A Fundamental Study on Separation Of Wasted Water by Freezing

在第一年，讨论了搅拌翼形状、旋转频率、盐水温度和分离装置对冰的形状、冰与冷却壁的粘附性和分离效率的影响。使用1000毫升乙二醇水溶液(10%体积%)作为废水。实验结果表明，机翼形状对稀溶液和浓溶液的浓度影响不大。此外，当设定为150-300rpm时，可以在不粘着冰的情况下形成浓缩液几乎不被捕获的冰粒。第二年，在前一年的实验结果的基础上，研制了一套新的实验装置。使用该装置，在相同的溶液温度和分离时间下，稀溶液的浓度可从5.7vol%降至2.5vol%。为了提高分离效率，浓溶液不会滞留在形成的冰粒中。因此，使冰粒尺寸变大是有效的，然后讨论了冷却速度(盐水温度)、过冷度和搅拌翼尺寸对冰粒尺寸的影响。在盐水温度为-6℃的情况下，稀释溶液的浓度较低，因为分离的冰量与理想值大致相同。同时，人们认识到冰粒的大小随着过冷度的减小和/或搅拌翼大小的增加而增大。然而，尚不能证实它们对分离效率的显著提高有影响。此外，机翼尺寸的增大使冰的形状变得片状。加入少量硅烷偶联剂可有效抑制胶粘剂的粘附性。

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.