Cryogenic fluid production facility

Abstract

Installation for producing 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 pipe 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 member arranged to compress the diverted gas to be cooled, a pipe for re-injecting the gas thus treated, said re-injection pipe being arranged to re-inject 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 pipe during a start-up phase of said installation. Figure for the abstract: Fig. 1

Description

Title of the invention: Installation for producing a cryogenic fluid

[0001] The field of the present invention is that of a plant for producing 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 vector 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, with in particular one or more pre-cooling cycles and a cooling cycle. The refrigeration fluid circulating in the cooling cycle is either helium, or hydrogen, or a helium / neon mixture. Cryogenic purification is carried out during the liquefaction of the hydrogen.

[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 being burned in a stack creates a flammable cloud. If this ignites (e.g. in the presence of an energy source such as snowfall, thunderstorms, a hot spot, radiation), this can cause safety issues (delayed ignition causing an overpressure wave), noise and radiation. This can create acceptance constraints around the liquefier due to the noise generated and requires consideration of sufficient distances between equipment as well as sending the hydrogen release to a high height and / or burning it in a flare.

[0005] The releases of hydrogen into the atmosphere for a liquefier can be of different natures such as exceptional releases (e.g. overpressure control), regular releases (e.g. regeneration of hydrogen purification) or even releases linked to the start-up of the unit, in particular the release of the 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 pipes, 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] It is now important to reduce the safety risks and costs associated with hydrogen releases, particularly at the start-up of the liquefaction process for liquefiers likely to restart frequently.

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

[0009] The subject of the invention relates to an installation for producing a cryogenic fluid, in particular liquefied hydrogen, comprising: - a gas circuit 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 cryogenic storage, - 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 pipe for the gas to be cooled, said bypass pipe being arranged to divert the gas to be cooled from the gas to be cooled circuit to at least one compression member arranged to compress at least the diverted gas to be cooled and possibly to a heating member arranged to heat at least said diverted gas, said bypass pipe being in particular arranged upstream of the receiving system in the direction of circulation of the gas to be cooled, - at least one reinjection pipe for the gas thus treated, said reinjection pipe 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 member is arranged upstream or downstream of the compression member in the direction of circulation of the diverted gas.

[0011] According to one aspect of the invention, the installation comprises at least one expansion member arranged to expand the gas diverted 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, the 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 members arranged to expand the diverted gas downstream of the compression member and upstream of the treated gas reinjection pipe in the direction of circulation of the diverted gas, the set of expansion members comprising turbines and / or Joule-Thomson type valves.

[0014] The installation according to the invention makes it possible to limit the releases 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 is meant the gas to be cooled diverted, possibly reheated, 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 pipe 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 set of heat exchangers 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(s) 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 gas circuit to be cooled, and possibly a regeneration circuit configured to regenerate the cryogenic purifier, and arranged 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, - at least one second cold box, separate from the first cold box, and in which the second part of the heat exchanger assembly is arranged 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 each other, and / or the installation comprises a plurality of second cold boxes arranged in parallel with 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 circulation of the gas to be cooled in the gas circuit to be cooled.

[0020] By installation start-up phase, it is understood 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 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 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 in 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 start-up phase of the installation are reduced.

[0022] In one aspect according to the invention, the installation comprises a temperature measurement 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 pipe is arranged to divert the gas to be cooled towards the 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 pipes, the two bypass pipes being arranged to divert the gas to be cooled towards a compression member of said gas and possibly towards a heating, the two bypass pipes being arranged to divert the gas to different places 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 set of heat exchangers 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 member arranged to compress at least said diverted gas.

[0027] In one aspect according to the invention, the bypass pipe comprises at least one member for controlling the flow rate of the gas to be cooled, in particular a valve, said member for controlling the flow rate of the gas to be cooled being arranged to control the flow rate of the gas to be cooled circulating in the bypass pipe.

[0028] In one aspect according to the invention, the gas flow control member to be cooled is arranged so as to allow the passage of at least a portion of the gas to be cooled in the bypass pipe in the open position and to prevent the passage of the gas to be cooled in the bypass pipe in the closed position. Thus, in the open position, the gas to be cooled is diverted towards the at least one compression member, and in the closed position the gas to be cooled continues to circulate in the gas circuit to be cooled, for example up to the downstream end of the gas circuit to be cooled.

[0029] In one aspect according to the invention, the bypass pipe comprises at least two gas flow control members to be cooled, said gas flow control members 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 members to be cooled are of different sizes.

[0031] In one aspect according to the invention, one of the two gas flow control members to be cooled is arranged to control the flow of gas to be cooled in the bypass pipe during a start-up phase of the installation, the other control member is arranged to control the flow of gas to be cooled once the installation is started. Thus, one of the gas flow control members to be cooled makes it possible to control the flow of gas to be cooled to be diverted in the bypass pipe during the start-up phase of the installation so as to limit the releases of gas to be cooled into the atmosphere, and the other gas flow control member to be cooled makes it possible to control the flow of 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 cycle gas discharges from the cooling circuit when the installation is running (for example in the event of leaks).

[0032] In one aspect according to the invention, the gas flow control member to be cooled 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 flow of gas 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 gas flow control member to be cooled is a controlled-opening valve, for example a Joule-Thomson type valve with controlled opening. The advantage of such a valve is that it can gradually increase the flow rate circulating in the bypass pipe until the temperature of the fluid to be cooled is low enough for the valve to be closed so that the gas to be cooled no longer circulates in the bypass pipe and is sent to the downstream end of the gas circuit to be cooled and then to the system receiving the cooled gas.

