Scale bubble column

GL 14] [R 1 ] [P 13] A yield of 85% was obtained by micro flow processing similarly to large-scale bubble column processing [57]. Selectivity was much better since less than 0.05% dichloroacetic acid was formed, whereas conventional processing typically gives 3.5%. 

Laboratory-scale bubble columns for ozonation preferably have a reactor liquid phase volume of VL = 2-10 L, with a height-to-diameter-ratio of hid = 5-10. The ozone/oxygen (ozone/air) gas mixture is supplied through a ceramic or stainless steel porous plate fine pore diffuser (porosity 3,10-40 pm hole diameter). PTFE-membranes are a comparatively new alternative for the ozone gas-to-water transfer (Gottschalk et al., 1998). 

Two-phase gaslwater injector nozzles are mostly used in pilot- or full-scale bubble column applications (Krost, 1995) or in specialized, newly developed reactor types. An example is the Submerged Impinging Zone Reactor (IZR) (Gaddis and Vogelpohl, 1992 Air Products, 1998), which is constructed for very high mass-transfer rates. 

Axial mixing in the liquid, induced by the upflow of the gas bubbles, can be substantial in commercial-scale bubble columns, especially in the chum turbulent regime. Due to typically small particle size, the axial dispersion of the solid catalyst in slurry bubble columns is expected to follow closely that of the liquid exceptions are high-density particles. The liquid axial mixing can be represented by an axial dispersion coefficient, which typically has the form... 

There is no doubt that such state of flow cannot exist in an industrial bubble column of D 1 m. If somebody wanted to scale-down the state of flow of a full-scale bubble column (the same process point in the pi-space) to a laboratory one, one would have to know what parameters in the full-scale bubble column are of real importance. 

Pfleger, D., Gomes, S., Gilbert, N. and Wagner, H.-G. (1999), Hydrodynamic simulations of laboratory scale bubble columns fundamental studies of the Eulerian-Eulerian modeling approach, Chem. Eng. Sci., 54, 5091-5099. 

Figure 4. Effect of air/water volumetric flow ratio on the solvent sublation of PCP on the large-scale bubble column.

Diaz, M. E., Iranzo, A., Cuadra, D. et al. 2008 Numerical simulation of the gas-liquid flow in a laboratory scale bubble column. Influence of bubble size distribution and non-drag forces. Chemical Engineering Journal 139, 363-379. 

Koide, K., Morooka, S., Ueyama, K., Matsuura, A., Yamashita, F., Iwamoto, S., Kato, Y, Inoue, H., Shigeta, M., Suzuki, S., and Akehata, T. (1979), Behavior of bubbles in large scale bubble column, Journal of Chemical Engineering of Japan, 12(2) 98-104. 

The liquid phase velocities in a laboratory scale bubble column of 140 mm in diameter have been measured with a constant temperature anemometer. Data acquisition and analysis have been done by means of a modern process computer. 

Five bubble size distributions were selected from the literature to compare with the binary and cluster coalescence models. Four were measured in small-scale bubble column test sections and one in a sieve tray. Newtonian systems of air-water, oxygen-water, and oxygen-glycol, and a non-Newtonian oxygen-PAA solution were used. The data sets are described in Table 1. The mean bubble diameter is the equivalent diameter of a sphere of equal volume. Bubble shapes are generally ellipsoidal, though larger cap bubbles of -2 cm in diameter appear in several tests. 

FT synthesis. The multishaft bubble column reactor (type D) has also been utilized for the FT synthesis or at least one of the shafts of 6 inch diameter has been utilized by Exxon. Several laboratory-scale bubble column reactors with static mixers have been evaluated for the FT synthesis at the laboratory scale. 

Krishna R. A scale-up strategy for a commercial scale bubble column slurry reactor for Fischer-Tropsch synthesis. Oil Gas Sci. Technol. Rev. 2000 55 359-393. 

Youssef AA, Hamed ME, Grimes JT, Al-Dahhan MH, Dudukovic MP. Hydrodynamics of pilot-scale bubble columns effect of internals. Ind. Eng. Chem. Res. 2013 52 43-55. 

Min JY, Jung HY, Kang SM, Kim YD, Kang YM, Park DJ, Prasad DT, Choi MS (2007) Production of tropane alkaloids by small-scale bubble column bioreactor cultures of Scopolia parviflora adventitious roots. Bioresour Technol 98(9) 1748-1753. doi 10.1016/j. biortech.2006.07.033... 

Kastaneck F, Zahradnik J, Kratochvil J, Cermak J. Modeling of large-scale bubble column reactors for nonideal gas-liquid systems. In Doraiswamy LK, Mashelkar RA, eds. Frontiers in Chemical Reaction Engineering. New York Wiley Eastern, 1984, pp 330-344. 

For those cases that the gas composition does not change appreciably on its passage through the reactor, the same calculation methods can be used as shown above for stirred reactors. The critical variable that has to be controlled is the specific surface area. Since the empirical relations predicting surface areas in stirred reactors are not very accurate (see section 4.6.1,3) it is often desirable to do tests with a small scale bubble column (with a diameter of at least 0.15 m). 

A yield of 85% was obtained with a falling film microreactor, which outperforms large-scale bubble column processing [132]. Selectivity was also superior with <0.05% dichloroacetic add formed. Conventional processing has much higher levels of impurity ( 3.5%). When both, temperature and pressure, were slightly... 

Kato, Y., Inque, H., Shigeta, M., Susuki, S. and T. Akekata (1979) Behavior of Bubbles in Large Scale Bubble Columns , J. Chem. Eng. Japan, 12(2), 98a-101. 

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