A Fundamental Study on Separation Of Wasted Water by Freezing

在第一年中，讨论了搅拌翼的形状、旋转频率盐水温度和分离装置对冰的形状、冰对冷却壁的粘附和分离效率的影响。使用1000 ml乙二醇溶液（10体积%）作为废水。从实验结果中，它被发现，有小的影响翼的形状上的浓度稀释和/或浓缩溶液。此外，通过设定为150 ~ 300 rpm，可以形成几乎不截留浓溶液的冰粒，而不会使冰附着在壁上。第二年，根据上一年的实验结果，制作了新的实验装置。通过使用该装置，在相同的溶液温度和分离时间下，稀溶液的浓度可以从5.7vol%降低到2.5vol%。为了提高分离效率，重要的是浓溶液不被捕获在所形成的冰粒中。因此，使冰粒的尺寸更大是有效的。然后，讨论了预期影响冰粒尺寸的冷却速率（盐水温度）、过冷度和搅拌翼尺寸的影响。在盐水温度为-6 ℃的情况下，稀释溶液的浓度较低，因为分离的冰的量近似等于理想值。然而，人们认识到，随着过冷度的降低和/或搅拌翼尺寸的增加，冰粒的尺寸增加。然而，尚未证实它们对分离效率的显著提高有影响。此外，机翼尺寸的增加使冰形变小。为了抑制对壁的粘附，加入少量的硅烷偶联剂是有用的。

In the first year, influences of a shape of stirring wing, rotational frequency brine temperature and separation apparatus on a shape of ice, an adhesion of ice to a cooling wall and a separation efficiency were discussed. A 1000 ml of ethylene glycol solution(10 vol %) was used as a wasted water. From experimental results, it was found that there was little influence of the wing shape on concentrations of diluted and/or concentrated solutions. Besides, by setting to 150 - 300 rpm, ice particles among which concentrated solution was hardly trapped could be formed without adhesion of ice to the wall.In the second year, a new experimental apparatus was produced on the basis of experimental results of the previous year. By using the apparatus, at the same solution temperature and separation time, the concentration of diluted solution could be reduced from 5.7 vol % to 2.5 vol %.In order to improve the separation efficiency, it is important that concentrated solution is not trapped among formed ice particles. Hence, it is effective that the sizes of ice particles were made to be larger And then, effects of a cooling rate (brine temperature), degree of super-cooling and size of stirring wing which were expected to affect the sizes of ice particles were discussed. In the case of brine temperature at -6 ℃, the concentration of diluted solution was lower because an amount of separated ice was approximately equal to the ideal value. While, it was recognized that sizes of ice particles ; increased as the degree of super-cooling decreased and/or size of stirring wing increased. However, it wasn't confirmed that they affected remarkably improvement of the separation efficiency. Moreover, increase of the wing size made ice shape be flaky. For suppress of adhesion to the wall, it was useful that a small amount of silane-coupler was added.