Shake table study of annular baffles in steel storage tanks as sloshing dependent variable dampers

Aboveground steel storage tanks are widely utilized in industrial areas such as oil refineries, petrochemical complexes, oil depots, and etc. Assurance of these infrastructure facilities in high seismic areas is a very important engineering consideration. High amplitude fluid sloshing is one of the widespread causes of steel oil storage tanks during strong earthquakes addressed as an important failure mode. This phenomenon generates additional forces impacting the wall and roof of the tanks. Annular baffles can be used as slosh damping devises to control liquid sloshing within a tank. The main objective of this paper is experimental study of annular baffle effects as anti-sloshing damping devices to reduce fluid wave sloshing height in steel storage tanks typically used in oil and petrochemical complexes during an earthquake. Shake table tests have been used on a reduced scale model steel storage tank in two cases of with and without annular baffles. Three real earthquake ground motion records are used as input base motion. Based on the experimental test results, dynamic characteristics of studied tank models with different filling levels and different baffle dimensions and arrangements have been obtained and summarized in this paper. Also, sloshing heights and convective mode damping values are determined from the test results and compared with API650 code recommendations and recommended equations by other researchers. Generally, the results of this study indicate significant effects of the annular baffles in reducing the fluid wave sloshing height as sloshing dependent variable dampers.     

含硫油品储罐腐蚀产物自燃及其防治理论研究

含硫油品储罐内壁腐蚀产物(Fe2O3、Fe3O4、Fe(OH)3)与H2S反应生成硫化铁,硫化铁的氧化放热是引起储罐火灾的主要原因.实验模拟了油品储罐中硫化铁的生成,研究了在无氧条件下H2S气体与油品储罐内壁腐蚀产物的反应以及生成的硫化铁在自然环境下的氧化自燃性.结果表明,Fe2O3、Fe3O4、Fe(OH)3,以及它们的混合物经硫化后生成的硫化铁具有很高的自然氧化活性,在自然环境中,常温下能迅速和空气中的氧气反应并放出大量的热,热量积聚引起储罐火灾爆炸事故.在实验结论的基础上,提出了一些行之有效的安全防范措施.     

浮顶储罐导电片间隙放电危险性研究

储罐在实际运行中,受浮盘的上下移动、机械应力、老化、油污、金属腐蚀等因素的影响,很难确保导电片与罐壁紧密贴合,容易形成微小间隙,在这种情况下遭受雷击易产生间隙放电,出现打火现象.为了分析导电片与储罐罐壁导电片产生间隙放电的危险性,根据Townsend气体放电理论计算了导电片和储罐罐壁间的击穿电压,采用1.2/50μs冲击电压波开展了导电片间隙放电实验,分析了导电片击穿电压与空气间隙距离的关系.结果证明:当导电片和罐壁贴合不良时,导电片和罐壁之间极易产生火花放电;当空气间隙d=0.1cm时,平均空气击穿电压仅为5280V;随着间隙的增大,空气击穿电压也随之增大;导电片间隙放电实验数据与Townsend气体放电理论值吻合.最后,根据以上结论,针对浮顶储罐导电片间隙放电的危险性,提出了改进措施.     

氯乙烯储罐注水堵漏腐蚀风险的预测方法研究*

为更好地解决氯乙烯储罐注水堵漏可能导致储罐发生腐蚀泄漏的实际问题,提出1种基于ASPEN和神经网络的氯乙烯储罐注水堵漏腐蚀风险的预测方法。运用ASPEN流程模拟软件,对氯乙烯储罐注水堵漏工艺进行模拟,得到不同泄漏孔径下注水速率和HCl浓度的关系;以HCl浓度作为导致腐蚀的主要影响因素,对不同种钢材进行挂片腐蚀实验;结合神经网络分析,得出HCl浓度与腐蚀速率之间的拟合式,预测储罐腐蚀情况。结果表明:神经网络预测结果平均相对误差7.63%,随注水速率的提高,HCl浓度变化呈下降趋势,腐蚀速率变化呈下降趋势;在等效泄漏孔径24 mm、注水速率0.87 m/s时,Q345R腐蚀速率13.93 mm/a,20#腐蚀速率10.48 mm/a,201不锈钢腐蚀速率7.09 mm/a为3者中最低,但此工况下,201不锈钢有点蚀倾向,储罐易发生穿孔,故201不锈钢不宜用作氯乙烯储罐母材,并提出对《石油化工企业设计防火标准(2018年版)》的修订建议。     

