水平风对不同液位深度酒精池火火焰长度的影响

通过改变风速、液位深度的大小,研究边界条件变化对酒精池火火焰长度的影响。研究结果表明：在无量纲液位深度小于一定值时,酒精池火的火焰长度会随着风速的增加而增大,当无量纲液位深度较大时,油盘外部酒精池火的火焰长度基本为0。风速相同而液位深度不同时,酒精池火的火焰长度会随着液位深度的增大首先增大,而后逐渐减小。这主要是因为,液位深度较大时,燃料表面的供氧量降低导致燃烧效率降低,最终导致火焰长度的减小。     

Multiple pool fires: Occurrence,simulation, modeling and management

When two or more pool fires burn in such close proximity of one another that they can influence each other, they are termed ‘multiple pool fires’ (MPF). The characteristics and the structure of MPFs are significantly different from that of stand-alone pool fires. Even though MPFs have known to occur fairly often in chemical process industries, much lesser work has been done towards simulation, modeling and control of MPFs as compared to stand-alone pool fires.This paper is perhaps the first-ever attempt at surveying the MPF state-of-the-art. It recounts MPF accidents and catalogs the controlled experiments that have been done to understand the mechanism and impact of MPFs. Attempts to model MPFs have been assessed and possible ways to manage MPFs have been touched upon.     

The effect of barriers on reducing thermal heat fluxes from a hydrocarbon pool fire

The radiant heat flux from a pool fire is frequently calculated using the solid flame model, where the flame envelope is approximated as a stationary cylinder whose surface emits thermal radiation at a constant rate. Radiant heat flux calculations using the solid flame model assume the target to be at a given elevation, typically at ground level, and to have an unobstructed view of the fire. The presence of obstacles (e.g., walls, buildings, etc.) or terrain features that would create shaded areas and provide shielding of a target from the fire is typically neglected in these calculations: this is a conservative approach, but it is not accurate. This paper presents a methodology to utilize the solid flame model to calculate the heat flux to a target while taking into account the presence of an obstruction between the target and the fire. The shielded solid flame method can quantitatively account for the presence of obstacles as a passive mitigation measure and allows project developers or designers to optimize their facility layout to meet safety requirements. The methodology presented in this paper uses the same correlations found in currently used solid flame models (e.g., LNGFIRE3), therefore, it remains consistent with current regulatory requirements for LNG facilities in the U.S.     

Characteristics of large cooking oil pool fires and their extinguishment by water mist

Large cooking oil pool fires, occurring in industrial oil cookers, present a severe hazard to food processing plants due to their size and the large amount of hot oil involved. This paper reports a series of full-scale fire experiments conducted in a large industrial oil cooker mock-up. The characteristics of large cooking oil pool fires and the effect of oil depth and hood position in the oil cooker on fire growth were studied. The use of water mist for extinguishing large oil pool fires and their extinguishing performance under different discharge pressure and with different types of water mist systems were investigated. Experimental results showed that the cooking oil underwent a substantial expansion in volume during heating. The fires developed quickly once the oil auto-ignited. The fire growth rate was affected by the oil depth in the pan and the hood position in the oil cooker. The water mist fire suppression systems effectively extinguished large cooking oil fires and prevented them from re-igniting. Their extinguishing performance was determined by the type of water mist system, discharge pressure and hood position in the oil cooker.     

Improvement in the prediction of gasoline pool fire behaviour: CFD modelling and validation

The development and implementation of mathematical models through Computational Fluid Dynamics (CFD) techniques has been acknowledged as a promising tool for the prediction of hydrocarbon pool fires behaviours. In this sense, different approaches, with different assumptions and simplifications, and accounting for different phenomena, have been developed in the literature. However, the deviations in the predictions of the experimentally determined parameters, such as temperatures profiles, flame heights and radiative heat flux, by the implemented models are still high. Therefore, the implementation of these models to predict combustion phenomena and flame behaviours for various scenarios is limited. In this work, the software C3D is used to model gasoline pool fires of different diameters, and under different wind conditions, in order to improve the quality of the predictions of the flame behaviour. The modelled cases correspond to the experimental studies reported in literature. The results from the implemented model show an improved predictive quality when compared with other modelling works reported on literature for the same experimental cases. The deviations in the time averaged temperature, flame height, surface emissive power and radiative heat flux, has been calculated to be 5.0%, 0.05%, 6.32% and 3.82%, respectively.     

