Numerical simulation and environmental impact assessment of oil vapor diffusion in surrounding residential areas before/after vapor recovery at petrol stations

Abstract

ABSTRACT Oil vapor emitted during refueling process has caused serious issues of air pollution, especially the environmental impact in surrounding residential areas. Most petrol stations have installed oil vapor recovery systems, but some stations did not properly maintain or switch on them. With the increasing emphasis on ecological environmental protection, it is more crucial to investigate the internal mechanism of vapor-air mass transfer. In this study, a computational fluid dynamic (CFD) model was developed and verified to analyze the effects of wind speed, vehicles number, and residential layout on oil vapor diffusion in residential areas. Simultaneously, the effectiveness of oil vapor recovery was assessed by comparing contamination before and after recovery. Results indicate that wind speed greatly affects the area and location of excess emission areas (EEAs). As the wind speed increases from 2 m/s to 4 m/s, highest concentration, distance to buildings and width of EEAs decreases by 49.1%, 43.8%, and 33.3%, respectively, and EEAs disappear at the wind speed of 6 m/s. Vehicles number has a more significant effect on the symmetry of EEAs, and EEAs become gradually symmetrical as the number increases from 3 to 12. Further, the enclosure layout proves to be an effective layout for protecting residential air, with a minimum concentration of 0.18 mg/m3. Notably, the effectiveness of oil vapor recovery is remarkable, with a purification rate of 98.5%. These findings can offer a valuable guidance for controlling air pollution in residential areas and enhancing the environmental protection level of petroleum enterprises.