球罐内甲烷气体泄漏形成的可燃气云规律研究

基于计算流动动力学(CFD)方法,以Fluent软件为平台,以大连新港某球罐区为研究对象,建立真实尺寸的球罐内可燃气体泄漏扩散数值模拟模型,分析甲烷扩散规律及可燃气云尺度.提出采用可燃气云稳定状态时的水平方向长度Lmax、竖直方向高度Dmax作为尺度的衡量参数,用以评估可燃气云区域的大小.探讨初始压力、泄漏孔径、正风向风速对尺度参数Lmax和Dmax的影响规律,并对比可燃气体种类对尺度参数的影响.结果表明:甲烷以临界状态通过泄漏孔时,初始压力对Lmax和Dmax的影响可以忽略;Lmax和Dmax随泄漏孔径增加而线性增大,但随正风向风速增加而线性减小;相同泄漏扩散条件下,氢气泄漏引起的可燃气云范围最大,甲烷次之,丙烷最小.     

LNG储罐泄漏火灾爆炸事故后果定量分析

分析了目前用于定量预测LNG储罐泄漏火灾爆炸事故后果的三种主要计算模型,并基于ALO-HA软件对LNG储罐泄漏导致的火灾爆炸事故后果进行了定量评估,深入分析了风速、泄漏部位对LNG储罐泄漏事故的影响.结果表明:①在蒸汽云爆炸模型条件下,可燃区域和爆炸冲击波伤害区域随风速的增大先增大后减小,风速为7 m/s时达到最大值;随泄漏点与储罐底部距离的增大而减小;②在池火模型条件下,热辐射伤害区域随风速的增大先增大后减小,风速为10 m/s时达到最大值;随泄漏点与储罐底部距离的增大而减小;风速使该区域向下风向方向偏移,且偏移程度随风速增加而增加;③在沸腾液体扩展蒸气云爆炸模型条件下,风速和泄漏源位置变化对热辐射伤害区域形状和面积定量计算结果没有影响.     

LNG储罐泄漏危险性计算及影响因素分析

针对LNG储罐泄漏气体扩散模拟分析过程中存在计算和分析过程复杂的问题,选取适当的气体扩散模型,对危险气体的扩散进行模拟和分析,绘制蒸汽扩散UFL(爆炸上限)、LFL(爆炸下限)、1/2LFL浓度等值线图,实现蒸汽扩散伤害分区的准确划分,提高了计算速率和精确度。并利用程序模拟分析了风速、地表粗糙度、泄漏速率等因素对LNG泄漏气体扩散影响。研究结果表明,当风速方向和泄漏源泄漏方向相同时,蒸汽扩散距离和危害范围随风速增大呈减小趋势;蒸汽在下风向扩散距离随着地表粗糙度的增大而减小;扩散距离和危害范围随泄漏速率的增大而增大。     

煤气化封闭框架内可燃气与煤尘泄漏事故分析与防治对策

针对煤气化框架内可燃气泄漏事故及其可能造成的严重后果,基于建筑火灾中“性能化”防火设计思路,设定了煤气化框架敞开与封闭设计下火灾场景,结合可燃气体泄漏的浓度分布机理,分析了煤气化框架敞开与封闭设计对易燃混合气浓度影响的机理,提出采取改进通风等综合措施降低火灾爆炸危险性.通过对典型情况下可燃气与煤尘泄漏规律的仿真分析,结果表明,增加通风口密度、适当调整通风强度可以降低泄漏期间的可燃气体聚集浓度,显著降低危险性,提高了煤气化封闭框架内建筑防火安全性.     

工业LNG储罐泄漏扩散数值模拟

针对工业LNG储罐泄漏问题,基于Fluent软件结合UDF修正风速模型,研究不同工况下泄漏发展情况,并对泄露口下风向沿直线距离上的泄漏气体浓度进行分析,得出准确气体扩散浓度范围。研究结果表明,泄漏孔口越接近地面,横向扩散距离越大。相同风速下,泄漏路径上气体浓度具有相似的变化趋势,风速越高泄漏气体沿扩散路径的稀释作用越强。劲风条件下,泄漏下风口直线路径上最高CH4浓度与距离呈现负相关规律。     

