350MW超临界汽轮机冷态启动中压缸胀差大的分析及处理

Analysis and Treatment on the Excessive Expansion Difference of Medium Pressure Cylinder During the Cold Start-up in a 350 MW Supercritical Steam Turbine

某电厂5号和6号350 MW超临界机组汽轮机投运以来冷态启动过程中一直存在中压缸胀差偏大的问题,造成机组启动时间过长和脱硝系统不能及时投入运行。分析中压缸胀差偏大的原因后,采用调整轴系K值、增加中压缸夹层加热系统、优化冷态启动过程等措施。结果表明:采取相应的措施后,2台机组汽轮机冷态启动过程顺利并能按启动要求带满负荷。

For the 350 MW super critical units in a power plant,the expansion differences of the medium pressure cylinders were excessive during the cold start-up of the steam turbines in the No.5 and No.6 units,which leads to the long start-up time of the units and the operation delay of the denitration system.Analyses were conducted on the excessive expansion differences of the medium pressure cylinders,and following corresponding measures were carried out,such as adjusting the K value of the shaft clearance,adding the heating system between the inner-shell and outer-shell of the medium pressure cylinder,optimizing the cold start-up process,etc.Results show that,through adopting corresponding measures,the cold start-up processes of the steam turbines in the two units are smoothly,and the units can reach full load with the start-up requirements.