Batch reactor configuration

Aim of this work was to optimise enzymatic depolymerization of pectins to valuable oligomers using commercial mixtures of pectolytic enzymes. Results of experiments in continuous and batch reactor configurations are presented which give some preliminary indications helpful to process optimisation. The use of continuous reactors equipped with ultrafiltration membranes, which assure removal of the reaction products, allows to identify possible operation policy for the improvement of the reaction yield. 

Establishing the process sensitivity with respect to the above-mentioned factors is crucial for further scale-up considerations. If the sensitivity is low, a direct volume scale-up is allowed and the use of standard batch reactor configurations is permitted. However, many reactions are characterized by a large thermal effect and many molecules are very sensitive to process conditions on molecular scale (pH, temperature, concentrations, etc.). Such processes are much more difficult to scale up. Mixing can then become a very important factor influencing reactor performance for reactions where mixing times and reaction times are comparable, micromixing also becomes important. 

Just like chemical processes, biocatalytic reactions are performed most simply in batch reactors (Figure 5.5a). On a lab scale and in the case of inexpensive or rapidly deactivating biocatalysts, this is the optimal solution. If the biocatalyst is to be recycled, but the mode of repeated batches is to be maintained, a batch reactor with subsequent ultrafiltration is recommended (batch-UF reactor Figure 5.5b). The residence times of catalyst and reactants are identical in all batch reactor configurations. 

A typical batch reactor configuration is shown in Fig. 2-4. The reactor iiself is a cylinder constructed of glass or plastic. The best material for luiiiimizing solute sorption onto the reactor walls should be selected. The choice of material i.s normally based on the solute to be studied. Glass is usual-... 

Fig. 2-4. Typical batch reactor configuration. pH is controlled by a combination pH electrode and automatic buret connected to an autotitrator a syringe sampler allows for removal of a subsample of suspension an addition port permits injection of solute an inert gas is bubbled through the suspension by means of a gas dispersion tube and the system is vented through a gas trap a thermometer allows for temperature monitoring and the suspension is mixed with an overhead stirrer.

This operation contains the time t as an independent process variable, in contrast to all batch reactor configurations. 

OS 89] [R 19] [P 69] Using a special reactor configuration with an interdigital micro-mixer array with pre-reactor, subsequent tubing and a quench, a yield of 95% at 0 °C was obtained [127]. The industrial semi-batch process had the same yield at -70 °C. 

The stirred batch reactors are easy to operate and their configurations avoid temperature and concentration gradient (Table 5). These reactors are useful for hydrolysis reactions proceeding very slowly. After the end of the batch reaction, separation of the powdered enzyme support and the product from the reaction mixture can be accomplished by a simple centrifugation and/or filtration. Roffler et al. [114] investigated two-phase biocatalysis and described stirred-tank reactor coupled to a settler for extraction of product with direct solvent addition. This basic experimental setup can lead to a rather stable emulsion that needs a long settling time. 

Fig. 4.4 Flow sonoelectrochemical reactor in batch recirculation configuration...

Ong SA, Toorisaka E, Hirata M et al (2008) Granular activated carbon-biofilm configured sequencing batch reactor treatment of C.I. Acid Orange 7. Dyes Pigm 76 142-146... 

Figure 4.58 Experimental configuration employed for operation of the basic system in a fed-batch reactor. (.) control lines (----) ...

Figure 4.59 presents the results obtained when the basic system, containing G6PDH and GR, was operated as a fed-batch reactor in the configuration described in Figure 4.58. For comparison, the results of pertinent numerical simulations are also shown. It can be seen that the signal obtained in the experimental system indeed follows the characteristic course shown by the signal calculated, but the actual numerical values are different. This dissimilarity has been attributed to inhibition effects in the reactions involved, effects that were not considered in the calculations. Therefore, a search for potential inhibitors was undertaken.

Example 2-6 Consider the situation where the reactants at constant density are fed continuously into a pipe of length L instead of a tank of volume V as in the batch reactor. The reactants react as they flow down the tube with a speed u, and we assume that they flow as a plug without mixing or developing the laminar flow profile. Show that the conversion of the reactants is exactly the same in these very different reactor configurations. 

Flow-reactor problems are just as simple as batch-reactor problems. In fact, they are the same mathematical problem even though the reactor configuration and operation are totally different. 

Kinetic data are frequently acquired in continuous reactors rather than batch reactors. These data permit one to determine whether a process has come to steady state and to examine activation and deactivation processes. These data are analyzed in a similar fashion to that discussed previously for the batch reactor, but now the process variables such as reactant flow rate (mean reactor residence time) are varied, and the composition will not be a function of time after the reactor has come to steady state. Steady-state reactors can be used to obtain rates in a differential mode by maintaining conversions small. In this configuration it is particularly straightforward to vary parameters individually to find rates. One must of course wait until the reactor has come to steady state after any changes in feed or process conditions. 

J Figure 53 Plot of reactor configurations and Q necessaiy to rnfflirtan a batch reactor, CSTR, aid PFTR. i- isotiiermal. 

As with the catalytic distillation reactor, the chromatographic reactor functions as a multistage reactor. The chromatographic reactor is essentially a batch reactor, and we need to adapt this configuration into a continuous process to develop a large-scale and economic process. 

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