External Heated Regenerative Air Dryers incorporate a low watt densi-ty, external cir-culation heater in the purge line to heat the purge air. Heating the air increases its ability to carry away adsorbed moisture, reducing com-pressed air consumption during regeneration. Great Lakes Series GEH Air Dryers automatically deliver a standard -40° F pressure dewpoint. The model series can optionally attain dewpoint’s as low as -100°F. The system is easily maintainable and is extremely reliable in both dewpoint suppression and mechanical reliability.

The GEH Series is most economical in systems with medi-um to high air volume, because of low operating costs and moderate original equipment purchase. The system requires only a 7% purge rate half of a Heatless dryer.

Sequence of Operation

Compressed air laded with moisture vapor enters the sys-tem through the right inlet valve and proceeds to enter the desiccant bed through the stainless steel diffuser screen. The air flows up from the bottom of the tank to the top allowing separated and condensed liquid to remain at the bottom of the vessel not contaminating the rest of the desiccant. The dehydrated compressed air then exits the right vessel through the top stainless steel dif-fuser screen, and past the outlet check-valve. A percent-age of the dry air is metered, heated and directed to the left desiccant bed for regeneration. The hot adsorbent

purge air enters the desiccant bed from the top and flows down heating the desiccant bed and collecting moisture from the desiccant. The now moisture laden purge air exits the system through the purge valve and muffler. After 2.5 hours the purge heater cycles off allowing the unheated purge air to cool the bed. Several minutes before the cycle nears completion the purge valve closes and allows the regener-ation vessel to equalize pressure with the on-line tower. The cycle completes after 4 hours and the inlet valves invert continuing the cycle. the purge valve and muffler. After 2.5 hours, the purge heater cycles off allowing the un-heated atmospheric purge air toe cool the bed. Several minutes before the cycle nears completion the purge valve closes and a solenoid repressurization valve opens allowing the regenerativion vessel to equalize pressure with the on-line tower. The cycle completes after 4 hours and the inlet valves invert continuing the cycle.