Cryogenic fluid production facility

Abstract

Installation for the production of a cryogenic fluid, comprising: a circuit of gas to be cooled, a set of heat exchangers in heat exchange with the circuit of gas to be cooled, a cooling device arranged to cool the circuit of gas to be cooled by heat exchange with a heat exchanger, a bypass line for the gas to be cooled, arranged to divert the gas to be cooled from the circuit of gas to be cooled to a compression unit arranged to compress the diverted gas to be cooled, a reinjection line for the gas thus treated, said reinjection line being arranged to reinject the gas thus treated into the circuit of gas to be cooled, the installation being arranged so that at least 50% of the flow of gas to be cooled is diverted to the bypass line during a start-up phase of said installation. Figure for the abbreviation: Fig. 1

Description

Title of the invention: Installation for the production of a cryogenic fluid

[0001] The field of the present invention is that of an installation for the production of a cryogenic fluid, in particular liquefied hydrogen. The present invention also relates to a method for producing a cryogenic fluid, in particular liquefied hydrogen.

[0002] Hydrogen is an energy carrier that plays an increasing role in the decarbonization of various sectors, particularly transport and industry. Hydrogen liquefaction makes it possible to store hydrogen and transport it over long distances.

[0003] The hydrogen liquefier comprises several refrigeration cycles, including in particular one or more pre-cooling cycles and a cooling cycle. The refrigerant circulating in the cooling cycle is either helium, hydrogen, or a helium / neon mixture. Cryogenic purification is carried out during the hydrogen liquefaction.

[0004] It is becoming increasingly important not to release hydrogen into the atmosphere for the following reasons: - The hydrogen molecule is expensive, - Hydrogen could contribute to the greenhouse effect and global warming, Releasing hydrogen into the atmosphere without burning it in a stack creates a flammable cloud. If this cloud ignites (e.g., in the presence of an energy source such as snowfall, thunderstorms, a hotspot, or radiation), it can lead to safety issues (delayed ignition causing a pressure surge), noise, and radiation. This can create acceptance constraints in the vicinity of the liquefier due to the noise generated, requiring sufficient distances between equipment and necessitating directing the hydrogen release to a high altitude and / or burning it in a flare.

[0005] Hydrogen releases into the atmosphere for a liquefier can be of different kinds such as exceptional releases (e.g. overpressure control), regular releases (e.g. hydrogen purification regeneration) or releases related to the start-up of the unit, in particular the release of hydrogen to be liquefied until it is sufficiently cooled and liquefied to be sent to cryogenic storage.

[0006] As described in documents JP2020024067, FR3108390, US20230147955 and GB822122, Hydrogen, 4. Liquefaction (Ullmann's Encyclopedia of Industrial Chemistry, 2013) and Kuendig et al, (Large scale hydrogen liquefaction in combination with LNG re-gasification), it is known to use bypass conduits, also called bypasses, between the hydrogen circuit to be cooled and the cooling or pre-cooling cycles so as to circulate the gas to be cooled towards the cooling cycle or vice versa.

[0007] Today it is important to reduce the safety risks and costs associated with hydrogen releases, particularly at the start of the liquefaction process for liquefiers that may restart frequently.

[0008] The present invention thus aims to limit hydrogen emissions into the atmosphere, particularly during the start-up of the liquefier.

[0009] The object of the invention relates to an installation for the production of a cryogenic fluid, in particular liquefied hydrogen, comprising: - a circuit for the gas to be cooled having an upstream end intended to be connected to a gas source and a downstream end intended to be connected to at least one receiving system, for example a cryogenic storage facility, - a set of heat exchangers in thermal exchange with the gas circuit to be cooled, - a cooling device arranged to cool the gas circuit to be cooled by heat exchange with at least one heat exchanger, the cooling device comprising a cooling circuit with a refrigeration cycle of a cycle gas, the cycle gas being chosen in particular from hydrogen or helium, - at least one bypass line for the gas to be cooled, said bypass line being arranged to divert the gas to be cooled from the gas circuit to be cooled towards at least one compression unit arranged to compress at least the diverted gas to be cooled and possibly towards a heating unit arranged to heat at least the diverted gas, said bypass line being arranged in particular upstream of the receiving system in the direction of flow of the gas to be cooled, - at least one reinjection line for the gas thus treated, said reinjection line being arranged to reinject the gas thus treated into the gas circuit to be cooled.

[0010] According to one aspect of the invention, the heating element is arranged upstream or downstream of the compression element in the direction of flow of the diverted gas.

[0011] According to one aspect of the invention, the installation comprises at least one expansion member arranged to expand the diverted gas downstream of the compression member and in upstream of the treated gas reinjection line in the direction of flow of the diverted gas.

[0012] According to one aspect of the invention, at least one expansion member is a Joule-Thomson type valve.

[0013] According to one aspect of the invention, the installation comprises a set of expansion devices arranged to expand the diverted gas downstream of the compression device and upstream of the treated gas reinjection line in the direction of flow of the diverted gas, the set of expansion devices comprising turbines and / or Joule-Thomson type valves.

[0014] The installation according to the invention makes it possible to limit the release into the air of gas to be cooled, in particular hydrogen, by using it in the installation when necessary, in particular during a start-up stage of the installation.

[0015] By treated gas, we mean the gas to be cooled diverted, possibly heated, compressed and possibly expanded.

[0016] In one aspect according to the invention, the installation is arranged so that at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably 100% of the flow of gas to be cooled is diverted to the bypass line during a start-up phase of said installation.

[0017] In one aspect according to the invention, the installation comprises: - a pre-cooling device comprising a pre-cooling circuit in heat exchange with at least a first part of the heat exchanger assembly and configured to pre-cool the gas circuit to be cooled to a first determined temperature, in particular a temperature close to 80 Kelvin, - the cooling device comprising the cooling circuit in heat exchange with at least a second part of the heat exchanger assembly(ies) and configured to cool the gas circuit to be cooled to a second determined temperature lower than the first temperature, in particular a temperature close to 20 Kelvin, - at least one first cold box in which is placed: • the first part of the heat exchanger assembly for cooling the gas circuit to be cooled to the first determined temperature, • a cryogenic purifier, in particular of the TSA type, arranged on the circuit of gas to be cooled, and possibly a regeneration circuit configured to regenerate the cryogenic purifier, and disposed at least partially in the first box on the circuit of gas to be cooled, • possibly a catalytic device arranged on the gas circuit to be cooled, - at least one second cold box, separate from the first cold box, and in which is arranged the second part of the heat exchanger assembly(ies) to cool the gas circuit to be cooled to the second determined temperature lower than the first temperature.

[0018] In one aspect according to the invention, the installation comprises a plurality of first cold boxes arranged in parallel with respect to each other, and / or the installation comprises a plurality of second cold boxes arranged in parallel with respect to each other.

[0019] In one aspect according to the invention, the first cold box is arranged upstream of the second cold box in the direction of flow of the gas to be cooled in the circuit of gas to be cooled.

[0020] By start-up phase of the installation, it is understood that the phase between the start-up of the installation and the moment at which the temperature of the gas to be cooled measured in the circuit of the gas to be cooled in the second cold box downstream of the second set of heat exchangers in the direction of circulation of the gas to be cooled is at a predetermined temperature between 20 Kelvin and 80 Kelvin, preferably between 20 Kelvin and 40 Kelvin.

[0021] In other words, as long as the installation has not completed its start-up phase and therefore the gas to be cooled, here hydrogen, has not reached the predetermined temperature, said gas to be cooled is recycled within the installation, at least in part, instead of being released into the atmosphere. In this way, the costs and pollution associated with hydrogen releases during the installation's start-up phase are reduced.

[0022] In one aspect according to the invention, the installation includes a temperature measuring sensor, preferably of the resistive type, configured to measure the temperature of the gas to be cooled in the gas circuit to be cooled in the second cold box downstream of the second set of heat exchangers in the direction of circulation of the gas to be cooled.

[0023] In one aspect according to the invention, the bypass line is arranged to divert the gas to be cooled towards at least one compression member as a function of the temperature of the gas to be cooled measured by the temperature sensor.

[0024] In one aspect according to the invention, the installation comprises at least two bypass pipes, in particular two, in particular three, in particular four bypass pipes.

[0025] In one aspect according to the invention, the installation comprises at least two bypass lines, the two bypass lines being arranged to divert the gas to be cooled towards a compression element for said gas and optionally towards a device for heating, the two bypass pipes being arranged to divert the gas to different locations in the installation.

[0026] In one aspect according to the invention, the installation comprises at least two bypass pipes, one of the bypass pipes being connected by one of its ends to the circuit of gas to be cooled downstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in particular in the second cold box, and by its other end to a circuit comprising at least one compression element arranged to compress at least said diverted gas.

[0027] In one aspect according to the invention, the bypass line includes at least one gas flow control device, in particular a valve, said gas flow control device being arranged to control the flow of gas to be cooled circulating in the bypass line.

[0028] In one aspect according to the invention, the gas flow control device is arranged so as to allow at least a portion of the gas to be cooled to pass into the bypass line in the open position and to prevent the gas to be cooled from passing into the bypass line in the closed position. Thus, in the open position, the gas to be cooled is diverted to at least one compression element, and in the closed position the gas to be cooled continues to flow in the gas circuit, for example, to the downstream end of the gas circuit.

[0029] In one aspect according to the invention, the bypass line comprises at least two gas flow control devices for the gas to be cooled, said gas flow control devices for the gas to be cooled being mounted in parallel with each other.

[0030] In one aspect according to the invention, the at least two gas flow control elements to be cooled are of different sizes.

[0031] In one aspect according to the invention, one of the two gas flow control devices is arranged to control the flow of gas to be cooled in the bypass line during the start-up phase of the installation, while the other control device is arranged to control the flow of gas to be cooled once the installation is started. Thus, one of the gas flow control devices allows the flow of gas to be diverted into the bypass line during the start-up phase of the installation to be controlled in order to limit the release of gas to be cooled into the atmosphere, and the other gas flow control device allows the flow of gas to be cooled to be controlled when the installation is started, i.e.that the gas to be cooled has reached the predetermined temperature, so as to compensate for example for the emissions of cycle gases from the cooling circuit when the installation is running (for example in case of leaks).

[0032] In one aspect according to the invention, the gas flow control device is arranged so that, in the open position, at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably 100% of the gas flow to be cooled passes through the bypass line during the start-up phase of the installation.

