ACKNOWLEDGEMENT:
Figure
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Source of Figure
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Figure 1
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http://everythingmaths.co.za |
Air as a mixture:
Air is a
mixture of many gases with 78% Nitrogen, 21% Oxygen, and the remaining 1% consists
of Noble gases, water vapours and Carbon dioxide. Argon is the main constitute
of the noble gases present.
Fractional distillation:
Air is a
mixture of many gases with different boiling points. The fractions of air
mainly Nitrogen, Oxygen and Argon are separated using Fractional distillation.
The steps of the process are listed below:
- Air is cleaned to remove dust, using filters of the plant.
- Purified air is dried by passing it through absorbent filters. This is essential as at low temperature, water vapours can solidify to form ice and clog pipes.
- Air is then liquefied using the repetitive processes of expansion and compression.
- At -79°C, carbon dioxide solidifies and is removed.
- The expansion and compression is continued till air reaches a temperature of -200°C, at which it liquefies.
- Figure 1 shows the setup.
- Figure 1:
- This liquid air is fractionally distilled to obtain it fractions according to their boiling points. For example; nitrogen is obtained at -190°C, followed by argon at -186°C and oxygen at -183°C.
- These fractions are collected and separated and stored separately.
Oxygen is
the gas for life. Its fraction obtained from the liquid air has many industrial
uses. For example:
- Oxygen is used in the manufacture of different kinds of steel.
- Oxygen is used in hospitals for patients.
- Oxygen is used in welding and cutting metals. Pure oxygen may increase the welding flame temperature to 3500°C.
