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PSA Nitrogen Generator Introduction

Date: Jun 15, 2023

1 PSA Nitrogen Generator Introduction

1.1 What is PSA Technology

PSA Technology is a very mature technology and has been around since the 1970's. In fact, thousands of PSA plants are serving customers worldwide.

We explain the PSA technology below using a simple process diagram.

PSA process

Air is composed of 78% Nitrogen and 21% Oxygen. PSA Nitrogengeneration technology works on the principle of air separation by adsorbing Oxygen and separating Nitrogen.Pressure Swing Adsorption (PSA Nitrogen) processcomprises of 2 vessels filled with Carbon Molecular Sieves (CMS). (see image below for detail of vessels).

Step 1: Adsorption

Pre-filtered compressed air is passed through one CMS filled vessel. Oxygen is adsorbed by the CMS and Nitrogen comes out as the product gas. After some time of operation, the CMS inside this vessel gets saturated with Oxygen and can no longer adsorb.

Step 2: Desorption

Upon saturation of the CMS in the vessel, the process switches nitrogen generation to the other vessel, while allowing the saturated bed start the process of desorption and regeneration. The waste gas (oxygen, carbon dioxide, etc.) is discharged into atmosphere.

Step 3: Regeneration

In order to regenerate the CMS in the vessel, part of the Nitrogen produced by the other tower is purged into this tower. This allows for quick regeneration of the CMS and to make it available for production in the next cycle.

The cyclical nature of the process between the two vessels ensures continuous production of pure Nitrogen.

PSA process-2

1.2 Technical of PSANitrogenSystem

*Compressed Air System (CAS) 

This CAS offers the compressed air to PSA machine. This CAS should offer very stable pressure andsufficientvolume of compressed air. 

*Air Treatment of Compressed Air System 

First the compressed air goes through the 9th Grade filter then into Refrigerated Dryer.There are 3 reasons why need to equip with Ref. 

Dryer :

a. The Ref. Dryer can force the temperature of compressed air down and condense steam into liquid water with dust and lubricant to drain out. To prevent condensation cause rust in the piping system.

b. To protect the 7th Grade filter after Ref. Dryer, because the 7th Grade filter only can remove liquid water down to 2000 ppm.

c. To enhance the purity of N2.

After Ref. Dryer equip with 2 sets filters:

a. The 7th Grade filter : which can remove the particle down to 1um and oil content down to 1 ppm

b. The 3rd Grade filter : which can remove the particle down to 0.01um and oil content down to 0.001 ppm w/w. The filtration efficiency is99.9995%.

After these Air Treatment, according to the ISO8573-1 standard, the quality of compressed air can reach Class 1. Then the oil-free and dried compressed air can into the PSA machine to produce99.9%N2.

*Pressure Swing Adsorption (PSA) System

PSA is an advanced technology of gas separation.

a. PSA’S Features :

  • Can easy to adjust the purity of N2 by different volume

  • Can operate at low and normal pressure, safe and energy saving

  • Design simple and easy maintenance

  • Automatic control by microprocessor  

b. Carbon Molecule Sieve (CMS) :CMS is the key of PSA Nitrogen Generator. CMS can adsorb oxygen,CO2 and water but not nitrogen. 

c. The principle of PSA :

      At high pressures the CMS has a greater affinity for oxygen, carbon   

      dioxide, and water vapor than it does at low pressures. See below chart;


When air pressure rising, CMS adsorbs oxygen, CO2 and water. When down to normal pressure, CMS adsorbs few oxygen, CO2 and water.

PSA Nitrogen Generator use a pair of absorbers (A and B tower) is filled with CMS and alternately fed with compressed air. While absorber A is producing nitrogen, the CMS in absorber B is being regenerated by depressurization to ambient pressure. After approx. 60 seconds the pressure in the two absorbers is equalized, which means that the compressed air is used to maximum efficiency. It is then the turn of absorber B to produce nitrogen, while the CMS in absorber A is being regenerated.

2.1 About us

Suzhou  Jinhong Gas Co.Ltd established in Oct.1999, located at Panyang industry park, Suzhou City,Jiangsu province China. We are specialist manufacturing varies industry gases ,special gases and forming gas etc, also provide ASU on-site gas supply system&engineering. If your company has any gas or on-site gas production needs, please contact us.

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