【摘要】 超超临界塔式锅炉T23水冷壁运行一段时间后,多处焊缝出现不同程度的泄漏,严重影响机组的安全性。断口分析发现轴向拉应力产生的环向裂纹在热疲劳作用下导致了接头泄漏。通过有限元分析软件ABaqus模拟了T23水冷壁管的焊接过程,获得焊接残余应力分布场,在此基础上研究了强制对口产生的装配应力对T23水冷壁管焊接接头应力场的影响,发现强制对口严重影响焊接接头处的应力,极易造成T23水冷壁焊接接头的失效泄漏。从许用应力角度给出了强制对口所能承受的最大弯矩,为存在错边问题的T23水冷壁焊接施工规范提供了参考依据。最后对水冷壁温度波动产生的热疲劳行为进行了分析,结果表明热疲劳是环向裂纹扩展的关键因素。更多还原

【Abstract】 The pipeline leakage in T23 water wall of ultra-supercritical tower boiler was found after the units had been put into operation for a period of time, which seriously affected the safety of the boiler units. Fracture analysis found that the circumferential crack that caused by the axial tensile stress is the main factor for the weldment leakage.Welding process of T23 water wall tube was simulated by finite element analysis software ABAQUS, and the welding residual stress distribution field was obtained. On this basis, the influence of the assembly stress on the stress field of the welded joints of the T23 water wall tube was studied. The results show stress on the welded joints is seriously affected by the assembly stress, which could cause the leakage of the T23 water wall welded joints. The maximum bending moment can be given according to the allowable stress, which provides a reference for the construction of T23 water wall welding. The thermal fatigue caused by the temperature fluctuation of the water wall is the key factor of the annular crack propagation.更多还原