Apparatus and method for liquefying fluids such as hydrogen and / or helium

Abstract

A device for liquefying a fluid is disclosed, the device comprising a circuit (3) for a fluid to be cooled, the device (1) comprising a set of one or more heat exchangers (6, 7, 8, 9, 10, 11, 12, 13) exchanging heat with the circuit (3) for the fluid to be cooled, at least one first cooling system (20) exchanging heat with at least some of the set of one or more heat exchangers (6, 7, 8, 9, 10, 11, 12, 13), the first cooling system (20) being a refrigerator having a refrigeration cycle with a circulating gas comprising mainly helium, the refrigerator (20) comprising the following components arranged in series in a circulation loop (14): a circulating gas compression mechanism (15), at least one circulating gas cooling member (16, 5, 6, 8, 10, 12), a mechanism for expanding the circulating gas (17) and at least one expanded circulating gas heating member (13, 12, 11, 10, 9, 8, 7, 6, 5), wherein the compression mechanism comprises at least four compression stages (15) in series consisting of a set of one or more centrifugal type compressors (15) mounted on a shaft (19, 190) rotated by a set of one or more electric motors (18), the expansion mechanism comprises at least three expansion stages in series consisting of a set of radial turbines (17), the at least one circulating gas cooling member (16, 5, 6, 8, 10, 12) is configured to cool the circulating gas at the outlet of at least one of the turbines (17), and wherein at least one of the turbines (17) is coupled to the same shaft (19) as at least one compression stage (15) so as to supply mechanical work produced during expansion to the compression stage (15).

Description

[0001] The present invention relates to a device and a method for liquefying a fluid such as hydrogen and / or helium.

[0002] The present invention more particularly relates to a device for refrigerating and / or liquefying a fluid such as hydrogen and / or helium, the device comprising a circuit for the fluid to be cooled, the circuit having an upstream end intended to be connected to a source of fluid and a downstream end intended to be connected to a means for collecting the fluid, the device comprising a set of one or more heat exchangers in heat exchange with the circuit for the fluid to be cooled, the device comprising at least one first cooling system in heat exchange with at least part of the set of one or more heat exchangers, the first cooling system being a refrigerator carrying out a refrigeration cycle of a circulating gas, said refrigerator comprising, arranged in series in a circulation loop: a mechanism for compressing the circulating gas, at least one means for cooling the circulating gas, a mechanism for expanding the circulating gas and at least one means for heating the expanded circulating gas, wherein the compression mechanism comprises a plurality of compression stages in series consisting of a set of centrifugal impeller type compression mechanisms mounted on shafts driven in rotation by a set of electric motors, the expansion mechanism comprises at least one expansion stage consisting of a set of radial turbines having a determined working pressure at the inlet, and wherein at least one of the turbines or respectively the turbines is / are coupled to the same shaft as at least one compression stage in order to supply the mechanical work produced during expansion to the compression stage.

[0003] The solutions of the prior art for liquefying hydrogen (H2) combine a cycle compressor which obtains a relatively low isothermal efficiency (about 60% to 65%) and has a relatively limited volumetric capacity, but which is rather high in investment costs and high in maintenance costs.

[0004] Document EP 3368630 A1 describes a known method for liquefying hydrogen.

[0005] The aim of the present invention is to overcome all or some of the drawbacks of the prior art described above.

[0006] To this end, the essential characteristics of the device according to the invention, which also complies with the general definition given in the above preamble in other respects, consist in that the at least one turbine coupled and the corresponding compression stage are structurally configured so that the pressure of the circulating gas leaving the turbine differs by no more than 40% and preferably no more than 30% or no more than 20% from the pressure of the circulating gas at the inlet of the compression stage, and / or the at least one turbine coupled and the corresponding compression stage are structurally configured so that the pressure of the circulating gas entering the turbine differs by no more than 40% and preferably no more than 30% or no more than 20% from the pressure of the circulating gas at the outlet of the compression stage.

[0007] Furthermore, embodiments of the application can include one or more of the following features:

[0008] - the expansion mechanism comprises at least two expansion stages in series consisting of a set of radial turbines in series, and in that, in the circulation direction of the circulating gas, the at least two turbines in series are respectively coupled to a compression stage, considered in the reverse order of their series arrangement, that is to say, at least one turbine is coupled to a compression stage located upstream of a compression stage coupled to another turbine preceding it in the circulation loop,

[0009] - the expansion rate within the at least one turbine coupled to a compression stage is configured to generate a pressure drop of a certain value of the circulating gas, which differs by no more than 40% from the value of the pressure rise within the compression stage to which said turbine is coupled,

[0010] - the compression mechanism comprises only centrifugal compressors,

[0011] - the expansion mechanism comprises only radial turbines,

[0012] - the device comprises n turbines and k compressors, n and k being integers such that k > n,

[0013] - the mechanical coupling of the at least one turbine and of the one or more compression stages with the same shaft is configured to ensure the same or substantially the same rotational speed of the coupled turbines and compression stages,

[0014] - the device comprises sixteen compression stages and eight turbines, or twelve compression stages and six turbines, or eight compression stages and four turbines, or six compression stages and three turbines, or four compression stages and three turbines, or three compression stages and two or three turbines, or two compression stages and one or two turbines,

[0015] - the set of one or more heat exchangers comprises at least one heat exchanger in which two separate parts of the circulation loop are simultaneously circulated under separate thermodynamic conditions in countercurrent operation, respectively for cooling and heating the circulating gas.

[0016] The application also relates to a method for producing cryogenic hydrogen, in particular liquefied hydrogen, using a device according to any one of the above or below features, in which the pressure of the circulating gas at the inlet of the mechanism for compressing the circulating gas is between two bar absolute pressure and forty bar absolute pressure, and in particular between eight bar absolute pressure and thirty-five bar absolute pressure.

