Comparison of bursting pressure results of LPG tank using experimental and finite element method

In this study, the resistance of liquefied-petroleum gas (LPG) tanks produced from carbon steel sheet metal of different thicknesses has been investigated by bursting pressure experiments and non-linear Finite Element Method (FEM) method by increasing internal pressure values. The designs of LPG tanks produced from sheet metal to be used at the study have been realized by analytical calculations made taking into consideration of related standards. Bursting pressure tests have been performed that were inclined to decreasing the sheet thickness of LPG tanks used in industry. It has been shown that the LPG tanks can be produced in compliance with the standards when the sheet thickness is lowered from 3 to 2.8mm. The FEM results have displayed close values with the bursting results obtained from the experiments.     

Effect of fire engulfment on thermal response of LPG tanks

A model has been developed to predict the thermal response of liquefied-pressure gases (LPG) tanks under fire, and three-dimensional numerical simulations were carried out on a horizontal LPG tank which was 60% filled. Comparison between numerical predictions and published experimental data shows close agreement. The attention is focused on the influence of different fire conditions (different fire scenarios, various engulfing degrees and flame temperatures) on thermal response of LPG tanks. Potential hazard probabilities under different fire conditions were discussed by analyzing the maximum wall temperature and media energy after the internal pressure rose to the same value. It is found that the less severe fire scenario and lower engulfing case may lead to a greater probability of burst hazard because of the higher maximum wall temperature and media energy before the pressure relief valve (PRV) opens.     

Experimental and analytical investigation of thermal coating effectiveness for 3m(3) LPG tanks engulfed by fire

Two large-scale diesel pool fire engulfment tests were carried out on LPG tanks protected with intumescing materials to test the effectiveness of thermal coatings in the prevention of hot BLEVE accidental scenarios in the road and rail transport of LPG. A specific test protocol was defined to enhance reproducibility of experimental tests. The geometrical characteristics of the test tanks were selected in order to obtain shell stresses similar to those present in full-size road tankers complying to ADR standards. In order to better understand the stress distribution on the vessel and to identify underlying complicating phenomena, a finite element model was also developed to better analyze the experimental data. A non-homogeneous and time-dependent effectiveness of the fire protection given by the intumescing coating was evidenced both by finite element simulations and by the analysis of the coating after the tests. The results of the fire tests pointed out that the coating assured an effective protection of the tanks, consistently increasing the expected time to failure. The data obtained suggest that the introduction of fire protection coatings may be a viable route to improve the safety of the LPG distribution chain.     

Effects of salt concentration on strength and creep behavior of artificially frozen soils

The effects of salt concentration on strength and creep behavior of artificially frozen soils are investigated experimentally. In recent years, considerable interest has developed concerning underground or inground storage of cryogenic liquids. If an LNG storage tank is constructed in the ground with no heating equipment around the tank, the ground will become frozen over the years. To examine the safety of the LNG inground storage tanks, it is necessary to estimate the amount of frost heave involved in such freezing of ground and the frozen-earth pressure acting on the wall of the tank. In this study, the mechanical properties of frozen soils are determined experimentally. These properties are required to analyze the above problems by the finite-element method. Since LNG inground storage tanks are often constructed along the coast, tests were made on frozen soils containing salt.     

大型低温液体贮存站贮罐设计选型论证

分析论证了容积大于 12 5m3 的LNG卫星站贮罐设计选型技术方案 ,评价了A (子母罐 )、B (球罐 )、C (圆筒罐 )、D (常压罐 +输液泵 )、E (集群罐 )方案各自的特点及其适用范围 ,提出了建造大型真空粉末绝热压力罐的模式及用户建站贮罐设计选型时的参考原则     

