Apparatus and method for producing liquefied hydrogen
By setting up a buffer storage in the liquefied hydrogen production plant and dynamically adjusting the cooling power of the liquefier, the problem of liquefier control under intermittent energy is solved, and efficient liquefied hydrogen production and cost optimization are achieved.
Patent Information
- Application Number
- CN202510363661.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-03-27
- Filing Date
- 2025-03-26
- Publication Date
- 2025-09-30
AI Technical Summary
Existing liquefied hydrogen production plants find it difficult to effectively control the cooling power and liquefaction capacity of the liquefier under intermittent energy supply, resulting in insufficient production capacity and increased costs.
By setting up a buffer storage between the hydrogen generator and the liquefier, and using pressure sensors and programmable electronic mechanisms to dynamically adjust the filling level of the buffer storage, the cooling power and liquefaction capacity of the liquefier can be flexibly changed, thereby achieving efficient control of the liquefier.
It effectively responds to fluctuations in intermittent energy supply, improves the flexibility and production efficiency of liquefied hydrogen production, and reduces production costs.
Smart Images
Figure CN120719307A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an apparatus and a method for producing liquefied hydrogen.
[0002] More particularly, the present invention relates to an apparatus for producing liquefied hydrogen, the apparatus comprising: a hydrogen generator, such as an electrolyzer, configured to produce hydrogen; a liquefier; a feed line connecting a hydrogen outlet of the hydrogen generator to an inlet of the liquefier, the liquefier comprising a refrigerator having a circulation loop configured to supply cooling power and cool hydrogen from the feed line to liquefy the hydrogen, the apparatus comprising a buffer storage configured to store compressed hydrogen between the hydrogen generator and the liquefier / the apparatus comprising a buffer storage configured to store compressed hydrogen located between the hydrogen generator and the liquefied hydrogen. Background Art
[0003] For example, the present invention relates to the production of hydrogen using electrolyzers powered by renewable energy. Such plants can be connected downstream to a gas grid, a liquefier, or an ammonia or methanol production unit. These plants must be controlled according to the generation capacity of renewable energy sources. This control can, in particular, reduce investments in buffer storage or additional equipment required to manage intermittent power supply. It can also increase production capacity by avoiding losses and reduce production costs by limiting grid usage.
[0004] The ability of a liquefier to change its operating point (or "operating speed") is relatively limited. That is, the cooling power and / or liquefaction capacity of the liquefier is difficult to change.
[0005] Therefore, one solution for dealing with fluctuations in the intermittent energy source (and therefore in the production of hydrogen to be liquefied) consists in providing a buffer storage of hydrogen to feed the feed circuit of the liquefier.
[0006] These buffer stores can be arranged in series between the electrolyser and the liquefier and / or connected in parallel with the liquefier at the outlet of the electrolyser.
[0007] The control schemes for these plants were unsatisfactory. Summary of the Invention
[0008] It is an object of the present invention to overcome all or some of the above-mentioned disadvantages of the prior art.
[0009] For this purpose, an apparatus according to the invention which otherwise corresponds to the general definition given in the introduction is essentially characterized in that the liquefier is configured to provide a cooling power and / or a liquefaction capacity which can be varied between at least two levels, the apparatus comprises a determination device for determining a filling level of the buffer storage, the apparatus being configured to vary the cooling power and / or the liquefaction capacity of the liquefier as a function of the filling level of the buffer storage determined by the determination device.