[0017] According to other possibilities, the cycle gas comprises at least one of: helium, hydrogen, nitrogen, neon, freon, hydrocarbons (to be refined), and / or the at least one member for cooling the cycle gas is configured to cool the cycle gas at the outlet of the at least one turbine or at the outlet of at least one of the turbines.

[0018] The present application can also relate to any alternative apparatus or method comprising any combination of the above or below features within the scope of the claims.

[0019] Further specific features and advantages will become apparent from the description given below, made with reference to the drawings, in which:

[0020] [ Figure 1 ] shows a schematic partial view showing the structure and operation of a first possible exemplary embodiment of the present application,

[0021] [ Figure 2 ] shows a schematic partial view showing the structure and operation of a second possible exemplary embodiment of the present application,

[0022] [ Figure 3 ] shows a schematic partial view showing the structure and operation of a third possible exemplary embodiment of the present application,

[0023] [ Figure 4 ] shows a schematic partial view showing the structure and operation of a fourth possible exemplary embodiment of the present application,

[0024] [ Figure 5 ] shows a schematic partial view showing the structure and operation of a fifth possible exemplary embodiment of the present application,

[0025] [ Figure 6 ] shows a schematic partial view showing a detail of the fourth possible exemplary embodiment of the present application, which shows a possible instance of the structure and operation of the motor-turbocompressor of the apparatus?

[0026] [ Figure 7 ] shows a schematic partial view showing an instance of coupled turbine and compressor impellers with respective inlet and outlet pressures,

[0027] [ Figure 8 ] shows a schematic partial view showing another simplified embodiment.

[0028] [ Figure 1The device 1 for liquefying a fluid illustrated in the figures can be intended for liquefying hydrogen, but can also be applicable to other gases, notably helium or any mixture. Likewise, the device can ensure the cooling or liquefaction of any other fluid: natural gas, helium, methane, biomethane, nitrogen, oxygen, neon, combinations of these gases. The device 1 comprises a circuit 3 for the fluid to be cooled, typically hydrogen, having an upstream end intended to be connected to a source 2 of gaseous fluid and a downstream end 23 intended to be connected to a member 4 for collecting the liquefied fluid. The source 2 can typically comprise an electrolyser, a hydrogen distribution network, a steam methane reforming (SMR) unit or one or more any other suitable source.

[0029] The device 1 comprises a set of heat exchangers 6, 7, 8, 9, 10, 11, 12, 13, arranged in series, in heat exchange with the circuit 3 for the fluid to be cooled. It is also conceivable to have a single heat exchanger.

[0030] The device 1 comprises at least one first cooling system 20, in heat exchange with at least one part of the set of heat exchangers 5, 6, 7, 8, 9, 10, 11, 12, 13.

[0031] This first cooling system 20 is a refrigerator carrying out a refrigeration cycle of a circulating gas.

[0032] This circulating gas comprises at least one of the following, for example: helium, hydrogen, nitrogen, neon, freon, hydrocarbon.

[0033] This refrigerator 20 comprises, arranged in series in a circulation loop 14, preferably closed in the form of a loop, the following components: a mechanism 15 for compressing the circulating gas, at least one member 16, 5, 6, 8, 10, 12 for cooling the circulating gas, a mechanism 17 for expanding the circulating gas and at least one member 13, 12, 11, 10, 9, 8, 7, 6, 5 for heating the expanded circulating gas.

[0034] As illustrated, the set of one or more heat exchangers for cooling the hydrogen to be liquefied preferably comprises one or more counterflow heat exchangers 5, 6, 8, 10, 12, arranged in series, and in which two separate parts of the circulation loop 14 circulate simultaneously in counterflow operation (for cooling and heating separate circulating gas flows, respectively).

[0035] That is to say, the plurality of counterflow heat exchangers forms both a member for cooling the circulating gas (for example, after compression and after the expansion stage) and a member for heating the circulating gas (after expansion and before returning to the compression mechanism).

[0036] The compression mechanism comprises at least two compression stages 15, formed by a set of centrifugal compressors arranged in series (and possibly in parallel).

[0037] The compression stages 15 can be formed by impellers of motorized centrifugal compressors.

[0038] The compression stages 15 (that is, the compressor impellers) are mounted on shafts 19, 190, which are driven in rotation by a set of electric motors 18 (at least one motor). Preferably, all the compressors 15 are of the centrifugal type.

[0039] The expansion mechanism itself comprises at least one expansion stage formed by one or more radial turbines 17 (if there are multiple expansion stages, the turbines are arranged at least partially in series. Preferably, all the turbines 17 are of the radial type and are arranged mainly in series).

[0040] At least one of the turbines 17 is coupled to the same shaft 19 as a compression stage 15 of the compressor, in order to provide the mechanical work produced during expansion to the compressor.

[0041] The coupled at least one turbine 17 and the corresponding compression stage are structurally configured so that the pressure P2t of the cycle gas leaving the turbine 17 and the pressure P1c of the cycle gas at the inlet of the compression stage 15 differ by no more than 40% and preferably by no more than 30% or no more than 20% (see Figure 7 ]).

[0042] Likewise, the coupled at least one turbine 17 and the corresponding compression stage are preferably also (or possibly alternatively) structurally configured so that the pressure of the cycle gas entering the turbine 17 and the pressure of the cycle gas at the outlet of the compression stage differ by no more than 40% and preferably by no more than 30% or no more than 20%.

