Ideal Reactors and Their Design Equations

Most chemical reactors used in practice can be classified according to some common criteria and assigned to the so-called basic or ideal reactor types. On the basis of the characteristics of ideal reactors, the complex interactions of chemical reaction kinetics, mass, heat, and impulse transport can be discussed in a general way. The behaviors of many actually used reactors approach the ideal types so that their fundamental relationships can be applied at least for a first reactor design. In other cases, the reactor behavior of real systems must be described with the help of models often containing the ideal reactors as individual elements (see Chapter 3). 

For ideal reactors, highly simplified assumptions are used as the starting point, such as an ideal mixing down to the molecular level or a plug flow (piston type flow pattern). We distinguish between  

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Ideal Reactors and Their Design Equations 37 The space time necessary to achieve a required conversion is ... 

In this chapter, the fundamentals of chemical reaction engineering are presented. The basic definitions along with the material balance of different types of ideal reactors and their design equations are discussed. 

P 0 corresponds to the well-mixed reactor, P to plug flow. Solutions of Equation (12) for a selected set of positive finite values of P fills in the region between the two idealized reactor types. Hlavacek and Hoffman performed the necessary numerical calculations for a few selected values of the parameters and presented their results in a set of plots. Since their plots were intended for illustration rather than for quantatative use in design, I have repeated the calculations for a selected set of parameters. 

Equations (19) and (22) are theoretically pleasing but their practical utility is limited. In a troubleshooting problem eq. (22) would allow us to recover E(s) of the system but we rarely deal with a homogeneous system of linear reactions I In a design problem we often do not know the actual RTD and are trying to design an ideal reactor. If the RTD can be predicted based on a nonideal reactor model, then species concentrations can also be calculated based on that model. Then eq. (22) represents at best only a mathematical short-cut I... 

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