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为保证锅炉燃烧系统的安全,防止发生锅炉爆炸事故,需要对火电厂炉膛安全监控系统(FSSS)的关键安全功能主燃料跳闸(MFT)进行安全评估。基于IEC 61508标准框架和功能安全评估技术定量评估了MFT的子功能--炉膛负压高连锁保护停炉的可靠性与安全性。首先,采用定性分析方法,确定了目标安全完整性等级;其次,综合考虑共因失效和诊断两个重要影响因素,构建了危险失效故障树;再次,结合电厂相关设备失效数据,计算了平均要求时失效概率,确定了其安全完整性等级;最后,分析了影响MFT安全性的因素,总结了目前火电厂MFT功能设计中可能存在的问题。
In order to ensure the safety of the boiler combustion system and prevent the occurrence of a boiler explosion, a safety assessment of the main safety fuse (MFT), a key safety function of a furnace power plant safety monitoring system (FSSS), needs to be carried out. Based on the IEC 61508 standard framework and functional safety assessment techniques, the sub-functions of MFT are quantitatively evaluated - the reliability and safety of furnace underpressure interlock protection with shutdown. First of all, using the method of qualitative analysis, the safety integrity level of the target is determined. Secondly, considering the two important factors of common cause failure and diagnosis, a fault failure tree is constructed. Thirdly, the average requirements The probability of failure is determined and its safety integrity level is determined. Finally, the factors that affect the safety of MFT are analyzed, and the possible problems in the design of MFT function in thermal power plant are summarized.