Equipment and method for liquefying hydrogen

Abstract

The present invention relates to a facility and a method for liquefying hydrogen, comprising a hydrogen circuit (2) having an upstream end (21) intended to be connected to a source (23) of gaseous hydrogen and a downstream end (22) connected to at least one reservoir (8), the facility (1) comprising a cryogenic box (18) housing a set of heat exchangers (3, 4, 5, 6) in heat exchange relationship with the hydrogen circuit (2), the facility (1) comprising a cooling device in heat exchange relationship with at least a part (3, 4) of the set of heat exchangers, the facility (1) comprising a pipe (12) for collecting boil-off gas, the pipe (12) having at least one upstream end connected to the reservoir (8) and / or to a tank (19) to be filled and a downstream end connected to the hydrogen circuit (2) inside the cryogenic box (18), the said downstream end of the collection pipe (12) comprising a part in heat exchange relationship with at least one heat exchanger (5, 6) of the set of heat exchangers (3, 4, 5, 6) before its connection to the hydrogen circuit (2).

Description

Technical Field

[0001] The present invention relates to equipment and a method for liquefying hydrogen.

[0002] More specifically, the present invention relates to equipment for liquefying hydrogen, including a hydrogen circuit having an upstream end designed to be connected to a source of gaseous hydrogen and a downstream end connected to at least one cryogenic storage tank for liquefied hydrogen of the equipment. The cryogenic storage tank is provided with a withdrawal duct configured to enable the supply of liquefied hydrogen to at least one tank to be filled, particularly a mobile tank. The equipment includes a cryogenic box housing a series of heat exchangers that exchange heat with the hydrogen circuit. The equipment includes a device for cooling by exchanging heat with at least a part of the series of heat exchangers configured to cool the hydrogen circuit. The cooling device includes a cryogenic cooler having a cycle for cooling the cycle gas in the operating circuit. The cycle gas includes at least one of hydrogen and helium. The operating circuit of the cooler includes a unit for compressing the cycle gas, a unit for cooling the cycle gas, a unit for expanding the cycle gas, and a unit for heating the cycle gas. The equipment relates to equipment including a duct for recovering vaporized gas, having at least one upstream end designed to be connected to a storage tank and / or a tank to be filled, and a downstream end connected to the hydrogen circuit.

Background Art

[0003] Vaporization ("boil-off") in trucks and tank filling systems within hydrogen liquefaction plants can lead to losses that can be on the order of 15% of production volume.

[0004] It will be understood that such losses due to vaporization can be recovered, reheated, recompressed after storage, and reinjected into the liquefaction unit. This requires a loss recirculation system and an appropriate size of the liquefaction unit.

[0005] Another solution to minimize the generation of these vaporized gases consists of supercooling the produced liquid hydrogen.

[0006] Known solutions for recovering these vaporized gases may have drawbacks as described below.

[0007] For example, part of the pressure reduction of the truck need not be directed towards the liquid storage of the facility by pressure balancing. This is because the pressure of the truck can be lower than the pressure of the storage. Thus, hydrogen is either lost or sent to the aforementioned recovery system.

[0008] During filling of the truck, as a result of insufficient driving pressure, low-temperature vapor may not be able to return to the liquid storage of the facility. These vapors are at risk of being lost.

[0009] Generally, the low temperature in the storage cannot compensate for all the additional heat generated during the filling operation of the truck. This causes the pressure in the storage to rise and hydrogen is lost.

[0010] There may also be cases where the return temperature of the vapor of the truck being filled is too high to be directly liquefied.

[0011] The pressure reduction is usually carried out intermittently. Between two filling operations of the truck, the line or duct is heated, and the gas returning to the liquefier becomes correspondingly hotter, making liquefaction more difficult.

[0012] When the liquid storage of the facility is relatively small, the pressure in the storage decreases during the filling operation of the truck. Therefore, it becomes necessary to use a device for pressurizing the liquid storage to vaporize the liquid hydrogen, which has to be re-liquefied later. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0013] An object of the present invention is to eliminate some or all of the above drawbacks of the prior art.

