Page 173 - Design of Simple and Robust Process Plants

158 Chapter 5 Process Simplification and Intensification Techniques
5.3.2.4 Direct coupled distillation separations
The divided wall column is an example of a fully thermally coupled distillation. This
might also be realized in other configurations. As example, we consider an extractive
distillation column (Figure 5.10). In the top section of the column there is a specifi-
cation on heavies and solvent, and the conventional concept used two columns for
these separation. Another coupling for an extractive distillation column is a combi-
nation with the solvent stripper is pictured in Figure 5.11, (Emmrich et al. 2000. of

Uncoupled Coupled
Lights with spec. on
heavies and solvent
Solvent Lights
Solvent

Feed Feed

Heavies in Heavies in
solvent solvent
Fig. 5.10. An extractive distillation with two specifications at
the top product, heavies and solvent, uncoupled and coupled.

Lights
Cooling
Cooling Lights
Benzene
Feed
Feed Benzene

Solvent Solvent
Fig. 5.11. Conventional two columns versus a thermally cou-
pled extractive distillation (Emmrich et al., permission of Kruppe
Uhde).