Evaluation of hazard distances related to toxic releases in a gas refinery: comparison of chemical exposure index and consequence modeling approaches.

The release of toxic chemicals is an important hazard of chemical plants. The purpose of this study is to compare the chemical exposure index (CEI) and consequence modeling to determine the hazard distance of toxic chemical release, utilizing a gas refinery as the case study. The CEI was utilized and considerable release scenarios were determined. The process hazard analysis software tool model was performed for consequence modeling of the scenarios with the highest airborne quantity. In the case of toxic chemical release based on both the CEI and consequence modeling, the sludge catcher unit was identified as the most dangerous unit. Hazard distances calculated by the CEI are significantly greater than those using consequence modeling. This is acceptable in terms of safety, but may not be applicable in reality. The results of the study showed a procedure for selecting an appropriate method in order to reduce costs and time.