Moisture in compressed air is troubling for manufacturing and production facilities. Manufacturing quality becomes an issue when excess moisture is present in production facilities. Inferior products create reliability concerns and entire production batches may become invalidated.
Humid compressed air affects pneumatic equipment, too. Machinery suffers from corrosion, reliability problems, and equipment failure.
Air compressor dryers remove moisture from compressed air before it is used inside the plant. Several types of compressed air dryers exist:
- Refrigerated air dryers are the most common and affordable drying system. They can drop air temperatures to as low as 3° Celsius (approximately 37° Fahrenheit).
- Desiccant dryers absorb moisture, sometimes include internal heaters, and can achieve sub-zero air temperatures. These are ideal for low moisture tolerance manufacturing and related operations.
- Membrane dryers capture moisture usually without requiring energy to operate. Overall, they are less capable yet offer substantial potential energy savings.
So… let us start with the basics.
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What is an Air Compressor Dryer?
They are integrated into a planned air compressor system or as an addition to an existing air system when the internal aftercooler is insufficient.
During the compressed air production process, excess water is unavoidably generated. Compressor dryers separate water vapour from compressed air. Dryers and an aftercooler extract moisture before dry compressed air distribution. However, for demanding systems, an aftercooler is insufficient, especially to achieve the lowest moisture levels.
Air dryers are essential to reduce moisture content. When reaching the dew point, vapour transforms into liquid form. This leads to air compressors experiencing accelerated internal corrosion or lines freezing at bone-chilling temperatures.
Robustly drying compressed air extends the life of a compressed air system. Air-fed equipment and expensive manufacturing facilities are better protected.
Types of Air Compressor Dryers
Below, we explain the main types of air compressor dryers:
Refrigerated Dryers
Refrigerated dryers use condensation to remove moisture. Heat exchangers process heated compressed air, cooling it down. After cooling, water separates and is released through a special drain.
These dryers are efficient, achieve reasonable reductions in temperatures (near zero degrees), and run economically. When sub-zero compressed air temperatures are not required, they are often sufficient for industrial operations.
Desiccant Dryers
Desiccant dryer systems use heated desiccant material to collect moisture from the air that passes through. The material is similar to the tiny packets of absorbent silica found inside new luggage and apparel. Some of these desiccant dryer systems also include internal heaters or blower purge features to further enhance their capabilities.
These dryers may achieve temperatures of minus 20°C (minus 4°F) to minus 70°C (approximately minus 94°F). Desiccant dryers are the best option for industries requiring cooled compressed air with minimal moisture.
Membrane Dryers
A membrane dryer relies on membranes to dry air efficiently. Water vapour is captured before it condenses into H2O. This prevents contamination and moisture damage to equipment.
While membrane dryers do not require electricity to operate and are fairly quiet, they have capacity flow limitations and may not be suitable in all situations.
It is important to understand which air compressor dryer system is right for you. Get free air system advice by talking with our specialists at J LL Leach.
How Air Compressor Dryers Work
Air compressor dryers process air. They remove moisture and lower the dew point, enabling dry compressed air distribution to downstream equipment and elsewhere. Operators seek the most appropriate air compressor dryer based on specific needs.
Dryer systems use different cooling and moisture extraction mechanisms:
Refrigerated Dryers: heat exchangers cool the compressed air, condensing water and expelling it. They manage above-freezing air temperature levels and remove moisture well. Medium air flow capacity is achievable. Energy efficiency is reasonable, too.
Desiccant Dryers: moisture-absorbing desiccant material captures water vapour content. This material is recycled. High air cooling capacity is possible at sub-zero temperatures. Moisture is successfully captured almost in its entirety, making desiccant dryers applicable for manufacturing facilities that require extremely dry air.
Membrane Dryers: permeable replaceable membranes strip water vapour while allowing cooled air through. As a lower-capacity dryer, maintenance is reduced, installation is more straightforward, and no electricity is required. Membrane dryers are primarily applicable for low flow, direct applications for isolated purposes, not as part of large commercial air systems.
Choosing the Right Air Compressor Dryer
To select the right air compressor dryer, it is necessary to have a clear understanding of current and future compressed air needs. Factors such as the operational environment, air quality requirements, energy usage, ongoing costs, maintenance, and other aspects are highly relevant.
For example, a medium airflow requirement from a small manufacturer outside of the pharmaceutical and food & beverage industries may only need a refrigerated dryer. A cycling dryer of this type turns on and off as needed, saving electricity and reducing wear.
In another situation, minimal moisture in compressed air may necessitate using a heated desiccant air dryer. This dryer type delivers extremely low moisture levels, excellent reliability, and high air volumes to support operations.
Under certain circumstances, a membrane air dryer is the most energy-efficient option, supporting a low airflow and moderate moisture requirement.
Maintenance and Troubleshooting
No dryer is maintenance-free. Regularly scheduled maintenance includes checking for leaks and attending to filters and drains. A critical comparison of the dryer’s performance to its production specifications is useful, too.
Resolving moisture issues and fixing root causes, refitting or replacing parts, identifying noise causation and finding solutions, patching air leaks, checking drains, and replacing filters are the main requirements.
Industry Applications and Case Study
Moist air enters industrial air equipment and requires either cycling or non-cycling dryers to reduce moisture levels. A wide range of industrial applications is possible for air systems, but moisture level requirements are a critical factor.
Heated desiccant dryers and heatless desiccant dryers reduce water vapour in the air. Industrial operators, such as food producers and pharmaceuticals, require extremely dry air, and these dryers are ideal for them. Dryers are critical equipment within high-quality air systems. With pressurised air, proper dryer selection is essential.
Case Study: Single Variety, a boutique UK jam manufacturer, required an upgraded compressed air system. A refrigerant dryer was introduced. It supported increased jam-filling capacity alongside existing jam depositors, jar capping, and labelling services supported by compressed air.
Conclusion
Air dryers are an important part of complete air systems. While an aftercooler reduces compressed air temperatures and cuts moisture levels, they are insufficient for common industrial applications. Air dryers fully support air systems by removing moisture in compressed air and lowering air temperatures.
Selecting the most appropriate air dryer requires an air systems professional. J LL Leach employs a team of knowledgeable staff to review your requirements and confirm the dryer type needed. Get in touch with us today.
