錯流式旋轉填充床之特性研究

Characteristics of Cross-Flow Rotating Packed Bed

許宜群(Yi-Chun Hsu)

指導教授 ： 劉懷勝

國立臺灣大學/工學院/化學工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.00809

摘要

超重力旋轉填充床是一藉由離心力取代重力之製程強化系統，在離心力場下，它具有如較低的溢流傾向、較高的質傳效率、減少空間及成本等優點，在化學工業中為一重要發展趨勢。

逆流式旋轉填充床已經有較多文獻研究，故本研究主要探討錯流式旋轉填充床內壓降特性，以及利用水吸收VOCs之質傳程序來了解各種操作變因如轉速、流量等對系統內質傳之影響，並藉由系統的設計，探討氣體軸封對於氣體流動以及質傳的影響。

由實驗結果得知，隨著轉速、氣體流量增加會使得系統壓降增加，在低轉速時，乾、濕床兩者壓降差異較小；高轉速時兩者差異較大，而濕床時的壓降略小於乾床，這與逆流式旋轉填充床類似；而隨著轉速、氣體流量、液體流量增加，氣體總括質傳係數會有所提升，初濃度對總括質傳係數幾乎沒有影響；經由分析結果得知系統內氣體濃度分佈是隨著高度遞增而降低，液體濃度分佈是隨著徑向增加而遞增；同時在離心力的作用下，使旋轉填充床比傳統填充床有較好的質傳分離效果；另外由實驗結果亦可得知，在有充足液體及足夠的轉速下，於高氣量時，氣體軸封對質傳效果會有更明顯的提升。

由實驗所得到之質傳係數迴歸，可得以下經驗式

關鍵字

旋轉填充床 ； 質傳 ； 吸收 ； 錯流

並列摘要

Higee is a process which applys centrifugal force to intensify mass and heat transfer. Centrifugal acceleration is beneficial to the process, such as the less tendency of flooding, and the better mass transfer efficiency. As a result, the size of the equipment as well as the capital cost can be greatly reduced, which is a very important trend in future chemical engineering and industrial development.

In this study, the characteristics of pressure drop of a cross-flow rotating packed bed were investigated. Then the absorption of VOCs into water was carried out to evaluate its mass transfer performance. Factors affecting the overall mass transfer coefficient (Kga) such as rotational speed, liquid and gas flow rate were conferred in this research. Besides, the gas flow pattern with the gas seal or not was compared.

According to the experimental results, the pressure drop increased with both gas rate and rotational speed. The difference in pressure drop between wet bed and dry bed in low rotational speed is smaller than that at high rotational speed. In addition, the pressure in wet bed is slightly lower than that in the dry bed. The characteristics of pressure drop in counter current and cross flow rotating beds were found to be similar.

Overall mass transfer coefficient Kga was found to increase with gas rate, liquid rate, and rotational speed. The initial concentration of the gas stream almost did not influence the overall mass transfer coefficient. Due to the effect of centrifugal force, rotating packed bed had better mass transfer than conventional packed bed. From our analysis, the gas concentration decreased with the height of the packed bed, whereas the liquid concentration increased with the radius of the packed bed. With enough liquid flow rate and rotational speed, the overall mass transfer coefficient Kga increased obviously when the gas seal installed.

The empirical correlation for mass transfer coefficient of this cross-flow rotating packed bed was found to be:

並列關鍵字

rotating packed bed ； mass transfer, absorption ； cr

參考文獻

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