ノズルおよびオリフィスからの気泡生成に関する実験的研究

第3報: 水銀中の多孔質ノズルからの気泡生成

抄録

Gas injection through a porous nozzle has been widely utilized in many metal refining processes such as steelmaking processes. Measurements of bubble characteristics specified by gas holdup, bubble frequency, mean bubble rising velocity, and mean bubble chord length in actual molten metal baths are very difficult, and accordingly, they have been presumed mainly on the basis of water model experiments. This study was carried out to elucidate whether the bubble characteristics in a molten metal bath can be predicted or not from the information on the behavior of bubbles generated at a porous bottom nozzle placed in a water bath. Mercury was used as the model of molten metal and three kinds of porous nozzles with different pore diameters were employed. Three types of bubble formation patterns were observed with respect to volumetric gas flow rate for each porous nozzle placed in the water bath. The bubble diameter varied over a wide range. In the mercury bath, however, only large bubbles with diameters equivalent to the porous nozzle diameter were generated. This differecne is attributable to the wettability between the porours nozzle and liquid. The bubble characteristics in the mercury bath could not be always predicted from the water model experiments.