天然气净化厂管道泄漏H2S毒害后果影响因素数值分析

为定量评估高含硫天然气开敞空间泄漏过程中风速、风向、泄漏速度、泄漏方向对毒害后果的影响，以天然气净化厂管道泄漏为例，采用正交实验设计方法设计实验场景，基于CFD进行泄漏扩散仿真实验，以吸入剂量、毒害面积、最大毒害面积到达时间、毒害体积、最大毒害体积到达时间作为毒害效应指标，分析不同因素对毒害后果的影响，并提出后果控制建议。研究结果表明:采用CFD方法进行泄漏扩散仿真能够还原泄漏扩散过程；利用正交实验进行影响因素分析可以节省实验资源、获取准确结果；风向和风速对各后果指标均比较敏感，在天然气净化厂建设过程中应着重考虑风的影响。仿真与正交实验结合的方法能够有效评估毒害后果影响因素的敏感性，可为毒害气体泄漏风险防控提供指导。     

泄漏孔高度对液氯槽罐车泄漏后果的影响研究

为研究液氯槽罐车在道路运输过程中,罐体泄漏孔高度对液氯泄漏扩散过程的影响,本文基于计算流体力学软件Fluent,建立不同高度泄漏孔对应的罐体气相、液相空间泄漏的理论模型,计算不同泄漏模型的泄漏量,研究不同风向、风速、泄漏孔径对氯气泄漏扩散过程的影响。结果表明:风向对2种泄漏模式的扩散范围影响不显著;风速较小时,气相空间泄漏的致命范围大于液相泄漏;风速较大时,液相空间泄漏的致命范围远远大于气相空间;同时,两者受风速的影响具有相似点,风速越大泄漏扩散相对稳定后的氯气浓度值越低;气相、液相泄漏模式的致命范围均随泄漏孔径的增大而增大。研究成果可为液氯槽罐车泄漏事故应急救援、应急处置提供依据。     

高速路上LPG罐车泄漏爆炸危险性分析

在泄漏速度为20、30、50 m/s，环境温度为10、20、30、40℃，地面粗糙度为0.55、0.65、0.71 mm的条件下，利用FLUENT软件进行模拟仿真计算。得到LPG罐车发生泄漏时LPG浓度分布情况，结合LPG火灾爆炸极限，分析泄漏扩散所涉及区域内可能爆炸的范围。研究结果表明，泄漏速度越快，云团扩散速率增大，云团扩散范围越广，爆炸危险性区域增大。风速越大，增大了云团扩散速率，泄漏扩散范围增大，爆炸危险性区域减小。地面粗糙度越大，减缓了云团扩散速率，云团扩散范围减小，爆炸危险性区域增大。     

含硫输气管道泄漏扩散多气团叠加计算模型

为研究含硫气输送管道全管径断裂后的失效影响,提出管道泄漏后硫化氢扩散浓度的计算方法。将管道泄漏过程等效为多个瞬时泄漏气团等时间间隔的连续释放,考虑管道压力变化、风速对泄漏气团的质量、喷射高度的影响,基于高斯烟团模型,对泄漏气团扩散过程中变化的气体浓度进行叠加计算,建立任意时刻沿下风向硫化氢体积分数分布的计算方法。根据输气管道泄漏扩散规律,确定大气扩散参数、各气团质量和喷射高度等基本参数,并以含硫体积分数为10%的输气管进行实例计算。结果表明:地面空气中的硫化氢体积分数在管道泄漏后沿下风向先增大后减小,影响范围不断向下风向延伸;且管径、压力越大,硫化氢在地面的影响范围越广。     

不同风速作用下半水煤气泄漏的数值模拟

针对氮肥工业半水煤气泄漏问题,以计算流体力学(CFD)和燃烧爆炸理论为基础,运用FLUENT软件对半水煤气在不同自然风风速作用下的扩散情况进行了模拟分析.通过比较下游半水煤气各组分体积分数来判断半水煤气的危险爆炸范围以及致死浓度区域.结果表明,当风速为0.5 m/s时,泄漏的危险性气体在自身动量和浮力的作用下缓慢扩散,能够达到爆炸极限或者致死浓度的范围均较小;而当风速达到5 m/s时,圆柱绕流产生的漩涡开始脱落,并携带大量有害气体向下游扩散,致使发生爆炸危险性的区域和致死浓度区域均有所扩大;当风速继续增大到10 m/s时,可能发生爆炸的区域和致死浓度区域范围因空气的稀释作用增强而减小.     

