采用中心驱动的空气预热器断裂失效分析

发布时间：2019-06-08 15:40

【摘要】：随着回转式空气预热器在现代火电机组的锅炉中作为一种换热设备得到广泛的应用,对预热器围带驱动和中心驱动两种驱动方式优劣的讨论不断增多。围带驱动的特点是,结构简单,即使在润滑条件较差的条件下也能运行,这使得围带驱动的使用寿命较长,但现场安装需要花费较多的时间以组装,焊接,调试围带,保证围带与减速机输出轴上的齿轮啮合;中心驱动装置安装简单省事,但对润滑要求较高,需要定期补充润滑脂。本文以预热器转子结构为研究对象,根据中心驱动预热器转子的结构特点,对转子结构在安装和运行过程中的受力情况进行了受力分析,研究了转子结构的应力分布特点。研究表明,凸耳座外端与径向隔板根部交接处是转子径向隔板的最大受力点,也是扭剪断裂敏感区。在此基础上,以略阳电厂6#炉停机检修的两台中心驱动的空气预热器服役实物为例进行验证研究,检查结果表明,在转子径向隔板根部出现多处裂纹。对发生断裂的部位的采样样本进行断口分析,金相显微试验和材料性能测试等分析工作。结果表明,径向隔板根部发生断裂是除此处承载应力最大以外,还受焊接质量、应力状态、材料的冶金质量等多因素综合影响的结果。经本文的力学分析和试验研究研究结果表明,采用中心驱动预热器转子的隔板根部存在扭剪断裂敏感区,该结果为今后预热器设计时对于传动方式的选择提供了重要的参考意见。
[Abstract]:With the wide application of rotary air preheater as a kind of heat exchanger in the boiler of modern thermal power unit, the advantages and disadvantages of the two driving modes of preheater enclosure drive and center drive are more and more discussed. The characteristic of the belt drive is that it has a simple structure and can run even under the condition of poor lubrication, which makes the service life of the belt drive longer, but the field installation takes a lot of time to assemble, weld and debug the belt. Ensure that the enclosure engages with the gear on the output shaft of the reducer; The installation of the central drive device is simple and labor-saving, but the lubrication requirements are high and the grease needs to be replenished on a regular basis. In this paper, taking the rotor structure of preheater as the research object, according to the structural characteristics of the central drive preheater rotor, the stress distribution characteristics of the rotor structure during installation and operation are analyzed, and the stress distribution characteristics of the rotor structure are studied. The results show that the junction between the outer end of the lug seat and the root of the radial partition is the maximum stress point of the rotor radial partition, and it is also the sensitive area of torsional shear fracture. On this basis, two central driven air preheaters, which are shut down and overhauled in Luoyang Power Plant, are taken as examples to verify the service of two central air preheaters. The inspection results show that there are many cracks at the root of the rotor radial partition. The fracture analysis, metallographic microscope test and material performance test were carried out. The results show that the fracture at the root of the radial partition is not only the maximum bearing stress, but also affected by many factors, such as welding quality, stress state, metallurgical quality of the material and so on. The results of mechanical analysis and experimental study in this paper show that there is a torsional shear fracture sensitive zone at the root of the baffle of the rotor driven by the central drive preheater. The results provide an important reference for the selection of transmission mode in the design of preheater in the future.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM621

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