Means for Solving the Problem

[0014] For this purpose, the facility according to the invention, which further conforms to the general definition given in the above premise part, is substantially characterized in that the downstream end of the recovery duct is connected to the inside of the cryogenic box, and includes a part that exchanges heat with at least one heat exchanger of a series of heat exchangers before its connection to the hydrogen circuit.

[0015] Thereby, the vaporized gas can return to one of the heat exchangers of the cryogenic box of the liquefaction device at a temperature compatible with this heat exchanger.

[0016] Since the power required for hydrogen liquefaction is directly related to the pressure of gaseous hydrogen, this configuration enables the gas to be liquefied at a relatively high pressure.

[0017] This configuration makes it possible to keep or maintain the pressure in the heat exchanger that cools this recovered vaporized gas (during liquefaction) as high as possible while limiting the pressure increase required when the pressure in the reservoir or truck supplying this vaporized gas is low.

[0018] This structure does not significantly affect the performance of the liquefaction device.

[0019] Furthermore, embodiments of the present invention may include one or more of the following features: - The downstream end of the recovery duct includes a unit for expanding the flow of the vaporized gas, and this unit is preferably located between a part that exchanges heat with at least one heat exchanger of a series of heat exchangers and the connection to the hydrogen circuit; - The series of heat exchangers includes a plurality of heat exchangers positioned in series between the upstream end and the downstream end of the hydrogen circuit, and the connection of the downstream end of the recovery duct to the hydrogen circuit is located downstream of the first passage of the hydrogen circuit in the last heat exchanger in series; - The first passage of the hydrogen circuit in the last heat exchanger in series includes a section for catalytic reaction of hydrogen configured to convert at least a part of ortho-hydrogen to para-hydrogen; - Downstream of the connection part, the hydrogen circuit provides a second passage in the last heat exchanger; - The second passage in the last heat exchanger does not include a section for catalytic reaction of ortho-hydrogen to para-hydrogen; - Downstream of the second passage in the last heat exchanger, the hydrogen circuit includes a unit for expanding the flow of hydrogen, and the expansion unit includes at least one of an expansion valve and a turbine; - Upstream of the connection part to the hydrogen circuit, the downstream end of the recovery duct includes a catalytic reaction section configured to convert at least a part of para-hydrogen to ortho-hydrogen; - The downstream end of the recovery duct includes a bypass part and a series of valves configured to ensure or not ensure the passage of the flow of vaporized gas in the catalytic reaction section; - The downstream end of the recovery duct includes a bypass part and a series of valves configured to ensure or not ensure the passage of the flow of vaporized gas in the catalytic reaction section; - The recovery duct includes a compression unit such as a cryogenic compressor; - The recovery duct includes a first upstream end connected to a reservoir and a second upstream end designed to be connected to a mobile tank; - The first and second upstream ends of the recovery duct are connected to the downstream end of the recovery duct via two separate branch pipes of the duct respectively, and the compression unit is located in the duct branch pipe of the second upstream end of the recovery duct.

[0020] The present invention also relates to a method for liquefying hydrogen using a facility according to any one of the above or below features. This method includes steps of recovering vaporized gas through a recovery duct, cooling the recovered vaporized gas in a cryogenic box, expanding the vaporized gas in the cryogenic box, and mixing the expanded vaporized gas with the flow of hydrogen to be cooled.

[0021] According to other possible specific features, - The method includes at least one of the following steps: expanding a mixture of vaporized gas and a stream of hydrogen to be cooled, expanding a mixture of vaporized gas and a stream of hydrogen to be cooled.

[0022] The present invention may also relate to any alternative method or apparatus including any combination of the above or below features within the scope of the claims.

[0023] Other specific features and advantages will become apparent by reading the following description provided with reference to the drawings.

[0024] The present invention will be better understood by reading the following description provided merely by way of example with reference to the accompanying drawings.

Brief Description of the Drawings

[0025]

Figure 1

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[0026] Throughout the figures, the same reference numerals are associated with the same elements.

[0027] In this detailed description, the following embodiments are examples. In this description, one or more embodiments are referred to, but this does not mean that the features are applicable only to a single embodiment. The simple features of different embodiments can also be combined and / or exchanged to provide other embodiments.

