干熄焦锅炉炉管失效机理分析

Analysis of failure mechanism of coke dry quenching boiler tube

通过对干熄焦锅炉炉管及腐蚀产物开展系统研究,提出炉管失效原因为氧化/硫腐蚀+高温粉尘冲刷。长寿命炉管仅耐磨层发生了较为严重的氧化及硫腐蚀,而近基体层发生了轻微氧化及硫腐蚀,基体只发生了轻微氧化;短寿命炉管耐磨层、近基体层以及基体裂纹内均发生了较为严重的氧化及硫腐蚀,且存在珠光体球化、内表面产生全脱碳层等缺陷。推测短寿命炉管存在超温现象,而超温可加剧氧化及硫腐蚀反应。此外,短寿命炉管遭受了较为严重的高温粉尘冲刷,不仅可造成炉管减薄,还会导致炉管表面温度升高。因此,减少循环气体中粉尘量尤其是大颗粒,可有效减弱冲刷以及控制炉管表面温度,是提高炉管使用寿命的关键。

Coke dry quenching boiler tube and the corrosion products were systematically studied,and the failure cause of the boiler tube was proposed,which was the oxygen/sulphur corrosion and scour by high-temperature powder dust.For the tube with long service time,the oxygen and sulphur corrosion severely occurred in the wear-resistant layer and slightly occurred in the interface layer,and only the oxygen corrosion occurred slightly in the metal base.However,the oxygen and sulphur corrosion severely occurred in the wear-resistant layer,the interface layer and the crack in the tube with short service time.Besides,there were also some defects such as pearlite spheroidization and full decarburization layer in the internal surface in the tube with short service time.It was inferred that the boiler tube was overheated,which would aggravate the corrosion of oxygen and sulphur.Furthermore,the boiler tube suffered the scour by high-temperature powder dust,which was another significant cause of tube failure.Reducing the dust amount in the circulating gas,especially coarse particles,would effectively weaken the scour by dust and to control the temperature of the tube surface,which was the key to increase the service life of the tube.