[0043] This combination of specific technical features (centrifugal compression, radial expansion, transfer of work from the turbine to the compressor, and pressure regulation between the coupled compression impeller and expansion impeller) improves the efficiency of the device with respect to known solutions.

[0044] This structural configuration of the turbine (for example, turbine impeller) and the compression stage (for example, compression impeller) means that the two elements are dimensioned (if appropriate, the shape and / or size of the impeller and / or its volute and / or its inlet distributor) to perform compression and expansion, respectively, of the same or similar absolute values as indicated above. That is, by design, the two coupled elements can reach these compression and expansion ratios (without using another active or passive element in the cycle circuit), preferably independently of the conditions of the cycle gas flow.

[0045] For example, the expansion ratio within the at least one turbine 17 coupled to the compression stage can be configured to produce a pressure drop of the cycle gas, the value of which does not differ by more than 40% or more than 20% from the value of the pressure rise within the compression stage 15 coupled to said turbine.

[0046] For example, see Figure 7 If the compressor 15 is coupled to the turbine 17 and operates between 10 and 15 bars (compressing a flow initially at P1c= 10 bars to an outlet pressure P2c= 15 bars), it is advantageous for the turbine 17 to expand this flow to a pressure between 15 and 10 bars (P1t= 15 bars and P2t= 10 bars).

[0047] This improves the distribution and balance of the axial forces of the shaft 19 that supports them.

[0048] Since the signs of the forces generated by the pressure difference on the impellers 15, 17 are opposite, this tends to reduce the resultant of the axial forces.

[0049] This preferably also applies to the case where a plurality of turbines are coupled in series to one or more compressors 15.

[0050] Thus, as illustrated, the expansion mechanism can comprise at least two expansion stages in series constituted by a series of radial turbines 17 coupled in series.

[0051] In addition, in the direction of circulation of the cycle gas, the at least two turbines 17 in series are preferably respectively coupled to a compression stage 15, considered in the opposite order to their series arrangement. That is to say, at least one turbine 17 is coupled to a compression stage 15 upstream of the compression stage 15 coupled to another turbine 17 that precedes it in the circulation loop 14.

[0052] Preferably, the device comprises n turbines (expansion impellers or stages) and k compressor impellers or stages, with k >= n. The expansion ratio chosen within each turbine 17 is thus preferably imposed as a function of the compressor to which they are coupled (as explained above).

[0053] The device 1 can comprise one or more motor-turbocompressors in a part of the compression station. A motor-turbocompressor is an assembly comprising a motor whose shaft directly drives a set of one or more compression stages (impeller(s)) and a set of one or more expansion stages (turbine(s)). This directly exploits the mechanical expansion work at one or more compressors of the cycle gas.

[0054] The at least one means 16, 5, 6, 8, 10, 12 for cooling the circulating gas can possibly be configured to cool the circulating gas at the outlet of at least one of the turbines 17. That is to say, after expansion in the turbine 17, the circulating gas can be cooled typically by a value between 2 K and 30 K.

[0055] For example, and as illustrated, the device 1 comprises more compressor stages 15 than turbines 17, for example twice or approximately twice as many. Each turbine 17 can be coupled with a single respective compressor wheel 15 to the same shaft 19 driven by a respective electric machine 18. One or more other compressor wheels 15 (one or more stages) not coupled to a turbine 17 can be mounted only on a rotating shaft 190 driven by a separate respective electric machine 18 (electric machine-compressor).

[0056] As illustrated, the compressor stages 15 coupled to a turbine 17 and the compressors not coupled to a turbine 17 can alternate in series in the circulation loop 14.

[0057] The compression means can comprise more than six compressor stages in series. Of course, this is by no means limiting. The minimum compression rate for implementing the liquefaction of hydrogen (by centrifugal technology) should preferably be around 1.3 to 1.6.

[0058] The four compressor stages 15 in series make it possible to obtain very good isothermal efficiency, in particular with respect to the known solution of piston compression at the cost of a relatively significant helium mass flow.

[0059] In the non-limiting example illustrated in Figure 1 ] only four compressor stages 15 and three turbines 17 are shown, but the device 1 can comprise eight compressor stages 15 and four turbines 17. Any other distribution can be envisaged, for example sixteen compressor stages 15 and eight turbines 17, or twelve compressor stages and six turbines, or six compressor stages and three turbines, or four compressors and three turbines, or three compressor stages and two turbines (expansion stages), or two compressor stages and one expansion stage, etc.

[0060] The cooling can be provided downstream of all or some of the compressor stages or downstream of all or some of the compressors 15 (for example, by a heat exchanger 16 cooled by a heat transfer fluid or by any other refrigerant, in particular different from the circulating gas). This cooling can be provided after each compressor stage, or as illustrated, after every two (or more) compressor stages 15, or only downstream of the compression station. Surprisingly, this cooling distribution at every two (or three) compressor stages 15, and not at the outlet of each of the compressor stages 15 in series, makes it possible to obtain cooling performance while limiting the cost of the device 1.

[0061] Likewise, the at least one means for cooling the cycle gas can optionally comprise systems 8, 10, 12 for cooling the cycle gas, such as heat exchangers, provided in series at the outlet of at least some of the turbines 17.

[0062] This intermediate inter-expansion cooling makes it possible to limit the high pressure values required to reach the coldest temperature of the cycle gas.

[0063] As illustrated in [ Figure 1 ] the device 1 can comprise systems for cooling the cycle gas, such as heat exchangers, provided in series at the outlet of all the turbines 17, except the last one 17, in the direction of circulation of the cycle gas. As illustrated, this cooling system can be provided by the respective counterflow heat exchangers 8, 10, 12 described above.

