超超临界机组锅炉减温器典型失效案例分析Analysis of Typical Failure Cases of Boiler Desuperheater for Ultra-supercritical Units
徐绍平,王贤明,彭以超,楼玉民
XU Shaoping,WANG Xianming,PENG Yichao,LOU Yumin
摘要(Abstract)：
喷水减温器是目前超超临界机组重要的汽温调节方式,通过对近几年超超临界机组中出现的典型减温器结构(包括旋涡式、多孔喷嘴式以及莫诺克式等)失效案例进行分析,研究造成其断裂失效的机理。结果发现:低温减温水与减温器喷嘴之间温差大,导致减温器喷嘴产生巨大的温差热应力是造成减温器出现裂纹的主要原因。低温减温水投用频繁,造成减温器内壁出现骤热骤冷的交变应力,加快了减温器的热疲劳失效。另外,部分减温器设计不合理,如喷水管存在膨胀受阻、结构突变或与集箱存在横向间隙,从而导致喷水管振动加剧产生机械疲劳开裂,这也是某些结构的减温器失效的重要原因。
Spray desuperheater is an important way to regulate the steam temperature of ultra-supercritical units. In this paper, the cases of several typical desuperheater structure failures(vortex, multi-hole nozzle and Monok type, etc.) in recent years are analyzed, and the corresponding failure mechanism is also studied. It is found that the main cause of cracks in the desuperheater is the large temperature difference between the desuperheating water and the nozzle, which results in huge thermal stress. The frequent application of desuperheating water leads to alternating stress on the inner surface, which further accelerates thermal fatigue failure. In addition, the design of some desuperheaters is unreasonable, such as the blocked expansion of the nozzle, sudden structural changes or horizontal gap from the header, resulting in increased vibration and mechanical fatigue cracking, which is also an important cause for the failure of some desuperheaters.
关键词(KeyWords)：
超超临界机组;减温器;失效分析;热疲劳;机械疲劳;断裂
ultra-supercritical unit;desuperheater;failure analysis;thermal fatigue;mechanical fatigue;fracture
基金项目(Foundation): 浙能集团科技项目(ZNKJ-2016-001)
作者(Author):
徐绍平,王贤明,彭以超,楼玉民
XU Shaoping,WANG Xianming,PENG Yichao,LOU Yumin
DOI: 10.19585/j.zjdl.201812018
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