Investigations of flow structure and liquid mixing in bubble column equipped with selected internals

- Multiple techniques used elucidated complex flow structure in bubble column equipped with internals.
- Alterations to mixing effects possible with suitable combinations of internals.
- Fast response heat flux probe proved useful tool to allow assessment of internals effects.

Flow structures and liquid mixing effects are examined in a gas sparged column equipped with internals selected to achieve desired effects. The internals used in this study include a concentric tube bundle, a baffle designed to alter flow of bubbles across column cross-section and a multi-arm gas distributor with downward facing holes. The selection represents consideration of heat removal system, minimal obstruction to flow and desirable mixing effects. Measurements have been made in a 0.15 m ID column in two-phase air-water and three phase air-water-glass beads systems. The air flow rate is varied from 0.03 to 0.3 m/s to cover a wide range of velocities and the particles are 40 µm glass beads. Liquid phase mixing effects are examined with tracer injections from which mixing time and axial dispersion coefficients are obtained. For more detailed survey of flow structure neutrally buoyant particles are employed. Measurements with a fast response heat flux probe in two and three phase systems are compared and analyzed to demonstrate its potential use for screening of internals. Averaged flow structure in the presence of the internals is proposed from observations with different techniques.