An Overview of the Nature of Hydrocarbon Jet Fire Hazards in the Oil and Gas Industry and a Simplified Approach to Assessing the Hazards

High pressure jet fires pose a serious hazard to offshore installations operated by the oil and gas industry as demonstrated by the Piper Alpha incident. Following the Piper Alpha incident a major initiative by the offshore oil and gas industry operators led to the production of Interim Guidance Notes which provided guidance to operators on how to assess jet fire hazards. However, many areas of uncertainty were identified where no data was available. Areas of particular concern identified in the Interim Guidance Notes were two-phase jet fires, the effect of confinement on jet fires and their behaviour with water deluge. Since that time a considerable body of experimental research has been undertaken. Based on this recent data, this paper reassesses jet fire hazards in an offshore environment and provides updated guidance on the hazards they pose, including tabulated data and simple calculation techniques for predicting jet fire hazards.     

两相射流促进细水雾灭火技术发展

压缩气体射流与水射流混合后所产生的气-水两相射流,可获得连续、高速喷射的细水雾,水滴粒径小,穿入火焰的能力强,可沿水平方向射入火焰中,比喷淋方式水雾灭火可节省90%的用水量,缩短了灭火时间,发挥了细水雾的灭火优势,是细水雾灭火技术的最新发展。所制成的便携式、车载式、固定式的两相射流细水雾灭火装置,可扑灭多种类型的火灾,尤其适合用于扑灭有人存在的空间的火灾。以涡喷发动机为喷射动力的气-水两相射流喷射系统,制成了超大功率的喷射雾状水的消防装备,大幅度提高了控制油、气大火火势的能力和灭火效率。气-水两相射流还有稀释、吹散泄漏出的可燃性气体,防止其点燃的功能,适合于在天然气和有毒有害气体泄漏事故抢险救援中使用。将压缩气体和泡沫液按比例混和后喷射的压缩空气泡沫喷射系统,产生了喷射“干泡沫”的消防车,使灭火用水的利用率提高了8倍,被称为是世界最先进的泡沫灭火技术。气-水两相射流促进了灭火技术革命性的发展,新型的气-水两相射流消防装备不断涌现,展示出了广阔的应用前景。     

烃类流体火灾伤害破坏作用定量分析

对烃类流体火灾的伤害破坏作用进行正确的定量分析是开展重大消防目标火灾风险评估工作的基础。针对烃类流体火灾伤害破坏作用定量分析中存在的问题,系统论述烃类流体火灾伤害破坏作用的定量分析方法,分析并讨论火球、池火、喷射火和蒸气云火灾等不同火灾形式的热辐射通量计算模型及其前提条件,对不同热辐射伤害破坏作用准则及伤害概率模型的适用条件和模型基础进行了论述。     

感烟火灾探测器的灵敏度评测

为了在设计火灾探测系统时，提供探测器的选型依据，该文通过火灾探测综合模拟试验平台(FE／DE)，利用四种国家标准火所用燃料生成典型火灾烟气，对光电型与离子型两种常规点式感烟火灾探测器的灵敏度性能进行了评测与比较。结果表明，对于木材热解生成烟气，与离子感烟探测器相比，光电型探测器的输出烟值增加更为急剧。然而对于棉绳阴燃火、聚氨脂塑料火及正庚烷火生成的烟气，离子型比光电型响应更为灵敏，特别是对于后两者明火生成的能够吸收光而减弱光散射的黑烟。最后指出，依据监控场所中可能存在的可燃物种类而选择相应类型的火灾探测器，将提高所设计火灾报警系统的可靠性。     

Experimental and numerical methodology for the analysis of fireproofing materials

In this study, a methodology for the assessment of fireproofing materials performance is presented. The methodology is based on a combined experimental and numerical approach. A modified version of the ASTM E162 standard fire test was used to expose specimens of steel board protected with different types of fireproofing materials to a steady radiation source. The temperature of the steel board was recorded with an infrared camera in order to evaluate the heat up due to the fire and characterize the protective performance. Experimental results were used to validate a simplified mono-dimensional model which allowed simulating more severe conditions and different protection configurations. A specific key performance indicator (KPI) was used for the quantitative assessment of fireproofing effectiveness. Finally, the professional career of Menso Molag, safety pioneer in the framework of hazardous materials transportation, was outlined.     

