Plant and method for producing hydrogen at cryogenic temperature, in particular liquefied hydrogen, comprising: an electrolyzer having an oxygen outlet and a hydrogen outlet; a hydrogen circuit to be cooled, comprising an upstream end connected to the hydrogen outlet and a downstream end to be connected to a member for collecting cooled and/or liquefied hydrogen, the plant also comprising a set of heat exchanger(s) in heat exchange with the hydrogen circuit to be cooled, the plant further comprising at least one cooling device in heat exchange with at least a portion of the set of heat exchanger(s), the hydrogen circuit to be cooled comprising a system for expanding the hydrogen stream and at least one hydrogen compressor upstream of the hydrogen stream expansion system, the hydrogen stream expansion system comprising at least one expansion turbine, wherein said at least one expansion turbine and said at least one compressor are coupled to the same rotating shaft to transfer expansion work from the pressurized hydrogen stream to the compressor in order to compress the hydrogen stream upstream of the turbine.

One object of the present invention is to provide a natural gas liquefaction device which uses noncombustible gas as a refrigerant, and can reduce the power consumption a range of relatively low refrigerant pressure, and the present invention provides a natural gas liquefaction device including a compressor which is configured to compress a refrigerant containing noncombustible gas by a plurality of compression stages; a heat exchanger which is configured to cool and liquefy a natural gas to be a liquefied natural gas; a natural gas liquefaction line which is configured to introduce the natural gas into the heat exchanger and supply the liquefied natural gas to an outside; a first refrigerant line which is configured to introduce a refrigerant-1 passed through the compressor into the heat exchanger, and then further introduce the refrigerant-1 into a decompressor; a second refrigerant line which is configured to introduce the refrigerant-2 decompressed by the decompressor into the heat exchanger, and further introduce the refrigerant-2 into any one of a second compression stage and subsequent stages of the compressor; a third refrigerant line which is configured to be branched from the first refrigerant line and introduce at least a part of the refrigerant-1 into an expansion turbine; and a fourth refrigerant line which is configured to introduce the refrigerant-3 expanded by the expansion turbine into the heat exchanger, and further introduce the refrigerant-3 into a first compression stage of the plurality of compression stages provided in the compressor.

Systems and methods are described for increasing capacity and efficiency of a nitrogen refrigerant boil-off gas recovery system for a natural gas storage tank. Boil-off gas is condensed against two-phase nitrogen in a condensing heat exchanger having an inner vessel through which the boil-off gas flows and an outer vessel through which the two phase nitrogen flows. Logic controls maintain storage tank pressure and power consumption within preferred levels by adjusting the pressure of the two-phase nitrogen in the heat exchanger. Additional logic controls maintain the temperature difference between the nitrogen streams entering into and returning from the cold end of a second heat exchanger by controlling the position of an expansion valve on the return circuit.

The present invention relates to a refrigerant composition comprising neon and hydrogen. The present invention further relates to the use of the refrigerant composition in liquefying gaseous substances such as hydrogen or helium.

There is provided a system and method for producing liquefied natural gas (LNG). An exemplary method includes flowing a high-pressure stream of LNG through a first series of liquid turbines. The exemplary method also includes generating electricity by reducing the pressure of the high-pressure stream of LNG to form a low-pressure stream of LNG. The exemplary method additionally includes bypassing any one the liquid turbines that has a failure while continuing to produce electricity from the first series.

A system and method for increasing the efficiency of natural gas liquefaction processes by using a hybrid cooling system and method. More specifically, a system and method for converting a transcritical precooling refrigeration process to a subcritical process. In one embodiment, the refrigerant is cooled to sub-critical temperature using an economizer. In another embodiment, the refrigerant is cooled to a sub-critical temperature using an auxiliary heat exchanger. Optionally, the economizer or auxiliary heat exchanger can be bypassed when ambient temperatures are sufficiently low to cool the refrigerant to a sub-critical temperature. In another embodiment, the refrigerant is isentropically expanded.

There is provided a system and method for producing liquefied natural gas (LNG). An exemplary method includes flowing a high-pressure stream of LNG through a first series of liquid turbines. The exemplary method also includes generating electricity by reducing the pressure of the high-pressure stream of LNG to form a low-pressure stream of LNG. The exemplary method additionally includes bypassing any one the liquid turbines that has a failure while continuing to produce electricity from the first series.

A method including, compressing a first hydrogen stream, and expanding a portion to produce a hydrogen refrigeration stream, cooling a second hydrogen stream thereby producing a cool hydrogen stream, wherein at least a portion of the refrigeration is provided by a nitrogen refrigeration stream, further cooling at least a portion of the cool hydrogen stream thereby producing a cold hydrogen stream, and a warm hydrogen refrigeration stream wherein at least a portion of the refrigeration is provided by the hydrogen refrigeration stream, compressing the warm hydrogen refrigeration stream, mixing the balance of the compressed first hydrogen stream with a high-pressure gaseous nitrogen stream to form an ammonia synthesis gas stream, and wherein the first hydrogen stream and the warm hydrogen refrigeration stream are compressed in the same compressor.

A method of liquefying hydrogen, including dividing a hydrogen stream into at least a first fraction and a second fraction, introducing the first fraction into a refrigeration cycle of a hydrogen liquefaction unit, thereby liquefying a product hydrogen stream, withdrawing one or more warm hydrogen stream(s) from the hydrogen liquefaction unit, and returning the one or more warm hydrogen stream to the hydrogen stream, wherein the second fraction is combined with a high-pressure nitrogen stream to form an ammonia synthesis gas stream.

A liquefaction system for removing heat from a process fluid to condense the process fluid, the liquefaction system including a primary heat exchanger configured to remove heat from the process fluid via heat exchange with one or more refrigerants, a compressor configured to compress the one or more refrigerants, a first secondary heat exchanger configured to remove heat from the one or more refrigerants via heat exchange with ambient air, and a second secondary heat exchanger configured to remove heat from the one or more refrigerants via heat exchange with ambient water.