某型燃气轮机低压压气机六级后集气腔裂纹故障原因分析及改进措施

Fault Analysis and Improvement Measures for Cracks in the Gas Gathering Chamber of a Gas Turbine's Low Pressure Compressor Sixth Stage Rear

针对某型燃气轮机低压压气机六级后集气腔裂纹故障,分别进行生产过程检查、焊缝检查及安装应力、焊接残余应力、热应力及振动应力分析。综合分析结果表明:低压六级后集气腔裂纹故障的主要原因为高压压气机前卸荷腔向低压六级放气的管路与机组发生共振,在共振应力和热应力共同作用下产生高周疲劳,最终导致距离法兰较近的焊缝位置发生开裂;放气管经改型和放置支架后,消除了因管路共振产生的疲劳应力,故障得以排除,截至目前,机组已安全运行约1500 h。

Regarding the cracks failure in a gas turbine's low pressure compressor sixth stage rear gas gathering chamber,production process inspection,weld inspection and analyses of installation stress,welding residual stress,thermal stress and vibration stress were conducted separately.The comprehensive analysis results indicate that the cracks failure in a gas turbine's low pressure sixth stage rear gas gathering chamber is caused by resonance from the high pressure compressor front unloading chamber to the low pressure compressor sixth stage vent pipe and the unit,high cycle fatigue occurs under the combined action of resonance stress and thermal stress,and cracking occurs at the weld seam location closer to the flange.The fatigue stress caused by pipe resonance is eliminated and the fault is eliminated after the relief pipe is modified and the support is added.So far,the unit has operated safely for about 1500 hours.