Facility and method for hydrogen liquefaction

Abstract

The invention relates to a plant and a method for hydrogen liquefaction, comprising a hydrogen circuit (2) having an upstream end (21) intended to be connected to a gaseous hydrogen source (23) and a downstream end (22) connected to at least one reservoir (8), the plant (1) comprising a cold box (18) housing a set of heat exchangers (3, 4, 5, 6) in heat exchange relationship with the hydrogen circuit (2), the plant (1) comprises cooling means in heat exchange relationship with at least a portion of the heat exchangers (3, 4) of the set of heat exchangers, the plant (1) comprising a conduit (12) for collecting the flash vapor, equipped with at least one upstream end connected to the reservoir (8) and / or the tank (19) to be filled and a downstream end connected to the hydrogen circuit (2) within the cold box (18), the downstream end of the collection duct (12) comprises, before its junction with the hydrogen circuit (2), a portion in heat exchange relationship with at least one heat exchanger (5, 6) of the set of heat exchangers (3, 4, 5, 6).

Description

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

[0002] More specifically, the invention relates to a facility for liquefaction of hydrogen, the facility comprising a hydrogen circuit having an upstream end designed to be connected to a gaseous hydrogen source and a downstream end connected to at least one liquefied hydrogen cryogenic storage of the facility, the cryogenic storage being provided with an extraction pipeline configured to allow the supply of liquefied hydrogen to at least one tank to be filled, in particular an on-board tank, the facility comprising a cold box housing a series of heat exchangers for heat exchange with the hydrogen circuit, the facility comprising cooling means for heat exchange with at least a part of the heat exchangers in the series, the cooling means The invention is configured to cool a hydrogen circuit, wherein the cooling device comprises a low-temperature refrigerator having a refrigeration cycle for a circulating gas in a working circuit, wherein the circulating gas comprises at least one of the following: hydrogen and helium. The working circuit of the refrigerator comprises a unit for compressing the circulating gas, a unit for cooling the circulating gas, a unit for expanding the circulating gas, and a unit for heating the circulating gas. The facility comprises a pipeline for recovering boil-off gas, wherein the pipeline is provided with at least one upstream end connected to a storage device and / or designed to be connected to a storage tank to be filled, and a downstream end connected to the hydrogen circuit.

[0003] In the systems used to fill tank trucks and storage tanks in hydrogen liquefaction plants, boil-off (flashing) can cause losses of potentially up to 15% of production.

[0004] It will be appreciated that these evaporation losses can be recovered, reheated, recompressed after storage, and reinjected into the liquefier. This requires a system for loss recycling and a liquefier of adequate size.

[0005] Another solution to minimize the production of these boil-off gases consists in subcooling the produced liquid hydrogen.

[0006] Known solutions for recovering these boil-off gases may have disadvantages as described below.

[0007] Since the pressure of the tanker can become lower than the pressure of the storage, there is no need for partial depressurization of the tanker towards the liquid storage of the facility by pressure equalization. The hydrogen is thus lost or sent to a recovery system as described above.

[0008] During the filling of a tank truck, it may happen that the cold vapors can no longer flow back to the facility's liquid storage due to lack of driving pressure. These vapors are susceptible to being lost.

[0009] Generally speaking, the low temperatures existing in the storage tanks cannot compensate for all the additional heat caused by the filling operation of the tank trucks. This causes an increase in pressure in the storage tanks and a loss of hydrogen.

[0010] The return temperature of the vapor from the tank car being filled may be too high to be liquefied directly.

[0011] The depressurization is usually intermittent. The line or pipeline heats up between tanker filling operations, so the gas returning to the liquefier is correspondingly hotter and more difficult to liquefy.

[0012] When the liquid storage of the facility is relatively small, the pressure of the storage drops during the filling operation of the tanker truck. This makes it necessary to use a device for pressurizing the liquid storage in order to boil off the liquid hydrogen that will later need to be reliquefied.

[0013] The object of the present invention is to obviate some or all of the above-identified disadvantages of the prior art.

[0014] To this end, the essential feature of the plant according to the invention and corresponding to the general definition given in the above preamble is that the downstream end of the recovery pipe is connected to the interior of the cold box and, before its connection with the hydrogen circuit, comprises a portion for heat exchange with at least one of the series of heat exchangers.

