Experimental investigation into the impact of sparger design on bubble columns at high superficial velocities

• Published in: Chemical engineering research & design 2016-02, Vol.106, p.205-213
• Main Authors: McClure, Dale D., Wang, Congcong, Kavanagh, John M., Fletcher, David F., Barton, Geoffrey W.
• Format: Article
• Language: English
• Subjects: Bubble column; Hydrodynamics; Mixing; Multiphase flow; Sparger
• ISSN: 0263-8762
• DOI: 10.1016/j.cherd.2015.12.027

•The impact of sparger design on bubble column performance was investigated.•Changes in the orifice diameter led to differences in the homogeneous regime.•At high superficial velocities changing the orifice diameter had minimal impact.•Asymmetry in the sparger design led to a reduction in mixing time. In this work we have quantified the impact of sparger design on the hydrodynamics of a pilot-scale bubble column (0.39m in diameter and 2m in height) at superficial velocities between 0.07 and 0.29m/s. It was found that increasing the sparger orifice diameter from 0.5mm to 3mm led to different behaviour in the homogenous flow regime, this being attributed to the different bubble size distributions (BSDs) generated. At higher superficial velocities (i.e., in the heterogeneous flow regime), it was observed that the sparger orifice diameter had little impact on the column behaviour (as characterised by the BSD, overall hold-up, local hold-up profile, liquid velocity profile and mixing time). Changing from a symmetric to an asymmetric sparger design was observed to have a minimal impact on the BSD and overall hold-up, but a large impact on the flow behaviour (i.e., the local hold-up and liquid velocity profiles). The change in flow patterns caused by the asymmetric sparger generally led to a decrease in the mixing time for all measurement locations and tracer addition points. Results from this work are of clear interest in the design of bubble columns.