Why Do People Think Air Separation Plant is a Good Idea

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The air we breathe is made of mixture of different gases such as oxygen, nitrogen and traces of rare gases like argon.  Amongst the mixture of gases, oxygen and nitrogen are the most important both for biological imperatives and industrial applications. In terms of atmospheric composition, oxygen is said to make 21% and nitrogen 78% of Earth’s atmosphere.

Oxygen is a biological necessity as all living beings needs oxygen for respiration for staying alive. Obviously, it is not possible to live without oxygen. Similarly, nitrogen is also biological necessity as it is needed for building up proteins needed for DNA and RNA. Moreover, it is also required for plants and crops though its use must be tempered.  Too much of it will destroy the crops and too little will stun their growth.

Apart from biological use, both the gases are also needed in industrial applications. O2 is valued for its high reactivity and aids combustion. It helps in sustaining numerous industrial processes. On the other hand, nitrogen is inert which finds applications in creating modified atmosphere and numerous other applications. However, industrial applications require both gases to be of high purity. Generally, oxygen must have purity between 95% and 99.7%. Nitrogen must have purity up to 99.99%.

Why Air Separation Plant is a Good Idea

There are many processes or techniques for generating high purity oxygen and nitrogen through various industrial processes. However, the general consensus is that air separation is the best technique for achieving high purity industrial gases.

Air separation is achieved through two processes called pressure swing adsorption (PSA) and cryogenic distillation. Anyone familiar with the industrial gas plant market will agree that both these techniques are widely used in the industry.

Let’s take each one of them and discuss how they work. Let’s start with PSA air separation plant which is based on the adsorption technology. The PSA air separation plant works with air passing through twin towers which contain molecular sieves inlaid with adsorbing material, Zeolite. On passing through the adsorbing material the nitrogen molecules get stuck while oxygen is allowed to pass through and is collected as a product gas.

Cryogenic air separation plant is based on the liquefaction of the air according to the respective boiling points of oxygen and nitrogen. After the intake of air into an air separation unit   it is filtered and compressed. Then, the air is purified in the cleanup system from impurities such as carbon dioxide, hydrocarbon and moisture.

Next the air passes through a series of heat exchangers to achieve liquefaction. Now the air is separated into oxygen and nitrogen in the high pressure distillation column. It is now moved into the low pressure distillation column where it is distilled to meet the desired purity.

These are the two most efficient techniques for generating high purity oxygen and nitrogen. Wide ranges of industries prefer using one of the two techniques. PSA is considered more suitable for small scale businesses with requirement of purity up to 95% for oxygen and 99% for nitrogen while cryogenic is widely used in large scale industries requiring purity up to 99.7% for oxygen and 99.99% for nitrogen.