[0064] This expansion followed by cooling makes it possible to implement a temperature staging (that is to say, makes it possible to reach different, decreasing temperatures after each expansion stage) to extract cold for the fluid to be cooled. This temperature staging is obtained by this arrangement and via the minimum compression ratio obtained for supplying these different turbines 17.

[0065] The arrangement of a plurality of centrifugal compression stages 15 upstream in series makes it possible to obtain this pressure difference, which makes it possible to implement a sufficient cooling staging downstream. In particular, for the same pressure difference, the more the temperature decreases, the more the enthalpy drop at constant entropy during expansion decreases. The effect of the turbine 17 arrangement in series and the cooling 8, 10 at the outlet of the turbines is to increase the average mass flow in the turbines 17 relative to the conventionally known staging. The theoretical isentropic efficiency therefore tends to increase and thus makes it possible to obtain a better efficiency of the turbines 17.

[0066] In particular, the cooling 8, 10 between the expansion stages allows the cycle fluid to reach the target liquefaction temperature without requiring even greater overall compression ratios. The expansion is preferably isentropic or quasi-isentropic. That is to say, the cycle fluid is progressively cooled and the fluid is liquefied.

[0067] Thus, the minimum temperature is reached directly at the outlet of the last quasi-isentropic expansion stage (that is to say, downstream of the last expansion turbine 17). Thus, for example, it is not necessary to additionally provide a Joule-Thomson type expansion valve downstream. The cold and in particular subcooled temperature of the hydrogen gas to be liquefied can be obtained with the turbines 17 alone (extracting work).

[0068] Preferably, most or all of the turbines 17 are coupled to one or more respective compressors 15.

[0069] As mentioned above, the successive turbo machines 17 are preferably coupled respectively to the compression stages 15 of the compressor, considered in the opposite order to that in which they are arranged in series. That is to say, for example, the turbo machines 17 are coupled to the compressors 15 upstream of the compressors 15 to which the turbo machines 17 preceding them are coupled.

[0070] Thus, preferably, the combined order of the coupled turbo machines 17 and compressors is at least partially reversed between turbo machines and compressors (in the cycle, the more upstream turbo machines are coupled to the more downstream compressors).

[0071] Thus, for example in the case of a structure with six compression stages 15 in series and three expansion stages in series, the first turbo machine 17 (that is to say, the first turbo machine 17 following the compressors) can be coupled in series to the fifth compressor 15 (fifth compression stage), while the second turbo machine 17 can be coupled in series to the third compressor 15 (third compression stage), the third turbo machine 17 can be coupled in series to the first compressor 15 (first compression stage). The other compressors 15 forming the other compression stages can not be coupled to turbo machines (motor-compressor systems, rather than motor-turbo compressors). Thus, the most powerful turbo machine 17 (the one most downstream) can be coupled to the first compression stage (the first compression stage intakes at low pressure in the cycle). At this relatively low level of pressure, the greater the compression rate of the compressor 15, the less the impact of the pressure drop at its level is felt (as is also the case for the other compressors 15).

[0072] Of course, this example above is in no way limiting. For example, the turbo machines 17 can be coupled respectively to the even-numbered compressors 15 (the first turbo machine coupled to the sixth compressor, the second turbo machine coupled to the fourth compressor, etc.) or coupled in series directly with the compressors (for example, the first turbo machine 17 coupled in series with the sixth compressor 15, the second turbo machine coupled in series with the fifth compressor, etc.).

[0073] In the example illustrated, in which the compressors 15 are alternately coupled to the turbines 17 and then uncoupled from the turbines, the working pressure of the turbines 17 can be set "one by one" or "two by two" to the working pressure of the compressors 15 (that is to say, the first turbine 17 works at the compression rate of the 5th or 6th compressor 15; likewise, the second turbine 17 works at the compression rate of the 3rd or 4th compressor, etc.). If one considers a pair of two compressors 15 in series (one compressor with a compression impeller coupled to a turbine, followed by one compressor with a compression impeller uncoupled from a turbine), the first of the two compressors will for example compress the cycle gas to a first pressure PA, while the second compressor will then compress this cycle gas to a second pressure PB, with PB > PA. The turbine 17 coupled to the first of the two compressors preferably expands the cycle gas from the second pressure PB to the first pressure PA. This can for example be obtained by adjusting the characteristics of this turbine 17 according to this constraint. For example, there is adjustment of the section of the distributor, calibrated to the flow rate reaching the turbine 17, which has an effect on the pressure drop generated in the distributor portion and turbine impeller portion.

[0074] Thus, for example when a turbine is coupled every two compression stages in series, the above detailed pressure relationship (inlet / outlet) between the coupled expansion stage and compression stage can thus apply separately to the compression stage supporting the turbine or to the series of two compression impellers in series. In addition, the mechanical coupling(s) of the turbine 17 and of the compression impeller 15 with the same shaft 19 are configured to preferably ensure the same (or substantially the same) rotational speed of the coupled turbine 17 and compression impeller 15. This makes it possible to directly and effectively exploit the expansion work in the device. If appropriate, the rotational speed of all the compression and turbine impellers can be equal to the same determined value.

[0075] Control means can optionally be provided for all or some of the compression stages. For example, a variable frequency drive ("VFD") can be provided for each motor 18 driving at least one compression stage. This makes it possible to independently adjust the speed of the multiple compression stages or of each compression stage, and thus to adjust the expansion, without using complex gear systems or drives and specific control means of the variable vanes connected upstream of one or more compression stages. This speed control means can be provided for the set of compressors or for each compression stage.

[0076] Preferably, the device 1 does not comprise flow valves or valves for reducing the pressure (pressure drop) in the circuit between the compression stages, between the expansion stages or downstream of the expansion of the cycle. Thus, only isolation valves for maintenance purposes can be provided in the cycle circuit 14.

