Nitrogen has multiple commercial uses and is also used in labs. Analytical chemistry, petroleum industry, metallurgy and pharmaceutical industry are some of the areas where nitrogen is used. A nitrogen generator is used to produce nitrogen gas for the above-mentioned purposes. Nitrogen generators are mobile or stationary air-to-nitrogen producing complexes. These machines or devices produce nitrogen from the air for industrial, commercial or scientific uses. There are 2 ways a nitrogen generator works, one is using a PSA technology and the other is membrane technology.
The Pressure Swing Adsorption technology separates gases by fixing gas mixture particles and components by a solid physical substance. These are known as adsorbents. In the PSA process, there are two towers with carbon molecular sieve or CMS. Pretreated compressed and purified air passes through these towers. The air enters from the bottom and moves up. Oxygen, as well as other trace gases, are adsorbed by the carbon molecular sieve, while nitrogen passes through. The adsorbed oxygen is then released into the atmosphere. After a pre-determined time, the on-line tower moves to regenerative mode to vent the contaminants from the CMS. CMS has narrow pore openings that allow oxygen to enter but not nitrogen as the molecules are larger for nitrogen. The two towers alternate between adsorbing oxygen and then releasing it into the atmosphere. In this case, the cost of operation is low for producing gas that is 99% pure. The environmental impact is also less if PSA is used.
Gas Membrane technology
The gas membrane technology is based on the ability of different gases to permeate a substance of fiber. Some gases permeate faster while others permeate slower. The air around us has 78% nitrogen, 21% oxygen and 1% of other gases. A membrane system that allows permeation uses this air to produce different purities of nitrogen. The main principle in this process is selective permeation as each gas has a different ability to fuse or dissolve through a membrane. Differential partial pressure is used in the separation process, created between low-pressure membrane side and compressed feed airside. The membrane separator is a cylinder with hollow fibers. The outer surface of fibers is non-porous but permeable. Compressed air is fed into the separator, which flows through the fibers. On the way, air molecules start to permeate the fiber. Faster gases like oxygen permeate the fiber quicker than nitrogen. Nitrogen gas then comes out at the other end of the fiber. The purity of the nitrogen gas depends on the flow of air and membrane size.
By bundling multiple fibers and arranging them like a shell and tube heat exchanger, one can process thousands of cubic feet of air per hour. The advantage of this technology is that it is relatively easy to design and create. There are no mobile parts, that increase dependability. However, these generators have limited capacity and can produce gas that has a purity of 95%. Nitrogen gas generator simplifies nitrogen supply and use. Investing in this technology also brings economic benefits, as well as a safe and stable supply.