Bubble column reactors model

Bubble Behavior in a Slurry Bubble Column Reactor Model... 

Smith, D.N., Fuchs, W, Lynn, R.J., and Smith, D.H. (1983), Bubble Behavior in a Slurry Bubble Column Reactor Model, ACS, Washington, DC, USA 526. 

Van der Laan [82] reported attempts to model FT in a bubble column reactor. His model exhibited well-mixed liquid and two gas bubble regimes small bubbles that were well mixed and large bubbles that showed plug flow behavior (Figure 12.21). Van der Laan [82] also provided a summary of bubble column reactor models that others have utilized (Tables 12.1 and 12.2). He concluded that the FT slurry bubble column reactor is reaction controlled due to the low activity of the iron catalyst and the... 

Saxena, S. C., Rosen, M., Smith, D. N., and Ruether, J. A., Mathematical Modeling of Fischer-Tropsch Slurry Bubble Column Reactors, Chem. Eng. Comm., 40 97 (1986)... 

In a bubble-column reactor for a gas-liquid reaction, Figure 24.1(e), gas enters the bottom of the vessel, is dispersed as bubbles, and flows upward, countercurrent to the flow of liquid. We assume the gas bubbles are in PF and the liquid is in BMF, although nonideal flow models (Chapter 19) may be used as required. The fluids are not mechanically agitated. The design of the reactor for a specified performance requires, among other things, determination of the height and diameter. 

Wolf-Dieter Deckwer was working along this line and performed experimental investigations to characterise bubble column reactors without and with suspended catalysts, modelled transport processes and chemical reactions in them. 

Known scale-up correlations thus may allow scale-up even when laboratory or pilot plant experience is minimal. The fundamental approach to process scaling involves mathematical modeling of the manufacturing process and experimental validation of the model at different scale-up ratios. In a paper on fluid dynamics in bubble column reactors, Lubbert and coworkers (54) noted ... 

In this case, the model equations derived for the slurry bubble column reactor are applicable. Note that if the gas-phase concentration is constant, the gas-phase material balance is not needed (where the two reactors have different model equations). 

In the following sections, the solutions of the models as well as various examples will be presented for the case of slurry bubble column reactors. 

Although the most realistic model for a bubble column reactor is that of dispersed plug-flow in both phases, this is also the most complicated model in view of the uncertainty of some of the quantities involved, such a degree of complication may not be warranted. Because the residence time of the liquid phase in the column... 

Orejas, j.A Model evaluation for an industrial process of direct chlorination of ethylene in a bubble-column reactor, Chem. Eng. Sci., 56, 513-522, 2001... 

In the design of upflow, three phase bubble column reactors, it is important that the catalyst remains well distributed throughout the bed, or reactor space time yields will suffer. The solid concentration profiles of 2.5, 50 and 100 ym silica and iron oxide particles in water and organic solutions were measured in a 12.7 cm ID bubble column to determine what conditions gave satisfactory solids suspension. These results were compared against the theoretical mean solid settling velocity and the sedimentation diffusion models. Discrepancies between the data and models are discussed. The implications for the design of the reactors for the slurry phase Fischer-Tropsch synthesis are reviewed. 

As part of the work undertaken by APCI under contract to the DOE, to develop a slurry phase Fischer-Tropsch process to produce selectively transportation fuels, a study of the hydrodynamics of three phase bubble column reactors was begun using cold flow modelling techniques (l ). Part of this study includes the measurement of solid concentration profiles over a range of independent column operating values. 

Pavlica and Olson38 outlined a generalized axial dispersion model for the isothermal bubble-column reactor in which a pseudo-first-order reaction occurred in both the gas and liquid phases. The model considered axial mixing in both the gas and the liquid phases. Here, we review a model for the reactor in which a generalized (m, n)th-order reaction between a gaseous species A and a liquid species C is carried out in the liquid phase. There are many chlorination, nitration, sulfonation, alkylation, and hydrogenation reactions which can be... 

In the section on bubble column reactors, the hydrodynamic parameters needed for scale-up are presented along with models for reaction and heat transfer. The mixing characteristics of colunms are described as are the directions for future research work on bubble column reactors. 

Joshi, J. B. Shah, Y. T. "Hydrodynamic and Mixing Models for Bubble Column Reactors," paper presented at ACS Las Vegas Meeting, August 1980. 

Gasche, H. E., Edinger, C., KOmpel, H., and Hofinann, A fluid-dynamically based model of bubble column reactors. Chem. Eng. Technol. 13,341 (1990). 

With this approach, even the dispersed phase is treated as a continuum. All phases share the domain and may interpenetrate as they move within it. This approach is more suitable for modeling dispersed multiphase systems with a significant volume fraction of dispersed phase (> 10%). Such situations may occur in many types of reactor, for example, in fluidized bed reactors, bubble column reactors and multiphase stirred reactors. It is possible to represent coupling between different phases by developing suitable interphase transport models. It is, however, difficult to handle complex phenomena at particle level (such as change in size due to reactions/evaporation etc.) with the Eulerian-Eulerian approach. 

The recent progress in experimental techniques and applications of DNS and LES for turbulent multiphase flows may lead to new insights necessary to develop better computational models to simulate dispersed multiphase flows with wide particle size distribution in turbulent regimes. Until then, the simulations of such complex turbulent multiphase flow processes have to be accompanied by careful validation (to assess errors due to modeling) and error estimation (due to numerical issues) exercise. Applications of these models to simulate multiphase stirred reactors, bubble column reactors and fluidized bed reactors, are discussed in Part IV of this book. 

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