By Ron Marshall
A milk products company was experiencing overheating problems with their air compressor and air dryer. Two small air cooled compressors had been installed in a closed in mezzanine area above the plant. A well-controlled ventilation system kept the space at lower than 70° F, but for some reason the compressors had temperature problems. So bad was the issue that the dryers, installed internally to the compressors, had failed—so secondary external air dryers had to be purchased.
A compressed air auditor was called in to inspect the system. The auditor confirmed that the space in which the compressors were installed was indeed fairly cool, however, there were problems with the ventilation ductwork. The ventilation installers had placed some well-sized ducts above the compressors to remove heat from the room, but there was no connection between the ducts and the compressor. A gap was left between the compressor housing and the ducting, through which very hot cooling air leaked out. The photo at right shows an IR image of the compressor intake showing 104° (40° C) air being sucked into the compressor housing. This is a ventilation short circuit, and not only caused excessive compressor internal temperatures, but also overheated the discharge compressed air.
The air dryers were receiving excessively hot compressed air from the compressors, and in addition to this, the hot ventilation discharge was also overheating the dryer cooling air, causing moisture problems. Both conditions cause the air dryer rating to be exceeded, allowing moisture past the dryer. Ventilation modifications are underway to correct the problem.
Ron Marshall is a compressed air energy efficiency expert at www.compressedairaudit.com
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