Industrial Utility Efficiency    

Air Treatment

Compressed air is dried to prevent condensation and corrosion which can disrupt manufacturing processes and contaminate products. Water is the primary promotor of chemical reactions and physical erosion in compressed air systems. A myriad of desiccant dryer designs have been devised to provide “commercially dry” air, air having a dew point of -40°F or less, to prevent corrosion.  Desiccant dryers use solid adsorbents in granule form to reduce the moisture content of compressed air.
Nitrogen, an inert gas comprising 79% of the atmosphere, can be distilled from ordinary air. However, companies that use this product in their everyday operations know that it’s not quite that simple and much more expensive than the stuff we breathe. The primary means of obtaining nitrogen for industrial use is to transport it onsite in liquid form, which must be shipped stored at cryogenic temperatures. But, really, what’s the point of turning nitrogen into liquid for shipping, transporting it to where it’s used, and then turning it back into gas?
Production and quality engineers in industries like the food & beverage, pharmaceutical, semiconductor, and chemical sectors have established internal specifications for oil-free compressed air. The product spoilage and safety issues at risk make oil-free compressed air an absolute necessity in certain processes.
Nitrogen gas provides a number of diverse uses for a wide variety of manufacturers. As a sister function of compressed air, on-site nitrogen generation can provide additional opportunities for cost savings and other efficiencies for manufacturers who shift from delivered liquid nitrogen service.
Dewpoint is defined as the temperature to which a gas (e.g. air) must be cooled, at constant pressure, for water vapor to begin to condense to liquid water. In other words, when the dewpoint temperature has been reached, the gas is fully saturated with water vapor.
Hazardous breathing conditions exist in routine industrial operations, such as hospitals, abrasive blasting, paint spraying, industrial cleaning, and arc welding. In these and other operations that introduce contaminants into the workplace, supplied-air respirators are frequently used for worker protection.
The most abundant contaminant in any compressed air system is water. This can be in either liquid or vapour form. Atmospheric air is already very wet, and becomes saturated when compressed. This water vapour will condense when the temperature drops, after the compressor, and will damage air receivers, pipework and equipment. For this reason coalescing filters and then dryers are used to remove the bulk of this water.  
Desiccant dryers are commonly used to bring the pressure dewpoint well below freezing (commonly -40°F) in order to prevent moisture from precipitating in the compressed air system and production equipment.
Compressed air dryers are important items to consider when evaluating the efficiency of a typical compressed air system. One of the keys to optimal system operation is ensuring the air is only dried to the level required by the actual needs of the facility.
This article reviews two major processes in paper mills: compressed air quality and air compressor cooling.  The central air compressor room was expanded and relocated at the largest privately owned paper mill in Canada.  The compressor space was required by a plant expansion, which would occupy the original compressor space for increased production.
Compressed Air Best Practices spoke with the Parker PDF (Purification, Dehydration, and Filtration) Division.