Study of ignition and extinction of small-scale fires in experiments with an emulating gas burner

The objective of this study is to explore mechanisms for ignition and extinction for condensed-phase fuels via the use of a gas-fueled burner. Flames were generated with a porous 25 mm circular burner using mixtures of methane and propane with nitrogen. The procedure was to specify a set of mass fluxes of nitrogen-fuel mixture that corresponded to the flash- fire- and extinction points and for the minimum mass flux where steady burning was achieved. The results show an increase in the critical mass flux with a decreased heat of combustion. The data fall into two regimes depending on the mixture flow rate; one buoyancy-driven (Fr<1) and one induced by momentum jet forces. The buoyancy-driven regime is geometrically consistent with the definitions of flash and fire points under natural convection conditions. The results for the momentum regime align reasonably with existing stagnant layer theory. Extinction theory is also suggested to give approximate results for the fire point. This argument is based on similar flame geometries for fire point and extinction and theoretical reasoning. An anchor point is proposed as the end point of ignition. Produced anchor point data result in a flammability diagram, below which quasi-steady burning occurs.     

隧道窑煤气烧嘴调整与烧结质量控制

根据烧嘴的类型、运行特点和烧结过程中常见的质量缺陷,分析产生缺陷的原因,提出相应的工艺调整措施;结合烧结制度与产品性能的关系,探讨制定烧结制度的思路。     

火源对单室轰燃影响的模拟研究

采用FDS模拟热释放速率不同的火源导致单室轰燃的情况。模拟分始终燃烧和火源仅燃烧一段时间两种状况。模拟得出使房间发生轰燃的临界火源热释放速率以及火源热释放速率与发生轰燃时间之间的乘幂函数关系。火源不持续燃烧时火源热释放速率与使房间发生轰燃的临界火源供热时间也存在乘幂函数关系。发生轰燃时间大于喷头动作时间,所以安装喷淋能有效抑制轰燃。     

分析认定起火点和引火源的探讨

准确认定起火点,是正确认定起火原因的前提条件。查清引火源、起火物是认定起火原因的重要保证。探讨分析认定起火点和引火源的条件,提出了应当注意的问题。     

The effect of ignition source exposure and specimen configuration on the fire growth characteristics of a combustible interior finish material

The potential fire hazard presented by plastic based combustible interior finish materials is discussed. Compartment fire experimental methods and apparatus based on Uniform Building Code Standard No. 42-2 were used to study the effect of ignition source exposure and specimen configuration on the actual fire growth characteristics of polyvinyl chloride (PVC) foam wall covering. The results obtained are qualitative in nature, clearly demonstrating two important characteristics of the fire behavior of PVC foam: (i) the PVC foam has a ‘critical’ ignition source strenght of 64–75 kW; (ii) preheating the PVC foam greatly increases its peak net rate of heat release.     

可燃气体最小点火能测试方法与影响因素探讨

对比现有国内外最小点火能测试标准及相关研究。介绍依据ASTM E582-07(2013)建立的球形可燃气体最小点火能测试装置的构成及试验原理、方法。利用该装置开展试验研究,选取甲烷、丙烷（R290）、乙烯,验证装置的可靠性。分析电极间隙与淬熄距离的关系以及电极间隙、初始温度、初始压力等因素对最小点火能的影响。     

FLAMMATECTM天然气燃烧器在玻璃窑炉节能和降低NO_x中的应用

随着石油、天然气价格的不断上升,在玻璃熔窑的天然气的使用越来越引起人们的关注,火焰形状的控制,其辐射和氮氧化物的产生,跟炉口和燃烧器的设计与操作密切相关。本文介绍了一种新型的双喷嘴燃烧器FlammaTecTM Flex,并介绍了其在玻璃窑炉中的应用,结果表明,相对于单喷嘴燃烧器,利用双喷嘴燃烧器可实现对燃烧火焰的精确控制,在天然气–空气燃烧系统中具有广阔的应用前景。     

晋城市燃气过渡气源方案的选择

提出了晋城市过渡补充的三种方案,即长距离输送合成氨放空气方案,压缩煤层气掺混空气分区供气方案和压缩煤层气掺空气混合成氨放空气供气方案,通过对三种方案项目投资的经济性、后期运营的可行性进行分析,最后得出最合理的方案.     

空气源热泵热水系统的技术及经济优势分析

空气源热泵热水系统是太阳能热水系统中比较实用的一种.以下通过对该热泵系统原理的介绍,并与太阳能集热系统、电热水系统的技术经济指标进行分析和比较,结果表明:在我国南方大部分地区建筑内完全采用空气源热泵热水系统可满足生活热水的使用要求.     

