基于FFTA-LOPA的化工装置安全仪表系统SIL确定方法

为了优化确定化工装置安全仪表系统（SIS）安全完整性等级（SIL），分析了现有确定SIL的不足，针对化工装置的失效数据缺失和不确定性特点，提出模糊事故树-保护层（FFTA-LOPA）模型计算安全仪表系统SIL。以某低密度聚乙烯反应釜为例，建立了该反应釜爆炸事故树，运用模糊理论定量分析顶上事件发生的概率，最终确定其安全仪表系统安全完整性等级为SIL 1。结果表明:该方法结合两种风险分析理论，分析结果与实际和理论统计结果符合性较好，具有一定地准确性和实用性，可以为定量确定系统SIL提供理论指导。

Study on determination method of SIL for safety instrumented system of chemical plant based on FFTA-LOPA

In order to optimize the determination of safety integrity level (SIL) for safety instrumented system (SIS) of chemical plant, the deficiencies of existing SIL determination were analyzed. Aiming at the characteristics of shortage and uncertainty in failure data of chemical plant, a fuzzy fault tree analysis & layer of protection analysis (FFTA-LOPA) model was proposed to calculate SIL of SIS. Taking a low density polyethylene (LDPE) polymerizing-kettle as example, the explosion fault tree of polymerizing-kettle was established. The fuzzy theory was applied to quantitatively analyze the probability of top event, and the SIL of this SIS was determined to be SIL 1. The results showed that through combining two risk analysis theory, the analysis results of this method had better compliance with practical and theoretical statistical results. It has certain accuracy and practicability, and can provide theoretical guidance for quantitative determination of SIL.