[0033] In one aspect according to the invention, the flow control element for the gas to be cooled is a controlled-opening valve, for example, a controlled-opening Joule-Thomson type valve. The advantage of such a valve is that it can gradually increase the flow rate circulating in the bypass line until the temperature of the fluid to be cooled is sufficiently low for the valve to be closed, so that the gas to be cooled no longer circulates in the bypass line and is sent to the downstream end of the gas circuit to be cooled and then to the cooled gas receiving system.

[0034] In one aspect according to the invention, the gas flow control element is configured to control the flow rate of the gas to be cooled in the bypass line as a function of the temperature of the gas to be cooled measured by the temperature sensor. Thus, when the temperature of the gas to be cooled is higher than the predetermined temperature, the gas flow control element is in the open position so as to allow the gas to be cooled to pass through the bypass line, and when the temperature of the gas to be cooled measured by the temperature sensor reaches the predetermined temperature, the gas flow control element moves to the closed position so as to prevent the gas to be cooled from passing through the bypass line.

[0035] In one aspect according to the invention, the gas flow control device is arranged to allow at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably 100% of the gas flow to be cooled to pass through the bypass line when the temperature of the gas to be cooled measured by the temperature sensor in the gas circuit to be cooled is above the predetermined temperature.

[0036] In one aspect according to the invention, the predetermined temperature is between 20 Kelvin and 80 Kelvin, preferably between 20 Kelvin and 40 Kelvin.

[0037] In one aspect of the invention, at least one reinjection line is arranged to reinject at least the treated gas into the gas circuit to be cooled during the start-up phase of the installation.

[0038] Thus, once the installation is running, i.e. the gas to be cooled has reached the predetermined temperature measured in the circuit of gas to be cooled downstream of the second cold box, the reinjection line no longer reinjects gas into the circuit of gas to be cooled.

[0039] In one aspect according to the invention, the installation includes a treated gas flow control device arranged to control the treated gas flow in the re- injection.

[0040] In one aspect according to the invention, the treated gas flow control device is arranged so that, in the open position, it allows the treated gas to pass into the reinjection line, and in the closed position, it prevents the treated gas from passing into the reinjection line. Thus, in the open position, the treated gas can flow into the reinjection line and return to the gas circuit to be cooled, and in the closed position, the treated gas cannot flow into the reinjection line and return to the gas circuit to be cooled.

[0041] In one aspect according to the invention, the treated gas flow control device is arranged to control the passage of the treated gas in the reinjection line as a function of the temperature of the gas to be cooled measured by the temperature sensor.

[0042] In one aspect according to the invention, the reinjection line is connected by one of its ends to the gas circuit to be cooled and by its other end to the cooling circuit downstream of a cycle gas compression element.

[0043] Alternatively, the reinjection line is connected at one end to the gas circuit to be cooled and at its other end to a third circuit downstream of a third compression unit.

[0044] In one aspect according to the invention, the cycle gas of the cooling circuit comprises hydrogen.

[0045] In one aspect according to the invention, the cycle gas cooling circuit of the cooling device includes at least one cycle gas compression element.

[0046] In one aspect according to the invention, the cooling circuit comprises at least two cycle gas compression elements, for example, a low-pressure compression element and a high-pressure compression element. A low-pressure compression element is understood here to be a compressor arranged to compress a gas from a pressure of approximately 1 bar to a pressure between 5 and 10 bar (absolute bar). A high-pressure compression element is understood here to be a compressor arranged to compress a gas from a pressure between 5 and 10 bar to a pressure between 40 and 80 bar.

[0047] In one aspect according to the invention, the low pressure compression member and the high pressure compression member are mounted in series on the cooling circuit.

[0048] In one aspect according to the invention, the cooling circuit includes at least one cycle gas heating element arranged to heat at least the cycle gas before it passes into the compression element.

[0049] In one aspect of the invention, the first part of the heat exchanger assembly comprises the cycle gas heating element of the cooling circuit.

[0050] In one aspect according to the invention, the cycle gas heating element is arranged in upstream of at least one cycle gas compression device in the direction of cycle gas flow in the cooling circuit.

[0051] In one aspect according to the invention, the cooling circuit includes at least one compressed cycle gas expansion device arranged to expand at least said compressed cycle gas.

[0052] In one aspect of the invention, the cooling circuit includes at least one expansion member arranged to expand the gas to an intermediate pressure, in particular an intermediate pressure of between 5 and 10 bara, and at least one expansion member arranged to expand the gas to a low pressure, in particular a low pressure of between 1 and 2 bara.

[0053] In one aspect according to the invention, the expansion member arranged to expand the gas to an intermediate pressure is disposed on a bypass line of at least one expansion member arranged to expand the cycle gas to low pressure, said bypass line being arranged in the cooling circuit. In other words, when the cycle gas flows in the bypass line, the cycle gas is expanded by the intermediate pressure expansion member, and when the cycle gas does not flow in the bypass line, the cycle gas is expanded by the low pressure expansion member.

[0054] In one aspect of the invention, the medium pressure expansion device comprises at least one turbine.

[0055] In one aspect of the invention, the low pressure expansion member comprises at least one Joule-Thomson effect valve.

[0056] In one aspect according to the invention, the bypass line is arranged to return the expanded cycle gas to at least one medium pressure expansion member upstream of a high pressure compression member, preferably between a low pressure compression member and a high pressure compression member.

[0057] In one aspect according to the invention, the cooling circuit is arranged to circulate a portion of the cycle gas in the bypass line so that said portion of the gas passes through at least one medium pressure expansion member and another portion of the cycle gas to the low pressure expansion member.

[0058] In one aspect of the invention, the cooling circuit is arranged so that the portion of cycle gas passing through the medium pressure expansion member is then directed upstream of a high pressure compression member, preferably between a low pressure compression member and a high pressure compression member, and the other portion of cycle gas passing through at least one low pressure expansion member is then directed upstream of a low pressure compression member of the cooling circuit.

[0059] In one aspect according to the invention, the bypass conduit comprises two ex- terminals, one end of which is connected to the gas circuit to be cooled and the other end is connected to the cooling circuit, in particular upstream of a gas cycle compression unit.

[0060] In one aspect according to the invention, the bypass line is arranged to divert the gas to be cooled towards at least one gas cycle compression member of the cooling circuit. In this case, the gas cycle compression member of the cooling circuit is arranged to compress the cycle gas and the diverted gas to be cooled.

[0061] In one aspect according to the invention, the installation comprises at least two bypass lines, one of the bypass lines being connected at one end to the gas circuit to be cooled downstream of the second part of the heat exchanger assembly in the direction of gas flow, particularly in the second cold box, and at its other end to the cooling circuit, particularly in the second cold box, particularly downstream of the expansion valve of the cooling circuit. This bypass line allows, in particular, the second cold box to be cooled so that it reaches its operating temperature of between 40 Kelvin and 20 Kelvin during the start-up phase of the installation.

[0062] In one aspect according to the invention, the bypass pipe is arranged to divert the gas to be cooled towards the cycle gas heating element of the cooling circuit, in particular upstream of at least one heating element of the cooling circuit. In other words, the bypass element is arranged to divert the gas to be cooled before its compression in the cycle gas compression element.

[0063] In one aspect according to the invention, the heating element of the cooling circuit is arranged to heat the gas to be cooled diverted by the bypass line of the gas to be cooled before its compression in at least one gas cycle compression element of the cooling circuit.

[0064] In one aspect according to the invention, the installation includes at least one bypass pipe comprising one end connected to the circuit of gas to be cooled downstream of the first part of the exchangers of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in particular in the first cold box, and another end connected to the cooling circuit.

[0065] In one aspect according to the invention, the installation includes at least one bypass pipe comprising one end connected to the circuit of gas to be cooled downstream of the cryogenic purifier in the direction of circulation of the gas to be cooled, in particular in the first cold box, and another end connected to the cooling circuit.

[0066] In one aspect according to the invention, the installation comprises at least one bypass pipe comprising one end connected to the circuit of gas to be cooled upstream of the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box, and another end connected to the cooling circuit. dissement.

[0067] In one aspect according to the invention, the installation includes at least one bypass pipe comprising one end connected to the gas circuit to be cooled downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of flow of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box and another end connected to the cooling circuit.

[0068] In one aspect according to the invention, the installation includes at least one bypass pipe comprising one end connected to the gas circuit to be cooled downstream of the first part of the heat exchanger assembly and upstream of the cryogenic purifier in the direction of circulation of the gas to be cooled, in other words between the first part of the heat exchanger assembly and the cryogenic purifier, in particular in the first cold box and another end connected to the cooling circuit.

[0069] In one aspect according to the invention, the installation includes at least one bypass pipe comprising one end connected to the gas circuit to be cooled upstream of the first part of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular upstream of the first cold box, and another end connected to the cooling circuit.

[0070] In one aspect according to the invention, the installation includes at least one bypass pipe comprising one end connected to the gas circuit to be cooled downstream of the second part of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box, and another end connected to the cooling circuit.

[0071] In one aspect according to the invention, the end of the bypass pipe connected to the cooling circuit is connected to said cooling circuit upstream of at least one compression member in the direction of circulation of the cycle gas of the cooling circuit.

[0072] In one aspect according to the invention, the installation comprises at least one bypass line having one end connected to the circuit of the gas to be cooled downstream of the first part of the heat exchanger assembly and the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box, and another end connected to the cooling circuit upstream of at least one compression unit in the direction of flow of the cycle gas of the cooling circuit. In this way, the gas to be cooled is diverted after its purification in the cryogenic purifier and arrives sufficiently pure at the compression unit of the cycle gas.

[0073] In one aspect according to the invention, the installation includes a treated gas reinjection line, said reinjection line comprising two ends, one of its ends being connected to the cooling circuit downstream of the compression member in the direction of circulation of the cycle gas of the cooling circuit, the other end being connected to the circuit of gas to be cooled upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box in the direction of circulation of the gas to be cooled.

[0074] In one aspect according to the invention, the installation includes at least one bypass pipe, one end of which is connected to the gas circuit to be cooled upstream of the first part of the heat exchanger assembly, in particular in the first cold box in the direction of flow of the gas to be cooled, the other end of the bypass pipe is connected to the cooling circuit upstream of at least one compression element in the direction of flow of the cycle gas.

[0075] This embodiment is particularly advantageous when the cryogenic purifier is not yet at a sufficiently cold temperature to allow it to perform its function and the source of gas to be cooled is pure.

