공기-물 혼합물로 조업되는 외부순환형 이중기포탑의 행동에 대한 보다 많은 정보를 얻기 위하여 기체체류량과 총괄부피 산소전달계수 그리고 기포의 수직길이와 속도를 연구하였다. 위의 변수들에 대한 기상유속(0.02-0.18m/s)와 수평연결관 길이(0.1-0.5m)의 영향을 조사하였다. 외부순환형 이중기포탑의 경우, 수평연결관의 길이는 중요한 설계변수였다. 수평연결관 길이의 증가에 따라서 상승관내의 기포의 상승속도와 하강관내의 기포의 하강속도는 순환액체속도의 증가로 인하여 증가하였다. 수평연결관의 길이가 증가함에 따라서 하강관내의 기체체류량과 기표의 수직길이는 상부 연결부위의 기-액 분리능력의 증가 때문에 감소하였다. 수평연결관의 길이가 짧을 때의 외부순환형 이중기포탑내의 총괄부피 산소전달계수가 수평연결관의 길이가 길 때의 값보다 큰 것은 기체체류량이 크기 때문이다.

In other to obtain information on the behavior of the external-loop airlift reactor operation with air-water mixtures, the gas holdup, overall volumetric oxygen mass transfer coefficient, vertical bubble length and bubble velocity were studied. The effects of gas velocity(0.02-0.18m/s)and the length of horizontal connection pipe(0.1-0.5m)with respect to the above mentioned parameters have been investigated. The results showed that the length of the horizontal connection pipe was a dey design parameter for the external-loop airlift reactor. The bubble rising velocity in the riser and bubble downcoming velocity in the downcomer increased due to increase of the circulation liquid velocity as the horizontal connection pipe length was increased. The downcomer gas holdup and vertical bubble length in the downcomer decreased due to increase in gas-liquid separating abilities of upper connection section as the horizontal connection pipe length was increased. The overall volumetric oxygen transfer coefficient in the external-loop airlift reactor with a short connection length was higher than that with a long one due to higher gas holdup.

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