固定顶储罐弱壁防护结构设计及优化研究

发布时间：2018-06-27 11:33

本文选题：储罐 + 分析设计　；参考：《大连理工大学》2015年硕士论文

【摘要】：近年来我国重大油气储罐安全事故频发,并常伴随着储罐区事故的多米诺效应。为了减小人员和财产损失,工程中通常把储罐设计成弱顶结构。但我国广泛使用的拱顶储罐由于其自限性而不具有足够弱顶保护效果,所以对带弱连接结构的固定顶储罐进行安全性研究及优化设计具有重要意义。本文总结了弱顶储罐的研究现状,针对弱顶结构在定义、设计和保护性三个方面存在的问题,提出一种新的弱连接形式——弱壁结构。设计了不同直径的弱壁储罐用于开展弱壁结构在物理超压及燃爆超压下有效性试验研究,还通过数值模拟技术优化了大尺寸储罐的弱壁设计准则。本文主要内容及结论如下：(1)通过理论分析和计算,提出了弱壁结构。设计了4种不同体积的弱壁储罐,并对焊缝连接强度进行了实验验证。结果表明,焊缝高度越低,焊缝强度越小,越容易实现弱连接。(2)以液压油为介质,开展了DN 1000弱壁储罐在物理超压下的破裂试验。试验中,当罐内压力达到321 kPa时,弱壁处焊缝破裂,罐顶和罐底其余焊缝未破裂,罐底微鼓,罐体发生提离,底部边缘平均提离高度为35.1 mm。弱壁焊缝先于其他焊缝破裂证明弱壁结构能够起到弱连接保护效果。(3)以水为介质,对比开展了DN 3100常规储罐和弱壁储罐的物理超压破裂试验。结果表明,随着罐内压力的增加,储罐底板逐渐拱起,罐体逐渐提离升高。常压储罐在罐内压力升至78kPa时底部大角焊缝破裂,其他焊缝未破裂,罐体底部平均上升高度为175.25 mm。弱壁储罐在罐内压力升至70 kPa时弱壁处焊缝破裂,罐体底部平均上升高度为151.6mm。储罐破裂位置证明,弱壁结构能够起到弱连接保护效果。(4)采用C2H2/Air预混气体,研究了常规储罐(无弱壁无浮盘)、弱壁无浮盘储罐和弱壁浮盘储罐在爆燃超压下的破裂行为。结果表明,常规储罐在罐内爆燃超压达到4.2MPa,但罐体只发生膨胀变形,并未破裂。弱壁无浮盘储罐破裂位置在弱壁焊缝处,破裂压力3.1MPa。弱壁浮盘储罐最先破裂位置在弱壁焊缝处,破裂压力3.5MPa,浮盘的存在对弱壁防护效果无影响,但爆炸压力有所增加。弱壁储罐试验中,弱壁焊缝均先于其他焊缝破裂,说明弱壁结构在爆燃超压下依然能够起到弱连接保护效果。(5)以ANSYS为平台,选择SOLID 185单元模拟罐体及焊缝等连接处,CONTA173与TARGE170接触对单元模拟储罐与地基,并考虑重力的影响,建立了弱壁储罐的三维有限元模型。(6)对比DN 1000弱壁储罐的模拟和试验结果发现：在罐底提离高度方面,两者的误差不到8%,而储罐弱壁焊缝的环向应变方面,平均误差只有6.43%。对比结果证明,模型有足够精度。(7)以验证过的有限元模型为基础,模拟研究了3000 m3储罐上弱壁结构的形式和设置位置对弱壁保护性能的影响。研究发现,弱壁结构能够使应力强度最大值出现在弱壁焊缝处,并增大应力强度的大小,同时还能使该值在危险路径上一次局部薄膜应力加一次弯曲应力的应力强度平均值SⅢ有所增加。(8)大尺寸弱壁储罐优化设计模拟研究结果证明,弱壁结构能改变储罐的应力分布改变,缓解底部焊缝的应力集中。但弱壁结构只有设置在合适的位置,拥有合适的焊角高度时,才能对储罐起到弱连接保护作用。
[Abstract]:In recent years, the safety accidents of major oil and gas storage tanks are frequent in our country and often accompanied by the Domino effect of the tank area accident. In order to reduce the loss of personnel and property, the storage tanks are usually designed to be weak top structures. But the widely used dome storage tanks are not enough to protect the weak top because of their self limitation. The safety research and optimization design of the fixed top storage tank are of great significance. In this paper, the research status of the weak top storage tank is summarized. In view of the problems existing in the definition, design and protection of the weak top structure, a new weak connection form, weak wall structure, is proposed. The weak wall storage tank with different diameters is designed to carry out the weak wall junction. The effectiveness of physical overpressure and explosion overpressure is studied and the weak wall design criteria for large size tanks are optimized by numerical simulation. The main contents and conclusions of this paper are as follows: (1) through theoretical analysis and calculation, the weak wall structure is proposed. 4 kinds of weak wall storage tanks with different volumes are designed, and the strength of weld joint is real. The results show that the lower the weld height, the smaller the strength of the weld, the more easy to realize the weak connection. (2) the fracture test of the DN 1000 weak wall tank under the physical overpressure is carried out with hydraulic oil as the medium. In the test, when the pressure in the tank reaches 321 kPa, the weld seam of the weak wall is broken, the other welds in the tank top and the bottom of the tank are not broken, the bottom of the tank bottom, the tank bottom micro drum, the tank body occur. The average extraction height of the bottom edge is 35.1 mm. weak wall weld. The weak wall structure can play a weak connection