350 MW汽轮机中压缸膨胀不畅原因分析及处理

Analysis and Treatment of Impeded Expansion of Intermediate Pressure Casing in a 350 MW Steam Turbine

某350 MW超临界汽轮机机组自投产第2年起出现中压缸膨胀不畅的问题,机组冷态启动过程中,中压缸胀差经常接近保护动作值,这导致机组启动时间过长、启动燃料成本高。介绍了中压缸膨胀不畅的主要表现,结合故障排查和解体检修中发现的问题逐级分析故障原因,最终查明问题根源为高压缸排汽管道左右限位装置安装间隙过大。通过检修滑销系统、恢复管道限位装置等一系列措施排除了故障,使汽缸膨胀顺畅自如。研究成果可为类似汽轮机汽缸膨胀不畅故障的排查、分析和处理提供借鉴。

There was impeded expansion in the intermediate pressure casing of a 350 MW supercritical steam turbine unit since its second year of operation,and the expansion difference was often close to the protection action value during the cold start-up of the unit,which resulted in lengthening of start-up time and more fuel cost.The main phenomena of the failure were presented,and analysis was carried out step by step combined with the information got from investigation and disassembly maintenance.The root of the problem was attributed to the exceeded installation gap between the left and right limit devices for the exhaust pipe of high pressure casing.By a series of measures,such as overhaul of sliding pin system and recovery of pipeline limit device,the turbine casing could expand smoothly.The research results can provide reference for the investigation,analysis and treatment for similar expansion failures of steam turbine casing.