烧碱装置降膜蒸发器的腐蚀检查

铢覆层下腐蚀(碱腐蚀和碱应力腐蚀开裂)严重影响烧碱装置降膜蒸发器的安全运行。分析一起降膜蒸发器泄漏案例,发现分离器与管板角焊缝碱应力腐蚀破裂的主要原因是镍覆层焊缝存在贯穿性气孔,认为高浓度碱溶液环境中镍覆层致密性的检查和评价对镍-钢复合板设备安全运行具有重要意义。总结降膜蒸发器管束、管程壳体、焊接接头等部位镍覆层致密性失效导致的腐蚀损伤,提出了重点部位腐蚀检查的技术要求。     

Fragility assessment of bottom plates in above ground storage tanks during flood events

This study aims to improve the fundamental understanding on the performance of bottom plates in above ground storage tanks (ASTs) during flood events. To this end, fragility models that estimate the probability of material yielding and rupture in the bottom plates were derived. A significant number of ASTs are located in coastal areas and are susceptible to hurricane hazards. Consequently, ASTs have suffered severe damage during past hurricanes resulting in spills with catastrophic environmental and social impacts. Therefore, several failure modes such as flotation, buckling, and sliding have been studied in past research. However, the literature lacks studies that consider the failure of bottom plate due to uplift pressure generated during floods and there are no design guidelines to address this issue. To address this gap, fragility functions that provide the probability of failure as a function of tank geometry, material properties, design parameters, and hazard conditions were developed herein. For this purpose, Latin Hypercube Sampling was performed to span the space of these parameters uniformly. For each parameter combination, maximum stresses in bottom plates were determined using analytical formulations for simply supported and clamped boundary conditions and were compared against two different failure thresholds. The results were used to develop a closed form fragility model using step wise logistic regression. Fragility functions were applied to four case study tanks. Sensitivity analysis were performed to understand the impacts of different probability density functions for various variables on the bottom plates’ fragility. The results provided several insights such as ASTs with larger diameter were vulnerable to bottom plate failure. Comparison with other failure modes revealed that the probability of bottom plate failure was higher than flotation failure for anchored ASTs with clamped boundary condition.     

基于改进K-means和CNN的储罐罐底点蚀诊断模型*

为解决储罐罐底点蚀问题,提出基于改进K-means和CNN的储罐罐底点蚀诊断模型,在传统聚类基础上引入肘部法则,保证k值选取3的准确性,将原始声发射信号特征参数和聚类后的类别信息输入模型进行训练,系统预测准确率高达99%。研究结果表明:该模型能够及时发现点蚀现象,指导管理者确定储罐开罐检查时间顺序,避免点蚀穿孔造成的人力、物力损失,降低储罐运行风险,保障储罐运行安全,研究结果可为罐底点蚀诊断提供技术支撑。     

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。     

大型油气(危化品)储罐区安全监控预警系统设计

大型石油、天然气、成品油,易燃易爆,储罐群区危险物质存量大,极易引起灾难性的事故发生。如何在经济高速发展过程中保证安全,是安全生产急需解决的技术难题。本文系统设计面向大型油气(危化品)储罐区安全管理工作的实际需要,兼顾罐区安全管理、实时监控预警及应急救援等多方面的工作,设计一套技术先进、运行成熟、操作简单、扩展性好、容易维护和使用方便的油品储罐区安全监控预警系统,实现大型油气储罐区安全管控一体化,确保大型油气储罐的生产安全和社会安全发展。     

