of propylene were systematically investigated under varying initial temperatures (303–393 K) and pressures (0.1–2.0 MPa) in this study. The results demonstrate that the flammability range of propylene expands rapidly with increasing temperature and pressure, thereby elevating the explosion risk. The UFL shows a stronger sensitivity to thermodynamic conditions compared with the LFL and LOC, exhibiting a linear relationship with temperature and an exponential relationship with pressure. Le Chatelier's formula provides accurate predictions for the LFL and acceptable agreement for the UFL in propane/propylene mixtures. An explosion island diagram was established to visualize the flammability boundaries across different initial conditions, offering a practical tool for explosion risk prediction. Chemical kinetic analysis further reveals that the chain-branching reaction R1:H + O₂ = O + OH plays a dominant role in accelerating temperature rise near the flammability limit. This study provides both experimental evidence and kinetic insights into the explosion characteristics of propylene, which can support improved safety design and risk assessment in industrial applications.