Flame extension length of inclined hydrogen jet fire impinging on a water curtain

The use of a water curtain system to prevent fire spread has been extensively investigated, but the case of an inclined jet fire inhibited with a water curtain is not involved. A series of experiments were conducted on inclined hydrogen jet fires with various fuel flow rates, nozzle diameters and inclination angles under the influence of a vertical water curtain. This study aims to explore the burning behaviors of inclined jet flames at the impingement area, specifically the flame extension lengths. The experimental results show that an increase in fuel flow rates or nozzle diameter leads to a larger flame extension length. With the increase of flame inclination angle, the flame extension length decreases and the influence of nozzle diameter on the flame extension length is attenuated. A new dimensionless heat release rate is proposed to correlate with the dimensionless flame extension length by incorporating an air entrainment coefficient. The model built in this study can be used to predict the flame extension length of jet flames with different diameters, fuel flows and inclinations under the influence of a water curtain, and is validated by data in the previous study.     

Thermal effects of a sonic jet fire impingement on a pipe

Although the effects of jet fires are often limited to rather short distances, if their flames impinge on a pipe or a vessel collapse can occur in very short times. In such cases, the heat flux on the affected equipment is very high and wall temperature can increase very rapidly. This can happen in parallel pipelines, if a release occurs and impinges on another one. Nevertheless, jet fire impingement has been scarcely studied. In this communication the results obtained from an experimental set-up are presented. Sonic jet fires impinged on a pipe containing stagnant air or water. The temperatures of the flames impinging on it were measured for the worst case (flame front-bright zone), as well as the evolution with time of the pipe wall temperature at different locations. Initial temperature increases up to around twenty °C/s were registered for the air inside, with maximum values of up to 600 °C reached in 2.5 min, and 800 °C in approximately 9 min. In the case of pipe containing water, in the zone of the wall in contact with the liquid the heating rates were much lower, the maximum temperature reached being up to approximately 150 °C. From the temperatures of the jet flames and of the pipe, the heat fluxes reaching the pipe and the corresponding heat transfer coefficients were obtained. The results obtained emphasized that safe distances are essential in pipelines, together with fire proofing and other safety measures.     

火源位置对腔室火流动特性影响的实验研究

腔室火流动特性是影响腔室火灾蔓延与通风状况的重要因素。通过一系列小尺度腔室火实验,研究了火源位置变化对腔室火流动特性的影响。实验结果表明,随着火源沿腔室底部从壁面向开口方向移动,在开口中性面以上,同一高度处压差与流速增大,中性面高度和烟气层高度均降低,并导致开口质量流率增大。与火源强度相比,火源位置变化对烟气层高度的影响更为显著。火源位置对中性面高度及烟气层高度的影响在壁面处及开口处更为显著,腔室中部位置变化的影响相对较小。火源由壁面向开口移动,会造成火焰高度降低和水平伸长量增加。基于实验数据,给出了考虑耦合火源位置的腔室内火焰水平伸长量的表达式。研究结果可为相关场景下的腔室火灾理论模型提供实验结果支撑。     

石灰凝胶阻化剂防灭火技术在高硫矿的应用研究

在分析现有凝胶阻化剂防灭火机理的基础上 ,笔者针对我国高硫煤矿采空区发火特点 ,研制出石灰凝胶阻化剂的配方 ,并对其防灭火机理进行了详细探讨 ,确定了喷洒该种阻化剂的工艺过程及其应注意的问题。根据现场试验的测定数据表明 ,石灰凝胶阻化剂对高硫煤矿的防灭火效果好     