[0015] This allows the boil-off gas to flow back to one of the exchangers of the liquefier cold box at a temperature compatible with that exchanger.

[0016] Since the power required to liquefy hydrogen is directly related to the pressure of the gaseous hydrogen, this configuration makes it possible to liquefy the gas at relatively high pressures.

[0017] This configuration makes it possible to retain or maintain the highest possible pressure (at the moment of liquefaction) in the heat exchanger cooling the recovered boil-off gas, while limiting the pressure increase required in the event of low pressure in the storage tank or tanker supplying the boil-off gas.

[0018] This architecture has little impact on the capacity of the liquefier.

[0019] Additionally, embodiments of the present invention may include one or more of the following features:

[0020] - the downstream end of the recovery conduit comprises a unit for expanding the boil-off gas stream, preferably situated between the portion in heat exchange with at least one of the series of heat exchangers and the connection with the hydrogen circuit;

[0021] - the series of heat exchangers comprises a plurality of heat exchangers positioned in series between the upstream end and the downstream end of the hydrogen circuit, the connection of the downstream end of the recovery pipe to the hydrogen circuit being located downstream of the first passage of the hydrogen circuit in the final heat exchanger of the series;

[0022] - the first passage of the hydrogen circuit in the final heat exchanger of the series comprises a section for catalyzing hydrogen configured to carry out conversion of at least a portion of the orthohydrogen into parahydrogen;

[0023] - downstream of this connection, the hydrogen circuit provides a second passage in the final heat exchanger;

[0024] - the second pass in the final heat exchanger does not include a section for catalyzing orthohydrogen to parahydrogen;

[0025] - downstream of the second passage in the final heat exchanger, the hydrogen circuit comprises a unit for expanding the hydrogen flow, said expansion unit comprising at least one of the following: an expansion valve, a turbine;

[0026] - upstream of the connection with the hydrogen circuit, the downstream end of the recovery conduit comprises a catalytic section configured to perform a conversion of at least part of the parahydrogen into orthohydrogen;

[0027] - the downstream end of the recovery conduit comprises a bypass portion and a series of valves configured to ensure that the boil-off gas flows through or not through the catalytic section;

[0028] - the downstream end of the recovery conduit comprises a bypass portion and a series of valves configured to ensure that the boil-off gas flows through or not through the catalytic section;

[0029] - the recovery pipeline includes a compression unit, such as a cryogenic compressor;

[0030] - the recovery pipe comprises a first upstream end connected to the reservoir and a second upstream end designed to be connected to an onboard tank;

[0031] The first upstream end and the second upstream end of the recovery pipe are connected to the downstream end of the recovery pipe via two different pipe branches, respectively, and the compression unit is located in the pipe branch of the second upstream end of the recovery pipe.

[0032] The present invention also relates to a method for liquefying hydrogen using a facility according to any of the above or following characteristics, the method comprising the steps of recovering boil-off gas via a recovery conduit, cooling the recovered boil-off gas in a cold box, expanding the boil-off gas in the cold box, and mixing the expanded boil-off gas with a hydrogen stream to be cooled.

[0033] According to other possible specific characteristics:

[0034] The method comprises at least one of the following: a step of expanding a mixture of boil-off gas and a hydrogen stream to be cooled, a step of expanding a mixture of boil-off gas and a hydrogen stream to be cooled.

[0035] The invention may also relate to any alternative method or apparatus comprising any combination of the above or below features within the scope of the claims.

[0036] Other particular features and advantages will become apparent from a reading of the following description given with reference to the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The invention will be better understood from a reading of the following description given by way of example only with reference to the accompanying drawings, in which:

[0038] [ Figure 1 ] is a schematic partial view illustrating a first example of the structure and operation of the facility in a first configuration;

[0039] [ Figure 2 ] is a schematic partial view showing details of the structure and operation of such a facility according to a first possible embodiment;

[0040] [ Figure 3 ] is a schematic partial view showing the first example of the facility in a second configuration;

[0041] [ Figure 4 ] is a schematic partial view showing this first example of the facility in a third configuration;

[0042] [ Figure 5 ] is a schematic partial view showing this first example of the facility in a fourth configuration;

[0043] [ Figure 6 ] is a schematic partial view showing this first example of the facility in a fifth configuration;

