Bubble column modeling

To simulate the effects of reaction kinetics, mass transfer, and flow pattern on homogeneously catalyzed gas-liquid reactions, a bubble column model is described [29, 30], Numerical solutions for the description of mass transfer accompanied by single or parallel reversible chemical reactions are known [31]. Engineering aspects of dispersion, mass transfer, and chemical reaction in multiphase contactors [32], and detailed analyses of the reaction kinetics of some new homogeneously catalyzed reactions have been recently presented, for instance, for polybutadiene functionalization by hydroformylation in the liquid phase [33], car-bonylation of 1,4-butanediol diacetate [34] and hydrogenation of cw-1,4-polybutadiene and acrylonitrile-butadiene copolymers, respectively [10], which can be used to develop design equations for different reactors. 

In this chapter the elementary hydrodynamic characteristics of simple bubble columns are summarized. Different designs of bubble columns are sketched, and examples of their industrial applications are outlined. An overview of the status on Eulerian bubble column modeling is presented. 

Unfortunately, the present models are still on a level aiming at reasonable solutions with several model parameters tuned to known flow fields. For predictive purposes, these models are hardly able to predict unknown flow fields with reasonable degree of accuracy. It appears that the CFD evaluations of bubble columns by use of multi-dimensional multi-fluid models still have very limited inherent capabilities to fully replace the empirical based analysis (i.e., in the framework of axial dispersion models) in use today [63]. After two decades performing fluid dynamic modeling of bubble columns, it has been realized that there is a limit for how accurate one will be able to formulate closure laws adopting the Eulerian framework. In the subsequent sections a survay of the present status on bubble column modeling is given. 

In several reports on bubble column modeling a constant gas density is employed. This assumption is not consistent for tall columns that are operated... 

Furthermore, in many industrial systems the liquid phase is not operated in batch mode, a continuous flow of the liquid phase has to be allowed. However, due to numerical problems most reports on bubble column modeling introduce the simplifying assumption that the continuous phase is operated in batch mode. Further work is needed on the continuous mode boundary condition. 

The model was later implemented in a commercial code PHOENICS. The input flies specifying the calculations have been deposited in the PHOENICS library of two-phase flow examples [5]. This early bubble column model is included in this book because it is considered particularly useful for educational purposes. 

C Trondheim Bubble Column Model C.2.1 Curvilinear Coordinate Systems... 

C Trondheim Bubble Column Model The Laplacian of a Scalar Field... 

C.4 The 2D Axi-Symmetric Bubble Column Model 1177 The corresponding radial liquid phase momentum balance reduces to ... 

In this section the Trondheim Bubble Column model is discretized using the finite volume technique on a staggered grid. The Trondheim Bubble Column... 

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