Multiphase Bioreactor Design

(43)

Ideal reactors

Basically there are three types of ideal reactors:

(a) the batch stirred tank reactor (BSTR);
(b) the plug flow reactor (PFR);
(c) the continuous stirred tank reactor (CSTR).

The reactor performance of these three main types of reactors, when the reactions are
kinetically controlled, are described in the following sections.

Batch stirred tank reactors

A batch reactor has neither feed nor effluent streams. The substrate on the biocatalyst is
introduced to start the reaction, and both the product concentration, P, and the conversion
degree, X=[(S 0 —S)/S 0 ], increase within time, t, while the substrate concentration, S,
decreases. Referring to the general balance equation (42), for a constant volume batch
reactor, volume V, the balance becomes:

(44)

For heterogeneous catalysis, the reaction takes place at the surface of the solid catalyst
and:

(45)

where rw is the reaction rate per weight unit of the solid and W is the solid weight. For
immobilised biocatalyst systems:

(46)

and:

(47)

The following equation describes the reactor performance of an immobilised enzyme
batch reactor:

(48)

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