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3.2
Correction Factors
60 PSIG
70 PSIG
80 PSIG
90 PSIG
100 PSIG
110 PSIG
120 PSIG
130 PSIG
140 PSIG
150 PSIG
How to Determine Dryer Capacity at Operating Conditions:
ADJUSTED CAPACITY =
Standard Flow Rate x Correction Factor
Example:
Dryer Model:
DRYPOINT® XCe 250
Standard Flow Rate:
250 scfm
Operating Conditions: 110 psig / 110 °F
ADJUSTED CAPACITY = 250 scfm x 0.92 = 230 scfm
3.3
General Function
The DRYPOINT® X heatless desiccant dyer series are fitted with two pressure vessels, positioned parallel to one another
and filled with adsorption material (⅛" activated alumina as standard). While the compressed air is dried in one tower,
the saturated desiccant is regenerated in the second. A minimal portion of the treated air is used for the regeneration
process and expelled along with the condensate, through the silencers.
The saturated inlet air is cycled through each of the two desiccant beds in an alternating sequence where one bed is on-
line at full line pressure and flow, adsorbing the water vapor. This is the drying bed.
The other bed is then considered to be in an off-line state at atmospheric pressure and is being regenerated by a
depressurized portion of the dried, treated outlet air (purge air). This is the regenerating bed.
The purge air is routed from the dry outlet air through the purge flow control valve, desiccant bed, purge exhaust valve
and finally exhausted to atmosphere through silencers to finish the regeneration process. Purge air consumption is
generally the highest cost involved with operating a heatless adsorption dryer and is non-recoverable. Therefore, the air
system where the dryer is installed must account for this usage (approximately 15% of the inlet air flow).
Just before the freshly regenerated bed is brought to an on-line state to become the drying bed, it is slowly pressurized
from atmospheric pressure up to line pressure. This is the re-pressurization step that prevents desiccant bed fluidization
(bed lifting) and dusting. The desiccant beds will now switch functions where the fresh desiccant bed is now drying and
the saturated bed is now regenerating.
This cycle will continue automatically unless the dryer is shut down.
All desiccant dryers work using the principle of adsorption, which is the process by which water vapor is removed from
the compressed air being dried. All desiccant material types are adversely affected by contaminants including oil,
DRYPOINT® XC Series Heatless Regenerated Dryers: IOM10003
Correction Factors
≤ 90°F
95°F
100°F
0.70
0.68
0.65
0.79
0.77
0.74
0.88
0.85
0.82
0.97
0.95
0.91
1.07
1.04
1.00
1.17
1.13
1.09
1.25
1.22
1.17
1.31
1.27
1.22
1.34
1.30
1.25
1.39
1.35
1.30
105°F
110°F
115°F
0.60
0.55
0.50
0.68
0.62
0.57
0.75
0.69
0.63
0.84
0.76
0.70
0.92
0.84
0.77
1.00
0.92
0.84
1.08
0.98
0.90
1.12
1.02
0.94
1.15
1.05
0.96
1.20
1.09
1.00
How to select the dryer for actual conditions:
ADJUSTED CAPACITY =
System Flow Rate ÷ Correction Factor
Example:
System Flow Rate:
300 scfm
Operating Conditions: 130 psig / 100 °F
ADJUSTED CAPACITY = 300 scfm ÷ 1.22 = 246 scfm
Select Dryer Model:
DRYPOINT® XCe 250
(Rev.I)
120°F
0.46
0.52
0.57
0.64
0.70
0.76
0.82
0.84
0.88
0.91
8
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