共查询到18条相似文献,搜索用时 281 毫秒
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鉴于轻质可燃气体与重质可燃气体在空气中扩散性质的差异 ,本文利用甲烷和氢气的泄漏扩散及其爆炸实验 ,探讨了轻质可燃气体的泄漏扩散行为及爆炸特性。 相似文献
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针对燃气站场混氢输送的安全性问题,基于FLACS软件进行掺氢燃气站场事故情景构建,重点针对气体泄漏、气云爆炸以及喷射火3种典型事故展开后果评估。结果发现:泄漏中后期,气云发展规模增大,气云边界的弥散速度与泄漏速度将达到动态平衡。掺氢比例增加在一定程度上缩短了天然气的爆炸区域,并导致总体泄漏气云量下降。当掺氢比为20%时,气云爆炸产生的超压值最高,危险系数最高。氢气的体积能量较小,掺氢行为会降低气体的能量含量。掺氢比例增加后,喷射火灾的风险范围有所减小。 相似文献
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赵侠 《消防技术与产品信息》2013,(12):37-41
在开放空间细水雾与火焰相互作用研究实验的基础上,进行了细水雾从不同方向施加于竖直向上气体射流火的灭火对比性实验,进而进一步研究细水雾熄灭气体射流火的方法,并结合细水雾灭火实际案例,探讨应用细水雾科学有效的扑救天然气泄漏火灾问题. 相似文献
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《煤气与热力》2021,41(9)
综述国内外掺氢天然气管道输送和终端应用的研究现状,总结天然气管网掺入氢气的主要已知危害和风险,讨论掺氢对终端应用安全性的影响。氢气对输送管道的影响主要来自管材的氢脆现象。对压力较高的管道,氢气的掺入会使钢的断裂韧性减小,加速裂纹扩展,降低疲劳寿命。由于氢气密度小,易扩散,掺氢使气体的渗漏和燃烧爆炸风险增加,且随着掺氢浓度的增加危险程度也逐步增加,泄漏后果的影响需要根据具体的泄漏环境进行分析。掺氢天然气用于家用燃具所造成的主要安全性问题是回火,对于预混式燃烧器,掺氢极限主要取决于回火极限,根据实验结果,在不对燃具做改变的情况下,安全掺氢体积分数不宜超过25%。在工业应用中,由于工业燃烧器具有高度多样性的特点,不同类型燃烧器的最大掺氢量各不相同,因此难以对天然气掺氢带来的影响得出普遍结论,也无法对掺氢浓度制定统一标准。掺氢天然气汽车燃料中的氢气体积分数不应高于18%,混合气体中甲烷体积分数过低,将导致功率大幅度下降,若氢气体积分数超过30%,可能出现发动机爆震的情况。 相似文献
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《Planning》2016,(1)
阐述了熔敷金属中扩散氢的存在形式、产生、来源及危害。介绍了4种扩散氢检测方法,即甘油法、水银法、气相色谱法和载气热提取法,总结了4种检测方法的优劣,并对4种方法进行了比较,指出了4种方法测定扩散氢的差异。简述了焊接热输入、焊接道数、冷却方式及焊接环境等因素对扩散氢含量的影响。 相似文献
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The effects of a material's ignitor characteristics and burning duration on upward wall flame spread are investigated. The ignitor is represented as an energy line source. Its energy release rate and its duration after ignition are considered. The material is represented as a finite, thick noncharring material with properties representative of polymethylmethracrylate (PMMA). A Volterra integral equation is solved for upward flame speed by numerical methods, and a transient, noncharring burning rate model is included. Results show the influence on propagation of ignitor effects and material thickness. A propagation map is computed showing the domains of flames that spread and flames that stop. Criteria for propagation and how propagation affects fire growth are considered in a standard room-corner test. 相似文献
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The need to understand the risks and implications of traffic incidents involving hydrogen fuel cell electric vehicles in tunnels is increasing in importance with higher numbers of these vehicles being deployed. A risk analysis was performed to capture potential scenarios that could occur in the event of a crash and provide a quantitative calculation for the probability of each scenario occurring, with a qualitative categorization of possible consequences. The risk analysis was structured using an event sequence diagram with probability distributions on each event in the tree and random sampling was used to estimate resulting probability distributions for each end-state scenario. The most likely consequence of a crash is no additional hazard from the hydrogen fuel (98.1–99.9% probability) beyond the existing hazards in a vehicle crash, although some factors need additional data and study to validate. These scenarios include minor crashes with no release or ignition of hydrogen. When the hydrogen does ignite, it is most likely a jet flame from the pressure relief device release due to a hydrocarbon fire (0.03–1.8% probability). This work represents a detailed assessment of the state-of-knowledge of the likelihood associated with various vehicle crash scenarios. This is used in an event sequence framework with uncertainty propagation to estimate uncertainty around the probability of each scenario occurring. 相似文献
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为探究粒径对中密度纤维板粉尘爆炸及相关特性的影响,采用20 L爆炸球、粉尘云最低着火温度装置、锥形量热仪和哈特曼管装置,对不同粒径粉尘的爆炸下限、最大爆炸压力、最低着火温度、热释放速率和火焰传播规律进行研究。结果表明,随着粉尘粒径减小,爆炸下限和粉尘云最低着火温度降低,最大爆炸压力逐渐增大;粉尘燃烧过程分为升温、着火、过渡、加剧和熄灭5个阶段,并出现2个峰值,热释放速率变化时间和吸热时间随着粒径减小而增加,热释放速率峰值增大;火焰在管道内的传播随着粒径减小先增强后减弱,管道外“火球”形状更大,火焰消散后火星数量变少,火焰尾端更加细长。 相似文献
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地下储油库是典型的受限空间结构.一旦发生油气爆炸燃烧,爆炸压力波和火焰的传播将受到众多因素的影响.通过数值模拟的方法研究了在地下油料洞库中油气混合物由弱点火引起爆炸燃烧的发展过程,以及爆炸压力波和火焰经局部扰动后的变化过程,并将数值模拟结果与实验结果进行了对比和综合分析,得到了地下油库油气爆炸过程的基本参数,揭示了爆炸过程中油气浓度、湍流对燃烧与压力波发展影响的规律.研究结果对地下受限空间油气爆炸过程的进一步研究以及爆炸灾害的预防都具有参考价值. 相似文献
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The effect of polydisperse water droplet size distribution on the burning behavior and extinction condition of counterflow spray diffusion flame was investigated experimentally in this study. N-heptane as liquid fuel spray and nitrogen as a carrier gas were introduced from the lower duct while water spray and oxidizer consisting of oxygen and nitrogen was issued from the upper duct. The burning behavior of spray flame for different fuel droplet size with and without water spray was observed and the extinction condition of counterflow spray diffusion flame was characterized by oxygen concentration at extinction. The results show that the minimum value of oxygen concentration at extinction for counterflow spray diffusion flame with water spray is similar to the extinction condition without water spray for higher mean droplet diameter of water. The minimum value of oxygen concentration at extinction shifts to the smaller fuel droplet size when decreasing the water droplet size. For fuel droplet size higher than 48 μm, the optimum of water droplet size for suppressing counterflow spray diffusion flame was smaller than gaseous flame. The explanation of optimum water droplet size based on the coupled effect of Stokes number and vaporization Damköhler number can be used for prediction of the effectiveness of water droplet on the suppression of counterflow spray diffusion flame. 相似文献