使用氣提法在旋轉填充床中移除氨之研究

Air Stripping of Ammonia in a Rotating Packed Bed

10.6840/cycu201300851

黃小萍

旋轉填充床 ； 氨 ； Ammonia ； Rotating Packed Bed

中原大學化學工程學系學位論文

2013年

碩士

陳昱劭

繁體中文

在水體中，氨對水中生物是有毒性的，目前通常是在高pH值下藉由氣提移除。而RPB的質傳效果佳，可應用於各種氣-液的接觸。因此，本論文主要是探討利用氣提法結合旋轉填充床氣提水中的氨，實驗可分成兩個系統，液體循環式操作與連續式操作，探討移除率受到氣體流率、液體流率、轉速、溫度及pH值等操作參數的影響。從實驗結果得知，在液體循環式操作部分，移除率會受到氣體流率、液體流率、溫度及pH值增加而上升，但受轉速的影響不明顯，其最佳條件為氣體流率50 L/min，液體流率0.3 L/min，pH值為11，溫度57℃，轉速為500 rpm下，操作3小時，移除率可達96%；在連續式操作部分，移除率會受到氣體流率、液體流率及轉速增加而上升，操作在氣體流率70 L/min，液體流率0.1 L/min，pH值為11，溫度60℃，轉速為1500 rpm下，移除率可達87%。 本研究也對此二系統之總括體積氣膜質傳係數（KGa）進行計算，且對文獻中RPB之KGa迴歸式進行比較，結果為本研究所計算之實驗值較低，可能是因為氣提過程中水蒸發造成了KGa低估 另外，與其他設備進行移除率及KGa比較，旋轉填充床可在較短得時間和較低的氣-液比下，即有高移除率。

In aqueous solution, ammonia is toxic and is usually removed by air stripping at high pH value. RPB has found applications in many gas-liquid contacting processes due to its high mass transfer rates. In this study, ammonia removal by air stripping from synthetically prepared ammonia solution in an RPB was performed. Investigated parameters include operating mode, air flow rate, liquid flow rate, temperature, pH value and rotating speed. In the liquid-recirculating experiments, the removal efficiency of ammonia increased with increasing air flow rate, liquid flow rate, temperature and pH value, but the effect of rotating speed was’t significant. The highest removal effiviency was 96%, obtained at a liquid flow rate of 0.3 L/min, an air flow rate of 50 L/min, a pH of 11, a temperature of 57℃ with a operating time of 3 hr. In continuous operation, the removal efficiency of ammonia increased with increasing gas flow rate and rotating speed. At a liquid flow rate of 0.1 L/min, an air flow rate of 70 L/min, a pH of 11, a temperature of 60℃ and a operating time of 5 min, the removal efficiency could achieve 87%. Moreover, the KGa value has been calculated. Compared with the KGa correlation for RPB, the experimental KGa values were lower. This is probably because the water was evaporated during stripping and leads to under-estimation of the removal efficiency ang KGa. Besides, comparing the KGa value and removal efficiency with those in other devices, the result shows that RPB can achieve high removal efficiency in a shorter operating time and lower gas-to-liquid ratio.

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