超临界汽轮机再热主汽阀门卡涩分析

Mechanical Jamming Analysis of the Reheat-stop-valve Mechanism in the Supercritical Steam Turbine

汽轮机再热主汽阀是汽轮机组的重要辅机,在动态性能、密封性、可靠性方面都有特殊要求。该类汽轮机再热主汽阀是汽轮机组的重要辅机,在动态性能、密封性、可靠性方面都有特殊要求。该类型阀门机构在冷起动过程中经常发生卡涩,且随蒸汽参数升高,出现故障的概率增大且更加严重,严重影响机组的正常运行。针对机构故障现象与结构特点,对动态行为异常变动进行分析,研究表明冷起动过程中,不同零件物理性能差异导致零件间热量传递速度存在较大差异,引起动静配合要素位置和形状变化,并进一步导致径向间隙和轴向间隙变动,严重影响机构的动力学性能。有限元法用来定量分析机构在冷起动至稳态过程中动态配合要素之间的间隙变化,并分析间隙对阀门机构的动态行为影响,数值分析的结果与电厂中出现的问题是一致的,其实际处理方案则验证该方法的正确性。从改进公差设计和制造精度控制两个方面提出解决该类阀门卡涩的具体方案,对于解决该类工程问题具有重要理论价值和现实指导意义。

The reheat-stop-valve mechanism is a vital auxiliary machine in the steam turbine unit,which has specific requirements in dynamic performance,reliability and tightness.However,mechanical jamming often emerges in such mechanisms during cold start,and the trouble is greater and severer with higher steam parameters.Thus,the normal running requirement of the unit cannot be guaranteed.Abnormal variation of dynamic behavior of the reheat-stop-valve mechanism during cold boot is discussed in view of the failure phenomena and structure feature.Great physical property difference,for example coefficient of heat conductivity,leads to different transmission speed of heat in parts.Then,the radial and axial clearance varies greatly in the process of cold start,which influences dynamic behavior.Finite element method is used to quantitatively analyze the clearance variation from cold-boot to steady state,and dynamic performance is evaluated.The numerical results are consistent with the engineering problems,which are valuable to solving the problems in power plants.A concrete schemes is proposed in respect of improving tolerance design and manufacturing precision control,which has important theoretical value and realistic guiding significance to the solution of such engineering problems.