Multiple reactor arrangement

A cascade of three continuous stirred-tank reactors arranged in series, is used to carry out an exothermic, first-order chemical reaction. The reactors are jacketed for cooling water, and the flow of water through the cooling jackets is countercurrent to that of the reaction. A variety of control schemes can be employed and are of great importance, since the reactor scheme shows a multiplicity of possible stable operating points. This example is taken from the paper of Mukesh and Rao (1977). 

The position of the transducers in reactors based on the multiple frequency arrangement should be done in such a way that maximum and uniform cavita-tional activity is obtained. Theoretical analysis of the cavitational activity distribution as discussed earlier aids in arriving at an optimum location of the transducers. Similar argument holds true for the geometry of the reactor. 

Another advantage of Liquid Recycle is that multiple reactors may be arranged in series with the effluent from one passing on to the next. The alkene concentration is less in the downstream reactors, but reaction conditions can be adjusted to optimize each reactor s performance. In back mixed reactors in continuous operation, the effluent from the reactor is the same as the catalyst solution throughout the reactor. By placing reactors in series, the first reactor can be optimized for high rates and later reactors for high conversion. 

When larger sizes are required, the design may include multiple units of batch reactors arranged in parallel. 

Figure 26. Alternative arrangements for autothermal reactor design with periodic flow reversal A) Radial-flow concept B) Multiple-bed arrangement...

Fig. 15. Reactor with a multiple-agitator arrangement. 1, turbine impeller 2, baffle 3, cooling and heating coils 4, perforated ring for hydrogen supply. (Bern et al., 1976 also from Chaudhari et al., 1986, by courtesy of Marcel Dekker, Inc.)...

Since the syngas passes over multiple stacks arranged in series, it is only partially converted over each stack and temperature and composition control can be more easily achieved. This is similar to the design intent of the Linde reactor... 

Multiple Solutions Suppose that various sets of reactors could all achieve the same toluene concentration of 0.09 mol/L, but that some reactor arrangements are able to achieve this concentration in a smaller total reactor volume. Is your design still appropriate Understanding the range of different options available to us is useful in selecting the most appropriate reactor configuration for our needs. 

As designed by ICI, the reaction can be conducted in multiple reactors in series with temperatures increasing from 70 to 100" C. In this arrangement, the nitric acid... 

Because the characteristic of tubular reactors approximates plug-flow, they are used if careful control of residence time is important, as in the case where there are multiple reactions in series. High surface area to volume ratios are possible, which is an advantage if high rates of heat transfer are required. It is sometimes possible to approach isothermal conditions or a predetermined temperature profile by careful design of the heat transfer arrangements. 

One of the most frequently used micro reactor types relies on the use of micro-structured platelets with multiple parallel channels, typically manufactured by methods other than routinely used for chip processing, encased in a housing [3,4, 12, 13, 18, 28-39]. If more than one platelet is used, which is usually done to increase throughput, a stack-like arrangement is preferred for parallel feed. Such stacks are either welded directly from the outside [29, 30], are encompassed by a cover [3,18, 31, 32, 37-39], have end caps with fluidic connectors [12,13, 33] or are inserted into a recess of a housing, which is typically composed of two parts [4, 28, 34-36, 40 1]. 

A further improvement was the development of the reactor type unit using multiple tube-and-shell reactors for better temperature control (25). This type of reactor proved useful in larger installations and for selective polymerization of either C3 or C4 olefins only. The larger reactor type units are so arranged that the steam produced in the reactor shell by the exothermic reaction is used to preheat the feed to the proper inlet temperature. The tubes usually are from 2 to 6 inches in diameter. 

In the conventional mechanically agitated reactors, poor dispersion is likely to occur in large units, particularly near the bottom. This can be overcome by using a large L/dT ratio with a horizontal arrangement and multiple impellers. 

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