Batch Reactors BRs

Runaway criteria developed for plug-flow tubular reactors, which are mathematically isomorphic with batch reactors with a constant coolant temperature, are also included in the tables. They can be considered conservative criteria for batch reactors, which can be operated safer due to manipulation of the coolant temperature. Balakotaiah et al. (1995) showed that in practice safe and runaway regions overlap for the three types of reactors for homogeneous reactions (1) batch reactor (BR), and, equivalently, plug-flow reactor (PFR), (2) CSTR, and (3) continuously operated bubble column reactor (BCR). 

A batch reactor (BR) is sometimes used for investigation of the kinetics of a chemical reaction in the laboratory, and also for larger-scale (commercial) operations in which a number of different products are made by different reactions on an intermittent... 

The general characteristics of a batch reactor (BR) are introduced in Chapter 2, in connection with its use in measuring rate of reaction. The essential picture (Figure 2.1) in a BR is that of a well-stirred, closed system that may undergo heat transfer, and be of constant or variable density. The operation is inherently unsteady-state, but at any given instant, the system is uniform in all its properties. 

The interpretation of cA(t) comes from the realization that each cylindrical shell passes through the vessel as an independent batch. Thus, cA(/) is obtained by integration of the material balance for a batch reactor (BR). Accordingly, we may rewrite equation 16.2-11, in terms of either cA(x) or fA(x), as... 

The discontinuous stirred reactor (Batch Reactor, BR, Fig. 2.1(a)) corresponds to a closed thermodynamic system, whereas the two continuous reactors (Continuous Stirred Tank Reactor, CSTR, Fig. 2.1(b), and Plug Flow Reactor, PFR, Fig. 2.1(c))... 

Fig. 11.9 Types of linear continuous-flow reactors (LCFRs). (a) Continuous plug flow reactor (CPFR) resembling a batch reactor (BR) with the axial distance z being equivalent to time spent in a BR. (b) A tabular flow reactor (TFR) with (tq) miscible thin disk of reactive component deformed and distributed (somewhat) by the shear field over the volume, and (b2) immiscible thin disk is deformed and stretched and broken up into droplets in a region of sufficiently high shear stresses, (c) SSE reactor with (cj) showing laminar distributive mixing of a miscible reactive component initially placed at z = 0 as a thin slab, stretched into a flat coiled strip at z L, and (c2) showing dispersive mixing of an immiscible reactive component initially placed at z — 0 as a thin slab, stretched and broken up into droplets at z — L.

Ideal batch reactors (BRs) including semibatch reactors (SBRs)... 

The batch reactor (BR) is the most intuitively obvious reactor configuration. Much exploratory chemistry is carried out in such reactors, especially at the early stages of the development of a new synthesis. The familiar laboratory beaker into which reagents are introduced to carry out a reaction is perhaps the most commonly used BR. Such simplicity is attractive, but when we come to apply a BR to kinetic studies, additional sophistication must be introduced. Most importantly, we must make sure that temperature and composition are uniform throughout the volume of the reactor. In the commonly employed method of isothermal BR operation, vigorous stirring and temperature control are employed to make sure that the temperature and composition are uniform at a predetermined level throughout the volume of the reactor. 

The batch reactor (BR) is distinct from the PFR and CSTR, which are steady state reactors, in that it is a transient reactor and in both its conventional and its TSR configuration involves a different operating procedure for gathering data. The temperature scanning stream swept reactor (TS-SSR), mentioned in Chapter 5, also requires a modified procedure since it is both a flow and a batch reactor at die same time. Both the TS-SSR and the TS-BR will be discussed separately from the TS-PFR and TS-CSTR. 

Different types of reactors are applied in practice (Figure 1.14). Stirred tank reactors (STR), very often applied for homogeneous, enzymatic and multiphase heterogeneous catalytic reactions, can be operated batchwise (batch reactor, BR), semi-batchwise (semibatch reactor, SBR) or continuously (continuous strirred tank reactor, CSTR)... 

For the purely discontinuous reactor operation the ideally mixed batch-reactor, BR, is used. All educts and solvents are charged initially. Under agitation the mixture is warmed up until the desired process temperature is reached. The reactor is operated at this temperature for a certain reaction time tg, which corresponds to the desired conversion. This is followed by an operational phase to isolate the product. From a safety technical point of view the BR is the reactor causing a maximum of problems, for... 

To understand the underlying principles of these reactors, which are treated in Parts III and IV, we provide the groundwork in this section by considering the basic reactor types. Thus we first describe the batch reactor (BR) most commonly used in organic synthesis and its continuous counterpart, the plug-flow reactor (PFR). These represent one extreme characterized by total absence of backmix-ing from fluid elements downstream in time or space. On the other extreme, we have the fully (or perfectly) mixed-flow reactor (MFR), also called the... 

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