Chapter 60 – Experimental and modelling study of gas dispersion in a double turbine stirred tank

Publisher Summary Gas dispersion in stirred tanks is very important, since it strongly influences gas–liquid mass transfer. It is an exceedingly complex phenomenon, involving not only the complexity of the continuous phase flow itself, but also the behavior and interactions within the dispersed phase, including bubble breakage and coalescence. This chapter experimentally characterizes gas dispersion in a double turbine stirred tank by measuring local gas holdups and local bubble size distributions throughout the tank. It highlights some modeling problems using a simple compartment model that takes into account bubble breakage and coalescence. Reasonable agreement between experiment and simulation may be achieved with optimization of two parameters. The results however are found to be very sensitive to turbulence data. The model, which uses average bubble sizes, also fails to simulate the smaller average bubble diameters at the bottom of the tank. Population balances on classes of bubbles are required to simulate this phenomenon.