A Study in Nitrogen

Nitrogen (N2) is a colorless, odorless and tasteless gas that constitutes 78.08% by volume of the air we breathe. Nitrogen is an inert gas.

Nitrogen occurs in all living organisms. It is a constituent element of amino acids and thus of proteins and nucleic acids (DNA and RNA). It resides in the chemical structure of almost all neurotransmitters, or in other words, nitrogen is an important chemical in the thinking process. As you read this article you are utilizing nitrogen to connect cognitive thought patterns via synapses in your brain.

The bulk of nitrogen produced in the United States is done via cryogenic separation of air; air is supercooled to a liquid state, and the different gases stratify, just as water and oil do in a glass. Nitrogen is then pulled out as a liquid. Air separation plants can be large facilities serving multiple customers covering several states, or site specific for large users of nitrogen. Cryogenic nitrogen purity can vary depending upon need, but can hold in the ppb (parts per billion) of contaminant gases.

A method of Nitrogen production gaining rapid favor for its ease of installation and relatively low cost are nitrogen generators that separate the nitrogen from air in the gaseous phase, either through the use of a membrane, or via pressure swing adsorption (similar to regenerative air dryers). These units are fairly small in size and production volumes (roughly 100-10,000 scfh per system), but can be 1/10th to 1/100th the cost of a cryogenic separation plant. However, gaseous nitrogen generators don’t produce pure nitrogen – they actually remove oxygen. So while the oxygen content can reach less than 10ppm, there will still be other gases present in the nitrogen that are also present in air – gases like argon, helium, carbon dioxide, etc. In many applications, this is acceptable, as the nitrogen is being used because oxygen cannot be present in the process.

Nitrogen has many commercial and technical applications. As a gas, it is used in heat treating of primary metals; blanketing of oxygen-sensitive liquids and of volatile liquid chemicals; the production of semiconductor electronic components, as a blanketing atmosphere; the blowing of foam-type plastics; deaeration of oxygen-sensitive liquids; the degassing of nonferrous metals; food processing and packing; inhibition of aerobic bacteria growth; magnesium reduction of aluminum scrap; and the propulsion of liquids through pipelines.