ZEKS Eclipse 90ZPA, Техническое руководство

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ZEKS Eclipse ZPA 90-5000 Desiccant Dryers
www.zeks.com
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6.1 INTRODUCTION
As described in Section 1, water vapor is removed from
compressed air by diverting air fl ow alternately between
two towers fi lled with desiccant. While one tower process-
es the compressed air stream, adsorbing water vapor, the
opposite tower is regenerated by desorbing the water va-
por and venting it to atmosphere. Refer to the Process and
Instrumentation Diagram (P&ID) for a visual representa-
tion of the drying and regenerating cycles.
Timing of the drying and regenerating cycles is automati-
cally controlled by a Solid State Timer (SST). An optional
programmable dryer controller is available.
6.2 DRYING CYCLE
Saturated compressed air enters the dryer and is diverted
to the appropriate tower by the Inlet Flow Valves. Refer-
ring to the P&ID, the Left Inlet Flow Valve is actuated to a
closed position to prevent air fl ow from entering the regen-
erating tower. Simultaneously, the Right Inlet Flow Valve
is actuated to an open position, allowing air fl ow to the
right hand tower. During this time, the Right Tower Purge
Valve is actuated to a closed position, preventing the
compressed air from venting to atmosphere. As the com-
pressed air fl ows through the desiccant material at pres-
sure, removal of water vapor from the air stream begins
to occur through adsorption. In the adsorption process,
the desiccant material draws water vapor out of the com-
pressed air and “holds” it until the right tower drying cycle
is complete. Compressed air fl ows out of the tower for de-
livery to the process use. The Outlet Flow Check Valves
provide air fl ow diversion to the outlet air connection of the
dryer. The Right Outlet Flow Check Valve allows air fl ow
through to the outlet connection of the dryer while The Left
Outlet Flow Check Valve checks off to prevent fl ow back to
the regenerating tower.
6.3 REGENERATION CYCLE
Previously adsorbed moisture, removed from the process
stream, gets stripped or desorbed from the desiccant ma-
terial in the regeneration process. The fi rst stage of re-
generation is tower depressurization. After the Inlet Flow
Valves are switched to divert air fl ow away from the regen-
erating tower, the appropriate Purge Valve will be opened
and the tower will be depressurized. Through rapid de-
pressurization, a signifi cant portion of the previously ad-
sorbed water vapor is stripped off of the desiccant material
and exhausted to atmosphere.
The second stage of regeneration uses a portion of the
dry, compressed air, expanded to atmospheric pressure to
complete the desorption process. As shown on the P&ID,
the compressed air exits the drying tower and a portion of
the air fl ows through the Purge Adjustment Valve and the
Purge Orifi ce. Once the air has passed through the Purge
Orifi ce, it expands to atmospheric pressure and continues
the regeneration process. Desorption occurs as the desic-
cant releases water vapor into the regeneration air and is
exhausted through the Purge Muffl er.
Eclipse Heatless Dryers may be equipped with an optional
Downstream Purge feature. By adding additional check
valves to the upper manifold, a dryer equipped with the
Downstream Purge option is able to use air from a down-
stream source to purge the regenerating tower. This op-
tional feature is useful for applications with downstream
(dry) storage tanks, as pulling air from a downstream
source can minimize cycling of the air compressor.
6.4 SETTING THE REGENERATION AIR FLOW
It is necessary to manually set the purge air fl ow to achieve
proper dryer performance. Setting the purge fl ow too high
will waste compressed air and if set too low, the dryer will
not achieve proper dew point performance.
The purge adjustment manifold consists of the Purge Ad-
justment Valve, the Purge Pressure Gauge and the Purge
Orifi ce. When the left tower is the drying tower (pressur-
ized) and the right tower is depressurized (0 PSIG), man-
ually adjust the Purge Adjustment Valve until the gauge
reading on the purge pressure gauge matches the Purge
Pressure Gauge setting listed on the laminated tag affi xed
to the Orifi ce Plate Assembly.
6.0 PRINCIPLES OF OPERATION
!
NOTICE
The right tower must be the drying tower for proper
purge adjustment setting. When the left tower is the
drying tower, the Purge Adjustment Gauge will read
close to line pressure.
!
NOTICE
On dryers equipped with the optional NEMA 4/DPC™
Package, or when using the optional Moisture Load
Control feature, the purge valve MUST be set to the
factory set point to ensure proper operation of these
features. See Appendix A-6.