Integrated expansion generator for hydrogen applications with magnetic bearings

Abstract

An expansion generator (100) for hydrogen applications has a machine inlet (111) and a machine outlet (112), and includes an impeller (110) that expands hydrogen and is directly connected to a generator (120), and at least one magnetic bearing (130) cooled by a flow of hydrogen obtained from the machine inlet (111). The expansion generator (100) is located within a housing (140), and preferably hydrogen flows through a suitable path within the housing (140) to cool the at least one magnetic bearing (130). Advantageously, the generator (120) is also cooled by the hydrogen stream obtained from the machine inlet (111).

Description

[0001] manual Technical Field

[0002] The presently disclosed subject matter relates to hydrogen expander generators with magnetic bearings. More particularly, the presently disclosed subject matter relates to an integrated expander generator that allows the use of hydrogen as a cooling fluid for the magnetic bearings and possibly the generator. Background Art

[0003] A hydrogen expansion generator is a rotary machine that expands a fluid through an impeller to release expansion work, thereby driving the impeller to rotate. Typically, the impeller is mechanically coupled to a transmission mechanism that transmits the rotation to the shaft of the generator, thereby generating electrical energy. If both the impeller and the generator are housed in a common housing, it is called an integrated machine.

[0004] Hydrogen applications are becoming increasingly important in energy conversion; however, several disadvantages and potential risks of using hydrogen in rotary machines, particularly in expansion generators, are known. For example, documents CN113374538A and CN113374581A aim to overcome the hydrogen leakage problem in expansion generators for hydrogen applications, which may cause explosion hazards due to the small critical ignition energy of hydrogen. According to these documents, a rotating seal (such as a rotating seal produced by a dry gas seal) is formed between the rotating shaft and the housing by using an inert gas and an isolation gas (such as nitrogen). In addition, it is known from document CN113513580A to use a lubrication system to lubricate the reduction box located between the hydrogen expander and the generator, thereby reducing the rotation speed of the generator shaft, thereby generally in order to achieve the rotation speed requirements of the mechanical bearings and other rotating mechanical parts.

[0005] However, it is desirable to have a safe high speed rotating machine without the need to introduce working gases and / or liquids (such as sealing gases or lubrication). Summary of the invention

[0006] According to one aspect, the subject matter disclosed in the present invention relates to an expansion generator that receives hydrogen from a machine inlet and discharges expanded hydrogen to a machine outlet, the expansion generator including an impeller mechanically connected to the generator and also including at least one magnetic bearing cooled by a hydrogen gas stream obtained from the machine inlet. The expansion generator is located inside a housing. According to some embodiments, the hydrogen gas stream obtained from the machine inlet flows through an appropriate path within the housing to cool at least the magnetic bearings. Advantageously, the generator is also cooled by the hydrogen gas stream obtained from the machine inlet. According to some embodiments, the hydrogen gas is used only to cool the generator and not the magnetic bearings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A more complete appreciation thereof will be readily obtained as the disclosed embodiments of the present invention and many of its attendant advantages become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which:

[0008] Figure 1 shows a schematic diagram of a first embodiment of an innovative expansion generator in which radial magnetic bearings are cooled by hydrogen from the machine inlet,

[0009] Figure 2 shows a schematic diagram of a second embodiment of the innovative expander generator, wherein the radial magnetic bearings are cooled by hydrogen from the machine inlet and the expander generator discharges heated hydrogen at the machine outlet,

[0010] Figure 3 shows a schematic diagram of a third embodiment of an innovative expansion generator in which the radial magnetic bearings and the thrust magnetic bearings are cooled by hydrogen from the machine inlet, the expansion generator exhausts the heated hydrogen at the machine outlet, and the generator is cooled by a cooling fluid,

[0011] Figure 4 A schematic diagram of a fourth embodiment of an innovative expander generator is shown, wherein a portion of the radial magnetic bearings, thrust magnetic bearings and generator are cooled by a first hydrogen gas stream and a portion is cooled by a second hydrogen gas stream (both hydrogen gas streams are from the machine inlet), and the expander generator discharges heated hydrogen at the machine outlet,

[0012] Figure 5 A schematic diagram of a fifth embodiment of an innovative expander generator is shown, wherein the radial magnetic bearings, the thrust magnetic bearings and the generator are cooled by the same hydrogen gas stream from the machine inlet, and the expander generator exhausts heated hydrogen at the machine outlet, and

[0013] Figure 6 A schematic diagram of a sixth embodiment of the innovative expansion generator is shown, in which a portion of the radial magnetic bearings, thrust magnetic bearings and generator are cooled by a first hydrogen gas stream from a machine inlet and a portion is cooled by a second hydrogen gas stream from a machine outlet, and the expansion generator exhausts heated hydrogen at the machine outlet. DETAILED DESCRIPTION

[0014] According to one aspect, the subject matter disclosed in the present invention relates to a rotary machine for generating electrical energy, which expands hydrogen through an impeller, which rotates due to the energy released during the expansion of the hydrogen. The impeller receives hydrogen from the machine inlet; the hydrogen expands through the impeller while flowing through the impeller blades, and finally the expanded hydrogen is discharged to the machine outlet. The impeller is directly connected to the shaft of a generator, which has a rotating part integral with the shaft and a stator part integral with the housing, and generates a rotating magnetic field due to the rotation of the shaft, thereby generating electrical energy. A first part of the hydrogen fed to the machine inlet is deflected and used to cool at least one magnetic bearing (which can be a radial bearing or a thrust bearing) acting on the shaft, and is then advantageously sent to the machine outlet to mix with the hydrogen expanded and discharged by the impeller. Advantageously, a second part of the hydrogen fed to the machine inlet is deflected and used to cool the generator. It should be noted that according to some embodiments, the first part of the hydrogen used to cool at least one magnetic bearing and the second part of the hydrogen used to cool the generator can be the same hydrogen flow.

