低温阀门阀盖颈部温度场分析与结构设计

发布时间：2018-01-14 17:01

本文关键词：低温阀门阀盖颈部温度场分析与结构设计　出处：《兰州理工大学》2012年硕士论文　论文类型：学位论文

【摘要】：随着我国工业的大力发展，石油化工、空气分离、天然气、制冷和低温工程的生产规模也不断发展壮大，对低温阀门的要求也越来越高。低温工程的实践告诉我们，低温阀门质量的优劣直接影响着整个低温工程的进展，实践的教训是很多的，往往因为一个阀门不密封、关不严或打不开，导致了试验的失败或者一次事故，造成大量的人力、物力、财力的浪费，从而影响我国低温工程的发展。低温阀门的用途和普通工业管道阀门的用途基本上没有什么区别，也是用来直接切断或调节低温液体。低温阀门是一种在温度等于或者低于120K的介质中工作的阀门，这种温度的工作介质对阀门构件的影响可能是持续的，也可能是短时间的。除了在低温介质下工作外，同样应当考虑到低温阀门还要在周围环境温度下工作，即在295K左右的温度下工作，在设计阀门元件时，必须要考虑低温介质温度和周围环境温度的共同影响。在低温装置中，阀门的工作条件要比普通工业阀门恶劣得多。由于温度变化范围很大，使阀门的密封十分困难，因而必须要提高阀门的密封效果防止发生泄漏。填料函的密封性是低温阀门设计的关键，采用长颈阀盖结构，其目的就是起到保护填料函的功能，若该处有泄漏将降低保冷效果，导致液体气化，这是在低温状态下随着温度的降低，填料的弹性逐渐消失，防漏性能随之下降。由于介质渗漏造成填料与阀杆处结冰，影响阀杆正常操作，同时也会因阀杆上下移动而将填料划伤，引起严重泄漏。所以低温阀门必须采用长颈阀盖结构形式，此外，长颈阀盖结构还便于缠绕保冷材料，防止冷能损失。本文以工程中的低温承插焊截止阀为例，对低温阀门长颈阀盖结构进行合理的物理模型简化，建立阀盖颈部长度与温度场关系的数学模型。以传热学为理论依据，，采用分离变量法求出长颈阀盖温度场的分布，并以此为依据推导出阀盖颈部长度与温度场的关系式，得到阀盖的最小长度，并且满足阀门设计标准。课题采用ANSYS有限元分析软件作为建模和分析平台对通径DN25的低温承插焊截止阀进行热力分析，从而判定所设计的阀门阀盖长度是否合理，为工程设计提供理论参考依据。
[Abstract]:With the vigorous development of China's oil industry, chemical industry, air separation, natural gas, refrigeration and cryogenic engineering production scale is also growing, the valve on the low temperature requirements are increasingly high. The practice of cryogenic engineering tells us that the low temperature valve directly affect the quality of the progress of the entire Cryogenic Engineering practice lesson many, often because of a valve is not sealed, closed or not open lax, resulting in the failure of the experiment or an accident, causing a lot of manpower, material resources, waste of resources, thus affecting the cryogenic engineering development of our country.
The use of cryogenic valves and industrial pipeline valve basically does not have what difference, is used to cut or adjust the cryogenic liquid. The low temperature valves work in a temperature equal to or less than 120K in the medium of the valve, the working medium of the temperature effect could be sustained on the valve structure, may also be short time. In addition to work in a low temperature medium, also should take into account the cryogenic valve to work at ambient temperature, which work at about 295K temperature, in the design of valve components, must consider the low temperature medium temperature and ambient temperature influence.
In the low-temperature device, the valve's working conditions than ordinary industrial valves much worse. Due to a wide range of temperature, the valve sealing is very difficult, so we must improve the sealing effect of the valve to prevent leakage. The stuffing box sealing is the key to the design of cryogenic valves, valve cover structure with long neck, its purpose is to protect the stuffing, where leakage will reduce the cold effect, causing the liquid gasification, which is under the condition of low temperature with the decrease of temperature, the elastic filler gradually disappear, leak proof performance decreased. Because of the medium valve stem packing leakage caused by ice, affecting the normal operation of the valve stem, but also because the valve stem moves up and down the filler scratches, causing serious leaks. So cryogenic valves must take the long necked valve cover structure, in addition, long necked valve cover structure is easy to wind cold insulation material, prevent cold energy loss Lost.
In this paper the low-temperature socket welding valve for example, low temperature valve on the long necked bonnet to simplify the structure reasonable physical model, a mathematical model of the valve cover neck length and temperature field relationship. Based on the heat transfer theory, the variable separation method is used to calculate the temperature distribution of the long necked valve field, and then according to the relation derived from the valve cover the neck length and temperature field, get the minimum length of the valve cover and the valve to meet the design standards. Research using ANSYS finite element analysis software for modeling and analyzing platform of diameter DN25 low temperature cut-off valve socket welding thermal analysis, to determine the valve cover design length whether it is reasonable, in order to provide theoretical basis for engineering design.

【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH134

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