[0028] The hydrogen liquefaction equipment 1 shown in [FIG. 1] includes a hydrogen circuit 2 to be cooled / liquefied. This hydrogen circuit 2 has an upstream end 21 designed to be connected to a source 23 of gaseous hydrogen and a downstream end 22 connected to at least one cryogenic reservoir 8 for the liquefied hydrogen produced by the equipment 1.

[0029] The source 23 of gaseous hydrogen may include an electrolyzer, a gaseous hydrogen network, and / or any other hydrogen production device.

[0030] The cryogenic reservoir 8 includes, for example, a vacuum-insulated cryogenic tank and is provided with at least one extraction duct 11 configured to enable the supply of liquefied hydrogen to at least one tank 19 (for example, a cryogenic tank 19 transported by truck) to be filled.

[0031] The installation 1 includes a cryogenic box 18, i.e. a thermally insulated, preferably sealed cryogenic closed container that houses at least part of a cryogenic liquefaction unit forming a liquefaction device 31.

[0032] The cryogenic box 18 houses in particular a series of heat exchangers 3, 4, 5, 6 for heat exchange, and the cryogenic part of the hydrogen circuit 2 exchanges heat with these heat exchangers 3, 4, 5, 6.

[0033] The installation 1 also includes a cooling device that exchanges heat with at least part 3, 4 of a series of heat exchangers, and this device is configured to generate the cold heat used to cool the hydrogen circuit 2.

[0034] This cooling device preferably includes a cryogenic cooler 7 having a cycle for cooling the cycle gas in the operating circuit. In other words, the operating circuit is subjected to a thermodynamic cycle that transports the cycle gas to the low-temperature end at cryogenic temperature so as to provide low-temperature cooling power.

[0035] The cycle gas includes, for example, at least one of hydrogen and helium. The operating circuit of the cooler 7 includes a unit 9 (one or more compressors in series and / or in parallel) for compressing the cycle gas, units 3, 4 for cooling the cycle gas, a unit 10 (turbine and / or expansion valve) for expanding the cycle gas, and units 6, 5, 4, 3 for heating the cycle gas. The units for cooling and heating the gas may include heat exchangers, in particular countercurrent heat exchangers that ensure simultaneous heating and cooling of the cycle gas in the operating circuit.

[0036] The installation 1 also includes at least one vapor recovery duct 12. This recovery duct 12 has at least one upstream end connected to the reservoir 8 and / or an upstream end designed to be connected to the tank 19 to be filled, and a downstream end connected to the hydrogen circuit 2 for recovering the vapor for the purpose of mixing it with the liquefied and produced liquid hydrogen.

[0037] As shown in [[FIG. 2]], the downstream end of the recovery duct 12 is connected to the hydrogen circuit 2 inside the low-temperature box 18. Further, before being connected to the hydrogen circuit 2, the downstream end of the recovery duct 12 exchanges heat with at least one of the heat exchangers 5, 6 of a series of heat exchangers 3, 4, 5, 6 for the purpose of cooling.

[0038] As shown, the series of heat exchangers 3, 4, 5, 6 of the low-temperature box preferably includes a plurality of heat exchangers positioned in series between the upstream end 21 and the downstream end 22 of the hydrogen circuit 2. The connection of the downstream end of the recovery duct 12 to the hydrogen circuit 2 is located, for example, downstream of the first passage of the hydrogen circuit 2 in the last heat exchanger 6 in series.

[0039] As shown, the first passage of the hydrogen circuit 2 in the last heat exchanger 6 preferably includes a section 29 for catalytic reaction of hydrogen, which is configured to convert at least a part of ortho-hydrogen to para-hydrogen. Downstream of the first passage in the catalytic reaction section 29 of the heat exchanger 6, the hydrogen circuit 2 preferably includes an expansion unit 30 such as an expansion valve.

[0040] Similarly, the downstream end of the recovery duct 12 preferably includes a unit 20 for expanding the flow of vaporized gas, which is located between the portion exchanging heat with the heat exchangers 5, 6 and the connection to the hydrogen circuit 2 among the series of heat exchangers.

