Air separation

Air separation is a way to take the air we breathe and split it into its main parts, like nitrogen, oxygen, and sometimes argon and other rare inert gases. We need to do this because different jobs and factories need these gases to be very clean and pure so that things work right.

The usual way to split air is by a process called fractional distillation. Big factories, called cryogenic air separation units (ASUs), use this method to make nitrogen, oxygen, and often argon. There are also other ways, like using special membranes or processes, to get just one kind of gas from the air.

Very clean oxygen, nitrogen, and argon are needed to make tiny parts for things like computer chips, and this can only be done using cryogenic distillation. Rare gases such as neon, krypton, and xenon can also be found by distilling air in special setups with many distillation columns. Advanced air separation can even help us find helium, which is used in many important jobs.

Cryogenic distillation process

We can get pure gases from air by cooling it until it becomes a liquid. The different parts are then separated based on the temperatures at which they turn from liquid to gas. This method makes very pure gases but uses a lot of energy. It was first made by Carl von Linde in 1895 and is still used today.

The process needs special equipment to work well and stay cool. It uses a cycle that makes things very cold, and the cold parts are kept inside an insulated box. A machine called a compressor helps provide the energy needed. Modern machines sometimes use turbines to help save energy. The steps include cleaning the air, compressing it, removing water and other substances, and then cooling it in a special exchanger to separate the gases.

Applications

Air separation is used in many important ways. For example, liquid oxygen and nitrogen help companies like SpaceX build rockets.

Hospitals use pure oxygen to help patients. In steelmaking, oxygen is needed to make steel. Nitrogen is also used to make ammonia.