Atmospheric odor dispersion from oil refinery flare system: a case study.

Abstract

A flare stack is an indispensable device in the oil and gas industry for allowing the safe combustion of gases into the atmosphere, especially during emergencies. However, it is not ideal for the routine disposal of gaseous waste, as it is subject to meteorological influences and poor operational control. In addition, it can be affected by toxic currents and thus pose a potential risk of odors; in view of this, an assessment must be made of the implications of burning on the environment and health. Atmospheric dispersion modelling has proved to be a very useful tool for this purpose. In light of this, an attempt has been made in this work to evaluate the impact of H2S on the well-being (odor perception) of the community in the surrounding area of an oil refinery, where the temporary burning of rich gas in H2S occurs in a chemical flare, and operational factors have an influence on atmospheric dispersion. The odor assessment was carried out with the aid of AERMOD which was adapted to estimate the maximum odor concentration for very short periods by means of peak-to-mean ratios. The results showed that H2S detection can reach a probability rate of 42% at 3.5km distance from the flare (in a time interval of 5s) with a relatively high degree of annoyance (3.0 AU). However, some operational procedures can reduce the probability of odor detection to 29% and the degree of annoyance to 2.6 AU.