A series of new projects in recent years, have been carried out as lump sum turnkey installations or as E&E supplies with subsequent supervision of installation and commissioning. This fund of experience has been the basis for continuous developments of components. Key components include aluminium-plate heat exchangers and expansion turbines with dynamic gas bearings, developed and manufactured in our own production centres.
For small capacity liquefaction plants up to 1000 l/h, a closed helium circuit supplies the refrigeration necessary to cool the hydrogen. Pure hydrogen gas at approx. 20 bar is fed into the vacuum-insulated cold box and, after a certain degree of subcooling at the end of the refrigeration process, it expands through a Joule-Thomson valve into the storage tank. The helium refrigeration cycle and hydrogen liquefaction are completely separated. The main components of the system are the helium compressor with oil purification, the cold box with heat exchangers and helium expansion turbines, the liquid hydrogen tank and filling stations for transportable containers.
For liquefaction capacities over 1000 l/h, the necessary refrigeration for cooling and ortho-para conversion of the hydrogen is attained by means of a hydrogen Claude process, i.e. at the cold end of the process the H2 feed gas can be combined with the H2 of the refrigeration process.
The following main components are used for this process:
- piston compressors
- TED expansion turbines with dynamic gas bearing
- liquefier cold box
- liquid nitrogen precooling
For larger-scale systems, separate cold boxes can be considered – a first box for cooling the hydrogen from ambient temperature to 80 K and a second box from 80 down to 20 K.
Further system components such as:
- hydrogen purification
- raw gas compressors
- storage tanks and filling devices
are designed, supplied and installed by Linde Kryotechnik.