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3.2
Correction Factors
Sizing must be done by a product specialist, please consult your BEKO Technologies representative for details and sizing
assistance.
3.3
General Function
The DRYPOINT® XF heated desiccant dryer 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 Vessel,
the saturated desiccant is regenerated in the second.
The saturated inlet air is cycled through each of the two desiccant beds in an alternating sequence. One bed is on-line at
full line pressure and air flows upward through the vessel where the desiccant extracts and retains water vapor, thereby
lowering the dew point before exiting the vessel to the air distribution system. This is the drying bed.
The other bed is then considered to be in an off-line state and is being regenerated by heat from a blower that forces air
across an in line heater into the regeneration Vessel under atmospheric pressure. This heated dry air flows through the
Vessel, desorbs water from the moisture laden desiccant, before exiting the bottom of the Vessel. This moist air passes
though exhaust valve and is vented to open atmosphere. Because this method of regeneration uses heat, the desiccant
needs to be cooled before it can be used again as the drying bed.
Cooling is done in 2 phases. In phase 1, while the heater turns off (after heat regeneration is complete), the blower
remains on and cools the heater down to a preset temperature. After the temperature is reached, the purge control
valve opens and desiccant bed cooling takes place during phase 2. The purge air also passes the exhaust valves and is
vented to open atmosphere.
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.
Before desiccant bed switch over, the dryer will parallel flow through both vessels. This helps to mitigate temperature
and/or dew point spikes that can occur during a direct Vessel switchover.
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 oil, aerosols, dirt, rust, scale and
liquid water. If contaminated, the desiccant material will lose its adsorption proprieties. Moreover during operation, the
desiccant releases solid particles as fine powder that are abrasive and can be extremely damaging to downstream
components and users.
For this reason, the dryer must be equipped with two high-efficiency CLEARPOINT® filters:
0.01 micron filtration grade coalescing pre-filter with differential pressure gauge and either a float drain or
BEKOMAT®
1.0 micron filtration grade particulate post-filter (differential gauge optional) and with a manual drain.
DRYPOINT XFi 1000 manual_revA EN
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