[0077] That is, the operating point (speed, pressure) of the turbine 17 can be regulated only by the dimensional characteristics of the turbine 17 (for example, without a throttle valve at the turbine inlet). This increases the reliability of the device (there are no potential problems of failure of valves involved in the control of the process, since they are not present). Furthermore, this makes it possible to eliminate expensive auxiliary circuits (safety valves, etc.) and simplifies manufacturing (reduction in the number of lines to be isolated, etc.).

[0078] The use of a helium-based cycle gas makes it possible to reach the temperature for supercooling the liquefied hydrogen without the risk of zones below atmospheric pressure within the process (which would be dangerous if the cycle fluid were hydrogen gas) and without the risk of freezing of the cold source (the maximum liquefaction temperature of helium gas is equal to 5.17 K). The effect of supercooling the liquefied hydrogen has very significant advantages for the transport chain of the hydrogen molecules and then, due to the reduction in the evaporated gas during transport, potentially very significant advantages for the user (typically a liquid station).

[0079] Thus, the freezing point (13 K) of the hydrogen gas stream to be liquefied can be reached without crystallizing the cold source.

[0080] The low-pressure part of the cycle circuit 14 can be operated at a relatively high pressure. This makes it possible to reduce the volumetric flow rate in the heat exchangers 6, 7, 8, 9, 10, 11, 12, 13. Thus, the working pressure of the cycle gas can be decoupled from the pressure or target temperature of the fluid to be cooled. Thus, this pressure of the cycle gas can be increased to accommodate the constraints of the turbine, but also to reduce the volumetric flow rate at low pressure, which is often one of the main parameters determining the size of the heat exchangers.

[0081] This low-pressure level in the cycle circuit 14 is for example greater than or equal to 10 bars, and can typically be between 10 bars and 40 bars. This reduces the volumetric flow rate in the heat exchangers, which balances the low compression rate of each compression stage.

[0082] As illustrated, the device 1 can comprise a second cooling system, in thermal exchange with at least part of the set of one or more heat exchangers 5, in thermal exchange with the cycle gas. This second cooling system 21 comprises for example a circuit 25 for a heat transfer fluid such as liquid nitrogen or a refrigerant mixture, which cools the cycle gas and / or the hydrogen gas to be liquefied by one or more first counterflow heat exchangers and can also make it possible to prevent losses due to the differences induced at the hot end by the circulation of the heat transfer fluid(s) in the closed loop as illustrated in [ Figure 1 ] and also to prevent the freezing of the cold source.

[0083] This second cooling system 21 makes it possible to pre-cool the fluid to be liquefied and / or the working gas, for example at the outlet of the compression train. This refrigerant circulating in a circuit 25 for the heat transfer fluid, for example in a loop, is provided by a unit 27 for producing and / or storing 28 this refrigerant. If appropriate, the circuit 3 for the fluid to be cooled passes through this unit 27 in order to be pre-cooled upstream. It should be noted that one or more other additional cooling systems can be envisaged for the device 1. For example, in addition to the system described above, a third cooling circuit supplied by a chiller, for example providing a cold source at a temperature typically between 5°C and -60°C, can be provided. If necessary, a fourth cooling system can also be provided to provide the device 1 with cold again and increase the liquefaction capacity of the device 1. Figure 2 The embodiment of

[00017] differs from the previous one only in that the circulation loop 14 comprises a backflow pipe 22 having a first end connected to the outlet of one of the turbines 17, other than the last one downstream, and a second end connected to the inlet of one of the compressors 15, other than the first compressor 15 upstream. This backflow pipe 22 makes it possible to return a fraction of the circulation gas flow at an intermediate pressure level between the low pressure at the inlet of the compression train and the high pressure at the outlet of the compression train.

[0084] The backflow pipe 22 can exchange heat with at least part of the counterflow heat exchanger. According to the level of process optimisation desired, a plurality of backflow pipes to the compression station at intermediate pressures can advantageously be installed. For example, the extraction point (at the turbine considered) and the injection point (at the compression stage considered) can be at different pressure levels.

[0085] [ Figure 3 The embodiment of

[00017] differs from the previous one only in that the circulation loop 14 further comprises a partial bypass pipe 24 having a first end connected upstream of a turbine 17, for example the first upstream turbine 17, and a second end connected to the inlet of another turbine 17 located downstream, for example the third turbine. The bypass pipe 24 makes it possible, for example, to divert a fraction of the circulation gas flow leaving the compression train at high pressure towards a cooler turbine further downstream. The remainder of the flow passes through this first upstream turbine 17, which is hotter. This makes it possible to adjust the flow sent to the different stages according to the positioning in terms of the specific speed of the different turbines and compressors. For example, the compressors take in a lower volumetric flow at a higher pressure than the first compression stage (close to the low pressure of the process). One way of increasing this volumetric flow and thus potentially increasing its isentropic efficiency is to incorporate a backflow at intermediate pressure from an expansion stage, as shown in

[00017] . Figure 3

[0086] [ Figure 4 ​The device 1 shown in the figure illustrates yet another non-limiting embodiment. Elements identical to those described above are indicated by the same reference numerals and will not be described in detail again.

[0087] [ Figure 4 The circulation loop 14 of the device includes three compressors (each driven by a motor 18). As shown, each compressor may include four compression stages 15 (that is, four compression impellers in series). These compressor impellers 15 can be mounted by direct coupling to one end of the shaft 19 of the motor 18. In this example, the device therefore has twelve centrifugal compression stages in series. As shown, cooling 26 of the circulating gas can be provided for every two compression stages.

