Page 213 - Design of Simple and Robust Process Plants

198 Chapter 5 Process Simplification and Intensification Techniques
Table 5.8. Summary of heterogeneous reactor systems G/S and L/S, G/L, G/L/S the ranking of
reactor selection in order of increasing complexity.

G/S and G/L G/L G/L G/L/S
Liquid phase Interfacial controlled
controlled
1) Adiabatic packed 1) Bubble column 1) Spray column 1) Trickle flow packed
bed bed
2) Packed bed(s) with 2) CSTR, jet mixer 2) Packed column 2) Spray column packed
cooling bed
a) recycle
b) cold injection
c) inter-stage cooling
3) Fluidized bed 3) CSTR with agitator 3) Packed bubble/
multi-stage, column
4) Multi-stage fluidized 4) Multi-tray bubble 4) Slurry
beds column
5) Multi-tubular reactor 5) Tray column 5) Multi tubular
6) Membrane
separation

The general rules for the design of reactor systems to obtain less complex systems
are:
1. Design for homogeneous liquid phase reactor systems, the liquid phase is
preferred above the gas phase.
2. Heterogeneous reactor systems are preferably converted to homogeneous
systems.
3. Integrate reaction with other process functions like: other reactions, distilla-
tion, extrusion, heat exchange (reverse flow reactor).
4. Reactor systems are preferably operated adiabatic (no heat transfer provi-
sions), with larger solid particles (easily captured/separated), flow distribu-
tion/mixing by static devices.
The ranked reactor types with an increase in complexity did not take into account
any thermodynamic or reaction kinetics information which might force the designer
from an economical perspective to a more complex reactor design. The results of
the reactor discussion are summarized in Tables 5.7 and 5.8.

5.7.2
Distillation and Absorption

Distillation and absorption is one of the oldest ± and certainly one of the most
applied ± separation techniques used for homogeneous mixtures. The advantage is
that it can easily be designed based on vapor liquid equilibrium data that are readily
available in public databanks, or can be determined at laboratory scale at relative low