Helium liquefiers

A liquefier is an open system which produces a liquid output and requires an equivalent quantity of feed gas as input. The mass flow rates involved in the respective refrigeration process are asymmetric.


Depending on the requirements and specific application, Linde Kryotechnik offers a range of standard and special systems for helium liquefaction. The helium liquefaction capacity of Linde systems ranges from 20 to more than 3500 liters per hour out of a single cold box.

The basic requirements for a user to size and design small to medium helium liquefaction systems are quite multilayer. The feed gas composition, for example, defines whether an internal adsober system can remove impurities or if a purifier (internal or external) is required, and if the purification operation is a continuous or batch process.

Furthermore, the liquefaction rate of the system is dependent on the running time, e.g. if the system is operated during the whole week or stopped on weekends and if a turn-down of the system is required. This will also determine the size of the liquid dewar and storage tank.

The circumstances determine whether the standard L-Series, variations of the standard equipment, or special systems deliver the solution.



Customers for small and mid-size systems appreciate the L-Series as a safe, user-friendly system. Its’ reliability and high-quality equipment are particularly emphasized.

Linde provides standard helium liquefiers based on two different technologies:

  • turbine expander: highly reliable, low operation and maintenance cost
  • piston expander: cost-efficient, easy installation

Performance variations are realized by different cold box sizes, varying compressor sizes, and using liquid nitrogen pre-cooling. All L-Series helium liquefiers include an internal freeze-out purifier to remove dry air contaminants from recovered helium.

The control system can be fitted with online access for supervisors or Linde’s service department.

Turbine Expander: Linde Kryotechnik developed the L-Series equipped with turbine expanders (L70, L140, L280) especially to meet the needs of universities and research institutes with a liquid helium requirement of 20 to 290 Litre per hour.

Piston Expander: The piston expanders (L1410, L1610, and L1620) broadens the product range for small liquefaction capacities.



Special liquefiers

For gas producers and institutes with high helium demand.

Most of the helium that is captured in natural gas fields is liquefied in a Linde Kryotechnik system. For gas producers who market helium worldwide, as well as research institutes with helium requirements above the standard ratings, Linde Kryotechnik has developed a series of special systems with a liquid helium output ranging from 350 to well over 3500 l/h. In bulk liquefier systems, impurities are removed from the helium before liquefaction in separate process steps, such as pressure swing adsorption. In these units, physical, chemical, or cryogenic processes are used for the accumulation/liquefaction of impurities.

The main components of a helium liquefier are:

  • oil-injection screw compressors
  • vacuum-insulated cold box
  • aluminum-plate heat exchanger
  • TED expansion turbines with dynamic gas bearing
  • liquid helium storage tank
  • control system

Further system components such as:

  • raw gas compressors
  • purification systems
  • gas storage tanks
  • helium recovery
  • filling stations

are designed, supplied, and installed by Linde Kryotechnik.