The present invention is a hydrogen cooling apparatus comprising: a air-cooled condenser disposed on a part of a first coolant passage so as to enable cooling of a first coolant by driving an air-cooling fan; a first heat exchanger enabling cooling of a second coolant by the first coolant, between another part of the first coolant passage and a part of a second coolant passage; and a second heat exchanger enabling cooling of hydrogen by the second coolant, between another part of the second coolant passage and a part of a hydrogen passage. A driving rotational speed of the air-cooling fan is inverter controlled in such a manner that a pressure of the first coolant from the air-cooled condenser to the first heat exchanger is maintained between 1.5 MPa and 1.7 MPa.

A vessel includes a heat exchanger for heat-exchanging compressed boil-off gas (hereinafter, referred to as first fluid) by using, as a refrigerant, the boil-off gas discharged from a storage tank, to cool the same; a main compression part for compressing a part of the boil-off gas discharged from the storage tank; a rest compression part provided in parallel to the main compression part so as to compress the other part of the boil-off gas discharged from the storage tank; and a decompression device for expanding the first fluid having been cooled by exchanging heat with the boil-off gas, which is discharged from the storage tank, in the heat exchanger. The first fluid is a flow in which the boil-off gas compressed by the main compression part and the boil-off gas compressed by the rest compression part join; or the boil-off gas compressed by the main compression part.

A ship includes: a boil-off gas heat exchanger installed on a downstream of a storage tank and heat-exchanges a compressed boil-off gas (a first fluid) by a boil-off gas discharged from the storage tank as a refrigerant, to cool the boil-off gas; a compressor installed on a downstream of the boil-off gas heat exchanger and compresses a part of the boil-off gas discharged from the storage tank; an extra compressor installed on a downstream of the boil-off gas heat exchanger and in parallel with the compressor and compresses the other part of the boil-off gas discharged from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid which is cooled by the boil-off gas heat exchanger; and a refrigerant decompressing device which expands a second fluid, which is sent to the refrigerant heat exchanger, and then sends the second fluid back to the refrigerant heat exchanger.

A ship including a liquefied gas storage tank includes: first and second compressors which compresse a boil-off gas discharged from a storage tank; a boost compressor which compresses one part of the boil-off gas that is compressed by at least any one of the first compressor and/or the second compressor; a first heat exchanger which heat exchanges the boil-off gas compressed by the boost compressor and the boil-off gas discharged from the storage tank; a refrigerant decompressing device which expands the other part of the boil-off gas that is compressed by at least any one of the first compressor and/or the second compressor; a second heat exchanger which cools, by a fluid expanded by the refrigerant decompressing device as a refrigerant; and an additional compressor which is compresses the refrigerant that passes through the refrigerant decompressing device and second heat exchanger.

A ship includes: a boil-off gas heat exchanger which is installed on a downstream of a storage tank and heat-exchanges a compressed boil-off gas (a first fluid) by a boil-off gas discharged from the storage tank as a refrigerant to cool the boil-off gas; a compressor installed on a downstream of the boil-off gas heat exchanger and compresses a part of the boil-off gas from the storage tank; an extra compressor which is installed on a downstream of the boil-off gas heat exchanger and in parallel with the compressor and compresses the other part of the boil-off gas from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid; and a refrigerant decompressing device which expands a second fluid, which is sent to the refrigerant heat exchanger, and then sends the second fluid back to the refrigerant heat exchanger.

A ship includes: a boil-off gas heat exchanger which heat-exchanges a compressed boil-off gas (a first fluid) by means of a boil-off gas discharged from the storage tank as a refrigerant; a compressor installed on the downstream of the boil-off gas heat exchanger and compressing a part of the boil-off gas discharged from the storage tank; first and second extra compressors provided in parallel with the compressor on the downstream of the boil-off gas heat exchanger and compressing the other part of the boil-off gas discharged from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid cooled by means of the boil-off gas heat exchanger; a refrigerant decompressing device which expands a second fluid, which has been sent to the refrigerant heat exchanger and cooled by means of the refrigerant heat exchanger, and then sending the expanded second fluid back to the refrigerant heat exchanger.

A ship including a storage tank for storing a liquefied gas includes: a boil-off gas (BOG) heat exchanger installed on a downstream of a storage tank and heat-exchanges a compressed BOG (a first fluid) by a BOG discharged from the storage tank as a refrigerant, to cool the BOG; a compressor installed on a downstream of the BOG heat exchanger and compresses a part of the BOG discharged from the storage tank; an extra compressor installed on a downstream of the BOG heat exchanger and in parallel with the compressor and compresses the other part of the BOG discharged from the storage tank; a refrigerant heat exchanger which additionally cools the first fluid cooled by the BOG heat exchanger; and a refrigerant decompressing device which expands a second fluid sent to the refrigerant heat exchanger, and then sends the second fluid back to the refrigerant heat exchanger.

A ship includes: an boil-off gas heat exchanger installed on a downstream of the storage tank such that compressed boil-off gas (first fluid) is made to exchange heat and cooled using boil-off gas discharged from the storage tank as a refrigerant; a compressor installed on a downstream of the boil-off gas heat exchanger so as to compress a part of the boil-off gas discharged from the storage tank; an extra compressor installed on a downstream of the boil-off gas heat exchanger in parallel with the compressor so as to compress the other part of the boil-off gas discharged from the storage tank; a refrigerant heat exchanger for additionally cooling the first fluid that is cooled by the boil-off gas heat exchanger; and a refrigerant decompressing device which expands the second fluid sent to the refrigerant heat exchanger and cooled by the refrigerant heat exchanger.

A system for reliquefying a boil off gas generated in a storage tank includes a first compressor compressing a partial amount (hereinafter, referred to as fluid a) of boil off gas discharged from the storage tank, a second compressor compressing another partial amount (hereinafter, referred to as fluid b) of boil off gas discharged from the storage tank, a second expanding unit expanding a partial amount (hereinafter, referred to as fluid c) of a flow formed as the fluid a and the fluid b join, a heat-exchanger cooling another partial amount (hereinafter, referred to as fluid d) of the flow formed as the fluid a and the fluid b join, and a first expanding unit expanding the fluid d cooled by the heat-exchanger, wherein the heat-exchanger heat-exchanges the fluid d with the fluid c as a coolant expanded by the second expanding unit to cool the fluid d.

A cryogenic energy storage system comprises at least one cryogenic fluid storage tank having an output; a primary conduit through which a stream of cryogenic fluid may flow from the output of the fluid storage tank to an exhaust; a pump within the primary conduit downstream of the output of the tank for pressurising the cryogenic fluid stream; evaporative means within the primary conduit downstream of the pump for vaporising the pressurised cryogenic fluid stream; at least one expansion stage within the primary conduit downstream of the evaporative means for expanding the vaporised cryogenic fluid stream and for extracting work therefrom; a secondary conduit configured to divert at least a portion of the cryogenic fluid stream from the primary conduit and reintroduce it to the fluid storage tank; and pressure control means within the secondary conduit for controlling the flow of the diverted cryogenic fluid stream and thereby controlling the pressure within the tank. The secondary conduit is coupled to the primary conduit downstream of one or more of the at least one expansion stages.