大型汽轮发电机组进汽方式对轴系振动特性影响研究

发布时间：2018-01-25 06:10

本文关键词： 汽轮机进汽方式振动重叠度阀序切换　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着科技和工业的快速发展,大型汽轮发电机组在工业生活中扮演着举足轻重的角色。喷嘴配汽方式以其部分负荷下调节汽门节流损失小、响应外界负荷要求速度快和运行经济性好的突出优点,成为定压运行汽轮机的主要配汽方式。所以在试运行期结束后,为了提高机组运行的经济性,应将汽轮机的控制方式从单阀运行切换至顺序阀运行。然而大量工程实际表明：在单阀切换成顺序阀运行后往往出现轴振不稳定、瓦温高和调门晃动等问题,有些机组甚至不能在顺序阀方式下正常运行。由于部分进汽问题涉及到转子动力学、轴承动力特性、阀门优化设计等,所以研究此类故障的机理和解决方案不仅有必要,也很有工程实际意义。本文以某台部分进汽下发生不稳定振动的600MW机组为例,首先利用汽轮机原理及调节级变工况计算,建立考虑一定重叠度的调节级的剩余汽流力计算模型,计算结果显示不同进汽方式下剩余汽流力的值相差很大。然后建立基于Reynolds方程的滑动轴承求解模型,利用有限差分法进行求解,将不同进汽方式下剩余汽流力作用到高压转子上后,发现轴承的载荷和载荷角发生改变,轴承的动力特性也随之改变。最后通过建立汽轮机高压转子-轴承动力特性的有限元分析模型,分析了不同阀序对轴承动力特性的影响,进而对该机组阀序切换时的不稳定振动现象做出合理解释,同时也表明,综合阀序调整和阀门优化能够有效解决机组在阀序切换时的问题。
[Abstract]:With the rapid development of technology and industry, large turbine-generator units play an important role in industrial life. The nozzle steam distribution mode adjusts the valve throttle loss with its partial load. In response to the outstanding advantages of high speed and good operation economy, it has become the main steam distribution mode of the constant pressure steam turbine. So after the trial operation period, in order to improve the economic operation of the unit. The control mode of steam turbine should be switched from the operation of single valve to the operation of sequential valve. However, a large number of engineering practice shows that after the operation of single valve to sequential valve, there are many problems such as instability of shaft vibration, high of watt-temperature and sloshing of adjusting door. Some units can not even operate normally in the sequential valve mode. Due to partial steam intake problems related to rotor dynamics, bearing dynamic characteristics, valve optimization and so on. Therefore, it is not only necessary to study the mechanism and solution of this kind of fault, but also of engineering practical significance. This paper takes a 600MW unit with unstable vibration under some steam inlet as an example. Firstly, by using the principle of steam turbine and the calculation of variable working condition of regulating stage, the calculation model of residual steam flow force of regulating stage considering certain overlap degree is established. The results show that there is a great difference in the residual steam flow force in different steam intake modes. Then a sliding bearing solution model based on Reynolds equation is established and solved by the finite difference method. When the residual steam flow force is applied to the high pressure rotor in different inlet modes, it is found that the load and load angle of the bearing are changed. Finally, the influence of different valve sequence on bearing dynamic characteristics is analyzed by establishing the finite element analysis model of high-pressure rotor-bearing dynamic characteristics of steam turbine. Furthermore, the unstable vibration of the unit during valve sequence switching is explained reasonably, and it is also shown that the integrated valve sequence adjustment and valve optimization can effectively solve the problem of valve sequence switching.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM311

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