基于虚拟现实技术的喷射火事故三维动态仿真及应用

基于Shell模型的原理和计算方法,把喷射火焰视为近似倒立圆台形,构建了不同风向影响下的喷射火三维模型,运用虚拟现实技术和三维可视化技术对喷射火事故进行模拟与仿真。以Delphi和OpenGL/GLScene为开发工具,实现了喷射火三维模型的程序化与三维场景绘制,同时引入粒子特效系统,实现了喷射火焰燃烧的实时动态仿真,完成了喷射火三维动态可视化软件系统的开发。最后,利用该系统进行实例分析。应用表明:虚拟现实技术与事故后果模拟相结合,使整个系统实现实时性和形象性的统一,虚拟现实技术在化工行业具有广泛应用前景,也为事故后果预测评估提供科学依据。     

庚烷池火多火源燃烧特性的实验研究

多火源燃烧是森林火灾和城市群发性火灾中重要而又特殊的火灾现象,相关研究很少。通过恒定控制液面高度的实验系统,对直径0.1m、0.2m和0.4m的庚烷池火在单个火源、两火源燃烧和三火源线性排列时的火焰高度、火焰体积和燃烧速率等特性进行了实验研究。研究发现,三火源燃烧时中间火源的火焰高度、火焰体积和燃烧速率明显高于两火源燃烧和单火源燃烧,三火源燃烧时边上火源与两火源的燃烧状况难以区分。这些燃烧特性随着火源间距的减小,呈现增大趋势。热量反馈增强和空气卷吸受限这两种火源相互作用机制相互耦合,且随着火源间距的减小而增强,在S/D（S为火源间距,D为油池直径）为2～4时,两种机制强烈竞争,在其他参数范围内热量反馈增强效应占主导作用。研究还发现火焰体积与热释放速率有较好的线性相关关系,单位火焰体积的热释放速率约为1614kW/m3。     

火灾自动探测的复合特定趋势算法

本文提出了二输入信号的复合特定趋势检测算法，它能够根据信号的稳定值识别复合信号位于稳定值上方的正向变化和稳定值下方的负向变化趋势，在趋势判断函数中引入判别门限，有效地克服了随机噪声干扰；在火灾信号确认中使用了“趋势持续”方法，通过标准试验火和不同环境下非火灾信号的模拟测试表明，该算法探测火灾信号及时、可靠且具有极低的误报警率。     

基于风暴识别算法的森林火灾识别

采用风暴识别算法对森林火灾进行了识别。首先根据参数阈值调整后的风暴识别算法,得到二维分量,结合不同云回波与火灾回波的差异,对火灾回波进行识别。根据算法对浙江省温州市三次森林火灾过程进行识别,结果显示:对于三次火灾过程都能够有效识别。对于火灾发生初期和熄灭时,由于回波强度较弱,回波结构松散,与小范围弱回波混合,导致漏识别。当回波中存在小范围地物杂波时,由于其尺度与小面积火灾接近,最终导致误识别。在森林火灾发生时,该算法可以帮助识别发生火灾的位置,为消防人员提供及时可靠的火灾地点及起火时间。     

利用直升飞机进行森林防火的研究——水用于防止落叶被点燃的方法

每年世界上都会发生大量森林火灾.虽然森林火灾对自然环境造成严重破坏,但现有的火灾防治措施仍不足以防止火灾发生.山区大的绿化区常常在强干燥空气条件下由于火蔓延的作用而被毁灭.很多案例中,尽管消防部门直升飞机和一般飞机被投入使用,仍需要花费很长时间来抑制大规模森林火灾.燃烧的木块可以很容易从下风方向的山脊越过山谷,并在强风作用下广为散播.因此,如何阻止由于燃烧木块而引发的快速火蔓延,是非常重要的研究课题.通常,当燃烧木块在新的地点点燃当地可燃物的初期,火势还是相对微弱的,尺寸也很小,因此,有可能可以在火灾早期借助直升飞机或一般飞机来以水攻火.本文的目标,就是研究在燃烧木块到达的下风区利用直升飞机和一般飞机中的水的方法.本文通过实验室实验和计算机模拟研究了阻止火从一个山脊蔓延到另一个下风方向的山脊的有效方法.     