[0076] In one aspect according to the invention, the installation includes a treated gas reinjection line, said reinjection line comprising two ends, one of its ends being connected to the cooling circuit downstream of the compression member in the direction of flow of the fluid gas, the other end being connected to the gas circuit to be cooled upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box in the direction of flow of the gas to be cooled.

[0077] In one aspect according to the invention, the installation includes at least one bypass pipe, one end of which is connected to the gas circuit to be cooled downstream of the first part of the heat exchanger assembly and the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box, the other end of the bypass pipe being connected to the cooling circuit upstream of at least one compression element in the direction of flow of the cycle gas.

[0078] In one aspect according to the invention, the installation includes a treated gas reinjection line, said reinjection line comprising two ends, one of its ends being connected to the cooling circuit downstream of the compression member in the first cold box in the direction of cycle gas flow, the other end being connected to the gas circuit to be cooled downstream of the first part of the heat exchanger assembly and the cryogenic purifier in the direction of gas flow to be cooled, in particular in the first cold box.

[0079] In one aspect according to the invention, the installation comprises at least one conduit of bypass, one end of which is connected to the gas circuit to be cooled downstream of the first part of the assembly of exchangers and the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box, the other end of the bypass pipe being connected to the cooling circuit upstream of at least one compression unit in the direction of flow of the cycle gas.

[0080] In one aspect according to the invention, the installation includes a treated gas reinjection line, said reinjection line having two ends, one of its ends being connected to the cooling circuit downstream of the compression member in the direction of cycle gas flow, the other end being connected to the gas circuit to be cooled downstream of the first part of the heat exchanger assembly and upstream of the cryogenic purifier in the direction of gas flow to be cooled, in other words between the first part of the heat exchanger assembly and the cryogenic purifier, in particular in the first cold box.

[0081] In one aspect according to the invention, the installation includes at least one bypass pipe, one end of which is connected to the circuit of gas to be cooled downstream of the first part of the assembly of exchangers and the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box, the other end of the bypass pipe being connected to the cooling circuit upstream of a low-pressure compression element in the first cold box in the direction of flow of the cycle gas.

[0082] In one aspect according to the invention, the installation includes a treated gas reinjection line, said reinjection line having two ends, one end being connected to the cooling circuit between the low-pressure compression unit and the high-pressure compression unit in the direction of cycle gas flow, the other end being connected to the gas circuit to be cooled upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box in the direction of gas flow to be cooled. This is particularly advantageous when the low-pressure compression unit is not lubricated or when the low-pressure compression unit has an oil removal system downstream of it, making it possible to achieve less than 50 ppb by mass of oil in the hydrogen upstream of the end of the reinjection line; indeed, this is an energy-efficient embodiment.

[0083] In one aspect according to the invention, the installation includes at least one bypass pipe, one end of which is connected to the circuit of gas to be cooled downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, Specifically, in the first cold box, the other end of the bypass line is connected to the cooling circuit between a medium-pressure expansion valve and a high-pressure compression valve for the cryogenic cycle gas. In other words, the bypass line is connected to the cooling circuit on the bypass line of the cooling circuit downstream of the medium-pressure expansion valve.

[0084] In one aspect according to the invention, the installation comprises at least two bypass lines, preferably at least three bypass lines, one of the bypass lines being connected by one of its ends to the gas circuit to be cooled, one end of which is connected to the gas circuit to be cooled downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box, the other end of the bypass line being connected to the cooling circuit between the low pressure expansion member and the low pressure compression member of the cycle gas.

[0085] In one aspect according to the invention, the installation comprises at least two, preferably at least three, preferably at least four bypass lines, one of the bypass lines being connected by one of its ends to the gas circuit to be cooled, one end of which is connected to the gas circuit to be cooled downstream of the second part of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box, the other end of the bypass line being connected to the cooling circuit downstream of a medium pressure expansion member and upstream of at least one high pressure compression member of the cooling circuit, in particular in the second cold box, in the direction of flow of the cycle gas.In other words, the fourth bypass line is connected to the cooling circuit on the cooling circuit bypass between the medium pressure expansion unit and the high pressure compression unit in the second cold box.

[0086] In one aspect according to the invention, the installation includes a treated gas reinjection line, said reinjection line comprising two ends, one of its ends being connected to the cooling circuit downstream of the high-pressure compression unit in the direction of cycle gas flow, the other end being connected to the gas circuit to be cooled upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box.

[0087] The compression elements can be, for example, positive displacement compressors (of screw and / or piston technology) that are dry or oil-lubricated. In the case of lubricated compressors, an oil removal system allows for The oil mixed with the gas passing through the compressor unit is removed to prevent the oil from freezing in the heat exchangers or being reinjected into the gas circuit to be cooled via at least one reinjection line. The oil removal system associated with the high-pressure compressor unit removes sufficient oil to avoid these oil contamination problems. Thus, in this embodiment, the oil potentially used in the compressors is sufficiently removed to allow the treated gas to be reinjected into the gas circuit to be cooled upstream of the cryogenic purifier.

[0088] In one aspect according to the invention, the installation for the production of a cryogenic fluid, in particular liquefied hydrogen, comprises: - a circuit for the gas to be cooled having an upstream end intended to be connected to a gas source and a downstream end intended to be connected to at least one receiving system, for example a cryogenic storage facility, - a set of heat exchangers in thermal exchange with the gas circuit to be cooled, - a cooling device arranged to cool the gas circuit to be cooled by heat exchange with at least one heat exchanger, the cooling device comprising a cooling circuit with a refrigeration cycle of a cycle gas, the cycle gas comprising in particular hydrogen or helium, - at least one bypass line for the gas to be cooled, said bypass line being arranged to divert the gas to be cooled from the gas circuit to a third circuit comprising at least one third compression unit arranged to compress the diverted gas and / or a third heating unit arranged to heat the diverted gas, the third circuit being separate from the cooling circuit, - at least one reinjection line for the gas thus treated, said reinjection line being arranged to reinject the gas thus treated into the gas circuit to be cooled.

[0089] In one aspect according to the invention, the third circuit is separate from the gas circuit to be cooled.

[0090] In one aspect of the invention, the third circuit is separate from the pre-cooling circuit

[0091] In one aspect according to the invention, the cooling circuit cycle gas does not circulate in the third circuit. In other words, the third compression element is arranged to compress a gas or a mixture of gases distinct from the cooling circuit cycle gas and whose composition may be identical or different from that of the cooling circuit cycle gas, and / or the third heating element is arranged to heating a gas or a mixture of gases different from the cycle gas of the cooling circuit.

[0092] In one aspect according to the invention, the third circuit is connected to the cooling circuit upstream of the gas cycle compression element of the cooling circuit.

[0093] In one aspect according to the invention, the cooling device does not include the third circuit. In other words, the third circuit is not part of the cooling circuit.

[0094] In one aspect according to the invention, the bypass pipe is arranged to divert the gas to be cooled successively to a third heating element separate from the cycle gas heating element and then to at least one cycle gas compression element of the cooling circuit.

[0095] In one aspect according to the invention, the installation includes at least one bypass pipe, one end of which is connected to the circuit of gas to be cooled downstream of the first part of the heat exchanger assembly and the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box, and the other end is connected to the third circuit upstream of at least one third heating element and / or at least one third compression element in the direction of flow of the diverted gas.

[0096] In one aspect according to the invention, the installation includes at least one bypass pipe, one end of which is connected to the circuit of gas to be cooled downstream of the first part of the heat exchanger assembly and the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box, and the other end is connected to the third circuit upstream of at least one third heating element and / or third compression element in the direction of flow of the diverted gas.

[0097] In one aspect according to the invention, the bypass pipe is arranged to divert the gas to be cooled successively towards the third heating element and then towards the gas cycle compression element of the cooling circuit.

[0098] In one aspect according to the invention, the installation includes a treated gas reinjection line, said reinjection line comprising two ends, one of its ends being connected to the cooling circuit downstream of at least one cycle gas compression element of the cooling circuit in the direction of cycle gas flow, the other end being connected to the gas circuit to be cooled upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box without the direction of flow of the gas to be cooled.

[0099] In one aspect according to the invention, the installation comprises at least one conduit of branch, one end of which is connected to the gas circuit to be cooled downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of flow of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box, and its other end is connected upstream of a third compression element separate from at least one compression element of the cycle gas of the cooling circuit, the third compression element being in particular disposed on a third circuit separate from the cooling circuit.

[0100] In one aspect according to the invention, the third compression element is arranged to compress at least one vaporized gas, in particular from a cryogenic storage. This may be, for example, exhaust gas generated by the thermal inlets of the storage, known in English as Boil-Off Gas (BOG).

[0101] In one aspect according to the invention, the third circuit comprises at least one third heating element disposed downstream of the third compression element in the direction of flow of the gas to be cooled diverted in the third circuit.

[0102] Alternatively, the third heating element is arranged upstream of the third compression element in the direction of flow of the gas to be cooled diverted in the third circuit.

[0103] In one aspect according to the invention, the installation comprises at least two bypass pipes, one of the bypass pipes being connected by one of its ends to the circuit of gas to be cooled downstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in particular in the second cold box, and by its other end to the third circuit upstream of a third compression element and / or a third heating element.

[0104] In one aspect according to the invention, the installation comprises at least one reinjection line, said reinjection line being connected by one of its ends to the third circuit downstream of the third compression element in the direction of flow of the diverted gas in the third circuit, and possibly downstream of the third heating element, and the other end is connected to the circuit of gas to be cooled upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box in the direction of flow of the gas to be cooled.

[0105] The invention further relates to a method for liquefying a gas, in particular hydrogen, using a hydrogen liquefaction plant, said method comprising, during a start-up phase of said plant: - a step of supplying a gas to be cooled in a gas cooling circuit, - a cooling step for said gas circuit to be cooled, implemented by a cooling device comprising a cooling circuit with a refrigeration cycle of a cycle gas, in particular hydrogen, - at least one step of diverting said gas to be cooled through a pipeline diversion of said gas to be cooled to a compression unit arranged to compress the diverted gas, and possibly to a heating unit arranged to at least reheat said diverted gas, the heating step being able to be carried out before and / or after the compression of said gas, - a step of reinjection of the gas thus treated into the gas circuit to be cooled by a reinjection line of said treated gas.

