5 the closed loop drying system, 6 what is desiccant, 7 the process/regeneration cycle – AEC WD 350 through WD3000 Dehumidifying Dryers User Manual
Page 14
350-2100 cfm Dryers
Chapter 2: Functional Description
13 of 58
2-5 The Closed Loop Drying System
ACS dryers force hot, dry air through the resin in the drying hopper, where the air picks up
moisture from the material and is drawn back to the dryer.
In the dryer, moisture is stripped from the air by a desiccant bed. The dried process air is then
re-heated and delivered back into the drying hopper to dry material again.
This system is a "closed loop", because ambient (outside) air is never introduced into the
process air. The closed loop system is used by ACS because the process air is typically much
drier than ambient air, even after carrying moisture out of the plastic resin. Recycling process
air maintains drying efficiency at a consistently high level.
Figure 1: WD/SDA/CDA 350-2100 Dryer Specifications
Model
Number
Amp
Draw
Dimensions
(Inches)
Hose
Connection
(Inches)
Shipping
Weight
Process
Blower
Regen
Blower
Desiccant
Lbs./Bed
460-3-60
L
W
H
I.D. Lbs. Hp.
Hp.
Large
Small
350
56
56
73 4 1000 5 ½ 30 76
350-RT
56
56
73 4 1000 5 ½ 30 76
425
61
52
82
5
1100
7½
½
30
90
425-RT
61
52
82
5
1100
7½
½
30
90
500
63
66
94
5
1200
7½
¾
40
100
500-RT
63
66
94
5
1200
7½
¾
40
100
600
58
56
88
6
1450
10
¾
40
120
600-RT
58
56
88
6
1450
10
¾
40
120
700
59
66
93
6
1600
10
¾
40
135
700-RT
59
66
93
6
1600
10
¾
40
135
850 103
88
84
90
8
3
¾
120
120
850-RT 141
88
84
90
8 3
¾
120
120
1000 113
88
84
90
8
7½
¾
120
130
1000-RT 146
88
84
90 8
7½ ¾ 120
130
1250 138
88
84
90
8
7½
¾
120
180
1250-RT 194
88
84
90 8
7½ ¾ 120
180
1500 156
94
100
90
8
7½
¾
120
240
1500-RT 213
94
100
90 8
7½ ¾ 120
240
1800 179
94
100
90
8
10
¾
120
310
1800-RT 235
94
100
90 8
10 ¾ 120
310
2100 203
94
100
98
10
15
¾
120
360
2100-RT 278
94
100
98
10
15 ¾ 120
360
2-6 What
is
Desiccant?
Desiccant is a material which attracts and holds (absorbs) water from the air. The desiccant
ACS dryers use is a synthetic crystalline metal aluminosilicate that is blended with a clay
binder and formed into beads.
Absorbed water is driven from saturated desiccant by heating it to a high temperature
(reducing the desiccant's capacity to hold water) and forcing air through it. This moisture
removal process is called "regeneration".
2-7 The Process/Regeneration Cycle
ACS dryers have two desiccant beds. While one bed is on-line in the process air loop, the
other is off-line being regenerated.