Hot, wet air from the compressor first enters a
dehydrating the compressed air while the other
is being reactivated. A desiccant tower is normally
refrigeration section, where low temperature
removes heat from the airstream and condenses
reactivated when dry, heated air is routed through
the tower in the direction opposite to that of the
water vapor from the air. The cold, partially-dried
normal dehydration airflow. The hot air
air then flows into a desiccant section, where the
evaporates the collected moisture and carries it
desiccant absorbs additional moisture from the
air.
out of the tower to the atmosphere. The air for
the purge cycle is heated by electrical heaters.
When the tower that is reactivating has completed
the reactivation cycle, it is placed in service to
dehydrate air, and the other tower is reactivated.
WASTE-HEAT BOILER
Figure 7-28 shows a desiccant dehydrator.
Steam for ship's services is generated by three
REFRIGERATION AND DESICCANT
AIR DEHYDRATOR (TYPE III)
the ship's service gas turbine generators (SSGTGs)
as the heat source. The boilers are of the
Some installations may use a combination of
forced-recirculation, water-tube type. Rated
refrigeration and desiccant for moisture removal.
steam capacity of each boiler is 7,000 pounds
Figure 7-28.--Dehydrator (type II).
7-27