A compressed air dryer is used for removing water vapour from compressed air. Compressed air dryers are commonly found in a wide range of industrial and commercial facilities.
The process of air compression concentrates atmospheric contaminants, including water vapour. This raises the dew point of the compressed air relative to free atmospheric air and leads to condensation within pipes as the compressed air cools downstream of the compressor.
Excessive water in compressed air, in either the liquid or vapour phase, can cause a variety of operational problems for users of compressed air. These include freezing of outdoor air lines, corrosion in piping and equipment, malfunctioning of pneumatic process control instruments, fouling of processes and products, and more.
The performance of a deliquescent dryer, as measured by outlet dew point, is highly dependent on the temperature of the air or gas being processed, with cooler temperatures resulting in better performance.
There are various types of compressed air dryers. Their performance characteristics are typically defined by the dew point.
Dew point suppression is not a feature of refrigerated dryers, as they chill the incoming air to a fixed temperature, usually 35 °F. So a lower dew point challenge will not yield a dew point lower than 35 °F.
Regenerative desiccant dryers, often called “regens” or “twin tower” dryers
Refrigerated dryers
Deliquescent dryers
Membrane dryers
A regenerative desiccant dryer typically delivers a dew point of between −40 °F (−40 °C) and −100 °F (−73 °C)
A refrigerated dryer delivers a dew point not lower than approximately 35 °F (2 °C)
A deliquescent dryer delivers a dew point suppression that fluctuates with air temperature. Typically this suppression is 20 °F (11 °C) below the compressed air temperature.
Drying air for use in commercial or industrial processes that demand dry air:
Telecomm industry (pressurizes its underground cables to repel moisture and avoid shorts)
Pneumatic tools
Textile manufacturing
Pneumatic control systems
Feed air for zeolite type oxygen and nitrogen generators
Dental office air
Truck and train air brake systems