The study of burning behaviors and quantitative risk assessment for 0# diesel oil pool fires

The liquid fuel safety issues on fuel storage, transportation and processing have gained most attention because of the high fire risk. In this paper, some 0# diesel pool fire experiments with different diameters (0.2–1 m) were conducted with initial fuel thicknesses of 2 cm and 4 cm, respectively, to obtain liquid fuel combustion characteristics. Some key parameters including mass burning rate, flame height and the flame radiative heat flux, associated with fire risk, were investigated and determined. Subsequently, a detail quantitative risk assessment framework for 0# diesel pool fire is proposed based on the 0# diesel burning characteristics. In the framework, the probability of personal dead and the facility failure are calculated by the vulnerability models, respectively. In the end, 10 special tank fire scenarios were selected to show the whole risk calculation process. The tank diameter and the distance to pool fires were paid more attention in the cases. The safety distances in the cases are provided for the persons and nearby facilities, respectively. The paper enriches the basic experimental data and the provided framework is useful to the management of 0# diesel tank areas.     

全尺寸巷/隧道火灾风烟流温度预测模型与验证

为探究巷/隧道火灾热动力灾害的演化规律,基于能量守恒定律和热量转换关系,建立巷/隧道火灾风烟流温度演化的预测模型;考虑巷道分叉和汇合对烟气蔓延和温度的影响,构建分叉和汇合巷道内烟流温度随时间变化的演化模型。通过开展全尺寸巷道火灾实验以及与国内典型隧道火灾试验数据对比,对理论模型进行验证。研究结果表明：理论模型所呈现的烟气温度随时间的变化关系,能较好地反映火灾发展的3个阶段,烟气温度的变化趋势符合火灾火源燃烧特性曲线;理论模型能够准确地预测顶棚最大烟气温升以及温度纵向衰减现象,烟气最高温度预测值与实验结果的误差率在15%以内。研究结果可为巷/隧道火灾时期的烟气控制和救援提供理论参考。     

Uncertainty analysis in the nuclear industry: Analytical unavailability modelling incorporating ageing of safety components

There is a growing interest in analyzing the possibility for current nuclear power plants operation extension. In that sense, life management programs, considering safety components ageing, are being developed and employed. On the other side, the large uncertainties of the ageing parameters as well as the uncertainties associated with most of the reliability data collections are widely acknowledged.This paper deals with uncertainty analysis associated with specific ageing rates database. The analysis is conducted using an analytical unavailability model applied for a selected safety system in a nuclear power plant. The most important problem is the immense uncertainty associated to the component ageing data sets as well as the lack of the very data in general, which would correspond to the more detailed modelling of ageing.New probability distributions, encompassing the ageing rates available in the considered data set, are suggested. The obtained results indicate the extent to which the uncertainty of the considered ageing data set, given the inherently assigned probability distribution, influences the performed unavailability calculations. Additionally, comparative analysis regarding the insights gained out of the application of the suggested probability distributions is conducted.     

含二羟基DOPO衍生物阻燃改性环氧树脂的制备与热性能研究

DOPO(9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物)、多聚甲醛、二乙醇胺为原料合成了含二羟基的DOPO衍生物DHDOPO,并作为反应型阻燃剂引入到环氧树脂分子链结构中,制备出一组不同含磷量的阻燃环氧树脂复合材料。采用极限氧指数(LOI)法和垂直燃烧(UL-94)法测试材料的燃烧性能,结果表明,在含磷量为1.5%时,氧指数达到35.0%,并达到V-0级别。锥形量热计(Cone)数据显示阻燃改性后的环氧树脂具有更低的热释放速率峰值(PHRR)和总热释放量(THR),说明具有更高的火灾安全性。此外,还通过热重分析(TGA)实验研究了DHDOPO对环氧树脂热稳定性能的影响。通过扫描电镜对燃烧过后的炭渣形貌进行分析,推测了燃烧的过程和阻燃的机理。     

Experimental investigation on flame and detonation quenching: applicability of static flame arresters

The present investigation was aimed at demonstrating the pertinent use of a flame/detonation arrester for the safety in the process industry. The experimental data provide information on the performance of a static flame arrester. The experiments were conducted in a 3-m long and 28-mm i.d. tube. The arrester, itself consists in 2-mm i.d. tubes arranged in a honeycomb type structure which is located in the middle of the test tube. This is aimed at promoting heat losses during the passage of the flame. The experiments were conducted with fuel-rich mixtures of methane–ethane–ethylene at initial pressures in the range of 0.1–0.6 MPa. These very rich mixtures were more or less diluted in inert, namely, N₂, as well as a mixture of CO₂ and Ar, in order to match with compositions that are currently used in the process industry. The experimental results show that this device is appropriate for flame quenching but, in most cases, detonations were not successfully arrested. These unsuccessful operations of the device occurred for flames at a high velocity, namely for Re numbers of the order of or greater than 15,000.     

