The dispersion of the Buncefield oil fire plume: An extreme accident without air quality consequences

The dispersion of pollutants from the huge Buncefield oil depot fire that occurred on 11 December 2005 is simulated using a regional Eulerian chemistry-transport model. We analyse the transport and mixing of the fire plume. We show that the hot plume never reached the ground. Instead, it pierced the thin wintertime boundary layer and was injected into the free troposphere at higher altitudes. This is in agreement with data from many air quality stations. This high injection was fortunate because the fine aerosol particles (PM₁₀) mass column generated by the fire smoke exceeded that of ordinary pollution by an order of magnitude. Our regional chemistry-transport modelling is able to predict the early development of the plume dispersion, as shown by a qualitative comparison between simulated PM₁₀ columns and a satellite image obtained by the EOS-TERRA-MODIS sensor.If the accident had occurred in summer when boundary layers are much deeper and convective, a severe degradation in air quality due to PM₁₀ could have occurred, as shown by a sensitivity simulation assuming a similar fire during one of the hottest days of August 2003. The modelled impact of the fire on regional and European air quality levels strongly depends on the altitude reached by the buoyant plume, as shown by a set of sensitivity simulations with variable injection heights. However, in all cases we found that the fire only affected surface aerosol concentrations without increasing photochemical pollution.     

文丘里水膜除尘器后烟气带水的原因及控制对策

通过对一些文丘里水膜除尘器运行情况的实际调查,分析了烟气带水和风机挂灰振动的可能原因,针对不同情况提出了控制烟气带水危害的可行措施。     

室内准稳态压力火灾烟气沉降模型的改进和实验验证

对室内火灾及烟气的研究给消防工程领域带来了诸多益处,如疏散时间预测、基于性能化的设计分析等。Zukoski (Fireand Materials,1978,2(2): 54-62)在室内火灾烟气运动的开创性研究给出了基于质量和能量平衡的理论方法,为后续研究奠定了基础。然而实验发现,由于忽略热损失偏差,模型对近壁面火源的火灾烟气沉降时间的预测缺乏准确度。本文通过空间重构的方法消除房间长宽比因素造成的热损失偏差,引入两个参数进行表征,以完善该模型。完善后的模型预测烟气沉降时间与实验吻合度非常好,验证了该方法的有效性。在计算分析基础上,将两个参数对模型的影响作了评估,发现其一对模型预测结果的影响远大于另一参数。火源大小确定后,烟气充满房间的时间范围可确定,火源功率越大,时间范围越小。     

An evaluation of measurement methods for organic, elemental and black carbon in ambient air monitoring sites

The carbonaceous components of Particulate Matter samples form a substantial fraction of their total mass, but their quantification depends strongly on the instruments and methods used. United Kingdom monitoring networks have provided many relevant data sets that are already in the public domain. Specifically, hourly organic carbon (OC) and elemental carbon (EC) were determined at four sites between 2003 and 2007 using Rupprecht and Pattashnik (R & P) 5400 automatic instruments. Since 2007, daily OC/EC measurements have been made by manual thermo-optical analysis of filter samples using a Sunset Laboratory Carbon Aerosol Analysis instrument. In parallel, long term daily measurements of Black Smoke, a quantity directly linked to black carbon (measured by aethalometers) and indirectly related to elemental carbon, have been made at many sites. The measurement issues associated with these techniques are evaluated in the context of UK measurements, making use of several sets of parallel data, with the aim of aiding the interpretation of network results. From the results available, the main conclusions are that the R & P 5400 instruments greatly under-read EC and total carbon (TC = OC + EC) at kerbside sites, probably due to the fact that the smaller particles are not sampled by the instrument; the R & P 5400 instrument is inherently difficult to characterise, so that all quantitative results need to be treated with caution; both aethalometer and Black Smoke (converted to black carbon) measurements can show reasonable agreement with elemental carbon results; and manual thermo-optical OC/EC results may under-read EC (and hence over-read OC), whether either transmittance or reflectance is used for the pyrolysis correction, and this effect is significant at rural sites.     

