Bubble column Experimental characterization

Tadaki and Maeda (Tl) examined the desorption of carbon dioxide from water in a bubble-column and analyzed the experimental results under the assumption that while the gas phase moves in piston flow, the liquid undergoes axial mixing that can be characterized by the diffusion model. (Shulman and Molstad, in contrast, assumed piston flow for both phases.) Only poor agreement was obtained between the theoretical model and the experimental... 

Other work has been mainly concerned with the scale-up to pilot plant or full-scale installations. For example, Beltran et al. [225] studied the scale-up of the ozonation of industrial wastewaters from alcohol distilleries and tomato-processing plants. They used kinetic data obtained in small laboratory bubble columns to predict the COD reduction that could be reached during ozonation in a geometrically similar pilot bubble column. In the kinetic model, assumptions were made about the flow characteristics of the gas phase through the column. From the solution of mass balance equations of the main species in the process (ozone in gas and water and pollution characterized by COD) calculated results of COD and ozone concentrations were determined and compared to the corresponding experimental values. 

Experimental Characterization of Cylindrical Bubble Column Flow... 

The sorption number Y introduced by Zlokarnik (3) and defined by eq. (25) presents a reasoneible measure to characterize mass transfer properties of tower bioreactors. Table 1 summarizes experimental studies in bubble columns of various geometry and gives sorption numbers calculated for Uq = 5 cm/s. Besides physico-chemical properties it is particularly the gas distributor which affects the... 

This relation indicates that the apparent viscosity varies depending on the shear rate y. unlike the Newtonian viscosity. Therefore, the definition of the appropriate shear rate characterizing hydrodynamics is required to estimate the effective apparent viscosity for non-Newtonian fluids in bubble columns. In bubble columns, the shear rate is not uniform and unknown. The motion of bubbles results in the wide variation of the shear rate, which is hopelessly complicated and cannot be analyzed. Therefore, the characteristic shear rate should be evaluated on the basis of a simplified physical picture of hydrodynamics in bubble columns and aided by experimental observations. 

Reprinted with permission from Ind.Eng. Chem Fundamentals,14> 75-91(1975). Copyright 1975 American Chemical Society, profiles in the bed coupled with hydrodynamic measurements (38,39), selectivity determinations coupled with careful kinetic characterization (36,37), or unsteady state tracer measurements in columns of different scale (40). A comparison between experimental concentration profiles determined by Chavarie and Grace (38) and the three-phase (i.e. bubble, cloud and emulsion) (20) and two phase (19) bubbling bed models appears in Figure 7. 

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