[0010] Additionally, embodiments of the present invention may include one or more of the following features:
[0011] - the determination means for determining the filling level of the buffer store is configured to determine the filling level of the buffer store from a plurality of predetermined filling levels, the device being configured to establish the cooling power and / or the liquefaction capacity of the liquefier at specific levels respectively corresponding to the predetermined filling levels of the buffer store;
[0012] The device is designed to reduce the cooling power and / or the liquefaction capacity of the liquefier in a correlated / relative manner when the filling level of the buffer store decreases;
[0013] the device is configured to correlatively increase the cooling power and / or the liquefaction capacity of the liquefier as the filling level of the buffer store increases;
[0014] the device is designed to change the cooling power and / or the liquefaction capacity of the liquefier after a given delay, in dependence on the filling level of the buffer store determined by the determination means, the given delay being in the range of one hour to ten hours;
[0015] - the determination means for determining the fill level of the buffer store comprises a pressure sensor;
[0016] a pressure sensor configured to measure the pressure in the buffer storage and / or in a line connected to an outlet of the buffer storage;
[0017] the liquefier comprises a refrigerator having a circulation circuit in which a circulating gas flow undergoes a given thermodynamic cycle, the device being configured to vary the cooling power and / or liquefaction capacity of the liquefier by varying the flow rate / flow velocity and / or the amount of circulating gas in the circulation circuit;
[0018] - the apparatus is configured to reduce the cooling power and / or liquefaction capacity of the liquefier by reducing the flow rate / flow velocity and / or amount of the circulating gas in the circulating loop via at least one of: a circulating gas discharge line leading to the feed line; a circulating gas discharge line leading to the discharge zone; means for liquefying at least a portion of the circulating gas in the circulating loop;
[0019] the liquefier comprises a refrigerator having a circulation circuit in which a circulating gas stream undergoes a given thermodynamic cycle comprising compression and expansion / the circulating gas stream undergoes a given thermodynamic cycle in the circulation circuit, the circulation circuit comprising a compression device and an expansion device, the device being configured to vary the cooling power and / or liquefaction capacity of the liquefier by varying the compression of the circulating gas in the circulation circuit / the pressure level of the compression device;
[0020] The liquefier comprises a plurality of independent refrigerators having circulation circuits, each refrigerator being configured to provide a corresponding cooling power for cooling hydrogen gas from a feed pipeline so as to liquefy the hydrogen gas, and the apparatus being configured to vary the cooling power and / or liquefaction capacity of the liquefier by varying the cooling power and / or liquefaction capacity of each refrigerator differently;
[0021] the determination means for determining the filling level of the buffer store comprises programmable electronic means for storing and processing data, the programmable electronic means comprising a microprocessor, the determination means for determining the filling level being configured to receive operating data from the hydrogen generator and / or consumption data of the liquid hydrogen produced by the liquefier and to use these data to predict a future filling level of the buffer store within a future time interval, for example within a range from 1 hour to 24 hours, the device being configured to vary the cooling power and / or the liquefaction capacity of the liquefier as a function of the future filling level of the buffer store determined by the determination means;
[0022] The hydrogen generator comprises an intermittent power supply supplied by a renewable energy source, such as solar energy, and the determination means for determining the filling level are configured to receive weather forecast data and to predict a future filling level of the buffer storage based on the weather forecast data.
[0023] The present invention also relates to a method for producing liquefied hydrogen using a device according to any of the above or following features, the method comprising the steps of: determining the filling level of a buffer store; and adjusting the cooling power and / or the liquefaction capacity of a liquefier as a function of the determined filling level of the buffer store.
[0024] According to other possible specific characteristics:
[0025] - determination of the filling level of the buffer store, for example by means of pressure measurement, and / or estimation and / or prediction based on operating data from the installation, including: the hydrogen production capacity of each hydrogen generator; the historical hydrogen production capacity of each hydrogen generator; meteorological data; current and future consumption of liquid hydrogen produced by the liquefier;
[0026] the step of adjusting the cooling power and / or the liquefaction capacity of the liquefier comprises a change in the cooling power and / or the liquefaction capacity of the liquefier performed in response to a change in the filling level of the buffer store, the change in the cooling power and / or the liquefaction capacity being performed concomitantly with a change in the determined filling level of the buffer store and / or before and / or after the change in the determined filling level of the buffer store;
[0027] - the liquefier comprises a refrigerator having a circulation loop in which a circulation gas flow undergoes a given thermodynamic cycle, the step of adjusting the cooling power and / or the liquefaction capacity of the liquefier comprising at least one of the following: changing the flow rate and / or the amount of the circulation gas in the circulation loop, for example by discharging the circulation gas from the circulation loop; reducing the amount of gas in the circulation loop by partially liquefying the circulation gas in a separator vessel; changing the pressure of a compression / compression device of the circulation gas in the circulation loop;
[0028] The method comprises a step of stopping the plant, in which the liquefier is stopped, followed by a step of restarting the plant and the liquefier, the method comprising a given delay after the restart and before the step of adjusting the cooling power and / or liquefaction capacity of the liquefier, and / or comprising a delay until the filling level of the buffer store reaches a predetermined threshold, the given delay being, for example, in the range of 2 to 12 hours.
[0029] The invention may also relate to any alternative device or method comprising any combination of the above or below features falling within the scope of the claims. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Further distinguishing features and advantages will become apparent from reading the following description with reference to the accompanying drawings.
