Compressed air dryers are essential elements of your compressed air system. While moisture in your compressor installation is unavoidable, the problems this moisture creates downstream can be large. From contamination of end products to damaging pneumatic machinery and other components, leaving this moisture in your compressor system isn’t an option. That’s where an air dryer comes into the picture. Dryers are one of the pieces of equipment (along with aftercoolers) that help dry the wet air – thus protecting your installation from the ramifications of moisture. But which type of compressed air dryer is right for you?
How Do I Choose a Compressed Air Dryer?
Essentially, the right size dryer should dry air at whatever rate your compressor produces air to meet your process requirements. Like everything when it comes to compressed air, there are calculation tools available to accurately calculate the correct dryer and guesswork or simply replacing what was there is likely not the best option. Ultimately there are six major things to calculate to accurately choose the correct dryer:
Maximum air flow in standard cubic feet per minute (scfm)
Desired pressure dew point
Inlet air pressure
Inlet air temperature
Ambient air temperature (and water temperature if condenser is water-cooled)
Installation environment of the dryer
Desiccant dryers can provide an ultra-low dew point, typically around -40°C /-40°F. Having air at a reliable, predictable dew point can be important for demanding applications in industries such as pharmaceuticals and food processing, as well as applications that demand very high-quality air. Refrigerant dryers typically achieve a dew point of about 3°C / 37°F, but they cost less to buy, operate and maintain than desiccant dryers. For applications that require dry air, but do not call for a critical dew point, a refrigerated air dryer would be a terrific option.
Is it Best to Buy an Air Compressor with a Built-In (Integrated) Dryer?
Generally speaking, yes! Especially when space is limited and dry air is required, a compressor with an integrated dryer makes sense. An integrated dryer is engineered to work with the matching compressor. The whole system is packaged in a cabinet that minimizes the required footprint, reduces operating sound level, and provides savings on installation and maintenance costs.
How Important is Dryer Choice in Overall System Efficiency?
It can be especially important. A compressed air dryer that’s not optimized for efficiency can easily add 10% to your overall energy bill, whereas an efficient compressed air dryer should only contribute around 2% maximum. The drying technology and dryer size you select should complement your compressed air flow rate and air quality requirements. For example, if your compressed air use is comparatively small, the added energy cost to purge a heatless-type dryer can be offset by the lower cost of the equipment. However, for processes with higher demand for compressed air, the investment in heated purge or blower dryers pays for itself through greater energy efficiency.
Over the last five years, dryers have gotten smaller, which improves space utilization. Better controllers are improving system management. Advanced connectivity is enabling remote monitoring and service. Perhaps the most significant change is the continued development of refrigerant dryers with Variable Speed Drive (VSD). In most industrial operations, compressed air demand fluctuates, but a traditional air compressor has just one speed: full capacity. If less air is needed, a lot of energy is consumed and wasted. VSD technology, both in air compressors and dryers, saves energy by automatically adjusting the motor speed to match air demand. In dryer technology, this also ensures a consistent stable dew point while saving energy.
Learn more about the newest refrigerant and desiccant dryer innovations by visiting Dryers OverDew!