Page 257 - Modeling of Chemical Kinetics and Reactor Design

Industrial and Laboratory Reactors 227

Figure 4-5. A battery of continuous flow stirred tank reactors.

with time. It is approximated that a steady state operation is reached
when about five to ten times the reactor volume of the reaction mixture
has passed through the reactor. In the continuously flow stirred tank
reactor, the reaction takes place at the temperature and the degree of
conversion of the outlet stream. This gives the reactor its characteristic
features from either the batch or semi-batch reactor.
Figure 4-6 is a variation of the continuous homogeneous reactor
(baffled tank) in which backmixing has a considerable effect. The
advantage of this type of reactor is its low cost per unit volume. It is
often used when a long holding time would require a tubular reactor
that is too long or too expensive. Agitation is not required and a high
degree of backmixing is not harmful to the yield.

CONTINUOUS ISOTHERMAL PLUG
FLOW TUBULAR REACTOR

The plug flow tubular reactor is a heat exchanger where the reaction
occurs in the tubes. Construction is often varied. For example, the
reactor may consist of a tube placed in a bath, a tube in a jacket, or
a number of tubes immensed in a heat transfer medium for the reactor