[0034] In one aspect according to the invention, the gas to be cooled flow rate control member is configured to control the flow rate of gas to be cooled in the bypass pipe 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 to be cooled flow rate control member is in the open position so as to allow the gas to be cooled to pass into the bypass pipe, and when the temperature of the gas to be cooled measured by the temperature sensor reaches the predetermined temperature, the gas to be cooled flow rate control member moves into the closed position so as to prevent the gas to be cooled from passing into the bypass pipe.

[0035] In one aspect according to the invention, the gas flow rate control member to be cooled 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 rate to be cooled to pass through the bypass pipe when the temperature of the gas to be cooled measured by the temperature sensor in the gas circuit to be cooled is higher than 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, the at least one reinjection pipe 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, that is to say the gas to be cooled has reached the predetermined temperature measured in the gas circuit to be cooled downstream of the second cold box, the reinjection pipe no longer reinjects gas into the gas circuit to be cooled.

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

[0040] In one aspect according to the invention, the treated gas flow control member is arranged to allow the treated gas to pass into the reinjection pipe in the open position and to prevent the treated gas from passing into the reinjection pipe in the closed position. Thus, in the open position, the treated gas can circulate in the reinjection pipe and return to the gas circuit to be cooled, and in the closed position the treated gas cannot circulate in the reinjection pipe and return to the gas circuit to be cooled.

[0041] In one aspect according to the invention, the treated gas flow rate control member is arranged to control the passage of the treated gas into the reinjection pipe 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 pipe 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 member.

[0043] Alternatively, the reinjection pipe is connected by one of its ends to the gas circuit to be cooled and by its other end to a third circuit downstream of a third compression member.

[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 comprises at least one cycle gas compression member.

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

[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 comprises at least one cycle gas heating member arranged to heat at least the cycle gas before it passes into the compression member.

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

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

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

[0052] In one aspect of the invention, the cooling circuit comprises 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 until it reaches 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 arranged on a bypass line of the 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 circulates in the bypass line, the cycle gas is expanded by the medium pressure expansion member, and when the cycle gas does not circulate 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 member 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 the 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 the at least one medium pressure expansion member and another portion of the cycle gas towards 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 the cycle gas passing through the 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- ends, one of its ends is connected to the gas circuit to be cooled and the other end is connected to the cooling circuit, in particular upstream of a cycle gas compression member.

[0060] In one aspect according to the invention, the bypass pipe is arranged to divert the gas to be cooled towards the at least one cycle gas compression member of the cooling circuit. In this case, the cycle gas 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 pipes, one of the bypass pipes being connected by one of its ends to the gas circuit to be cooled downstream of the second part of the set of heat exchangers 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 cooling circuit, in particular in the second cold box, in particular downstream of the expansion member of the cooling circuit. Said bypass pipe makes it possible 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.

[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 member of the cooling circuit, in particular upstream of the at least one heating member of the cooling circuit. In other words, the bypass member is arranged to divert the gas to be cooled before its compression in the cycle gas compression member.

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

[0064] In one aspect according to the invention, the installation comprises at least one bypass pipe comprising one end connected to the gas circuit to be cooled downstream of the first part of exchangers of the set of heat exchangers 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 comprises at least one bypass pipe comprising one end connected to the gas circuit 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 gas circuit to be cooled upstream 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 dissement.

[0067] 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 downstream of the cryogenic purifier and upstream of the second part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, 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 comprises at least one bypass pipe comprising one end connected to the circuit of gas to be cooled downstream of the first part of the set of heat exchangers 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 set of heat exchangers 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 comprises at least one bypass pipe comprising one end connected to the gas circuit to be cooled upstream of the first part of the set of heat exchangers in the direction of circulation 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 comprises at least one bypass pipe comprising one end connected to the gas circuit to be cooled downstream of the second part of the set of heat exchangers in the direction of circulation 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 pipe comprising one end connected to the circuit of gas to be cooled downstream of the first part of the set of heat exchangers and 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 upstream of at least one compression member in the direction of circulation 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 in the cycle gas compression member.

[0073] In one aspect according to the invention, the installation comprises a pipe for re-injecting the treated gas, said re-injection pipe 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 set of heat exchangers, 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 comprises 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 set of heat exchangers, in particular in the first cold box in the direction of circulation 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 member in the direction of circulation of the cycle gas.

[0075] This embodiment is particularly advantageous when the cryogenic purifier is not yet at a temperature cold enough 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 comprises a pipe for re-injecting the treated gas, said re-injection pipe 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 fluid gas, the other end being connected to the circuit of gas to be cooled upstream of the first part of the set of heat exchangers, in particular upstream of the first cold box in the direction of circulation of the gas to be cooled.

[0077] In one aspect according to the invention, the installation comprises 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 set of heat exchangers and of the cryogenic purifier in the direction of circulation 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 member in the direction of circulation of the cycle gas.

[0078] In one aspect according to the invention, the installation comprises a pipe for re-injecting the treated gas, said re-injection pipe 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 circulation of the cycle gas, the other end is connected to the circuit of gas to be cooled downstream of the first part of the set of heat exchangers and the cryogenic purifier in the direction of circulation of the gas to be cooled, in particular in the first cold box.

[0079] In one aspect according to the invention, the installation comprises at least one pipe of bypass, one end of which is connected to the gas circuit to be cooled downstream of the first part of the set of exchangers and the cryogenic purifier in the direction of circulation 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 member in the direction of circulation of the cycle gas.

