超低温球阀主密封副性能研究及热力耦合分析

发布时间：2018-03-21 03:49

本文选题：超低温球阀　切入点：压力角　出处：《兰州理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：低温压力容器在社会生活中越来越常见,超低温阀门作为重要的配套设备,在该领域的使用数量也在日益增多。而此类阀门在设计时仍缺乏理论分析和标准依据,且在使用经验较少的情况下,极易出现冷变形及密封泄漏等问题。作为关键设备用的超低温球阀需要通过设计创新和技术研发来解决产品长期依赖于进口和国产化难的技术问题。在低温压力容器领域中,超低温阀门要承受更为苛刻的工作环境。在低温工况下,结构上的温度分布、密封处的热应力及低温下的设计参数是确保阀门正常使用的必要条件。因为巨大温差带来的热变形,使得主密封副的性能降低,因而必须改善阀门的设计参数,以弥补温度场所引起的密封不足,避免引发泄漏。超低温金属球阀的主密封副性能是涉及生产制造、操作使用的核心要素。本文以LNG用超低温固定球阀为研究对象(包括结构参数、温度变化和深冷处理等),对主密封结构进行参数化研究。推导理想光滑接触面的密封比压计算公式;基于传热学理论和沸腾换热原理,通过总结前人的经验公式和实验结果,联立求解出奥氏体不锈钢在液氮中瞬态对流换热系数。采用有限元分析手段建立主密封结构的有限元分析模型,结合数值模拟的方法对超低温球阀在低温下传热和密封问题进行研究,获得阀座密封面上的密封比压分布规律,确定影响阀座密封特性的主要设计参数(包括温度、压力角)。模拟深冷处理工艺,研究温度场瞬态温度变化,探索密封面上的热力耦合作用效果、对比分析密封比压的分布规律,对主密封结构的设计和实际使用提出指导性建议。
[Abstract]:Cryogenic pressure vessels are becoming more and more common in social life. As an important auxiliary equipment, the use of ultra-low temperature valves in this field is also increasing day by day. However, there is still a lack of theoretical analysis and standard basis for the design of these valves. And with less experience, Cold deformation and sealing leakage are easy to occur. As a key equipment, ultra-low temperature ball valves need to solve the technical problems of long-term dependence on imports and localization of products through design innovation and technology development. In the field of cryogenic pressure vessels, The ultra-low temperature valve has to withstand more severe working conditions. At low temperature conditions, the temperature distribution on the structure, The thermal stress in the seal and the design parameters at low temperature are necessary to ensure the normal use of the valve. Because of the thermal deformation caused by the huge temperature difference, the performance of the main sealing pair is reduced, and the design parameters of the valve must be improved. In order to make up for the lack of sealing caused by temperature and avoid leakage. The performance of the main sealing pair of the ultra-low temperature metal ball valve is related to production and manufacture. The core elements of operation. In this paper, the ultra-low temperature fixed ball valve used in LNG (including structural parameters) is taken as the research object. The parameterized study of the main seal structure is carried out by temperature variation and cryogenic treatment. The formula for calculating the seal specific pressure of the ideal smooth contact surface is derived. Based on the theory of heat transfer and boiling heat transfer, the previous empirical formulas and experimental results are summarized. The transient convection heat transfer coefficient of austenitic stainless steel in liquid nitrogen was solved simultaneously. The finite element analysis model of the main sealing structure was established by finite element analysis. Combined with numerical simulation method, the heat transfer and sealing problems of ultra-low temperature ball valve at low temperature are studied. The specific pressure distribution on the seat seal surface is obtained, and the main design parameters (including temperature) that affect the sealing characteristics of the valve seat are determined. By simulating the cryogenic treatment process, the transient temperature change of temperature field is studied, the effect of thermal coupling on sealing surface is explored, the distribution law of seal specific pressure is compared and analyzed, and some guiding suggestions are put forward for the design and practical application of main seal structure.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH134

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