[0041] As shown, downstream of the connection, the hydrogen circuit 2 receiving the cooled and expanded vaporized gas can perform a second passage in the last heat exchanger 6 for the purpose of auxiliary cooling. This second heat exchanger is preferably arranged in another section of the heat exchanger 6 that does not include a catalytic reaction section.

[0042] As shown, downstream of this second passage in the last heat exchanger 6, the hydrogen circuit 2 may include a unit 23 for expanding the flow of hydrogen. This expansion unit 23 is, for example, the last expansion unit within the cryogenic box and includes, for example, an expansion valve and / or a cryogenic expansion turbine. The fluid expanded in this way can be liquefied and then supplied to the cryogenic storage via an appropriate duct.

[0043] This configuration makes it possible to prevent the expansion of gaseous hydrogen which may tend to heat the gaseous hydrogen. According to the above configuration, the recovered gaseous hydrogen is expanded in two stages within the liquefaction device. First, it is at the outlet of the last catalytic heat exchanger 6, and then it is during the second passage within the heat exchanger 6 without catalytic conversion and is finally expanded to the final pressure level designated for the storage 8.

[0044] [Figure 1] and [Figures 3] to [Figure 8] show different configurations or operations that can be implemented by the installation 1.

[0045] As shown, the recovery duct 12 preferably includes a first upstream end connected to the upper end of the storage 8 and a second upstream end designed to be connected to the upper end of the mobile tank 19. For example, the first and second upstream ends of the recovery duct 12 are connected to the downstream end of the recovery duct via two separate duct branch pipes 121, 122 respectively. These two branch pipes 121, 122 may be provided with respective valves 221, 222.

[0046] Furthermore, the downstream end 22 of the hydrogen circuit may include two ends respectively connected to the lower and upper parts of the storage via respective valves 201, 202 for filling the storage 8 in its liquid phase or its gas phase.

[0047] Furthermore, as shown, the extraction duct 11 has an upstream end connected to the reservoir 8 (lower part), preferably an upstream end provided with a valve 111, and two downstream ends. The first downstream end provided with a valve 112 can be designed to be detachably connected to a tank (lower part) filled with liquid. The second downstream end of the extraction duct 11 may be provided with a valve 113 and can be connected to the second upstream end (branch pipe 122) of the gas recovery duct 12.

[0048] Due to the fluid connection between the extraction duct 11 and the branch pipe 122, liquid can be injected into the tank 19 at its upper part (for example, filling in the rain).

[0049] In the different configurations shown, the closed valves are shown in black and the open valves are shown in white.

[0050] In the configuration shown in [Figure 1], there is no mobile tank to be filled.

[0051] Hydrogen from the source 23 is liquefied by the liquefier 31 and distributed to the reservoir 8 through the pipes of the circuit 2. The gas recovery valve 222 from the mobile tank is closed. Hydrogen can be supplied to the reservoir at its lower part. The hydrogen supplied by the liquefier 31 can maintain the pressure of the reservoir 8 and be supercooled to withstand the heat input. The pressure of the reservoir 8 can be adjusted by the valves 201 and 202 that allow filling from the bottom and / or the top. As shown, the valve 221 at the first downstream end of the vapor recovery duct from the storage part 8 can be opened to keep this duct 121, 12 at a low temperature.

[0052] In the configuration of [Figure 3], a mobile tank 19 to be filled is connected to the first downstream end of the extraction duct 11. This tank 19 is also connected to the second upstream end (branch pipe 122) of the recovery duct 12.

[0053] After the tank 19 is connected to the extraction duct 11 and the gas recovery duct 12, the pressure in the tank 19 (e.g., 3 to 10 bar) is reduced to a level below the pressure P8 in the reservoir 8 (e.g., several millibars lower than P8). This is done to enable the tank 19 to be filled with liquid from the reservoir by the pressure difference (without using a pump).

[0054] The hydrogen in the tank 19 is generally mainly gas (1 to 10% liquid phase), and the temperature is 100 K to 25 K. The first part of the recovered high-temperature hydrogen can be sent to the recovery system 32 via a parallel line to which the valve 322 is attached.

