Reactor engineering methodology

Many of the situations encountered by reactor engineers involve (refer to Table 10.1) contact with more than one phase in a stirred tank. It is, therefore, essential to examine whether CFD models can simulate complex multiphase flows in stirred tanks. Here the case of gas-liquid flows in a stirred tank is considered. Similar methodology can be applied to simulate other two-phase or multiphase flows in stirred vessels. The computational snapshot approach discussed previously has been extended to simulate gas-liquid flows (see Ranade et al., 2001c for more details). A two-fluid model was used to simulate gas-liquid flow in a stirred vessel the model equations and boundary conditions are listed below. 

The above list essentially summarizes the tasks performed by a reaction engineer in the development of a new reaction process. The quality of the final result of this reaction engineering methodology, whether automated or not, is intrinsically linked to a necessary hardware component of this process the experimental reactor system. Any shortcomings of this physical system would be manifest as errors or uncertainties in the final reactor design. 

Fig. 37. Summary of reactor selection methodology. The wish list is used to arrive at various decisions on the three reactor subsets. In arriving at the decisions there are several reactor engineering parameters which need to be taken into account these are listed under considerations. ...

A first application of chemical reaction engineering methodology concerns the analysis of the results of laboratory experiments. One of the first things that need to be done is establish the intrinsic kinetics of the chemical reaction(s) under consideration. However, even a small laboratory reactor is large compared to to the length scales of mass transport, such as the dimensions of dispersed particles, dies or striations. That means that transport limitations cannot be excluded a priori and that a complete reactor model may be required for analysing the outcome of laboratory experiments. 

In design, scale-up and scale-down, it is necessary to quantify the effect of various variables on reactor performance (e.g., conversion, selectivity, volumetric productivity, etc.). This is accomplished by utilizing the reaction engineering methodology in developing a reactor model. Such a steady-state model (Figure 1) often contains a description of the reactor idealized flow pattern on the left hand side (LHS) of the chemical species and energy conservation laws i.e. as input-output terms, and the rate... 

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