[0031] The invention will be better understood from a reading of the following description, given by way of example only and with reference to the accompanying drawings, in which:
[0032] Figure 1 is a schematic partial view showing the structure and operation of a first exemplary embodiment according to the present invention;
[0033] Figure 2 is a schematic partial view showing the structure and operation of a second exemplary embodiment according to the present invention. DETAILED DESCRIPTION
[0034] Throughout the drawings, the same reference numerals refer to the same elements.
[0035] In this detailed description, the following embodiments are examples. Although the description relates to one or more embodiments, it does not mean that these features only apply to a single embodiment. The individual features of different embodiments may also be combined and / or interchanged to provide other embodiments.
[0036] Figure 1 The apparatus 1 for producing liquefied hydrogen shown in FIG. 1 includes a hydrogen generator 2 , such as an electrolyzer, configured to produce hydrogen; a liquefier 7 ; and a feed line 6 connecting a hydrogen outlet of the hydrogen generator 2 to an inlet of the liquefier 7 .
[0037] The apparatus 1 comprises a buffer store 9 which is configured to store compressed hydrogen between the hydrogen generator 2 and the liquefier 7. In this example, the buffer store 9 is arranged in series between the hydrogen generator 2 and the liquefier 7.
[0038] As shown in the figure, the apparatus 1 may include at least one compressor 10 for compressing the hydrogen generated by the hydrogen generator 2 to fill the buffer storage 9 .
[0039] The liquefier 7 includes a refrigerator 8 having a circulation loop 18 configured to supply cooling power and cool the hydrogen from the feed line 6 to liquefy it.
[0040] The liquefier 7 is configured to provide a cooling power and / or liquefaction capacity that can be varied between at least two different levels (N1, N2).
[0041] The device 1 comprises a determination device 3 for determining the fill level of the buffer storage 9 , and the device 1 is designed to change the cooling power and / or liquefaction capacity of the liquefier 7 as a function of the fill level of the buffer storage 9 determined by the determination device 3 .
[0042] For example, the determination mechanism 3 for determining the filling level of the buffer storage 9 is configured to determine the filling level of the buffer storage 9 from a plurality of predetermined filling levels, and the device 1 is configured to establish the cooling power and / or liquefaction capacity of the liquefier 7 at a plurality of specific levels corresponding to the plurality of predetermined filling levels of the buffer storage 9, respectively.
[0043] The determination means 3 for determining the fill level of the buffer storage 9 can, for example, comprise a pressure sensor which measures the pressure in the buffer storage 9 .
[0044] The pressure sensor 3 is configured, for example, to measure the pressure in the buffer storage 9 and / or the pressure in a line connected to an outlet of the buffer storage 9 .
[0045] The fill level can be determined based on the measured pressure value.
[0046] For example, a fill level of 0% may be set for a minimum pressure upstream of the inlet valve of the liquefier (eg 20 to 40 bar).
[0047] A fill level of 100% may be set for a maximum pressure upstream of the inlet valve of the liquefier (eg 40 bar to 100 bar).
[0048] Thus, for example, the device can be configured to relatively reduce the cooling power and / or the liquefaction capacity of the liquefier 7 when the filling level of the buffer store 9 decreases.
[0049] Similarly, the apparatus may be configured to relatively increase the cooling power and / or the liquefaction capacity of the liquefier 7 as the filling level of the buffer storage 9 increases.
[0050] Thus, the operating rate of the liquefier 7 can be set according to the filling level of the buffer storage 9 (e.g., the filling level measured by its pressure), without the setting of the action level depending on the actual production characteristics of the liquefier 7. For example, all or some of the following configurations are possible, e.g., with the following actions on the liquefier:
[0051] If the fill level of one or more buffer stores 9 is 70% or higher, the operating rate of the liquefier 7 can be set to 100%.
[0052] If the filling level of one or more buffer stores 9 is 50% or higher, the operating rate of the liquefier 7 can be set to 75%.
[0053] If the fill level of the buffer store(s) 9 is 35% or higher, the operating rate of the liquefier 7 can be set to 50%.
[0054] If the fill level of one or more buffer stores 9 is 10% or higher, the operating rate of the liquefier 7 can be set to 25%.
[0055] If the fill level of one or more buffer stores 9 is 2% or less, the operating rate of the liquefier 7 can be set to 0%.
