Continuous stirred tank reactor consecutive reactions

Fig. 1.28. Reactions in series—comparison between batch or tubular plug-flow reactor and a single continuous stirred-tank reactor. Consecutive first-order reactions,...

Fig. 1.27. Reactions in series—single continuous stirred-tank reactor. Concentration CF of intermediate product P for consecutive first-order reactions, A -> P -> Q...

To clarify the above points we consider a simple homogeneous continuous stirred tank reactor (CSTR), in which consecutive exothermic reactions... 

Example 4-8 An ideal continuous stirred-tank reactor is used for the homogeneous polymerization of monomer M. The volumetric flow rate is O, the volume of the reactor is V, and the density of the reaction solution is invariant with composition. The concentration of monomer in the feed is [M]o. The polymer product is produced by an initiation step and a consecutive series of propagation reactions. The reaction mechanism and rate equations may be described as follows, where is the activated monomer and P2, . . , P are polymer molecules containing n monomer units ... 

Cohen, D.S. J.P. Keener. 1976. Multiplicity and stability of oscillatory states in a continuous stirred tank reactor with exothermic consecutive reactions A B C. Chem. Eng. Sci. 31 115-22. 

Pfeil and coworkers presented a model for the synthetic pathway of formose, shown in Scheme 5. A similar, but more detailed, model was given by Mizuno and coworkers, who investigated the intermediates in the reaction by chromatographic fractionation of alditol acetate derivatives by g.l.c. (see Table IV). Weiss and coworkers conceptualized the formose reaction as a consecutive-parallel scheme (see Scheme 6) proceeding to the C level, and reported a series of experiments in the continuously stirred tank-reactor previously mentioned to determine the effect of various concentrations of formaldehyde and calcium hydroxide on the reaction rate. The advantage of the tank reactor is that conversions in the autocatalytic system can be controlled, and reaction rates can be measured directly. When the formaldehyde feed-rate was kept constant, and the feed rate for calcium hydroxide varied, products were obtained... 

It follows from calculations in the proceeding section that the necessa reactor volume of a continuous stirred tank reactor (CSTR) needed to obtain a high degree of conversion is relatively large. A so-called "cascade of CSTR s (a number of CSTR s in series) can be a practical alternative. Let us assume that we replace one CSTR with volume V by a series of n equal CSTR s that have the same total volume. The mean residence time in each reactor is then x/n. We can calculate the relative degree of conversion in each consecutive reactor, for any reaction order, with eq. (3.49), where X is replaced by x/n. We find then for... 

From the kinetic point of view, a BR is often presented as an attractive alternative. For the majority of various kinds of reaction kinetics— simple reactions with approximately elementary reaction kinetics, consecutive reactions, and mixed reactions—the BR gives a higher yield as well as a higher amount of desired intermediate products than a continuous stirred tank reactor (CSTR), and this is why the BR competes with a tube reactor in efficiency. 

ILLUSTRATION 9.3 Quantitative Development of Consecutive Reaction Relationships for a Single Continuous Flow Stirred-Tank Reactor... 

Figure 19.5 Speciation plots for the competitive-consecutive second-order reactions of ammonia and ethylene oxide. Panel PFR plug flow reactor panel CSTR individual continuous flow stirred-tank reactor.

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