Different Methods for Drying Compressed Air

Moisture in atmospheric air is present in the form of water vapour and depends on the air's temperature and pressure. During compression, as the capacity of air to hold moisture, i.e. humidity increases, the air becomes wet. This wet air can lead to corrosion in the metallic parts and create disturbances in connected equipment such as pipes, pneumatic tools and also affect the operation of motors and valves. Thus, to maintain the efficiency of air compression systems and other technologies that rely on them, it is essential to keep the compressed air dry at all times.

Compressed air can be dried by altering either heat or pressure of the air. Some commonly used processes are: 

In this process, the air is compressed to a higher pressure than required for compression, leading to free water droplets. These droplets are removed from the air, and the air is then allowed to expand to the required pressure. Over-compression is a highly energy-intensive process and is thus restricted only to small air-flow usage.

It is a simple process in which the air is cooled to cause the condensation of the water vapour present in it. The condensed water droplets are then removed through drain ports and moisture separators. 

Have you ever noticed those little silica gel pouches present in your new water bottles and camera lenses? These are silica gel pouches used to keep objects moisture-free.

Silica gel is a hygroscopic substance. It can absorb water from the surrounding environment. Various hygroscopic substances can be used to remove moisture from compressed air and make it dry enough for further use. 

Modern air-drying equipment combines or enhances the above-explained moisture removal processes to produce dry air for industrial application.

In this method, the air is cooled at the receiving tank. The temperature in the receiving/storage tank is cooler than the compressed air, thus heat transfer occurs from the compressed air to the air in the tank. As this process continues, the compressed air chills down to the tank's temperature and reaches the dew point temperature. At this stage, the water droplets condense out of the air. They are then collected and drained out.

This is an easy and economical method, but it can slow down certain processes due to the time required for the air to cool down.

Aftercoolers are devices that employ heat exchangers to carry out the process of cooling in a systematic manner. The liquid contaminants created as a part of the heat exchange process are typically collected and filtered out, making the air dryer.

There are various kinds of aftercoolers available such as:

Air-cooled aftercoolers – Here, the heat from the compressed air is transferred to the atmospheric air, and the resulting free water droplets are removed through moisture separators. Air-cooled aftercoolers are mobile and easy to install but not nearly efficient enough for high precision usage. 

Water-cooled aftercoolers – Here, water flowing through heat-exchanger tubes are used to transfer heat from the hot compressed air. The temperature gradient here can be controlled better, which can help in greater moisture removal.

Check out Atlas Copco Aftercoolers here.

These work a lot like air conditioners in homes. They are one of the most common types of air-dryers used. They often consist of a refrigerant such as Freon, which removes heat from compressed air.

Water condenses out of the air and is separated, whereas the air is heated up again and transferred for end-usage.

Refrigerant Dryers are highly efficient and can achieve the required humidity levels with ease, making them one of the most demanded air dryers. They are available in both air-cooled and water-cooled variants.

Look into the complete range of Atlas Copco refrigerant dryers, contact an expert.

Desiccants are hygroscopic substances used to maintain a state of dryness. In Desiccant Air Dryers, a unit containing several tiny absorbent beads, made of desiccant materials like silica or activated alumina, functions as the dryer.

The dry air is filtered off the desiccant dust and used for further line operations. Most desiccant dryers use two desiccant-filled towers to run a continuous drying-regeneration cycle and maintain a constant dry air supply.

Desiccant Dryers are commonly used in applications where a high amount of moisture needs to be removed from the air, or the systems are more vulnerable to moisture.

Atlas Copco has a range of high-functioning desiccant dryers. You can choose one according to your requirements here.

Apart from these, processes like Adsorption Drying and Membrane Drying are also sometimes used for drying compressed air. But both these processes are not as widespread for industrial and commercial use.

The ease of installation and maintenance, combined with high efficiency and greater control options, make Desiccation Dryers and Industrial Dryers the most commonly-used air dryers.

If you are looking for an air dryer in the UAE, look no further. Atlas Copco manufactures and sells cutting-edge compressed air solutions, including but not limited to: air dryers, reciprocating compressors, air compressor components and much more. We have earned the trust of thousands of customers over the years and would love to earn yours too.