Background and Goal: Refineries are the main source of various pollutants, including Hydrogen Sulfide (H₂S). Therefore distribution and control processing to meet the environmental standard limits is an important issue in industrial units.The present study was carried out to investigate H₂S concentrations and dispersion patterns originating from incinerators of sulfur recovery units in a gas refinery located in Asaluyeh.
Materials and Methods: In this study, H₂S concentrations exhausted from two incinerators’ stacks and also ambient H₂S concentrations at five monitoring stations in and around the refinery were measured in four seasons from summer 2014 to spring 2015. Moreover, the ambient concentrations and dispersion of H₂S were simulated at average times of 1-hr and 8-hr on 50×50 km² scale using  AERMOD model and the simulated results were compared with the measured ones. Meanwhile, the concentration contour plots and the sensitive regions were determined using GIS.
Results: The simulation results indicated that maximum ambient H₂S concentrations were in 1-h average. Assessment of model performance was performed by comparison of H₂S simulated and measured concentrations using statistical analysis and showed that the correlation coefficients in summer 2014, autumn 2014, winter 2014 and spring 2015 were 0.77, 0.89, 0.75 and 0.8, respectively.
Conclusion: The results of this study showed that the variations of measured concentrations were consistent with those of simulated ones. Meanwhile, the contribution of neighbor industries was determined. Comparision of 8-h H₂S concentrations with OSHA and NIOSH standard limits indicated that there was no significant health risk in this refinery.