超临界循环流化床锅炉高温过热器管开裂原因分析  

Cause analysis for cracking of high temperature superheater tubes in supercritical circulating fluidized bed boiler

作　　者：赵平 Zhao Ping(Guangxi Branch,Aluminum Corporation of China Limited,Pingguo Guangxi 531499,China)

机构地区：[1]中国铝业股份有限公司广西分公司,广西平果531499

出　　处：《金属热处理》2021年第6期225-230,共6页Heat Treatment of Metals

摘　　要：某超临界循环流化床锅炉TP347H钢膜式壁高温过热器管频繁发生开裂,通过宏观检查、光谱分析、力学性能试验、显微组织分析以及运行情况分析等对其失效原因进行了研究。结果表明,取样管化学成分、力学性能均满足标准要求,显微组织未见异常;裂纹起源于管子与鳍片焊趾处,并从外壁向内壁扩展;管子开裂原因为:高温过热器管为大屏膜式壁结构,加之锅炉启动过程中,相邻管壁温度差较大且不断变化,造成管子在轴向方向的膨胀差较大并形成交变热应力,从而在焊趾应力集中部位产生热疲劳裂纹,同时管子与鳍片焊缝处的残余应力以及管子外表面存在的直道沟槽促进了裂纹的形成和扩展。High temperature superheater tube with TP347H steel membrane wall of one supercritical circulating fluidized bed boiler cracked frequently.The failure reasons were investigated by means of macroscopic examination,spectral analysis,mechanical property test,metallographic analysis and operation analysis.The results show that the chemical composition and mechanical properties of the sampled tubes meet the technical requirements of standard,and the metallographic structure is normal.The cracks originate from the weld toe between the tube and the fin and extend from the outer wall to the inner wall.The high-temperature superheater tube has a large-screen membrane wall structure.During the boiler start-up process,the temperature difference between adjacent tube walls is large and constantly changing,resulting in a large expansion difference in the axial direction of the tube and formation of alternating changes.So the thermal fatigue cracks initiate at the stress concentration position of weld toe.The welding residual stress in the weld toe and the straight groove on the outer surface of the tubes promote the formation and propagation of cracks.

关 键 词：循环流化床锅炉 高温过热器 TP347H钢 膜式壁 温差 热疲劳裂纹 

分 类 号：TK223[动力工程及工程热物理—动力机械及工程]