[0080] In one aspect according to the invention, the installation comprises a pipe for re-injecting the treated gas, said re-injection pipe 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, the other end being connected to the circuit of gas to be cooled downstream of the first part of the set of heat exchangers 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 set of heat exchangers and the cryogenic purifier, in particular in the first cold box.

[0081] In one aspect according to the invention, the installation comprises 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 set of exchangers and of the cryogenic purifier in the direction of circulation 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 member in the first cold box in the direction of circulation of the cycle gas.

[0082] In one aspect according to the invention, the installation comprises a pipe for re-injecting the treated gas, said re-injection pipe comprising two ends, one of its ends being connected to the cooling circuit between the low-pressure compression member and the high-pressure compression member in the direction of circulation of the cycle gas, the other end being connected to the gas circuit to be cooled upstream of the first part of the set of heat exchangers, in particular upstream of the first cold box in the direction of circulation of the gas to be cooled. This is particularly advantageous when the low-pressure compression member is not oiled or when the low-pressure compression member comprises a de-oiling system downstream thereof making it possible to achieve less than 50 ppb by mass of oil in the hydrogen upstream of the end of the re-injection pipe, in fact it is an energy-saving embodiment.

[0083] In one aspect according to the invention, the installation comprises 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 set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, in particular in the first cold box, the other end of the bypass line being connected to the cooling circuit in the first cold box between a medium pressure expansion member and a high pressure compression member of the cycle gas of 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 member.

[0084] In one aspect according to the invention, the installation comprises at least two bypass pipes, preferably at least three bypass pipes, one of the bypass pipes being connected by one of its ends to the circuit of gas to be cooled, 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 set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, in particular in the first cold box, the other end of the bypass pipe 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 pipes, one of the bypass pipes being connected by one of its ends to the circuit of gas to be cooled, one end of which is connected to the circuit of gas to be cooled downstream of the second part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in particular in the second cold box, the other end of the bypass pipe 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 circulation 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 member and the high pressure compression member in the second cold box.

[0086] In one aspect according to the invention, the installation comprises a pipe for re-injecting the treated gas, said re-injection pipe comprising two ends, one of its ends being connected to the cooling circuit downstream of the high-pressure compression member in the direction of circulation of the cycle gas, the other end being connected to the circuit of gas to be cooled upstream of the first part of the set of heat exchangers, in particular upstream of the first cold box.

[0087] The compression members may be, for example, volumetric compressors (screw and / or piston technology) which are dry or lubricated with oil. In the case where the compressors are lubricated, an oil removal system makes it possible to removing the oil mixed with the gas passing through the compression member to prevent the oil from freezing in the heat exchangers or being reinjected into the gas circuit to be cooled through the at least one reinjection line. The oil removal system associated with the high-pressure compression member allows sufficient oil to be removed 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 producing a cryogenic fluid, in particular liquefied hydrogen, comprises: - a gas circuit 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 cryogenic storage, - 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 pipe for the gas to be cooled, said bypass pipe being arranged to divert the gas to be cooled from the gas to be cooled circuit to a third circuit comprising at least one third compression member arranged to compress the diverted gas and / or a third heating member arranged to heat the diverted gas, the third circuit being separate from the cooling circuit, - at least one reinjection pipe for the gas thus treated, said reinjection pipe 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 distinct from the gas circuit to be cooled.

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

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

[0093] In one aspect according to the invention, the cooling device does not comprise 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 towards a third heating member distinct from the cycle gas heating member then towards at least one cycle gas compression member of the cooling circuit.

[0095] In one aspect according to the invention, the installation comprises 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 set of heat exchangers and the cryogenic purifier in the direction of circulation 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 the at least one third heating member and / or the at least one third compression member in the direction of circulation of the diverted gas.

[0096] In one aspect according to the invention, the installation comprises 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 set of heat exchangers and the cryogenic purifier in the direction of circulation 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 the at least one third heating member and / or the third compression member in the direction of circulation 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 member then towards the cycle gas compression member of the cooling circuit.

[0098] In one aspect according to the invention, the installation comprises a pipe for re-injecting the treated gas, said re-injection pipe comprising two ends, one of its ends being connected to the cooling circuit downstream of the at least one cycle gas compression member of the cooling circuit in the direction of circulation of the cycle gas, the other end being connected to the circuit of gas to be cooled upstream of the first part of the set of heat exchangers, in particular upstream of the first cold box without the direction of circulation of the gas to be cooled.

[0099] In one aspect according to the invention, the installation comprises at least one pipe of bypass, 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 set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, in particular in the first cold box, and its other end is connected upstream of a third compression member separate from the at least one compression member of the cycle gas of the cooling circuit, the third compression member being in particular arranged on a third circuit separate from the cooling circuit.

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

[0101] In one aspect according to the invention, the third circuit comprises at least one third heating member arranged downstream of the third compression member in the direction of circulation of the gas to be cooled diverted into the third circuit.

[0102] Alternatively, the third-party heating member is arranged upstream of the third-party compression member in the direction of circulation of the gas to be cooled diverted into the third-party 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 set of heat exchangers 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 member and / or a third heating member.

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

[0105] The invention also relates to a method for liquefying a gas, in particular hydrogen, using a hydrogen liquefaction installation, said method comprising during a start-up phase of said installation: - a step of supplying a gas to be cooled into a gas circuit to be cooled, - a step of cooling 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 by a pipe of diverting said gas to be cooled to a compression member arranged to compress the diverted gas, and optionally to a heating member 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 re-injecting the gas thus treated into the gas circuit to be cooled via a pipe for re-injecting said treated gas.

[0106] Advantageously, the method 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 method is implemented in an installation as described previously.

