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1.0 DESCRIPTION
A. Function
Refrigerated type compressed air dryers reduce the
moisture content in compressed air by lowering the
air temperature causing water vapor to condense
into a liquid. The liquid is then separated from the air
stream and discharged to drain. As long as the
temperature of the compressed air, as it travels
through a plant's air system, does not fall below the
temperature to which it was chilled in the dryer
(referred to as dewpoint temperature), no more
water vapor will condense into troublesome liquid. In
addition, the air is filtered of all solid particles three
microns and larger. Clean, dry compressed air leaving
the dryer minimizes maintenance and repair of
pneumatic distribution, instrument and control, and
actuation devices, reduces product contamination,
and increases productivity.
FLOW SCHEMATIC
F
E
D
F
E
C
B
A
H
G
Air Side
A.
B.
C.
D.
E.
F.
G.
H.
7
F
E
8
9
CRANKCASE HEATER
Air inlet
Air-to-air heat exchanger
Air-to-refrigerant heat exchanger
(refrigeration evaporator)
Moisture separator
Automatic condensate drains
Drain service valve
Air outlet
Pressure Gauge
B. Operation
Compressed air, saturated with water vapor, enters
the dryer and is precooled by the outgoinq refriger-
ated air in an air-to-air heat exchanger. Precooling
removes some of the heat load from the incoming
air allowing the use of a more efficient refrigeration
condensing section. The precooled air then enters
an air-to-refrigerant heat exchanger (refrigeration
evaporator) where it is cooled to a preset level by
giving up heat to the refrigeration system. As the air
cools, water vapor condenses into liquid droplets
which are separated out of the air stream by a
separator. Liquid condensate is discharged to drain
by three automatic condensate drains.
The cold air then exits after it has passed through
the other side of the air-to-air heat exchanger
where it is warmed by the incoming hot air. This
reheating increases the air's effective volume
(enabling it to do more work) and prevents pipe
sweating downstream.
5
6
5
13
12
11
14
1
Refrigeration System
1.
Refrigeration compressor
2.
Water-cooled condenser with built in
receiver
3.
Liquid line shut-off valve
4.
Filter/dryer
5.
Sight glass/liquid moisture indicator
6.
Thermostatic expansion valve
7.
Refrigeration evaporator
(air-to-refrigerant heat exchanger)
8.
Accumulator
9.
Suction line filter
10. By-pass system manual valve
11. By-pass system strainer
12. Hot gas by-pass valve
13. Desuperheating valve
14. Solenoid valves for pump-down system
15. Water regulating valve
16. Water strainer
4
14
3
COOLING
WATER (OUT)
2
15 16
COOLING
WATER (IN)
10
3
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