A common inefficiency in process plants is the cooling of streams that
should not be cooled. A petrochemical facility installed an air cooler on the feed line of a
distillation column (Figure 25.3) to prevent the condenser from being overloaded during
certain abnormal operating conditions [5]. Although the air cooler was designed for use
only during abnormal conditions, it became an accepted practice to run it continuously
during normal operations. Removing heat from the feed during normal conditions required
the reboiler to work harder, thereby increasing the steam load.