Study on the dynamic response of polyurea coated steel tank subjected to blast loadings

Steel tanks are widely used in the storage of various chemical liquids, and the blast resistance of the tanks is very important because of the explosiveness of these liquids. To explore a feasible method to improve the blast resistance of steel tanks, the effect of polyurea coating on the blast resistance of steel storage tank is investigated in this paper. The responses of monolithic steel tanks and polyurea coated tanks under blast loads are studied by field blast experiments using TNT explosive, and the results shows that the polyurea layers are effective in reducing the maximum and residual displacements of the tank. Numerical simulations are performed and validated, and the deformation process and stress and strain distribution of the tanks are analyzed accordingly. The increase on the bending moment of the plastic hinge lines of the tanks and the increase of the area density of the cylindrical shell induced by the polyurea layers are believed to be the two main factors contributing to the displacement reduction effect of polyurea in this paper. The validated numerical model is used to study the influence of polyurea layer's thickness on the deflection of the tank, and a nearly inversely proportional relationship between the thickness and the maximum displacement is found. Three deformation modes of the tanks are identified when subjected to blast load with varying intensity and it is found that the displacement reduction effect of polyurea varies in different deformation modes.     

Heat transfer and burning behavior of ADP/MPP epoxy intumescent coatings

Thermal protection of chemical storage tanks is very important when a fire accident occurs. Intumescent coating on the surface of the tank is one of efficient measures to prevent fire. It is essential to investigate the interaction between heat transfer and burning behavior of intumescent coating, which will affect the fire-proof performance of the coating. In this paper, ADP/MPP epoxy intumescent coatings were prepared by adding the intumescent flame retardants aluminum diethylphosphinate (ADP) and melamine phenyl phosphonate (MPP) into epoxy resin (EP). The heat transfer process and burning behavior were analyzed by temperature distribution, thermogravimetric analysis (TGA), cone calorimeter and scanning electron microscopy (SEM). The results showed that the ratio of ADP and MPP, the intumescent characteristics and the structure of the char layer can affect the heat transfer of the coating remarkably. The residual char morphology analysis shows that the coating containing ADP and MPP is more capable of forming a well-structured char layer structure and shows a good thermal insulation performance.     

拱顶储罐气相层惰化过程数值模拟及工艺参数研究

针对油罐在检测、维修前须先将气相层可燃气体用氮气惰化到安全浓度,现场凭经验操作效率低且难以掌握氮气合理用量,容易造成氮气浪费或达不到安全浓度引发事故的问题,为确保惰化过程的安全经济,以常见拱顶储罐为例,首先利用改进后的公式法得出多组分可燃气体惰化效果评价指标;然后根据所得指标采用仿真对储罐气相层惰化过程进行数值模拟,并验证了仿真结果的正确性;最后采用仿真计算方法开展储罐气相层氮气惰化工艺参数的影响研究。研究结果表明:惰化效率与进口压力无关,只随进口流速变化,且大于1 m/s流速后,惰化效率已显著变化,此时可以增加进口管道数量,进一步提高惰化效率。理论研究结果可为现场实施提供参考和指导。     

某储罐区火灾多米诺效应场景推演

化工园区中危险源众多,一旦发生事故很容易在整个园区内蔓延和发展.针对化工园区内储罐密集,容易引发连锁反应导致事故扩大的特点,利用FDS软件对储罐火灾场景进行数值模拟,根据储罐所受热辐射确定化工园区内储罐火灾最可能的事故发生序列,并引入基于设备失效前时间的机械设备故障概率模型对罐区内单个储罐的火灾风险进行研究,得到储罐区...     

A failure analysis of fillet joint cracking in an oil storage tank

This paper has studied failure of an oil storage tank. During operation, several cracks were observed at the fillet weldment between reactor shell and annular plates in the bottom of oil storage tank. Extreme stresses in the structure during its operation were determined taking into account shape and geometry imperfections as well as corrosion influence. Both reactor shell and annular plates are made of carbon steel (SM53C). In this study, in order to identify the causes for the fillet weldment cracking, failure analysis such as fractography, tensile test, hardness test, corrosion test(SSRT), chemical analysis was performed. The failure of oil storage tank is the result of the combined and synergistic interaction of mechanical stress and corrosion reactions. Although cracks were initiated by corrosion, failure was generated by propagation of crack caused by stresses concentration. It was recommended that (1) the local stresses be reduced by improved weld toe geometry, and (2) the reinforcement be used in order to avoid failure by stresses concentration.     

