Experimental study on water sealing of fire barriers and explosion venting of large-scale pipeline with low-concentration gas

Low-concentration gas transported in pipelines may lead to explosion accidents because gas with a concentration of less than 30% is prone to explode. To reduce the incidence of gas explosions, water sealing of fire barriers is implemented, and explosion venting devices are installed along the pipeline. To investigate their suppression effect on low-concentration gas explosion, experiments using methane–air premixed gas under different conditions were implemented on a DN500 pipeline test system. The effects of three types of explosion venting forms (rupture disc, asbestos board, and plastic film) on explosion overpressure and flame were compared and analysed. Results show that the rupture disc, asbestos board, and plastic film can achieve adequate explosion venting, causing the peak decay rates of explosion overpressure to reach 82.37%, 81.72%, and 90.79%, respectively. The foregoing indicates that the greater the static activation pressure of the explosion venting form, the higher the peak explosion overpressure at each measurement point. Moreover, the shorter the explosion flame duration, the greater the flame propagation velocity. The research results provide an essential theoretical foundation for the effective suppression of gas explosion accidents in the process of low-concentration gas transportation.     

基于UHBs的输气管道高后果区泄漏燃爆事故分析

为探究输气管道高后果区中人的不安全行为（Unsafe Human Behaviors,UHBs）对输气管道泄漏燃爆事故发生的影响,结合模糊Bow-tie模型和贝叶斯网络对输气管道泄漏燃爆事故进行分析。构建基于T-S模糊故障树的输气管道泄漏燃爆模糊Bow-tie模型,并转化为贝叶斯网络;从人的不安全行为发生的可能性出发,将不同等级高后果区划分为不同等级人口敏感区;利用专家经验评判法得到不同等级人口敏感区基本事件的先验概率和中间事件的条件概率表;运用贝叶斯网络双向推理算法求解模糊Bow-tie模型。结果表明:随着地区人口敏感等级的提高,输气管道泄漏燃爆事故发生的概率随之增大,发现导致输气管道失效泄漏事故发生的最主要原因为施工破坏,失效原因与EGIG分析的结果基本相符,验证该方法在高后果区输气管道泄漏燃爆事故分析上的可行性,可为输气管道高后果区的安全管理提供决策依据。     

Experimental study on gas explosion and venting process in interconnected vessels

A pilot scale interconnected vessels experiment system was established, and the closed and vented gas explosion characteristics in the system were studied, using 10% methane–air mixture. Regularity of pressure variation in vessels and flame propagation in linked pipes was analyzed. Furthermore, the effects of transmission style, ignition position, pipe length, and initial pressure on explosion severity were discussed. For the closed explosion: explosion in interconnected vessels presents strongly destructive power to secondary vessel, especially transmission from the big vessel to the small one; the worst ignition position is shifting from ignition in the interconnected pipe to the walls of the two vessels; as far as ignition in big vessel is concerned, the peak pressure in secondary vessel increases with the pipe length much faster than that for ignition in small vessel; the peak pressures in two vessels are approximate linear functions of initial pressure. For the vented explosion: the transmission style and interconnected pipe length have significant impacts on the effect of venting on the protection; in order to obtain the better venting effect, the use of a divergent interconnected pipe from the big vessel to the small one in industry is advised and it is necessary to reduce the interconnected pipe length as far as possible or install flame arrester in the interconnected pipe.     

基于SPH-FEM耦合法的含缺陷输气管道爆炸冲击响应研究

针对大口径埋地输气管道发生物理爆炸对并行含体积缺陷邻管的冲击行为,利用LS-DYNA和LS-PREPOST有限元软件建立基于光滑粒子流体动力学-有限单元法的管-土-炸药耦合模型,分析不同缺陷深度、不同缺陷表面积、不同缺陷位置和不同爆心距下邻管的动力响应;基于爆腔预估公式和峰值振速经验公式,验证了所建耦合模型的可靠性,并通过设计算例开展多工况分析。研究结果表明:迎爆面上的缺陷处为动力响应的热点区域,最大响应特征值（应力、位移与振速）位于缺陷中心处,随缺陷深度的增加或管间距的减小特征值增速由平缓到急剧;相比缺陷位置和表面尺寸对管道的扰动程度,缺陷深度和爆心距对管道的动力响应影响较大;在本研究的条件下,建议埋地并行输气管道的安全间距不应小于5.16 m,且腐蚀深度不大于管道壁厚的0.633 6倍。研究结果可为埋地输气管道极端灾害下的风险评估提供技术支撑,为并行管道可能的抗爆隔爆设计提供模拟数据支持。     