[0044] [ Figure 7 ] is a schematic partial view showing this first example of the facility in a sixth configuration;

[0045] [ Figure 8 ] is a schematic partial view showing this first example of the facility in a seventh configuration;

[0046] [ Fig. 9 ] is a schematic partial view illustrating the structure and operation of the second embodiment in a first configuration;

[0047] [ Fig.10 ] is a schematic partial view showing this second example of the facility in a second configuration;

[0048] [ Fig.11 ] is a schematic partial view showing this second example of the facility in a third configuration;

[0049] [ Fig.12] is a schematic partial view showing this second example of the facility in a fourth configuration;

[0050] [ Fig.13 ] is a schematic partial view showing details of the structure and operation of another possible embodiment of the facility. DETAILED DESCRIPTION

[0051] The same reference numerals refer to the same elements throughout the drawings.

[0052] In this detailed description, the following embodiments are examples. Although the description relates to one or more embodiments, this does not mean that these features only apply to a single embodiment. Simple features of different embodiments can also be combined and / or interchanged to provide other embodiments.

[0053] [ Figure 1 The hydrogen liquefaction facility 1 shown in ] comprises a hydrogen circuit 2 to be cooled / liquefied. The hydrogen circuit 2 has an upstream end 21 designed to be connected to a gaseous hydrogen source 23 and a downstream end 22 connected to at least one cryogenic storage 8 for liquefied hydrogen produced by the facility 1.

[0054] The gaseous hydrogen source 23 may include an electrolyzer, a gaseous hydrogen network, and / or any other device for generating hydrogen.

[0055] The cryogenic storage 8 comprises, for example, an insulated cryogenic tank under vacuum and is provided with at least one extraction conduit 11 configured to allow liquefied hydrogen to be supplied to at least one tank 19 to be filled (for example, a cryogenic tank 19 transported by a tanker).

[0056] The installation 1 comprises a cold box 18 , ie an insulated, preferably sealed, cryogenic enclosure, which houses at least a part of a cryogenic liquefaction unit forming a liquefier 31 .

[0057] The cold box 18 specifically accommodates a series of heat exchangers 3 , 4 , 5 , 6 for performing heat exchange, and a cold part of the hydrogen circuit 2 for performing heat exchange with these heat exchangers 3 , 4 , 5 , 6 .

[0058] The installation 1 also comprises cooling means for exchanging heat with at least some of the heat exchangers 3 , 4 of the series of heat exchangers, the means being configured to generate cold power for cooling the hydrogen circuit 2 .

[0059] The cooling device preferably comprises a low temperature refrigerator 7, which has a refrigeration cycle for the circulating gas in the working loop. In other words, the working loop makes the circulating gas undergo a thermodynamic cycle, which makes the circulating gas reach the cold end at a low temperature to provide cold cooling power.

[0060] The circulating gas comprises, for example, at least one of the following: hydrogen, helium. The working circuit of the refrigerator 7 comprises a unit 9 for compressing the circulating gas (one or more compressors in series and / or in parallel), units 3, 4 for cooling the circulating gas, a unit 10 for expanding the circulating gas (turbine and / or expansion valve), and units 6, 5, 4, 3 for heating the circulating gas. The units for cooling and heating the gas may comprise heat exchangers, in particular countercurrent heat exchangers, which ensure simultaneous heating and cooling of the circulating gas in the working circuit.

[0061] The installation 1 also comprises at least one pipe 12 for recovering boil-off gas. This recovery pipe 12 is provided with at least one upstream end connected to the reservoir 8 and / or designed to be connected to the tank 19 to be filled, and a downstream end connected to the hydrogen circuit 2, in order to recover boil-off gas, liquefy it and mix it with the liquid hydrogen produced.

[0062] like[ Figure 2 ], the downstream end of the recovery pipe 12 is connected to the hydrogen circuit 2 inside the cold box 18. In addition, before the downstream end of the recovery pipe 12 is connected to the hydrogen circuit 2, the downstream end exchanges heat with at least one exchanger 5, 6 in the series of heat exchangers 3, 4, 5, 6 to cool the downstream end.