不同内容物的容器静压及跌落实验结果差异性分析

目的 在相同罐体条件下,分别探究不同内容物的罐体静态压缩及动态跌落实验结果的差异性。方法 针对常见的空气、液体、固体内容物的3类罐体进行静态压缩和动态跌落实验,以跌落方式、跌落高度、测试位置为变量对比分析不同罐体的最大加速度拟合曲线。结果 在静压实验中,空气罐应力集中在下方,液体罐和固体罐应力集中在上方。在跌落实验中,3类罐体的最大加速度值均有差异,差值最大为1.59 km/s2;2种跌落方式下,由上至下,空气罐身应力分布呈三次函数,极值点与对称中心受跌落高度影响较大;液体罐身应力分布呈正弦函数,幅值和初相受跌落高度影响较大;固体罐身应力分布在平跌落与45°角跌落下分别呈指数函数和二次函数,受跌落高度影响不大。结论 内容物不同,容器的静态压缩实验结果不同,动态冲击实验结果有显著差异,跌落方式对容器的动态跌落结果有较大影响。     

Prediction of Pressure Drop at the Entry Section from Top Discharge Blow Tank in a Pneumatic Conveying System

Although some literature can be found on the behavior of blow tanks, very few studies could be found on the pressure loss at the entry section to a pipeline (henceforth called entry pressure loss) from a top discharge blow tank in a pneumatic conveying system, even though its magnitude can be significant as compared to the total system pressure drop. This article presents the results of an experimental study carried out to assess this entry pressure loss. The results indicate that it is possible to scale up the entry pressure loss based on laboratory-scale tests with a reasonable degree of accuracy.     

Incident analysis of Bucheon LPG filling station pool fire and BLEVE

An LPG filling station incident in Korea has been studied. The direct cause of the incident was concluded to be faulty joining of the couplings of the hoses during the butane unloading process from a tank lorry into an underground storage tank. The faulty connection of a hose to the tank lorry resulted in a massive leak of gas followed by catastrophic explosions. The leaking source was verified by calculating the amount of released LPG and by analyzing captured photos recorded by the television news service. Two BLEVEs were also studied.     

边壁周期性不规则国柱形储液罐的动态特性分析

对罐壁具有ｃｏｓ(ｍθ)（ｍ＝１,２,…）型初始不规则的立式圆柱形储液罐的动态特性进 行了理论分析,探讨了初始不规则对储液罐固有频率的影响。借助于速度势函数推导了罐中 的液体动压分布。文中将初始不规则看成是初始位移,采用半解析有限元法处理罐壁,由 Ｈａｍｉｌｔｏｎ原理推导了储液罐的自由振动方程。在该方程中不仅考虑了初始不规则对液体动压 的影响,也考虑了初始不规则所引起的罐壁环向振型间的耦合作用。算例结果表明,边壁初 始不规则对某些固有频率的影响是不容忽视的。     

应用边界元法计算低温液罐的鞍座温度场

利用边界元法计算了液化石油气（ＬＰＧ）船低温液罐鞍座的温度场，首先，对鞍座支撑部分作近似假设，在此基础上进行传热分析并计算鞍座上侧边界温度，然后利用边界元计算了ＬＰＧ船型上低温筒形液罐的鞍座和双叶型液罐的鞍座温度，并对计算结果进行了分析和讨论。     

球罐应力腐蚀开裂研究与安全性分析

对球罐应力腐蚀开裂的原因和主要影响因素进行了分析.针对16MnR和SPV50Q球罐用钢,在分析湿硫化氢环境下应力腐蚀开裂形式的基础上,通过改进的WOL预裂纹试样的应力腐蚀开裂试验,对不同球罐用钢、不同硫化氢浓度、不同焊接状态条件下的应力腐蚀开裂进行了研究,并对设备的安全性能进行了分析,进而提出了防止应力腐蚀开裂的对策.     

Reproducibility of solidification and melting processes in a latent heat thermal storage tank

This study analyzes the reproducibility of solidification and melting tests in a tank containing 181 kg of paraffin for cold storage at around 8 °C. Firstly, an experimental campaign of 10 identical tests was carried out. The performance is practically the same in terms of PCM temperatures and thermal power, with a maximum deviation of 2% in the capacity of all tests. In a second campaign, the impact of the initial conditions was studied. The results indicate that fixing a same mean PCM temperature at the beginning of the tests is insufficient to ensure an accurate reproducibility. Depending on the heat transfer rate during the preparation tests, the capacity differed in up to 33%. In tanks with such quantities of PCM, fixing a uniform initial PCM temperature is hardly possible, thus it is important to prepare the tank with same operation conditions.     

