CLAUDE’S Process

Principle

This process is based upon the principle that when a gas expands adiabatically against a piston in an engine, it does some external work, hence its internal energy falls and consequently the temperature of the gas falls. This principle combined with the Joule-Thomson effect, has been applied in the Claude’s process for liquefaction of air.

Procedure

The purified air i.e. air free from CO₂ and water vapours is first compressed to about 200 atmospheres by compressor. The compressed air then passes through the tube which bifurcates the incoming gas part of the air goes into the cylinder fitted with an air tight piston and rest of the air passes through the spiral coil which ends in a jet. The air that goes into the cylinder pushes the piston and thus does some external work. As a result, the internal energy of air falls and hence temperature falls. The cooled air then enters the chamber at lower end. The air that passes through the spiral coil is cooled by Joule-Thomson effect as it comes out through the jet in low pressure region (50 atm) of chamber. The cooled air is circulated again and again with the incoming air till the air gets liquefied. The liquefied air collects in the chamber and is withdrawn.