[0063] As illustrated, the series of heat exchangers 3, 4, 5, 6 of the cold box preferably comprises 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 pipe 12 to the hydrogen circuit 2 is, for example, located downstream of the first pass of the hydrogen circuit 2 in the final heat exchanger 6 of the series.

[0064] As illustrated, the first passage of the hydrogen circuit 2 in the final heat exchanger 6 preferably comprises a section 29 for hydrogen catalysis configured to perform a conversion of at least a portion of the orthohydrogen into parahydrogen. Downstream of the first passage in the catalytic section 29 of the heat exchanger 6, the hydrogen circuit 2 preferably comprises an expansion unit 30, such as an expansion valve.

[0065] Similarly, the downstream end of the recovery conduit 12 preferably comprises a unit 20 for expanding the boil-off gas stream, between the portion in heat exchange with the exchanger(s) 5 , 6 of the series and the connection with the hydrogen circuit 2 .

[0066] As illustrated, downstream of this connection, the hydrogen circuit 2 receiving the cooled and expanded boil-off gas may have a second passage in the final heat exchanger 6 for supplementary cooling. This second heat exchanger is preferably located in another section of the heat exchanger 6 that does not include the catalytic section.

[0067] As shown, downstream of this second passage in the final heat exchanger 6, the hydrogen circuit 2 may include a unit 23 for expanding the hydrogen stream. This expansion unit 23 is, for example, the final expansion unit in a cold box and comprises, for example, an expansion valve and / or a cryogenic expansion turbine. The fluid thus expanded is liquefied and can then be supplied to a cryogenic storage via appropriate piping.

[0068] This configuration makes it possible to prevent the expansion of the gaseous hydrogen, which would normally cause it to heat up. According to the above configuration, the recovered gaseous hydrogen is expanded in two stages in the liquefier. The first time at the outlet of the final catalytic heat exchanger 6, then during a second passage in the exchanger 6 without catalytic conversion, and finally a final expansion up to the final pressure level designated for the storage 8.

[0069] [ Figure 1 ]and[ Figure 3 ]to[ Figure 8 ] illustrates different configurations or operations that can be implemented by facility 1.

[0070] As shown, the recovery pipe 12 preferably includes a first upstream end connected to the upper end of the reservoir 8 and a second upstream end designed to be connected to the upper end of the onboard storage tank 19. For example, the first upstream end and the second upstream end of the recovery pipe 12 are respectively connected to the downstream end of the recovery pipe via two different pipe branches 121, 122. The two branches 121, 122 can be provided with corresponding valves 221, 222.

[0071] Furthermore, the downstream end 22 of the hydrogen circuit may include two ends connected to the lower and upper parts of the reservoir, respectively, via corresponding valves 201 , 202 , in order to fill the reservoir 8 in its liquid phase or in its gaseous phase.

[0072] In addition, as shown, the extraction pipeline 11 can include an upstream end connected to the reservoir 8 (lower part), which end is preferably 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 to be filled with liquid (at the lower part). The second downstream end of the extraction pipeline 11 can be provided with a valve 113 and can be connected to the second upstream end (branch 122) of the pipeline 12 for recovering gas.

[0073] This fluid connection between the extraction conduit 11 and the branch 122 makes it possible to inject liquid into the tank 19 at its upper part (for example, rain filling).

[0074] In the different configurations shown, closed valves are shown in black and open valves are shown in white.

[0075] exist[ Figure 1 ] configuration, there is no onboard tank to fill.

[0076] The hydrogen of source 23 is liquefied by liquefier 31 and distributed to storage 8 through the pipeline of loop 2. Valve 222 for recovering gas from the onboard tank is closed. Hydrogen can be supplied to the storage at the lower part of the storage. The hydrogen supplied by liquefier 31 can be supercooled to maintain the pressure of storage 8 and withstand its heat input. The pressure of storage 8 can be adjusted by valves 201 and 202, which makes it possible to ensure filling from the bottom and / or from the top. As shown, valve 221 at the first downstream end of the pipeline for recovering boil-off gas from storage 8 can be opened to keep the pipelines 121, 12 cold.

[0077] exist[ Figure 3 ] configuration, the on-board storage tank 19 to be filled is connected to the first downstream end of the extraction pipeline 11. The storage tank 19 is also connected to the second upstream end (branch 122) of the recovery pipeline 12.

