Industrial gases Oxygen, Nitrogen and Argon produced from air separation process. Earth atmospheric air contains these three components in terms of volume percentages as 20.94%, 78.09% and remaining argon respectively and other gases like carbon dioxide in fraction. By liquefying and distillation technology air is converted to liquid and separated based on the boiling points of the nitrogen and oxygen.
Different types of air Separation process technology for industrial gases production:
By the thermodynamic principle, pressure work and temperature parameter contribute to develop and control a system to obtain air separation at low temperatures.
- Cryogenic distillation
- Separation based on differences in molecular weights
- Separation based on molecular size
- Non-cryogenic separation processes
Cryogenic distillation processes:
All standard cryogenic processes include these steps,
- Filtering and air compression
- Removal of water and CO2
- Cooling the air
- Distilling the partially-condensed air
- Warming gaseous products
Cryogenic processes cost effective for high production rates. Pure products are obtained. Insulation of the heat exchange system and distillation column play key role in energy management due very low temperatures operations. About 15 to 60 meters a cold box is built to insulate and place all the low temperature operation equipments inside it.
Important sections are:
- Air Separation Unit, ASU
- Oxygen Plant or Oxygen Generator, 7 barg (100 psig)
- Nitrogen Plant or Nitrogen Generator, 6-8 atm
- Refrigeration system for liquid form products
Membranes or adsorbents are used to remove the unwanted components of air by PSA/ VPSA technology. Pressure swing adsorption (PSA) separates air to oxygen with 90 to 95% pure and nitrogen with 95 to 99.5% free of oxygen. However, the process is less energy efficient and so preferred for less production rates and small plant capacity for flexible start and stop operation.