CFD-PBM Simulation on Bubble Size Distribution in a Gas-Liquid-Solid Flow Three-Phase Flow Stirred Tank.

Area of Science:

• Chemical Engineering
• Fluid Dynamics
• Multiphase Flow

Background:

• Understanding gas-liquid-solid flow in stirred tanks is crucial for industrial processes.
• Accurate prediction of bubble dynamics, including size and distribution, is essential for process optimization.

Purpose of the Study:

• To numerically simulate bubble size distribution, location, and gas holdup in a three-phase stirred tank.
• To investigate the influence of rotational speed on gas dispersion characteristics.

Main Methods:

• Employed the Eulerian-Eulerian method coupled with the Population Balance Model (PBM).
• Incorporated bubble aggregation and fragmentation effects on interfacial forces for improved prediction accuracy.

Main Results:

• Increased rotational speed led to a higher content of small-diameter bubbles, concentrated in high-speed regions.
• Small bubbles were found in high fluid velocity areas, while large bubbles were in low hydrostatic pressure zones.
• Specific bubble diameter ranges showed peak content at different rotational speeds (e.g., 0.50-1.90 mm at 2000 rpm).

Conclusions:

• The combined Euler-Euler and PBM approach effectively predicts bubble size distribution and phase holdups.
• Rotational speed significantly influences bubble morphology and gas dispersion within the stirred tank.
• Findings offer guidance for designing forced mineralization devices and understanding bubble dispersion.