[0078] After connecting the tank 19 to the extraction pipe 11 and to the pipe 12 for recovering gas, the pressure in the tank 19 (for example between 3 and 10 bar) can be reduced to a level (for example to a few millibars below P8) lower than the pressure P8 in the reservoir 8. This is done to allow the tank 19 to be filled with liquid from the reservoir by means of a pressure difference (without a pump).

[0079] The hydrogen present in the tank 19 is generally mainly gaseous (1% to 10% in liquid phase) and has a temperature between 100 K and 25 K. A first portion of the recovered hot hydrogen can be sent to the recovery system 32 via a parallel line provided with a valve 322 .

[0080] When the temperature in the tank 19 drops to a determined level (for example between 50 K and 30 K), the gas can be sent to the liquefier (valve 222 opens).

[0081] This gaseous hydrogen will be liquefied in the liquefier 31 as previously described and will be able to flow back to the reservoir 8, provided that the pressure in the tank 19 is higher than the pressure of the reservoir 8 (plus load losses of the circuit).

[0082] To complete the depressurization of the tank 19, it may be necessary to reduce its pressure to below the pressure of the reservoir 8. There are several possibilities. In a first option, the depressurization of the tank 19 can be carried out towards the recovery system 32, see [ Figure 4 ].

[0083] According to another possibility, a pressure equalization can be carried out between the tank 19 and the reservoir 8 (see [ Figure 5 ]: valves 222 and 221 open), followed by pressurization of the reservoir via the liquefier (valve 201 open, see [ Figure 5]). In other words, the gas is delivered from the storage tank 19 to the reservoir via the branch 122 and then 121 of the recovery pipe 12.

[0084] At the end of this first sequence, the pressure P19 of the tank 19 is already lower than the pressure P8 of the storage tank 8 .

[0085] Then, as [ Figure 6 ] As shown, the tank 19 can be filled with liquid. Liquid hydrogen can be delivered from the storage 8 to the upper part of the tank 19 via the extraction pipeline 11 and the branch valve 113 connected to the pipeline for gas recovery.

[0086] The liquid from the storage 8 can be cold enough to maintain the pressure P19 in the storage tank by condensing the vapor in the storage tank 19. The pressure of the storage 8 can be maintained by injecting liquid hydrogen from the liquefier into the gas phase of the storage (filling from the top via the branch 121 of the pipe 12 for recovering gas with the valve 221 open). This hydrogen can come from the hydrogen circuit 2 expanded and heated in the heat exchanger. Therefore, during this stage, the corresponding cold can be recovered inside the liquefier 31 instead of injecting heat into the storage 8 via the pressurization unit ("PBU").

[0087] At the end of this sequence, the pressure P19 of tank 19 may still be close to the pressure P8 of reservoir 8. Tank 19 is filled to more than half of its capacity (e.g. between 85% and 95% of its capacity), but its pressure should preferably be reduced in order to be transportable on the road without losing hydrogen during driving.

[0088] The pressure of the storage tank 19 during transportation may depend on local regulations.

[0089] This decompression can be carried out, for example, via degassing to the recovery system 32 (valve 322 is open). The pressure of the storage tank 19 can reach 1.5 bar, for example. At the same time, the facility can continue to control the pressure of the storage 8, for example by injecting subcooled liquid hydrogen at the top and / or bottom of the storage 8 through the control valves 202 and 201. Reference [ Figure 7 ].

[0090] [ Figure 8 ] shows a variant embodiment, which is different from [ Figure 1 ] is only different in that the branch 122 of the recovery pipe 12 designed to recover the boil-off gas from the storage tank 19 comprises a compression unit 24, such as a low-temperature compressor (cold compressor configured to compress vapors with a temperature between 25K and 100K). As shown, a bypass pipe 124 of the compressor 24 and a series of valves 224, 324 can be provided to ensure that all or part of the flow passes through or does not pass through the compressor 24.

[0091] This compression unit 24 allows better recovery of vapor from the storage tank 19 on the pipeline 12 , in order to return the vapor to the liquefier 31 .