[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 set of heat exchangers 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(s) 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 separation unit type (in English Temperature Swing Adsorption TSA), arranged on the gas circuit to be cooled, and possibly a regeneration circuit configured to regenerate the cryogenic purifier, and arranged 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 the second part of the heat exchanger assembly is arranged 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 circulation of the gas to be cooled in the gas circuit to be cooled.

[0111] In one aspect according to the invention, the gas to be cooled circulating in the circuit of gas to be cooled comes from the source of gas to be cooled, then it first passes 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 method is carried out during a start-up phase of the gas liquefaction installation. In other words, the method is integrated into a start-up phase of the liquefaction installation.

[0113] By installation start-up phase, it is understood 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 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 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 pipe 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, here hydrogen, has not reached the predetermined temperature, said gas to be cooled is recycled in 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 start-up phase of the installation are reduced.

[0116] In one aspect according to the invention, the method comprises 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 set of heat exchangers in the direction of circulation of the gas to be cooled.

[0117] In one aspect of the invention, the temperature measuring step is performed by a temperature sensor.

[0118] In one aspect according to the invention, the step of diverting the gas to be cooled towards at least one compression member 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 towards each at least one compression member and possibly towards at least one heating member.

[0120] In one aspect according to the invention, the method comprises at least two steps of diverting the gas to be cooled towards each at least one compression member and possibly towards at least one heating member, the steps of diverting the gas to be cooled being able to be carried out simultaneously or sequentially in different places of the installation used for implementing the method.

[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 be cooled bypass lines.

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

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

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

[0125] In one aspect according to the invention, the step of controlling the flow rate of gas to be cooled is carried out between the step of supplying the gas to be cooled to the circuit of 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 gas to be cooled, at least a portion of the gas to be cooled passes into the bypass pipe when the gas to be cooled flow rate control member is in the open position and the gas to be cooled does not pass into the bypass pipe when the gas to be cooled flow rate control member is in the closed position. Thus, in the open position, the gas to cooling is diverted to the at least one compression member, and in the closed position the gas to be cooled continues to circulate in the gas circuit to be cooled, for example to the downstream end of the gas circuit to be cooled.

[0127] In one aspect of the invention, the method comprises at least two steps of controlling the flow rate of gas to be cooled carried out by different sized gas to be cooled flow rate control members. For example, one of the two gas to be cooled flow rate control members is arranged to control the flow rate of gas to be cooled in the bypass pipe during a start-up phase of the installation, the other control member is arranged to control the flow rate of gas to be cooled once the installation is started. Thus, one of the gas to be cooled flow rate control members makes it possible to control the flow rate of gas to be cooled to be diverted in the bypass pipe during the start-up phase of the installation so as to limit the releases of gas to be cooled into the atmosphere, and the other gas to be cooled flow rate control member makes it possible to control the flow rate of 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 cycle gas discharges from the cooling circuit when the installation is running (for example in the event of leaks).

[0128] In one aspect according to the invention, during the step of controlling the flow rate of gas to be cooled in the bypass pipe, the passage of the flow rate of gas to be cooled in the bypass pipe is controlled 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 to be cooled flow rate control member is in the open position so as to allow the gas to be cooled to pass into the bypass pipe, and when the temperature of the gas to be cooled measured by the temperature sensor reaches the predetermined temperature, the gas to be cooled flow rate control member goes into the closed position so as to prevent the gas to be cooled from passing into the bypass pipe.

[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 rate of gas to be cooled passes through 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 higher 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 method comprises a step of controlling the flow rate of treated gas in the reinjection pipe, said control being carried out by a member for controlling the flow rate of 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, that is to say the gas to be cooled has reached the predetermined temperature measured in the gas circuit to be cooled downstream of the second cold box, the reinjection pipe no longer reinjects gas into the gas circuit to be cooled.

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

[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 rate control member controls the reinjection of the treated gas into the gas circuit to be cooled. Thus, when the measured temperature is less than or equal to a predetermined temperature, the treated gas flow rate control member is in the open position, and when the measured temperature is greater than the predetermined temperature, the treated gas flow rate control member 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 comprises a step of compressing at least the cycle gas in the cooling circuit, the cycle gas being compressed by a cycle gas compression member 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 member, during said low pressure compression at least the cycle gas is compressed from a pressure of 1 bara to a pressure of between 5 and 10 bara followed by, - High pressure compression of the cycle gas by a high pressure compression member, during said high pressure compression at least the cycle gas is compressed from a pressure of 5 to 10 bara to a pressure of between 40 and 80 bara.

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

[0140] In one aspect according to the invention, the method comprises 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 comprises 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 until it reaches 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 arranged on a bypass line of the at least one expansion member arranged to expand the cycle gas to low pressure. In other words, when the cycle gas circulates in the bypass line, the cycle gas is expanded by the medium pressure expansion member, and when the cycle gas does not circulate 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 member 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 the 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 the at least one medium pressure expansion member and another portion of the cycle gas towards 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 the cycle gas passing through the 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 method comprises at least two steps of diverting the gas to be cooled into at least two separate bypass pipes, the gas to be cooled diverted into the bypass pipes being compressed, optionally heated, and optionally expanded before being reinjected into the gas circuit to be cooled. cool 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 pipe to at least one compression member of the cycle gas of the cooling circuit arranged on the cooling circuit. The at least one compression member 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 makes it possible 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 step of diverting the cycle gas, the diverted gas to be cooled is brought to a cycle gas heating member of the cooling circuit, in particular before its compression. The cycle gas heating member 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 set of exchangers of the set of heat exchangers in the direction of circulation 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 pipe downstream of the cryogenic purifier in the direction of circulation 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 pipe upstream of the cryogenic purifier in the direction of circulation 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 pipe upstream of the cryogenic purifier and upstream of the first part of the 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, in particular 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 pipe 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.