[0055] When the temperature in the tank 19 drops to a determined level, e.g., 50 K to 30 K, the gas can be sent to the liquefier (the valve 222 is opened).

[0056] This gaseous hydrogen is liquefied by the liquefier 31 as described above and can be returned to the reservoir 8 provided that the pressure in the tank 19 exceeds the pressure in the reservoir 8 (plus the losses of the load in the circuit).

[0057] To complete the depressurization of the tank 19, it may be necessary to make its pressure lower than the pressure in the reservoir 8. Several possibilities are conceivable. In the first option, the depressurization of the tank 19 can be carried out towards the recovery system 32 (see [Figure 4]).

[0058] According to another possibility, the pressure can be balanced between the tank 19 and the reservoir 8 (see [Figure 5]: the valves 222 and 221 are opened), and then the reservoir is pressurized by the liquefier (the valve 201 is opened, see [Figure 5]). In other words, the gas is transferred from the tank 19 to the reservoir via the branch pipe 122 of the recovery duct 12 and then the branch pipe 121.

[0059] At the end of this first sequence, the tank 19 has reached a pressure P19 lower than the pressure P8 of the reservoir 8.

[0060] Next, as shown in FIG. 6, the tank 19 can be filled with liquid. Liquid hydrogen can be transferred from the reservoir 8 to the upper part of the tank 19 via the valve 113 of the branch pipe connected to the extraction duct 11 and the gas recovery duct.

[0061] The liquid coming from the reservoir 8 can be brought to a low temperature sufficient to maintain the pressure P19 in the tank 19 by condensing the vapor there. The pressure in the reservoir 8 can be maintained by injecting the liquid hydrogen coming from the liquefier into the vapor phase of the reservoir (opening the valve 221 and filling from the top via the branch pipe 121 of the gas recovery duct 12). This hydrogen can be from the hydrogen circuit 2 expanded and heated in the heat exchanger. Thus, during this stage, instead of injecting heat into the reservoir 8 via a pressurizing unit ("PBU"), the corresponding cold air can be recovered inside the liquefier 31.

[0062] At the end of this sequence, the tank 19 may still have a pressure P19 close to the pressure P8 of the reservoir 8. The tank 19 is filled to more than half of its capacity (e.g., 85% - 95% of its capacity), but its pressure should preferably be reduced so that it can be transported to a remote location without losing hydrogen during movement.

[0063] The pressure of the traveling tank 19 can vary depending on local regulations.

[0064] This pressure reduction can be performed, for example, by degassing to the recovery system 32 (the valve 322 is opened). The pressure of the tank 19 can be, for example, 1.5 bar. At the same time, the facility can continue to control the pressure in the reservoir 8 by injecting supercooled liquid hydrogen at the top and / or bottom of the reservoir 8, for example, by controlling the valves 202 and 201. See [FIG. 7].

[0065] [Fig. 8] shows a modified embodiment that differs from [Fig. 1] only in that the branch pipe 122 of the recovery duct 12 designed to recover the vapor gas from the tank 19 includes a compression unit 24 such as a cryogenic compressor (a low-temperature compressor configured to compress vapor at a temperature of 25 to 100 K). As shown, a bypass duct 124 of the compressor 24 and a series of valves 224, 324 can be provided to ensure or not ensure the passage of all or part of the flow entering the compressor 24.

[0066] This compression unit 24 improves the recovery of the vapor from the tank 19 through the duct 12 for recovering the vapor to the liquefier 31.

[0067] With this compression unit 24, it becomes possible to increase the pressure of the hydrogen vapor recovered for the purpose of recovery in the reservoir 8 and / or the liquefier 31 at a stage where the pressure available in the tank 19 is not sufficient to reliably perform this transfer due to the pressure difference. The advantage of the cryogenic compressor 24 compared to a conventional compressor at ambient temperature is its size, which is reduced due to the higher density of cryogenic hydrogen. The low temperature of the hydrogen is maintained during compression, and the compressed cryogenic hydrogen can be easily recovered to the reservoir 8 or the liquefier 31 and liquefied again.