[0056] The apparatus may be configured to limit the frequency or number of changes in the liquefier operating rate, for example to avoid cycling around an operating point.
[0057] For example, the device can be designed such that the cooling power and / or the liquefaction capacity of the liquefier 7 can be changed only after a given delay (after a change in the fill level of the buffer store 9 ), for example after one to ten hours.
[0058] For example, a minimum delay of six hours may be provided between two changes.
[0059] Similarly, if the plant 1 is started up (starting and cooling down the liquefier 7 ), such a start-up is only possible after a delay of 6 hours and if the filling level of the buffer store 9 is greater than or equal to a threshold value, for example 50%.
[0060] The liquefier 7 includes, for example, at least one refrigerator 8 having a circulation loop 18 in which a circulating gas stream undergoes a given thermodynamic cycle including expansion. The apparatus 1 can be configured to vary the cooling power and / or liquefaction capacity of the liquefier 7 by varying, for example, the flow rate and / or amount of the circulating gas in the circulation loop 18.
[0061] For example, the apparatus may be configured to reduce the cooling power and / or liquefaction capacity of the liquefier 7 by reducing the flow rate and / or amount of the circulating gas in the circulating loop 18. This may be achieved, for example, by at least one of the following: a circulating gas discharge line leading to the feed line 6, a circulating gas discharge line leading to a discharge zone, and a mechanism for liquefying at least a portion of the circulating gas in the circulating loop 18.
[0062] In the case where the liquefier 7 comprises a refrigerator 8 having a circulation circuit 18 comprising a compression device 80 and an expansion device in which the circulating gas flow undergoes a given thermodynamic cycle, the device can be configured to vary the cooling power and / or liquefaction capacity of the liquefier 7 by varying the pressure level of the compression / compression device 80 of the circulating gas in the circulation circuit 18.
[0063] Similarly, the liquefier 7 may include multiple independent refrigerators 8 having circulation loops 18 (i.e., multiple "units" connected in parallel), each refrigerator being configured to provide a corresponding cooling power for cooling the hydrogen from the feed line 6 in order to liquefy it. In this case, the apparatus 1 may be configured to vary the cooling power and / or liquefaction capacity of the liquefier 7 by differentially varying the cooling power and / or liquefaction capacity of each refrigerator 8.
[0064] Thus, for example, in the case of a liquefier having a plurality of chiller units connected in parallel (e.g. three units), the apparatus may be configured to vary the control of the operating rate of one or more units, for example by reducing the power to 25% if the fill level of the buffer storage falls below 20%.
[0065] To reduce the operating rate, the plant 1 can, for example, be designed to shut down the units gradually and sequentially in order to maintain the liquefaction capacity.
[0066] For example, if the filling level of the buffer store 9 falls below a first threshold value (eg 15%), the operating rate of the units (eg three units) can each be set to 25% of their maximum cooling power.
[0067] Similarly, if the filling level of the buffer store 9 falls below a second threshold value (eg 10%), one unit may be stopped and the operating rate of the other units (eg two) may each be set to 25% of their maximum cooling power.
[0068] Similarly, if the filling level of the buffer store 9 falls below a third threshold value (eg 2%), the second unit can be stopped and the operating rate of the remaining units can be set to 25% of their maximum cooling power.
[0069] A gradual restart of the plant can be performed in reverse by gradually starting the liquefaction units.
[0070] Figure 2 A variant is shown in which a buffer store 9 is connected in parallel with the liquefier 7 .
[0071] For example, a fill level of 0% can be set for a minimum pressure in the buffer store 9 (eg 20 bar to 40 bar).
[0072] A fill level of 100% can be set for a maximum pressure in the buffer store 9 (e.g. 40 to 250 bar). Operating situations can be predefined (e.g. 50%, 75%, 100% fill levels or operating rates). This allows the control values of the device 1 to be automatically changed to ensure efficient operation.
[0073] For example, the reduction in cooling power (operating rate) produced by the liquefier can be controlled by the following measures, preferably taken individually or in combination or sequentially in this order:
[0074] - reducing the circulating gas flow in the cycle of one or more refrigerators;
[0075] - Reducing the amount of circulating fluid in the circulation loop to reduce the high pressure in the circulation loop (while maintaining the low pressure after expansion).
[0076] For example, in the case where the cycle gas consists of or comprises hydrogen, a portion of this cycle gas can be diverted into the feed loop 6 .
