■  Prevention and Mitigation Systems using CFD Simultion

  A mitigation system is significant in that it blocks the flow of toxic gas and prevents the growth of hazardous areas, thereby securing sufficient evacuation time. A new air curtain mitigation system was developed to prevent the dispersion of toxic gas by breaking the momentum of flow and reducing the extent of the affected region.

  A three-dimensional computational fluid dynamics (CFD) was used to investigate both physical and chemical effects of the water curtain as a release mitigation system for SiCl4. Once the water curtain works, the concentration of SiCl4 rapidly decreases due to the chemical reaction with water and its concentration reaches the ERPG-2 of 5 ppm at about 570 m.

  Current containment facility regulations focus on preventing overflow by requiring protective walls with 110% of the tank volume, but lack provisions for mitigating overtopping caused by wave action during hazardous material leaks. the effectiveness of optimized overtopping prevention structures was investigated in mitigating the spread of hazardous materials such as styrene during accidental releases using CFD simulation.

  Ensuring early leak detection and implementing effective secondary containment systems are critical for preventing the dispersion of hazardous liquids and minimizing the casualties of a chemical accident. The proposed detection method and optimized separation distance hold the potential to facilitate a revision of liquid storage and handling standards grounded in robust scientific and quantitative evidence. 

  The extent of casualty and property loss due to chemical accidents depends on how well the emergency action plan was established in advance and how fast the warning notice and evacuation orders are given to the public. Five key parameters, report time, toxic cloud arrival/removal time and indoor/outdoor concentration, are selected for the evacuation decision, and the effectiveness of leakage and wind speed on five parameters is investigated.  

  The effective evacuation strategy according to the accident scenario is crucial to minimize human casualties in the event of toxic gas leak accidents. The effect of the building direction and the industrial complex location on the increase in indoor concentration and outdoor diffusion was examined under the same leakage conditions, and effective evacuation criteria were established.