Launch ascent testing of a representative Altair ascent stage methane tank

In order to support long duration cryogenic propellant storage, the NASA is investigating the long duration storage properties of liquid methane. The Methane Lunar Surface Thermal Control (MLSTC) testing is using a tank of the approximate dimensions of the Altair lunar ascent propellant tanks. The tank was insulated with multilayer insulation and placed inside of a vacuum chamber to simulate the various environments that would be encountered during launch and travel from the earth to the lunar surface, including long duration stays on the lunar surface. One of these environments to be studied is the launch and ascent environment; while all the effects of this mission phase cannot be simulated at the same time, an effort was made to simulate as many as possible. Boil-off testing included ambient pressure ground hold testing followed by a rapid depressurization of the vacuum chamber during which the liquid methane tank was allowed to come to steady state condition in the high vacuum environment. The data gathered from the series of tests fit with-in pre-test predictions and yielded much needed test data for rapid depressurization using liquid methane.     

Assessment of an explosive LPG release accident: a case study

In the present paper, an accident occurred during a liquefied petroleum gas (LPG) tank filling activity has been taken into consideration. During the transfer of LPG from the source road tank car to the receiving fixed storage vessel, an accidental release of LPG gave rise to different final consequences ranging from a pool fire, to a fireball and to the catastrophic rupture of the tank with successive explosion of its contents. The sequence of events has been investigated by using some of the consequence calculation models most commonly adopted in risk analysis and accident investigation. On one hand, this allows to better understand the link between the various events of the accident. On the other hand, a comparison between the results of the calculations and the damages actually observed after the accident, allows to check the accuracy of the prediction models and to critically assess their validity. In particular, it was shown that the largest uncertainty is associated with the calculation of the energy involved in the physical expansion of the fluid (both liquid and vapor) after the catastrophic rupture of the tank.     

Ariane 5 attitude control system passivation: theoretical and experimental determination of the explosion threshold pressure

The Attitude Control System (ACS) of the future European heavy launcher Ariane 5 is a Hydrazine system including two bladder tanks pressurised by Nitrogen ; depending on the mission, a residual pressure of some 10 to 20 bars may still remain at the end of the mission. In order to avoid any debris generation, the explosion threshold pressure has been determined theoretically, then demonstrated experimentally. This pressure is defined by the behaviour of the tank under the impact of a micrometeoroid or a space debris : for pressures above it, the tank explodes ; otherwise, it is simply punctured. A theoretical analysis based on fracture mechanics was led first, showing that the crack propagation would become divergent for pressures in the range of 20 to 25 bars. A series of 2D simulations was then performed in two steps : first the local effect of the impacting particle on the tank wall, which enables the computation of the stress fields in the material ; second, the global propagation of such initial conditions in the complete tank. Several cases were computed, with different particles, impacting at different velocities on tanks with different pressures. The worst case was determined and a test prevision was led. The test was performed with a tank pressurized at 18 bar; the impacting particle was 1 mm diameter Aluminium sphere, launched at a velocity of 9 km/s. The tank did not explode, and the resulting hole was close to the one predicted (3.2 mm in diameter, vs. 3 to 3.5 predicted). The resulting maximal residual pressure specified to the ACS is 15 bar, a 20% margin being selected. With this new requirement, we are confident that no explosion can occur in orbit and that the general debris mitigation rules are fully applied.     

Deflated--victims of vacuum

Atmospheric pressure combined with a partial vacuum within chemical plant or refinery tanks can result in some ego-deflating moments. This article will review three catastrophic vessel failures in detail and touch on several other incidents. A 4000-gal acid tank was destroyed by a siphoning action; a well maintained tank truck was destroyed during a routine delivery; and a large, brand new refinery mega-vessel collapsed as the steam within it condensed. Seasoned engineers are aware of the frail nature of tanks and provide safeguards or procedures to limit damages. The purpose of this paper is to ensure this new generation of chemical plant/refinery employees understand the problems of the past and take the necessary precautions to guard against tank damages created by partial vacuum conditions.     

