Toxic loads and explosion overpressure loads pose grave threats to the offshore oil and gas industry. Many safety measures are adopted to prevent and mitigate the adverse impacts caused by toxic loads and explosion overpressure loads. As a general safety barrier, the process protection system has been widely used but rarely evaluated. In order to assess the barrier ability, the mitigation performance of the process protection system is concerned in this study. Firstly, several chain accidents of H₂S-containing natural gas leakage and explosion are simulated by varying the response time of the process protection system with CFD code FLACS. Qualitative assessment is conducted based on the variation of the dangerous load profiles. Furthermore, the quantitative assessment of the mitigation performance is accomplished by considering its ability in reducing the probability of fatality. Emergency evacuation and no emergency evacuation are considered respectively in the quantitative assessment. The results prove that the process protection system takes effect on mitigating the toxic impact and explosion overpressure impact. The results also demonstrate that although the emergency evacuation may result in a severer explosion load to the operator, the process protection system can mitigate the adverse impacts regardless of whether the emergency evacuation is conducted or not.

有毒负荷和爆炸超压负荷对海上石油和天然气工业构成严重威胁。为了防止和减轻由有毒负荷和爆炸超压负荷造成的不利影响，采取了许多安全措施。作为一般的安全屏障，过程保护系统已被广泛使用，但很少进行评估。为了评估屏障能力，本研究关注过程保护系统的缓解性能。首先，H _2的几起连锁事故通过使用CFD代码FLACS改变过程保护系统的响应时间，可以模拟含S的天然气的泄漏和爆炸。基于危险负荷曲线的变化进行定性评估。此外，通过考虑缓解性能降低致死概率的能力，可以对缓解性能进行定量评估。在定量评估中分别考虑紧急疏散和不紧急疏散。结果证明，该过程保护系统可有效减轻毒性影响和爆炸超压影响。结果还表明，尽管紧急疏散可能会给操作员带来更大的爆炸负荷，