FORCED DRAFT UNIT
Advantages
 Better accessibility
y of mechanical components
p




for maintenance
Slightly lower horsepower since fan is in cold
air.
i (Horsepower
(H
varies
i directly
di
l as the
h absolute
b l
temperature)
Less Vibration because of isolated support for
mechanical equipment
Bundle are easy to remove for major repair
lower capital cost.
Tube Bundle
Fan Drive Details
• Direct Drive
• Forced
Forced-Draft
Draft
Belt Drive
Typical Extended Surface Tubes
Which standards are used for AirAir
Cooled Exchangers?
 First, almost all air coolers are built to Sect. VIII,
Division 1 of the ASME Code, since they are
pressure vessels
 API661 standard for air-cooled heat exchangers
 TEMA (T
(Tubular
b l E
Exchangers
h
M
Manufacturing
f t i
Association)

HTRI (Heat Transfer Research Institute)
Air Coolers
Temperature Control
The combination of adjustable
shutters with variable speed
p
drive or with controllable fan
pitch is frequently used for
close fluid temp control.
Thi system is
This
i particularly
i l l
useful during start-up or shutdown where fluids are subject
to freezing in cold ambient
temps.
It is well adapted to fluid temp
control under high wind and
freezing conditions.