回座冲击对安全阀阀座应力分布及塑性变形的影响

发布时间：2019-04-21 17:45

【摘要】：安全阀是承压系统重要的保护装置之一,其重要的技术指标是需要保持良好的密封性能,然而实际情况中,安全阀的密封面经常因为加工的缺陷、回座冲击变形过大等原因造成安全阀的密封效果达不到要求。为此,本文采用有限元模拟和中子衍射测量技术、三坐标仪测量技术对安全阀阀座的应力分布和塑性变形进行了计算模拟和实验测量验证。研究的主要内容及结论如下： (1)采用达朗伯原理解析计算安全阀回座冲击的时间,研究安全阀阀瓣尺寸、阀瓣类型以及回座冲击速度对冲击时间的影响,发现安全阀的回座冲击时间主要与安全阀冲击接触面的尺寸以及阀瓣的刚性有关。 (2)采用有限元模拟不同阀瓣结构的安全阀密封性能以及对回座冲击缓冲效果,发现采用刚性较小的阀瓣,安全阀的密封性能较好,采用弹性阀瓣能对回座冲击进行有效缓冲,有利于安全阀的长期稳定运行。 (3)采用有限元模拟和中子衍射测量技术、三坐标仪测量技术对冲击速度和次数对安全阀阀座的应力分布和塑性变形的影响进行了研究,发现当阀瓣与阀座接触时速度为3m/s,进行4-10次的预冲击能将安全阀阀座原有的残余拉伸应力降到最低,有利于安全阀服役寿命提高,同时发现600次回座冲击下,密封面及阀座的塑性变形可以忽略,对安全阀密封性能和整定压力的影响可以不计。据此,提出采用预冲击改善安全阀阀座结构完整性的设想和原则。
[Abstract]:Safety valve is one of the important protective devices in pressure-bearing system, and its important technical index is to maintain good sealing performance. However, in practice, the sealing surface of safety valve is often due to the defects of machining. The sealing effect of the safety valve can not meet the requirements due to the excessive impact deformation of the return seat. Therefore, the stress distribution and plastic deformation of the safety valve seat are simulated and verified by using the finite element simulation and neutron diffraction measurement technique and the three-coordinate measuring technique. The main contents and conclusions of the study are as follows: (1) the impact time of safety valve return seat is calculated analytically by using Daramber principle, and the influence of valve disc size, disc type and return impact speed on impact time is studied. It is found that the impact time of the return seat of the safety valve is mainly related to the size of the impact contact surface of the safety valve and the rigidity of the disc. (2) using the finite element method to simulate the sealing performance of the safety valve with different disc structure and the impact buffering effect on the return seat, it is found that the sealing performance of the safety valve is better with the less rigid disc. The use of elastic disc can effectively cushion the impact of the return seat, which is conducive to the long-term stable operation of the safety valve. (3) the influence of impact velocity and times on stress distribution and plastic deformation of safety valve seat was studied by using finite element simulation and neutron diffraction measurement technique and three coordinate measuring technique. It is found that the original residual tensile stress of the safety valve seat can be minimized when the disc is in contact with the seat at a speed of 3 m / s, and the original residual tensile stress of the safety valve seat can be minimized when the disc is in contact with the seat. At the same time, it is found that the service life of the safety valve can be improved when the valve disc is in contact with the seat. Plastic deformation of sealing surface and seat can be ignored, and the effect on sealing performance and setting pressure of safety valve can be ignored. Based on this, the idea and principle of using pre-shock to improve the structural integrity of safety valve seat are put forward.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TH134

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