Novel Identifier of Transitions in Bubble Columns Operated with Water and Aqueous Alcohol Solutions

The accurate identification of the transition velocities Utrans in bubble columns (BCs) is very important for their effective design, operation and scale-up. In this work, a novel parameter (new hybrid index (NHI)) has been developed and successfully applied to gas holdup and pressure fluctuations recorded in various BCs operated with water and aqueous solutions of alcohols (ethanol and iso-propanol).
The first Utrans has been identified on the basis of a well-pronounced local NHI minimum, whereas the second Utrans has been distinguished by the point, from which the NHI profile levels off. It has been concluded that the main Utrans depend on the type of gas-liquid system and sparger used. A set of several Utrans has been reported.