Page 217 - Design of Simple and Robust Process Plants

202 Chapter 5 Process Simplification and Intensification Techniques
2. A distillation column with a side stream as a third product stream.
3. A distillation column with a purified side stream with either a side stripper
or a dephlegmator or rectifier ± installation of a side stripper or rectifier with-
in the column is a prefered option (Figures 5.4 and 5.5).
4. A divided wall column with a purified side stream.
5. Direct coupled column (see Figures 5.10 through 5.13).
6. A sequence of two distillation columns.
The above alternatives for one-, two-, and three-component separation are summar-
ized in Table 5.2.
Four-component separations are listed in order of increasing complexity are
shown in Figures 5.38 and 5.39:
1. A distillation column with lights removed at the overhead condenser, liquid
top product, side product stream, bottom stream. (lights might be purified
further with a dephlegmator at the top).
2. A distillation column with lights removed at the overhead condenser, liquid
top product, purified side product stream, bottom stream. (purification of
side draw with either a side stripper or a dephlegmator).
3. A divided wall column (DWC)with lights removed at the overhead, liquid top
product removal, side product streams, bottom stream.
4. A divided wall column with two side streams as third and fourth streams.
5. A divided wall column followed by a conventional distillation.

DISTILLATION WITH FOUR COMPONENTS
(1)
LIGHTS
(2)
(3)
F
HEAT
(4)
(1)
LIGHTS
(2) (1)
(3) (2)
F F
(3)
HEAT
HEAT
(4) (4)

Fig. 5.38. Four component separation with; side draws or DWC