Exposure of a liquefied gas container to an external fire

In liquefied gas, bulk-storage facilities and plants, the separation distances between storage tanks and between a tank and a line of adjoining property that can be built are governed by local regulations and/or codes (e.g. National Fire Protection Association (NFPA) 58, 2004). Separation distance requirements have been in the NFPA 58 Code for over 60 years; however, no scientific foundations (either theoretical or experimental) are available for the specified distances. Even though the liquefied petroleum gas (LPG) industry has operated safely over the years, there is a question as to whether the code-specified distances provide sufficient safety to LPG-storage tanks, when they are exposed to large external fires. A radiation heat-transfer-based model is presented in this paper. The temporal variation of the vapor-wetted tank-wall temperature is calculated when exposed to thermal radiation from an external, non-impinging, large, 30.5 m (100 ft) diameter, highly radiative, hydrocarbon fuel (pool) fire located at a specified distance. Structural steel wall of a pressurized, liquefied gas container (such as the ASME LP-Gas tank) begins to lose its strength, when the wall temperature approaches a critical temperature, 810 K (1000 degrees F). LP-Gas tank walls reaching close to this temperature will be a cause for major concern because of increased potential for tank failure, which could result in catastrophic consequences. Results from the model for exposure of different size ASME (LP-Gas) containers to a hydrocarbon pool fire of 30.5 m (100 ft) in diameter, located with its base edge at the separation distances specified by NFPA 58 [NFPA 58, Liquefied Petroleum Gas Code, Table 6.3.1, 2004 ed., National Fire Protection Association, Quincy, MA, 2004] indicate that the vapor-wetted wall temperature of the containers never reach the critical temperature under common wind conditions (0, 5 and 10 m/s), with the flame tilting towards the tank. This indicates that the separation distances specified in the code are adequate for non-impingement type of fires. The model can be used to test the efficacy of other similar codes and regulations for other materials.     

3850m~3LNG贮罐的设计和制造

介绍3850m3(几何容积)LNG贮罐技术参数及流程特点,根据现有LNG大型贮罐设计制造标准的要求,阐述了3850m3LNG贮罐的结构设计和制造经验。     

水下蛙人主被动探测实验研究

为了对抗来自水下的"非对称"威胁小目标,以携带开放式呼吸器的蛙人作为研究对象,对蛙人的肺部组织、氧气瓶和呼吸产生的气泡的目标强度进行了仿真和实验研究,并测量了不同姿态蛙人的目标强度,分别给出了水池和湖中的测量结果;根据水池和松花湖测量数据,对呼吸声和呼吸器减压阀等辐射源噪声的时频特性进行了分析,并给出了蛙人呼吸声声源级估计的结果。     

Simulation Research of Vaporization and Pressure Variation in a Cryogenic Propellant Tank at the Launch Site

In order to improve depiction of pressure variation and investigate the interrelation among the physical processes in propellant tanks, a 2D axial symmetry Volume-of-Fluid (VOF) CFD model is established to simulate a large-sized liquid propellant tank when the rocket is preparing for launch with propellant loaded at the launch site. The numerical model is considered with propellant free convection, heat transfer between the tank and the external environment, thermal exchange between propellant and inner tank wall surfaces, gas compressibility, and phase change modeled under the assumption of thermodynamic equilibrium. Vaporization rate of the vented LH2 tank and prediction of pressure change in the tank pressurized with GHe are obtained through simulation. We analysis the distributions of phase, temperature, and velocity vectors to reveal interactions among the propellant’s own convection motion, heat transfer and phase change. The results show that the vaporization rate is mainly affected by heat leaks though the tank wall when the tank is vented, but it does not completely accord with the trend of the leakage because of convection motion and temperature nonuniformity of the liquid propellant in the tank. We also find that the main factors on pressure variation in the pressurized tank are the heat transfer on the tank wall surface bonding the ullage and propellant vaporization which has comparatively less influence.