Why Heat of Compression dryers save money?

Significance of air treatment

Clean and dry compressed air is vital to power up a production environment. Compressed air typically contains moisture, aerosols and dirt particles if left untreated.

Untreated compressed air poses a substantial risk as it can damage your air system and end product.

However compressed air treatment especially removal of moisture can be quite expensive depending upon the dew point. Deeper dew point which translates to less water content can translate to high energy costs.

Types of air dryers

There are different air drying technologies, a refrigeration type drying system delivers dew point of up to +3 °C but consumes power to physically cool down compressed air while the desiccant type twin tower dryers either consume purge air 15-20% compressed air to regenerate or alternatively use heat from electrical heaters to regenerate the desiccant bed.

All the above mentioned methods of air treatment are expensive, so what is the alternative?

Heat of compression air dryers

Air compressors typically convert all the power input into heat and this heat of compression is typically wasted either in ambient air on an air cooled compressor or rejected to the cooling water in a water cooled system.

A heat of compression (HOC) dryer uses part of the heat from the compression process to regenerate the desiccant. If a very deep dew point is not mandatory for the process, HOC dryers can literally deliver treated air at almost ZERO cost.

Within the HOC air drying technology there are twin tower type dryers or single drum rotary dryers that are married to the compressor.

However a single rotary drum type heat of compression dryer offers the most energy-efficient way to produce dry air. It’s a perfect match for the oil-free screw or centrifugal compressors. The rotary drum dryers completely avoid the loss of compressed air and consume minimal amount of power to achieve very low dew points.

Working principal of the MD type heat of compression dryer is explained below:


Dessicant dryers technologies life cycle cost comparison as below:


• MD rotary drum dryer from 200 to 4000 l/s – dew points of -25°C/-13°F
• ND rotary drum dryer from 300 to 4000 l/s – dew points to -45°C/-49°F
• A variable speed drive (VSD) dryer version is available to match the lower power consumption oil-free VSD compressors

For more details on air treatment or heat of compression technology, please contact Atlas Copco.

Heat of compression desiccant dryers Heat of compression rotary drum dryers