ZEKS Eclipse 1000ZPA, Техническое руководство, Страница: 7 / 31

ZEKS Eclipse ZPA 90-5000 Desiccant Dryers
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6.5 TOWER REPRESSURIZATION
Upon completion of tower regeneration, and prior to the
Inlet Flow Valves changing position to switch towers, the
regenerated tower must be repressurized.
Repressurization is accomplished when the appropriate
Purge Valve closes. Closing the Purge Valve allows the
regeneration air to begin to pressurize the tower. In ad-
dition to the regeneration air, the Repressurization Valve,
(standard on -80°F and -100°F dew point and high pres-
sure dryers; optional on -40°F dew point dryers) opens al-
lowing some additional air from the outlet of the dryer to
ensure adequate pressurization.
6.6 VALVES
Solenoid valves are used to actuate the Flow Valves,
Purge Valves and the optional Repressurization Valve on
Eclipse Heatless Dryers. The Inlet Flow Valves and op-
tional Repressurization Valve are normally open valves,
while the Purge Valves are connected as normally closed
valves. This arrangement permits air to fl ow through the
dryer during periods of loss of power.
Outlet Check Valves are single direction check valves that
will allow fl ow in the direction shown on the P&ID, but not
allow fl ow in the opposite direction.
6.7 TIMING SEQUENCE
All timing functions on NEMA 1 dryers are performed by
the Solid State Timer (SST) and on NEMA 4 dryers by
ZEKS DPC™ Controller. Regardless of controller, the tim-
ing of ZEKS -40°F, -80°F and -100°F dryers is as follows:
6.7.1 TIMING CYCLE FOR -40°F DEW POINT DRYERS
The standard timing cycle for -40°F operation switch-
es the Inlet Flow Valve position every fi ve minutes
which alternates the drying tower. At the same time
as a tower Inlet Valve opens, the appropriate tower
Purge Valve opens to depressurize the regenerating
tower. Tower regeneration occurs for 4 minutes and
15 seconds, at which time the Purge Valve closes to
initiate repressurization.
6.7.2 TIMING CYCLE FOR -80°F AND -100°F DEW
POINT DRYERS
The standard timing cycle for both -80°F and -100°F
operation switches the Inlet Flow Valve position ev-
ery 2 minutes which alternates the drying tower. At
the same time a tower Inlet Valve opens, the appro-
priate tower Purge Valve opens to depressurize the
regenerating tower. Tower regeneration occurs for
1 minute and 50 seconds, at which time the Purge
Valve closes to initiate repressurization. The Re-
pressurization Valve opens to assist tower repres-
surization for the last 10 seconds prior to Inlet Flow
Valve switching.
6.0 PRINCIPLES OF OPERATION
!
NOTICE
Failure to re-pressurize prior to tower switchover will re-
sult in shocking the desiccant material and cause pre-
mature desiccant dusting.
Refer to Appendix A6,
PRINCIPLES OF OPERATION for dryers equipped
with the optional NEMA 4/DPC Package.