Gas Liquifier

In simple terms liquifier is defined as a unit to condense gas and convert them to liquid form. Liquefier is a refrigeration unit in an air separation plant where high percentage of liquid gases are produced. The primary fluid used in a liquefier is nitrogen.

The Liquifier capacity is determined by an analysis that considers local plant backup needs and anticipated demand for merchant liquid products to be supplied out of the plant. As a consequence, the ability to produce liquefied product may range from a small fraction of the air separation plant capacity up to the plant's maximum production capacity for oxygen plus nitrogen and argon.

Most gas liquefiers use expansion engines to pre-cool the gas close to its liquefaction. Helium and Hydrogen liquefiers usually contain two or more expansion engines at successive temperatures, with multiple heat exchangers.

Hydrogen Liquefier
Hydrogen in the form of a pure gas at approx. 20 bar is fed into the vacuum-insulated cold box and, after a certain degree of supercooling at the end of the refrigeration process, it expands through a Joule-Thomson valve into the tank where liquefaction subsequently takes place.

Helium Liquefier
In bulk liquefiers, contaminants are removed from the helium prior to liquefaction in separate components where cryogenic, physical or chemical processes are used for accumulation/liquefaction of contaminants and for adsorption under pressure variation.

Components of Liquifier

• Piston compressors
  
  
• Oil-bearing expansion turbines
  
  
• Liquifier cold box
  
  
• Liquid nitrogen precooling
  
  
• Hydrogen purification
  
  
• Raw gas compressors
  
  
• Storage tanks and filling devices

Liquifier Process

• Liquefier takes in near ambient temperature and pressure nitrogen.
  
  
• It then compresses the pressure nitrogen and cools it.
  
  
• Then expands the high pressure stream to produce refrigeration.

In case of oxygen gas production, an extra heat exchanger is provided to re vaporize some of the liquid nitrogen while liquefying the oxygen product.

Advantages of Liquefier

• Improved range of services without expensive additional pipelines.
  
  
• Increased load factors in existing pipelines.
  
  
• Distributed capacitance and/or peakshaving integration with refueling networks.

Applications of Liquefier

• Separation of a mixture of gases
  
  
• Rocket
  
  
• NMR medical imaging