Helium liquefaction

General process description

The liquefier is a fully automated, processor-controlled refrigeration system with a screw compressor, expansion turbines and an integrated purifier for processing contaminated helium (He).

Features & Benefits

• Universal application (liquefier, refrigerator, radiation shield cooling)
• Simple operation
• Fully automated operation
• Automated purifier without external cooling
• Modular, compact design
• Extremely quiet and vibration-free
• No special fastenings or foundations required
• Optional – performance increase through LN2 pre-cooling

The cooling process

The cooling takes place after the Claude process.

Compression

A screw compressor compresses purified helium from 1.05 to approx. 12.5 bar, constantly dissipating the resulting compression heat. Traces of oil in the circulating gas are removed by coalescer filters and a special oil absorber.

Expansion

The actual refrigeration is generated by two dynamic gas-bearing expansion turbines connected in series, whereby part of the circulating gas is expanded while performing its work. In stationary operation, the final temperature after the second turbine is approx. 12 K.
At temperatures below 8 K, part of the circulating gas is expanded to approx. 1.3 bar by a Joule-Thomson valve (JT). This produces partly liquid helium with a temperature of approx. 4.5 K. In the transfer line, the 4.5 K cold helium is transported from the Joule-Thomson valve to the liquid helium dewar.