Page 180 - Design of Simple and Robust Process Plants

5.4 Integration of Process Equipment 165

REACTANTS
STEAM

FEED
AIR

FUEL-GAS FLUE-GAS

STEAM

CRUDE PRODUCT

Fig. 5.20. Adiabatic bed±Heated case tubular part±Adiabatic
bed of a low capacity styrene monomer process with flue gas
heating.

Distillation always offers the opportunity to integrate adjacent equipment with or
around distillation columns (Meili, 1997):
. Reboilers for small columns; this often done using a vertical shell and tube
exchanger in the bottom of the column. For larger columns, a horizontal
tube bundle is installed in the bottom, making cleaning relatively easy.
. Overhead condenser on top of the tower with reflux collection in the top tray
(Figure 5.21). This concept is also applicable for air-coolers which are placed
vertically in a triangular configuration at the top of a column.
. Compact heat exchangers; manufacturers such as Alfa Laval promote instal-
lation of these exchangers for reboilers and overhead condensers.
. Overhead condenser integrated with vent condenser and reflux drum (Fig-
ure 5.22).
. Knock-out drum in the skirt of the tower.
. Columns on top of each other are seldom applied, and only when the avail-
able area is quite restricted. This should not be confused with coupled distil-
lation columns (see Figure 5.11) and another configuration (see Figure 5.12).
. Demister in the top of the column to avoid carry-over of liquid in high-
velocity applications.
. Settlers in reflux drums, particular applied to the separation of heteroge-
neous azeotropes.