Stirling Cryogenerators have been widely used in the 1960’s and ‘70’s for the production of LH2 at various institutes and research laboratories all over the world. In material science small scale production was used to study the properties and behavior of LH2 and its effect on materials.
In scientific devices, the Stirling Cryogenerators have been used as LH2 re-liquefiers to create cold neutron sources and to run H2/D2 distillation columns. Today, some of these vintage machines are still in use, for instance the one at the National Institute of Cryogenic and Isotope Separation in Romania which was installed in 1973.
After the 1980’s, numerous systems have been supplied by Stirling Cryogenics using a cold helium loop for applications such as space chambers and LH2 cold neutron sources.
A recent project is the re-liquefaction system for the LH2 inventory of the cold neutron source at the Reactor Institute Delft of the Delft Technical university. For the RID, Stirling Cryogenics designed and built a system providing 900 W of cooling power at 20K, in a redundant set-up and with a variable heat load from 10 to 120%.
In the hydrogen market, Stirling offers two propositions:
Liquid Hydrogen production
For production of liquid hydrogen, the two-stage Stirling Cryogenerator is required to reach a temperature of 20K.
Stirling can supply LH2 production systems with a capacity from 5 kg/day (single machine) up to 400 kg/day (multiple machines installed in parallel).
Using multiple liquefiers in one system offers the advantage of redundancy.
The design concept of all Stirling systems is that all Cryogenerators will run independently from each other. Should one of the Cryogenerators be off-line, the liquefaction capacity of the other machines remains available.
A Stirling Cryogenics LH2 system will include all necessary internal piping, instrumentation, a transfer vessel and system control. All systems are built according ATEX or other relevant classification coding.
Optionally, catalytic ortho-para conversion, containerization and GH2 inlet gas purification can be offered.
Alternatively, Stirling Cryogenerators can be supplied as modules to a system integrator building the total system.
Liquid Hydrogen Boil-Off Management
The two-stage Stirling Cryogenerator can also be used as a re-liquefier for boil-off gas coming from a storage tank, preventing the blow-off of evaporated LH2. The Stirling system can handle 12 kg/day smallest to 50 kg/day for our largest single Cryogenerator. By putting the Cryogenerators in parallel in a system, a bigger capacity can be reached.
This can be achieved either by direct re-liquefaction of the cold gas, or by a cold He loop transporting cooling power from the Cryogenerator into the storage tank and therewith subcooling the LH2.