[0106] Advantageously, the process according to the invention makes it possible to reduce the emission of hydrogen to be cooled, in particular during the start-up of the installation by diverting it so that it can be used.

[0107] In one aspect according to the invention, the process is implemented in an installation as described above.

[0108] In one aspect according to the invention, the method comprises: - A pre-cooling step implemented in a pre-cooling device comprising a pre-cooling circuit in heat exchange with at least a first part of the heat exchanger assembly and configured to pre-cool the gas circuit to be cooled to a first determined temperature, in particular a temperature close to 80 Kelvin, - The cooling step implemented by the cooling device comprising the cooling circuit in heat exchange with at least a second part of the heat exchanger assembly(ies) and configured to cool the gas circuit to be cooled to a second determined temperature lower than the first temperature, in particular a temperature close to 20 Kelvin.

[0109] According to one aspect of the invention, the method is implemented in an installation as described above comprising: - a first cold box in which is placed: - the first part of the heat exchanger assembly for cooling the gas circuit to be cooled to the first determined temperature, - a cryogenic purifier, in particular of the Temperature Swing Adsorption (TSA) type, arranged on the gas circuit to be cooled, and possibly a regeneration circuit configured to regenerate the cryogenic purifier, and disposed at least partially in the first box on the gas circuit to be cooled, - possibly a catalytic device arranged on the gas circuit to be cooled, - a second cold box, separate from the first cold box, and in which is arranged the second part of the heat exchanger assembly(ies) to cool the gas circuit to be cooled to the second determined temperature lower than the first temperature.

[0110] In one aspect according to the invention, the first cold box is arranged upstream of the second cold box in the direction of flow of the gas to be cooled in the circuit of gas to be cooled.

[0111] In one aspect according to the invention, the gas to be cooled circulating in the gas to be cooled circuit comes from the source of gas to be cooled, then it passes first into the first part of heat exchangers in the first cold box where it is pre-cooled, it then circulates in the cryogenic purifier in the first cold box where it is purified, then it circulates in the second part of heat exchangers in the second cold box where it is cooled before joining the receiving system where the cooled and liquefied gas is stored.

[0112] In one aspect according to the invention, the process is carried out during a start-up phase of the gas liquefaction plant. In other words, the process is integrated into a start-up phase of the liquefaction plant.

[0113] By start-up phase of the installation, it is understood that the phase between the start-up of the installation and the moment at which the temperature of the gas to be cooled measured in the circuit of the gas to be cooled in the second cold box downstream of the second set of heat exchangers in the direction of circulation of the gas to be cooled is at a predetermined temperature between 20 Kelvin and 80 Kelvin, preferably between 20 Kelvin and 40 Kelvin.

[0114] In one aspect according to the invention, during the step of diverting the gas to be cooled, at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably 100% of the flow of gas to be cooled is diverted to the bypass line during a start-up phase of the installation.

[0115] In other words, as long as the installation has not completed its start-up phase and therefore the gas to be cooled, in this case hydrogen, has not reached the predetermined temperature, said gas to be cooled is recycled within the installation, at least in part, instead of being released into the atmosphere. In this way, the costs and pollution associated with hydrogen releases during the installation's start-up phase are reduced.

[0116] In one aspect according to the invention, the method includes a step of measuring the temperature of the gas to be cooled in the gas circuit to be cooled in the second cold box downstream of the second part of the heat exchanger assembly in the direction of flow of the gas to be cooled.

[0117] In one aspect of the invention, the temperature measurement step is carried out by a temperature sensor.

[0118] In one aspect according to the invention, the step of diverting the gas to be cooled to at least one compression element is a function of the temperature measured by the temperature sensor.

[0119] In one aspect according to the invention, the method comprises at least two steps, in particular three, in particular four steps of diverting the gas to be cooled to each at least one compression element and possibly to at least one heating element.

[0120] In one aspect according to the invention, the process comprises at least two steps of diverting the gas to be cooled to each at least one compression element and optionally to at least one heating element, the steps of diverting the gas to be cooled being able to be carried out simultaneously or sequentially in different locations of the installation used for the implementation of the process.

[0121] In one aspect according to the invention, the method comprises at least one or two steps of diverting the gas to be cooled by separate gas-to-cooling bypass lines.

[0122] In one aspect of the invention, during one of the diversion steps, the gas to be cooled is diverted through one of the bypass lines of the circuit of gas to be cooled downstream of the second part of heat exchangers in the second cold box to at least one compression element.

[0123] In one aspect of the invention, during one of the diversion steps, the gas to be cooled is diverted through one of the bypass lines of the gas circuit to be cooled downstream of the second part of heat exchangers in the second cold box to at least one gas cycle compression element of the cooling circuit. Thus, the gas to be cooled is diverted to at least one compression element of the cooling circuit after having circulated in the second part of heat exchangers.

[0124] In one aspect according to the invention, the method includes a step of controlling the flow rate of gas to be cooled by a flow control device for the gas to be cooled circulating in the bypass pipe, said control device being arranged in particular on the bypass pipe.

[0125] In one aspect according to the invention, the step of controlling the flow rate of the gas to be cooled is carried out between the step of supplying the gas to be cooled to the circuit of the gas to be cooled and the step of diverting the gas to be cooled.

[0126] In one aspect according to the invention, during the step of controlling the flow rate of the gas to be cooled, at least a portion of the gas to be cooled passes into the bypass line when the gas flow control device is in the open position, and the gas to be cooled does not pass into the bypass line when the gas flow control device is in the closed position. Thus, in the open position, the gas to The cooled gas is diverted to at least one compression element, and in the closed position the gas to be cooled continues to circulate in the circuit of gas to be cooled, for example to the downstream end of the circuit of gas to be cooled.

[0127] In one aspect of the invention, the method comprises at least two steps for controlling the flow rate of the gas to be cooled, carried out by gas flow control devices of different sizes. For example, one of the two gas flow control devices is arranged to control the flow rate of the gas to be cooled in the bypass line during the start-up phase of the installation, and the other control device is arranged to control the flow rate of the gas to be cooled once the installation is started. Thus, one of the gas flow control devices allows control of the flow rate of the gas to be cooled diverted into the bypass line during the start-up phase of the installation so as to limit the release of the gas to be cooled into the atmosphere, and the other gas flow control device allows control of the flow rate of the gas to be cooled when the installation is started, i.e.that the gas to be cooled has reached the predetermined temperature, so as to compensate for example for the emissions of cycle gases from the cooling circuit when the installation is running (for example in case of leaks).

[0128] In one aspect according to the invention, during the step of controlling the flow rate of the gas to be cooled in the bypass line, the passage of the gas to be cooled in the bypass line is controlled according to the temperature of the gas to be cooled measured by the temperature sensor. Thus, when the temperature of the gas to be cooled is higher than the predetermined temperature, the gas flow control element is in the open position so as to allow the gas to be cooled to pass through the bypass line, and when the temperature of the gas to be cooled measured by the temperature sensor reaches the predetermined temperature, the gas flow control element moves to the closed position so as to prevent the passage of the gas to be cooled through the bypass line.

[0129] In one aspect according to the invention, at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably 100% of the flow of gas to be cooled passes into the bypass line when the temperature of the gas to be cooled measured by the temperature sensor in the circuit of gas to be cooled is greater than the predetermined temperature.

[0130] In one aspect according to the invention, the predetermined temperature is between 20 Kelvin and 80 Kelvin, preferably between 20 Kelvin and 40 Kelvin.

[0131] In one aspect according to the invention, the process includes a step of controlling the flow rate of treated gas in the reinjection line, said control being carried out by a flow control device for the treated gas, in other words, the diverted gas, possibly heated, compressed and possibly expanded.

[0132] In one aspect of the invention, the step of reinjecting the treated gas into the gas circuit to be cooled is carried out during the start-up phase of the installation.

[0133] Thus, once the installation is running, i.e. the gas to be cooled has reached the predetermined temperature measured in the circuit of gas to be cooled downstream of the second cold box, the reinjection line no longer reinjects gas into the circuit of gas to be cooled.

[0134] In one aspect according to the invention, during the step of controlling the flow of the treated gas, when the flow control device of the treated gas is in the open position, the treated gas passes into the reinjection line and when the flow control device of the treated gas is in the closed position the treated gas does not pass into the reinjection line.

[0135] In one aspect according to the invention, depending on the temperature of the gas to be cooled measured by the temperature sensor, the treated gas flow control element controls the reinjection of the treated gas into the circuit of gas to be cooled. Thus, when the measured temperature is less than or equal to a predetermined temperature, the treated gas flow control element is in the open position, and when the measured temperature is greater than the predetermined temperature, the treated gas flow control element is in the closed position.

[0136] In one aspect according to the invention, the cycle gas of the cooling circuit comprises hydrogen.

[0137] In one aspect according to the invention, the method includes a step of compressing at least the cycle gas in the cooling circuit, the cycle gas being compressed by a cycle gas compression element in the cooling circuit arranged to compress at least said cycle gas.

[0138] In one aspect according to the invention, the compression step is carried out in two sub-steps: - A low-pressure compression of the cycle gas by a low-pressure compression device, during said low-pressure compression at least the cycle gas is compressed from a pressure of 1 bara to a pressure between 5 and 10 bara followed by, - A high-pressure compression of the cycle gas by a high-pressure compression device, during said high-pressure compression at least the cycle gas is compressed from a pressure of 5 to 10 bara to a pressure between 40 and 80 bara.

[0139] In one aspect according to the invention, the process includes a step of heating at least the cycle gas by a cycle gas heating element arranged in the cooling circuit, said heating element being arranged to heat at least the cycle gas.

[0140] In one aspect according to the invention, the process includes a step of expanding the cycle gas following its compression by an expansion member arranged to expand at least the cycle gas, said expansion member being arranged in the cooling circuit.

[0141] In one aspect of the invention, the cooling circuit includes at least one expansion member arranged to expand the gas to an intermediate pressure of in particular between 5 and 10 bara, and at least one expansion member arranged to expand the gas to a low pressure of in particular between 1 and 2 bara.

[0142] In one aspect according to the invention, the expansion member arranged to expand the gas to an intermediate pressure is disposed on a bypass line of at least one expansion member arranged to expand the cycle gas to low pressure. In other words, when the cycle gas flows in the bypass line, the cycle gas is expanded by the intermediate pressure expansion member, and when the cycle gas does not flow in the bypass line, the cycle gas is expanded by the low pressure expansion member.