[0092] This compression unit 24 makes it possible to increase the pressure of the recovered hydrogen vapor during the phases of this delivery when the pressure available in the tank 19 is not sufficient to ensure, by pressure difference, the recovery of hydrogen vapor to the storage 8 and / or the liquefier 31, in order to recover these hydrogen vapors to the storage and / or the liquefier. The advantage of the cryogenic compressor 24 compared to conventional compressors at ambient temperature is that its size is reduced due to the greater density of cold hydrogen. The cold temperature of the hydrogen is maintained during compression, and the compressed cold hydrogen can be easily recovered in the storage 8 or to the liquefier 31 in order to be liquefied again.

[0093] [ Figure 8 ] corresponds to the configuration of [ Figure 1 ] configuration. The hydrogen of loop 2 is liquefied by liquefier 31 and distributed in storage 8. The hydrogen can be supercooled in order to control and maintain the pressure in storage 8 and withstand its heat input. The pressure of storage 8 can be adjusted via valves 202, 201 (filling from top / bottom). As shown, valve 221 on the branch for recovering boil-off gas from storage 8 can be opened to keep the line cold. Valves 222, 322 of the branch for recovering boil-off gas from storage tank 19 are closed, and compressor 24 is preferably in a stationary state.

[0094] [ Fig. 9 ] shows a configuration for depressurizing a tank 19 to be filled, which configuration corresponds to [ Figure 3 It should be noted that in the embodiment shown, the extraction pipe 11 is not connected to the upper part of the tank (via the branch 122), but it is understood that the extraction pipe can be connected to the upper part of the tank.

[0095] After connecting the tank to the extraction pipeline 11 and the gas recovery pipeline 12, 122, the pressure of the tank 19 (for example, from 3 bar to 10 bar) can be reduced to a pressure lower than that of the storage 8. The hydrogen present in the tank 19 is in principle mainly gaseous (1% to 10% of the liquid phase) and has a temperature of, for example, between 100K and 25K. The first part of the recovered hot hydrogen can be sent to the recovery system 32 (valve 322 is open). Once the temperature of the gas in the tank 19 drops (for example, between 50K and 30K), the recovered gas can be sent to the liquefier 31 (valves 222, 224 of the pipeline 12 are open). This hydrogen will be liquefied as described above (passage and expansion in the exchanger 6) and will then supply the storage 8, provided that the pressure of the tank 19 remains higher than the pressure in the storage 8 (plus the load losses of the circuit involved). The compressor 24 is preferably not used in this first decompression stage, but can be cooled by the vapor returning to the liquefier 31.

[0096] like[ Fig.10 ], in order to complete the decompression of the storage tank 19, the pressure can be reduced to below the pressure of the storage 8. The compressor 24 can be used to extract vapors from the storage tank 19 and send them to the storage 8. During this stage, the return flow to the liquefier 31 can be closed. The pressure of the storage 8 can still be regulated by valves 202, 201. Therefore, the gas is delivered from the storage tank 19 to the storage 8.

[0097] At the completion of this step, the pressure of the tank 19 is already lower than the pressure of the storage 8. This means that the main part of the tank 19 is filled with liquid. Liquid hydrogen is delivered from the storage 9 to the tank 8 via the extraction pipe 11 (valve 111 is open). The pressure of the storage 8 can be maintained by injecting (valves 201 and / or 202) hydrogen from the liquefier 31. The pressure of the tank 19 can be maintained below the pressure of the storage 8 due to the compressor 24. Reference [ Fig.10 ].

[0098] At the end of this step, the pressure in the tank 19 can still be close to the pressure of the reservoir 8. The filling level of the tank 19 is relatively high (for example between 85% and 95%), but its pressure may need to be reduced in order to be able to be transported on the road and not lose hydrogen during driving. This pressure during transportation may depend on local regulations. The compressor 24 makes it possible to reduce this pressure in the tank 19 to the required starting pressure (without using the valve 332 leading to the recovery system, or by avoiding the loss of hydrogen during driving). The gas in the tank 19 is pumped towards the reservoir 8 (see [ Fig.12 ]).

[0099] The cold compressor 24 may also be used to reduce the pressure of the storage 8 without providing a sub-cooled hydrogen supply. This increases the production capacity of the liquefier.