抑爆粉剂浓度及粒度对瓦斯爆炸抑制效果的影响

抑爆粉剂的参数指标是影响隔抑爆装置抑制瓦斯爆炸效果的重要因素之一。通过20 L球形爆炸特性实验装置对多种不同抑爆粉剂浓度及粒度条件下的瓦斯爆炸特性参数进行了测试。研究表明:随着抑爆剂浓度的逐渐增加,瓦斯爆炸最大压力降低,最大压力上升速率降低,压力到达峰值时间延迟;在20 L密闭环境,粉剂粒度＜15 μm的条件下,当抑爆粉剂浓度增加到225 g/m3时,瓦斯混合气体被完全惰化,失去爆炸性;在15~80 μm抑爆粉剂粒度范围内,随着粒度的减小,抑爆性能先减弱后增强,在抑爆粉剂浓度为200 g/m3时,15 μm 与70~80 μm粉剂粒度最大爆炸压力分别下降了19.8%,17.8%,而40~50 μm粒度爆炸压力下降了6.4%。     

长径比对管道油气爆炸特性与火焰传播规律影响研究*

为了探究长径比对油气爆炸传播特性与火焰传播规律的影响,为复杂管道受限空间油气爆炸防控提供理论参考,结合油气爆炸与爆炸抑制工程实际需要,构建不同长径比管道油气爆炸模拟实验系统,在此基础上开展不同初始浓度的预混油气-空气混合气爆炸实验。研究结果表明:管道内部的预混油气爆炸超压信号呈先上升后下降的趋势,由于耗散以及憋压效应导致超压下降平稳后仍大于初始压力;同时长径比增加会导致达到最大爆炸超压的油气浓度增加,油气爆炸超压峰值随着长径比的增加呈现上升→下降→上升的规律,小长径比管道的油气爆炸超压峰值高于大长径比管道,但同为小长径比管道或大长径比管道工况的实验结果对比显示爆炸超压峰值随着长径比增加而提升;而超压上升速率则会随着长径比的增加而上升;长径比的增加同时也会促进火焰的加速传播并减小火焰持续时间。     

Dust explosion protection in linked vessels: guidance for containment and venting

Much industrial dust-handling plant consists of vessels connected by pipelines. If a dust explosion propagates through such a system, the overall explosion event can be more violent than if a single vessel only is involved, due to a combination of increased turbulence, pressure piling and a jet flame ignition source in the second vessel. This paper gives guidance, based on an extensive experimental programme reported previously, on two aspects of the protection of interconnected vessels: containment and venting.     

粉碎研磨设备粉尘爆炸的预防

粉碎研磨设备火灾爆炸事故发生率较高。针对该过程的火险特点,防火对策应从防止粉尘沉积,消除粉尘源,防止摩擦、撞击、生热,消除静电危害,搞好工艺防火,惰性介质保护,设置防爆泄压装置,粉尘爆炸的抑制,火灾事故处理措施,加强消防安全教育诸方面加以考虑。     

城区天然气管道泄漏数值模拟与爆炸危害分析

在人口密度为三级和四级的城区内,密集的高建筑物对天然气管道泄漏后的扩散和流场形成产生重要影响。本文以某城市的实际情况为例,建立多建筑物的空间几何模型,采用k-ε湍流方程,SIMPLE算法,模拟了在三种不同风流速度、三种不同压力条件下,城区天然气管道泄漏气体在多建筑物地形中的扩散情况。根据模拟结果,依据天然气的爆炸极限,对模拟结果及其火灾爆炸危害的范围进行了对比分析。结果表明,CH4气体的泄漏扩散同时受管道压力、风流速度和周围建筑物的影响;同时受当地风速的影响,泄漏气柱在风流作用下会发生偏折,造成阻挡风流的建筑物内侧危险气体浓度升高,大大增加建筑物周围环境的危险性。研究结果对城区天然气管道的建设具有一定的指导意义。     

