Atmospheric air used to produce Oxygen and Nitrogen, in most industrial processes. Atmospheric air mainly contains the following elements:-
|Element||Percentage Composition by volume||Boiling Point at|
Carbon Dioxide (CO2)
78.5 Deg. C. It solidified
The other constituents of air are Hydrogen and rare gases. Such as, Neon. Helium Krypton and xenon in rates.
The process adopted here to produce oxygen and Nitrogen is called liquefaction and fractional distillation of Air.
Air is mixture of mainly of Oxygen and Nitrogen and its physical properties lie between the two but closer to those of Nitrogen. In its normal atmospheric conditions air is composed principally of Oxygen and Nitrogen and its physical properties lie between the two but closer to those of Nitrogen. In its normal atmospheric condition, air is a colorless odorless gas. Air which is normally in gaseous state can be liquefied, as steam from gaseous state can be condensed to form water in liquid state.
Air is liquefied in our process by expansion in an Expansion Engine and in a Joule Thompson Expansion Valve. As we use an Expansion Engine, the air is to be compressed only to a medium pressure of 45 Kgs. Cm2 whereas other processes need about 150 to 200 Kgs/Cm2 air pressure. Expansion Engine is a single acting reciprocating engine with Inlet and Outlet valves, set to open at a particular time intervals of stroke cycle. Thus, air entering expansion engine through Inlet valve with a high pressure is expanded during the downward stroke of piston. The expanded air will be drawn out through the outlet valves during upward stroke of piston. During such expansion, air gets cooled.
The expanded air from expansion engine and expansion valves will enter the lower part of distillation column.. This air will mostly be liquid.
Distillation is an operation of separating two components having two different boiling points. Thus at a particular temperature in between the two boiling points, one component will be volatile (Thus vapor) and the other component will be liquid. Thus, the component which is more volatile can be drawn out of a distillation column as vapor. The component which is less volatile can be drawn out as liquid. Oxygen and Nitrogen have a difference of about 13 Deg.C. In boiling points and therefore can be separated in a distillation column. Nitrogen will be drawn out as per vapor. Oxygen will be collected as liquid and can be pumped up to 150 Kg/Cm2 by a Liquid Oxygen Pump.