吸收过程中界面湍动对传质的影响

Influence of interfacial turbulence on the mass transfer rate in physical absorption processes

传质过程中的界面湍动现象广泛存在 ,宏观上表现为传质阻力下降 ,传质速率增加。本文以甲醇、乙醇等有机溶剂吸收二氧化碳的物理吸收过程为研究对象 ,建立了一套带有激光纹影仪与计算机实时图象采集系统的传质实验装置 ,研究了相界面湍动对传质速率的影响 ,以及液膜厚度变化对相界面湍动情况下传质速率的影响。定义了放大因子 ,利用放大因子定量说明界面湍动对传质速率的影响。实验发现界面湍动存在时 ,液相传质系数与理论值偏离 ,而且随传质推动力的增大 ,偏离增大 ;同样条件下 ,改变液膜厚度 ,传质速率可以成倍的增加。这说明吸收过程中界面湍动对传质的促进作用受多种因素的影响。

Interfacial turbulence is a common feature of mass transfer processes. Mass transfer rate can be enhanced due to interfacial turbulence. A mass transfer experimental equipment with a laser Schlieren system and a computer recorder was set up. The effect of interfacial turbulence on the mass transfer rate in physical absorption processes was investigated quantitatively. The gas used was carbon dioxide and the absorbents were ethanol and methanol. An enhancement factor, which can be used to reflect the influence of interfacial turbulence upon the mass transfer rate, was defined. The measured results show that the value of mass transfer rate is several times larger than that given by the theoretical calculation because of interfacial turbulence. At the same time, it is shown that the enhancement factor will be changed due to alternation of thickness of the liquid film.