液化气球罐应力腐蚀开裂试验研究

由于炼制进口高硫原油,在炼油球罐检验中发现越来越多的内表面应力腐蚀裂纹。对球罐应力腐蚀开裂的原因和主要影响因素进行分析。从液化石油气球罐的安全性出发,采用线弹性断裂力学方法,针对16MnR和SPV50Q球罐所用钢材,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,对不同球罐所用钢材、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研究,并对设备所采用的材料、所处的介质浓度、材料的热处理状况等进行分析,并提出了防止对策。该方法也适用于液化石油气球罐应力腐蚀开裂,以预测事故的发生。     

长距离输煤管道储浆罐与石油储罐对比研究

对比研究长距离输煤管道储浆罐与石油储罐搅拌设计特点、罐顶设计特点、消防安全设施特点。经分析可知,长距离输煤管道储浆罐宜选用推进式搅拌器,罐壁上设置导流结构,宜采用固定顶、锥顶,设置简单消防安全设施,宜选用难燃保温材料;石油储罐优先选用旋转喷射式搅拌器,罐内油品进行定期搅拌,采用浮顶,大型的一般选用外浮顶,需设置完善消防安全设施。     

Evaluation of the spontaneous combustion tendency of corrosion products in oil tanks based on TOPSIS methodologies

Spontaneous ignition of the corrosion products of an oil tank may lead to an explosion. To evaluate the spontaneous combustion tendency of corrosion products in oil tanks, the thermodynamic characteristic parameters of the corrosion products of oil tanks were obtained by thermogravimetry as evaluation indexes. Then, the objective weights of these indexes were calculated via the CRITIC method, and TOPSIS theory was used to comprehensively evaluate the spontaneous combustion tendency of corrosion product samples from oil tanks. The results show that the weight of the mass loss rate at the ignition point is the highest, and the apparent activation energy of the corrosion products is not the decisive factor affecting their spontaneous combustion tendency. As such, the spontaneous combustion tendency of the corrosion products of oil tanks cannot be based on only the apparent activation energy. The spontaneous combustion tendency of the corrosion products of a gasoline tank is lower than that of a diesel tank. The higher the heating rate is, the stronger the tendency of spontaneous combustion will be.     

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。     

大型原油商业储备油库火灾危险性数值模拟分析

石油储备油库多向大型化、复杂化方向发展,发生事故时扑救非常困难。为了深入探讨巨型油罐火灾发展趋势与规律、事故危害后果,结合宁夏惠安堡原油商业储备油库这一工程实例,采用基于大涡模拟的FDS模型作为模拟计算平台,对巨型油罐火灾的燃烧过程进行数值模拟计算。通过分析计算,得到烟气分布、温度分布、热辐射强度分布等火灾过程参数的变化趋势,以及在有风和无风状态下着火罐对相邻油罐的影响,探讨现行建设工程消防技术标准就储罐防火间距、火灾时对邻近罐体冷却设计要求运用于巨型储油罐时的消防安全状况,为巨型储油罐消防安全科学合理设计提供理论依据。     

储罐液位灾害及其关键液位确定方法研究

储罐关键液位的确定在储罐液位灾害防护系统中起着至关重要的作用,是构建储罐液位灾害防护系统的重要步骤之一。现阶段的储罐灾害分析均偏向于高液位灾害分析,且国内外有关储罐液位的条例规范也较为模糊笼统,仅给出了关键高液位的计算公式与储罐低液位的概念和粗略定值。因此在给出确定响应时间方法的同时,参照API-STD-2350—2012中给出的储罐关键高液位计算公式,结合我国生产实践中储罐运行的实际情况与储罐低液位灾害的具体情况,对原有的3个储罐关键高液位计算公式进行修正,并在其基础上定义了储罐高液位联锁触发液位,给出了该液位与储罐关键低液位的计算公式。     

含硫油品储罐自燃机理及事故原因分析

通过企业现场调研并结合若干事故案例的剖析分析了含S油品储罐自燃事故的发生原因,总结了事故的主要影响因素。在建立含S油品储罐自燃的事故树（FTA）图的基础上,通过最小割集的计算与分析,探讨了事故的主要原因及发生条件,并提出了相应的预防控制措施。     

