保护层分析中独立保护层的识别研究

Study on Identification of Independent Protection Layers in Layer of Protection Analysis

为阐述保护层分析(LOPA)中独立保护层(IPL)的识别规则,以及这些规则在实际应用中要注意的问题,以生产聚氯乙烯(PVC)的间歇聚合反应为例,对8个不同的LOPA场景进行分析,给出不同场景的IPL和要求时的失效概率(PFD),以及建议增加的IPL。分析结果表明,在进行IPL的识别时,应重点确认IPL的有效性和独立性。在评估IPL有效性时,应关注具有共同元件的IPL,IPL的行动能力、人员行动有效性及IPL的PFD等。在评估独立性时,应确保IPL独立于初始事件和同一场景中的其他IPL的任何构成元件。通过分析,发现PVC工艺中安全阀(PSV)设计、安全仪表功能(SIF)设计和人员行动等IPL中存在的问题,并提出相应的建议。

In order to investigate the rules which are used to identify the IPL in LOPA and the problems that should be paid attention to when these rules were applied,this paper analyzed eight different LOPA scenarios in a batch polymerization of polyvinyl chloride（PVC） production.The IPLs and their PFD of different scenarios were provided.The IPLs that should be added were suggested too.The results show that the effectiveness and independence of IPL should be confirmed when identify the IPL.The IPL with common components,the IPL＇s action ability,the effectiveness of human action and IPL＇s PFD should be focused when assessing the effectiveness of IPL.When the independence of IPL is assessed,the IPL independent of the initiating event and the components of any other IPL already claimed for the same scenario should be assured.The problems which exist in pressure safety valve（PSV）,safety instrumented function（SIF） system design and human action IPLs were discovered,and corresponding solutions were proposed.