[0143] In one aspect of the invention, the medium pressure expansion device comprises at least one turbine.

[0144] In one aspect of the invention, the low pressure expansion member comprises at least one Joule-Thomson effect valve.

[0145] In one aspect according to the invention, the bypass line is arranged to return the expanded cycle gas to at least one medium pressure expansion member upstream of a high pressure compression member, preferably between a low pressure compression member and a high pressure compression member.

[0146] In one aspect according to the invention, the cooling circuit is arranged to circulate a portion of the cycle gas in the bypass line so that said portion of the gas passes through at least one medium pressure expansion member and another portion of the cycle gas to the low pressure expansion member.

[0147] In one aspect of the invention, the cooling circuit is arranged so that the portion of cycle gas passing through the medium pressure expansion member is then directed upstream of a high pressure compression member, preferably between a low pressure compression member and a high pressure compression member, and the other portion of cycle gas passing through at least one low pressure expansion member is then directed upstream of a low pressure compression member of the cooling circuit.

[0148] In one aspect according to the invention, the process comprises at least two steps of diverting the gas to be cooled into at least two separate bypass lines, the gas to be cooled diverted into the bypass lines being compressed, optionally heated, and optionally expanded before being reinjected into the gas circuit. cooled by at least one reinjection line.

[0149] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by at least one bypass line.

[0150] In one aspect according to the invention, during the step of diverting the gas to be cooled, the gas to be cooled is diverted from the gas circuit to be cooled by the bypass line to at least one gas cycle compression element of the cooling circuit arranged on the cooling circuit. The at least one gas cycle compression element of the gas circuit to be cooled is then arranged to compress the diverted gas in addition to the cycle gas.

[0151] The second stage of diverting the gas to be cooled allows in particular to cool the second cold box so that it reaches its operating temperature of between 40 kelvin and 20 kelvin during the start-up phase of the installation.

[0152] In one aspect according to the invention, during the cycle gas diversion step, the diverted gas to be cooled is fed to a cycle gas heating element in the cooling circuit, in particular before its compression. The cycle gas heating element is then arranged to heat the diverted gas and the cycle gas.

[0153] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass pipe downstream of the first part of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the first cold box.

[0154] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass line downstream of the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box.

[0155] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass line upstream of the cryogenic purifier in the direction of flow of the gas to be cooled, in particular in the first cold box.

[0156] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass pipe downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box.

[0157] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass line upstream of the cryogenic purifier and upstream of the first part of the heat exchanger assembly. of heat in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the first part of the heat exchanger assembly, particularly in the first cold box.

[0158] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass pipe upstream of the first part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in particular upstream of the first cold box.

[0159] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass pipe upstream of the first part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in particular upstream of the first cold box.

[0160] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass pipe upstream of the first part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in particular upstream of the first cold box.

[0161] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled to the cooling circuit by a bypass line downstream of the second part of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box.

[0162] In one aspect according to the invention, the gas to be cooled is diverted towards the cooling circuit upstream of at least one compression member in the direction of circulation of the cycle gas of the cooling circuit.

[0163] In one aspect according to the invention, the gas to be cooled is diverted from the gas circuit to be cooled downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box, towards at least one gas cycle compression element of the cooling circuit,

[0164] In this way, the gas to be cooled is diverted after its purification in the cryogenic purifier and arrives sufficiently pure in the cycle gas compression unit.

[0165] In one aspect according to the invention, during the step of reinjecting the treated gas into the gas circuit to be cooled by the reinjection line, the treated gas is reinjected into the gas circuit to be cooled upstream of the first part of the heat exchanger assembly and the first cold box in the direction of flow of the gas to be cooled.

[0166] In one aspect according to the invention, the gas to be cooled is diverted to at least one compression element of the cooling circuit, said gas to be cooled being diverted from the gas circuit upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box, in other words before any cooling stage of said gas.

[0167] This embodiment is particularly advantageous when the cryogenic purifier is not yet at a sufficiently cold temperature to enable it to perform its function and the source of gas to be cooled is pure.

[0168] In one aspect according to the invention, during the step of reinjecting the treated gas into the gas circuit to be cooled by the reinjection line, the treated gas is reinjected into the gas circuit to be cooled upstream of the first part of the heat exchanger assembly and in particular of the first cold box in the direction of flow of the gas to be cooled.

[0169] In one aspect according to the invention, the gas to be cooled is diverted to at least one compression element of the cooling circuit, said gas to be cooled being diverted from the gas to be cooled circuit downstream of the cryogenic purifier, in other words after its cryogenic purification, and upstream of the second part of the heat exchanger assembly, in particular in the first cold box.

[0170] In one aspect according to the invention, during the step of reinjecting the treated gas into the circuit of the gas to be cooled by the reinjection line, the treated gas is reinjected into the circuit of the gas to be cooled downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box.

[0171] In one aspect according to the invention, the gas to be cooled is diverted to at least one compression element of the cooling circuit, said gas to be cooled being diverted from the gas to be cooled circuit downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier, in other words after its cryogenic purification, and the second part of the heat exchanger assembly, in particular in the first cold box.

[0172] In one aspect according to the invention, during the step of reinjecting the treated gas into the circuit of the gas to be cooled by the reinjection line, the treated gas is reinjected into the circuit of the gas to be cooled upstream of the cryogenic purifier and downstream of the first part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the first part of the heat exchanger assembly, in particular in the first cold box.

[0173] In one aspect according to the invention, the gas to be cooled is diverted to at least one low-pressure compression element of the cooling circuit, said gas to be cooled being diverted from the gas circuit downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of flow of the gas to be cooled, in other words, between the cryogenic purifier and the second part of the set of heat exchangers, particularly in the first cold box.

[0174] In one aspect according to the invention, during the step of reinjecting the treated gas into the gas circuit to be cooled by the reinjection line, the treated gas is reinjected from the cooling circuit between the low pressure compression element and the high pressure compression element into the gas circuit to be cooled upstream of the first part of the heat exchanger assembly and the first cold box.

[0175] In one aspect according to the invention, the gas to be cooled is diverted to at least one high-pressure compression element of the cycle gas of the cooling circuit, said gas to be cooled being diverted from the gas circuit to be cooled downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box.

[0176] In one aspect according to the invention, the gas to be cooled is diverted to at least one low-pressure compression element of the cycle gas of the cooling circuit, said gas to be cooled being diverted from the gas circuit to be cooled downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box.

[0177] In one aspect according to the invention, the gas to be cooled is diverted between a low-pressure compression element and a high-pressure compression element of the cycle gas of the cooling circuit, said gas to be cooled being diverted from the circuit of gas to be cooled downstream of the second part of the heat exchanger assembly, in particular in the second cold box.

[0178] In one aspect according to the invention, during the step of reinjecting the treated gas into the gas circuit to be cooled by the reinjection line, the treated gas is reinjected from the cooling circuit between the low pressure compression element and the high pressure compression element into the gas circuit to be cooled upstream of the first cold box.

[0179] In one aspect according to the invention, the process for liquefying a gas, in particular hydrogen, using a hydrogen liquefaction plant, said process comprising: - a step of supplying a gas to be cooled in a gas cooling circuit, - a cooling step for said gas circuit to be cooled, implemented by a cooling device comprising a cooling circuit with a refrigeration cycle of a cycle gas, in particular hydrogen, - at least one step of diverting said gas to be cooled through a pipeline diversion of said gas to be cooled to a third compression unit arranged to compress the diverted gas, and possibly to a heating unit arranged to at least reheat said diverted gas, the heating step being able to be carried out before and / or after the compression of said gas, said third compression unit and / or said third heating unit being arranged on a third circuit separate from the cooling circuit, - a step of reinjection of the gas thus treated into the gas circuit to be cooled by a reinjection line of said treated gas. - at least one reinjection line for the gas thus treated, said reinjection line being arranged to reinject the gas thus treated into the gas circuit to be cooled.

[0180] In one aspect according to the invention, the gas to be cooled is diverted by at least one bypass line to a third circuit, the third circuit comprising the third compression element arranged to compress the diverted gas and / or the third heating element arranged to heat the diverted gas.

[0181] In one aspect according to the invention, the cooling device does not include the third circuit. In other words, the third circuit is not part of the cooling circuit.

[0182] In one aspect according to the invention, the gas to be cooled is diverted to a third circuit comprising at least one third heating element and / or one third compression element where it is at least partially treated, i.e. either heated or compressed, and then to at least one heating element and / or one compression element of the cooling circuit.

[0183] In one aspect according to the invention, the gas to be cooled is diverted successively to a third heating element separate from the cycle gas heating element and then to at least one cycle gas compression element of the cooling circuit. Thus, the gas to be cooled is diverted through a bypass line, heated by a third heating element and then compressed by a cycle gas compression element in the cooling circuit.

[0184] In one aspect according to the invention, the gas to be cooled is diverted to a third circuit, in particular to a third compression element and / or a third heating element, said gas to be cooled being diverted from the gas to be cooled circuit downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box.

[0185] In one aspect according to the invention, during the step of reinjecting the treated gas into the gas circuit to be cooled via the reinjection line, the treated gas is reinjected from from the cooling circuit to the gas circuit to be cooled upstream of the first cold box.

[0186] In one aspect according to the invention, the gas to be cooled is diverted to a third circuit, in particular to a third compression element, said gas to be cooled being diverted from the gas to be cooled circuit downstream of the cryogenic purifier and upstream of the second part of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the heat exchanger assembly, in particular in the first cold box.

[0187] In one aspect according to the invention, the compression of the gas diverted by the bypass line is carried out by the third compression element of the third circuit.

[0188] In one aspect according to the invention, the third compression element is a compressor arranged to compress at least one vaporized gas, in particular from a cryogenic storage. This may be, for example, exhaust gas, called Boil-Off Gas (BOG).

[0189] In one aspect according to the invention, the heating step of the diverted gas is carried out by a third heating element arranged in the third circuit downstream of the compression of said gas in the third compression element.

[0190] Alternatively, the heating step by the third heating element is carried out upstream of the compression carried out by the third compression element in the direction of circulation of the gas to be cooled diverted in the third circuit.

[0191] In one aspect according to the invention, during the step of reinjecting the treated gas into the gas circuit to be cooled by the reinjection line, the treated gas is reinjected from the third circuit into the gas circuit to be cooled upstream of the first cold box.

[0192] In the description, reference is made to temperatures in Kelvin and in other cases to temperatures in degrees Celsius.