[0088] In this example, device 1 has five expansion stages in series (six radial turbine impellers, two of which are arranged in parallel), for example, one or two expansion stages per compressor. As shown, all turbines 17 can be coupled to compressor shaft 19 (e.g., two turbines 17 are mounted on the other end of the shaft 19 of each motor 18 to provide mechanical work to compressor impellers 15, which are also mounted on this shaft 19). Of course, the turbines 17 can be on the same side of the shaft 19 as the compressor impellers 15. For example, four first expansion stages are formed by four turbines 17 in series. A fifth expansion stage is formed, for example, by two turbines 17 respectively arranged in two parallel branches of the circulation loop 14.

[0089] [ Figure 5 The device 1 shown in the figure and [ Figure 4 The difference in the device is that it includes return lines 122, 123, and 124 for the circulating gas, which carry a portion of the circulating gas exiting turbine 17 at an intermediate pressure level (medium pressure) within the compression mechanism. For example, line 124 connects the outlet of the first turbine to the outlet of the eighth compression stage. Similarly, line 123 connects the outlet of the second turbine to the outlet of the sixth compression stage. Similarly, line 122 connects the outlet of the third turbine 17 to the outlet of the fourth compression stage. Of course, the device may have only one or only two of these intermediate pressure return lines. Similarly, other return lines are conceivable. Furthermore, the ends of these lines can be varied (one or more outlets of other turbines and one or more outlets of other compression stages).

[0090] This one or more recirculations enable the compressor's volumetric flow rate to be increased, thus supplying an excess flow and potentially increasing their isentropic efficiency.

[0091] [ Figure 6The device 1 illustrated in Figure 1 illustrates details of the device 1 which illustrate non-limiting possible examples of the structure and operation of the motor-turbocompressor arrangement. One end of the shaft 19 of the motor 18 drives four compressor impellers (four compression stages 15). The other end of the shaft 19 is directly coupled to two expansion stages (two turbines 17).

[0092] Of course, any other suitable type of arrangement (number and distribution) of compression stages 15 and expansion stages 17 can be envisaged (as well as for the number of motors).

[0093] Therefore, other modifications are possible.

[0094] Therefore, various configurations are possible for the turbines 17, and especially for the downstream turbines (the coldest turbines).

[0095] For example, as already illustrated, the last two expansion stages (two turbines) can be installed in parallel instead of in series. This makes it possible to achieve a greater enthalpy drop within these turbines. This will be achieved at the expense of efficiency (as the two turbines will share 100% of the flow and the available pressure difference will almost be doubled). Although the efficiency of these last two expansion stages can decrease, achieving a greater enthalpy drop can make it possible to grade the expansion more efficiently.

[0096] This is because the same enthalpy difference in cold conditions leads to a temperature change within the turbine which is less than the temperature change in the case of a hotter turbine. This improves the efficiency of the refrigeration and liquefaction process. Therefore, although the temperature difference within the turbine is relatively reduced, the efficiency of the device makes it possible to liquefy the hydrogen with good energy efficiency.

[0097] The temperature difference induced by the turbines 17 can be a function of the temperature of the circulating gas upstream of the turbines 17.

[0098] A buffer tank (not illustrated) and a set of valves can be provided, preferably at low pressure levels, the aim being to limit the maximum pressure with which the cooling circuit is filled with gas. Preferably, the minimum compression ratio within the compression station is between 1.3 and 1.6. For example, the circulating gas can consist of 100% or 99% helium and be supplemented with hydrogen.

[0099] The circulation circuit can comprise, at the inlet of at least one of the turbines 17, inlet guide vanes (“IGVs”) configured to regulate the flow of fluid to a determined operating point.

[0100] In addition, the arrangement of the compressor wheels 15 and / or turbines 17 is not limited to the above examples. Thus, the number and arrangement of the compressors 15 can be modified. For example, the compressor train can consist of only three compressors, each of which can be provided with a plurality of compression stages, for example three compression stages, that is to say three compressor wheels (with or without inter-stage cooling).

[0101] [ Figure 8 ] shows another example with two compression stages (wheels) in series and one expansion stage (wheel).

[0102] Likewise, two compression stages 15 can be arranged in parallel and in series with other compression stages (for example three in series). The two compression stages in parallel can be placed upstream of the other compression stages and thus provide a relatively high flow at low pressure in the downstream direction by using machines which can all be identical.

[0103] In the same way, the turbines 17 can be placed in parallel in the circulation loop 14.

[0104] In addition, as already shown, all the turbines can be coupled to one or more compressor wheels (for example, one or more turbines 17 coupled to the same shaft 19 as one or more compression stages).

[0105] As shown, the circuit 3 for the fluid to be cooled can comprise one or more catalytic means (one or more converters 280), for example for (ortho-para) hydrogen conversion, at the outside of the exchanger or at one or more portions 29 of one or more exchangers.

