张艳飞,韩钢城,谢利明,王海学
ZHANG Yanfei,HAN Gangcheng,XIE Liming,WANG Haixue

• 1:内蒙古电力科学研究院
• 2:北方联合电力有限责任公司呼和浩特金桥热电厂

摘要(Abstract)：

蒙西地区7台同型号亚临界参数燃煤火电锅炉相继发生再热器连接管道开裂泄漏失效事件,失效部位多发生于管道焊接接头内壁坡口倒角退刀槽处。对失效试样进行了宏观形貌、显微组织、扫描电镜、化学成分、力学性能、壁厚测量分析,并对7台锅炉设备的设计、运行数据进行调查。结果表明,锅炉燃烧煤种偏离设计煤种、电网AGC负荷自动调度、低氮燃烧改造等因素造成锅炉燃烧和运行工况发生变化,使得再热器减温水居于过量高投入水平,导致再热器微调减温器之后布置的直管和弯头长期承受交变热应力和非周期性振动,最终使管道焊接接头内壁坡口倒角退刀槽应力集中区萌生热疲劳裂纹,并扩展贯通。
Seven coal-fired thermal power boilers with sub-critical parameters of the same type in Western Inner Mongolia have successively suffered from cracking and leakage failures of the reheater connecting pipes, most of which occurred at the chamfered grooves of the inner wall groove of the pipe welding joints. In order to find out the cause of cracking,typical failure samples are intercepted and analyzed for macro-morphology, microstructure, SEM, chemical composition,mechanical properties, wall thickness measurement and design and operation data of seven boiler equipment are investigated.The results show that comprehensive factors such as the deviation of burning coal type from design of boiler, automatic dispatching of AGC load in power grid, low nitrogen combustion transformation caused changes in boiler combustion conditions and operation, which results in excessive high input level of reheater cooling water, therefore making long-term alternating thermal stress and non-periodic vibration of straight pipe and elbow arranged after fine-tuning of desuperheaterflow direction in reheater. As a result, thermal fatigue crack initiated in the stress concentration area of chamfered back tool groove of the inner wall of pipe weld joint and expanded.

关键词(KeyWords)： 锅炉;再热器;连接管道;减温器;热应力;非周期振动;疲劳裂纹
boiler;reheater;connecting pipe;desuperheater;thermal stress;non periodic vibration;fatigue crack

Abstract:

Keywords:

基金项目(Foundation): 内蒙古电力科学研究院科技项目“基于因子关联技术的电站金属设备大数据分析和可靠性评价研究”(ZC-2018-05)

作者(Author): 张艳飞,韩钢城,谢利明,王海学
ZHANG Yanfei,HAN Gangcheng,XIE Liming,WANG Haixue

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