[0100] [ Fig.13 ] shows a variant embodiment of a circuit for recirculating the recovered boil-off gas in the cold box 18 of the liquefier 31. For simplicity, in [ Fig.13 ] shows only a portion of the cold box 18 and the circuit. Fig.13 ] and [ Figure 2 ] is that the downstream end of the recovery conduit 12 comprises a catalytic section 25 (e.g. a catalytic converter) upstream of the connection with the hydrogen circuit 2, which is configured to perform a conversion of at least a portion of the parahydrogen into orthohydrogen.

[0101] In addition, the recovery conduit 12 includes a bypass portion 26 and a series of valves 27 , 28 configured to ensure that the boil-off gas passes or does not pass through the catalytic section 25 .

[0102] The required specification of the hydrogen liquefier 31 is to provide a minimum conversion of parahydrogen of about 95% at the liquefier outlet. The catalyst present in the final exchanger(s) 5, 6 generally allows a conversion of between 98% and 100%, depending on the hydrogen pressure.

[0103] The gaseous hydrogen flowing back from the tank 19 to be filled is obtained by vaporization of a liquid and generally consists of parahydrogen in a proportion of between 98% and 100%.

[0104] In certain circumstances, facility 1 is not suitable for recovering the superheated hydrogen vapor, as this may interfere with the operation of liquefier 31 .

[0105] These recovered vapors can be cooled by conversion using orthohydrogen into parahydrogen, in contrast to the conversion carried out on the stream in hydrogen circuit 2 in the liquefier.

[0106] Thus, for example, the temperature of these recovered boil-off gases may be between 50 K and 25 K. The higher the temperature, the further the hydrogen is from its equilibrium state at that temperature (20 K for 98% orthohydrogen), and the conversion of parahydrogen to orthohydrogen will cool the hydrogen more.

[0107] The vapour is thus converted from the parahydrogen form to the orthohydrogen form, then liquefied in the heat exchanger 6 / expansion device 20 and then mixed with the hydrogen of the circuit 2 (as previously described) before supplying the storage 8 .

[0108] In principle, this type of catalytic converter 25 is only necessary when the gaseous hydrogen is sufficiently hot (for example when the tank 19 to be filled begins to depressurize) and is under sufficient pressure (pressure is typically between 3 and 10 bar). The bypass system 26, 27, in particular the valve, can be configured to ensure access to the conversion catalyst according to the return temperature of the gas, which can be measured by a temperature sensor 33 in the recovery pipe 12.

[0109] Therefore, when the measured temperature becomes cold enough, or the pressure in the recovery pipe decreases (decompression of the tank 19 is finished), the circuit 28 is closed and the direct supply valve 27 of the exchanger 6 is opened in order to reduce the load losses of the system.

[0110] This control of the pressurization of the tank 19 limits the flow rate in relation to the capacity of the liquefier (making it possible to provide control of the outlet temperature of the exchanger of the reliquefied gas possible).

[0111] It should be understood that this embodiment can be applied to the embodiments and steps described above.

[0112] Furthermore, the above examples are non-limiting. Thus, for example, the facility may include a plurality of reservoirs 8 and / or a plurality of pipes 11 for filling and a plurality of pipes 12 for recovering boil-off gas.

[0113] A cold compressor 24 may be positioned in parallel with the recovery piping for delivering the gas to the liquefier, particularly if multiple storage tanks are being processed simultaneously.

