錯流式旋轉填充床中質傳之研究

Abstract

本研究的對象為錯流式旋轉填充床。因為該系統是以氣、液交錯流動的方式進行質傳，故不易發生溢流現象，可操作的氣、液流量範圍則更廣，處理量也更大，符合工業上的要求。 研究中，藉由吸收百分比與總括氣膜體積質傳係數(Kga)探討錯流式旋轉填充床的質傳特性，由實驗結果得知，轉速、液體流量的增加，可使吸收百分比上升，而氣體流量的增加則使得吸收百分比呈現下降現象；至於操作變數對質傳係數的影響，不論轉速、液體流量或是氣體流量的增加都有助於質傳效果提升，若將分佈均勻狀態所得的質傳係數進行廻歸與探討，結果顯示在低轉速(500 rpm)及低液體流量(0.2 L/min)情況，會產生分佈不均勻的現象，導致液體無法利用整個填充床進行質傳，而低估質傳係數，所以在此情況下，氣、液體在填充床內的有效體積利用情形顯得更為重要，因此我們從實驗中，廻歸分析得到有效體積利用率經驗式，藉以描述此現象。

This research is to investigate the characteristics of a cross-flow rotating packed bed. The system has less tendency of flooding due to the flow patern of gas and liquid. As a result, the system can be operated at a higher gas/liquid ratio and is expected more practical for industrial applications. Firstly, we discussed the characteristics of the cross-flow rotating packed bed based on absorption percentage and overall mass transfer coefficient (Kga). According to the experimental results, the absorption percentage increased with both rotational speed and liquid rate, but the increase of gas rate caused the absorption percentage decrease. As to the effects of operation factors on mass transfer coefficients, increase of rotational speed, liquid flow rate and gas flow rate would enhance the efficiency and raise the mass transfer coefficients. The relation between mass transfer coefficients and distribution of liquid in the bed was also discussed. The experimental results showed that at low rotational speed (500 rpm) and low liquid flow rate (0.2 L/min), mal-distribution of liquid might occur. The liquid perhaps only flow through the lower part of the bed, and thus the mass transfer coefficient decreased. An empirical correlation for efficiency of bed usage was obtained.