Separation Of Components from Air

  This process is based on difference in boiling point of the components in the mixture. This is a special type of distillation. The liquid air  made earlier is  is allowed to warm-up slowly in a fractional distillation column. There, the gases get separated at different heights depending upon their boiling points.

The Joule-Thomson effect is used in this procedure.  Pure, dry air is fed into a compressor, which compresses it to around 200 atmospheres.  The heat of compression is then removed by passing it through a conduit cooled by a refrigerating liquid such as liquid ammonia.

  Air generally contains impurities such as carbon dioxide, sulphur dioxide and hydrogen sulphide etc. And the air contains dust particles also. To remove these particles purification of air method is done. It consists of following steps: In the first step the air is washed by passing through water where the dust particles are removed. Then the washed air is passed through dilute caustic soda solution where the gases like carbon dioxide, hydrogen sulphide, sulphur dioxide etc. are removed,  as the gases present are acidic and caustic soda is a base. The purified air now contains moisture. Then the moist air is passed through pipes which is maintained below -20°C where vapor present in it freezes and the air becomes dry. And now the air is free from all impurities.