Reactor configurations and modes of operation

Given the diversity of bioconversion/fermentation processes, different reactor configurations and modes of operation have been developed, so as to provide the more adequate 

In the continuous mode of operation, fresh medium is constantly added to the bioreactor while spent medium is 

---

The remainder of this text attempts to establish a rational framework within which many of these questions can be attacked. We will see that there is often considerable freedom of choice available in terms of the type of reactor and reaction conditions that will accomplish a given task. The development of an optimum processing scheme or even of an optimum reactor configuration and mode of operation requires a number of complex calculations that often involve iterative numerical calculations. Consequently machine computation is used extensively in industrial situations to simplify the optimization task. Nonetheless, we have deliberately chosen to present the concepts used in reactor design calculations in a framework that insofar as possible permits analytical solutions in order to divorce the basic concepts from the mass of detail associated with machine computation. 

V decreases with increasing conversion of A. Thus, if it is possible to remove small amounts of V cheaply from large volumes of the reaction mixture, the optimum reactor configuration and mode of operation would involve the use of a plug flow reactor with low conversions of A per pass coupled with a separator to remove the product V and to recycle unconverted reactants. The exact conversion level to be employed will depend on an economic analysis of the combined reactor-separator system. 

To circumvent mass transfer limitations, shear sensitivity, and equipment footprint problems associated with the scale-up of processes involving anchorage-dependent cells, one may resort to use of cell lines that have been adapted for growth in suspension culture. In such cases, stirred-tank reactors akin to those used in the culture of microorganisms can be employed first in batch and subsequently in fed batch culture of animal cells. Wamock and Al-Rubeai (29) provide useful discussions of the relative merits of stirred tanks and several other reactor configurations and modes of operation that have been used in the manufacture of biopharmaceuticals. During the past half-century, especially in... 

In the preceeding sections it was indicated briefly how to arrive at the appropiate reactor configuration and mode of operation. From these two requirements the reactor type follows automatically, even if it turns out that such a desired reactor type has never been constructed before. 

The integration of the catalyst bed module into the overall reactor model depends largely on the configuration of the reactor system and the mode of its operation. In principle, the adiabatic single bed reactor is the simplest since for this configuration and mode of operation the catalyst bed module represents the overall... 

The success of an ISPR process does not depend only on the chosen separation technique but also on the configuration of the bioreactor/separation units and mode of operation. Previous reviews have shown the various possible modes of operation (continuous, batch) and the use of a separation unit outside of the reactor or separation techniques that act right inside the fermenter [19,22,31]. Freeman and coworkers introduced a classification scheme for ISPR process based on batch/continuous operation and internal (within the reactor)/external (outside the reactor) removal of the product [3]. 

A chemical reactor is an apparatus of any geometric configuration in which a chemical reaction takes place. Depending on the mode of operation, process conditions, and properties of the reaction mixture, reactors can differ from each other significantly. An apparatus for the continuous catalytic synthesis of ammonia from hydrogen and nitrogen, operated at 720 K and 300 bar is completely different from a batch fermenter for the manufacture of ethanol from starch operated at 300 K and 1 bar. The mode of operation, process conditions, and physicochemical properties of the reaction mixture will be decisive in the selection of the shape and size of the reactor. 

There are five primary reactor designs based in theory batch, semibatch, continuous-stirred tank, plug flow, and fluidized bed. The operating expressions for these reactors are derived from material and energy balances, and each represents a specific mode of operation. Selected reactor configurations are presented in Fig. 1. 

The primary glow discharge reactor in this configuration could be used for plasma coating in a low-pressure regime, in principle however, in consideration of flow pattern in such a multiple shelves reactor and electrical field in multiple electrodes, it is difficult to achieve uniform coatings in such a mode of operation. 

On the basis of the kinetics of the biocatalysts and the foregoing decisions, the reactor configuration must then be chosen standard or novel Here, availability, experience, desired mixing, and mass-transfer properties play a dominant role. The mode of operation of the bioreactor can be (fed-)batch or continuous. In making this decision, the kinetics, stability and form of the biocatalyst, desired substrate conversion and product concentration, and need for process control all play a role. 

Even when the above two subsets I and II have been decided, the definition of the reactor configuration is not complete there remains the choice of the appropriate gas-solid fluidization regime. Basically we have to choose between the following six modes of operation see Fig. 4. 

---