Application of H2S Dispersion Modelling in an Accident Investigation Process in a Paper and Cellulose Factory

This case consists of carrying out simulations involving the dispersion of a toxic hydrogen sulfide cloud, in order to evaluate and determine the most likely hypothesis for an accident involving accidental release of a product, considering the evidence obtained in the event investigation process. Based on the information collected in the field, the path taken by the victims during the accident was reconstructed - “Travel chart” - and four hypotheses were formulated for the release of the toxic gas.

The time of exposure to the toxic cloud is a parameter that significantly influences the effects on human health, which may involve: detection of a characteristic odor; loss of smell; unconsciousness, convulsion; and/or fatality. In this way, the study evaluated the dynamics of the displacement (dispersion) of the toxic cloud, as well as the movement of victims during the event, factors that directly impact the exposure time.

The criteria established for evaluating each accidental hypothesis formulated involved comparing the toxic dose of hydrogen sulfide calculated in the simulation with the exposure effect observed at each point of interest identified by the “Travel chart”. Such analysis was essential to support the organization during the investigation process in understanding the event that occurred, as well as in defining the most likely hypothesis related to the point at which the leak occurred.