Aircel AEHD Series / Externally Heated Regenerative Desiccant Dryer

Regenerative compressed air dryers use desiccant to adsorb water vapor from the compressed airstream. In the twin tower design one tower dries the air from the compressor while the desiccant in the other tower is being regenerated to provide continuous operation. These dryers are typically referred to as “heatless” or “heated”. Heatless dryers do not use any source of heat for regeneration other than the heat given off during the drying phase. This is known as the “Heat of Adsorption”. Heated dryers, on the other hand, utilize an external heat source for regeneration and require little or no process air.

The Aircel AEHD Series Dryers (150 - 3,000 scfm) utilize process air for regeneration of the desiccant bed similar to the heatless designs. However, this expanded process air is heated prior to entering the off-line bed, significantly reducing the required consumption and the cost of operation. Additionally process air is consumed during depressurization of the offline desiccant tower. In total these functions amount to an average process air use of 7% of the rated capacity of the dryer.


  • Removable, stainless steel desiccant bed support screens
  • Tower pressure gauges
  • ASME code desiccant towers (6” vessels and larger)
  • High temperature outlet check valves
  • Fail-safe design
  • 1-1/2” thick fiberglass insulation
  • Highly reliable programmable logic control (PLC)
  • Energy saving venturi option available on request

Filtering and drying incoming air. Hot, saturated compressed air is filtered as it passes through our 0.01 micron high-efficiency coalescing prefilter (F1, recommended option) before entering the dryer. Compressed air continues through the inlet valve (V1), is dried in the desiccant tower (T1), and exits through an outlet valve (V5) and final particulate filter (F2, recommended option), while the other desiccant tower (T2) is being regenerated.

Desiccant regenerated in T2. A portion of the dried air is diverted through purge valve (P3) at near atmospheric pressure and heated by the electric heater (or optional steam heater) to 400°F before passing through regeneration valve (V4) and into the regeneration tower (T2). The heated air removes moisture vapor from the desiccant surface.

Dryer operation is performed automatically by a programmable logic controller (PLC). The standard drying and regeneration time cycle is 8 hours. While one tower is drying incoming compressed air for 4 hours, the other tower is regenerating for 3 hours (heating time), then cooling for 50 minutes, and finally repressurizing to the line pressure for 10 minutes Filtering and drying incoming air. before switching over to the other tower. Switching from one tower to the other is performed only when both desiccant towers are at line pressure to prevent line surge and to minimize desiccant abrasion.

Model Capacity1 (scfm) Connection
(inches FNPT/ANSi)
Heater kW Full Load Amps Voltage (Standard) Dimensions (inches) Pressure max. (psig) Weight (lbs) Desiccant Both Vessels (lbs)
Height Width Depth
AEHD-150 150 1 2.5 3.2 460V/60 Hz/3Ph 75 45 30 150 810 200
AEHD-250 250 1-1/2 4.5 6.2 460V/60 Hz/3Ph 75 50 35 150 1200 400
AEHD-350 350 2 6 8.1 460V/60 Hz/3Ph 75 54 35 150 1600 500
AEHD-500 500 2 9 11.8 460V/60 Hz/3Ph 83 60 39 150 2000 700
AEHD-750 750 3 FLG 12 15.6 460V/60 Hz/3Ph 89 75 44 150 2600 960
AEHD-1000 1000 3 FLG 15 19.3 460V/60 Hz/3Ph 98 88 54 150 3500 1400
AEHD-1200 1200 3 FLG 20 25.6 460V/60 Hz/3Ph 109 96 60 150 3900 1800
AEHD-1500 1500 4 FLG 24 30.6 460V/60 Hz/3Ph 109 102 69 150 4500 2100
AEHD-2000 2000 4 FLG 30 38.2 460V/60 Hz/3Ph 115 120 69 150 5800 2800
AEHD-2500 2500 4 FLG 36 45.7 460V/60 Hz/3Ph 115 130 73 150 6600 3600
AEHD-3000 3000 6 FLG 45 57.00 460V/60 Hz/3Ph 120 140 77 150 7500 4200

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