Question

What is nitrogen gas used to manufacture on large scale?

Answer 1

Nitrogen (N2) is a colorless, odorless and tasteless gas which makes up 78.09% (by volume) of the air. It is nonflammable and does not support combustion. Nitrogen gas is slightly lighter than air and slightly soluble in water. Nitrogen condenses at its boiling point (-195.8 deg C) to a colorless liquid that is lighter than water.

It is commonly thought of and used as an inert gas; but it is not truly inert. It forms nitric oxide and nitrogen dioxide with oxygen, ammonia with hydrogen, and nitrogen sulfide with sulfur. Nitrogen compounds are also formed naturally through biological activity. Compounds are also formed at high temperature or at moderate temperature with the aid of catalysts.

Nitrogen is the largest consumed industrial gas. Besides steelmaking, It is used in a broad range of industries such as chemicals, pharmaceuticals, petroleum processing, glass and ceramic manufacture, metals refining and fabrication processes, pulp and paper manufacture and healthcare etc. Aside from its chemical name N2, nitrogen is also referred as GAN or GN in its gaseous form and LIN or LN in its liquid form.
Nitrogen is produced in large quantities and at high purity as a gas or liquid by cryogenic distillation and in smaller quantities as a lower purity gas by adsorption technologies such as pressure swing adsorption (PSA) or diffusion separation processes (permeation through specially designed hollow fibers).
Gaseous nitrogen is valued for inertness. It is used to shield potentially reactive materials from contact with oxygen. Liquid nitrogen is valued for coldness as well as inertness. When liquid nitrogen is vaporized and warmed to ambient temperature, it absorbs a large quantity of heat. The combination of inertness and its intensely cold initial state makes liquid nitrogen an ideal coolant for certain applications. Liquid nitrogen is also used to cool materials which are heat sensitive or normally soft to allow machining or fracturing.
Nitrogen is used in the steel industry as purging gas for pipeline purging, as a coolant in the dry quenching of hot coke, as a cooling gas in the blast furnace top, as a carrier gas for conveying of pulverized coal, as an inert gas in the bottom blowing converter, as a shield gas in the heat treatment of iron and steel. It is used in different laboratories for testing and as a process gas, together with other gases for reduction of carbonization and nitriding.

Shrink fitting is an interesting alternative to traditional expansion fitting. Instead of heating the outer metal part, the inner part is cooled by liquid nitrogen so that the metal shrinks and can be inserted. When the metal returns to its normal temperature, it expands to its original size, giving a very tight fit.