高压液氧储罐的高效预冷方法研究

发布时间：2018-03-20 05:36

本文选题：高压液氧储罐　切入点：低温液体　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着低温技术的发展,低温液体的应用日趋广泛。与常规流体相比,低温液体沸点低,汽化潜热小,制取成本高。为了能输送和存储单相低温液体,保证输送管道和低温储罐的安全,预冷过程不可或缺。目前,工程上对预冷过程的控制主要依赖于操作人员,处于经验与半经验状态,缺乏明确的理论指导。为了提高预冷过程经济性,对预冷时间与预冷介质消耗量控制提出了更高的要求。对预冷过程进行进一步研究有助于此类问题的解决。高压液氧储罐筒体较厚,使用过程中对安全性能要求高,预冷方案的制定尤为重要。现有的预冷研究主要针对常压薄壁小管径管路及超大型LNG货舱,对厚壁高压低温储罐的预冷研究鲜有报道。为了能安全、经济、快速地对高压液氧储罐进行预冷,本文主要开展了以下工作:1)从热力学基本理论出发,进行预冷时间及预冷介质消耗量预测。采用稳态与变热导率的热力学分析方法,建立储罐预冷时间与预冷介质消耗量数学模型,推导了储罐温度随时间的变化关系,探讨进口流量与预冷时间、介质消耗量之间的相互影响。并将不同的计算方法相结合,指导选取最佳预冷流量;2)采用CFD模拟方法,模拟储罐在预冷过程中的降温过程。通过相变模型修正与时间步长验证,获得底部进液过程中不同进口流量下储罐的温度、压力、气液分布变化,获得罐内气体及罐壁的冷却规律;3)为了缩短预冷时间及减小预冷过程中罐壁因温差产生的热应力,对储罐结构进行了优化。在罐内增设纵向喷孔,可有效改善罐壁因温差带来的应力集中现象;基于材料低温特性的壁厚设计计算方法,充分利用材料的低温物性,可明显缩短预冷时间。上述研究结果为高压液氧储罐的优化设计提供参考依据。
[Abstract]:With the development of cryogenic technology, cryogenic liquids are more and more widely used. Compared with conventional fluids, cryogenic liquids have lower boiling point, lower latent heat of vaporization and higher production cost. The process of precooling is indispensable to ensure the safety of the pipeline and the cryogenic tank. At present, the control of the precooling process in engineering mainly depends on the operator and is in the state of experience and semi-experience. In order to improve the economy of precooling process, A higher demand is put forward for the control of precooling time and consumption of precooled medium. Further study on the precooling process is helpful to solve this problem. The cylinder of high pressure liquid oxygen storage tank is thicker, and the safety performance is high in the process of operation. It is very important to make the precooling scheme. The existing research on precooling is mainly aimed at the small diameter pipe and the super large LNG cargo tank under atmospheric pressure. The research on the precooling of the thick-walled high-pressure low-temperature storage tank is seldom reported. In order to be safe and economical, the research on the pre-cooling of the high-pressure low-temperature storage tank with thick wall is seldom reported. The precooling of high pressure liquid oxygen storage tank is carried out quickly. The following work is mainly carried out in this paper: (1) based on the basic theory of thermodynamics, the precooling time and the consumption of precooled medium are predicted. The thermodynamic analysis method of steady state and variable thermal conductivity is adopted. A mathematical model of precooling time and consumption of precooled medium is established. The relationship between the temperature of storage tank and time is deduced. The interaction between inlet flow rate, precooling time and medium consumption is discussed, and different calculation methods are combined. Using CFD simulation method to simulate the cooling process of the tank during the precooling process, the temperature and pressure of the tank under different inlet flow rates are obtained through phase transformation model correction and time step verification. In order to shorten the precooling time and reduce the thermal stress caused by temperature difference in the tank wall during precooling, the structure of the tank is optimized. It can effectively improve the stress concentration caused by the temperature difference of the tank wall, and make full use of the low temperature physical property of the material by the design and calculation method of the wall thickness based on the low temperature characteristic of the material. The results can provide reference for the optimization design of high pressure liquid oxygen storage tank.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ116.14

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