【作者】 李铭；

【导师】 李岳；

【作者基本信息】 大连理工大学 ， 安全技术与工程， 2014， 硕士

【摘要】 近年来,有关混合原油储罐燃烧引发火灾的事例层出不穷,而混合原油相比于其他的燃料,其自身的特点使其在燃烧过程中除了稳态燃烧之外还有着特殊的阶段——扬沸。本文建立了小尺寸混合原油火灾实验平台及混合原油火灾稳态阶段数值模型,研究了混合原油油罐火灾的发展阶段与燃烧特性,本文的主要研究工作和结论如下：1.通过火焰形态与油罐内介质温度变化规律将混合原油火灾的发展过程分成四个阶段：(1)稳态燃烧阶段,火焰较为稳定,油品内介质温度持续上升。(2)扬沸前兆阶段,产生烟气量增加,产生沸溢现象,油品温度与油水界面温度出现上下波动。(3)扬沸阶段：产生“轰”的响声,伴随着火焰变亮,火焰高度与宽度迅速增加,短时间内迅速将一部分可燃的油品喷出油罐。油品温度与油水界面温度出现大幅度波动。(4)尾声阶段：火焰亮度减弱明显,很快熄灭。油品温度与油水界面温度迅速减弱。2.本文着重对扬沸阶段的火灾燃烧特性进行了研究,实验得到判定扬沸发生的条件是油水界面层温度在110℃到145℃之间。通过小尺寸实验,得到了混合原油火灾扬沸阶段的影响因素,得到如下结论：(1)影响扬沸强度的主要因素为油罐直径,油品厚度和水垫层厚度。着火油罐直径和油品厚度与扬沸强度呈正相关。水垫层的厚度影响是双方面的,当油量足够时,水垫层越厚扬沸强度越大,而当油量缺乏时,扬沸强度减弱甚至不能发生扬沸。(2)火焰高度方面,油罐直径越小,扬沸时期所能达到的最大高度越大。Thomas公式与稳态阶段的火焰高度吻合度较高。(3)火球直径的影响因素有油罐直径、油层厚度和水垫层厚度,对于小尺寸实验而言,所得影响因素规律与扬沸强度类似。3.建立了FDS小尺寸数值模拟模型进行稳态阶段的数值模拟,通过火焰高度、火焰温度等方面与实验进行对比,证明FDS与实验吻合度较高。在此基础上建立了大型混合原油油罐火灾的数值模拟,得到了大型油罐的火焰温度、热辐射强度的发展与分布规律,并计算得到了30m直径油罐的安全距离为10.1m。更多还原

【Abstract】 Recently more and more mixed crude oil storage tank fire accidents occur. Compared to other fuels, boilover phenomenon always appears during the combustion process besides the steady burning due to the physical-chemical characteristics of the crude oil. A small-scale mixed crude oil fire experiment setup and numerical simulation model were developed to study the combustion process of the mixed crude oil tank. The main contents and conclusions are as follows:1. Four stages were discovered in the combustion process based on the variation of flame shape and medium temperature inside the tank.(1) Steady burning stage:The flame was stable and the temperature of the crude oil continued to rise with time.(2) Boilover precursor stage: The amount of smoke gradually increased. Accompanying by the drastic fluctuations of the temperature of the crude oil and the oil-water interface, boil phenomenon occurred.(3) Boilover stage:Flame brightness was intensified followed a "boom" sound. The flame height and width increased rapidly in a short time. Part of the combustible oil was ejected out of the tank. The temperature of the crude oil and the oil-water interface fluctuated drastically.(4) Ending stage:Flame brightness decreased significantly and the flame was gradually extinguished. The temperature of the crude oil and oil-water interface rapidly decreased.2. The burning characteristics during the boilover stage were specially investigated in the research. The temperature of the oil-water interface (110℃～145℃) was found to be the critical conditions for the occurrence of the boilover. Different influencing factors were examined by the small scale experiment. The conclusions achieved in this part are as follows:(1) Boilover was strongly affected by the tank diameter, the thickness of the oil and the thickness of the water cushion. Boilover was intensified with increasing the tank diameter and the thickness of the oil. For the thickness of the water cushion, when the oil was enough, the thicker the water cushion the greater the boilover intensity. On the contrary, the shortage of oil might lead to the weaken boilover even boilover never occurred.(2) As for as the flame height, the higher maximum height was achived for the smaller diameter tank after boilover. A high degree of flame height was consistent with the steady-state phase of Thomas formula.(3) The fireball diameter was affected by the tank diameter, the thickness of oil and the thickness of the water cushion. Testing results were similar with the boilover intensity for the small scale experiments.3. Steady burning stage was simulated by the developed FDS model, which was approved to be consistent with the experiments. On this basis, the flame temperature and heat radiation intensity of the large-scale mixed crude oil tank model of the were investigated by the developed model From the simulation, the safety distance of30m diameter tank was found to be10.1m.更多还原