超超临界机组再热热段疏水管弯头断裂失效分析  

Fracture Failure Analysis of Drain Pipe Elbow in Reheating Section of Ultra Supercritical Unit

作　　者：陶业成 胡杰 赵月 李文正 王平[3] TAO Yecheng;HU Jie;ZHAO Yue;LI Wenzheng;WANG Ping(Guoneng Boiler and Pressure Vessel Inspection Company Limited,Beijing 102200,China;Beijing Guodian electric research institute testing technology company limited,Beijing 102200,China;School of New Energy and Materials,Southwest Petroleum University,Chengdu 610500,China)

机构地区：[1]国能锅炉压力容器检验有限公司,北京102200 [2]北京国电电科院检测科技有限公司,北京102200 [3]西南石油大学新能源与材料学院,四川成都610500

出　　处：《锅炉技术》2024年第4期73-76,共4页Boiler Technology

摘　　要：为了研究再热热段疏水管弯头断裂的原因,以某火力发电厂1000 MW超超临界机组B侧再热热段疏水管为研究对象,对弯头断裂处及附近位置进行了宏观形貌、金相组织、硬度以及力学性能进行了试验分析,疏水管材质为P92,规格为38.1mm×5mm,工作温度603℃,工作压力4.79 MPa。结果表明:一方面,疏水管温度存在反复变化情况,管壁的膨胀与收缩受到一定程度的约束从而产生热应力循环,疏水管弯头产生疲劳损伤,出现热疲劳裂纹;另一方面,弯头外壁存在凹坑,凹坑处易产生裂纹,同时,弯头位置硬度值超过标准上限,使得弯头抗形变能力降低,在排出凝结水过程中,机组负荷变化和排出凝结水的间歇性致使介质流速发生变化,弯头处振动明显,致使弯头处裂纹进一步发展直至出现断裂。In order to study the cause of fracture of the drain pipe elbow in the reheating section,the drain pipe in the reheating section of the B side of a 1 000 MW ultra-supercritical unit in a thermal power plant is taken as the research object,and the macroscopic morphology,microstructure,hardness and mechanical properties of the fracture site of the bend and its nearby locations are analyzed(drainpipe material:P92,specifications:φ 38.1mm×5 mm,the working temperature:603 ℃,the working pressure:4.79 MPa).The results show that:on the one hand,the temperature of the drain pipe changes repeatedly,the expansion and contraction of the drain pipe wall are constrained to a certain extent,resulting in thermal stress cycle,fatigue damage of the drain pipe elbow,thermal fatigue cracks.On the other hand,there are pits on the outer wall of the elbow,and where cracks are easy to occur.At the same time,the hardness value of the elbow position exceeds the standard upper limit,which reduces the deformation resistance of the elbow.In the process of discharging the condensate water,the load change of the unit and the intermittency of discharging the condensate water lead to the change of the medium velocity,and the obvious vibration at the elbow leads to the further development of cracks at the elbow until the fracture.

关 键 词：超超临界机组 疏水管弯头 热疲劳 振动 

分 类 号：TM621.2[电气工程—电力系统及自动化]