[0068] [Fig. 8] has a configuration corresponding to that of [Fig. 1]. The hydrogen in circuit 2 is liquefied by the liquefier 31 and distributed to the reservoir 8. This hydrogen can control and maintain the pressure in the reservoir 8 and be supercooled to withstand the heat input. This pressure in the reservoir 8 can be adjusted via valves 202, 201 (filling from the top / bottom). As shown, the valve 221 in the branch pipe for recovering the vapor gas from the reservoir 8 can be opened to keep this line at a low temperature. The valves 222, 322 in the branch pipes for recovering the vapor gas from the tank 19 are closed. The compressor 24 is preferably stopped.

[0069] [ Fig. 3 。It should be noted that in this embodiment shown, although the extraction duct 11 is not connected to the upper part of the tank (via the branch pipe 122), it can be understood that it can be connected.

[0070] After the tank is connected to the extraction duct 11 and the gas recovery ducts 12, 122, the pressure in the tank 19 (e.g., 3 - 10 bar) can be reduced to below the pressure in the reservoir 8. In principle, the hydrogen in the tank 19 is mainly in the gaseous state (1 - 10% liquid phase) and is at a temperature of, for example, 100K - 25K. The first part of the recovered hot hydrogen can be sent to the recovery system 32 (when the valve 322 is opened). When the temperature of the gas in the tank 19 drops (e.g., 50K - 30K), the recovered gas can be sent to the liquefaction device 31 (when the ducts 12, valves 222, 224 are opened). This hydrogen is liquefied as described above (by passing through the heat exchanger 6 and expanding) and is supplied to the reservoir 8 on the condition that the pressure in the tank 19 is kept higher than the pressure in the reservoir 8 (plus the loss of the load of the associated circuit). In this first pressure reduction stage, the compressor 24 is preferably not used but can be cooled by the vapor returning to the liquefaction device 31.

[0071] As shown in [Figure 10], in order to complete the pressure reduction of the tank 19, this pressure can be reduced to below the pressure in the reservoir 8. The compressor 24 can be used to suck the vapor from the tank 19 and send it to the reservoir 8. At this stage, the return to the liquefaction device 31 can be closed. The pressure in the reservoir 8 can still be adjusted by the valves 202, 201. Thus, gas is transferred from the tank 19 to the reservoir 8.

[0072] When this step is completed, the tank 19 has reached a pressure below the pressure in the reservoir 8. This represents the main part of filling the tank 19 with liquid. Liquid hydrogen is transferred from the reservoir 8 to the tank 19It is transferred to. The pressure of the storage device 8 can be maintained by injecting hydrogen coming from the liquefaction device 31 (valves 201 and / or 202). The pressure of the tank 19 can be maintained below the pressure of the storage device 8 by the compressor 24. Please refer to [Figure 10].

[0073] At the end of this step, the tank 19 can still be at a pressure close to that of the storage device 8. The filling level of the tank 19 is relatively high (e.g., 85% - 95%), but in order to be transported to a remote location and not lose hydrogen during movement, it may be necessary to reduce its pressure. This pressure during driving can vary depending on local regulations. The compressor 24 can be used to reduce this pressure in the tank 19 to the required starting pressure (without using the valve 332 towards the recovery system or by avoiding loss of hydrogen during movement). The gas in the tank 19 is pumped to the storage section 8 (please refer to [Figure 12]).

[0074] The cryogenic compressor 24 can also be used to reduce the pressure of the storage device 8 without supplying supercooled hydrogen. Thereby, the production capacity of the liquefaction device is improved.

[0075] [Figure 13] shows a modified embodiment of the circuit for returning the vaporized gas recovered in the cryogenic box 18 of the liquefaction device 31. For simplicity, in [Figure 13], only the cryogenic box 18 and a part of the circuit are shown. The embodiment of [Figure 13] is different from the embodiment of [Figure 2] in that the downstream end of the recovery duct 12 includes a catalytic reaction section 25 (e.g., a catalytic converter) configured to convert at least a part of the parahydrogen into orthohydrogen upstream of the connection to the hydrogen circuit 2.