[0193] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0194] [Fig.l] The [Fig.l] is a schematic representation of an installation for the liquefaction of hydrogen according to a first embodiment;

[0195] [Fig.2] Fig.2 is a schematic representation of an installation for the li hydrogen fractionation according to a second embodiment;

[0196] [Fig.3] Fig.3 is a schematic representation of an installation for the li hydrogen fractionation according to a third embodiment;

[0197] [Fig.4] Fig.4 is a schematic representation of an installation for the li hydrogen fractionation according to a fourth embodiment;

[0198] [Fig.5] Fig.5 is a schematic representation of an installation for the li- hydrogen fractionation according to a fifth embodiment;

[0199] [Fig.6] Fig.6 is a schematic representation of an installation for the li hydrogen fractionation according to a sixth embodiment;

[0200] [Fig.7] Fig.7 is a schematic representation of an installation for the li hydrogen fractionation according to a seventh embodiment;

[0201] [Fig.8] Fig.8 is a schematic representation of an installation for the li hydrogen fractionation according to an eighth embodiment.

[0202] The features, variants, and different embodiments of the invention may be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0203] In this description, certain elements or parameters may be indexed. In this case, it is simply indexing to differentiate and name similar but not identical elements, parameters, or criteria. This indexing does not imply any priority of one element, parameter, or criterion over another, and such names can easily be interchanged without departing from the scope of this description. Nor does this indexing imply any order in time, for example, for evaluating one criterion over another.

[0204] Figures 1 to 8 schematically represent a liquefied hydrogen production installation 1, comprising a gas circuit to be cooled 2, here containing hydrogen. The installation 1 is divided into two successive parts: 1) pre-cooling of the gas circuit to be cooled 2, and 2) cooling of the gas circuit to be cooled 2, ensuring its liquefaction. The pre-cooling is carried out with a pre-cooling device 10 comprising a pre-cooling circuit 11 with a nitrogen cycle or a mixture composed of hydrocarbons with the empirical formula CnHm and nitrogen and / or argon. The cooling is carried out by a cooling device 13 comprising a cooling circuit 14 that uses a hydrogen cycle or a helium cycle. These pre-cooling 10 and cooling 13 devices use a set of heat exchangers 5, 6 to operate the pre-cooling and cooling of the 2.

[0205] The pre-cooling circuit 11 of the pre-cooling device 10 is in heat exchange with a first part 5 of the heat exchanger assembly so as to pre-cool the gas circuit to be cooled 2 to a first determined temperature, in particular a temperature close to 80 Kelvin. The cooling device-

[0206]

[0207]

[0208]

[0209]

[0210] division 13 including the cooling circuit 14 is in heat exchange with the first part 5 of the heat exchanger assembly and a second part 6 of the heat exchanger assembly(ies) in such a way as to cool the gas circuit to be cooled 2 to a second determined temperature lower than the first temperature, in particular a temperature close to 20 Kelvin. Installation 1 includes a first cold box 3 in which is arranged: - the first part 5 of the heat exchanger assembly for cooling the gas circuit to be cooled 2 to the first determined temperature, - a cryogenic purifier 9, in particular of type TSA, which includes two adsorption cylinders 12, the cryogenic purifier 9 being arranged on the gas circuit to be cooled 2, and optionally a regeneration circuit configured to regenerate the cryogenic purifier 9, and arranged at least partially in the first cold box 3 on the gas circuit to be cooled 2, - optionally a catalytic device arranged on the gas circuit to be cooled 2, not shown here, - a second cold box 4, separate from the first cold box 3, and in which is arranged the second part 6 of the heat exchanger assembly for cooling the gas circuit to be cooled 2 to the second determined temperature lower than the first temperature.. Installation 1 includes a hydrogen circuit to be cooled 2 with an upstream end intended to be connected to a gas source 7 and a downstream end intended to be connected to a cryogenic storage unit 8. The heat exchanger assembly 5, 6 is in heat exchange with the hydrogen circuit to be cooled 2. Thus, the pre-cooling device 10, which is in heat exchange with the first part 5 of the heat exchanger assembly 5, is configured to pre-cool the hydrogen circuit to be cooled 2 to 80 Kelvin in the first cold box 3. This pre-cooling device 10 includes, in particular, at least one compressor 21. The cooling device 13 is in heat exchange with the heat exchangers 5, 6 and is configured to cool the hydrogen circuit to be cooled 2 to 20 Kelvin in the second cold box 4. The cooling circuit 14 includes at least one compression element arranged to compress at least the cycle hydrogen of the cooling circuit 14 and a heating element 20 forming part of the first part of the heat assembly arranged to heat at least the cycle hydrogen of the cooling circuit 14. The cooling circuit 14 includes at least one expansion device 16 for the compressed cycle gas arranged to expand at least said compressed cycle gas. Across all figures 1 to 8, installation 1 includes at least one pipe of A bypass is arranged to divert hydrogen from the gas circuit to be cooled 2 to a compression and / or heating element. The diverted hydrogen is thus recycled, compressed, and possibly heated so that it can be used in installation 1 without being lost to the atmosphere.

[0211] The installation 1 represented in all embodiments further includes at least one reinjection line arranged to reinject the treated gas (i.e. compressed by the compression member 15 or 56 and possibly heated by the heating member) into the gas circuit to be cooled 2 during the start-up phase of the installation 1.

[0212] The start-up phase of such an installation 1 corresponds to the period between the start-up of the installation 1 and the moment when the temperature of the gas to be cooled, measured in the gas circuit to be cooled 2 in the second cold box 4 downstream of the second set of heat exchangers in the direction of gas flow, reaches a predetermined temperature between 20 Kelvin and 80 Kelvin, preferably between 20 Kelvin and 40 Kelvin. Until this start-up phase is complete, i.e., until the predetermined temperature is reached, hydrogen to be cooled is generally lost to the atmosphere. The purpose of the present invention and the various embodiments described herein is to limit these losses.

[0213] Thus, the installation 1 shown in Figures 1 to 8 is arranged so that at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably 100% of the flow of gas to be cooled is diverted to the bypass line during a start-up phase of said installation 1.

[0214] The installation includes a temperature measuring sensor 100, preferably of the resistive type, configured to measure the temperature of the gas to be cooled in the gas circuit 2 in the second cold box 4 downstream of the second set 6 of heat exchangers in the direction of flow of the gas to be cooled. The bypass lines are arranged to divert the gas to be cooled to at least one compression element 15, 56 according to the temperature of the gas to be cooled measured by the temperature sensor 100.

[0215] The bypass line includes a gas flow control device configured to control the flow rate of the gas to be cooled in the bypass line according to the temperature of the gas to be cooled measured by the temperature sensor 100. Thus, when the temperature of the gas to be cooled is higher than the predetermined temperature, the gas flow control device is in the open position so as to allow the gas to be cooled to pass into the bypass line, and when the temperature of the gas to be cooled measured by the temperature sensor When the predetermined temperature is reached, the gas flow control device for the cooled gas moves to the closed position to prevent the passage of the gas to be cooled into the bypass line. The gas flow control device for the cooled gas is arranged to allow 50% to 100%, preferably 60% to 100%, preferably 70% to 100%, preferably 80% to 100% of the gas to be cooled to pass into the bypass line when the temperature of the gas to be cooled, as measured by the temperature sensor in the gas circuit, is higher than the predetermined temperature.

[0216] The reinjection line includes a treated gas flow control device arranged to control the passage of treated gas in the reinjection line as a function of the temperature of the gas to be cooled measured by the temperature sensor 100.

[0217] Thus, during the start-up phase, the temperature of the gas circuit to be cooled is measured, and depending on this temperature, the hydrogen to be cooled is diverted and then reinjected when the system is started. Once the system is started, that is, when the predetermined temperature is reached, the hydrogen to be cooled is no longer diverted except when necessary (for example, a leak in the hydrogen cycle of the cooling circuit).

[0218] We will now describe in more detail the different embodiments shown in Figures 1 to 8.

[0219] The installation 1 shown in Figures 1 to 6 includes at least one bypass line arranged to divert the hydrogen circulating in the gas circuit to be cooled 2 to the cooling circuit 14. Thus, in this case, the hydrogen from the gas circuit to be cooled 2 mixes with the hydrogen from the cooling circuit 14 of the installation 1. The hydrogen from the cooling circuit 14 can therefore be used in the cooling cycle during the start-up of the installation 1.

[0220] In [Fig.1], the installation 1 includes two bypass lines 17, 18. One of the bypass lines 18, referred to herein as the first bypass line, includes one end connected to the gas circuit to be cooled 2 downstream of the first part 5 of the heat exchanger assembly and the cryogenic purifier 9 in the direction of flow of the gas to be cooled, in particular in the first cold box, and another end connected to the cooling circuit 14 upstream of at least one compression element 15 in the direction of flow of the cycle gas of the cooling circuit 14. In this way, the gas to be cooled is diverted after its purification in the cryogenic purifier 9 and arrives sufficiently pure in the compression element 15 of the cycle gas.

[0221] The other bypass line (also called the second bypass line) 17 is connected at one end to the gas circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box 4, and by its other end to the cooling circuit 14, in particular in the second cold box 4, in particular downstream of the expansion member 16 of the cooling circuit 14.

[0222] The installation 1 further includes a reinjection line 19 for the treated gas, said reinjection line 19 having two ends, one of its ends being connected to the cooling circuit 14 downstream of the compression unit 15 in the direction of circulation of the cycle gas of the cooling circuit 14, the other end being connected to the circuit of gas to be cooled 2 upstream of the first part 5 of the heat exchanger assembly, in particular upstream of the first cold box 3 in the direction of circulation of the gas to be cooled.

[0223] Thus, in this embodiment, particularly during the start-up phase of the installation 1, the hydrogen to be cooled is diverted from the gas circuit to be cooled 2 after being purified and / or after circulating in the second part of the heat exchanger assembly to join the cooling circuit 14 and be mixed with the cycle hydrogen, then it is reinjected into the gas circuit to be cooled upstream of the first cold box 3.

[0224] In the embodiment of [Fig. 2], the installation 1 comprises two bypass lines 17, 18. One of the bypass lines 18 (also called the first bypass line) has one end connected to the gas circuit to be cooled 2 upstream of the first part of the heat exchanger assembly, in particular in the first cold box 3 in the direction of flow of the gas to be cooled; the other end of the first bypass line 18 is connected to the cooling circuit 14 upstream of at least one compression element 15 in the direction of flow of the cycle gas. This embodiment is particularly advantageous when the cryogenic purifier 9 is not yet at a sufficiently cold temperature to allow it to perform its function and / or when the source of gas to be cooled is pure.

