Dual Tower Desiccant Air Dryers

Dual tower 13X Zeolite  In Air Compressor  have many names, including pressure swing, regenerative, and instrument air dryers. Both heated and heatless models are available. Despite the varied terminology, all desiccant dryers offer a continuous supply of dry compressed air by using two identical towers containing a bed of desiccant beads.

While one tower is on stream drying the compressed air, the other tower is off stream so the desiccant in that tower can be regenerated. The regeneration of the desiccant bed is accomplished by expanding some of the dried air to near atmospheric pressure and directing it across the wet desiccant bed. This swing in pressure produces expanded air, called purge air, with a very low water vapor concentration.

Imagine that the air used for the purge flow is 80°F and has a dewpoint of -40°F at 100 psig. This purge air is then expanded from 100 psig to a couple of pounds pressure, heated to a temperature of between 350-600°F, and passed counter-currently through the wet desiccant bed. The moisture-holding capability of this superheated, dry, expanded air is extremely high.

The hot air’s vapor pressure is so low in comparison to that of the desiccant that the moisture moves from the area of higher vapor pressure (the desiccant) to that of the lower vapor pressure (the hot purge air). The purge air stream then carries the water vapor out of the Zeolite 13X For Compressed Air Dryer.

Dual tower Zeolite Molecular Sieve 13X APG desiccant air dryers typically dry instrument air and process air, and is used in applications where airlines are exposed to low ambient temperatures, below 32°F, and in other critical applications. Typical dewpoints produced by these types of dryers are -40°F to -100°F, although lower dewpoints are possible.