Claims

1. An apparatus for cooling and / or liquefying a fluid, the apparatus comprising a circuit (3) for the fluid to be cooled, the circuit having an upstream end intended to be connected to a fluid source (2) and a downstream end (23) intended to be connected to a component (4) for collecting the fluid, the apparatus (1) comprising one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​of a group for heat exchange with the circuit (3) for the fluid to be cooled, the apparatus (1) comprising at least one first cooling system (20) for heat exchange with at least a portion of the one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​of the group, the first cooling system (20) being a refrigerator for cooling a circulating gas, the refrigerator comprising the following components arranged in series in the circulating circuit (14): a compression mechanism for compressing the circulating gas. (15) at least one component (16, 5, 6, 8, 10, 12) for cooling the circulating gas, an expansion mechanism (17) for expanding the circulating gas, and at least one component (13, 12, 11, 10, 9, 8, 7, 6, 5) for heating the expanded circulating gas, wherein the compression mechanism (15) comprises a plurality of compression stages in series consisting of a set of centrifugal impeller compressors mounted on a shaft (19, 190) driven to rotate by a set of motors (18), the expansion mechanism (17) comprises at least one expansion stage consisting of a set of centrifugal turbines having a defined working pressure at the inlet, and wherein the turbine, or correspondingly at least one of these turbines, is coupled to the same shaft (19) as at least one compression stage so as to provide the mechanical work generated during expansion to the compression stage, characterized in that, The at least one turbine and the corresponding compression stage are structurally configured such that the pressure of the circulating gas exiting the turbine differs from the pressure of the circulating gas at the inlet of the compression stage by no more than 40%, and the at least one turbine and the corresponding compression stage are structurally configured such that the pressure of the circulating gas entering the turbine differs from the pressure of the circulating gas at the outlet of the compression stage by no more than 40%, and the expansion rate within the at least one turbine connected to the compression stage is configured to generate a pressure drop in the circulating gas, the value of which differs from the pressure rise within the compression stage connected to the turbine by no more than 40%.

2. The apparatus as claimed in claim 1, characterized in that, The fluid is hydrogen and / or helium.

3. The apparatus as described in claim 1, characterized in that, The at least one turbine and the corresponding compression stage are structurally configured such that the pressure of the circulating gas leaving the turbine differs from the pressure of the circulating gas at the inlet of the compression stage by no more than 30%.

4. The apparatus as described in claim 3, characterized in that, The at least one turbine and the corresponding compression stage are structurally configured such that the pressure of the circulating gas leaving the turbine differs from the pressure of the circulating gas at the inlet of the compression stage by no more than 20%.

5. The apparatus as claimed in claim 1, characterized in that, The at least one turbine and the corresponding compression stage are structurally configured such that the pressure of the circulating gas entering the turbine differs from the pressure of the circulating gas at the outlet of the compression stage by no more than 30%.

6. The apparatus as claimed in claim 1, characterized in that, The at least one turbine and the corresponding compression stage are structurally configured such that the pressure of the circulating gas entering the turbine differs from the pressure of the circulating gas at the outlet of the compression stage by no more than 20%.

7. The apparatus as claimed in claim 1, characterized in that, The expansion mechanism (17) includes at least two expansion stages connected in series, consisting of a set of centripetal turbines connected in series, wherein, in the circulation direction of the circulating gas, the at least two turbines connected in series are respectively connected to a compression stage, in reverse order of their series connection, that is, at least one turbine is connected to a compression stage located upstream of another turbine connected to it in the circulation loop (14).

8. The apparatus according to any one of claims 1 to 7, characterized in that, The compression mechanism (15) consists only of a centrifugal compressor.

9. The apparatus according to any one of claims 1 to 7, characterized in that, The expansion mechanism (17) consists only of a centripetal turbine.

10. The apparatus as claimed in claim 8, characterized in that, The expansion mechanism (17) consists only of a centripetal turbine.

11. The apparatus according to any one of claims 1 to 7, characterized in that, The device comprises n turbines and k compressors, where n and k are integers such that k is greater than or equal to n.

12. The apparatus as claimed in claim 8, characterized in that, The device comprises n turbines and k compressors, where n and k are integers such that k is greater than or equal to n.

13. The apparatus as claimed in claim 9, characterized in that, The device comprises n turbines and k compressors, where n and k are integers such that k is greater than or equal to n.

14. The apparatus as claimed in claim 10, characterized in that, The device comprises n turbines and k compressors, where n and k are integers such that k is greater than or equal to n.

15. The apparatus according to any one of claims 1 to 7, characterized in that, The mechanical connection of the at least one turbine and the one or more compression stages to the same shaft (19) is configured to ensure that the connected turbine and these compression stages rotate at the same or substantially the same speed.

16. The apparatus as claimed in claim 8, characterized in that, The mechanical connection of the at least one turbine and the one or more compression stages to the same shaft (19) is configured to ensure that the connected turbine and these compression stages rotate at the same or substantially the same speed.

17. The apparatus as claimed in claim 9, characterized in that, The mechanical connection of the at least one turbine and the one or more compression stages to the same shaft (19) is configured to ensure that the connected turbine and these compression stages rotate at the same or substantially the same speed.

18. The apparatus as claimed in claim 11, characterized in that, The mechanical connection of the at least one turbine and the one or more compression stages to the same shaft (19) is configured to ensure that the connected turbine and these compression stages rotate at the same or substantially the same speed.

19. The apparatus as claimed in claim 14, characterized in that, The mechanical connection of the at least one turbine and the one or more compression stages to the same shaft (19) is configured to ensure that the connected turbine and these compression stages rotate at the same or substantially the same speed.

20. The apparatus according to any one of claims 1 to 7, characterized in that, The device includes sixteen compression stages and eight turbines, or twelve compression stages and six turbines, or eight compression stages and four turbines, or six compression stages and three turbines, or four compression stages and three turbines, or three compression stages and two or three turbines, or two compression stages and one or two turbines.

21. The apparatus as claimed in claim 8, characterized in that, The device includes sixteen compression stages and eight turbines, or twelve compression stages and six turbines, or eight compression stages and four turbines, or six compression stages and three turbines, or four compression stages and three turbines, or three compression stages and two or three turbines, or two compression stages and one or two turbines.

22. The apparatus as claimed in claim 9, characterized in that, The device includes sixteen compression stages and eight turbines, or twelve compression stages and six turbines, or eight compression stages and four turbines, or six compression stages and three turbines, or four compression stages and three turbines, or three compression stages and two or three turbines, or two compression stages and one or two turbines.