[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 circuit of gas to be cooled downstream of the cryogenic purifier and upstream of the second part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, in particular in the first cold box, towards at least one member for compressing the cycle gas 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 member.

[0165] 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 pipe, the treated gas is reinjected into the gas circuit to be cooled upstream of the first part of the set of heat exchangers and the first cold box in the direction of circulation of the gas to be cooled.

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

[0167] This embodiment is particularly advantageous when the cryogenic purifier is not yet at a temperature cold enough to allow 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 via the reinjection pipe, the treated gas is reinjected into the gas circuit to be cooled upstream of the first part of the set of heat exchangers and in particular of the first cold box in the direction of circulation of the gas to be cooled.

[0169] In one aspect according to the invention, the gas to be cooled is diverted towards at least one compression member of the cooling circuit, said gas to be cooled being diverted from the circuit of gas to be cooled downstream of the cryogenic purifier, in other words after its cryogenic purification, and upstream of the second part of the set of heat exchangers, 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 gas circuit to be cooled via the reinjection pipe, the treated gas is reinjected into the gas circuit to be cooled downstream of the cryogenic purifier and upstream of the second part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, in particular in the first cold box.

[0171] In one aspect according to the invention, the gas to be cooled is diverted towards at least one compression member of the cooling circuit, said gas to be cooled being diverted from the circuit of gas to be cooled downstream of the cryogenic purifier and upstream of the second part of the set of heat exchangers 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 set of heat exchangers, 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 gas circuit to be cooled via the reinjection pipe, the treated gas is reinjected into the gas circuit to be cooled upstream of the cryogenic purifier and downstream of the first part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the first part of the set of heat exchangers, in particular in the first cold box.

[0173] In one aspect according to the invention, the gas to be cooled is diverted towards at least one low-pressure compression member of the cooling circuit, said gas to be cooled being diverted from the circuit of gas to be cooled downstream of the cryogenic purifier and upstream of the second part of the set of heat exchangers 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, 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 via the reinjection pipe, the treated gas is reinjected from the cooling circuit between the low-pressure compression member and the high-pressure compression member towards 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 towards at least one high-pressure compression member 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 cryogenic purifier and upstream of the second part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, in particular in the first cold box.

[0176] In one aspect according to the invention, the gas to be cooled is diverted towards at least one low-pressure compression member 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 cryogenic purifier and upstream of the second part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, 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 member and a high-pressure compression member 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 set of heat exchangers, 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 via the reinjection pipe, the treated gas is reinjected from the cooling circuit between the low-pressure compression member and the high-pressure compression member towards the gas circuit to be cooled upstream of the first cold box.

[0179] In one aspect according to the invention, the method for liquefying a gas, in particular hydrogen, using a hydrogen liquefaction installation, said method comprising: - a step of supplying a gas to be cooled into a gas circuit to be cooled, - a step of cooling 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 by a pipe of diverting said gas to be cooled to a third-party compression member arranged to compress the diverted gas, and possibly to a heating member arranged to reheat at least said diverted gas, the heating step being able to be carried out before and / or after the compression of said gas, said third-party compression member and / or said third-party heating member being arranged on a third-party circuit separate from the cooling circuit, - a step of re-injecting the gas thus treated into the gas circuit to be cooled via a pipe for re-injecting said treated gas. - at least one reinjection pipe for the gas thus treated, said reinjection pipe 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 pipe to a third circuit, the third circuit comprising the third compression member arranged to compress the diverted gas and / or the third heating member arranged to heat the diverted gas.

[0181] In one aspect according to the invention, the cooling device does not comprise 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 member and / or one third compression member where it is at least partially treated, i.e. either heated or compressed, then to at least one heating member and / or one compression member of the cooling circuit.

[0183] In one aspect according to the invention, the gas to be cooled is diverted successively to a third heating member separate from the cycle gas heating member and then to at least one cycle gas compression member of the cooling circuit. Thus, the gas to be cooled is diverted by a bypass pipe, heated by a third heating member and then compressed by a cycle gas compression member 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 member and / or a third heating member, said gas to be cooled being diverted from the circuit of gas to be cooled downstream of the cryogenic purifier and upstream of the second part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, 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 pipe, 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 member, said gas to be cooled being diverted from the circuit of gas to be cooled downstream of the cryogenic purifier and upstream of the second part of the set of heat exchangers in the direction of circulation of the gas to be cooled, in other words between the cryogenic purifier and the second part of the set of heat exchangers, in particular in the first cold box.

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

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

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

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

[0191] 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 pipe, 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 characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several exemplary embodiments given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0194] [Fig.l] [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 quefaction of hydrogen according to a second embodiment;

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

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

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

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

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

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

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

[0203] In the present description, certain elements or parameters may be indexed. In this case, it is a simple indexing to differentiate and name elements or parameters or criteria that are close but not identical. This indexing does not imply a priority of one element, parameter or criterion over another and such names can easily be interchanged without departing from the scope of the present description. This indexing also does not imply an order in time, for example, to assess this or that criterion.

