Reactors via Computational fluid dynamics

The basic strategy for realizing such performance enhancements is summarized in Table 10-2. The principles can be applied to improving 

Analyze the existing reactor or design Develop alternative versions Evaluate and test the new alternatives 

The engineer is offered a large variety of flow-modeling methods, whose complexity ranges from simple order-of-magnitude analysis to direct numerical simulation. Up to now, the methods of choice have ordinarily been experimental and semi-theoretical, such as cold flow simulations and tracer studies. 

Despite their popularity, these methods normally have an inherent limitation—the fluid dynamics information they generate is usually described in global parametric form. Such information conceals local turbulence and mixing behavior that can significantly affect vessel performance. And because the parameters of these models are necessarily obtained and fine-tuned from a given set of experimental data, the validity of the models tends to extend over only the range studied in that experimental program. 

We illustrate these tasks and activities by applying them to one particular reactor. First, however, we set the stage by summarizing how the steps are carried out for a reactor of any type.  

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Brucato, A., Ciofalo, M., Grisafi, F. and Tocco, R. (2000), On the simulation of stirred tank reactors via computational fluid dynamics, Chem. Eng. Sci., 55, 291-302. 

Marchisio, D. L., Fox, R. O. Barresi, A. A. 2001b On the simulation of turbulent precipitation in a tubular reactor via computational fluid dynamics. Transactions of the Institution of Chemical Engineers 79, 998-1004. 

Instead of using compartment models, the flow pattern in the reactor also can be calculated via computational fluid dynamics (CFD). However, when using CFD, relatively small reaction networks are often used to reduce the computational cost. An exception is gas-phase polymerization, such as the production of low-density polyethylene). For more details on the application of CFD calculations for polymerization processes, the reader is referred to Asua and De La Cal (1991), Fox (1996), Kolhapure and Fox (1999), and Pope (2000). 

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