12 February, 2020
Estimated reading time: 5 minutes
The air we breathe contains about 78% nitrogen. That said, nitrogen at a higher level of purity has a wide variety of practical applications across many industries. To achieve this, nitrogen molecules are separated within a clean, dry compressed air stream. The result is a purified supply of nitrogen gas. With a PSA nitrogen generator, you can do this in-house.
For some applications, such as tire inflation and fire prevention, relatively low purity levels (between 90% and 97%) are required. Other applications, such as food/beverage processing and plastic molding, require higher levels of purity (from 97% to 99.999%).
While higher purity levels are used in industries like food processing, for lower purity needs, often generating nitrogen using membrane technology is preferred. This method uses selective permeation to separate nitrogen from other gases.
Diversifying your knowledge on these methods ensures you're well-equipped to choose the best nitrogen generation solution for your specific needs. Learn more about membrane nitrogen technology to see its benefits and uses.
Watch this video to learn more about Nitrogen
Pressure Swing Adsorption (PSA)
One method for generating nitrogen is Pressure Swing Adsorption (PSA). Adsorption is the process where atoms, ions, or molecules from a substance, like compressed air, adhere to the surface of an adsorbent.
A PSA nitrogen generator isolates nitrogen. The other gasses in the compressed air stream (oxygen, CO2, and water vapor) are adsorbed, leaving behind purified nitrogen. This equipment is a simple, reliable, cost-effective approach to nitrogen generation. It enables continuous, high-capacity nitrogen flow at desired purity levels.
Two tower system
PSA traps oxygen from the compressed air stream when molecules bind themselves to a carbon molecular sieve. This happens in two separate pressure vessels (tower A and tower B). Each of these is filled with a carbon molecular sieve that switches between a separation and regeneration process.
Clean, dry compressed air enters tower A. Since oxygen molecules are smaller than nitrogen molecules, they pass through the pores of the sieve. Nitrogen molecules cannot fit through the pores so they bypass the sieve. This results in nitrogen of desired purity. It is called the adsorption or separation phase.
Most of the nitrogen produced in tower A exits the system ready for direct use or storage. Next, a small portion of generated nitrogen flows into tower B in the opposite direction. This flow pushes out the oxygen that was captured in the previous adsorption phase by tower B.
By releasing the pressure in tower B, the carbon molecular sieves lose their ability to hold the oxygen molecules. These detach from the sieves and get carried away by the small nitrogen flow coming from tower A.
This "cleaning" process makes room for new oxygen molecules to attach to the sieves in the next adsorption phase. The two-tower PSA system switches between separation and regeneration to provide continuous nitrogen production at a desired purity level.
Generate nitrogen in-house
Ask an air system professional about the best solution for generating nitrogen in-house.
Nitrogen plays a big role in various industrial applications. This e-book on nitrogen generation will help you understand the growing trend of on-site nitrogen generation and how this will benefit your business.
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