埋地输氢管道泄漏爆炸事故后果模拟分析

为了输氢管道的安全建设与运营,基于计算流体力学FLACS软件,模拟了埋地输氢管道在半受限空间内的泄漏爆炸事故后果,探讨了泄漏孔径、泄漏时长、输氢压力和环境风速对爆炸事故后果的影响规律,并得出相应的危险区域。结果表明:泄漏孔径、输氢压力和最大爆炸超压均与危险区域呈正相关关系,泄漏时长对事故后果几乎无影响;随着输氢压力的增大,危险区域受建筑物和风速的影响更为明显,在建筑物附近形成了狭长的危险区域带;最大爆炸超压和危险区域随环境风速的增大均呈现出先增大后减小的趋势。     

大长径比管道汽油-空气混合气爆炸与抑制实验研究*

为探究狭长受限空间中油气爆炸失控时的发展状态,探索高效环保的油气爆炸抑制方法,利用长径比155的管道开展92号汽油-空气混合气爆炸发展规律和七氟丙烷主动抑爆技术研究。通过测量不同端部开口条件下油气爆炸超压、火焰传播速度、火焰强度等参数,对比研究空爆和抑爆工况下的油气爆炸变化规律,探讨长直管道中的油气爆炸特性,分析七氟丙烷抑爆效果。结果表明:大长径比管道中,端部开口泄爆对降低油气爆炸破坏能力的作用较小,开口与否对最大超压峰值的出现位置有影响;长直管道空爆时,油气爆炸由爆燃发展成爆轰,管道尾部的爆轰波速可达近2 000 m/s;密闭管道中,爆轰发生前火焰传播呈“已燃区-火焰锋面-待燃区-前驱激波-未燃区”的2波3区结构;主动抑爆方式下七氟丙烷抑爆效果良好,最大超压峰值降低幅度可达90%,火焰传播被及时阻断。     

聚烯烃工业粉尘静电爆炸的危险与应对策略

随着我国聚烯烃粉体生产的迅猛发展,粉体生产过程中的静电爆炸事故也相应增多。该文介绍了国外粉尘静电爆炸研究的进展和国内粉尘静电爆炸事故的主要现象。近期国外的研究特点主要是逐渐采用工业规模的实验装置取代实验室的基础研究,着重开展了料仓放电的危险研究和与放电燃爆有关的基础研究,包括安全评价和工业控制条件的推荐研究。国内粉尘静电爆炸事故主要存在的现象有设计缺欠或不合理,装置扩能改造时忽视了脱挥或通风的配套改造,处理不合格料或过渡时应急处理不当,操作失误或不规范,破坏料仓通风控制,料位计选型不当,增加高能放电引燃几率。针对分析出的问题和现象,文章提出了查清运行装置的具体事故隐患,进行防止聚烯烃料仓粉尘静电爆炸的可接受研究和可操作性研究,开展粉尘静电爆炸的危险教育,提高员工的安全意识和应急处理能力等应对策略。     

Development of a mitigation system against hydrogen-air deflagrations in nuclear power plants

A novel mitigation system against hydrogen-air deflagrations in nuclear power plant buildings is proposed and developed through a series of field experiments using explosion vessels of different volume sizes. The mitigation system is installed on the outer surface of the vessels, and it comprises flame arrester and explosion air bag. The flame arrester is made by stacking 10–20 sheets of fine-mesh wire screens, and the air bag is connected for holding explosion gas. The successful mitigation mechanism is the sequence of pressure-rise reduction by the air bag expansion, flame quenching by the flame arrester, and the slow burning of the gas mixture sucked from the air bag back into the vessel due to the negative pressure caused by the rapid condensation of water vapor inside the vessel. Necessary conditions for the successful mitigation system are discussed, and the practical unit size of flame arrester sheet is recommended.     

基于超压值地铁上覆管道爆炸对隧道及人员安全影响研究

为分析地铁上覆管道爆炸对乘客安全影响,采用基于超压冲击波阀值数值模拟,通过将泄漏气体能量等效为TNT当量,分析不同泄漏模式爆炸冲击波对地铁隧道及人员安全影响.结果表明:爆炸产生的超压冲击波对隧道及人员影响小于限值,不会造成人员伤亡,研究结果可为地下工程下穿油气管线安全影响分析提供理论支撑.     

