Liquid nitrogen is a colorless, odorless, non-flammable, non-corrosive and extremely cold element that finds a lot of applications including research and development.
Liquid Nitrogen Liquefaction :
Liquid Nitrogen Plant (LNP) draws out Nitrogen gas from the atmospheric air and then liquefies it with the help of Cryocooler.
There are two methods through which Nitrogen can be liquefied:
1. Pressure Swing Adsorption with Cryogenerator.
2. Distillation of liquid air.
Working principle of Liquid Nitrogen Plant
In a Liquid Nitrogen plant, the atmospheric air is firstcompressed to 7 bar pressureinto compressor. This high temperature compressed air is then cooled in the external refrigeration system. Then, the cooled compressed air is passed through moisture separator to trap the moisture from the air. This dry compressed air is then passed through a bed of carbon molecular sieves where Nitrogen and Oxygen are separated from the air. Separated Nitrogen is then allowed to get through Cryocooler which cools the gaseous Nitrogen to a liquid state at the boiling point of Nitrogen (77.2 Kelvin). Finally, the Liquid Nitrogen gets collected in Dewar’s vessel where it gets stored for several industrial purposes.
Uses of Liquid Nitrogen
Liquid Nitrogen is used in many applications because of its very low temperature and low reactivity. Some of the common applications are:
· It is used in cryotherapy to remove skin abnormalities
· Serves as a source of an extremely dry gas
· Freezing and transporting of food products
· Cooling of superconductors like vacuum pumps, and other equipment
· Cryopreservation of blood
· Cryopreservation of biological samples like eggs, sperms, and animal genetic samples.
· Preserving of animal’s semen
· Branding of cattle
· Cryosurgery (removing dead cells from the brain)
· Quick freezing of water or pipes to let workers work on them when valves are not available.
· Protects materials from oxidization.
· The shielding of materials from oxygen exposure.
· Otherapplications that include creating Nitrogen fog, making ice-cream, flash-freezing, flowering that shatters when tapped onto a hard surface.