protection effect. (3) taking water as the medium, the physical overpressure fracture test of the DN 3100 conventional storage tank and the weak wall tank is compared. The results show that the tank floor is gradually arching with the increase of the pressure in the tank. When the pressure of the tank in the tank rises to 78kPa, the bottom welds of the bottom are broken and the other welds are not broken. The average rising height of the bottom of the tank is 175.25 mm. weak wall storage tank when the inner pressure of the tank rises to 70 kPa, the weak wall weld is broken. The average elevation of the bottom of the tank is proved to be the rupture position of the 151.6mm. storage tank, and the weak wall structure is proved. The effect of weak connection protection can be achieved. (4) using C2H2/Air premixed gas, the fracture behavior of conventional storage tank (without weak wall without floating disc), weak wall without floating disk storage tank and weak wall floating disk tank under overpressure is studied. The results show that the overpressure of the conventional tank is 4.2MPa in the tank, but the tank only has expansion and deformation, and the weak wall is not broken. The weak wall is not floating. The rupture position of the disk storage tank is at the weak wall weld, the rupture pressure of the 3.1MPa. weak wall tank first rupture position is at the weak wall weld, the rupture pressure is 3.5MPa, the existence of the floating disc has no effect on the weak wall protection effect, but the explosion pressure has increased. The weak wall weld test shows that the weak wall weld is preceded by the other weld seam rupture, indicating that the weak wall structure is deflagrated over the excess wall. The weak connection protection effect can still be achieved. (5) taking ANSYS as the platform, selecting SOLID 185 unit to simulate the connection of tank and weld, CONTA173 and TARGE170 contact the unit simulation tank and foundation, and consider the influence of gravity, the three-dimensional finite element model of the weak wall storage tank is established. (6) comparison of the simulation and test knot of the DN 1000 weak wall storage tank It is found that the error of the two is less than 8% in the lift off height of the tank bottom, and the average error of the circumferential strain of the weak wall weld of the tank is only 6.43%. contrast results. (7) based on the verified finite element model, the form and position of the weak wall structure on the 3000 m3 storage tank are simulated and the weak wall protection is studied. The study shows that the weak wall structure can make the maximum stress strength appear at the weak wall weld and increase the stress strength, and can also increase the average stress strength of a local thin film stress plus a bending stress on the dangerous path S III. (8) the optimization design of large size and weak wall storage tank The results show that the weak wall structure can change the change of the stress distribution of the tank and relieve the stress concentration of the bottom weld, but the weak wall structure can protect the tank from the weak connection only when it is set at the right position and has the right angle of the welding angle.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE972

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