[0225] The other bypass pipe, also called the second bypass pipe 18, is connected by one of its ends to the gas circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box 4, and by its other end to the cooling circuit 14, in particular in the second cold box 4, in particular downstream of the expansion device 16 of the cooling circuit 14.

[0226] Installation 1 includes a treated gas reinjection line 19, said reinjection line having two ends, one end being connected to the cooling circuit 14 downstream of the compression unit 15 in the direction of fluid gas flow, the other end being connected to the gas circuit to be cooled 2 upstream of the first part 5 of the heat exchanger assembly. heat, especially upstream of the first cold box 3 in the direction of flow of the gas to be cooled.

[0227] Thus, in this embodiment, particularly during the start-up phase of the installation 1, the hydrogen to be cooled is diverted from the gas circuit to be cooled 2 upstream of the first cold box 3 and / or after circulating in the second part of the heat exchanger assembly to join the cooling circuit 14 and be mixed with the cycle hydrogen, then it is reinjected into the gas circuit to be cooled 2 upstream of the first cold box 3.

[0228] In the embodiment shown in [Fig.3], the installation 1 includes two bypass lines 17, 18. One of the bypass lines 18 (also called the first bypass line) has one end connected to the gas circuit to be cooled 2 downstream of the first part 5 of the heat exchanger assembly and the cryogenic purifier 9 in the direction of flow of the gas to be cooled, in particular in the first cold box 3, the other end of the first bypass line 18 is connected to the cooling circuit 14 upstream of at least one compression element 15 in the direction of flow of the cycle gas.

[0229] The other bypass pipe (also called the second bypass pipe 17) is connected by one of its ends to the gas circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box 4, and by its other end to the cooling circuit 14, in particular in the second cold box 4, in particular downstream of the expansion member 16 of the cooling circuit 14.

[0230] In this embodiment, the installation 1 includes a reinjection line 19 of the treated gas, said reinjection line having two ends, one of its ends being connected to the cooling circuit 14 downstream of the compression member 15 in the first cold box 3 in the direction of circulation of the cycle gas, the other end is connected to the circuit of gas to be cooled 2 downstream of the first part 5 of the assembly of heat exchangers and the cryogenic purifier 9 in the direction of circulation of the gas to be cooled, in particular in the first cold box 3.

[0231] Thus, in this embodiment, particularly during the start-up phase of the installation 1, the hydrogen to be cooled is diverted from the gas circuit to be cooled 2 after being purified by the cryogenic purifier 9 and / or after circulating through the second part of the heat exchanger assembly to join the cooling circuit 14 and be mixed with the cycle hydrogen, then it is reinjected into the gas circuit to be cooled 2 downstream of the cryogenic purifier 9.

[0232] In the embodiment shown in [Fig. 4], the installation 1 comprises two bypass pipes 17, 18. One of the bypass pipes (also called the first bypass pipe 18) has one end connected to the gas circuit at cool 2 downstream of the first part of the assembly of exchangers and the cryogenic purifier 9 in the direction of flow of the gas to be cooled, in particular in the first cold box 3, the other end of the first bypass pipe 18 is connected to the cooling circuit 14 upstream of at least one compression element 15 in the direction of flow of the cycle gas.

[0233] The other bypass pipe 17 (also called the second bypass pipe 26) is connected by one of its ends to the gas circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box 4, and by its other end to the cooling circuit 14, in particular in the second cold box 4, in particular downstream of the expansion member 16 of the cooling circuit 14.

[0234] The installation 1 in this embodiment includes a reinjection line 19 for the treated gas, said reinjection line having two ends, one of its ends being connected to the cooling circuit 14 downstream of the compression member 15 in the direction of circulation of the cycle gas, the other end being connected to the circuit of gas to be cooled 2 between the first part of the heat exchanger assembly and the cryogenic purifier 9, in particular in the first cold box 3.

[0235] Thus, in this embodiment, particularly during the start-up phase of the installation 1, the hydrogen to be cooled is diverted from the gas circuit to be cooled 2 after being purified by the cryogenic purifier 9 and / or after circulating through the second part of the heat exchanger assembly to join the cooling circuit 14 and be mixed with the cycle hydrogen, then it is reinjected into the gas circuit to be cooled 2 upstream of the cryogenic purifier 9.

[0236] In the embodiments shown in Figures 5 and 6, the cooling circuit 14 comprises two cycle gas compression elements, a low-pressure compressor 15a and a high-pressure compressor 15b. A low-pressure compressor is understood here to be a compressor arranged to compress a gas from a pressure of approximately 1 bara to a pressure between 5 and 10 bara. A high-pressure compressor is understood here to be a compressor arranged to compress a gas from a pressure between 5 and 10 bara to a pressure between 40 and 80 bara. The low-pressure compression element 15a and the high-pressure compression element 15b are mounted in series on the cooling circuit 14.The cooling circuit 14 includes a pressure-reducing device 33 arranged to reduce the gas to an intermediate pressure, in particular between 5 and 10 bara, and a pressure-reducing device 16 arranged to reduce the gas to a low pressure, in particular between 1 and 2 bara. The pressure-reducing device arranged to reduce the gas to an intermediate pressure is located on a bypass line 32 of at least one of the pressure-reducing devices. to expand the cycle gas to low pressure, said bypass line 32 being arranged in the cooling circuit 14. In other words, when the cycle gas flows in the bypass line 32, the cycle gas is expanded by the medium pressure expansion member 33, and when the cycle gas does not flow in the bypass line 32, the cycle gas is expanded by the low pressure expansion member. The medium-pressure expansion device 33 includes, for example, at least one turbine, and the low-pressure expansion device 16 includes, for example, at least one Joule-Thomson valve. The bypass line 32 is arranged to return the expanded cycle gas to the medium-pressure expansion device 33 between the low-pressure compression device 15a and the high-pressure compression device 15b of the cooling circuit 14. Thus, the cooling circuit 14 is arranged to circulate a portion of the cycle gas through the bypass line 32 so that this portion of the gas passes through at least one medium-pressure expansion device 33, and another portion of the cycle gas to the low-pressure expansion device.The portion of cycle gas passing through the medium pressure expansion member 33 is then directed upstream of a high pressure compression member 15b, between a low pressure compression member 15a and a high pressure compression member 15b, and the other portion of cycle gas passing through at least one low pressure expansion member 16 is then directed upstream of a low pressure compression member 15a of the cooling circuit 14.

[0237] In the embodiment shown in [Fig. 5], the installation 1 comprises two bypass lines 17, 18 for the hydrogen to be cooled. One of the bypass lines (also called the first bypass line 18) has one end connected to the circuit of gas to be cooled 2 downstream of the first part 5 of the assembly of heat exchangers and the cryogenic purifier 9 in the direction of flow of the gas to be cooled, in particular in the first cold box 3, the other end of the first bypass line 18 is connected to the cooling circuit 14 upstream of a low-pressure compression element 15a in the first cold box 3 in the direction of flow of the cycle gas.

[0238] The other bypass pipe (also called the second bypass pipe 17) is connected by one of its ends to the gas circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box 4, and by its other end to the cooling circuit 14, in particular in the second cold box 4, in particular downstream of the expansion member 16 of the cooling circuit 14.

[0239] In this embodiment, the installation 1 comprises a reinjection line 19 for the treated gas, said reinjection line comprising two ends, one of its ends being connected to the cooling circuit 14 between the control unit The low-pressure compressor 15a and the high-pressure compressor 15b are connected in the direction of the cycle gas flow, with the other end connected to the gas circuit to be cooled 2 upstream of the first part of the heat exchanger assembly, specifically upstream of the first cold box 3, in the direction of the gas flow to be cooled. This is particularly advantageous when the compressors are not oil-free, as it is an energy-efficient embodiment.

[0240] Thus, in this embodiment, particularly during the start-up phase of the installation 1, the hydrogen to be cooled is diverted from the gas circuit to be cooled 2 after being purified by the cryogenic purifier 9 and / or after circulating through the second part of the heat exchanger assembly to join the cooling circuit 14 upstream of the compression elements and be mixed with the cycle hydrogen, then it is reinjected into the gas circuit to be cooled 2 upstream of the first cold box 3.

[0241] In the embodiment shown in [Fig.6], the installation 1 includes four bypass lines 17, 18, 22, 23 of the hydrogen from the hydrogen circuit to be cooled 2. These lines will be referred to here as first line, second line, third line and fourth bypass line.

[0242] The first bypass pipe 18 is connected by one of its ends to the gas circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly in the direction of circulation of the gas to be cooled, in particular in the second cold box 4, and by its other end to the cooling circuit 14, in particular in the second cold box 4, in particular downstream of the expansion member 16 of the cooling circuit 14.

[0243] The second bypass line 17a has one end connected to the gas circuit to be cooled 2, one end of which is connected to the gas circuit to be cooled 2 between the cryogenic purifier 9 and the second part 6 of the heat exchanger assembly, in particular in the first cold box 3, the other end of the bypass line is connected to the cooling circuit 14 between the low pressure expansion member 16 and the low pressure compression member 15a of the cycle gas.

[0244] The third bypass line 22 is connected at one end to the gas circuit to be cooled 2, one end of which is connected to the gas circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly in the direction of flow of the gas to be cooled, in particular in the second cold box 4. The other end of the third bypass line 22 is connected to the cooling circuit 14 downstream of a medium-pressure expansion device 33 and upstream of at least one high-pressure compression device of the cooling circuit 14, in particular in the second cold box 4, in the direction of flow of the cycle gas. In other words, the fourth bypass line is connected to the circuit of cooling 14 on the bypass 32 of the cooling circuit 14 between the medium pressure expansion member 33 and the high pressure compression member 15b in the second cold box.

[0245] The fourth bypass line 23 has one end connected to the gas circuit to be cooled 2 between the cryogenic purifier 9 and the second part of the heat exchanger assembly, specifically in the first cold box 3. The other end of the bypass line is connected to the cooling circuit 14 in the first cold box 3 between a medium-pressure expansion device 33 and a high-pressure compression device for the cryogenic cycle gas. In other words, the first bypass line 23 is connected to the cooling circuit 14 on the bypass line 32 of the cooling circuit 14 downstream of the medium-pressure expansion device 33.

