无消防水池的变电站火灾工况数值模拟研究

当前,建于市区的变电站为了节约用地,其消防系统通常不建设消防水池,消防用水直接从市政管网取水,该消防模式下的取水安全及管网响应情况值得关注.论文以某城市中心城区为例,采用EPANET 2.0构建了供水管网模型,针对供水高峰、流量转输和事故爆管3种不利供水条件,开展了无消防水池变电站的消防系统5种不同火灾工况的水力计算与...     

城市消防安全影响因素及评估体系研究——以海南某沿海城市为例

在前人评估重点研究公共消防基础、灭火救援力量的基础上,增加消防安全形势、火灾防控工作对城市消防安全影响因素的研究,以海南某沿海城市为例,采用层次分析法构建城市消防安全评估体系,设置定量化评分判定基准,运用模糊集值统计法计算得分。评估结果表明体系更真实地反映了该市消防安全现状及火灾防控薄弱环节,最后针对高风险项提出具体改进措施。该体系模型丰富了评估指标数量;宏观考虑了该市热带气候、旅游型城市特征、火灾情况对消防安全形势的影响;更重要的是,提出将社会面火灾防控工作纳入评估体系。研究对于城市消防安全评估的宏观化、系统化、地域化、实用化、定量化都有一定参考意义。     

火灾规律双重性模型及其对室内漏油火灾的分析

火灾的规律具有双重性:确定性和随机性。只有既研究其确定性又研究其随机性,并进而研究二者的综合才能完整地认识火灾的规律。本文提出火灾双重性规律的学术思想,通过构造室内漏油火灾的确定性和随机性模型,阐明运用火灾双重性规律表述火灾过程的具体方法。文中用微机实施的大量计算表明,该模型能方便地预言:发生室内漏油火灾时,室内设备是否会损坏以及可能被损坏的概率.     

Case study on the catastrophic explosion of a chemical plant for production of m-phenylenediamine

On March 21, in Xiangshui County, Yancheng city, China, a catastrophic explosion occurred at Tianjiayi Chemical Co., Ltd. that caused 78 deaths and injured more than 617 individuals, with a property loss of as much as US$ 100 million. An explosion crater with a diameter of 98 m was generated. An extensive consequence analysis based on the crater size and physical effects for the estimation of the quantity of exploded dinitrobenzene (DNB) was performed. By using the position recorded in the satellite photo and the layout of the plant, the crater site was determined to be located near a warehouse where dinitrobenzene was stored. From the scaling law associating the TNT equivalent with crater diameter, the TNT equivalent of exploded ditrobenzene was determined to be approximately 708 tons. Based on the results of the consequence analysis performed by three methodologies, it can be concluded that the Tianjiayi Chemical Co. warehouse not only stored a substantially large quantity of dinitrobenzene but was also located too close to adjacent structures without an adequate separation distance. Judging by the effect of explosive blast on personnel, a fatality radius was determined to be about 400 m from the explosion center.     

Using soybean isoflavone to prevent hydrogen production reaction of aluminium dust and water in wet dust removal systems

Using a dry dust removal system used for aluminium dust collection presents a dust explosion risk, whereas a wet dust removal system presents a risk of hydrogen fire and explosion. Neither system can attain a sufficient level of safety for use at aluminium processing sites. In this paper, soybean isoflavone, a non-toxic and environmentally sustainable flavonoid, was investigated to inhibit hydrogen production from aluminium dust and water. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) were used to characterize aluminium particles before and after the reaction. Soybean isoflavone was found to inhibit hydrogen production from aluminium dust and water. At a soybean isoflavone solution concentration of 2.1 g L⁻¹, a dense protective film resulting from chemical adsorption on the surfaces of the aluminium particles isolated the aluminium particles from water molecules. This film blocked the reaction pathway between the aluminium particles and water to suppress hydrogen generation. This fundamental study addresses the problems of hydrogen fires and explosions in wet dust removal systems for aluminium dust collection and provides a novel, safe and effective method for aluminium dust removal.     