[0077] In the case where the circulating gas consists of nitrogen or contains nitrogen (nitrogen circulating refrigerator), part of the circulating gas can be discharged to the outside (for example to ventilation).
[0078] In case of changing the pressure within a refrigerator cycle, for example in the case of a nitrogen cycle and / or a hydrogen cycle, the corresponding refrigerator can be controlled to change at least one pressure value in the cycle (relatively low, medium or high).
[0079] For example, the determination means for determining the fill level of the buffer memory 9 may comprise a programmable electronic data storage and processing means 4 comprising a microprocessor.
[0080] Similarly, control (changing) of the operating rate of the refrigerator 8 as described above may be performed by the programmable electronic data storage and processing mechanism 4 (and / or another mechanism of the same type).
[0081] For example, such electronic means may implement the actions described above for controlling the device 1 .
[0082] The filling level determination device 3 may be configured to receive operating data from the hydrogen generator 2 and / or data on the consumption of liquid hydrogen produced by the liquefier 7 and use this data to predict a future filling level of the buffer storage 9 within a future time interval, for example, in the range of 1 to 24 hours. The device 1 may be configured to vary the cooling power and / or liquefaction capacity of the liquefier 7 as a function of the future filling level of the buffer storage 9 determined by the determination device 3.
[0083] According to this forecasting method, the operating rate of the liquefier 7 can be set according to the filling level of the buffer storage 9 in a given future, for example, within 12 hours. The filling state of the buffer storage 9 can be calculated based on the hydrogen production of the electrolyzer in the next 12 hours, for example by estimating the future production using various parameters (such as weather or any other forecast and / or historical methods).
[0084] The amount of hydrogen available can be calculated from the available electricity and the efficiency of the electrolyser and the compression of the hydrogen produced by the electrolyser.
[0085] Similarly, the hydrogen consumption of downstream user units can be estimated. For example, the amount of liquefied hydrogen consumed (and / or used to produce ammonia or methanol) can be calculated based on the current load level.
[0086] The device 1 can be controlled, for example, in the following manner.
[0087] If the filling level of the buffer storage 9 in a predetermined future (e.g. 12 hours) is greater than a maximum threshold (e.g. 100% or more), the cooling power and / or liquefaction capacity of the liquefier 7 is increased (preemptively increased). New predictions / simulations can be performed with these new operating conditions.
[0088] On the other hand, if the filling level of the buffer storage 9 is less than a minimum threshold value (e.g. 0%) in the predetermined future (e.g. 12 hours), the cooling power and / or liquefaction capacity of the liquefier 7 is reduced (pre-reduced). A new prediction / simulation can be performed with these new operating conditions.
[0089] In other cases, the filling level of the buffer storage 9 in a predetermined future (eg 12 hours) is within an acceptable range (eg 5-80%), and the cooling power and / or liquefaction capacity of the current liquefier 7 does not change.
[0090] Different cooling power values and / or liquefaction capacity values may be predetermined, for example 25%, 50%, 75% and 100%, for the liquefier 7. The use of such predetermined load levels allows for quick and efficient changes in operating rate.
[0091] Similarly, a minimum stopping time of the apparatus 1 may be provided to avoid stopping / restarting and limit the impact on critical equipment.
[0092] For example, in particular after a liquefier shutdown, a given delay of, for example, 24 hours may be provided before a new restart.
[0093] Furthermore, such a restart may be subject to at least one basic prerequisite, such as a minimum downtime (eg 6 hours) and a sufficient fill level of the buffer store 9 (eg at least 25% for a future duration, such as 12 hours).
[0094] The following condition can also be provided: the future hydrogen production of source 2 is at least a part (e.g. 50%) of the hydrogen amount required for operating the device 1 (e.g. the cooling power and / or liquefaction capacity of the liquefier 7 is at a certain level, e.g. 25% for a given future time period, e.g. 16 hours or 6 hours).
[0095] The plant 1 can also be operated in a hybrid or mixed mode. That is, the forecast of hydrogen production can be used to control the plant (the operating rate of the liquefier), but if necessary, the operating parameters are reassessed and changed based on the actual filling data from the buffer storage 9. This helps to limit downtime.
[0096] For example, a six-hour hydrogen production forecast can be made to calculate the available hydrogen and add it to the stated amount.A backup reserve (eg 10% of the maximum fill level) can be subtracted from the available amount in the buffer store 9 .
