Influence of the gas density on the gas entrainment rate and gas hold-up in loop-venturi reactors

Abstract

The hydrodynamics of a loop-venturi reactor were investigated using a downflow liquid jet ejector. Both the gas entrainment rate of the ejector and the gas hold-up in the main holding vessel were shown to be influenced by the gas density. The amount of volumetrically entrained gas as well as the gas hold-up increase, whilst the average gas bubble diameter in the main holding vessel decreases with higher gas densities. The influence of the gas density on the gas entrainment rate could be explained from the Kelvin-Helmholtz stability analysis. This analysis showed that the initial amplitudes of the surface instabilities on the liquid jet surface ‘are influenced’ by the aerodynamic forces, i.e. a higher gas density results in an increase of the jet width at the plunging point. The increased gas flow observed at higher gas densities could be well explained by this theory.