天然气球罐安全及其水冷却系统研究

发布时间：2018-07-28 14:22

【摘要】：天然气球罐与液化石油气球罐同属于承压状态下的压力容器，其内的介质均属于易燃易爆物，在使用过程中一旦发生事故将造成灾难性后果，所以对其做好安全防护非常重要。目前，国内外研究大都从液化石油气球罐在火灾环境中的热响应规律入手，证明水冷却系统对其的必要性，但对它在火灾环境中的力学响应规律研究甚少。关于天然气球罐的相关研究更是未见相关报道，水冷却系统对天然气球罐的必要性则没有得到明确验证，在相关标准与规范中也没有对天然气球罐水冷却保护系统的设置做出明确规定，导致在实际建设中，天然气储配站对球罐水冷却保护系统设置存在差异，或按照液化石油气球罐的相关规定对天然气球罐设置水冷却保护系统，或不设置水冷却系统。本文将利用ANSYS Workbench对10000m3天然气球罐建立三维几何实体模型，并运用间接法对其进行热-应力耦合分析。首先对火灾情况下的天然气球罐进行热分析，得到罐体温度场的分布；然后将热分析结果作为体载荷施加到结构分析中，以计算出罐体的应力强度分布；再通过应力线性化后处理功能，将计算出的应力分为一次局部薄膜应力、一次薄膜加一次弯曲应力和一次加二次应力；并在第三强度理论的基础上通过应力强度评定原则对各类应力进行强度评定，以校核强度是否满足安全要求，从而验证火灾情况下水冷却系统对天然气球罐的必要性。同时，对天然气球罐的实际工作数据进行简单分析，以说明在日晒高温下水冷却系统对球罐的作用。通过分析得出：在火灾环境下，温度越高，，球罐的应力强度越大而屈服强度越低，当应力强度超过许用应力时，球罐就会破裂；所以有必要对球罐及时进行水冷却保护，以达到灭火与降温目的，避免罐内压力还未到达爆破压力前，球罐由于材料强度不够而破裂。在日晒高温情况下，温度的升高或降低并不会对罐内气体压力造成明显的影响，压力始终不会超过球罐的爆破压力，不需要对球罐进行水冷却降温。
[Abstract]:The natural gas spherical tank and the liquefied petroleum gas spherical tank belong to the pressure vessel under the pressure state, the medium in them belongs to the flammable and explosive object, once the accident occurs in the process of using, it will cause the disastrous consequence, so it is very important to do the safety protection to it. At present, most researches at home and abroad begin with the thermal response law of LPG spherical tank in fire environment, which proves the necessity of water cooling system to it, but there is little research on the mechanical response law of LPG spherical tank in fire environment. The related research on natural gas spherical tanks has not been reported, and the necessity of water cooling system for natural gas spherical tanks has not been clearly verified. In the relevant standards and codes, there is no clear stipulation on the setting of water cooling protection system for natural gas spherical tank, which leads to the difference of the installation of water cooling protection system in the natural gas storage and distribution station in the actual construction. Water cooling protection system for natural gas spherical tanks or no water cooling systems are provided according to the relevant regulations of LPG spherical tanks. In this paper, the three-dimensional geometric solid model of 10000m3 gas spherical tank is established by using ANSYS Workbench, and the thermal-stress coupling analysis is carried out by indirect method. Firstly, the thermal analysis of natural gas spherical tank under fire is carried out to obtain the distribution of the temperature field of the tank, and then the thermal analysis result is applied as the body load to the structural analysis to calculate the stress intensity distribution of the tank. Through the post-processing function of stress linearization, the calculated stress can be divided into local stress, one film plus one bending stress and one plus two stress. On the basis of the third strength theory, all kinds of stress intensity are evaluated by the principle of stress intensity evaluation to check whether the strength meets the safety requirements, so as to verify the necessity of launching cooling system for natural gas spherical tank in case of fire. At the same time, the actual working data of natural gas spherical tank are simply analyzed to illustrate the effect of the cooling system in the sun and high temperature water on the spherical tank. It is concluded that in the fire environment, the higher the temperature, the greater the stress intensity of the spherical tank and the lower the yield strength. When the stress intensity exceeds the allowable stress, the spherical tank will break down, so it is necessary to protect the spherical tank by water cooling in time. In order to achieve the purpose of fire extinguishing and cooling, the spherical tank can be broken because of insufficient material strength before the pressure in the tank reaches the blasting pressure. Under the condition of sun and high temperature, the increase or decrease of the temperature will not cause obvious influence on the gas pressure in the tank, and the pressure will never exceed the blasting pressure of the spherical tank, so it is not necessary to cool the spherical tank with water.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TE972;X932

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