搅拌槽内固液悬浮和气液分散的实验研究

Experimental study of solid-liquid suspension and gas-liquid dispersion in stirred tank

在实验室提出的新型三相搅拌槽——自吸式龙卷流型搅拌槽中,采用六直叶圆盘涡轮桨进行三相混合性能的实验。从固液悬浮、气液分散和传质性能等方面对搅拌槽进行了研究,探讨了固相颗粒对气含率和传质性能的影响,得到了搅拌槽中不同性能参数的变化规律。结果表明:自吸式龙卷流型搅拌槽作为一种新型的三相搅拌槽,能够获得良好的固液悬浮和气液分散效果;当搅拌槽内固相体积分率较低(φ<20%)时,可采用颗粒的壁面堆积高度作为完全悬浮状态的判定标准;固相颗粒的存在会使气含率明显降低,但对传质性能的影响较为复杂,φ<5%时的体积传氧系数K L a高于纯溶液,φ>5%时的K L a低于纯溶液,但都随固相体积分率的增加而降低。

By using the six straight blades disc turbine impeller, the experiment of mixing characteristics was carried on in a new type of three-phase stirred tank--the self-priming tornado flow stirred tank which was put forward by the lab testing. The tank was studied from aspects of the solid-liquid suspension, gas-liquid dispersion and mass transfer performance, the influence of solid particles on the gas holdup and mass transfer performance was discussed, and the disciplines of the different performance parameters change were concluded in the stirred tank. The results show that the effect of solid-liquid suspension and gas-liquid dispersion is good in the self-priming tornado flow stirred tank, which is used as a new type of three-phase stirred tank. The stack height of particles of the wall can be used as the criteria to judge the complete state of suspension, when the solid phase volume fraction is low （~ 〈 20% ） in the stirred tank. The presence of solid particles can reduce gas holdup obviously, while the influence of which on the mass transfer performance is more complicated. The volumetric oxygen transfer coefficient KLa is higher than that of pure solution when the solid volume fraction is lower than 5%, while it is lower when the solid volume fraction is higher than 5%. But KLa is reduced with the increase of the solid phase volume fraction.