NUMERICAL COMPUTATIONS OF TURBULENT GAS-LIQUID DISPERSION IN MECHANICALLY AGITATED VESSELS

The objective of this study is to improve mass transfer models in mech anically-agitated-contactors (MAC). The mass transfer is predicted by using a two-phase two-dimensional computational fluid dynamics (CFD) a pproach. A two-fluid model for two-phase dispersed flow in low gas vol ume fraction MAC is presented herein. Emphasis is placed on the closur e correlations used in this study. Different drag coefficients and sli p velocity correlations for dispersed bubbly flows quoted in the liter ature are studied and compared. Boundary conditions are discussed at t he air injection point and impeller. Simulation results are compared t o the experimental data for overall volumetric mass transfer coefficie nts k(L)a; satisfactory agreement is found on a wide range of operatin g conditions. The experiments were performed in a 0.54 m(3) cylindrica l, non-standard, one-stage reactor, with a flat bottom equipped with a n axial impeller.