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 14 to more than 3500 litres per hour out of a single cold box.
Standard systems
For universities and research institutes with a liquid helium requirement of 14 to 280 l/h, Linde Kryotechnik has developed the L-series standard liquefiers (L70, L140 and L280). The wide range of performance ratings is achieved by using different compressors and operation with or without liquid nitrogen precooling. Integrated into the cold box is a freeze-out purifier to remove contaminants from the helium. All standard systems are fitted with a Siemens S-7-300 automatic control and monitoring system. A PC system is offered for visualization and remote operation. The control system can be fitted with online access for supervisors or Linde’s service department.
Special systems
For gas producers who market helium worldwide, as well as research institutes with helium requirements in excess of 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 prior to liquefaction in separate process steps, such as pressure swing adsorption. In these units, physical, chemical or cryogenic processes are used for accumulation/liquefaction of impurities.
The main components of a helium liquefier are:
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oil-injected screw compressors
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vacuum-insulated cold box
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aluminium-plate heat exchanger
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TED expansion turbines with dynamic gas bearing
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liquid helium storage tank / dewar
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control system
Further system components such as:
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raw gas compressors
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purification systems
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gas storage tanks
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helium recovery
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filling stations
are designed, supplied and installed by Linde Kryotechnik.