The mitigation performance of ventilation on the accident consequences of H2S-containing natural gas release

Abstract Ventilation is an available measure to dilute the released toxic gas and has been widely applied in offshore facilities to mitigate the adverse impact. However, “available” is never the same as “effective”. Up to now, the mitigation performance of ventilation remains a challenging topic that needs to be further studied. To identify the effectiveness of the mitigation, a systematic approach is proposed concerning the toxic impact caused by the diluted toxic gas, during which the emergency evacuation is considered. The grid-based concept is adopted to identify the initial position with the worst toxic impact. Then the effectiveness of ventilation is estimated according to its ability on mitigating the worst toxic impact. Taking an offshore platform as a case, the toxic impact under different H2S leakage scenarios are predicted. The dependencies among the wind speed, leakage rate, concentration of H2S, and toxic impact are discussed. Some safety-related results can be obtained, such as accident scenarios where ventilation can effectively mitigate the toxic impact. The present work could provide guidance to improve the safety of design and emergence plans in H2S release accidents.