Great Lakes Series GEHB Air Dryers use a positive displacement type blower to supply the purge air for desiccant regeneration. Atmospheric air is drawn in to the blower through an intake filter silencer. During the heating portion of the regeneration cycle, the air is heated with an external circulation heater similar to the externally heated models. Because wet gas regenerative dryers produce unstable dewpoints, this series provides a standard mode selector valve to stabilize outlet dewpoints. The modes are field selectable; Blower Purge, Blower Polishing, or Externally Heated. In the Blower Polishing mode stable low dewpoints can be maintained by using a small purge percentage of 2.5% of inlet. The GEHB Series is a heavy duty, high quality, blower purge regenerative dryer system. The system has low operating costs and requires no compressed air purge in the Blower only Mode. Water-cooled blower Aftercooler is available as an option to improve performance in the blower only mode.

Sequence of Operation

Compressed air laded with moisture vapor enters the system 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 diffuser screen, and past the outlet check-valve. A positive displacement blower moves atmospheric air in the circul-

tion heater where it is 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 atmospheric purge air to cool the bed. If the system is operating in the polishing mode the blower shuts down and the system draws dry compressed purge air for the cooling cycle. Several minutes before the cycle nears completion the purge valve closes and a solenoid repressurization valve opens allowing the regeneration vessel to equalize pressure with the on-line tower. The cycle completes after 4 hours and the inlet valve invert continuing the cycle.