省煤器夹套式热管爆破的原因

某五段省煤器夹套式热管在运行过程中发生爆破,导致泄露;从化学成分、显微组织、硬度、断口形貌等方面对夹套式热管的爆破原因进行了分析。结果表明:在第一次开工时该热管在400℃左右超温运行,蒸汽压力超过其爆破压力导致外管开裂;外管开裂后,管内水介质及内外管间工质流出,冷却作用下降,高温烟气直接接触内管,增加了硫酸露点腐蚀的可能性,导致继续运行3个月后内管发生破裂;在实际运行中,应严格控制操作工艺,加强运行管理,杜绝管道超温,以防同类失效再次发生。

Burst Cause of Jacketed Heat Pipe in an Economizer

Jacketed heat pipe of a five-stage economizer bursted during the operation,leading to leakage.The burst cause of the jacketed heat pipe was analyzed from the aspects of chemical composition,microstructure,hardness,fractography,etc.The results show that at the first start of operation,the heat pipe worked at an overheating temperature about 400℃.The steam pressure exceeded the burst pressure,causing the cracking of the outer pipe.After the outer pipe cracked,the water in the pipe and the working medium between the inner and outer pipes flew out,reducing the cooling effect;the high temperature flue gas directly contacted the inner pipe,increasing the possibility of sulfuric acid dew point corrosion.Consequently,the burst of the inner pipe occurred after continuously running for three months.In actual operation,the operation process should be strictly controlled and the operation management should be strengthened to prevent the pipeline from overheating,thus preventing the similar failure from happening again.