火电厂汽包水位保护系统的安全评估

摘要

为了使我国传统的电力生产过程符合国家及国际标准,需要对火力发电厂中的安全相关系统进行安全评估.针对火电厂典型的安全仪表系统(SIS)--锅炉汽包水位保护系统进行了系统的安全评估,从而确保了其安全功能的有效执行,并对未达到标准的SIS结构及其运行方式进行了相应的修改.确认系统的安全仪表功能(SIF),利用风险矩阵法选择SIF的目标安全完整性等级(SIL);分析并确认系统结构及其操作模式,通过搜集系统设备的失效率数据,利用故障树分析计算系统定量的安全性指标--要求时失效概率(PFD);通过对计算结果的分析给出了系统的改进建议.%In order to make our traditional electricity generating process compliant with national and international standards, safety assessment of safety-related systems for the power plant is required.In this paper, the safety assessment of a typical safety instrumented system ( SIS ) in power plant-boiler drum level protection system is carried on so that the implementation of its safety functions is guaranteed, and then the structure and its operation mode that doesn't meet the standards is modified accordingly.Safety instrumented function (SIF) of the SIS is confirmed and its target safety integrity level (SIL) is selected by means of risk matrix first.Then the quantitative safety index, probability of failure on demand (PFD), is calculated by using Fault Tree Analysis after the SIS structure and its operation mode are analyzed and its failure rate data is collected.Finally, some suggestions are given to improve the SIS safety according to the analyzing results.