Gas holdup, bubble behaviour, and mass transfer characteristics in a two‐stage internal loop airlift reactor with different screens

Screen internals were used in a two‐dimensional two‐stage internal loop airlift reactor (ILALR). The influence of screens on the hydrodynamics and mass transfer characteristics in the two‐stage ILALR, including gas holdup, mean bubble diameter, bubble rise velocity, and volumetric mass transfer coefficient (KLa), have been experimentally investigated. It is found that screens can efficiently break bubbles up. Radial bubble velocity distribution is more uniform when screens are installed. Mean bubble diameter with smaller screen pores seems smaller and slightly increases with the increasing of superficial gas velocity Ug. A larger gas holdup and KLa can be obtained when a suitable screen is mounted. The variation trend of overall gas holdup and interfacial area a with Ug is similar. A nearly constant liquid‐side mass transfer coefficient (KL) is found. The empirical correlations for the overall gas holdup and KLa have been proposed, which fit the experimental data well.