原油储罐区可燃气体探测器布置优化方案研究

为有效预警原油储备区储罐气体泄漏,制定气体探测器布置优化方案,以某大型原油站库为例,基于CFD法和FLACS软件模拟原油泄漏及可燃蒸汽云溢散分布,通过分析蒸汽云扩散规律,实现全方位气体探测器优化布置。结果表明:原油储罐区探测器分别布置在区块21-2、6-1、31-1、40-2,且每个罐组总计布置16处;优化设置方案可满足所有泄漏场景下可燃气体探测需求,有效减少探测器配置冗余。可为泄漏事故早期预警提供技术支持。     

Dynamic simulation of hazard analysis of radiations from LNG pool fire

Because of its highly flammable nature, any accidental release of liquefied natural gas (LNG) could possibly pose significant fire hazard. In this study, a computational fluid dynamics (CFD) model was used to analyze this hazard around an existing LNG station. By assuming an LNG pool fire occurring in an impoundment area, dynamic simulations of flame development have been carried out. In order to provide more reliable simulation results, a study was first conducted to determine the mesh independence and suitable time step. The results of CFD simulations were also compared with those using the commonly-used phenomenological model. The simulation results showed that LNG tanks in the neighbor dike area could withstand the received radiant heat flux, and the areas involving human activities, such as security office and public area, were also secure enough for people to escape from the hazards. LNG vaporizers, which are often located close to tank area, could possibly receive relatively higher radiant heat flux. High temperature achieved on vaporizers could cause material failure. CFD calculations have also indicated that increasing the spacing distance or using flowing water curtain could reduce this temperature. It is concluded that CFD method is significantly more effective to account for LNG hazard analysis and provide realistic results for complicated scenarios, thus providing meaningful information for safety consideration.     

Impact of leakage location and downwind storage tank on the gas dispersion in a typical chemical tank storage area

Toxic gas leakage in a tank area can have catastrophic consequences. Storage tank leakage location (particularly for high leakage) and downwind storage tanks potentially influence gas diffusion in tank areas. In this study, we developed a numerical and experimental method to investigate the impact of a high leakage location and downwind storage tank on gas diffusion based on three (1.05H, 0.90H, and 0.77H, H was the tank height, 22m) leakage field experiments on the leeward side of storage tank, which have been not conducted before. The experiments revealed an unexpected phenomenon: the maximum ground concentration first decreased and then increased with increasing leakage height. The simulations illustrated that the differences in micrometeorological conditions caused the maximum ground concentration of gas emitted from the roof to be higher than that emitted from the tank wall near the storage tank height. The downwind storage tank 1) had little influence on the entire diffusion direction but altered the local diffusion pattern; 2) reduced the maximum ground concentration (∼18.7%) and the distance from the emission source (approximately a storage tank diameter); and 3) had strong influences on the concentration, velocity, turbulence, and pressure on the leeward side. The concentration negatively correlated with the velocity, pressure, and turbulence in the middle of the two storage tanks on wind centerline. Our results can improve understanding of gas dispersion in tank areas and provide references for mitigating loss and protecting lives during emergency response processes.     

液化石油气站储罐区火灾爆炸危险性分析与安全措施

选择具体的液化石油气储配站,分析了该站的危险特性、危险产生的途径及可能造成的后果。在没有任何防护措施的情况下,采用蒸气云爆炸和沸腾液体扩展蒸气云爆炸模型,对该站一个50m3储罐发生泄漏造成的火灾爆炸事故后果进行预测,得出火灾爆炸后的安全距离为大于211．0m。在储配站不能满足此安全距离的基础之上,从防止产生爆炸性气体环境、消除点火源和抑制事故扩大三方面来提出有效的安全措施,降低事故发生的概率及事故造成的损失。其中,站址选在全年最小频率风向的上风侧且周围空旷的地区,罐上设置液位计、压力表、温度计及可燃气体报警器可防止产生爆炸性气体环境;罐及管道设静电接地,法兰用铜线跨接,站内设警示标志可消除点火源;生产区与辅助区间设置隔离墙,罐区周围设置砖混围堤,罐上设安全阀可抑制火灾爆炸事故扩大。     

轻质油品罐区流淌火灾发展特征和危害研究

为了研究罐区储运过程中发生泄漏导致的流淌火事故,设计并搭建了流淌火燃烧试验平台。采用流淌火燃烧试验平台和CFD数值计算2种方法研究了汽油流淌燃烧特性,对比分析表明,流淌火实体试验与CFD数值计算的结果误差在可接受范围内。基于上述结论,以防火堤内储存汽油的4个2 000 m3汽油储罐罐组为研究对象,模拟计算输油管道泄漏至防火堤内引发流淌性火灾的危害特性,得到了流淌火灾蔓延发展过程以及流淌面积、温度场等特征参数的变化规律。研究结果表明:泄漏速率保持不变时,流淌面积逐渐增大直至趋于稳定,其增长速率不断减小;流淌火发展至稳定燃烧阶段时,临近储罐被火焰包围,其中高度为5 m处的罐壁温度和辐射强度最大,温度在1 300 ℃左右波动,辐射强度稳定在500 kW/m2左右。     

