低造價間歇式湧升柱之多規格設計與應用研究

Abstract

可利用太陽能微動力進行湖泊水庫水質改善的低造價間歇式湧升柱設備，自侯、葉、林（2004）研發Ⅰ型以來，至2008年已研發至Ⅲ型。本研究延續以上成果，設計Ⅳ至Ⅵ型的多規格湧升柱，並彙整文獻分析各類型湧升柱效能。以上六種規格的湧升柱，主要改變包括空氣室截面積、出水口方式、內管體積等設計因子。 研究結果得知，Ⅰ至Ⅵ型湧升柱的標準曝氣效率(Standard Aeration Efficiency, SAE)分別為0.56、0.72、1.5、1.46、1.52、1.56 kgO2/hr/kw，顯示Ⅲ至Ⅵ型的增氧效率為Ⅰ、Ⅱ型的兩倍以上。Ⅰ至Ⅵ型湧升柱的一次交換水量分別為0.41、0.82、0.61、0.08、0.82、2.86公升。湧升柱的設計因子中，內管體積比、內管徑高比並非影響增氧效率的主要因子；空氣室徑高比應設計大於1，空氣室截面積比與空氣室體積比均需提高至約7，可以有效增加湧升柱的標準曝氣效率至約1.5，提升增氧效率。 於台大醉月湖水深1公尺水區，利用流場分佈判斷湧升柱的攪動水體擴散半徑，Ⅲ型湧升柱為3公尺，Ⅴ型湧升柱為3.5公尺，Ⅵ型湧升柱為5公尺。選用效率最佳之Ⅵ型湧升柱，於醉月湖進行水體改善試驗，其出水口增氧能力，20分鐘約提高水體溶氧1mg/L。Ⅵ型湧升柱於醉月湖1公尺水深水域運作時，單位耗電成本的交換水量最高，約178.8公噸/元。且得知，湧升柱的間歇湧升時間隨入氣速度變大而減小，隨配置水深增加而增大，可利用內插法得到各類型湧升柱在不同配置水深、不同入氣速度的間歇湧升時間。根據本研究成果，日後可依不同水域的水質環境特性與不同改善目的，選擇適當的湧升柱規格進行配置。

The low-cost intermittent air-lift column was devised since 2004 by Hou et al., and three types of air-lift columns were established till 2008. This study designs the other three types of air-lift columns, and analyzes the efficiency of six types. The main changes of the six types mentioned before are the cross-section area of air room, the way of water outlet, the volume of inner tube and so on. From the results of this study, standard aeration efficiency of type Ⅰ to Ⅵ air-lift columns is 0.56, 0.72, 1.5, 1.46, 1.52, 1.56 kgO2/hr/kw. It means that the aeration efficiency of type Ⅲ to Ⅵ air-lift columns is over two times better than type Ⅰ to Ⅱ. Exchanged water volume per one time of type Ⅰ to Ⅵ air-lift columns is 0.41, 0.82, 0.61, 0.08, 0.82, 2.86 liters. Comparing with design factors, ratio of inner tube volume and ratio of diameter and height of inner tube are not main factors which affect aeration efficiency. Ratio of diameter and height of air room should be larger than 1. Ratio of air room cross-section area and ratio of air room volume should be increased to about 7 for advancing the standard aeration efficiency of air-lift column to about 1.5. At Zui-Yue Lake in National Taiwan University where water depth is 1 meter, using distribution of flow field to determine radius of ability of mixing the water volume, type Ⅲ air-lift column is 3 meter, type Ⅴ air-lift column is 3.5 meter and type Ⅵ air-lift column is 5 meter. Select the best air-lift column, type Ⅵ, to proceed the experiment of improving water quality of Zui-Yue Lake. The ability of increasing dissolved oxygen of water outlet of type Ⅵ air-lift column promotes dissolved oxygen of water volume about 1 mg/L in 20 minutes. The max exchanged volume of water per NT dollar of type Ⅵ air-lift column is about 178.8 ton at Zui-Yue Lake where water depth is 1 meter. Otherwise, intermittent time of air-lift column is decreased when pumping velocity increases and increased when water depth increases. We can use interpolation to get intermittent time of different types of air-lift columns at different water depth with different pumping velocities. According to the achievement of this study, we can choose a suitable air-lift column to set up depends on different water qualities and the purpose of environmental improvement in the future.