Liquid circulation in airlift reactors

✍ Scribed by M.Y. Chisti; B. Halard; M. Moo-Young

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 734 KB
• Volume: 43
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(88)87005-2

✦ Synopsis

Energy balance over an airlift loop is used to obtain a theoretical equation [eq. (16)] for the prediction of liquid circulation velocity in those devices. The resulting equation is shown to satisfactorily describe most of the available liquid circulation data (13 different airlift reactors) for a large range of reactor operating scales (0.06-1.06 m3 liquid volumes) including measurements on two pilot scale vessels. The equation applies to both external-and internal-loop types of airlifts over almost two decades of liquid circulation velocities (0.027-1.05 m s-'), reactor height range of 1.368.5 m, and riser-to-downcomer crosssectional area ratios in the range 0.5-9.1. The liquid circulation rate is predicted to increase with the square root of the reactor height. The influence of wall-drag on liquid circulation is shown to be negligible relative to the impact of the frictional losses in the top and bottom connecting sections between the riser and the downcomer where abrupt changes of flow direction take place. Energy dissipation due to wakes behind rising bubbles is most significant.