环氧丙烷储罐空气泡沫灭火试验研究

环氧丙烷为低沸点水溶性可燃液体,由于其饱和蒸汽压大,灭火困难,此前,国内外未对环氧丙烷进行过大型工程应用灭火试验研究。为研究空气泡沫对环氧丙烷储罐的灭火性能,分别对环氧丙烷进行了0．25m^2油盘探索性试验、1．73m^2油盘泡沫灭火剂选型试验和直径3．5m储罐工程应用灭火试验。试验结果表明,空气泡沫难以扑灭环氧丙烷储罐火灾,在直径3．5m储罐上,虽然采用了灭火性能较好的泡沫液,且使用了较大的供给强度和较长的供给时问,但仍难灭火。在试验基础上,对环氧丙烷储罐的消防要求提出了建议。     

铁路沿线可燃重气储罐最小隔离区域划分探讨*

为保护铁路线,以某化工厂距离高铁路线最近的丙烯球罐为例,提出丙烯球罐泄漏最小隔离区域划分方法以及2种保护高铁线路方案,利用重气扩散模型和定量风险评价（QRA）软件分别进行丙烯扩散模拟、爆炸模拟,并进行危险与可操作性分析（HAZOP）和保护层分析（LOPA）。结果表明:球罐发生泄漏及火灾爆炸等事故,会给附近铁路线带来严重破坏;丙烯泄漏或球罐因周围其他设备设施或可燃物质着火而温度升高时,保护措施不足;隧道的安全可靠性要高于仅设1道防爆墙,隧道长度需覆盖最小隔离区域的可及范围,在扩散区域内也需设立普通挡墙,在极度危险情况下,需要实施高铁停开等保护措施。     

Numerical analysis on the hot spot in reactive chemical storage

In an exothermic reactive chemical storage tank, a thermal explosion can occur when the heat generation within the storage tank is greater than the heat removal from the storage tank. In a solid system, the existence of an inflection point in the temperature versus time curve is often used as a criterion for thermal explosion. In this study the applicability of this criterion to fluid storage is examined by investigating the hot spot in the system. Transient natural convection of an exothermically reactive fluid in a vertical, cylindrical storage tank with isothermal walls is investigated numerically. The axisymmetric 2-D Navier–Stokes equations governing the flow fields are reduced by introducing the stream function–vorticity formulation and solved by the alternating-direction-implicit (ADI) technique. The reactive heat sources are represented by a zeroth-order rate expression with an Arrhenius-type rate constant. It is found that the hot spot is no longer located in the center of the tank due to the buoyancy effect. In a particular range of Rayleigh number and Frank-Kamenetskii number, the hot spot is found to move periodically. A stable steady regime, stable oscillatory regime and thermal explosion regime can be specified based on the dependence of the critical Frank-Kamenetskii number on the Rayleigh number. In the stable oscillatory regime multiple inflections in temperature versus time are found. Therefore, the existing criterion, which defines thermal explosion by the appearance of an inflection in the temperature versus time curve, is no longer applicable in reactive fluid systems. The results of nonconvective systems do, however, provide a preliminary and conservative estimate for thermal explosion of a reactive storage tank.     

化工储罐间距和体积对爆炸碎片多米诺效应概率的影响

化工储罐爆炸后将产生大量碎片,这些抛射碎片一旦击中相邻罐体容易引发多米诺效应。碎片的抛射方位和抛射距离具有很大的随机性,已有研究多采用概率模型来描述碎片抛射的各分过程。通过总结和发展已有的分过程模型,建立了求取多米诺效应的综合概率模型,并基于蒙特卡罗算法编制了模拟软件,可对化工储罐多米诺效应的发生概率进行预测计算。选取若干常用化工球罐为相邻目标储罐进行实例分析,计算结果表明储罐间距和体积是影响多米诺效应发生概率的两个重要影响因素：随着距离的增大,多米诺效应发生概率不断减小;目标储罐体积越大,多米诺效应发生概率将越大。其中,爆炸碎片对目标储罐的击中概率受上述因素的影响程度更大。该文工作对化工储罐区的安全评价具有一定的参考价值。     

深部低渗透强突出煤层群首采下保护层确定和效果考察

软岩保护层在深部低渗透强突出煤层群首采保护层选择中具有潜在的应用前景。在阐述下保护层开采覆岩移动与采场裂隙演化及瓦斯运移关系的基础上,以芦岭矿为工程背景,通过FLAC3D数值试验,研究软岩保护层开采后的卸压效果,并和不同层位的薄煤层开采卸压效果对比分析。结果表明,在采厚相同的情况下,开采10煤保护层相对于软岩保护层,卸压程度弱,保护范围小,保护效果差。软岩保护层开采后,被保护层处于弯曲下沉带的下限范围。受采动影响,有大量的离层裂隙生成。考察期范围内上覆被保护层(8、9煤层)瓦斯抽采率达62.9%,表明软岩保护层开采能够对上覆被保护层(8、9煤层)起到显著的卸压效果。研究结果可为其他矿区保护层开采选择提供参考,丰富国内保护层开采实践。     

