VPS Vacuum Purge Heatless Dryer

The VAPS VPS Vacuum Heatless Pressure Swing Dryer for Compressed Air Dryer offers the lowest capital cost and lower long term operating costs compared to conventional heatless dryer and heat regenerative dryer. The VPS Vacuum dryers offer the highest reliability solutions for low dew point compressed air.

These dryers are made simple to install, operate and able to provide consistent  low pressure dew point of up to -40°C and -70°C

How the VPS Vacuum Heatless Dryer work
Saturated compressed air enters the system through the Pre- Filter, where liquid water and oil contaminants are removed. The air then enters the dryer through the right chamber.

Moisture is adsorbed by the desiccant as the air flows through the chamber. Adsorption is an exothermic (heat releasing) process, and as it progresses through the chamber, heat of adsorption is released. This heat later contributes to regeneration. Dry compressed air exits at the outlet valve, and then through an After Filter, where any desiccant dust being carried by the air will be removed. The clean and dry air then
proceeds downstream to the plant.

While the right chamber is in the drying cycle, the off stream left chamber is depressurized to atmosphere. A portion of the -40°C/-70°C PDP dry air is metered through the purge adjusting valve, expanded to vacuum pressure (further reducing the dew point to -90°C or more), and is then passed through the wet desiccant bed counter-current to the drying flow. This extremely dry purge air, in conjunction with the heat of adsorption stored in the bed during the drying cycle, regenerates the desiccant
bed. The purge air is then exhausted through the purge exhaust valve and then a silencer to the atmosphere. Prior to switching, the newly regenerated left chamber is re-pressurized by closing the purge outlet valve

The dryer operates on a 4 to 10 minute automatic cycle, depending on the settings
5 minutes drying and 5 minutes regenerating.

The dryer’s fail-safe design provides continued supply of dry air for
hours even if the control system’s power supply is lost or interrupted.


Advantages :

  • Lower Operating and Maintenance Costs
  • Low Purge Loss of only 2.6%
  • Lower Energy Consumption
  • Better Safety – No Hot surfaces
  • Easier and Faster Maintenance
  • No Need to Heat and Cool Down Desiccant
  • Longer Desiccant Life with lower dusting
  • Able to switch back from Vacuum Regeneration to Normal Pressure Swing function
  • Very Reliable and Uncomplicated Operations
  • Less Moving Parts and thus less chances for breakdowns
  • Lower Capital Investment

With conventional dryers, the dry air is decompressed from about 8
bar(a) to 1 bar(a), and this reduces the dew point from -40°C to about -70°C. The decompression ratio is about 7 times. While in Vacuum Purge Dryer the dry air is decompressed from about 8 bar(a) to vacuum conditions, and this reduces the dew point further from -40°C to -90°C, which is even drier. The decompression ratio here is higher than 7 times.

Therefore to achieve such a high ratio, a vacuum pump is installed at the outlet to create an artificial lower pressure ambient and a series of valves that controls the purging of the air.

The Energy created by the Vacuum Heatless Pressure Swing Dryer is
equivalent to dryers that heats up the desiccant and cool it down again, but without the energy/heat losses and re-cooling of the desiccant.


All VPS Vacuum Heatless dryers comes with a back up system to revert the dryer back to normal pressure swing with 15% purge loss function, in case the vacuum pump needs servicing.

The VPS Vacuum Heatless dryer has many advantages over conventional Pressure Swing and Heat Regenerative dryer.
The following are the comparison.