[0204] Figures 1 to 8 schematically show an installation 1 for producing liquefied hydrogen, comprising a circuit 2 for gas to be cooled, here hydrogen, the installation 1 being divided into two successive parts: 1) pre-cooling of the circuit 2 for gas to be cooled, and 2) cooling of the circuit 2 for gas to be cooled 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 of crude formula CnHm and nitrogen and / or argon. The cooling is carried out by a cooling device 13 comprising a cooling circuit 14 which 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 set of heat exchangers 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] dimention 13 comprising the cooling circuit 14 is in heat exchange with the first part 5 of the set of heat exchangers and a second part 6 of the set of heat exchanger(s) so 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. The installation 1 comprises a first cold box 3 in which is arranged: - the first part 5 of the set of heat exchangers for cooling the gas circuit to be cooled 2 to the first determined temperature, - a cryogenic purifier 9, in particular of the TSA type, which comprises two adsorption bottles 12, the cryogenic purifier 9 being arranged on the gas circuit to be cooled 2, and possibly 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, - possibly 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 set of heat exchangers for cooling the gas circuit to be cooled 2 to the second determined temperature lower than the first temperature.. The installation 1 comprises 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 8. The set of heat exchangers 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 set of heat exchangers 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 comprises 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 comprises at least one compression member arranged to compress at least the cycle hydrogen of the cooling circuit 14 and a heating member 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 comprises at least one expansion member 16 for the compressed cycle gas arranged to expand at least said compressed cycle gas. In all of figures 1 to 8, the installation 1 comprises at least one pipe of bypass arranged to divert the hydrogen from the gas circuit to be cooled 2 to a compression member and / or a heating member. The hydrogen to be cooled thus diverted is therefore recycled, compressed and possibly heated so that it can be used in the installation 1 without being lost into the atmosphere.

[0211] The installation 1 shown in all the embodiments further comprises at least one reinjection pipe 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 at which 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 circulation of the gas to be cooled is at a predetermined temperature of between 20 Kelvin and 80 Kelvin, preferably between 20 Kelvin and 40 Kelvin. As long as this start-up phase is not completed, that is to say the predetermined temperature is not reached, hydrogen to be cooled is generally lost into the atmosphere. The aim of the present invention and of the various embodiments described here is to limit these losses.

[0213] Thus, the installation 1 shown in the set of 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 pipe during a start-up phase of said installation 1.

[0214] The installation comprises 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 to be cooled 2 in the second cold box 4 downstream of the second set 6 of heat exchangers in the direction of circulation of the gas to be cooled. The bypass pipes are arranged to divert the gas to be cooled towards the at least one compression member 15, 56 as a function of the temperature of the gas to be cooled measured by the temperature sensor 100.

[0215] The bypass pipe comprises a gas flow control member to be cooled which is configured to control the flow of gas to be cooled in the bypass pipe as a function of 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 member to be cooled is in the open position so as to allow the gas to be cooled to pass into the bypass pipe, and when the temperature of the gas to be cooled measured by the temperature sensor reaches the predetermined temperature, the gas flow control member to be cooled moves to the closed position so as to prevent the gas to be cooled from passing into the bypass line. The gas flow control member to be cooled 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 measured by the temperature sensor in the gas circuit to be cooled is higher than the predetermined temperature.

[0216] The reinjection pipe comprises a treated gas flow rate control member arranged to control the passage of the treated gas in the reinjection pipe 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 then reinjected when the installation is started. Once the installation has been started, that is to say when the predetermined temperature is reached, the hydrogen to be cooled is no longer diverted except in case of need (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 comprises at least one bypass pipe arranged to divert the hydrogen circulating in the gas circuit to be cooled 2 towards the cooling circuit 14. Thus, in this case the hydrogen coming from the gas circuit to be cooled 2 mixes with the hydrogen from the cycle of the cooling circuit 14 of the installation 1. The hydrogen coming from the cooling circuit 14 can thus be used in the cooling cycle during the start-up of the installation 1.

[0220] In [Fig.l], the installation 1 comprises two bypass pipes 17, 18. One of the bypass pipes 18, here called the first bypass pipe, comprises one end connected to the circuit of gas to be cooled 2 downstream of the first part 5 of the heat exchanger assembly and the cryogenic purifier 9 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 14 upstream of at least one compression member 15 in the direction of circulation 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 member 15 of the cycle gas.

[0221] The other bypass pipe (also called 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 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.

[0222] The installation 1 further comprises a reinjection pipe 19 for the treated gas, said reinjection pipe 19 comprising 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 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 set of heat exchangers, 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, in particular 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 having been purified and / or after having circulated 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 pipes 17, 18. One of the bypass pipes 18 (also called the first bypass pipe) has one end connected to the circuit of gas 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 circulation of the gas to be cooled, the other end of the first bypass pipe 18 is connected to the cooling circuit 14 upstream of at least one compression member 15 in the direction of circulation of the cycle gas. This embodiment is particularly advantageous when the cryogenic purifier 9 is not yet at a temperature cold enough 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 circuit of gas to be cooled 2 downstream of the second part 6 of the set of heat exchangers 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.

[0226] The installation 1 comprises a reinjection pipe 19 for the treated gas, said reinjection pipe comprises 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 fluid gas, the other end being connected to the gas circuit to be cooled 2 upstream of the first part 5 of the set of exchangers heat, in particular upstream of the first cold box 3 in the direction of circulation of the gas to be cooled.

[0227] Thus, in this embodiment, in particular 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 having circulated 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 comprises two bypass pipes 17, 18. One of the bypass pipes 18 (also called the first bypass pipe) has one end connected to the circuit of gas to be cooled 2 downstream of the first part 5 of the set 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, the other end of the first bypass pipe 18 is connected to the cooling circuit 14 upstream of at least one compression member 15 in the direction of circulation of the cycle gas.

[0229] The other bypass pipe (also called second bypass pipe 17) is connected by one of its ends to the circuit of gas to be cooled 2 downstream of the second part 6 of the set of heat exchangers 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.

