Abstract: Cracks were found in the blades of axial-flow fan of a FCC unit during maintenance. 222 rotor blades were detected by phased array detection technology, and 109 of them had strip defect cracks with a length of 3~29 mm. The open cracks found in the blades root were mainly distributed in the exhaust edge of the non-working face with low stress, not in the working face with direct stress. The optimal reinstallation method of the axial-flow fan blades was made. Reasonable base blades were determined at each stage, the height of the base blades was measured accurately, and the blades were cut and machined accurately. The deviation between the blades’ height and the base blades’ height was controlled within ±0.05 mm. Frequency of each blade was measured after improvement, and the frequency dispersion of blades at each stage was less than the standard requirements, and the axial-flow fan ran smoothly.

Key words: FCC unit, axialflow fan, rotor blade, crack, stress analysis, material defect, fatigue cracking, reinstallation scheme

摘要： 介绍了某催化裂化装置轴流风机在检修中发现叶片出现裂纹的情况:222件动叶片应用相控阵检测技术检测，109件存在条形缺陷裂纹，长度3～29 mm，叶根发现的开口裂纹主要分布在受力偏小的非工作面的排气边，并不在直接受力的工作面。优化分析后改进了轴流风机叶片的回装方案：每级确定合理基础叶片，测准基础叶片高度，利用三维坐标机床精确切削和加工新叶片，控制叶片高度与基础叶片高度偏差小于±0.05 mm。改进后对每片叶片进行测频，每级叶片频率分散度均小于标准要求，且轴流风机运行平稳。

关键词: 催化裂化装置, 轴流风机, 动叶片, 裂纹, 受力分析, 材质缺陷, 致疲劳开裂, 回装方案