Chlorine Poisoning Risk Management Based on ALOHA Simulation

ABSTRACT In this paper, based on the investigation report of a liquid chlorine leakage accident during filling operation, ALOHA software was used to simulate the indoor and outdoor chlorine gas diffusion in different accident scenarios, and the emergency evacuation area was divided according to the different toxicity levels. A four-step method for risk assessment was used to identify the occupational hazards of liquid chlorine leakage in the process of liquid chlorine filling. The dose-response model of acute chlorine poisoning was selected to characterize the individual risks of different exposure concentrations and exposure durations. Different measures were taken to manage the risks depending on whether they were tolerable. It was verified that according to the accident investigation report information, the chlorine gas diffusion simulated by ALOHA were basically consistent with the actual casualties of personnel in the two surrounding companies. The concentration of chlorine gas in buildings with low ventilation rate was much lower than that outdoors. The risk for individual exposed to 235mg/m3 chlorine for less than 10 minutes, to 136mg/m3 chlorine for less than 30 minutes, or to 96mg/m3 chlorine for less than 60 minutes is tolerable. Risk management strategies vary depending on whether the risk is tolerable. The diffusion simulation results based on ALOHA have guiding significance for selecting the locations of crowded places in plant area, chemical industrial park and surrounding enterprises. In case of accident leakage, people in the downwind area to which poison gas has spread should first evacuate to the vertical wind direction and then escape to the upwind direction. If there is no respiratory protection, they should close the doors and windows and wait for rescue.