[0076] Furthermore, the recovery duct 12 includes a bypass portion 26 and a series of valves 27, 28 configured to ensure or not ensure the passage of the vaporized gas flow to the catalytic reaction section 25.

[0077] The specifications required for the hydrogen liquefaction device 31 are to achieve a minimum conversion rate of approximately 95% para at the outlet of the liquefaction device. The presence of catalysts in the last heat exchangers 5, 6 generally enables a conversion rate of 98% - 100% depending on the hydrogen pressure.

[0078] The gaseous hydrogen returning from the tank 19 to be filled is obtained by the vaporization of the liquid and is generally composed of para-type hydrogen at a ratio of 98% - 100%.

[0079] In certain cases, since it may interfere with the operation of the liquefaction device 31, the facility 1 is not suitable for the recovery of hydrogen vapor that is too hot.

[0080] This recovered vapor can be cooled by utilizing the reverse ortho-to-para conversion implemented in the liquefaction device with respect to the flow in the hydrogen circuit 2.

[0081] Thus, for example, these recovered vaporized gases can have a temperature of 50K - 25K. The higher this temperature, the further hydrogen is away from the equilibrium point at this temperature (20K in the case of 98% para hydrogen), and hydrogen is further cooled by the conversion from para to ortho.

[0082] Thus, the vapor is converted from para-type to ortho-type, liquefied in the heat exchanger 6 / expansion device 20, mixed with the hydrogen in the circuit 2, and then supplied to the reservoir 8 (as described above).

[0083] The use of this type of catalytic converter 25 is generally necessary only when the gaseous hydrogen reaches a sufficiently high temperature (e.g., at the start of the pressure reduction of the tank 19 to be filled) and is under sufficient pressure (usually 3 - 10 bar). The bypass systems 26, 27, especially the valves, can be configured to ensure that the gas passes through the conversion catalyst according to the return temperature of the gas, which can be measured by the temperature sensor 33 in the recovery duct 12.

[0084] Thus, when the measured temperature becomes sufficiently low or the pressure in the recovery duct drops (at the end of the pressure reduction of the tank 19), the Valve28 is closed and the direct supply valve 27 of the exchanger 6 is opened, reducing the loss of the load of the system.

[0085] By controlling the pressurization of the tank 19, the flow related to the capacity of the liquefaction device is restricted (control of the outlet temperature of the heat exchanger for the reliquefied gas may be provided).

[0086] It will be understood that this embodiment may be applied to the above embodiments and steps.

[0087] Furthermore, the above examples are not limiting. Thus, for example, the facility may include a plurality of storage vessels 8 and / or a plurality of filling ducts 11 and a recovery duct 12 for the vaporized gas.

[0088] Particularly when a plurality of tanks are processed simultaneously, the cryogenic compressor 24 may be positioned in parallel with the recovery duct to transfer the gas to the liquefaction device.

