Contribution to the study of hydrodynamics and gas–liquid mass transfer in a two- and three-phase split-rectangular airlift reactor

Abstract

Hydrodynamics and gas–liquid mass transfer in a rectangular airlift loop reactor with an internal baffle has been studied in this work. Measurements were carried out for two- and three-phase systems using air–water and air–water–polystyrene particles. The effects of the superficial gas velocity and solid loading up to 15% (v/v) were examined and correlations describing the hydrodynamics and gas–liquid mass transfer behaviours were proposed. The experimental results of mass transfer were compared with those of the literature. It was found in all cases that the gas hold-up in the riser and downcomer and volumetric mass transfer coefficient increased with increasing the superficial gas velocity, while the liquid velocity in the downcomer increased with U gr until 0.033 m s −1 and then decreased to reach a plateau value for U gr > 0.04 m s −1. It was also found that the liquid velocity and the volumetric mass transfer coefficient decreased only with the initial addition of solid for U gr higher than 0.02 m s −1 and that the gas hold-up in the downcomer was significantly influenced by the presence of solid for a concentration above 10% (v/v), while the gas hold-up was almost not affected in the riser. The aeration efficiency was also calculated and was found to be in the range 2.54–4.41 kg O 2/kW h.