烧烤烟气中挥发性有机物的释放规律及健康风险评价

在用餐高峰期和非高峰期分别对大型烧烤店、中型烧烤店和小型路边烧烤摊排放的烟气进行检测,发现TVOC浓度高峰期达到环境本底值的2~3倍,小型室外烧烤摊>中型烧烤店>大型烧烤店;苯与二甲苯变化规律呈现一定差异性,苯高峰期后浓度呈下降趋势,而二甲苯由于自由基反应减弱浓度缓慢升高,但仍低于高峰期浓度;苯、二甲苯的暴露剂量高峰期大于非高峰期;室外烧烤摊的暴露剂量明显大于大型烧烤店,与中型烧烤店相差不大;整个采样环境下苯不存在较高致癌风险,但仍然存在致癌风险;二甲苯不会对暴露人群造成明显的非致癌健康影响。     

烟尘测试中体积相对误差的校验方法

对在烟尘测试中采样体积相对误差产生的原因进行了分析,提出了检验方法。并通过实例验证了本方法的可行性。     

受限空间烟气运动的盐水模拟实验初探

考虑到盐水在清水中扩散过程与烟气在受限空间内运动的相似性，本文用实验的方法，初步探讨了用盐水的扩散来模拟烟气在建筑物（单室）内运动的可行性。并对烟羽流主轴线速度和顶篷水平分层烟气流厚度的生长规律进行了测量。本文所得结果基本合理，正确，对建筑火灾烟气控制和人员疏散有参考作用．     

霉变对储存水稻燃烧行为影响的研究

储存水稻火灾危险性研究具有重要意义。通过研究霉变对储存水稻燃烧行为的影响,确定其火灾危险性。锥形量热燃烧实验(Cone Test)结果显示,霉变样品可以在更小的外加辐射下被点燃;在四种热辐射(25 kW/m2,35 kW/m2,45 kW/m2,55 kW/m2)下,霉变样品的着火时间(TTI)与火灾性能指数(FPI)均小于未霉变样品;而火灾蔓延指数(FGI)高于未霉变样品。Cone Test结果表明霉变显著提高了储存水稻的火灾危险性。差示扫描量热仪(DSC)测试发现在低温时霉变样品比未霉变时吸热焓值提高了3.6倍,表明其析出了更多的小分子挥发物。结合气相质谱联用(GC-MS)测试确定了霉变样品析出的挥发物中含有醇类, 酯类和醛类等易燃物。采用稳态管式炉(SSTF)进一步研究储存水稻的充分燃烧行为,结果显示热释放量及烟气毒性与样品质量(20 g,40 g)以及一次进气量(10 L/min,20 L/min,30 L/min)有关,霉变对于两者的影响较小。     

多层建筑火灾烟气运动的模拟实验研究

火灾烟气是导致多层建筑火灾中人员伤亡的主要原因。结合多层建筑的实际情况 ,利用缩尺度模型实验楼模拟多层建筑火灾的典型情况 ,对其火灾烟气自火源产生后的运动特性进行实验研究。结果表明 ,烟气沿程由于热交换温度不断降低 ,会迅速达到顶部楼层并立即沉降 ,而且不同工况条件下所包含的有毒成分浓度随着火源温度的升高而上升。实验结果的分析能够较好地符合实际火灾的一些典型调查结果。     

地铁站火灾烟气三维动态场模拟

由于城市地铁的建设在我国迅速发展,地铁站的火灾防范和安全疏散成为一个重要的研究课题。为了探讨地铁站火灾烟气的发展流动规律,笔者根据我国大多数现有地铁站的建筑结构模式建立了双层地铁车站的物理模型,并采用CFD的方法完成了火灾烟流三维动态的场模拟。在模拟中采用Rosseland辐射模型,将火源设定为放热量随时间变化的热源。计算结果表明在没有机械通风的情况下,烟气6分钟就将充满整个地铁站,人员难以在规范要求的时间内安全疏散。该研究成果可以为地铁站火灾发生时人员的安全疏散及烟气的控制提供一定的理论基础。