[0097] The average value of the amount of hydrogen available determines the new operating rate of the liquefier (eg 25%, 50%, 75%, 100%). Preferably, the change in operating rate is made after a delay (eg 6 hours).
[0098] The present invention allows for efficient adaptation of the plant to handle fluctuations in intermittent energy sources (and thus the production of hydrogen to be liquefied).
[0099] Preferably, high-load operation of the liquefier (close to maximum power) is only permitted when the filling level of the buffer store 9 is sufficient (eg at least 90%).
[0100] Starting from high or maximum power, if the fill level of the buffer store 9 drops below a certain level (e.g. 50%), the operating rate of the liquefier may be reduced (e.g. to 75%) until the fill level is restored (e.g. above 95%).
[0101] If the plant 1 is operated at a reduced load (eg minimum load) and the filling level is below the level required to ensure a certain hydrogen supply time (eg one hour), the plant can be stopped.
[0102] For example, restart can only be achieved if the following conditions are met: the fill level is sufficient to operate at a given operating rate (e.g., a minimum operating rate or a reduced operating rate) for a given period of time (e.g., 12 hours), and the predicted amount of hydrogen produced by source 2 in the future (e.g., the next 6 hours) is greater than the amount required to operate at the reduced operating rate (e.g., greater than 50%).
[0103] Running the example may include the following steps:
[0104] - estimating hydrogen production over the next few hours (e.g., 12 hours), which may be based on meteorological data and the current or historical state of electricity generation from one or more renewable energy sources;
[0105] - Measuring or calculating the fill level of the buffer store 9 .
Claims
1. An apparatus for producing liquefied hydrogen, comprising: A hydrogen generator (2) configured to produce hydrogen, such as an electrolyzer; a liquefier (7); a feed line (6) connecting the hydrogen outlet of the hydrogen generator (2) to the inlet of the liquefier (7), the liquefier (7) comprising a refrigerator (8) having a circulation loop (18), the circulation loop being configured to supply cooling power and cool the hydrogen from the feed line (6) to liquefy the hydrogen, the apparatus (1) comprising a buffer storage (9) configured to store compressed hydrogen between the hydrogen generator (2) and the liquefier (7), the liquefier (7) being configured to provide a hydrogen storage system capable of being cooled at at least two levels (N1, N2) The device (1) comprises a determining mechanism (3) for determining the filling level of the buffer storage (9), and the device (1) is configured to change the cooling power and / or liquefaction capacity of the liquefier (7) according to the filling level of the buffer storage (9) determined by the determining mechanism (3). The device is characterized in that the device is configured to change the cooling power and / or liquefaction capacity of the liquefier (7) according to the filling level of the buffer storage (9) determined by the determining mechanism (3) after a given delay, and the given delay is, for example, in the range of 1 hour to 10 hours.
2. The device according to claim 1, characterized in that The determining means (3) for determining the filling level of the buffer storage (9) is configured to determine the filling level of the buffer storage (9) from a plurality of predetermined filling levels, and the device (1) is configured to establish the cooling power and / or liquefaction capacity of the liquefier (7) at specific levels respectively corresponding to the predetermined filling levels of the buffer storage (9).
3. The device according to claim 1 or 2, characterized in that The device (1) is designed to relatively reduce the cooling power and / or liquefaction capacity of the liquefier (7) when the filling level of the buffer store (9) decreases.
4. The device according to any one of the preceding claims, characterized in that The device (1) is configured to relatively increase the cooling power and / or liquefaction capacity of the liquefier (7) when the filling level of the buffer store (9) increases.
5. The device according to any one of the preceding claims, characterized in that The determining means (3) for determining the filling level of the buffer store (9) comprises a pressure sensor.
6. The device according to claim 5, characterized in that The pressure sensor (3) is configured to measure the pressure in the buffer storage (9) and / or the pressure in a pipeline connected to an outlet of the buffer storage (9).
7. The device according to any one of the preceding claims, characterized in that The liquefier (7) comprises a refrigerator (8) having a circulation loop (18) in which a circulating gas flow undergoes a given thermodynamic cycle, and the device (1) is configured to change the cooling power and / or liquefaction capacity of the liquefier (7) by changing the flow rate and / or amount of the circulating gas in the circulation loop (18).
