低温压力容器缺陷红外检测及热激励影响分析

发布时间：2018-04-01 18:29

本文选题：低温压力容器　切入点：缺陷　出处：《东北石油大学》2012年硕士论文

【摘要】：低温压力容器是压力容器的常见形式之一，广泛应用于油田、天然气生产过程和石油化工等工艺装置中。低温压力容器盛装着易燃、易爆、剧毒或腐蚀介质，是涉及生命安全、危险性较大的承压设备，在使用过程中常因介质、载荷、温度和环境等因素的影响而产生腐蚀、冲蚀、磨损、应力腐蚀开裂、疲劳开裂、材料劣化等缺陷。因此，，快速诊断低温压力容器使用过程中的缺陷，及时维修设备，是确保设备和人员安全的关键因素。本文根据红外成像无损检测原理、传热学理论，建立了不考虑容器内相变的缺陷传热模型，基于控制体积法，进行不同热激励强度、不同热激励时间、不同环境因素、不同缺陷参数条件下的数值模拟分析，在此基础上根据相变传热的基本理论，建立了考虑容器内相变的缺陷传热模型，利用FLUENT中的多相流模型混合（mixture）模型，对热激励作用下容器内流体的汽化过程进行了模拟，并研究了流体发生相变时对压力容器壁表面温度的影响。研究结果表明：（1）随着热激励强度的增大，压力容器表面的对比温度逐渐增大；（2）随着激励时间增加，最大对比温度呈现先升后降的趋势，最终减小在稳定状态时对应的对比温度；（3）环境因素中风速、表面黑度对红外检测精度的影响较大，而在大气环境中进行压力容器缺陷红外检测时可以忽略环境温度的影响；（4）随着缺陷的增大，压力容器表面对比温度逐渐增大，亦即压力容器内的缺陷面积越大，越容易被检测出来。随着缺陷深度的增加，压力容器表面的最大对比温度是逐渐减小的，也就是说缺陷距离加热表面的深度越浅，表面温度异常越明显，越容易检测；（5）容器内流体在t=10s时发生相变，随着热激励时间的增加气相所占的体积分数增大；当容器内流体发生相变时，对红外检测有一定的影响。本文的研究结论对于指导红外成像技术快速诊断低温压力容器使用过程中的缺陷具有一定的借鉴作用。
[Abstract]:Low temperature pressure vessel is one of the common forms of pressure vessel, which is widely used in oil field, natural gas production process and petrochemical process. Low temperature pressure vessel is filled with flammable, explosive, highly toxic or corrosive medium, which involves life safety. In the process of use, the high risk pressure equipment often produces the defects such as corrosion, erosion, wear, stress corrosion cracking, fatigue cracking, material deterioration and so on due to the influence of medium, load, temperature and environment. Rapid diagnosis of defects in the use of cryogenic pressure vessels and timely maintenance of equipment are the key factors to ensure the safety of equipment and personnel. According to the principle of infrared imaging nondestructive testing and the theory of heat transfer, a defect heat transfer model without considering the phase change in the vessel is established in this paper. Based on the control volume method, different thermal excitation intensity, different thermal excitation time and different environmental factors are carried out. Based on the basic theory of phase change heat transfer, a defect heat transfer model considering phase change in a vessel is established based on the numerical simulation analysis under different defect parameters. The model is mixed by using the multiphase flow model in FLUENT. The vaporization process of the fluid in the vessel under thermal excitation is simulated, and the influence of the fluid phase transition on the wall surface temperature of the pressure vessel is studied. The results show that the temperature of the wall surface increases with the increase of the thermal excitation intensity. The contrast temperature on the surface of the pressure vessel increases gradually with the increase of the excitation time, and the maximum contrast temperature increases first and then decreases, and finally decreases the wind speed in the environmental factors corresponding to the contrast temperature in the stable state. The surface blackness has a great influence on the infrared detection accuracy. However, the influence of ambient temperature on infrared detection of defects of pressure vessels can be ignored in the atmospheric environment.) with the increase of defects, the surface contrast temperature of pressure vessels increases gradually. In other words, the larger the defect area in the pressure vessel, the easier it is to be detected. As the depth of the defect increases, the maximum contrast temperature on the surface of the pressure vessel decreases gradually, which means that the deeper the defect is from the heated surface, the lighter the defect is. The more obvious the surface temperature anomaly is, the easier it is to detect the phase transition of the fluid in the container at 10 s, and the volume fraction of the gas phase increases with the increase of the thermal excitation time, and the phase transition in the vessel will have a certain effect on the infrared detection. The conclusion of this paper is useful for guiding infrared imaging technology to quickly diagnose defects in cryogenic pressure vessels.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TG115.28;TH49

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