矿井热宽温度环境人体热健康分区热调节模型*

为评价矿井热环境中工人职业健康安全状况,提出矿井热宽温度环境人体热健康状态的基本特征与生理要求,分析热宽温度环境人体分区热调节规律与热健康状态的对应关系。基于生物控制论的观点,提出热宽温度范围内不同热应力作用下人体分区热调节机制,建立人体分区热调节模型。结果表明:模型能实现对环境热应力作用下人体物理热平衡状态与生理状态的参数化描述,揭示多因素作用下人体热健康状态的热应力边界与变化规律。分区热调节模型提供了人体热健康状态定量模拟平台,通过参数调整可使模型适应研究需求,模型为井下热环境工人职业健康安全状况分析与评价提供了可参考的思路与方法。     

含DOPO磷酸酯阻燃改性环氧丙烯酸树脂的制备及热性能研究

将工业上广泛应用的光固化树脂EA作为基体,通过分子设计,利用甲苯二异氰酸酯TDI的双异氰酸酯结构将合成的磷酸酯阻燃剂ODOPM链接到其分子主链上,制备出一组改性的光固化丙烯酸酯预聚物。利用FT-IR,1 H-NMR,31P-NMR对分子结构进行表征;极限氧指数（LOI）和微型量热仪（MCC）的结果表明材料的阻燃性能明显提高,改性后树脂的热释放速率峰值PHRR相对于EA降低了近66%,总热释放量也明显降低;扫描电镜结果显示改性后的树脂固化膜形成的炭层变得更平滑和致密,并且完整无破裂现象;同时对固化膜的热稳定性和热降解过程进行了探讨。分析论证了ODOPM改性修饰后的EA有更高的阻燃性,成炭能力明显增强,形成的致密炭层有效地阻止了热交换,使材料在高温下更稳定。     

道化学火灾、爆炸危险指数法在1,3丁二烯聚合安全性评价中的应用

道化学火灾、爆炸危险指数法是在化工领域中广泛应用的一种评价方法,根据该法制定的指数选取规则,可对工艺单元火灾爆炸危险性进行量化和分级.以某化工厂3000t/a三聚体生产项目为背景,从工艺过程、危险物质、安全设施设计等方面,对1,3丁二烯聚合过程火灾、爆炸危险性进行分析;定量评价工艺装置及所含物料潜在危险性,得出主装置区、储罐区固有危险等级,分析不同状态下安全补偿系数对降低危险等级的影响,提出相应安全对策措施.     

基于双色法的层流扩散火焰温度场和烟黑浓度场重构

高温和烟气是火灾事故中造成人员伤亡的两个重要因素,能快速准确地获取火焰温度和烟黑浓度的分布,是对燃烧产热量和发烟量的控制方法进行深入研究的前提。根据双色法的理论基础,结合火焰单元的划分方法,整理并简化了火焰温度和烟黑浓度求解过程。利用自主开发的软件进行重构计算,并选取甲烷/空气轴对称层流扩散火焰为例进行试验。重构结果表明,烟黑浓度和温度的分布在轴向方向上均呈现双峰到单峰的特点。将重构结果和数值模拟的结果进行对比,发现温度峰值和烟黑浓度峰值的相对误差分别低于1.59%和6.08%,表明重构结果和模拟结果具有较好的一致性。因此,可认为该重构方法具有可行性。     

Effects of thermal radiation heat transfer on flame acceleration and transition to detonation in particle-cloud hydrogen flames

The current work examines regimes of the hydrogen–oxygen flame propagation and ignition of mixtures heated by radiation emitted from the flame. The gaseous phase is assumed to be transparent for the radiation, while the suspended particles of the dust cloud ahead of the flame absorb and reemit the radiation. The radiant heat absorbed by the particles is then lost by conduction to the surrounding unreacted gaseous phase so that the gas phase temperature lags that of the particles. The direct numerical simulations solve the full system of two phase gas dynamic time-dependent equations with a detailed chemical kinetics for a plane flames propagating through a dust cloud. It is shown that depending on the spatial distribution of the dispersed particles and on the value of radiation absorption length the consequence of the radiative preheating of the mixture ahead of the flame can be either the increase of the flame velocity for uniformly dispersed particles or ignition either new deflagration or detonation ahead of the original flame via the Zel'dovich gradient mechanism in the case of a layered particle-gas cloud deposits. In the latter case the ignited combustion regime depends on the radiation absorption length and correspondingly on the steepness of the formed temperature gradient in the preignition zone that can be treated independently of the primary flame. The impact of radiation heat transfer in a particle-laden flame is of paramount importance for better risk assessment and represents a route for understanding of dust explosion origin.     

