UFC 3-240-13FN
25 May 2005
Figure 4-4. Cooling Tower Water System
(E)
Drift (B)
Warm Air
Blowdown
(B)
Fan
Fan Deck
Stack
Louver
Process
to be
Fill
Cooled
Cool Air
Makeup
System
(M)
Leaks
(B)
Air Gap
Basin
Backflow
Prevention
Circulating Pump
4-1.3 Types of Cooling Towers. Types of cooling towers include natural
draft , induced draft, and forced draft.
4-1.3.1
Natural-Draft Towers. In natural-draft towers, airflow through the tower is
achieved naturally (i.e., without any mechanical means such as fans). Air flows across
the falling water and up through the cooling tower as a result of the differential density
between the lighter, heated and humidified, air within the tower and the cooler and dryer
outside air. Fitting the tower with spray nozzles, which create more mixing of air and
water droplets and improve the evaporation efficiency, produces increased water-
cooling rates. Large utility power plants use these large natural-draft cooling towers,
which are called hyperbolic cooling towers due to their hyperbolic shape (see Figure 4-
5).
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