Liquid mixing based on convection and turbulent dispersion in bubble columns

A phenomenological model for liquid mixing, that captures the essence of the observed physical phenomena in bubble columns, is presented. In this model, mixing of the liquid phase is considered to be primarily due to convective recirculation and turbulence caused by the rising gas bubbles. The mixing phenomena is thus linked with the hydrodynamics of the flow. The input parameters of the model are obtained using noninvasive experimental techniques, such as Computer Automated Radioactive Particle Tracking (CARPT) and Computer assisted Tomography (CT) to measure the local liquid velocities and void fraction distribution in the system. In addition, it is shown that model parameters can be related to the turbulent eddy diffusivity measurements obtained by CARPT. The model is shown to compare well with tracer data and to reflect a variety of experimental observations. A brief comparison with the axial dispersion model (ADM) and recycle with cross-flow (RCF) model is presented.

[1]  B. G. Kelkar,et al.  LIQUID PHASE BACKMIXING IN BUBBLE COLUMN REACTORS—A NEW CORRELATION , 1994 .

[2]  Jack M. Hochman,et al.  Residence time distributions in recycle systems with crossmixing , 1970 .

[3]  Rajamani Krishna,et al.  A unified approach to the scale-up of gas—solid fluidized bed and gas—liquid bubble column reactors , 1994 .

[4]  Milorad P. Dudukovic,et al.  Chaotic flow in bubble column reactors , 1995 .

[5]  H. Haringa,et al.  Liquid mixing in a bubble column under pressure , 1993 .

[6]  Jyeshtharaj B. Joshi,et al.  Axial mixing in multiphase contactors - a unified correlation , 1980 .

[7]  W. Deckwer,et al.  Mixing and mass transfer in tall bubble columns , 1974 .

[8]  M. Duduković,et al.  Modelling churn-turbulent bubble columns—I. Liquid-phase mixing , 1987 .

[9]  H. F. Svendsen,et al.  Local flow structures in internal loop and bubble column reactors , 1992 .

[10]  M. Baird,et al.  Axial dispersion in large unbaffled columns , 1975 .

[11]  Bubble Column Reactors: Some Recent Developments , 1992 .

[12]  Liang-Shih Fan,et al.  Gas-Liquid-Solid Fluidization Engineering , 1989 .

[13]  Sailesh Kumar,et al.  A γ-ray tomographic scanner for imaging voidage distribution in two-phase flow systems , 1995 .

[14]  M. P. Duduković,et al.  Liquid backmixing in bubble columns via computer-automated radioactive particle tracking (CARPT) , 1993 .

[15]  Milorad P. Dudukovic,et al.  Multiphase Reactors: Models and Experimental Verification , 1991 .

[16]  Gerhart Eigenberger,et al.  Gas—liquid flow in bubble columns and loop reactors: Part I. Detailed modelling and numerical simulation , 1994 .

[17]  M. Duduković,et al.  Flow mapping in bubble columns using CARPT , 1990 .