Fires in very large oil tanks are suppressed by injecting foam into the annular seal ring around the top until the ring is completely filled with foam. However, most of the foam ends up on the unburned area which does not control the fire and results in insufficient supply to the fire region. This paper presents a partition fire extinguishing plan for very large oil tanks that is more efficient and reduces foam use without changing the existing oil tank structure or the fire control system. The scheme was evaluated using an annular oil pan and a small external floating roof oil pan for experimental research on the foam fluidity and partitioned fire control. The results compare the effective covering time, the amount of foam and the fire control time. The results show that the foam spillover into different regions is directly related to the gap width and is not related to the oil pan shape and size. The results also show that the fire control time is shorter when using partitioned areas rather than the unpartitioned design. The partitioned fire control method then reduces the foam use by more than 60%. Experiments with a 3 m diameter oil tank fire are consistent with the results of the annular oil pan experiment, which shows that the advantages of zonal fire control are not related to the tank size and that the partitioned fire control scheme can be applied to very large oil tanks.

为了研发高效干粉灭火剂粉体,提升干粉灭火剂的灭火效果,本文以蛭石粉为研究对象,采用NaCl、NaHCO3、MgCl2和KCl四类离子溶液对不同粒径的蛭石粉进行改性处理,并分析了原始蛭石粉末以及改性后的蛭石粉的膨胀率和表面微观结构.随后开展了ABC干粉灭火剂、未改性蛭石粉、MgCl2改性蛭石粉、NaCl改性蛭石粉、KCl改性蛭石粉、NaHCO3改性蛭石粉扑灭油池火实验,分析了灭火时间、灭火剂用量以及复燃情况.研究结果表明:粒径150μm的蛭石粉末膨胀率最大,且经过改性的蛭石粉末的膨胀率要明显大于原始蛭石粉末,其中MgCl2改性后的蛭石粉膨胀率最大,接近2.4左右;从灭火时间来看,灭火效果从低到高依次为ABC干粉灭火剂、未改性蛭石粉、MgCl2改性蛭石粉、NaCl改性蛭石粉、KCl改性蛭石粉、NaHCO3改性蛭石粉;从灭火剂用量角度可得出:改性蛭石粉灭火用量要明显小于未改性蛭石粉.其中,NaHCO3改性蛭石粉用量与ABC干粉灭火剂用量相对接近.从复燃角度来看,膨胀蛭石粉末的密度较小,可长时间悬浮在油品表面,有效阻止复燃,效果明显优于传统的ABC类干粉灭火剂.

为了研究变压器油初始油温对燃烧特性的影响,搭建了油池火燃烧实验平台,开展了不同初始油温及不同油池直径的池火实验,系统地分析了初始油温对油池火灾发展规律的影响,具体探讨了燃烧发展阶段、燃烧速率以及沸腾层厚度等参数随初始油温的变化规律.结果 表明,变压器油池火的整个发展过程可分为:初始发展阶段、稳定燃烧阶段和火焰熄灭阶段.对于初始发展阶段,随着初始油温的升高,燃烧速率会不断增加,这主要是由于初始油温的升高降低了用于加热油品的热量;对于稳定燃烧阶段,燃烧速率会随着初始油温的升高而增加,但增幅较小.实验尺度范围内,前两个阶段的燃烧速率都会随着燃烧尺度的增加而显著增加.对于稳定燃烧阶段,除了直径20 cm的油池外,变压器油的沸腾层厚度接近2.17 mm,与初始油温无关.因此,在变电站消防设计中,应提高变压器火灾发展初期的灭火效率;同时,采用相应的阻隔措施避免泄漏油品的扩散蔓延.

为研究薄油层燃烧特性,开展航空煤油薄层油池火实验,分析油品燃烧的整个过程、燃烧速率、火焰高度和辐射反馈等参数随时间的变化规律.结果 表明:整个薄层燃烧过程除发展、稳定和熄灭阶段外,还存在薄层燃烧衰减阶段.稳定阶段的燃烧速率与初始油层厚度相关,但随着厚度的增加其逐渐趋于稳定;薄层燃烧衰减阶段,燃烧速率会随着实时油层厚度的下降逐渐降低.对比火焰高度的实测值和模型预测值发现,Heskestad模型的预测更接近实际结果;燃烧发展阶段后,火焰辐射反馈基本维持稳定,受初始厚度的影响较小,但辐射透射强度会随着油层厚度的降低而增加,且增速逐渐加快,表明辐射透射在薄层燃烧衰退阶段中起到关键作用.结合辐射透射的变化规律,将辐射反馈分为可吸收和不可吸收2部分,并提出用于预测辐射透射大小的经验模型.

An index system that can comprehensively evaluate the development of rural fire protection was established.It can not only show the situation of fire safety of the village being evaluated,but also help the village to recognize the contradictions,problems and causes of fire safety clearly,and then propose a solution,as reference in macro-decision for all levels of government work.