Continuous stirred tank reactor design equation

As will be shown later the equation above is identical to the mass balance equation for a continuous stirred-tank reactor. The recycle can be provided either by an external pump as shown in Fig. 5.4-18 or by an impeller installed within the reaction chamber. The latter design was proposed by Weychert and Trela (1968). A commercial and advantageously modified version of such a reactor has been developed by Berty (1974, 1979), see Fig. 5.4-19. In these reactors, the relative velocity between the catalyst particles and the fluid phases is incretised without increasing the overall feed and outlet flow rates. 

When reactions 9.3.3 and 9.3.4 take place in a single continuous stirred tank reactor, the route to a quantitative relation describing the product distribution involves writing the design equations for species V and A. 

In contrast to the design equations for batch and plug-flow reactors, eqns. (5) and (62), the design equation for the continuous stirred tank reactor does not contain an integral sign. Figure 14 shows [ A]o/r plotted... 

A simple graphical method may be used to perform many calculations involving continuous stirred tank reactors. From the design equation (130) for one tank... 

Fig. 15. Graphical solution of the design equation for a cascade of continuous stirred tank reactors.

Design Equations for Continuous Stirred-Tank Reactors... 

For steady, continuous stirred-tank reactors, the species-hased design equation is given hy Eq. 4.2.7 ... 

As clearly seen from eq. (10.1 )-(l 0.5) they are independent on the reactor type. The characteristic features of different reactors were discussed in Chapter 1. In Table 10.1 we summarize design equations for batch, fixed bed and continuous stirred tank reactors... 

Table 10.1. Design equations for batch, fixed bed and continuous stirred tank reactors...

In this contribution, we present computer analyses of several selected temperature-programmed desorption (TPD) and temperature-programmed surface reaction (TPSR) experiments in a microreactor flow system operating under atmospheric pressure. The continuous stirred tank reactor (CSTR) and plug flow reactor (PFR) models have been applied for the design equation as... 

Activity. A comparison of the global rates of CO conversion on a per gram of catalyst or on a per gram of cobalt in the catalyst at 500 K shows that the activities of the chromium- and zirconium-doped catalysts were substantially higher than any of the other catalysts studied. (Specific rates on a per active catalyst site basis (13,21) are not available for these catalysts. Such measurements will be undertaken for the more promising catalysts in the near future (22). Justification for this use of the continuous stirred-tank reactor (CSTR) design equation was provided by pulse tracer experiments (20).) These are followed by the activated carbon-... 

Equation (4-51) is the basic design equation for what is popularly called a continuously stirred tank reactor (CSTR). The derivation assumes equality of volumetric flow rate of feed and effluent as in the case of the PFR, the residence-time definition must be changed if this is not so. In most applications of the CSTR, however, reactions in the liquid phase are involved and volume changes with reaction are not important. 

The coimterpart of the ideal plug flow reactor is the ideal continuous stirred-tank reactor with complete backmixing of the rection mass. Because of the ideal mixing, the reaction rate is constant, and a simple design equation is obtained for the catalysis reactor (Eq. 14-3). 

A continuous stirred tank reactor (CSTR) is usually smaller than a batch reactor for a specific production rate (see Fig. 8.4). In addition to reduced inventory, CSTR usually results in enhanced safety, reduced costs, and improved product quality. Tubular reactors offer the greatest potential for inventory reduction since they have the lowest volume for a given conversion when compared to the previous two reactors (see Fig. 8.5). In a fed batch reactor, the reactants are added slowly, thereby controlling the rate of reaction and the exotherm. The design equations for these reactors are as follows ... 

Appendix 3 Summary of Design Equations 61 n. Ideal continuous stirred-tank reactor (CSTR)... 

The definitions of the three ideal reactors, and the fundamentals of ideal reactor sizing and analysis are covered in Chapters 3 and 4. Graphical interpretation of the design equations (the Levenspiel plot ) is used to compare the behavior of the two ideal continuous reactors, the plug flow and continuous stirred-tank reactors. This follows the pattern of earlier texts. However, in this book, graphical interpretation is also used extensively in the discussion of ideal reactors in series and parallel, and its use leads to new insights into the behavior of systems of reactors. 

Consider the schematic representation of a continuous flow stirred tank reactor shown in Figure 8.5. The starting point for the development of the fundamental design equation is again a generalized material balance on a reactant species. For the steady-state case the accumulation term in equation 8.0.1 is zero. Furthermore, since conditions are uniform throughout the reactor volume, the material balance may be... 

The type of optimum reactor that will process 200 m3/hr is a continuous flow stirred tank reactor (CFSTR). This configuration operates at the maximum reaction rate. The volume VR of the reactor can be determined from the design equation ... 

In Chapter 3, the analytical method of solving kinetic schemes in a batch system was considered. Generally, industrial realistic schemes are complex and obtaining analytical solutions can be very difficult. Because this is often the case for such systems as isothermal, constant volume batch reactors and semibatch systems, the designer must review an alternative to the analytical technique, namely a numerical method, to obtain a solution. For systems such as the batch, semibatch, and plug flow reactors, sets of simultaneous, first order ordinary differential equations are often necessary to obtain the required solutions. Transient situations often arise in the case of continuous flow stirred tank reactors, and the use of numerical techniques is the most convenient and appropriate method. 

The various types of reactors employed in the processing of fluids in the chemical process industries (CPI) were reviewed in Chapter 4. Design equations were also derived (Chapters 5 and 6) for ideal reactors, namely the continuous flow stirred tank reactor (CFSTR), batch, and plug flow under isothermal and non-isothermal conditions, which established equilibrium conversions for reversible reactions and optimum temperature progressions of industrial reactions. 

We turn now to consider the principal types of reactors and derive a set of equations for each that will describe the transformation 5 of the state of the feed into the state of the product. The continuous flow stirred tank reactor is one of the simplest in basic design and is widely used in chemical industry. Basically it consists in a vessel of volume V furnished with one or more inlets, an outlet, a means of cooling and a stirrer which keeps its composition and temperature essentially uniform. We shall assume that there is complete mixing on the molecular scale. It would be possible to treat of other cases following the work of Danckwerts (1958) and Zweitering (1959), but the corresponding transformation is much less wieldy. If the reactants flow in and out at a constant rate q, the mean residence time T/g is known as the holding time of the reactor. 

For each of the ideal reactor types, viz. ideal batch reactor, plug-flow reactor (PFR), and continuous-flow stirred-tank reactor (CSTR), continuity equations or design equations can be derived using mass (or rather molar) balance equations for each species involved. 

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