AEC AP Series Large Dehumidifying Dryer - Manual (Page 16)

Large Dehumidifying Dryers Functional Description 15
Sequence shutdown switch
; NFPA86, UL, AGA & CGA machinery electrical standards (Gas Dryers)
; Available supply voltages of 208, 230, 460, 575/3/60 and 400/3/60
2-4 Options
Dewpoint Extend
The Dewpoint Extend option measures the temperature of the moist air as it is bled to the
atmosphere after regeneration. After a period of time, the bleed temperature will rise. This
condition, called "bed breakthrough" indicates that the bed is dry. At bed breakthrough, the
bleed air temperature peaks between 350°F and 400°F.
The regeneration heaters turn off automatically on bed breakthrough for additional energy
savings. A 550°F regeneration temperature will dry the desiccant beds sufficiently to produce
process air dewpoint of -40°F. In a properly sized system, this ultra-low humidity level will
be more than adequate to dry plastics to as little as .003% moisture.
Closed-Loop Regeneration
An optional regeneration closed-loop valve and heat exchanger can be used to close the
regeneration loop during the cooling portion of the regeneration cycle. If this option is
enabled on the dryer, air will be bled to the atmosphere until the heating portion of the
regeneration cycle is finished. Then, the regeneration closed loop valve will direct air through
a water-cooled heat exchanger and back into the regeneration loop (see Figure 2).
Figure 2: Closed Loop Regeneration
AD600-AD1500
Dryer Flow Schematic
Regeneration Closed Loop
Cooling is Activated
Regeneration
Filter
Optional
Regeneration
Closed Loop
Cooler
Regeneration
Blower
Optional
Regeneration
Closed Loop
Valve
Regenerarion
Exhaust
Left Desiccant
Regeneration
Heaters
Dryer Valve
AD600-AD1500
Dryer Flow Schematic
Regeneration Heating is
Activated
Regeneration
Filter
Optional
Regeneration
Closed Loop
Cooler
Regeneration
Blower
Optional
Regeneration
Closed Loop
Valve
Regeneration
Exhaust
Left Desiccant
Regeneration
Heaters
Dryer Valve