Plant Design of Cryogenic distillation of Air to Oxygen and Nitrogen

Air (M.W. = 28.96 g/mol ) is composition of various gases.

  • High purity components in air applied in different chemical industries.
  • 1904- World’s first ASU for production of high purity air components
  • Largest markets - Chemicals and gasification, petroleum refineries, electronics and metals industries.
  • First industrial manufactures of oxygen was ‘Brin process’ 
  • 1806- Faraday liquefied many gases by application of pressure, but not H2, O2, N2
  • 1877- Pictat and Caillete liquefied first O2 and many gases.
  • Prof. Linde- First man producing liquid O2 on commercial scale.
  • 1970s- First application of computer control to improve efficiency and productivity of ASU.

Kolhapur Oxygen Pvt. Ltd. (Kagal MIDC)

Kolhapur Oxygen Pvt. Ltd. (Kagal MIDC)


Global market for industrial and specialty gases will reach 10.15 trillion cubic feet by 2015.

Major growth Factors- high demand from end user industries such as energy, healthcare and electronics.

Growth due to R&D activities focusing on new applications.

Applications of Air Products

  • Medical oxygen
  • Oxygen- Glass manufacturing, chemicals and petroleum processing, pharmaceuticals, pulp and paper (increase paper whiteness), aerospace, wastewater treatment and even fish farming.
  • Oxygen‐enriched air increases production efficiency in steel, rocket fuel, glass, chemical, gasification and metallurgical processing applications.
  • Manufacturers of Al, Cu, gold and lead use oxygen to remove metals from ore.
  • Nitrogen- Oil and gas industries, metal working, electronics, food processing.
  • Refineries, petrochemical plants and marine tankers use gaseous nitrogen to clean out vapours and gases from the equipment they use.
  • Recyclers use liquid nitrogen to cool plastic and rubber so they can grind them and recover key raw materials to manufacture new products.

Process Selection

Different Manufacturing Processes

1. Low temperature (Cryogenic) rectification of liquid air
2. Membrane separation
3. Electrolysis of water
4. Brin process
5. Brin process using cobalt compounds

Cryogenic Air Separation

Two steps

1. Liquefaction
  • Production of low temperatures
  • Linde Process (JT Effect)
2. Separation of liquid air by rectification
  • By integrated distillation column
Equipments used
1. Compressor
2. Heat Exchanger
3. Valve
4. Molecular Sieve
5. Separator
6. After Cooler

Five major steps of manufacturing O2 and N2
1. Air compression
2. Air purification
3. Cooling of air
4. Air separation
5. Product collection

Product Validation
1. Oxygen Test
2. Nitrogen Test

Cryogenic distillation procedure


  • Thoroughly wash all oxygen fittings, valves and parts with clean Tricolor Ethylene /carbon tetra chloride (CTC) before installation.
  • Do not lubricate oxygen valves, regulators, gauges or fitting with oil or any other substance.
  • Do not fasten electric conduits to the plant or its pipelines.
  • Do not experiment with liquid oxygen by putting solids or liquids into it for watching the effect of cold liquid as it may catch fire
  • Pressure gauges across pipes at regular intervals as a check against leaks in the pipes and pressure relief valves for safety vent over pressurized gases
  • No Smoking signs
  • Workers should wear clean, loose fitting, thermal‐insulated gloves; a long‐sleeved shirt and safety shoes.
  • Do not breathe cold oxygen vapor. The temperature of the vapour rising from liquid oxygen is approximately -181 0C.

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