[0230] In this embodiment, the installation 1 comprises a reinjection pipe 19 for the treated gas, said reinjection pipe comprising 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 set 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, in particular 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 having been purified by the cryogenic purifier 9 and / or after having circulated 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 downstream of the cryogenic purifier 9.

[0232] In the embodiment shown in [Fig.4], the installation 1 comprises two bypass lines 17, 18. One of the bypass lines (also called the first bypass line 18) has one end connected to the gas circuit at cooling 2 downstream of the first part of the set of 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, the other end of the first bypass pipe 18 is connected to the cooling circuit 14 upstream of at least one compression member 15 in the direction of circulation of the cycle gas.

[0233] The other bypass pipe 17 (also called second bypass pipe 26) is connected by one of its ends to the circuit of gas to be cooled 2 downstream of the second part 6 of the set of heat exchangers 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.

[0234] The installation 1 in this embodiment comprises a reinjection pipe 19 for the treated gas, said reinjection pipe comprising 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 set of heat exchangers and the cryogenic purifier 9, in particular in the first cold box 3.

[0235] Thus, in this embodiment, in particular 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 having been purified by the cryogenic purifier 9 and / or after having circulated 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 cryogenic purifier 9.

[0236] In the embodiments shown in Figures 5 and 6, the cooling circuit 14 comprises two cycle gas compression members, a low-pressure compressor 15a and a high-pressure compressor 15b. By low-pressure compressor, here is meant a compressor arranged to compress a gas from a pressure of approximately 1 bara to a pressure of between 5 and 10 bara. By high-pressure compressor here is meant a compressor arranged to compress a gas from a pressure of between 5 and 10 bara to a pressure of between 40 and 80 bara. The low-pressure compression member 15a and the high-pressure compression member 15b are mounted in series on the cooling circuit 14.The cooling circuit 14 comprises an expansion member 33 arranged to expand the gas to an intermediate pressure, in particular between 5 and 10 bara, and an expansion member 16 arranged to expand the gas until it reaches a low pressure, in particular between 1 and 2 bara. The expansion member arranged to expand the gas to an intermediate pressure is arranged on a bypass pipe 32 of the at least one expansion member arranged. to expand the cycle gas at low pressure, said bypass line 32 being arranged in the cooling circuit 14. In other words, when the cycle gas circulates in the bypass line 32, the cycle gas is expanded by the medium pressure expansion member 33, and when the cycle gas does not circulate in the bypass line 32, the cycle gas is expanded by the low pressure expansion member. The medium pressure expansion member 33 comprises for example at least one turbine and the low pressure expansion member 16 comprises for example at least one Joule-Thomson effect valve. The bypass pipe 32 is arranged to return the expanded cycle gas into the medium pressure expansion member 33 between the low pressure compression member 15a and the high pressure compression member 15b of the cooling circuit 14. Thus, the cooling circuit 14 is arranged to circulate a portion of the cycle gas in the bypass pipe 32 so that said portion of the gas passes through the at least one medium pressure expansion member 33 and another portion of the cycle gas towards the low pressure expansion member.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 the cycle gas passing through the 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 pipes 17, 18 for the hydrogen to be cooled. One of the bypass pipes (also called the first bypass pipe 18) has one end connected to the circuit of gas to be cooled 2 downstream of the first part 5 of the set of 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, the other end of the first bypass pipe 18 is connected to the cooling circuit 14 upstream of a low-pressure compression member 15a in the first cold box 3 in the direction of circulation of the cycle gas.

[0238] The other bypass pipe (also called second bypass pipe 17) is connected by one of its ends to the circuit of gas to be cooled 2 downstream of the second part 6 of the set of heat exchangers 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.

[0239] In this embodiment, the installation 1 comprises a reinjection pipe 19 for the treated gas, said reinjection pipe comprising two ends, one of its ends being connected to the cooling circuit 14 between the control member low pressure pressure 15a and the high pressure compression member 15b in the direction of circulation of the cycle gas, 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 in the direction of circulation of the gas to be cooled. This is particularly advantageous when the compressors are not oiled, in fact it is an energy-saving embodiment.

[0240] Thus, in this embodiment, in particular 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 having been purified by the cryogenic purifier 9 and / or after having circulated in the second part of the heat exchanger assembly to join the cooling circuit 14 upstream of the compression members 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 comprises four bypass lines 17, 18, 22, 23 for the hydrogen from the hydrogen circuit to be cooled 2. These lines will be called here the 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 circuit of gas to be cooled 2 downstream of the second part 6 of the set of heat exchangers 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 pipe 17 has one of its ends connected to the circuit of gas to be cooled 2, one end of which is connected to the circuit of gas 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 pipe 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 pipe 22 is connected by one of its ends 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 circulation of the gas to be cooled, in particular in the second cold box 4, the other end of the third bypass pipe 22 is connected to the cooling circuit 14 downstream of a medium pressure expansion member 33 and upstream of at least one high pressure compression member of the cooling circuit 14, in particular in the second cold box 4, in the direction of circulation of the cycle gas. In other words, the fourth bypass pipe 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 pipe 23 has one end connected to the circuit of gas to be cooled 2 between the cryogenic purifier 9 and the second part of the heat exchanger assembly, in particular in the first cold box 3, the other end of the bypass pipe is connected to the cooling circuit 14 in the first cold box 3 between a medium pressure expansion member 33 and a high pressure compression member of the cycle gas of the cryogenic cycle gas. In other words, the first bypass pipe 23 is connected to the cooling circuit 14 on the bypass pipe 32 of the cooling circuit 14 downstream of the medium pressure expansion member 33.