基于氢气充放试验及数值模拟的储氢气瓶安全评价

储氢气瓶是新能源汽车的重要储能设备,其可靠性直接关系到汽车的安全性。研究了不同环境温度下,35 MPa铝合金内胆车用储氢III型气瓶在充放气时的最终温度和应力分布情况,并对其安全性进行了评价。借助试验测试平台,在不同温度下进行了实际充放试验。试验过程中无漏气现象,且最终温度符合要求,表明储氢气瓶在试验条件下是安全的。由此,在获得了储氢气瓶充放时热响应规律的基础上,对不同温度下的氢气充放过程进行了数值模拟,得到其应力分布情况。结果表明,储氢气瓶复合层的应力远小于其材料抗拉强度,即内胆和复合层的强度均可视为满足要求。研究结果可为储氢气瓶的试验开展、安全评价、寿命预测提供依据。     

天然气储气罐破坏效应分析

针对城市天然气储气罐的不断兴建与发展趋势的大型化,对于已建和待建储罐区对周围环境的潜在安全性问题,指出运用破坏伤害范围评价法可直观地预测破坏效应。通过对储罐爆炸释放能量的估算,采用模拟比法结合TNT爆炸试验数据计算出距离储气罐不同距离处爆破冲击波超压值,运用超压准则模拟预测出不同规格、储压下储罐爆破破坏伤害严重程度及危及半径范围;采用世界银行推荐的危害关系式,结合伤害破坏等级分析天然气爆炸破坏效应并与爆破效应比较。5000m3储气罐、储压1.20MPa下,储罐爆破和天然气爆炸危及距离分别可达144.0m和247.7m。依据预测结果,可将罐区周围划分不同区域,为实际工程中罐区选址、建设、安全距离确定及安全预案制定提供参考。     

化工储罐区空袭次生灾害危险性评价研究

根据化工储罐区及其遭空袭次生灾害的特点,以空袭次生灾害的影响范围作为危险性评价的标准,对化工储罐区的空袭次生灾害进行危险性评价。指出储罐遭空袭后的3种毁伤方式;给出储罐遭空袭发生的次生灾害及其扩散的形式与后果;阐述了化工储罐区空袭次生灾害的成灾机理;分别提出热辐射伤害、冲击波伤害和有毒有害物质扩散的危险性评价方法。以池火灾为例,建立了池火灾的危险性评价模型;论述了池火灾危险性评价的具体流程,并进行了案例分析,根据计算结果提出了相应的减灾对策。笔者认为,化工储罐区遭空袭后的次生灾害的危险性评价具有现实意义,对于化工园区、石化厂、危化品仓库等突发安全事故产生次生灾害的危险性评价同样具有重要的参考价值。     

基于QRA角度评价LNG储罐类型的选择

为提高LNG储存的安全性,基于QRA(定量风险评价),利用应急危险定位分析软件分别进行了LNG中小型储罐及大型储槽泄漏事故分析和LNG带压储罐充注压力专项对比分析。结果表明:立式圆柱常压储罐应选择高径比接近于1的罐体而压力罐的选择受高径比的影响很小;当对常压储罐高度有要求时,球形罐是比立式圆柱罐更好的选择;在大型LNG储槽中,常压储槽自身压力很大,可以起到抑制BOG(蒸发气体)产生的作用;在饱和状态下,压力罐的充注压力并非越小越好,需进行针对性分析计算,选取最适合的充注与设计压力。掌握LNG储罐事故后果与罐体形状与类型之间的关系可加强并丰富对其储罐类型选择的认识,可较好的为提高其储存安全性提供数据支撑与理论基础。     

基于VR技术的大型储罐火灾爆炸仿真软件设计

为了研究大型储罐事故后果的严重性，针对大型储罐火灾爆炸试验难以实施的情况，以虚拟现实技术为研究手段，重现大型储罐火灾和爆炸事故过程；通过对储罐火灾和爆炸事故进行理论分析，优选出大型储罐火灾爆炸事故后果数学模型；基于某商业原油储备库布置，利用3Ds Max软件对库区进行建模，结合Qt界面编写技术和OSG粒子效果技术进行交互式设计，划分火灾和爆炸2大仿真模块，设计各模块下属基本功能，形成1套基于真实场景的大型储罐火灾爆炸事故后果三维仿真模拟软件。研究结果表明:基于VR技术的大型储罐火灾爆炸仿真软件具有较强的沉浸感和交互性等特点，能够实时仿真大型储罐火灾爆炸事故动态演变过程，降低大型储罐火灾爆炸试验成本，同时为制定事故应急预案和应急处置措施提供科学参考。     

