What is a PSA Nitrogen Generator and How Does it Work?
PSA Nitrogen generators are pretty common nitrogen generators that we have all around the world. These CGT PSA Nitrogen Generators usually operate on the well-known principle of Pressure Swing Adsorption (PSA) and thus, it is named PSA. Using this principle these generators produce a continuous stream of nitrogen gas from a stream of compressed air.
Here in this cylinder, you will normally have two towers filled with carbon molecular sieve, also known as CMS. The pretreated compressed air usually enters through the bottom of the on-line tower and then it follows up through the CMS. Now, numerous other gases like Oxygen and several other trace gasses are preferentially adsorbed by the CMS, while nitrogen is also allowed to pass through. Now, once a pre-set time is over, the on-line tower will switch to the regenerative mode automatically, also venting the contaminants from the CMS.
Apart from the ordinary activated carbons, these nitrogen generators also have carbon molecular, which are much different from the ordinary activated carbons because they have a narrower range of pore openings when compared to the latter. With these openings, small molecules, small molecules such as oxygen can easily penetrate the pores and can be separated from nitrogen molecules which are too large to enter the CMS. These larger molecules of nitrogen get past the CMS and can easily be collected as the product gas.
What is a Membrane Nitrogen Generator and How Does it Work?
As we all know, the atmospheric air consists essentially of 78% nitrogen and 21% oxygen. This generator filters ordinary dry compressed air and then passes it through a technically advanced bundle of hollow membrane fibers. Here is where the nitrogen gas is separated from the feed air. This is done by the selective permeation method.
Here the water vapor and the oxygen gas are rapidly permeated safely to the atmosphere. On the other hand and at the same time the nitrogen gas is discharged under pressure into the distribution system. Some of the main variables that affect the rate and production of nitrogen are the air pressure, rate of the flow, and the size and quantity of the membrane. The purity of the nitrogen gas or the oxygen content is controlled by stifling the outlet from the membrane bundles.
In case you increase the nitrogen flow at a given pressure and membrane size, you can allow more oxygen to remain in the gas stream. However, this will lower the purity of the nitrogen gas. On the other hand, if you decrease the flow of nitrogen it will increase the purity of the gas. Through this process, you can achieve a purity range between 90% to 99.9% provided you go through the processes well. By combining multiple membrane bundles, an infinite number of flow/purity ranges are available to satisfy practically any application that requires nitrogen gas.
Though the nitrogen generators are used all around the globe and work with complete efficiency for years on end, sometimes you might also face an error or two with them. Here are a couple of errors and how you can fix them:
If your Air Compressor keeps on running
A nitrogen generator works on a nitrogen separation technology. This requires a portion of the air that the compressor produces to be blown off as waste gas. Therefore, the compressor will be running longer to produce a fixed amount of nitrogen when compared to when it produces the same amount of compressed air.
If the Dry/Preaction System of the Nitrogen Generator is not reaching the purity levels promised
It is generally accepted that the nitrogen generators are able to produce nitrogen gas, which is 98% pure. However, it needs to be configured appropriately in order to let this happen.
Here the regulators inside the nitrogen generator should be configured properly to facilitate the maintenance of a certain pressure differential across the nitrogen separation membrane. However, in case these regulators are adjusted in the field by non-qualified personnel, then it could result in affecting both the nitrogen production rate as well as the purity of the gas.