Unsteady behaviour of bubble column in homogeneous flow regime: Startup and shutdown

• Published in: Chemical engineering science Vol. 277; p. 118806
• Main Authors: Ruzicka, Marek C., Orvalho, Sandra
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 05.08.2023
• Subjects: Bubble column; Disengagement; Engagement; Experiments; Model; Engagement; Experiments; Disengagement; Bubble column
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2023.118806

[Display omitted] •Startup process (engagement) has two stages, linear and nonlinear.•Shutdown process (disengagement) has one linear stage.•Effect of clear liquid height and gas flow rate is determined.•Typical time-scales of both processes are found to be ∼ 100-101 s.•Mathematical model suggested describes the unsteady behaviour well. The startup (engagement, EN) and shutdown (disengagement, DE) processes in the bubble column are investigated both experimentally and theoretically. Two horizontal interfaces, top and bottom, characterize the evolving bubble bed. Their motion is explored by measurements in a laboratory air–water bubble column operated in the homogeneous flow regime (HoR). The effect of two control parameters is determined: clear liquid height L and gas superficial velocity q. The following results are obtained: the trajectories of the top and bottom interfaces, the duration of the early and late stages of EN, the coordinate points of the typical events of the bubble bed dynamics, the bubble swarm velocities related to the interfaces, the characteristic time scales, the symmetry features of EN and DE processes, the parametric dependence on L and q. A simple mathematical model is suggested to describe and interpret the experimental data.