How a Nitrogen Generator Works

Nitrogen generators have been revolutionizing the food packaging, laser cutting and brewery industry for years. But their inner workings are still a mystery to most people, especially those who are not intimately involved with the industry. A nitrogen generator is a machine that alters the makeup of the air inside a controlled space so that it consists of nitrogen only instead of its usual structure (a combination of nitrogen and oxygen). This is typically useful in preserving packaged items and in any situation where oxygen and moisture hinder progress or damage finished products.

There are two types of nitrogen generators; membrane generators and Pressure Swing Absorption (PSA) generators. While the membrane generator is a simpler system, its more complex counterpart, the PSA generator, offers greater control over output quality. Both systems incorporate a system that separates oxygen from nitrogen. This action results in the removal of all other air components such as oxygen and moisture, leaving the space occupied by nitrogen.

Membrane Nitrogen Generators

The membrane generator is designed to force compressed air to pass through a specially designed membrane (a hollow fibre membrane). As the air passes through the membrane, the oxygen (and any moisture in the processed air) is released into the atmosphere, and the nitrogen is left behind. The special fibres in the membrane are designed to allow oxygen to pass through but not nitrogen, once pressure is applied. As the oxygen is filtered out, the nitrogen is directed into the generator’s distribution mechanism.

In this type of nitrogen generator, operators can manage the purity levels of the nitrogen by manipulating (throttling) the outlet. By doing things such as reducing the pressure or the rate at which air flows through the system, operators can determine the volume of oxygen that is allowed to enter the processed air. This comes in handy when nitrogen purity levels below 100% are required.

PSA Nitrogen Generators

PSA (Pressure Swing Absorption) nitrogen generators typically comprise three large vessels connected by a piping system strategically designed to facilitate the processing of ordinary air into nitrogen.  Air that is processed by a PSA nitrogen generator first enters a vessel that contains a molecular sieve. As the air is pressurized, the sieve absorbs the oxygen particles while the nitrogen particles are directed towards another container. In this container, the nitrogen particles are stored until needed. A second vessel picks up the slack by starting the separation work in another batch of compressed air. This process continues for as long as a continuous supply of nitrogen is needed. In other words, once one vessel is empty, it will pick up where the previously filled vessel stopped. Once the nitrogen has been removed, the vessel’s pressure is released into the surrounding air, and along with it, the oxygen.

A nitrogen generator is a useful solution for any operation that requires a constant supply of high-quality pure nitrogen.  Despite that fact that these generators started off being used in a limited number of industries, today they form an essential part of operations in the food production, automobile (including aircraft), gas and oil industries.