1025 t/h锅炉末级过热器频繁爆管机理研究

Study on Mechanisms of Frequent Tube Failure of the Final Superheater for a 1025 t/h Boiler

为了有效的预防和控制锅炉实际运行中受热面爆管和氧化皮剥落的问题,对1 025 t/h末级过热器的102钢管材做了力学性能分析和金相分析,并对氧化皮进行了厚度测试和能谱分析。结果表明:运行11.5万小时后管材的常温力学性能能保持在要求范围内,但晶界聚集了较多的碳化物颗粒,并且逐渐连接成链状,组织呈现一定的老化倾向;长时间超温运行,导致部分氧化皮有了明显的剥落倾向;汽温大幅波动是氧化皮剥落的重要原因;水蒸汽不断透过各氧化层的孔洞深入层基体,使得氧化不断向内侧发展;优化运行方式可有效控制氧化皮形成和脱落且成为主要手段。

In order to prevent and control heating surface tube failure and oxide scale falling off for actual operation boilers,mechanics property analysis and metallographic analysis are carried out with 102 steel tube stock for 1 025 t/h final superheater. Meanwhile the thickness measurement and energy spectrum analysis are performed for the oxide scale.The results show that tube stock can meet the mechanics property requirement after running 115 000 hours,but large amount of carbide particles are collected in grain boundary,which gradually connect each other and form a chain. The organizations of tube stock present a certain aging tendency. The apparent falling off tendency is caused by running at over-temperature for a long time. The high steam temperature volatility is an important reason for oxide scale falling off. Steam constantly penetrates into basal body through the hole of oxide scale. Oxidation expands further inside the basal body. Optimizing the operation mode is a main method to control the formation and falling off of oxide scale.