Simulation analysis of fire truck scheduling strategies for fighting oil fires

Emergency response is an important measure to reduce the loss of any major fire and prevent its escalation. There may be many fire trucks participating in the fire-fighting at the same time, and the scheduling of them will affect the fire-fighting efficiency and thus, capacity. This work focuses on the cycle process of fighting fire and refilling water of fire trucks, and analyzes and compares the scheduling strategies of the fire trucks. The simulation tool eM-plant is utilized to model the fire-fighting process. In view of the emergency response in relation to a chemical fire accident and to prevent its escalation, strategies in the analysis consider the allocation of fire trucks according to the distance of hydrants, the distribution of fire trucks according to the number of fire hydrants, etc. The results of this paper show that an even distribution of fire trucks leads to a good performance, but can be further adjusted to find a more optimal strategy. This study provides guidance for fire truck scheduling in case of emergency response.     

Reliability evaluation of fire alarm systems using dynamic Bayesian networks and fuzzy fault tree analysis

In almost all industries, fire alarm systems play a vital role in the reducing the risks associated with fires and damages. Therefore, it is necessary to evaluate their reliability and performance in emergency situations. The present study aimed to use fault tree analysis (FTA) to determine the root causes involved in the failure of fire alarm systems, to use Fuzzy set theory and expert elicitation to determine relative probabilities, and finally, to evaluate the reliability of a fire alarm system using dynamic Bayesian networks (BNs) during a thirty-six months period. A total of 29 basic events were detected from the FT. The reliability of the fire alarm system was estimated at 0.954 according to the FT and 0.957 according to conventional BNs. The reliability of the fire alarm system after 36 months was estimated at 0.375 according to dynamic BNs. All the events involved in the failure of fire alarm systems were drawn in the fault tree diagram. The results indicate that remodeling of these systems and simultaneous construction activities are the most important factors in the failure of the fire alarm system. System reliability can also be increased to 0.965 by providing preventive and control measures to reduce the probability of critical events.     

火源位置对轻型门式刚架竖向位移的影响

为探究总火源功率相同时,两个火源相对位置变化对轻型门式刚架竖向位移的影响规律,采用经实验验证过的有限元方法对其进行瞬态非线性热-结构耦合数值模拟,研究了大功率火灾下单个火源、两个火源位置变化对门式刚架的温度分布以及竖向位移的影响。结果表明:保持火灾总功率30 MW不变时,在单一火源作用下火源位于跨中时刚架位移最大,在两火源作用下,15 MW-15 MW的火源组合最危险、刚架的破坏时间随火源相对距离的增大而增大,功率较大的火源位于临界位置比功率较小的火源位于临界位置有利。且功率较大的火源位于临界位置时,火源相对位置变化对刚架竖向位移的影响不显著,而功率较小的火源位于临界位置时, 影响显著。     

多传感器耦合区域火灾报警技术研究

早期预警与低误报率一直是建筑火灾探测面临的挑战与难题。已有研究多针对特殊场所特定燃烧产物或多种传感器耦合,普适性不强,探测设备成本高,无法大规模应用。通过将火灾烟气蔓延规律与探测器信号时空分布融合,在不增加探测器数量和分布的情况下,提出了一种基于建筑结构微元的多传感器耦合区域火灾报警模型。对典型火灾场景的烟气蔓延情况进行了模拟分析,狭长结构中探测器信号强度变化具有一定的规律性。应用区域火灾报警模型后,报警时间较传统模式提前了14.7%,基本杜绝了单个探测器误报引发建筑物火灾报警的问题。结果表明:多传感器耦合探测模式显著缩短了火灾报警时间,降低了火灾探测误报率,实现了火灾的早期准确识别与预警。     

三相泡沫流动性能及灭油火实验研究

为研究三相泡沫流动性及灭火性能之间的关系,自主搭建了自流动性及灭火实验台架。利用空心玻璃微珠、2000目云母粉、2000目硅微粉及碳酸钙分别制备三相泡沫,检测其流动及灭火性能。实验结果表明,三相泡沫的流动性与其强施放条件下的灭火性能具有一定的关系。通过对比4种不同类别粉体制备的三相泡沫发现,流动性不足的三相泡沫,其灭火时间较长,但抗复燃能力较强;流动过快的三相泡沫,覆盖油面的能力较强,灭火时间较短,但其存在稳定性较差的缺点,可能会导致油品复燃。