工厂三维建模及其事故模拟

利用Microstation软件对某化工厂区进行三维建模,在考虑实际外界风向、风速,不同点火源位置等重要影响因素的条件下,运用计算流体动力学(CFD)软件FLACS,研究了有毒、易燃易爆的氯乙烯液化气体储罐安全阀气体泄漏和储罐底部物料管线液态氯乙烯的泄漏、蒸发、扩散和爆炸作用等过程,计算结果可以给出氯乙烯火灾、爆炸或扩散中毒等事故后果的影响范围和相关精确物理量。模拟结果表明,对于常温下的氯乙烯液化气体球罐,球罐安全阀泄漏后罐区及周边不会有燃烧或爆炸危险;而物料管线在特定的液相泄漏情景下,蒸发扩散的氯乙烯气云则有可能发生气云爆炸;但在弱约束条件下,爆炸冲击波作用比较微弱。该研究方法及其结果可以为石油化工企业选址、设计布局、安全规划、风险分析、应急救援及事故调查等提供更加准确的依据。     

Lithium ion battery energy storage systems (BESS) hazards

There has been an increase in the development and deployment of battery energy storage systems (BESS) in recent years. In particular, BESS using lithium-ion batteries have been prevalent, which is mainly due to their power density, performance, and economical aspects. BESS have been increasingly used in residential, commercial, industrial, and utility applications for peak shaving or grid support. As the number of installed systems is increasing, the industry has also been observing more field failures that resulted in fires and explosions. Lithium-ion batteries contain flammable electrolytes, which can create unique hazards when the battery cell becomes compromised and enters thermal runaway. The initiating event is frequently a short circuit which may be a result of overcharging, overheating, or mechanical abuse. During the exothermic reaction process (i.e., thermal runaway), large amounts of flammable and potentially toxic battery gas will be generated. The released gas largely contains hydrogen, which is highly flammable under a wide range of conditions. This may create an explosive atmosphere in the battery room or storage container. As a result, a number of the recent incidents resulted in significant consequences highlighting the difficulties on how to safely deal with the hazard. This paper identifies fire and explosion hazards that exist in commercial/industrial BESS applications and presents mitigation measures. Common threats, barriers, and consequences are conceptually shown and how they would be identified in a hazard mitigation analysis (HMA). Mitigation measures that can be implemented to reduce the risk of a fire or an explosion are discussed. The presented information is intended to provide practical information to professionals and authorities in this fairly new industry to assure that prevention and mitigation strategies can be effectively implemented and that the regulatory requirement of the HMA can be met.     

氯乙烯储罐安全性分析

氯乙烯是被列入高毒物品的易燃易爆气体物质,液化氯乙烯由于其常温储存下蒸气压力高于大气压而在发生泄漏时容易引起火灾、爆炸、中毒等事故.氯乙烯储罐往往因为储存的物质量大而成为重大危险源.从国内现阶段法律法规、标准要求入手,分析了对氯乙烯储罐的安全要求,并以一具体储罐及其安全设施为实例,研究分析了储罐安全阀发生排放和储罐BLEVE等事故后果.并以此为基础,提出了本实例条件下保证储罐安全的具体要求.     

On the response of 500 gal propane tanks to a 25% engulfing fire

This paper presents detailed data on the thermal response of two 500 gal ASME code propane tanks that were 25% engulfed in a hydrocarbon fire. These tests were done as part of an overall test programme to study thermal protection systems for propane-filled railway tank-cars.

The fire was generated using an array of 25 liquid propane-fuelled burners. This provided a luminous fire that engulfed 25% of the tank surface on one side. The intent of these tests was to model a severe partially engulfing fire situation.

The paper presents data on the tank wall and lading temperatures and tank internal pressure. In the first test the wind reduced the fire heating and resulted in a late failure of the tank at 46 min. This tank failed catastrophically with a powerful boiling liquid expanding vapour explosion (BLEVE). In the other test, the fire heating was very severe and steady and this tank failed very quickly in 8 min as a finite rupture with massive two-phase jet release. The reasons for these different outcomes are discussed. The different failures provide a range of realistic outcomes for the subject tank and fire condition.