储罐长周期腐蚀声发射监测试验

对一放置2年时间的储罐试验模型进行长周期的声发射腐蚀监测,通过研究其在稳定腐蚀状态下的声发射信号特征,分析其腐蚀的机理和信号产生的原因,形成对储罐腐蚀更深入的认识。文章还对稳定腐蚀状态下的储罐声发射特征参数进行统计分析,为后续的储罐在线声发射检测评价打下数据基础。     

Risk-based inspection for large-scale crude oil tanks

Periodic Internal Inspection Method often results in under-inspection or over-inspection for large-scale crude oil tank. Therefore, how to determine reasonable internal inspection interval (INTII) has great significance on balancing the safe operation requirement and inspection cost for crude oil tanks. Here, RBI (risk-based inspection) technology is used to quantitatively assess the risk of crude oil tanks in an oil depot in China. The risk comparison between tank shell and bottom shows that the risk of tank depends on the risk of tank bottom. The prediction procedure of INTII for crude oil tanks is also presented. The INTII predicted by RBI method is gradually extended with the increasing of the acceptable risk level. The method to determine the acceptable risk of crude oil tanks is proposed, by which 3.54E+04 are taken as the acceptable risk of the oil depot. The safety factor of 0.8 is proposed to determine the final INTIIs for 18 crude oil tanks. The INTII requirement in China code SY/T 5921, 5-7 years, is very conservative and lower than predicted service life of tanks. The INTIIs predicted by Gumbel method are smaller than by RBI method for tanks with short INTII. Therefore, this paper recommends RBI method to predict the INTII for crude oil tanks.     

Numerical study of dynamic response and failure analysis of spherical storage tanks under external blast loading

The performance of energy infrastructures under extreme loading conditions, especially for blast and impact conditions, is of great importance despite the low probability for such events to occur. Due to catastrophic consequences of structural failure, it is crucial to improve the resistance of energy infrastructures against the impact of blasts. A TNT equivalent method is used to simulate a petroleum gas vapor cloud explosion when analyzing the dynamic responses of a spherical tank under external blast loads. The pressure distribution on the surface of a 1000 m³ spherical storage tank is investigated. The dynamic responses of the tank, such as the distribution of effective stress, structural displacement, failure mode and energy distribution under the blast loads are studied and the simulation results reveal that the reflected pressure on the spherical tank decreases gradually from the equator to the poles of the sphere. However, the effects of the shock wave reflection are not so evident on the pillars. The structural damage of the tank subjected to blast loads included partial pillar failure from bending deformation and significant stress concentration, which can be observed in the joint between the pillar and the bottom of the spherical shell. The main reason for the remarkable deformation and structural damage is because of the initial internal energy that the tank obtained from the blast shock wave. The liquid in the tank absorbs the energy of impact loads and reduces the response at the initial stage of damage after the impact of the blast.     

FeS引发储油罐着火温度动态变化曲线的研究

储油罐着火事故被推测是由硫腐蚀产生的FeS氧化引起的。笔者阐述了储罐中FeS形成的原因 ,并采用自然发火绝热测试系统对FeS自然氧化进行 1 9h的跟踪实验 ,观察FeS绝热氧化过程中温度动态变化特性。实验发现 ,FeS氧化由诱导氧化期、中速氧化期和加速氧化期 3个阶段组成。诱导氧化期是积蓄能量 ,激发FeS活性的过程 ,试样温度基本未发生变化 ;中速氧化期是FeS试样表面的分子活性被激发 ,与FeS试样表面吸附的氧气发生氧化反应的过程 ,温度增加较慢 ;加速氧化期是FeS分子内部的活性被激活并进行氧化反应的过程 ,温度迅速升高。结果证明 :随着反应的进行 ,温度随反应时间变化的幅度越来越大 ,氧化反应的反应热不能及时散开而急剧地积累 ,温度急剧地升高 ,将引起油品自燃。此外 ,通过X衍射图和氧化升温曲线证明 ,水是影响FeS氧化的重要因素。