In everything from electronics to steel-making, environmentally-friendly soldering to heat treatment and fabrication to food production, not to mention environmental protection, nitrogen has much to offer. The reason: as a gas it is very inert, and with a boiling point of -196oC, as a liquid, nitrogen is very cold. It is also very abundant – nitrogen makes up 78 percent of the air we breathe – and is easily separated from air.
Nitrogen is used extensively in industrial processes that need to take place in an oxygen-free environment, for example heat treatment of metals, and in industries such as chemicals, glass and electronics. Because it is so cold, liquid nitrogen offers an ideal environmentally-friendly alternative to the use of hydrofluorocarbons (HFCs) and hydrocarbofluorocarbons (HCFCs) as a refrigerant in freezing and chilling applications. It also plays an essential role in applications involving high temperature superconductors.
Industry's flexible friend
Nitrogen gas has a wide application in a range of industrial processes where it is often used for displacing unwanted gases and vapours. In the chemicals, electronics and metals industries, nitrogen gas is used to push, or purge, unwanted gases or hydrocarbons out of process equipment. Nitrogen can also be used to displace other dissolved gases from solution in a process known as sparging. In nitrogen inerting, a blanket of nitrogen gas is used to exclude oxygen, water vapour or other chemical vapours from a storage vessel or reactor.
The chilling properties of liquid nitrogen are put to use in a number of industrial applications. For example, in cryogenic grinding, liquid nitrogen is used to chill or freeze materials down to their embrittlement stage (for example, plastics or rubber) so that they can be ground to a powder in high speed mills. Cryo-grinding can be used for recycling of waste plastic for use in products such as epoxy paint.
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