电站锅炉承压部件失效模式分析

Failure mode analysis for the pressurebearing components of the power-generating boiler

为了将故障模式影响和危害性分析FMECA(Failure Mode Effects and Criticality Analysis,FMECA)与故障树分析FTA(Fault Tree Analysis,FTA)故障模式失效理论引入电站锅炉承压部件安全工程评定领域,建立了以电站锅炉承压部件失效模式分析的正向FTF(FMECA To FTA,FTF)分析模型,对电站锅炉承压部件进行模糊FMECA综合评价。分析了电站锅炉承压部件的失效机理和多因素影响,确定了承压设备的评价因素集合和模糊评价矩阵,以及各级指标因素权重分配的规则,并对电站锅炉承压部件失效的综合评判矩阵模型进行一级评价。采用模糊综合评价的危害度分析CA(Criticality Analysis,CA)结果提供底事件概率并开展定性、定量FTA,以此对电站锅炉承压部件系统失效的发生概率、危害严重程度进行故障模式分析,选择电站锅炉承压部件的故障模式作为顶事件建立事故树,采用Bow-tie模型对电站锅炉蒸汽管道、给水管道、省煤器管、过热器及再热器管、水冷壁管、高温集箱、减温器、锅筒、启动分离器9类主要承压部件失效进行定性和定量分析。结果表明,通过正向FTF法将Bowtie模型引入风险致因并与危害后果相关联,对FMECA进行了系统全面的补充,从而进一步推进了该方法在电站锅炉承压部件系统安全可靠性及失效模式分析中的应用。

The given paper is inclined to introduce a failure mode analysis for the pressure-bearing components of the power-generating station boiler in hoping to bring the theory of Failure Mode Effects and Criticality Analysis（ FMECA） in addition to the Fault Tree Analysis（ FTA） into the safety engineering assessment on the pressure-bearing components of the power station boiler. For the above mentioned purpose,we have first of all done the fuzzy FMECA comprehensive evaluation on the pressure-bearing components of the power station boiler along with an analysis of the failure mechanism and the influential factors of the pressure-bearing components of the power station boiler. In doing so,we have first of all identified and determined all the evaluation factors involved,assigning the fuzzy evaluation matrix and the rules for the factors weights at all levels. And,then,we have done objective assessments very carefully by using the comprehensive evaluation model of the pressure-bearing components failure of the power station boiler. At the same time,we have also carried out the fault tree analysis both from the qualitative and quantitative points of view in the regard of the bottom event probability from the Criticality Analysis results of the fuzzy FMECA comprehensive evaluation. At the same time,we have also analyzed the failure mode of the failure incidence probability and the damage severity in that system of the boiler. Since the fault tree has been built with the failure modes of the pressure-bearing components of the power station boiler as the top events,we have done such failure analysis of the pressure-bearing components（ including the steamtransmitting pipes,the water-feeding pipes,the economizer tube,the superheater the reheater tube,the water-cooling wall tubes,the high temperature producer,the desuperheater tube,the boiler＇s shell,and the start-up separator） of the power station boiler both qualitatively and quantitatively through the Bow-tie model.All the results of the aforementioned analysis and investigation demonstrate that the damage consequences are mainly caused by means of the forward FTF model along with the Bow-tie model.Therefore,it has been proved to be both possible and realistic on the condition that the successful applications of the theory of the FMECA and the Fault Tree Analysis（ FTA） method can be made sure to guarantee the systematic safety and reliability of the pressure-bearing components of the power station boiler as a whole by applying the above said theory to cope with the related accidents.