Experimental study on gas-liquid-liquid macro-mixing in a stirred tank
- 作者：Dang Cheng ; Jingcai Cheng ; Xiangyang Li ; Xi Wang ; Chao Yang ; chaoyang@home.ipe.ac.cn ; Zai-Sha Mao
- 关键词：Stirred tank ; Gas&ndash ; liquid&ndash ; liquid ; Mixing ; Dispersion ; Turbulence ; Aeration
- 刊名：Chemical Engineering Science
- 出版年：2012
- 期刊代码：18_00092509
- 类别：ce
- 出版时间：18 June, 2012
- 卷：75
- 期：Complete
- 页码：256-266
- 文件大小：1068 K
摘要
In this paper, experimental data on the mixing time of the continuous phase and power consumption of gas-liquid-liquid dispersions in a mechanically agitated baffled tank are presented. The electrical conductivity method is taken for the measurement of mixing time and the shaft-torque method for power consumption measurement. Tap water is used as the continuous phase, and kerosene and air as the dispersed ones. The effects of probe/tracer injection position, agitation speed, type of impeller, clearance of impeller off tank bottom, oil volume fraction, gas holdup and physical properties of the dispersed liquids on the macro-mixing of the gas-liquid-liquid system have been investigated. The phenomenon of gas-liquid-liquid macro-mixing in a stirred tank is largely similar to that of liquid-liquid and gas-liquid stirred tanks. Our experiments indicate that the gas-liquid-liquid macro-mixing can be enhanced at higher gas holdups while damped at low gas holdups. Contrary to gas effect, the dispersed oil phase at low holdups increases the macro-mixing intensity but at higher holdups decreases the macro-mixing intensity of the continuous phase. The experimental results show that axial impellers are more energy efficient for gas-liquid-liquid macro-mixing than radial impellers. A simple correlation is developed for predicting the mixing time in gas-liquid-liquid three-phase systems and satisfactory agreement with experimental data is observed.