Effect of distributor type on microbubble dispersion in a pressurized bubble column

The effect of distributor geometry on bubble characteristics in an air–kerosene system of a pressurized bubble column was evaluated. The experiment was carried out using a cylindrical stainless column with an inner diameter of 0.097 m and a height of 1.8 m under a system pressure up to 3.5 MPa. The gas holdup was calculated under pressure taps from 0.05 m to 0.85 m above the distributor along axial direction of the column. Bubble size was measured with an optical probe installed 0.5 m above the distributor. Perforated plates with four different hole sizes including 0.8 mm (20 each), 1 mm (12 each), 2 mm (3 each), and 3.46 mm (1 each) fixed with the same opening fraction (ϕ_o = 0.128%) were evaluated. Different opening fractions at 0.223% (21 holes), 0.128% (12 holes), 0.074% (7 holes), and 0.032% (3 holes) were also tested with a constant hole size (1 mm). The effect of the distributor geometry on bubble characteristics was determined with seven different types of perforated plates. The number of microbubbles was increased with decreasing opening fraction of the distributor. Based on dynamic gas disengagement (DGD) analysis, microbubbles were rarely generated in all distributors under conditions of P_sys = 0.1 MPa at U_g = 12.3 mm/s. However, a significant number of microbubbles were generated at ϕ_o = 0.032% despite a low flow rate at P_sys = 3.5 MPa. Microbubble ratio varied from 36% to 40% at ϕ_o = 0.128 %, while this ratio varied from 38% to 73% at ϕ_o = 0.032%.