城市火灾中飞火蔓延距离计算方法研究

飞火是城市火灾特别是城市震后火灾的重要蔓延方式之一,它可以使火灾在相距较远的离散可燃物之间进行跳跃式蔓延,从而增加了扑救难度,威胁扑救人员的安全。因此,对飞火蔓延现象的认识和飞火蔓延距离的计算是降低飞火危险性的前提。基于Baum-McCaffrey火焰羽流模型,重点研究在城市火灾羽流中球形飞火颗粒的上升行为和环境风影响...     

Occupant interactions with self-closing fire doors in private dwellings

Prevention measures to reduce deaths and injuries due to domestic fires have included the provision of self-closing fire doors within dwellings. Such an approach however, is reliant on a behavioural response on behalf of the occupier(s). This research examined occupier behaviour in relation to self-closing fire doors. Forty semi-structured interviews were conducted with individuals inhabiting a new home. In all of the properties with self-closing fire doors, the occupants reported interfering with the self-closing mechanism of the doors. A quantitative survey was subsequently undertaken to obtain frequency data. In the majority of dwellings with fire doors occupiers reported propping these open in some way, or removing the self-closing mechanism from the door. The accounts suggest that, for fire doors to be an effective safety measure within dwellings, a greater emphasis needs to be placed on encouraging occupiers to adopt safe practices in relation to fire doors. Alternatively, other measures will need to be found to address the fire risk.     

An experimental study on the burning rate of a continuously released n-heptane spill fire on an open water surface

Spill fires are common during oil product storage and transportation after a loss of containment. Since the burning fuel is moving and the fuel depth is quite shallow, the burning rate in a spill fire is different from that of a pool fire with a static burning zone. Unlike pool fires, which have been studied for decades and have well-established correlations for burning rate, research on spill fires is inadequate. In this paper, continuously released n-heptane spill fire experiments were conducted on open water surfaces with varying fuel discharge rates. The pool diameters were measured, and the spill fire burning rates were estimated based on a dynamic balance between fuel supply and combustion. The burning rates in n-heptane pool fires from the literature were reviewed and compared with the estimated burning rates in spill fires of the same dimension. The spill fire burning rate was found to be close to that in a pool fire during the initial burning phase but lower than that in a bulk burning pool fire and that in a “fuel-level-controlled” pool fire. The distinction between the burning rates of spill fires and pool fires is explained by the heat balance analysis of the fuel layer. A model for the spill fire burning rate was proposed accordingly. The results calculated with the presented model are closer to the measured data than those calculated with pool fire models.     

结构防火在舰船防火设计中的应用

从舰船火灾发生的规律和特点出发,本着“重点在于防”的精神,论述了舰船消防设计的原则和任务,以及舰船结构防火中必须考虑的几个问题。     

西藏森林火灾时空分布规律研究

根据1992～2005年西藏藏族自治区森林火灾统计,分析了森林火灾发生的时间和空间规律.森林火灾的年际间波动较大,2001以来火灾次数呈明显的上升趋势,但主要是火警次数增多.西藏的森林火灾主要发生在春季和冬季,特别是12月～翌年5月,2月和3月份的森林火灾最为严重.从森林火灾的空间分布来看,森林火灾主要发生在藏东南地区,特别是芒康、察隅、林芝和米林等县的森林火灾较多.引起森林火灾的火源主要是由生产用火和生活用火引起的.文中还对西藏森林火灾发生的火环境进行了分析,气候特点和可燃物分布特征决定了西藏的森林防火期为冬春季,火灾多发生在海拔2800 m～3600 m的阳坡针叶林和阔叶林中,以地表火最多,大多火场面积少于10 hm2.根据西藏森林火灾的发生特点,建议今后在防火基础建设、火源管理、可燃物管理、林火预防和扑救等方面加强工作,提高森林防火的能力.