Claims

Claim 1 A facility for liquefying hydrogen, comprising a hydrogen circuit (2) having an upstream end (21) designed to be connected to a source (23) of gaseous hydrogen and a downstream end (22) connected to at least one cryogenic storage tank (8) for liquefied hydrogen of the facility, the cryogenic storage tank (8) being provided with a withdrawal duct (11) configured to enable the supply of liquefied hydrogen to at least one tank (19), in particular a mobile tank, to be filled, the facility (1) including a cryogenic box (18) housing a series of heat exchangers (3, 4, 5, 6) that exchange heat with the hydrogen circuit (2), the facility (1) including means for cooling by exchanging heat with at least a part (3, 4) of the series of heat exchangers, which are configured to cool the hydrogen circuit (2), the cooling means including a cryogenic cooler (7) having a cycle for cooling a cycle gas in an operating circuit, the cycle gas including at least one of hydrogen and helium, the operating circuit of the cooler (7) including a unit (9) for compressing the cycle gas, a unit (3, 4) for cooling the cycle gas, a unit (10) for expanding the cycle gas, and a unit (6, 5, 4, 3) for heating the cycle gas, the facility (1) including a duct (12) for recovering vaporized gas having at least one upstream end designed to be connected to the storage tank (8) and / or to a tank (19) to be filled and a downstream end connected to the hydrogen circuit (2), inside the cryogenic box (18), the downstream end of the recovery duct (12) including a part that exchanges heat with at least one heat exchanger (5, 6) of the series of heat exchangers (3, 4, 5, 6) of the cryogenic box (18), which are positioned in series between the upstream end (21) and the downstream end (22) of the hydrogen circuit (2) before its connection to the hydrogen circuit (2), the hydrogen circuit (2) making a first pass in the last heat exchanger (6) in series, and downstream of the first pass section, the hydrogen circuit (2) including an expansion unit (30), such as an expansion valve, for example, the connection of the downstream end of the recovery duct (12) to the hydrogen circuit (2) isLocated downstream of the first passage of the hydrogen circuit (2) in the last heat exchanger (6) of the series and downstream of the expansion unit (30), downstream of the connection part, the hydrogen circuit (2) which has received the cooled and expanded vaporized gas makes a second passage in the last heat exchanger (6) for the purpose of auxiliary cooling, and downstream of the second passage in the last heat exchanger (6), the hydrogen circuit (2) includes a unit (23) for expanding the flow of hydrogen, and the downstream end of the recovery duct (12) is located between the part that exchanges heat with at least one of the heat exchangers (5, 6) of the series of heat exchangers (3, 4, 5, 6) and the connection part to the hydrogen circuit (2), and includes a unit (20) for expanding the flow of vaporized gas, a facility. Claim 2 The first passage of the hydrogen circuit (2) in the last heat exchanger (6) in series is configured to convert at least a part of ortho-hydrogen into para-hydrogen, and includes a section (29) for catalytic reaction of the hydrogen. The facility according to claim 1, characterized in that it comprises a section (29). Claim 3 The second passage into the last heat exchanger (6) does not include a section for catalytically reacting the ortho-hydrogen to para-hydrogen. The facility according to claim 1 or 2, characterized in that it does not include such a section. Claim 4 The unit (23) for expanding the hydrogen circuit (2) located downstream of the second passage in the last heat exchanger (6) includes at least one of an expansion valve and a turbine. The facility according to any one of claims 1 to 3, characterized in that it includes at least one of them. Claim 5 Upstream of the connection to the hydrogen circuit (2), the downstream end of the recovery duct (12) includes a catalytic reaction section (25) configured to convert at least a part of the para-hydrogen into ortho-hydrogen. The facility according to any one of claims 1 to 4, characterized in that it includes such a section. Claim 6 The downstream end of the recovery duct (12) includes a bypass portion (26) and a series of valves (27, 28) configured to ensure or not ensure the passage of the vaporized gas flow in the catalytic reaction section (25). The facility according to claim 5, characterized in that it includes them. Claim 7 The recovery duct (12) includes a compression unit (24) such as a cryogenic compressor. The facility according to any one of claims 1 to 6, characterized in that it includes such a unit. Claim 8 The recovery duct (12) includes a first upstream end connected to the reservoir (8) and a second upstream end designed to be connected to a mobile tank (19). The facility according to any one of claims 1 to 7, characterized in that it includes them. Claim 9 The first and second upstream ends of the recovery duct (12) are each connected to the downstream end of the recovery duct (12) via two separate branch pipes of the duct, and the compression unit (24) is located in the duct branch pipe of the second upstream end of the recovery duct (12). The facility according to claim 7 or 8, characterized in that it is as described. Claim 10 A method for liquefying hydrogen using the facility according to any one of claims 1 to 9, comprising the steps of recovering vapor gas through the recovery duct (12), cooling the recovered vapor gas in the cryogenic box (18), expanding the vapor gas in the cryogenic box (18), and mixing the expanded vapor gas with the flow of hydrogen to be cooled.

11. The method for liquefying hydrogen according to claim 10, comprising at least one of the steps of expanding a mixture of the vapor gas and the flow of hydrogen to be cooled, and expanding the mixture of the vapor gas and the flow of hydrogen to be cooled.

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