Study of Boilover Suppression by Air Bubble Blowing

人们认为，燃烧泄漏在海面上的石油是迅速清除石油的可能方法之一。但是，沸腾现象是将这种方法付诸实际使用的障碍。作为抑制沸溢的一种方法，提出了通过油层下的水层向油层内吹入气泡，搅动油层，降低两层间的传热速率，并进行了实验验证。首先，在Pyrex玻璃杯式燃烧器上，研究了燃料种类（正庚烷、正庚烷和正十二烷基苯）、燃料或水的初始层厚、杯径等因素对沸腾特性的影响。然后，根据实验结果，研制出能从底部向两层喷吹微细气泡的燃烧器。用该装置测定了燃烧过程中层内温度分布的时间历程和沸溢发生时间t_<bo>1。这段时间被用来 ...更多信息 评估所提出的方法的有效性。主要研究结果如下：1.在所用的三种燃料中，只有十二烷基苯发生沸溢，其沸点（331 ℃）相对高于水.对于十二烷基苯的沸腾：（1）<bo>随着燃料或水的层厚的增加，沸腾时间t_1变长，但水的沸腾时间t_1趋于饱和。(2)随着燃烧器杯直径的增加，<bo>由于燃烧器壁处的热损失减少，t_变得更短。当直径大于60 mm时，它变得恒定。(3)适量的气泡供给可以有效地抑制沸溢。在这种情况下，燃料适度燃烧，几乎完全燃烧，不像发生强烈沸腾的情况下，许多燃料没有燃烧。然而，烟量的减少，这是预期的燃料-空气预混合的效果，并没有得到明确的证实。当空气供给量变大时，火焰在燃料完全消耗之前熄灭。少

Burning up the oil spilled over the sea is considered to be one of the possible ways to remove the oil quickly. But a boilover phenomenon is an obstacle to putting this way to practical use. As a method to suppress boilover we proposed blowing air bubbles into the oil layr through the water layr under it, which might stir the layrs and decrease the heat transfer rate between the two layrs, and made experiments to confirm the effectiveness of this method. First, with the cup-type burner made of Pyrex glass, effects of some factors, such as fuel kind (n-heptane, ethylbenzene and n-dodecylbenzene), initial layr thickness of fuel or water, cup diameter, on the boilover characteristics were investigated. Next, based on the results the burner able to blow fine air bubbles into the two layrs from its bottom was made. With this apparatus the time history of temperature distribution inside the layrs during burning and the boilover occurrence time, t_<bo>, were measured. This time was used to ev … More aluate the effectiveness of the proposed method. The main results are as follows :1. Among the three kinds of fuels used here, boilover occurred only for dodecylbenzene whose boiling temperature (331ﾟC) is relatively higher than that of water.2. Concerning the boliover of dodecylbenzene :(1) The time t_<bo> becomes longer with an increase in the layr thickness of fuel or water, but it tends to be saturated for the latter.(2) With the burner cup diameter, t_<bo> becomes shorter because of the decrease in heat loss at the burner wall. It gets to be constant when the diameter is larger than 60 mm.(3) A proper amount of air bubble supply can suppress boilover effectively. In this case the fuel burned moderately and almost completely, unlike the case of the occurrence of strong boilover where much fuel was left unburned. However the reduction of smoke amount, which was expected from the fuel-air premixing effect, was not definitely confirmed. And when the amount of air supply becomes large the flame was extinguished before the fuel was completely consumed. Less