Abstract: This study uses Aspen Plus software to draw the vapor-liquid equilibrium phase diagram of the propan-butane binary system based on the physicochemical properties of propane and butane. Through analysis, it was found that after LPG leakage, propane in the liquid phase will immediately vaporize, while butane will form a liquid pool and then evaporate and vaporize. Based on these findings, two distinct leakage models for propane and butane were developed respectively. Subsequently, after calculating key parameters such as intermolecular forces, diffusion coefficients, and explosion limits of mixed gases, a two-phase LPG leakage model was established through multi-source gas leakage numerical simulation method. Through the simulation of a LPG tanker leak accident, it was found that propane and butane exhibit completely different gas concentration distributions during the diffusion process, which affects the entire hazardous area. Therefore, the influence of component factors cannot be ignored when simulating LPG leak accidents. Comparative analysis with the Burro 8 experimental dataset demonstrates favorable agreement, validating the model's capability to accurately replicate real-world LPG leakage scenarios.

Key words: LPG storage tank, vapor-liquid equilibrium phase diagram, explosion limit, Gaussian dispersion model