23. The apparatus as claimed in claim 11, characterized in that, The device includes sixteen compression stages and eight turbines, or twelve compression stages and six turbines, or eight compression stages and four turbines, or six compression stages and three turbines, or four compression stages and three turbines, or three compression stages and two or three turbines, or two compression stages and one or two turbines.

24. The apparatus as claimed in claim 15, characterized in that, The device includes sixteen compression stages and eight turbines, or twelve compression stages and six turbines, or eight compression stages and four turbines, or six compression stages and three turbines, or four compression stages and three turbines, or three compression stages and two or three turbines, or two compression stages and one or two turbines.

25. The apparatus as claimed in claim 19, characterized in that, The device includes sixteen compression stages and eight turbines, or twelve compression stages and six turbines, or eight compression stages and four turbines, or six compression stages and three turbines, or four compression stages and three turbines, or three compression stages and two or three turbines, or two compression stages and one or two turbines.

26. The apparatus according to any one of claims 1 to 7, characterized in that, One or more heat exchangers in the group include at least one heat exchanger (5,6,7,8,9,10,11,12,13), wherein two separate sections of the circulation loop (14) circulate simultaneously in countercurrent operation under separate thermodynamic conditions for cooling and heating the circulating gas, respectively.

27. The apparatus as claimed in claim 8, characterized in that, One or more heat exchangers in the group include at least one heat exchanger (5,6,7,8,9,10,11,12,13), wherein two separate sections of the circulation loop (14) circulate simultaneously in countercurrent operation under separate thermodynamic conditions for cooling and heating the circulating gas, respectively.

28. The apparatus as claimed in claim 9, characterized in that, One or more heat exchangers in the group include at least one heat exchanger (5,6,7,8,9,10,11,12,13), wherein two separate sections of the circulation loop (14) circulate simultaneously in countercurrent operation under separate thermodynamic conditions for cooling and heating the circulating gas, respectively.

29. The apparatus as claimed in claim 11, characterized in that, One or more heat exchangers in the group include at least one heat exchanger (5,6,7,8,9,10,11,12,13), wherein two separate sections of the circulation loop (14) circulate simultaneously in countercurrent operation under separate thermodynamic conditions for cooling and heating the circulating gas, respectively.

30. The apparatus as claimed in claim 15, characterized in that, One or more heat exchangers in the group include at least one heat exchanger (5,6,7,8,9,10,11,12,13), wherein two separate sections of the circulation loop (14) circulate simultaneously in countercurrent operation under separate thermodynamic conditions for cooling and heating the circulating gas, respectively.

31. The apparatus as claimed in claim 20, characterized in that, One or more heat exchangers in the group include at least one heat exchanger (5,6,7,8,9,10,11,12,13), wherein two separate sections of the circulation loop (14) circulate simultaneously in countercurrent operation under separate thermodynamic conditions for cooling and heating the circulating gas, respectively.

32. The apparatus as claimed in claim 25, characterized in that, One or more heat exchangers in the group include at least one heat exchanger (5,6,7,8,9,10,11,12,13), wherein two separate sections of the circulation loop (14) circulate simultaneously in countercurrent operation under separate thermodynamic conditions for cooling and heating the circulating gas, respectively.

33. The apparatus according to any one of claims 1 to 7, characterized in that, The device includes a second cooling system that exchanges heat with at least a portion of one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​in the group, the second cooling system (21) including a loop (25) for heat transfer fluid.

34. The apparatus as claimed in claim 8, characterized in that, The device includes a second cooling system that exchanges heat with at least a portion of one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​in the group, the second cooling system (21) including a loop (25) for heat transfer fluid.

35. The apparatus as claimed in claim 9, characterized in that, The device includes a second cooling system that exchanges heat with at least a portion of one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​in the group, the second cooling system (21) including a loop (25) for heat transfer fluid.

36. The apparatus as claimed in claim 11, characterized in that, The device includes a second cooling system that exchanges heat with at least a portion of one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​in the group, the second cooling system (21) including a loop (25) for heat transfer fluid.

37. The apparatus as claimed in claim 15, characterized in that, The device includes a second cooling system that exchanges heat with at least a portion of one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​in the group, the second cooling system (21) including a loop (25) for heat transfer fluid.

38. The apparatus as claimed in claim 20, characterized in that, The device includes a second cooling system that exchanges heat with at least a portion of one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​in the group, the second cooling system (21) including a loop (25) for heat transfer fluid.

39. The apparatus as claimed in claim 26, characterized in that, The device includes a second cooling system that exchanges heat with at least a portion of one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​in the group, the second cooling system (21) including a loop (25) for heat transfer fluid.

40. The apparatus as claimed in claim 32, characterized in that, The device includes a second cooling system that exchanges heat with at least a portion of one or more heat exchangers (5,6,7,8,9,10,11,12,13) ​​in the group, the second cooling system (21) including a loop (25) for heat transfer fluid.

41. The apparatus as claimed in claim 33, characterized in that, The heat transfer fluid is liquid nitrogen or a mixture of refrigerants.

42. A method for producing cryogenic hydrogen using the apparatus (1) as described in any one of claims 1 to 41, wherein, The pressure of the circulating gas at the inlet of the compression mechanism (15) used to compress the circulating gas is between two bar absolute pressure and forty bar absolute pressure.

43. The apparatus as claimed in claim 42, characterized in that, The low-temperature hydrogen gas is liquefied hydrogen.

44. The apparatus as claimed in claim 42, characterized in that, The pressure of the circulating gas at the inlet of the compression mechanism (15) used to compress the circulating gas is between eight bar absolute pressure and thirty-five bar absolute pressure.

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