Methods and systems providing a process for cooling and liquefying a purified gaseous hydrogen feed stream to a liquid hydrogen stream that may be stored in a liquid hydrogen storage tank, as well as a system wherein ortho-hydrogen (o-H2) contained in the purified gaseous hydrogen feed stream may be converted to para-hydrogen (p-H2) through serial low-temperature catalytic converters along the cooling process from normal ambient temperature (300K) to the liquefied temperature about (20K) of the hydrogen.

A highly efficient refrigeration system and process for precooling/liquefaction of a hydrogen feed stream and method of turndown of such system is disclosed. The disclosed refrigeration system and associated methods employ a reverse Brayton refrigeration cycle using a nitrogen based refrigerant and a fully integrated three pinion bridge (BriM) machine operatively coupling at least two turbine/expanders and at least four nitrogen refrigerant compression stages. Turndown of the hydrogen precooling and liquefaction process requires removal of nitrogen refrigerant from the refrigeration recycle loop by retaining liquid nitrogen in the phase separator, which is sized to accommodate the bulk of the nitrogen refrigerant used in the refrigeration circuit.

Contemplated plants for flexible ethane recovery and rejection by allowing to switch the top reflux to the demethanizer from residue gas to the deethanizer overhead product and by controlling the flow ratio of feed gas to two different feed gas exchangers. Moreover, the pressure of the demethanizer is adjusted relative to the deethanizer pressure for control of the ethane recovery and rejection.

The invention relates to an installation for producing liquefied hydrogen having a gaseous hydrogen generator configured to produce gaseous hydrogen, a liquefier, a supply duct connecting a gaseous hydrogen outlet of the gaseous hydrogen generator to an inlet of the liquefier, the liquefier having a refrigerator having a cycle circuit configured to provide cooling power and cool the gaseous hydrogen from the supply duct with a view to the liquefaction thereof, the installation having at least one compressor for the gaseous hydrogen produced by the gaseous hydrogen generator and a buffer store configured to store the compressed gaseous hydrogen between the gaseous hydrogen generator and the liquefier, the buffer store being connected to the supply duct via a set of bypass duct(s), i.e. the buffer store and the liquefier are connected in parallel to the gaseous hydrogen outlet of the gaseous hydrogen generator.

Methods and systems providing a process for cooling and liquefying a purified gaseous hydrogen feed stream to a liquid hydrogen stream that may be stored in a liquid hydrogen storage tank, as well as a system wherein ortho-hydrogen (o-H2) contained in the purified gaseous hydrogen feed stream may be converted to para-hydrogen (p-H2) through serial low-temperature catalytic converters along the cooling process from normal ambient temperature (300K) to the liquefied temperature about (20K) of the hydrogen.

Methods and systems providing a process for cooling and liquefying a purified gaseous hydrogen feed stream to a liquid hydrogen stream that may be stored in a liquid hydrogen storage tank, as well as a system wherein ortho-hydrogen (o-H2) contained in the purified gaseous hydrogen feed stream may be converted to para-hydrogen (p-H2) through serial low-temperature catalytic converters along with cooling process from normal ambient temperature (300K) to the liquefied temperature (about 20K) of the hydrogen.