Page 212 - Design of Simple and Robust Process Plants

5.7 Simplification and Ranking per Unit Operation 197
Reactor devices will always be a balance between thermodynamic equilibrium, reac-
tion kinetics, and heat and mass transfer, complemented with a desired flow pat-
tern. This must all be encapsulated in a cost-effective manner. The above-mentioned
information was provided to help the designer stay on a simple track. It was not the
intention to cover all reactor types, but more to install a thought process that might
not be encountered in design manuals. The results are summarized in Tables 5.7
and 5.8.

Summary
As there is a large differentiation in types of reactors they have to be divided into
categories. The most practical and accepted method is by differentiation of the
phases involved. The first split is made between homogeneous and heterogeneous
systems while heterogeneous reactor systems are further split in: L/L, G/L, L/S,
G/L, G/L/S.
The selection of preferable reactor types was made in a generic way independent
from thermodynamics or kinetics consideration which always will put constraints
on the reactor system design as does the availability of the specific reactor technol-
ogy.

Table 5.7. Summary of reactor systems, homogeneous G and L and heterogeneous L/L, the ran-
king of reactor selection in order of increasing complexity.

Homogeneous Options for cooling Options for mixing Heterogeneous
G and L L/L

1) Adiabatic tube 1) Adiabatic tube
a) Process flow, up Static mixers /
vortex mixers
b) Solvent/heat carrier,
up
c) Inlet temperature
down
d) Cold feed injection
2) Tube(s) with heat
exchange
a) Jacket pipe
b) Staged inter-cooled
c) Shell and tube
3) CSTR 2) CSTRs in series
a)Process flow, up a) Jet mixer with feed/
agitator
b) Reflux condenser b) Jet mixer with feed/
agitator
c) Spiral cooling c) Agitator
d) Jacket cooling c) Agitator
e) External cooling c) Jet mixer with recycle