Risk analysis of unburnt gas ignition in an exhaust system connected to a confined and mechanically ventilated enclosure fire

The main purpose is to focus on the assessment of an ignition risk due to a large amount of unburnt fuel gases accumulated in the extraction duct connected to a confined and mechanically ventilated enclosure fire combining numeric and experiment. The current numerical study includes the initial well ventilated fire, spreading of flame in the enclosure, subsequent decay during under-ventilated conditions and exhaust of unburnt gas ignition in an extraction duct. Globally, Large Eddy Simulation (LES) combined with an Eddy Dissipation Concept (EDC) combustion model shows the feasibility for simulations of the air vitiation effect on transient combustion events occurring in a closed environment. A particular effort is undertaken to properly predict the pressure level inside a confined facility, and consequently, air inflow supply rate by using a HVAC system. Overall, the numerical results are in fair agreement with the experimental data for the minor species production (CO, H₂), and good agreement for pressure pulse, temperature peak, the major species and heat release rate. In spite of results for minor species that could be improved, the current work confirms the feasibility of a numerical treatment of under-ventilated fire phenomena. The possibility of simulating an ignition risk in an extraction duct connected to a very under-ventilated enclosure fire, has been demonstrated with success in medium-scale facility.     

贵州城市燃气发展及气源优化选择

1贵州城市燃气发展现状贵州省燃气基础设施的建设在近年得到了较大的发展,目前全省使用城市燃气的居民已接近70万户,城镇居民气化率为38.6%,设市城市的气化率已超过50%,但仍低于全国84%的平均水平。2005年贵州省城市燃气供应量为:焦炉煤气1.4亿m3/a(使用城市有贵阳市和六盘水市),天然气(含矿井气)400万m3/a(主要是赤天化使用),液化石油气8万t/a(大多为瓶装供应),此外还有一些工业企业使用水煤气等气源。全省现状城市人口351万人,燃气供应户数达51万户,全省用气人口中煤制气占42.95%,液化石油气占54.38%,天然气占2.67%。2贵阳市焦炉煤气现状2…     

煤气着火爆炸事故火源分析及预防

１概况在燃烧学中,着火有三要素（火源、燃料、空气或氧气）,其中任何一个要素与其它要素分开,燃烧就不能发生或持续进行。煤气是易燃易爆的气体,一旦生产系统发生了着火与爆炸事故,后果不堪设想,这是煤气生产和使用过程中不可忽视的大问题。显然,煤气着火与爆炸事...     

山西省邮政大楼空调冷热源方案经济技术分析

以山西省邮政大楼为工程背景,通过对四种空调系统冷热源方案的设备费、能耗统计、工程费用、土建费用、各类能源增容费、集中供热入网费、运行费用等数据的详细计算,统计出了各方案的初投资和年运行费用,并在对各方案的技术分析的基础上给业主合理选择冷热源,从而保证空调系统合理并经济运行。     

三个来自汉语的靖西壮语名词词缀

文章对靖西壮语中3个来自汉语的名词词缀进行讨论。还对中古汉语借词la:u2131"老"和固有词la:u2132"佬"的区别进行了讨论。     

城镇燃气设施运行、维护和抢修安全技术规程

第二部分(续上期) 3 运行与维护 3.1 一般规定 3.1.1 城镇燃气供应单位对城镇燃气设施的运行与维护应制定下列管理制度和操作规定: 1 安全生产管理制度; 2 城镇燃气管道及其附属系统、场站的工艺管道与设备的运行、维护制度和操作规定;     

中华人民共和国行业标准城镇燃气设施运行、维护和抢修安全技术规程

·第五部分(续上期)· 6液化石油气设施的运行、维护和抢修 6.1一般规定 6.1.1本章所指液化石油气设施包括液化石油气储配站、灌瓶站、气化站、混气站、瓶装供应站和瓶组气化站、储罐、管道及其附件以及压缩机、烃泵、灌装设备、气化设备、混气设备和仪器仪表等.不包括低温储存基地及火车槽车、汽车槽车、槽船等液化石油气专用运输设备和站外液态液化石油气输送管道.     

中华人民共和国行业标准城镇燃气设施运行、维护和抢修安全技术规程

第四部分(续上期) 5生产作业 5.1一般规定 5.1.1 燃气设施的停气、降压、动火及通气等生产作业应建立分级审批制度.作业单位应制定作业方案和填写动火作业报告,并逐级申报;经审批后应严格按批准方案实施.紧急事故应在抢修完毕后补办手续.     

沥青拌合站燃烧器节能改造

分析了沥青拌合站燃烧器的工作原理,为了降低成本、节能减排,对市场进行了调研,更换了更加实用经济环保的燃料,对该燃烧器的控制电路和油路进行了改造,并总结出实际生产中应注意的事项.     

管道内径与壁温对高压氢气自发点火的数值研究

氢气在高压储存中的泄漏容易导致自燃。为探究影响氢气自燃的因素,运用Realizable模型、EDC模型、21步氢/空气化学反应机理对加压氢气在不同管道壁温和管径中突然释放的自燃过程进行了数值模拟。研究结果发现：管道壁温的降低能显著降低氢气自燃的可能性;输送压力小于8 MPa时,管道内径的增加不利于氢气点火自燃,当输送压力过大时（10 MPa）,管道内径的增大为氢气射流的膨胀和扩散提供更多空间,利于氢/空气混合物的生成,促进氢气自燃点火。