Gas holdup and bubble behaviour in a pressurized bubble column

The effect of pressure on gas holdup was investigated experimentally with g as-liquid systems, of nitrogen-water, and carbon dioxide-water, in a bubble column with diameter of 45 mm. Single nozzles of 1.4, and 4.0 mm in diamet er were used as gas disperser. When: the 4.0 mm nozzle was used, no effect of pressure on gas holdup was observed. When single nozzle of 1.4 mm with n itrogen as the gas phase, gas holdup increased with pressure. But when carb on dioxide was used as the gas phase, gas holdup showed a maximum at pressu re of 0.6 MPa. The gas holdup at 1.1 MPa was approximately the same value a s that at atmospheric pressure. To explain these phenomena by the behavior of bubbles in the column, bubble size near the wall and bubble frequency at the center of column were measured.