Air Treatment/N2

So you need nitrogen in your plant! In a high percentage of cases, generating your own nitrogen using commercially available equipment is a very cost effective alternative to purchasing liquid nitrogen or cylinder nitrogen from traditional supply sources like the industrial gas companies. In some cases, the return on investment (ROI) ranges from six months to 2 years, but ROI can range, depending on several factors, to several years while still being a good investment. With rising fuel and energy costs, the cost of liquid nitrogen is going up and is making it much easier to justify the purchase of a nitrogen generator in a wide range of purities and pressures.

One of the many tasks in assessing a compressed air system supply side is to analyze the air treatment system for appropriateness and efficiency. Most compressed air systems have one or more air dryers in place to remove the water vapor contained in the compressed air produced by the system air compressors. If there is no air dryer, the normally hot saturated air produced by the air compressors will cool in downstream system components, and condensed water will form in pressurized system pipework.

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 and 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.