胶合竹材单面受火炭化及温度场试验研究

格鲁班(Glubam)胶合竹材作为一种新型建筑材料,研究其耐火性能并与木材进行比较,对胶合竹材单板及杉木单板分别进行了恒温及ISO 834标准升温条件下的单面受火试验,测得了其炭化速率及不同受火条件下试件内部的温度-时间变化曲线。结果表明,胶合竹材的炭化速率低于杉木,其炭化规律与木材相似,即在受火初期炭化层厚度增加较快,炭化速率较大,随时间延长炭化速率逐渐降低,且受火温度越高,材料的炭化速率越大,同时试验测得在标准火灾条件下,胶合竹材受火20 min的平均炭化速率为0.64 mm/min。此外,通过温度场数据的分析比较发现,胶合竹材的传热速率明显低于杉木,其具有优于杉木的隔热性能,且能够满足相关规范对建筑构件隔热性能的要求。     

火电厂液氨泄漏事故影响分析及对策研究

主要对火电厂液氨泄漏事故后对周围大气环境的影响进行了预测分析研究,并给出了相应安全对策。研究以陕西某电厂2×660MW燃煤机组为例,使用详实可靠的参数对该电厂可能发生的液氨储罐泄漏事故进行了不同气象条件下的风险模拟预测,并根据预测结果画出了可供应急救援参考使用的最不利气象条件下液氨储罐最大可信事故泄漏后不同时刻的影响范围动态图。研究还根据收集到的施工设计资料及参数对200-1000MW级火电厂的液氨泄漏进行了预测,给出各级别火电机组液氨泄漏事故后可能出现的最大致死半径范围。为降低火电厂液氨泄漏风险提出了相应的安全对策和应急救援要求,对避免和减少液氨中毒伤亡事故具有指导意义。     

掘进巷道热环境与通风效率数值模拟研究

井下工作面必须应用通风系统。采用数值模拟技术分析了两种通风方式下,不同风口布置的掘进巷道内空气龄、空气流速和热舒适性指标PMV值的分布情况。根据模拟结果对掘进巷道通风模式的选择提出了建议。结果表明,长距离送风和短距离抽风方式是最有效率的通风模式。压入式通风方式的风口应布置在距掘进头10 m附近,抽出式通风方式抽风口应布置在距掘进头2m范围内。在相同的送风条件下,可增大短距离抽风方式下的送风温度,以提高掘进巷道内热舒适性和降低能耗。     

含磷单体/碳纳米管阻燃改性不饱和聚酯复合材料的制备及其性能研究

以三氯氧磷、苯酚和丙烯酸羟乙酯为原料合成了含磷阻燃单体(DPHE),并作为反应型阻燃剂通过自由基共聚,将其引入不饱和聚酯树脂中,同时添加多壁碳纳米管(MWCNTs),制备不同组分的不饱和聚酯复合材料。采用极限氧指数、UL-94垂直燃烧法表征材料的燃烧性能并评定燃烧等级;通过锥形量热测试数据对材料燃烧过程中的热释放进行研究,结果显示,阻燃不饱和聚酯具有更低的热释放速率峰值(PHRR)和总热释放量(THR)。此外,采用热重分析(TGA)和扫描电子显微镜(SEM)分别对材料的热降解性能和炭渣形貌进行研究,阐明了含磷阻燃单体和多壁碳纳米管的阻燃机理。     

中空玻璃微珠/氮化硼填充硅橡胶复合材料的介电、导热和阻燃性能研究

为满足5G电子封装材料的性能需求,将一定量的改性中空玻璃微珠(f-HGM)和氮化硼(f-BN)添加进加成型液体硅橡胶中制备了低介电、高导热且阻燃的硅橡胶复合材料。测试结果表明,添加了10份f-HGM和15份f-BN的复合材料的介电常数为2.68,介电损耗为0.008 16,显著低于纯硅橡胶,热导率为0.518 W/m·K,是纯硅橡胶的2.25倍。此外,复合材料的热稳定性得到了提升,pHRR和THR分别下降了55.3%和37.7%。通过气相和凝聚相分析发现,复合材料的气相热解产物浓度大幅降低,残炭的致密性和连续性得到显著提升。