Wire-mesh inhibition of jet fire induced by explosion venting

Explosion venting is widely applied in industrial explosion-proof designs due to the convenient, economical and practical features of this method. Natural gas is usually stored in storage tanks. If the gas in the vessel is mixed with air and encounters an ignition source, explosion venting might occur, producing jet fire, generating new secondary derivative accidents and causing casualties and property losses. In this paper, a set of test platforms including wire-mesh suppression devices is established to study the inhibition of jet fire induced by explosion venting by wire mesh. The experimental research shows that a wire mesh significantly inhibits the jet fire induced by explosion venting. The flame propagation velocity and pressure clearly decrease with increasing numbers of wire-mesh layers. The wire-mesh structure significantly affects the flame propagation, and the more layers of mesh there are, the better the suppression effect is. The flame temperature gradually decreases with the addition of the wire mesh. The mesh size significantly affects the pressure propagation of explosion venting. The explosion pressure gradually decreases with the addition of the wire mesh. With increasing distance between the wire mesh and the explosion vent, the maximum temperature first increases and then decreases, and the maximum explosion pressure first decreases and then increases. In the case of single gas cloud, the flame suppression effect is the most obvious when the wire mesh is 0.2 m away from the explosion vent. In the case of double gas clouds, the flame suppression effect is the most significant when the distance between the wire mesh and the first gas cloud is 0.4 m.     

Development of algorithms for predicting ignition probabilities and explosion frequencies

A project was performed for the Explosion Research Cooperative to develop algorithms for predicting the frequencies of explosions based on a variety of design, operating and environmental conditions. Algorithms were developed for estimating unit-based explosion frequencies, such as those reported in API Recommended Practice 752, but in more detail and covering a much broader range of chemical process types. The project also developed methods for predicting scenario-based explosion frequencies, using frequencies of initiating events and conditional probabilities of immediate ignition and delayed ignition resulting in explosion. The algorithms were based on a combination of published data and expert opinion.     

多分支管道油气爆炸特性大涡模拟

为了研究油库常见的分支结构空间内发生油气爆炸时火焰和压力的传播特性,建立了基于WALE湍流模型及Zimont预混火焰模型的油气爆炸模型;模拟了6种不同分支管道结构空间内汽油/空气混合物爆炸发生发展过程;研究了分支管道数量及相对设置位置对爆炸超压的影响规律,以及分支管道对火焰传播形态和速度的影响规律;模拟结果与前人相关实验规律进行对比。研究结果表明:分支管道对汽油/空气混合气预混爆炸具有明显的强化激励作用;火焰锋面传播经过分支管道时,经历规则—褶皱—规则的变化过程;主管道内火焰传播速度,在分支管道对流场的突扩作用和湍流作用的共同影响下呈震荡变化的规律。     

Numerical simulation and study on the transmission law of flame and pressure wave of pipeline gas explosion

Based on FLUENT simulation software, the laws of transmission of flame and pressure wave in pipeline gas explosion were studied. It turned out that, the maximum pressure value of the explosion point is not the maximum value of the whole explosion process; the maximum pressure value of the pressure wave lowers firstly near the explosion point, then rises to a peak, and then drops gradually; two waves divide the space in the pipeline into three sections during the gas explosion transmission. The result is basically consistent between numerical simulation and experiment, and the conclusion from the simulation provides theoretical basis for research on explosion-proof and suppression devices for underground gas pipeline, as well as for technical regulations of installation.     

化工装置爆炸事故模式及预防研究

对建国以来我国已经发生的典型化工装置爆炸事故原因进行了统计分析 ,总结了爆炸危险性的影响因素。结合对已经发生的事故案例的剖析 ,提取并建立了装置内爆炸事故模式 ,对各种模式的爆炸机理和发生条件进行了初步的研究分析 ,并提出事故的预防措施 ,以期指导安全生产     

圆管状隔爆产品爆炸压力测试实验研究

为了研究隔爆产品内部的爆炸压力,选取了圆管状隔爆产品,设计了隔爆产品爆炸压力测试装置,测试记录了在常温和低温2种环境温度下,乙烯和氢气2种典型可燃性气体在不同内部结构的隔爆产品中的爆炸压力。研究结果表明:相同初始压力条件下,温度越低,气体的爆炸压力越大;在国际标准推荐的试验条件下,低浓度乙烯可以产生与高浓度氢气相同的爆炸压力;隔爆产品结构的变化会导致压力重叠的现象,显著影响爆炸压力的大小。