A nitrogen compressor is a component of a system for purifying nitrogen from ordinary air and storing it in a pressurized state in a cylindrical chamber. Most nitrogen compressor systems as of 2011 work on the pressure swing adsorption (PSA) model, though other commercially-viable methods exist as well. Adsorbent chemicals in the process react with other elements in air such as oxygen to separate them from the nitrogen present, which is then channeled off in a pure form into a nitrogen compressor chamber. In the PSA process, approximately 30% to 35% of the pressurized air that is run through the system is vented back out into the surrounding environment, which is mostly composed of oxygen, and the remaining nitrogen can be up to 99.9995% pure.
A typical PSA system uses a carbon molecular sieve to adsorb the oxygen and trace inert gasses present in normal air. This air is pressurized and channeled through two connected adsorption towers before the purified nitrogen is completely removed and stored in a third nitrogen compressor tank of equal size. The process is rather simple because ordinary atmosphere already contains 78% nitrogen and 21% of the remaining 22% of gasses is oxygen.
The carbon molecular sieve that is used for gas adsorption is shaped like a series of hollow, interlocking fibers that work to permeate out water and oxygen, which can then be vented to the outside environment. Increasing the rate of the separation process as the gas passes over the sieve can reduce the purity of the nitrogen gas end product down to 90%, and this is done depending on the needs of the industry using it in terms of purity and volume. The nitrogen compressor gas end product is generally stored at a pressure range from 102 to 123 pounds per square inch (703 to 848 kilo pascals). Further purification of the nitrogen compressor gas may also be done by passing it over a heated catalyst in the PSA process, which burns off any hydrocarbons, reducing them to a level of less than 0.1 parts per million.
Compressing nitrogen gas has become a common and economical feature of many industries, and is seen as a more cost-efficient solution as opposed to purchasing liquified nitrogen cylinders themselves. The petroleum industry uses compressed nitrogen as an inert gas to prevent explosions in areas where oxygen and other flammable gasses would otherwise be present. Nitrogen gas is also used to temper and braze metals in metallurgy, for industrial cleaning applications, and as a cooling agent in the production of glass.
