Liquid hydrogen production device

Abstract

A device (HS) is provided with a refrigeration cycle unit (R) and a liquid hydrogen generation unit (P) for generating liquid hydrogen by cooling high-pressure raw material hydrogen by means of the refrigeration cycle unit (R) and by adiabatically expanding said raw material hydrogen by means of a Joule-Thomson valve ( 12 ). A first and second heat exchanger (E 1 , E 2 ) are disposed along the refrigeration cycle unit (R) and the liquid hydrogen generation unit (P). The device (HS) is provided with a mechanism for generating liquid hydrogen by re-liquefying the boil-off gas generated in a liquid hydrogen storage tank. The boil-off gas is introduced into a hydrogen circulation path ( 1 ) at a section at which circulating hydrogen having an extremely low temperature flows, and the excessive circulating hydrogen generated therefrom is discharged to a raw material hydrogen path ( 11 ) from a section at which the circulating hydrogen is at room temperature.

1 . An apparatus for producing liquid hydrogen comprising:
 a refrigeration cycle unit in which circulating hydrogen flows as a refrigerant;   a liquid hydrogen producing unit for producing the liquid hydrogen from gaseous hydrogen;   a boil-off gas supplying unit for supplying boil-off gas generated in a liquid hydrogen reservoir to said refrigeration cycle unit through a predetermined inlet portion in said refrigeration cycle unit; and   a circulating hydrogen discharge unit for discharging excessive circulating hydrogen resulting from the boil-off gas supplied to said refrigeration cycle unit by means of said boil-off gas supplying unit, to said liquid hydrogen producing unit through a predetermined outlet portion in said refrigeration cycle unit.   
     
     
         2 . The apparatus according to  claim 1 , wherein said refrigeration cycle unit comprises:
 a compressor for compressing the circulating hydrogen;   an expander for expanding the circulating hydrogen; and   at least one heat exchanger interposed between said compressor and said expander, said heat exchanger including a low-temperature heat exchanging element located at an upstream side of said compressor and a high-temperature heat exchanging element located at a downstream side of said compressor,   wherein said liquid hydrogen producing unit comprises:   a raw hydrogen passage, through which the gaseous hydrogen supplied from a raw hydrogen source, flows;   an expansion valve for expanding the gaseous hydrogen to produce the liquid hydrogen, the expansion valve being disposed at a downstream side of said raw hydrogen passage; and   at least one gaseous hydrogen cooler for cooling the gaseous hydrogen by heat exchange with said at least one heat exchanger of said refrigeration cycle unit,   wherein said inlet portion in said refrigeration cycle unit is disposed at a position located downstream of said expander and upstream of said compressor, and   wherein said outlet portion in said refrigeration cycle unit is disposed at a position located between the first low-temperature heat exchanging element in an upstream direction from said compressor and the first high-temperature heat exchanging element in a downstream direction from said compressor.   
     
     
         3 . The apparatus according to  claim 1 , wherein said inlet portion in said refrigeration cycle unit is composed of a plurality of inlet elements disposed depending on differences between the temperature of the circulating hydrogen in said refrigeration cycle unit and the temperature of the boil-off gas generated in said liquid hydrogen reservoir. 
     
     
         4 . The apparatus according to  claim 1 , wherein said outlet portion in said refrigeration cycle unit is disposed between said compressor and the first high-temperature heat exchanging element in a downstream direction from said compressor. 
     
     
         5 . The apparatus according to  claim 1 , wherein said expander is an expansion turbine. 
     
     
         6 . The apparatus according to  claim 1 , wherein said expansion valve is a Joule-Thomson valve. 
     
     
         7 . The apparatus according to  claim 1 , wherein said liquid hydrogen reservoir is a liquid hydrogen vessel of a liquid hydrogen transporting ship.