Abstract: Evaporation process for concentrating sea water can be enhanced by bubbling operation, and it is not only significantly influenced by bubble size but also movement of bubbles. Thus, two different sizes of bubbling test rigs were set up indoor and outdoor. The movement, distribution, coalescence and rupture of large bubbles and small bubbles were experimentally analyzed with a single aeration inlet, two aerations inlets and multi-inlets at different gas fluxes, depths and inlet spacings. Small bubbles floating on the liquid surface had higher coverage and scattered more smaller droplets than large bubbles at a lower gas flow flux, implying that the small bubble pattern was more efficient in bubbling for the solar sea water concentration process. The coverage rate of small bubbles in the operation could reach 90%, increasing evaporation rate by 1-1.5 times, based on optimized operational parameters with gas flux at 0.4 L · min^-1, level depth at 8 cm and inlet spacing at 12 cm.

Key words: bubbling, evaporation, mass transfer, concentrated seawater, solar salt

摘要： 鼓泡操作可强化浓海水蒸发过程，其气泡的大小及运动行为对浓海水蒸发过程有显著影响。实验通过搭建两种不同尺寸的鼓泡池，针对单鼓泡口、双鼓泡口及鼓泡阵列，在不同气量、鼓泡口深度与鼓泡口间距条件下，考察大气泡群与小气泡群在不同运动过程的行为。结果表明，在气体流量更低的情况下，液面上的小气泡群比大气泡群具有更高的表面覆盖度，更易于增加液相扰动，并能迸射出更多的小液滴，提出小气泡更适合于鼓泡浓缩晒盐过程。通过单因素实验优化后，小气泡群的覆盖率可以达到90%，蒸发速率可比传统滩晒过程增加1～1.5倍。优化后操作参数为：单鼓泡口气流量为0.4 L·min^-1、鼓泡口深度为8 cm、鼓泡口间距为12 cm。

关键词: 鼓泡, 蒸发, 传质, 浓海水, 晒盐