超（超）临界锅炉机组高温氧化案例分析与启示

通过分析影响高温氧化的各项因素,研究了2013年国内600 MW以上等级超（超）临界锅炉机组高温氧化的典型实例。从材料、温度及介质3个方面对锅炉高温氧化及氧化皮剥落的影响进行了梳理和总结。研究发现：① TP347H材质在晶粒度较低的情况下抗水蒸气氧化性能差;② 存在汽温欠温问题的锅炉,往往也容易出现氧化皮早期剥落的问题;③ 制造厂家给出的壁温控制报警值不能有效指导电厂运行控制以防止氧化皮带来的问题;④ 锅炉采用的给水加氧处理工艺与氧化皮大面积剥落没有直接关联。最后,提出了今后高温氧化问题的研究方向和改进措施。

Case Study on High Temperature Oxidation in Supercritical/Ultra-Supercritical Boilers

In this paper, the influencing factors of high temperature oxidation are investigated and analyzed based on the typical high temperature oxidation cases of the supercritical/ultra supercritical boilers with 600-MW and above capacities in 2013. The factors which affect the boiler high temperature oxidation and oxide scale exfoliation are sorted out and categorized from the aspects of tube material, wall temperature and medium composition. The study indicates that, firstly, the material of TP347H with coarse grain size exhibits low resistance to water vapor oxidation at high temperatures; secondly, early oxide scale exfoliation tends to appear when the steam temperature of the boilers is lower than its designed value; thirdly, the alarm level of wall temperature provided by boiler manufactures cannot effectively guide the unit operation to prevent the formation and exfoliation of oxidation scale; and finally, there is no direct relationship between the oxygenation treatment of boiler feedwater and the broad exfoliation of oxide scale. Therefore, the suggestions on further studies and preventive measures on high temperature oxidation are proposed.