Rectangular bubble column

In order to verify the simulation results, experiments on bubble behavior in bubble columns are carried out under conditions similar to the simulations. A 3-D rectangular bubble column with the dimension of 8 x 8 x 20 cm3 is used for the experiments. Four nozzles with 0.4 cm I.D. and a displacement of 2.4 cm are designed in the experiments. For single-nozzle experiments, air is injected into the liquid bed through one of the orifices while the others are shut off. The outlet air velocity from the nozzle is approximated using the measured bubbling... 

The above results indicate that, just as in the case of a cylindrical column, the axial dispersion coefficient in a packed rectangular bubble-column depends on the liquid flow rate. The most interesting aspect of this study was that, under... 

Fig. 31. Schematic diagram of a rectangular bubble column with coordinate system.

Parameters Appearing on the Stability Criterion (Bounded Analysis) for Rectangular Bubble Columns Cartesian Coordinates... 

Buwa VV, Ranade VV (2002) Dynamics of gas-liquid flow in a rectangular bubble column Experimental and single/multigroup CFD simulations. Chem Eng Sci 57(22-23) 4715-4736. 

Buwa VV, Ranade W (2002) Dynamics of gas-hquid flow in a rectangular bubble column experimental and single/multigroup CFD simulations. Chem Eng Sci 57(22-23) 4715-4736 Buwa W, Ranade W (2003) Mixing in bubble column reactors role of unsteady flow structures. Canadian J Chem Eng 81(3-4) 402- ll... 

Gupta A, Roy S Euler-Euler simulation of bubbly flow in a rectangular bubble column experimental validation with radioactive particle tracking, Chem Eng J 225 818—836,... 

FIGURE I 1.3 Simulated results for rectangular 2D bubble column (from Pfleger et al., 1999) (a) Time-averaged results, (b) transient results. 

The actual flotation phenomenon occurs in flotation cells usually arranged in batteries (12) and in industrial plants and individual cells can be any size from a few to 30 m in volume. Column cells have become popular, particularly in the separation of very fine particles in the minerals industry and coUoidal precipitates in environmental appHcations. Such cells can vary from 3 to 9 m in height and have circular or rectangular cross sections of 0.3 to 1.5 m wide. They essentially simulate a number of conventional cells stacked up on top of one another (Fig. 3). Microbubble flotation is a variant of column flotation, where gas bubbles are consistently in the range of 10—50 p.m. 

Similarly, the majority of the investigations reported conclude that for both rectangular and cylindrical columns the high frequency instabilities are 3D and have to be resolved by the use of 3D models. Nevertheless, in a few recent papers [5, 6, 21] it has been shown that 2D mixture model formulations can be used to reproduce the time-dependent flow behavior of 2D bubble... 

Sha et al [130, 131] developed a similar multifluid model for the simulation of gas-liquid bubbly flow. To guarantee the conservation of mass the population balance part of the model was solved by the discrete solution method presented by Hagesaether et al [52]. The 3D transient simulations of a rectangular column with dimensions 150 x 30 x 2000 (mm) and the gas evenly distributed at the bottom were run using the commercial software CFX4.4. For the same bubble size distribution and feed rate at the inlet, the simulations were carried out as two, three, six and eleven phase flows. The number of population balance equations solved was 10 in all the simulations. It was stated that the higher the number of phases used, the more accurate are the results. 

Krishna R, van Baten JM (1999) Rise Characteristics of Gas Bubbles in a 2D Rectangular Column VOF Simulations vs Experiments. Int Comm Heat Mass Transfer 26(7) 965-974. 

The most popular PBRs include tubular systems, helical PBRs, plastic bag systems, well systems, pyramid PBRs, airlift PBRs, annular PBRs, colunui PBRs, bubble-colunm PBRs, vertical column PBRs, flat-Plate PBRs, stirred-tank PBRs, rectangular tanks, immobilized bioreactors, and hybrid systems. 

Lewis and Smoley (Ref. 22) studied the plate efficiency in the rectification of mixtures of (1) benzene-toluene, (2) benzene-toluene-xylene, and (3) naphtha and mixtures of pinene and aniline in naphtha. An experimental column 8 in. in diameter with 10 plates spaced 16 in. apart was used. The bubble cap was rectangular, being 2 in. high and 2 in. wide, and extended across the column. There were 24 slots % by Ke on each side of the cap, giving a ratio of slot area to superficial area of about 0.16. The investigators found average plate efficiencies of 60 per cent for the benzene-toluene mixture, 76 per cent for the ternary mixture, and 80 to 95 per cent for the naphtha mixtures. 

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