[0246] Installation 1 also includes a treated gas reinjection line 19, said reinjection line 19 having two ends, one of its ends being connected to the cooling circuit 14 downstream of the high-pressure compression unit in the direction of cycle gas flow, the other end being connected to the gas circuit to be cooled 2 upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box 3.

[0247] The compression elements 15a, 15b can be, for example, positive displacement compressors (screw and / or piston) that are dry or oil-lubricated. If the compressors are lubricated, an oil removal system removes the oil mixed with the gas passing through the compression element to prevent the oil from freezing in the heat exchangers or being reinjected into the gas circuit to be cooled 2 via at least one reinjection line. The oil removal system associated with the high-pressure compression element removes sufficient oil to avoid these oil contamination problems. Thus, in this embodiment, the oil potentially used in the compressors is sufficiently removed to allow the treated gas to be reinjected into the gas circuit to be cooled 2 upstream of the cryogenic purifier 9.

[0248] Thus, in this embodiment, particularly during the start-up phase of the installation 1, the hydrogen to be cooled is diverted from the gas circuit to be cooled 2 after being purified by the cryogenic purifier 9 and / or after circulating through the second part of the heat exchanger assembly to join the cooling circuit 14 and be mixed with the cycle hydrogen, then it is reinjected into the gas circuit to be cooled 2 upstream of the first cold box 3.

[0249] In the embodiments shown in Figures 7 and 8, the bypass line is arranged to divert the hydrogen to be cooled to a third circuit 40 comprising a third compression element 56 and / or a third heating element 57. The tier 40 circuit is separate from the cooling circuit 14. In other words, the tier 56 compression unit is separate from the cycle gas compression unit 15, and the tier 57 heating unit is separate from the cycle gas heating unit. To put it another way, the cooling device 13 does not include the tier 50 circuit; that is, the tier 40 circuit is not part of the cooling circuit 14.

[0250] In the embodiment shown in [Fig.7], the installation 1 includes two bypass lines 41, 42. One of the bypass lines, referred to here as the first bypass line 41, is arranged to divert the gas to be cooled successively to a third circuit 40, in particular to a third heating element 57 separate from the heating element 20 of the cycle gas and then to at least one compression element 15 of the cycle gas of the cooling circuit 14.Said first bypass line 41a one end is connected to the gas circuit to be cooled 2 downstream of the first part 5 of the heat exchanger assembly and the cryogenic purifier 9 in the direction of flow of the gas to be cooled, in particular upstream of the second heat exchanger assembly, in particular in the first cold box and the other end is connected to the third circuit 40, said third circuit being connected to the cooling circuit 14 upstream of at least one cycle gas compression element of the cooling circuit 14 in the direction of flow of the cycle gas, the bypass line 41 being arranged to divert the gas to be cooled successively towards the third heating element 57 and then towards the cycle gas compression element of the cooling circuit 14.

[0251] Installation 1 includes another bypass line, referred to herein as second bypass line 42. The second bypass line is connected by one of its ends to the third circuit 40 upstream of the third heating element 57 in the direction of flow of the diverted gas in the third circuit 40, and possibly upstream of the third heating element 57, and the other end is connected to the gas circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly.

[0252] The installation 1 further includes a reinjection line 39 of the treated gas, said reinjection line having two ends, one of its ends being connected to the cooling circuit 14 downstream of at least one compression element 15 of the cycle gas of the cooling circuit 14 in the direction of circulation of the cycle gas, the other end being connected to the circuit of gas to be cooled 2 upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box 3 in the direction of circulation of the gas to be cooled.

[0253] In the embodiment shown in [Fig. 8], the installation 1 comprises two bypass lines 52, 53. One of the bypass lines 53, here referred to as the first bypass line, has one end connected to the circuit for the gas to be cooled. 2 downstream of the first part 5 of the assembly of exchangers and the cryogenic purifier 9 in the direction of flow of the gas to be cooled, in particular in the first cold box 3, and its other end is connected upstream of a third compression element 56 separate from at least one compression element 15 of the cycle gas of the cooling circuit 14, the third compression element 56 being in particular arranged on a third circuit 50 separate from the cooling circuit 14. The diverted compressed gas is then heated by a third heating element 57 arranged on the third circuit 50.

[0254] The installation 1 includes a second bypass line 52 comprising two ends, one of its ends being connected to the hydrogen circuit to be cooled 2 downstream of the second part 6 of the heat exchanger assembly, in particular in the second cold box 4, and the other end is connected to the third circuit 50 upstream of the third compression member 56 in the direction of flow of the diverted gas in the third circuit 50.

[0255] The installation 1 includes at least one reinjection line 54, said reinjection line 54 being connected by one of its ends to the third circuit 50 downstream of the third compression element 56 in the direction of flow of the diverted gas in the third circuit 50, and possibly downstream of the third heating element 57, and the other end is connected to the gas circuit to be cooled 2 upstream of the first part of the heat exchanger assembly, in particular upstream of the first cold box 3 in the direction of flow of the gas to be cooled.

Claims

Demands

1. Installation (1) for the production of a cryogenic fluid, in particular liquefied hydrogen, comprising: - a circuit for the gas to be cooled (2) having an upstream end intended to be connected to a gas source (7) and a downstream end intended to be connected to at least one receiving system (8), for example a cryogenic storage, - a set of heat exchangers (5, 6) in heat exchange with the gas circuit to be cooled (2), - a cooling device (13) arranged to cool the gas circuit to be cooled (2) by heat exchange with at least one heat exchanger, the cooling device (13) comprising a cooling circuit (14) with a refrigeration cycle of a cycle gas, the cycle gas comprising in particular hydrogen or helium, - at least one bypass line (17, 18, 22, 23, 42, 41, 52, 53) of the gas to be cooled, said bypass line (17, 18, 22, 23, 42, 41, 52, 53) being arranged to divert the gas to be cooled from the gas circuit to be cooled (2) to at least one compression unit (15) arranged to compress at least the diverted gas to be cooled and possibly to a heating unit (20) arranged to heat at least the diverted gas, said bypass line being arranged in particular upstream of the receiving system in the direction of flow of the gas to be cooled, - at least one reinjection line (19, 39, 54) of the gas thus treated, said reinjection line being arranged to reinject the gas thus treated into the circuit of gas to be cooled (2), the installation (1) being arranged so that at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably 100% of the flow of gas to be cooled is diverted to the bypass line (17, 18, 22, 23, 42, 41, 52, 53) during a start-up phase of said installation (1).

2. Installation (1) according to claim 1, characterized in that it understand : - a pre-cooling device comprising a pre-cooling circuit in heat exchange with at least a first part of the heat exchanger assembly and configured to pre-cool the gas circuit to be cooled (2) to a first determined temperature, in particular a temperature close to 80 Kelvin, - the cooling device comprising the cooling circuit (14) in heat exchange with at least a second part of the heat exchanger assembly(ies) and configured to cool the gas circuit to be cooled (2) to a second determined temperature lower than the first temperature, in particular a temperature close to 20 Kelvin, - at least one first cold box (3) in which is placed: • the first part of the heat exchanger assembly for cooling the gas circuit to be cooled (2) to the first determined temperature, • a cryogenic purifier (9), arranged on the gas circuit to be cooled (2), and optionally a regeneration circuit configured to regenerate the cryogenic purifier (9), and disposed at least partially in the first box on the gas circuit to be cooled (2), - at least one second cold box (4), separate from the first cold box (3), and in which is arranged the second part of the heat exchanger assembly(ies) for cooling the gas circuit to be cooled (2) to the second determined temperature lower than the first temperature, - a temperature measuring sensor, preferably of the resistive type, configured to measure the temperature of the gas to be cooled in the gas circuit to be cooled (2) in the second cold box (4) downstream of the second set of heat exchangers in the direction of flow of the gas to be cooled.

3. Installation (1) according to the preceding claim, characterized in that the bypass pipe (17, 18, 22, 23, 42, 41, 52, 53) is arranged to divert the gas to be cooled towards at least one compression element depending on the temperature of the gas to be cooled measured by the temperature sensor.

4. Installation (1) according to any one of the preceding claims, characterized in that it comprises at least two bypass lines (17, 18, 22, 23, 42, 41, 52, 53), the two bypass lines being arranged to divert the gas to be cooled to a compression element of said gas and optionally to a heating element of said gas, the two bypass lines being arranged to divert the gas to different locations in the installation (1).

5. Installation (1) according to any one of the preceding claims, characterized in that the bypass line (17, 18, 22, 23) comprises two ends, one of its ends being connected to the gas circuit to be cooled (2) and the other end being connected to the cooling circuit (14), in particular upstream of a cycle gas compression device.

6. Installation (1) according to any one of the preceding claims, characterized in that the bypass line (17, 18, 22, 23) is arranged to divert the gas to be cooled towards the heating element of the cycle gas of the cooling circuit (14), in particular upstream of at least one heating element of the cooling circuit (14).

7. Installation (1) according to any one of the preceding claims, characterized in that the reinjection line (19, 38) is connected by one of its ends to the gas circuit to be cooled (2) and by its other end to the cooling circuit (14) downstream of a cycle gas compression device.

8. A process for liquefying a gas, in particular hydrogen, using a hydrogen liquefaction plant (1), said process comprising, during a start-up phase of said plant (1): - a step of supplying a gas to be cooled into a gas-to-cool circuit (2), - a step of cooling said gas-to-cool circuit (2) implemented by a cooling device comprising a cooling circuit (14) with a cycle refrigeration system for a cycle gas, in particular hydrogen, - at least one step of diverting said gas to be cooled by a bypass line to a component compression arranged to compress the diverted gas, and possibly to a heating element arranged to heat at least said diverted gas, the heating step being able to be carried out before and / or after the compression of said gas, - a step of reinjection of the gas thus treated into the circuit of gas to be cooled (2) by a reinjection line of said treated gas.

9. A method according to the preceding claim, characterized in that during the step of diverting the gas to be cooled, at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably 100% of the flow of gas to be cooled is diverted to the bypass line during a start-up phase of the installation (1).

10. A method according to any one of the preceding claims, characterized in that during the step of diverting the gas to be cooled, the gas to be cooled is diverted from the gas circuit to be cooled (2) by the bypass line to at least one gas cycle compression element of the cooling circuit (14) arranged on the cooling circuit (14).

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