Odour dispersion modelling, impact criteria, and setback distances for an oil refinery plant

Abstract

Odour dispersion modelling is considered to be the most effective approach in evaluating odour impact of various air emission sources as field odour measurements are associated with several difficulties. Using odour impact criteria (OIC), odour dispersion modelling could provide a comprehensive map of impact for current and future sources, along with providing time and cost savings, yet there was very little research on odour dispersion modelling for oil refineries. The OIC are source-specific but OIC for oil refineries has not been well studied. This study investigated odour impact of a conventional oil refinery in Western Canada using the AERMOD model. Odour intensities (OIs) were measured at 62 spots downwind from 70 m to 6.7 km from the plant. Peak to Mean factors (PMF) were generated for the model. The measured OIs were converted to odour concentrations (OC) using OI-OC correlation. Comparison of modelled and measured data indicated that AERMOD predicted the OC satisfactorily (r = 0.67). The model was then used to predict odour impact for this area based on 5-year meteorological data. Comparing dispersion modelling results with the general OIC of the region and odour complaint data, a new set of OIC for the oil refinery was proposed, and the resultant appropriate setback distances for different land uses were predicted by AERMOD. The OIC proposed by this study may be applicable for other refineries yet potential differences in odour acceptance levels of other communities should be considered. The resultant setbacks from this study may not be applicable for sites with different topographic and meteorological conditions.