The effect of sparger geometry on gas holdup and regime transition points in a bubble column equipped with perforated plate spargers

• Increasing hole diameter of sparger decreases transition velocities in homogeneous flow regime.
• Increasing hole diameter of sparger decreases total gas holdup in homogeneous flow regime.
• A good agreement between the experiments and the theory of linear stability has been observed.
• A correlation based on dimensionless numbers for the prediction of gas holdup is proposed.
• The average error between the correlation predictions and experimental values remains under 10%.

This paper investigates the effect of sparger geometry on flow regime of a bubble column. The experiments presented in this study were performed under atmospheric pressure with water/air in a cylindrical Plexiglas® column of 33.0 cm i.d. and 3.0 m height. Three different perforated plate spargers were employed. Hole diameter was varied in the range of 1–3 mm, while the free area was 1.0%.The theory of linear stability is used for the prediction of regime transitions in the bubble column and a comparison has been presented between the predictions and the experimental observations. A good agreement between the predictions and the experimental values of transition gas holdup has been obtained.In addition, the data from the literature has been analyzed. Experimental values of transition gas holdups and predictions by the theory of linear stability have been compared with those of literature.A correlation based on dimensionless numbers (Archimedes, Froude, Eötvös and Weber) and the group (do/DC) for the prediction of gas holdup in homogeneous regime is proposed. The average error between the correlation predictions and experimental values remains under ±10%.The proposed correlation is compared with the published data and found to be in fairly good agreement.