Page 279 - Modeling of Chemical Kinetics and Reactor Design

Industrial and Laboratory Reactors 249

Figure 4-21. Continuous stirred tank reactor. (Source: V. W. Weekman,
“Laboratory Reactors and Their Limitations,” AIChEJ, Vol. 20, p. 833, 1974.
Used with permission of the AIChEJ.)

inert carrier gas or the reactant itself transports the catalyst through
the reactor. Since the catalyst passes through with the reactant, it is
necessary to achieve either rapid quenching or rapid catalyst reactant
separation. The possibility of catalyst decay selectivity disguise is
completely eliminated because the catalyst and reactants are con-
tinuously fed. For highly endothermic or exothermic reactions, iso-
thermal operation is difficult to achieve, hence, a poor-to-fair rating
in this category. For high velocities where there is little slip between
the catalyst and reactant phases, there are accurate measurements of
residence time. At lower velocities, there may be slip between the
phases that can lead to difficulties in accurately determining the
contact time. Since the transport reactors are a length of tubing, they
are easier to construct, but salt or sand baths may be required in order
to maintain isothermal operation. Additionally, the construction rating
is fair-to-good because product-catalyst separation facilities are required.

RECIRCULATING TRANSPORT REACTOR (RTR)

Adding a recirculating loop to the transport reactor, a well-mixed
condition is achieved provided the recirculation rate is large with