[0246] The installation 1 also comprises a reinjection pipe 19 for the treated gas, said reinjection pipe 19 comprising two ends, one of its ends being connected to the cooling circuit 14 downstream of the high-pressure compression member 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 set of heat exchangers, in particular upstream of the first cold box 3.

[0247] The compression members 15a, 15b may be, for example, volumetric compressors (screw and / or piston) that are dry or lubricated with oil. In the case where the compressors are lubricated, an oil removal system makes it possible to remove the oil mixed with the gas that passes through the compression member to prevent the oil from freezing in the heat exchangers or from being reinjected into the gas circuit to be cooled 2 via the at least one reinjection pipe. The oil removal system associated with the high-pressure compression member makes it possible to remove enough oil to avoid these problems of contamination by oil. 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, in particular 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 having been purified by the cryogenic purifier 9 and / or after having circulated 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.

[0249] In the embodiments shown in Figures 7 and 8, the bypass pipe is arranged to divert the hydrogen to be cooled to a third circuit 40 comprising a third compression member 56 and / or a third heating member 57. The third circuit 40 is distinct from the cooling circuit 14. In other words, the third compression member 56 is distinct from the compression member 15 of the cycle gas, and the third heating member 57 is distinct from the heating member of the cycle gas. In other words, the cooling device 13 does not include the third circuit 50, that is to say that the third circuit 40 is not part of the cooling circuit 14.

[0250] In the embodiment shown in [Fig.7], the installation 1 comprises two bypass pipes 41, 42. One of the bypass pipes, here called the first bypass pipe 41, is arranged to divert the gas to be cooled successively to a third circuit 40, in particular to a third heating member 57 separate from the heating member 20 of the cycle gas then to at least one compression member 15 of the cycle gas of the cooling circuit 14.Said first bypass pipe 41a one end is connected to the circuit of gas to be cooled 2 downstream of the first part 5 of the set of heat exchangers and of the cryogenic purifier 9 in the direction of circulation of the gas to be cooled, in particular upstream of the second set of heat exchangers, 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 the at least one cycle gas compression member of the cooling circuit 14 in the direction of circulation of the cycle gas, the bypass pipe 41 being arranged to divert the gas to be cooled successively towards the third heating member 57 then towards the cycle gas compression member of the cooling circuit 14.

[0251] The installation 1 comprises another bypass pipe, here called second bypass pipe 42. The second bypass pipe is connected by one of its ends to the third circuit 40 upstream of the third heating member 57 in the direction of circulation of the diverted gas in the third circuit 40, and possibly upstream of the third heating member 57, and the other end is connected to the circuit of gas to be cooled 2 downstream of the second part 6 of the set of heat exchangers.

[0252] The installation 1 further comprises a reinjection pipe 39 for the treated gas, said reinjection pipe comprising two ends, one of its ends being connected to the cooling circuit 14 downstream of the at least one compression member 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 set of heat exchangers, 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 pipes 52, 53. One of the bypass pipes 53, here called the first bypass pipe, has one end connected to the gas circuit to be cooled 2 downstream of the first part 5 of the set of 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, and its other end is connected upstream of a third compression member 56 separate from the at least one compression member 15 of the cycle gas of the cooling circuit 14, the third compression member 56 being in particular arranged on a third circuit 50 separate from the cooling circuit 14. The diverted compressed gas is then reheated by a third heating member 57 arranged on the third circuit 50.

[0254] The installation 1 comprises a second bypass pipe 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 circulation of the diverted gas in the third circuit 50.

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

Claims

Claims

1. Installation (1) for producing a cryogenic fluid, in particular liquefied hydrogen, comprising: - a gas circuit 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 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 circuit of gas 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 pipe (17, 18, 22, 23, 42, 41, 52, 53) for the gas to be cooled, said bypass pipe (17, 18, 22, 23, 42, 41, 52, 53) being arranged to divert the gas to be cooled from the circuit of gas to be cooled (2) towards at least one compression member (15) arranged to compress at least the diverted gas to be cooled and possibly towards a heating member (20) arranged to heat at least said diverted gas, said bypass pipe being in particular arranged upstream of the receiving system in the direction of circulation of the gas to be cooled, - at least one reinjection pipe (19, 39, 54) for the gas thus treated, said reinjection pipe 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 pipe (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 set of heat exchangers 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(s) 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 possibly a regeneration circuit configured to regenerate the cryogenic purifier (9), and arranged 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 the second part of the heat exchanger assembly is arranged 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 circulation 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 the at least one compression member depending on the temperature of the gas to be cooled measured by the temperature sensor.

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

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

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

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

8. Method for liquefying a gas, in particular hydrogen, using a hydrogen liquefaction installation (1), said method comprising during a start-up phase of said installation (1): - a step of supplying a gas to be cooled into a circuit of gas to be cooled (2), - a step of cooling said circuit of gas to be cooled (2) implemented by a cooling device comprising a cooling circuit (14) with a refrigeration cycle of a cycle gas, in particular hydrogen, - at least one step of diverting said gas to be cooled by a bypass pipe of said gas to be cooled towards a member compression device arranged to compress the diverted gas, and possibly to a heating member 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 re-injecting the gas thus treated into the gas circuit to be cooled (2) via a pipe for re-injecting said treated gas.

9. 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 pipe during a start-up phase of the installation (1).

10. Method according to 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 circuit of gas to be cooled (2) by the bypass pipe towards at least one member for compressing the cycle gas of the cooling circuit (14) arranged on the cooling circuit (14).

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