Claims

1. A plant for liquefaction of hydrogen, the plant comprising a hydrogen circuit (2) having an upstream end (21) designed to be connected to a gaseous hydrogen source (23) and a downstream end (22) connected to at least one liquefied hydrogen cryogenic storage (8) of the plant, the cryogenic storage (8) being provided with an extraction pipeline (11) configured to allow the supply of liquefied hydrogen to at least one tank (19), in particular an on-board tank, to be filled, the plant (1) comprising a cold box (18) housing a series of heat exchangers (3, 4, 5, 6) in heat exchange with the hydrogen circuit (2), the plant (1) comprising a cooling device in heat exchange with at least some of the heat exchangers (3, 4) of the series of heat exchangers, the cooling device (11) being in heat exchange with at least one part of the heat exchangers (3, 4) of the series of heat exchangers The device is configured to cool the hydrogen circuit (2), the cooling device comprising a low-temperature refrigerator (7), the low-temperature refrigerator having a refrigeration cycle for a circulating gas in a working circuit, the circulating gas comprising at least one of the following: hydrogen, helium, the working circuit of the refrigerator (7) comprising a unit (9) for compressing the circulating gas, a unit (3, 4) for cooling the circulating gas, a unit (10) for expanding the circulating gas, and a unit (6, 5, 4, 3) for heating the circulating gas, the facility (1) comprising a pipeline (12) for recovering boil-off gas, the pipeline being provided with at least one upstream end connected to the reservoir (8) and / or designed to be connected to a storage tank (19) to be filled, and a pipeline connected to the hydrogen circuit (2) The downstream end of the recovery pipe (12) is connected to the hydrogen circuit (2), wherein the downstream end of the recovery pipe (12) includes a portion for heat exchange with at least one of the series of heat exchangers (3, 4, 5, 6) before the connection with the hydrogen circuit (2), the series of heat exchangers (3, 4, 5, 6) of the cold box (18) including a plurality of heat exchangers positioned in series between the upstream end (21) and the downstream end (22) of the hydrogen circuit (2), the hydrogen circuit (2) having a first passage in the last heat exchanger (6) in the series, the hydrogen circuit (2) including an expansion unit (30), such as an expansion valve, downstream of the first passage, the connection of the downstream end of the recovery pipe (12) to the hydrogen circuit (2) is located The hydrogen circuit (2) is downstream of the first passage in the final heat exchanger (6) in the series and downstream of the expansion unit (30), and downstream of the connection, the hydrogen circuit (2) having received the cooled and expanded boil-off gas has a second passage in the final heat exchanger (6) for supplementary cooling, and downstream of the second passage in the final heat exchanger (6), the hydrogen circuit (2) includes a unit (23) for expanding the hydrogen flow, and the downstream end of the recovery pipe (12) includes a unit (20) for expanding the boil-off gas flow located between the portion for heat exchange with at least one heat exchanger (5, 6) in the series of heat exchangers (3, 4, 5, 6) and the connection with the hydrogen circuit (2).

2. The facility according to claim 1, characterized in that The first passage of the hydrogen circuit (2) in the final heat exchanger (6) of the series comprises a section (29) for catalytic hydrogenation configured to carry out the conversion of at least a portion of the orthohydrogen into parahydrogen.

3. The facility according to claim 1 or 2, characterized in that The second passage into the final heat exchanger (6) does not include a section for catalyzing orthohydrogen into parahydrogen.

4. The facility according to any one of claims 1 to 3, characterized in that Said unit (23) for expanding the hydrogen circuit (2), located downstream of the second passage in the final heat exchanger (6), comprises at least one of the following: an expansion valve, a turbine.

5. The facility according to any one of claims 1 to 4, characterized in that Upstream of the connection with the hydrogen circuit (2), the downstream end of the recovery conduit (12) comprises a catalytic section (25) configured to perform a conversion of at least part of the parahydrogen into orthohydrogen.

6. The facility according to claim 5, characterized in that The downstream end of the recovery conduit (12) includes a bypass portion (26) and a series of valves (27, 28) configured to ensure that the boil-off gas flows through or does not flow through the catalytic section (25).

7. The facility according to any one of claims 1 to 6, characterized in that The recovery line (12) comprises a compression unit (24), such as a low-temperature compressor.

8. The facility according to any one of claims 1 to 7, characterized in that The recovery pipe (12) comprises a first upstream end connected to the reservoir (8) and a second upstream end designed to be connected to an on-board storage tank (19).

9. Installation according to claims 7 and 8, characterized in that The first upstream end and the second upstream end of the recovery pipe (12) are respectively connected to the downstream end of the recovery pipe (12) via two different pipe branches, and is characterized in that the compression unit (24) is located in the pipe branch of the second upstream end of the recovery pipe (12).

10. A method for liquefying hydrogen using the facility according to any one of claims 1 to 9, comprising the steps of recovering boil-off gas via the recovery pipe (12), cooling the recovered boil-off gas in the cold box (18), expanding the boil-off gas in the cold box (18), and mixing the expanded boil-off gas with a hydrogen stream to be cooled.

11. The method for liquefying hydrogen according to claim 10, comprising at least one of the following: a step of expanding the mixture of the boil-off gas and the hydrogen stream to be cooled, a step of expanding the mixture of the boil-off gas and the hydrogen stream to be cooled.

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