COLD REGENERATED ADSORPTION DRYERS

Cold regenerated adsorption dryers designed and manufactured by Airpol ensure continuous delivery of high quality compressed air, free from moisture and – to a great extent – from solid particles and oil. Compressed air treated with Airpol adsorption dryers reaches the pressure dew point temperature at: (-20ºC NDA series), (-40ºC OAD series), (-70ºC ADU series).

The automatic operation of two columns filled with a bed of activated aluminium oxide sorbent, in which adsorption and regeneration alternate, allows for a continuous supply of dried air. While one column is subjected to a phase of adsorption (absorption of moisture from the compressed air), the other column is subjected to bed regeneration (drying of the adsorbent) with approx. 15 % of the dried air being expanded. The flow of the expanded air is opposite to that of the compressed air. This results in the adsorption of water particles from the bed and their subsequent removal to the environment.

The length and frequency of column cycles, and therefore the nature of the unit’s operation, are determined by the control system used in the particular dryer:
Energy-efficient dew point control system in adsorption dryers NDA SP, OAD SP, ADU SP

The control is based on the measurement of the pressure dew point at the compressed air outlet from the dryer. The measurement is performed through a mounted dew point transducer which continuously measures the air humidity. The frequency and duration of the dryer’s operating cycles depend on the results of the measurement of the air leaving the dryer. As a result, losses of dried air are eliminated and the whole adsorption cycle is adjusted to changing operating conditions. This is the most cost-effective control system that minimises the running costs of the unit, ensuring a return on investment within a few months.

Time control in NDA, OAD, ADU DRYERS
The controller regulates the operation of operating valves and the regeneration of adsorbers at programmed intervals. The adsorption and regeneration phases occur simultaneously, following the principle of alternating cycles, exactly every 5 minutes

Airpol’s cold regenerated adsorption dryers are distinguished by:

• High quality of compressed air with very low relative humidity, which effectively prevents condensation of water.
• Small drops in compressed air pressure thanks to application of large capacity tanks filled with adsorbent as well as supply and receiving manifolds with large diameter. This results in low compressed air velocity and therefore low pressure drop.
• Ready for continuous operation to ensure uninterrupted supply of dry compressed air.
• Simple design and easy to operate.
• High energy efficiency of dryers equipped with a dew point temperature sensor, which allows to automatically adjust the frequency of dryer cycles to the actual conditions and thus reduce the consumption of compressed air for bed regeneration.