More than thirty-five years ago, the Bhopal disaster shook the whole world and investigators found out that many people survived just because they turned on the fans in their bedrooms. It was postulated that the forced ventilation played an important role in diluting the toxic gas and saved these people. In order to provide evidence to solve this old mystery, this research employed FLACS software to assess the hazardous degree of a toxic gas (hydrogen sulfide) leakage within a petrochemical process. Series of gas dispersion simulations were performed to actualize the hazardous characteristics and the corresponding risks of the release accident. The study shows that the hazardous level and the hazard range can be greatly influenced when parameters, such as the gas leakage circumstances (atmospheric conditions and wind speed) and the mitigation measures (direction of fans and their speed) are altered.

By using explosion-proof fans in different positions and ventilation directions, combined with the natural wind in a certain direction, this research attempts to detect the best combination from various mitigation designs and to compare the influence of fan directions on hazard mitigation. It is also the first time of its kind to simulate the effect of forced ventilation on hazard mitigation within a process plant. The results show that the hazardous level of a toxic release can be effectively alleviated, when the direction of the mechanical ventilation is against the natural wind direction. With the help of the CFD simulation and the quantitative risk analysis technique, different loss prevention strategies can be tested via this method in order to establish a safer working environment.

三十五年前，博帕尔灾难震惊了全世界，调查人员发现许多人幸存下来只是因为他们打开了卧室的风扇。据推测，强制通风在稀释有毒气体和挽救这些人方面起着重要作用。为了提供证据来解决这个古老的谜团，本研究使用FLACS软件评估了石化过程中有毒气体（硫化氢）泄漏的危险程度。进行了一系列气体扩散模拟，以实现危险特性和释放事故的相应风险。研究表明，当参数，

通过在不同位置和通风方向上使用防爆风扇，并在一定方向上结合自然风，本研究试图从各种缓解设计中找出最佳组合，并比较风扇方向对减轻危害的影响。这也是同类产品中首次模拟强制通风对加工厂内减轻危害的效果。结果表明，当机械通风的方向与自然风向相反时，可以有效地减轻有毒物质释放的危险程度。借助CFD模拟和定量风险分析技术，可以通过此方法测试不同的损失预防策略，以建立更安全的工作环境。