8. The device according to claim 7, characterized in that The apparatus is configured to reduce the cooling power and / or liquefaction capacity of the liquefier (7) by reducing the flow rate and / or amount of circulating gas in the circulating loop (18) via at least one of: a circulating gas discharge line leading to the feed line (6); a circulating gas discharge line leading to a discharge zone; a mechanism for liquefying at least a portion of the circulating gas in the circulating loop (18).
9. The device according to any one of the preceding claims, characterized in that The liquefier (7) comprises a refrigerator (8) having a circulation loop (18) in which a circulating gas flow undergoes a given thermodynamic cycle, the circulating loop comprising a compression device (80) and an expansion device, the device (1) being configured to change the cooling power and / or liquefaction capacity of the liquefier (7) by changing the pressure level of the compression device (80) of the circulating gas in the circulation loop (18).
10. The device according to any one of the preceding claims, characterized in that The liquefier includes a plurality of independent refrigerators (8) having a circulation loop (18), each refrigerator being configured to supply a corresponding cooling power for cooling the hydrogen from the feed line (6) so as to liquefy the hydrogen, and the device (1) is configured to change the cooling power and / or liquefaction capacity of the liquefier (7) by differentially changing the cooling power and / or liquefaction capacity of each refrigerator (8).
11. The device according to any one of the preceding claims, characterized in that The determining means (3) for determining the filling level of the buffer storage (9) comprises a programmable electronic means (4) for storing and processing data, the programmable electronic means comprising a microprocessor, the determining means (3) for determining the filling level being configured to: receive operating data from the hydrogen generator (2) and / or consumption data of the liquid hydrogen produced by the liquefier (7); and use the operating data and / or consumption data to predict a future filling level of the buffer storage (9) within a future time interval, the future time interval being, for example, in the range of 1 hour to 24 hours, the device (1) being configured to change the cooling power and / or liquefaction capacity of the liquefier (7) in accordance with the future filling level of the buffer storage (9) determined by the determining means (3).
12. The device according to claim 11, characterized in that The hydrogen generator (2) comprises an intermittent power supply supplied by renewable energy sources such as solar energy, and the determination means (3) for determining the filling level is configured to receive weather forecast data and to predict the future filling level of the buffer storage (9) based on the weather forecast data.
13. A method for producing liquefied hydrogen using the apparatus according to any one of the preceding claims, the method comprising the steps of: - determining the filling level of the buffer store (9); - adjusting the cooling power and / or liquefaction capacity of the liquefier (7) as a function of the determined filling level of the buffer store (9).
14. The method according to claim 13, characterized in that The filling level of the buffer store (9) is determined as follows: for example by means of a pressure measurement and / or by estimation and / or prediction based on operating data from the device, the operating data of the device comprising: the hydrogen production capacity of each hydrogen generator (2); the historical hydrogen production capacity of each hydrogen generator (2); meteorological data; the current consumption and future consumption of liquid hydrogen produced by the liquefier (7).
15. The method according to claim 13 or 14, characterized in that The step of adjusting the cooling power and / or liquefaction capacity of the liquefier (7) comprises a change in the cooling power and / or liquefaction capacity of the liquefier (7) performed in response to a change in the filling level of the buffer storage (9), the change in the cooling power and / or liquefaction capacity being performed along with a determined change in the filling level of the buffer storage (9) and / or being performed before and / or after a determined change in the filling level of the buffer storage (9).
16. The method according to any one of claims 13 to 15, characterized in that The liquefier (7) comprises a refrigerator (8) having a circulation loop (18) in which a circulating gas flow undergoes a given thermodynamic cycle, and the step of adjusting the cooling power and / or liquefaction capacity of the liquefier (7) comprises at least one of the following: changing the flow rate and / or amount of the circulating gas in the circulation loop (18), for example, discharging the circulating gas from the circulation loop (18); reducing the amount of gas in the circulation loop (18) by partially liquefying the circulating gas in a separator container; changing the pressure of the compression device (80) of the circulating gas in the circulation loop (18).
17. The method according to claim 13 , comprising a step of stopping the plant, in which the liquefier ( 7 ) is stopped, followed by a step of restarting the plant ( 1 ) and the liquefier ( 7 ), the method comprising a given delay after the restart and before the step of adjusting the cooling power and / or the liquefaction capacity of the liquefier ( 7 ), and / or comprising a delay until the filling level of the buffer store ( 9 ) reaches a predetermined threshold value, the given delay being, for example, in the range of 2 hours to 12 hours.