The Right Regenerative Air Dryer for Your Compressed Air System

The presence of water in compressed air systems can cause major problems. Consider this: a typical 100 HP compressed air system at common ambient conditions generates as much as 40 gallons of water in a 24-hour period. As a result, industries lose millions of dollars each year from lost production, increased maintenance costs, and a reduction in quality. The solution, quite often, is to install a regenerative air dryer or other drying equipment.

While that may seem simple, the key is choosing the appropriate type of drying equipment. In this post, we will focus on selecting the right regenerative air dryer, but remember that this is not the only type of drying equipment.

Initially, facility managers need to understand what degree of drying is needed. This can be determined by consulting with compressed air system experts. After all, drying compressed air beyond the level necessary results in higher operational costs.

What Industries Use Regenerative Dryers?

Many industries need very dry compressed air with pressure dew points approaching -40 pdp, even as low as -100 pdp. A few of these industries include medical, aerospace, food and beverage, and semiconductor. This is far beyond the range of refrigerated air dryer capabilities and can only be provided by using some type of regenerative air drying technology.

Types of Regenerative Air Dryers

While there are variations within the family of regenerative air dryers, the five basic regenerative air dryer types include pressure swing, exhaust purge, blower purge, vacuum assist, and heat of compression. Below you can find information on all of these dryer types.

Pressure Swing Regenerative Air Dryer

Regenerative air dryers operate without a heat source and achieve low dew points by using dry purge air from the process.

Advantages:

  • Low initial cost
  • Ability to achieve low dew points (-40 pdp or lower)
  • Lower maintenance requirements
  • Simplicity of design

Disadvantages:

  • Consumes process air for regeneration
  • (15%) Higher cost of operation in large sizes
  • Shorter cycle time

Exhaust Purge (Externally/Internally Heated)

Regenerative air dryers utilize both a heat source and dry purge air from the process.

Advantages

  • Lower cost of operation in large sizes
  • Ability to achieve low dew points (-40 pdp or lower)
  • Longer cycle time

Disadvantages

  • Moderate initial cost
  • Moderate maintenance costs
  • Consumes process air for regeneration
  • Consumes some electrical costs

Blower Purge

Blower purge dryers utilize a heat source, blower and dry purge air from the process.

Advantages

  • Lower cost of operation in large sizes
  • Ability to achieve low dew points (-40 pdp or lower)
  • Longer cycle time
  • Consumes a small amount of process air for regeneration (0% – 2% on average)

Disadvantages.

  • Higher initial cost
  • Moderate maintenance costs
  • Possible dew point or temperature spikes at switchover (when process purge air is eliminated)
  • 7% process air purge consumption when regenerating

Vacuum Assist

Regenerative air dryers utilize a heat source and vacuum blower.

Advantages

  • Lower cost of operation in large sizes
  • Longer cycle time
  • Eliminates all process air purge use
  • No dew point or temperature spikes at switchover
  • Multiple compressor capability

Disadvantages

  • Higher initial cost
  • Moderate maintenance costs

Heat of Compression

Heat of compression regenerative air dryers utilize heat from the air compressor.

Advantages

  • Lower cost of operation in large sizes
  • Ability to achieve moderate dew points (+10 to -20 pdp)
  • Eliminates all dry purge use
  • No dew point or temperature spikes at switchover

Disadvantages

  • Higher initial cost
  • Dew points vary with operating conditions
  • Moderate maintenance costs
  • Must be matched to a single compressor
  • Can only be used on oil-free air compressors

Contact a Specialist

Due to the many variations of these types of regenerative air dryers, as well as in their applications, more detailed information may be needed. For more information and assistance in making the right selection for your company, please contact us at 800.582.5162 or email.

Adapted From 2009 Satellite Newsletter Written By Ron Nordby

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