Infrastructure

For cost reasons, the condenser is operated exclusively with liquid nitrogen (LN2) for precooling. The central condenser supplies ten institutes in Darmstadt.

The liquefaction capacity, stated in litres of LHe dispensed in dewars, was about 32,000 litres per year in the past years. Liquefaction capacities of 80,000 litres per year have even been achieved. The helium stock at the plant is 7,000 litres, which is purified and liquefied in the plant as liquid helium (LHe) at a value of about 17 € per litre (purchase price). The costs for liquefaction amount to 0.42 € per litre. The gas losses of the LHe users vary between 1% and 6% depending on the care of the users and operating conditions.

The helium from the centrally located institutes that evaporates at the users is returned to the recompression plant via pipelines about four kilometres long. The more distant institutes return their helium gas compressed in cylinder bundles.

Plant components

• Liquefier TCF 20 with a liquefaction capacity of 27 or 54 litres per hour
• Condenser DS 170 with a power drain of 100 kW
• Oil separation and oil adsorbent
• Gas adjustment station and gas dryer
• Storage tanks for 2,600 respectively 1,100 litres of liquid helium
• Clean gas storage tank for 5m³
• LN2-tank for 11m³

Recycling components

• 2 gas balloons with a volume of 10 m³ each for collecting the recycled helium
• 3 compressors, each capable of compressing 40 m³ per hour
• HD filter combination
• Seccant high pressure compressor
• 5 high pressure tanks for a total of 17 m³
• 2 bundling stations for a total of 12 gas cylinder bundles
• 2 feeding stations for filling and emptying cylinders
• Clean gas feed into the helium network of the TU Darmstadt