Desiccant air dryers are products that are specifically designed to extract water vapour from industrial compressed air systems by absorbing moisture using a desiccant material which is then, for example, regenerated by blowing air through the dryer. Desiccant air dryers are commonly fitted to compressed air systems to prevent moisture from condensing within pipe work and equipment. They are typically utilised where compressed air is needed at higher quality or with a lower dew point than can be achieved by a refrigerated air dryer. Desiccant air dryers available through the ETL must incorporate a dew point sensing control and must either use a regeneration method which is heatless or electrically heated (either internally or externally).
Controlling multiple compressors around a single set pressure prevents pressure fluctuation common in simple cascade or sequence controls. Optimising which compressors are selected ensures that utilisation is maximised while closely matching demand. Predicted stop/start based on pressure decay optimises system performance by predicting when best to start/stop or load/unload the next compressor in sequence by monitoring the decay/rise in system pressure. Variable pressure according to production demand can also be used to vary pressure according to specific production requirements, e.g. lower weekend pressure.
Refrigerated dryers are used to remove the moisture present in compressed air before it is used. Drying the compressed air prevents liquid water forming downstream where it can contaminate or damage the system causing operating problems, costly maintenance, and repairs. Drying is achieved by cooling the air so forcing any moisture present to condense. The moisture is then collected and drained from the system. A refrigerated air dryer typically increases the energy used in the compressed air system by between 2% and 5% depending on product type and how it is controlled. Refrigerated air dryers with energy saving controls can moderate their energy use in line with compressed air demand. As the compressed air demand falls so does the demand on the dryer. Dryers with such controls typically use 30% less energy than non-modulating products.More information (PDF)