Bubble column reactors for high pressures and high temperatures operation

The dual effect of viscosity on bubble column hydrodynamics

“…A brief survey of the influence of the temperature over the gas holdup was proposed in refs. (Besagni, 2016;Leonard et al, 2015;Rollbusch et al, 2015) and, in future studies, it would be interesting to investigate whether these results may be interpreted using the dual 1 This statement is based on the scale-up criteria by Wilkinson et al (1992), that are widely accepted. Future studies should be devoted to extend and validate the scale-up criteria listed in the introduction for viscous solutions.…”

“…These contacting devices have found many applications in the chemical production industry and biotechnology thanks to their simplicity of construction, the lack of any mechanically operated parts, low energy input requirements (gas dispersion only and liquid recirculation in some cases), reasonable prices and high performance (i.e., a large contact area between the liquid and gas phase and good mixing within the liquid phase throughout the column) (see refs. (Leonard et al, 2015;Rollbusch et al, 2015)). The heat and mass transfer that occurs in these gas-liquid systems does not necessarily involve reactions between gas and liquid phases, even if this occurs in some cases.…”

Comprehensive experimental investigation of counter-current bubble column hydrodynamics: Holdup, flow regime transition, bubble size distributions and local flow properties

“…For example, Akita and Yoshida (1973) (d c ¼0.152 m, H c ¼2.5 m) observed a negligible effect of U L (up to 0.04 m/s) in both co-current and countercurrent operations. At higher liquid velocities, the column operation influences the holdup: the co-current mode reduces the holdup (Biń et al, 2001;Chaumat et al, 2005b;Jin et al, 2007;Kumar et al, 2012;Otake et al, 1981;Pjontek et al, 2014;Shah et al, 2012;Simonnet et al, 2007), and the counter-current mode increases the holdup (Besagni and Inzoli, 2016a;Besagni et al, 2014Biń et al, 2001;Jin et al, 2010;Otake et al, 1981) as bubbles are either accelerated or decelerated by liquid motion (Leonard et al, 2015;Rollbusch et al, 2015a). Baawain et al (2007) showed that the counter-current or cocurrent operation modes influenced the holdup by approximately 5% in weight, and less than 1% in bubble size, showing that the effect observed is mainly caused by the bubble rise velocity and not only the bubble size.…”

“…We study an air-water bubble column (H c ¼ 5.3 m height and d c ¼ 0.24 m inner diameter, aspect ratio H c /d c 420) and consider gas superficial velocities in the range of 0.004-0.20 m/s and liquid superficial velocities up to À 0.09 m/s. The diameter of the column and its height were chosen considering the well-known scale-up criteria for the results: d c 40.15 m and H c /d c 45 (Kantarci et al, 2005;Leonard et al, 2015). The column diameter classifies this facility as a large-diameter pipe, considering the dimensionless diameter D Ã H proposed by Kataoka and Ishii (1987):…”

“…This regime is characterized by large flow macro-structures with large eddies and widened bubble size distribution owing to the onset of bubble coalescence. The global and local flow properties (and the flow regimes) are also related to the bubble column operation mode: the batch (U L E 0 m/s), the co-current (U L 40 m/s) or the counter-current (U L o 0 m/s) mode (Deckwer, 1992;Leonard et al, 2015;Rollbusch et al, 2015b). Whereas the co-current or semi-batch modes are widely studied, the counter-current mode is significantly less frequently investigated (Leonard et al, 2015).…”