Abstract: Ice sphere made by saturated KCl solution, which can simulate the heavy scraps, are used in water model experiment to study the mechanism of motion and melting of scrap and mixing of the solute of scrap in bottom stirred reactors. The effects of liquid level in single nozzle stirring mode and gas flowrate in double nozzle stirring mode on the motion, melting, and mixing of scraps are investigated. The results show that in the single nozzle stirring mode, when the liquid level is low (the ratio of liquid level to the diameter is 0.42), the stirring of gas column and the circulation in the reactor is weak. As a result, the salt ice sphere moves up and down in the gas column, and the melting of the sphere is relatively slow. With the increase of liquid level (the ratio of liquid level to the diameter is 1.04), the salt ice sphere moves with the circulation. Hence, the melting process is accelerated. However, the mixing time of KCl solution, which is obtained according to the 98% standard, in the reactor is even lower than the melting time of sphere. In the double nozzle stirring mode, the gas flowrate of nozzle A remains unchanged at 0.8 m3/h, and the gas flowrate of nozzle B is 0.5 and 1.0 m3/h, respectively. In the two cases, after the salt ice sphere is added above from nozzle A, the sphere stays at the bottom of the reactor for a period of time. After 60~70 s, the sphere moves to the top and moves along the circulation. When the gas flowrate of nozzle B increases to 1.5 m3/h, the salt ice sphere will not stay at the bottom. It moves with the gas column to the plume area formed by nozzle B and its melting process is accelerated. In all the double nozzle stirring mode cases, it is also found that the mixing time of KCl is lower than the melting time of sphere, which is related to the small mass of sphere and less salt released at the end of melting process. In this study, the effect of double nozzle stirring mode on the acceleration of melting of salt ice sphere is not as good as that of single nozzle stirring with large gas flowrate.

Key words: scrap, water model, motion, melting, mixing, ice

摘要： 通过水模型实验，使用饱和氯化钾溶液制作的冰样模拟重型废钢，研究其在底吹气体搅拌反应器中的运动、融化及溶质的混匀规律。探究了单孔吹气模式下的液面高度、双孔吹气方式下的气体流量等因素对其的影响。结果表明，单孔吹气时，液面高度较低时(液面高度与直径比为0.42)，气柱发展不充分，容器内环流较弱，盐球在气柱上下往复运动，融化较为缓慢。随着液面高度增加(液面高度与直径比为1.04)，盐球随着环流运动，融化过程加快，按照98%标准得到的KCl的混匀时间甚至低于融化时间。双孔吹气时，A孔气体流量0.8 m3/h不变，B孔气体流量为0.5和1.0 m3/h时，盐球从吹气孔A上方加入后，在容器底部停留一段时间，在60~70 s之后才运动到顶部，沿着环流运动；B孔流量增加至1.5 m3/h时，盐球不会在底部停留，随气柱运动到吹气流量大的一侧的羽流区，其融化过程较快。在双孔吹气方案中，也发现了KCl的混匀时间低于融化时间的规律，这和融化末期盐球质量较小，释放的盐分较少有关。在本研究中，双孔吹气对盐球融化的促进作用不如单孔吹气且流量较大的方案。

关键词: 废钢, 水模型, 运动, 融化, 混匀, 冰