Assessment of the seismic effect of insulation on extra-large cryogenic liquid natural gas storage tanks

Insulation is typically used in extra-large double-walled cryogenic storage tanks that are used to store liquid natural gas (LNG). These vessels have been designed with the assumption that the insulation offers negligible structural resistance that might cause structural damage. Observation of the deformation of the insulation in such tanks leads to concern that the insulation may become sufficiently compacted to cause significant load transfer between the inner and outer tank. The inner tank, though protected from most external events by the outer tank, is only designed to contain the liquid gas. It is therefore much more sensitive to seismic effects. In this investigation, simplified and 3D finite element models are used to simulate the interaction effects of the fluid, inner tank, insulation and outer tank. This paper presents an initial analysis of the potential effects of LNG tank insulation under earthquake conditions and assesses the potential for structural damage by comparison of models that do or do not consider the insulation layer. The data reported and statistically sorted include the overturning moment, the base shear, the tank wall stress, and the wave height in the tank. The results show that the insulation layer has certain influence on seismic design of LNG tanks.     

基于LOPA逻辑的罐区多米诺效应定量风险评估*

为了更好地降低化工企业罐区事故造成多米诺效应的风险,提出1种基于保护层分析（LOPA）的定量风险评估程序。首先,阐述基于保护层分析(LOPA)逻辑的多米诺定量风险评估流程,即引入包括可用性、有效性及3种逻辑门定义及量化的安全屏障定量评估;然后,利用LOPA的分析逻辑将安全屏障融入多米诺定量风险评估框架中;最后,选取2×2 000 m3苯乙烯罐区为对象,识别防火层与喷淋冷却系统2种安全屏障并开展基于LOPA逻辑的罐区多米诺效应定量风险评估,得出安全屏障能有效地降低多米诺事故发生频率及罐区个人风险的结论。研究结果表明:该分析方法可为化工企业开展多米诺效应定量风险评估提供参考。     

原油储罐基础沉降在线监测与安全性研究

为满足我国各地原油储备及周转需要，油田企业建设有大型原油储罐。部分储罐随着服役年数的增加，出现由于储罐地基的不均匀沉降而导致的罐壁变形，进而浮盘不能自由升降的现象。通过对储罐基础实测沉降数据建立储罐有限元模型，由计算结果分析研究基础沉降储罐的结构响应，并提出该储罐的安全运行液位，可为使用年限较久的储罐的安全评估提供一定的指导。     

Simulating on rollover phenomenon in LNG storage tanks and determination of the rollover threshold

Rollover is a potential risk to the safety of LNG storage tanks during the LNG storage process, so study of its prevention method is very important. In this paper, rollover phenomenon in a liquefied natural gas (LNG) storage tank is modeled physically and mathematically. Its evolution is simulated using FLUENT™ software from the breakdown of stratification to the occurrence of rollover. Results show that the evolution consists of three phases: the initial phase where rollover occurs near the side wall of the storage tank; the turbulent phase where rollover transfers to the center of the tank; and the final phase where new layers evolve. Based on these phases, rollovers in 160,000, 30,000, and 5000 m³ LNG storage tanks are simulated at varying initial density differences, and a rollover coefficient is defined to describe rollover intensity. The simulations show that the rollover coefficient initially increases within a small scope and then increases rapidly with the increment of initial density difference. This turning point is chosen to be the rollover threshold, which is regarded as the critical density difference in this study. The critical density differences obtained from the simulation results of the 160,000, 30,000, and 5000 m³ LNG storage tanks are 3, 5, and 7 kg/m³, respectively, which can be used as their rollover criteria to ensure the safety of LNG storage tanks.     

Dynamic responses and damage of storage tanks under the coupling effect of blast wave and fragment impact

Blast wave and fragment are two main types of physical damage effects representing a significant threat to storage tank structures in chemical industrial parks. Compared with the effect of only blast wave or fragment, the coupling effect of them may cause more severe consequences and is worthy of study. A numerical study of the dynamic responses and damage of a vertical storage tank subjected to the coupling effect of blast wave and fragment is conducted based on a typical accident. The simulation results reveal that stress-concentration and rapid increase of the stress exist in the impacted region of the storage tank under the coupling effect, which leads to the structural damage of the tank exhibiting different failure modes. The coupling effect is significantly apparent following a dramatic increase of the plastic strain, and the damage of the storage tank is further aggravated. From the displacement response and energy absorption, the overall damage of the storage tank subjected to the coupling effect is more severe than that caused by blast wave and fragment separately, which also indicates that the coupling effect is an enhanced damage effect. Besides, the contribution of blast wave and fragment to the coupling effect depends on scaled distance. The results of the study help reveal the coupling effect of blast wave and fragment and prevent domino accidents caused by the coupling effect.