PSA – What Is It & How Does It Work?

There are many uses for Oxygen and Nitrogen gas in our world today, in fact they are vitally necessary. They are used in such a wide variety of applications, ranging from the food industry to industrial manufacturing. If you have ever enjoyed a packet of crisps, you have utilized a product that uses Nitrogen gas to keep the crisps fresh before consuming. It is a small and silly example of one of many applications, yet it shows how we rely on the gas in our every-day lives, even if we didn’t notice it.

The air we breathe contains 78% Nitrogen, 21% Oxygen, 0.9% Argon and roughly 0.1% other trace gases. This generic combination of gases is so plentiful that it makes absolute economic sense to utilize it as the source of feed gas for Oxygen or Nitrogen gas generation systems. Why would we try and source the gases elsewhere when it is free and plentiful?

In gas enrichment plants, this atmospheric gas is compressed using an air compressor to supply feed air to the generation system. Most Oxygen and Nitrogen generation plants function using a process known as the Pressure Swing Adsorption method (PSA).

The PSA method is where compressed air is forced to pass through a molecular sieve that will allow some gas molecules to pass through while retaining others. The reason that the PSA method is so effective, is that under higher pressures, gases are more likely to be attracted to certain substances; making it easier to separate them using molecular sieves. This separation does not occur at elevated temperatures, making it a cost-effective means of separating the gases.

Essentially, when two or more gases are separated, one gas is enriched while the other is purged from the system. The gas that is being targeted for separation is the gas being enriched. The enriched gas is then stored in a pressure vessel while the waste gas is released back to the atmosphere. Depending on which gas is being enriched, the process for Oxygen and Nitrogen enrichment is identical, only the type of molecular sieve changes. Either a Zeolite molecular sieve will be used for the enrichment of Oxygen, or an activated Carbon sieve for the enrichment of Nitrogen.

The PSA system requires the use of two cylinders that work in sync to ensure a constant supply of enriched gas is supplied to meet the consumers’ demands. This two-cylinder process is known as the Double Cylinder PSA Method. The gas being enriched passes through the first cylinder and reaches a certain purity and pressure, at which point the gas is released into two paths. One path is into the pressure storage container and the second is into the second, but identical, cylinder to repeat the process of the first cylinder.

When a certain pressure is reached in the second cylinder, the gas is released into two paths again. One goes into the gas storage pressure vessel and the other into the first cylinder. This process ensures that gas is constantly being enriched and provides the end user with a reliable and constant source of gas.

There are many uses for these two gases and we at PrepAir specialize in providing these generation units for industrial use. We are able to take your specific requirements and provide a solution that is cost-effective and tailor-made. For any further information please view our Product Page or contact myself for any further information.