18-8系列粗晶不锈钢锅炉管内壁氧化皮大面积剥落防治对策  

Countermeasures against massive exfoliation of oxidation scale on the internal surface of coarse grained 18-8 type stainless steel boiler tubes

作　　者：贾建民[1] 陈吉刚[1] 李志刚[1] 曹杰玉[1] 吴生来[1] 牟春华[2] 张义政[2] 王胜[2] 

机构地区：[1]西安热工研究院有限公司,陕西西安710032 [2]华能日照电厂,山东日照276826

出　　处：《中国电力》2008年第5期37-41,共5页Electric Power

摘　　要：对18-8系列粗晶奥氏体不锈钢过热器和再热器蒸汽侧氧化皮快速生长和大面积剥落行为及其防治对策进行了研究。结果表明:超温或运行中管壁金属温度偏高是导致蒸汽侧氧化皮快速生长的最主要原因;原生氧化皮外层与基体金属间过大的热膨胀系数差异引起的热应力导致了氧化皮的开裂和剥落;大量管子内壁原生氧化皮外层厚度同时达到或超过临界剥落厚度值导致了氧化皮的大面积剥落。防止氧化皮启停炉时大面积剥落的措施应从2个方面入手:通过控制管壁金属温度水平降低氧化皮的生长速度,从而推迟氧化皮首次发生剥落的时间并减少其剥落总量;通过运行调整改变氧化皮的剥落方式,使氧化皮在运行过程中就以碎屑状陆续剥落并随蒸汽流带出管屏,避免在停炉时以大片状发生大面积剥落。The rapid growth and massive exfoliation of steam-side oxidation scale were studied, which formed on the internal surface of coarse grained 18-8 type austenitic stainless steel superheater and reheater tubes. Main factors contributing to the problems include the overheat or excessively high temperature of boiler tubes in operation, the excessive stress resulted from the thermal expansion coefficient difference between outer layer of original oxidation scale and the base metal, the thickness of most original oxidation scale reaching or exceeding the critical thickness during the rapid startup or shutdown of boiler. Based on these, the countermeasures against massive exfoliation were proposed, such as decreasing the general oxidation rate by controlling the metal temperature level of all tubes, and changing the exfoliation mode by adjusting the operational conditions of boiler. Thus the outer layer of original scale could be flaked off gradually and blown away immediately with steam during operation.

关 键 词：18-8不锈钢 锅炉管 蒸汽氧化 氧化皮剥落 

分 类 号：TK228[动力工程及工程热物理—动力机械及工程]