Air separation

Air separation is a process that takes the air we breathe and separates it into its main parts, such as nitrogen, oxygen, and sometimes argon and other rare inert gases. This is important because different industries need these gases in very pure forms to make things work properly.

The most common way to separate air is through a method called fractional distillation. Big factories called cryogenic air separation units (ASUs) use this method to produce nitrogen, oxygen, and often argon. There are also other methods like using membranes or special adsorption processes to get just one type of gas from the air.

Very pure oxygen, nitrogen, and argon are needed for making tiny electronics 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 multiple distillation columns. Advanced air separation can even help us find helium, which is used in many important applications.

Cryogenic distillation process

Pure gases can be taken from air by cooling it until it turns into a liquid. Then, the different parts are separated based on the temperatures at which they change from liquid to gas. This method creates very pure gases but uses a lot of energy. It was first created 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 for a process that makes steel, using nearly two tons of oxygen for every ton of steel. Nitrogen is also used to make ammonia, and large amounts of oxygen help turn coal into gas in some projects.