300MW机组汽轮机高压进汽插管断裂故障分析及处理

ANALYSIS OF RUPTURE FAULT OCCURRED ON PLUG-IN PIPE FOR HP STEAM INCOMING TO 300 MW STEAM TURBINE

某电厂4号300MW机组汽轮机运行中出现异音,大修解体发现高压进汽插管断裂并严重损坏。对高压进汽插管结构进行的试验分析表明,高压进汽插管原设计为两道密封环密封结构,后改为钟型罩密封,但在钻紧定螺钉的螺孔时,造成销孔部分螺纹缺失而使紧定螺钉脱落和专用销退出,使插管失去水平方向的活动裕量,在热应力的作用下插管承受较大力矩断裂而导致异音。对此,将断裂和存在缺陷的进汽插管进行了更换,加固了紧定螺钉,并提出了进一步的防范措施。

Abnormal noise occurred in operation of 300 MW steam turbine equipped for unit no.4 in one Power Plant.In disassembled major repair,the plug-in pipe for HP steam incoming has been discovered to be ruptured,and being seriously damaged.Test and analysis for the structure of said plug-in pipe show that the structure of said plug-in pipe was originally designed with two sealing rings,and later being retrofitted into bell-shaped seal,but during the time of drilling screw hole,a partial of screw threads of the pin hole have been damaged,making the fastening screw to be drop-off,and the special pin to be out from its position,and the plug-in pipe to lose movement allowance in the horizontal direction,finally the plug-in pipe is ruptured due to bearing large moment of force under the effect of thermal stress.For this,the ruptured plug-in pipe and that with defects have been replaced,reinforcing the fastening screw,and further preventive measures being put forward.