[0015] Reference will now be made in detail to embodiments of the present disclosure, examples of which are shown in the accompanying drawings. Examples and drawings are provided in a manner to explain the present disclosure, and these examples and drawings should not be construed as limitations on the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the scope or essence of the present disclosure. In the following description, similar reference numerals are used to illustrate the drawings of the embodiments to indicate elements that perform the same or similar functions. In addition, for clarity of description, some reference numerals may not be repeated in all drawings.

[0016] Figure 1 A first embodiment of an innovative expansion generator (hereinafter "expansion generator") is schematically illustrated and generally indicated by reference numeral 100. In addition, for the sake of clarity, the expansion generator is shown in FIG. Figure 1 In the Figures (and in general, in all Figures), the fully schematic cycle of hydrogen gas in the expander generator is highlighted (see the multiple black arrows in the Figure). It is noted that other fluids may be circulated within the expander generator (as will be explained below). In general, non-limiting reference is made to Figure 1 The expansion generator 100 has a machine inlet 111 and a machine outlet 112 , and includes an impeller 110 configured to expand hydrogen and a generator 120 configured to generate electrical energy, both of which are accommodated in a housing 140 .

[0017] The impeller 110, in particular a radial inflow turbine, is configured to receive compressed hydrogen fed to the inlet 111 of the machine and expand it, thereby releasing expansion work; for example, Figure 1, two machine inlets 111 are shown positioned opposite each other with respect to the central axis A of the expansion generator 100. In particular, the impeller 110 has a plurality of impeller blades defining a plurality of channels through which hydrogen flows and expands before being discharged as expanded hydrogen at the machine outlet 112. Thus, the hydrogen fed to the impeller 110 reduces pressure and temperature from the inlet 111 to the outlet 112 of the machine. Typically, the compressed hydrogen fed to the machine inlet 111 is already at a very low temperature, for example from -230°C to -150°C.

[0018] As previously mentioned, the expansion of hydrogen through the impeller 110 releases expansion work, thereby driving the impeller 110. Figure 1 The impeller 110 is mechanically connected, in particular directly (ie without further elements therebetween), to a generator 120, which is preferably a permanent magnet generator.

[0019] More specifically, the generator 120 comprises a rotating hub 121 and a rotating magnetic assembly 122 mechanically coupled to the rotating hub 121, wherein the impeller 110 is mechanically connected to the rotating hub 121 of the generator 120. In particular, the rotating hub 121 has a cylindrical shape and comprises a recess, typically a tubular recess, located on the outer surface of the rotating hub 121, which accommodates the rotating magnetic assembly 122, advantageously a permanent magnet rotating magnetic assembly.

[0020] The generator 120 also includes a stationary magnetic assembly 123, advantageously including an electromagnet, which is arranged around the rotating magnetic assembly 122 (i.e., facing the rotating magnetic assembly 122). Advantageously, the stationary magnetic assembly 123 and the rotating magnetic assembly 122 define a gap therebetween. As will be better described below, according to one or more embodiments, the expansion generator 100 may also include a cooling system configured to circulate a cooling fluid to cool the rotating magnetic assembly 122 and / or the stationary magnetic assembly 123 of the generator 120. In particular, the cooling fluid may circulate in the gap between the rotating magnetic assembly 122 and the stationary magnetic assembly 123.

[0021] Non-restrictive reference Figure 1 The expansion generator 100 further comprises at least one magnetic bearing 130 acting on the rotating hub 121, in particular supporting the rotating hub 121. Figure 1In an embodiment of the present invention, at least one magnetic bearing 130 is a radial magnetic bearing. Preferably, at least one magnetic bearing 130 is located between the impeller 110 and the rotating magnetic assembly 122 and the fixed magnetic assembly 123 of the generator 120. It should be noted that the housing 140 also accommodates at least one magnetic bearing 130. In particular, the rotating element of at least one magnetic bearing 130 is integrated with the rotating hub 121, and the stator element of at least one magnetic bearing 130 is integrated with the housing 140.

[0022] like Figure 1 As shown, at least one magnetic bearing 130 is fluidly coupled to the machine inlet 111 and is configured to be cooled by a hydrogen gas flow obtained from the machine inlet 111. In other words, a portion of the hydrogen fed to the machine inlet 111 is not expanded by the impeller 110, but is supplied to the at least one magnetic bearing 130 to cool it. In particular, the hydrogen may flow at least in a gap between a rotating element and a stator element of the at least one magnetic bearing 130. It is noted that the portion of hydrogen used to cool the at least one magnetic bearing 130 may be defined as "a small amount" if compared to the amount of hydrogen expanded by the impeller 110.

[0023] Non-restrictive reference Figure 1 , the expansion generator 100 further comprises a fluid conduit 113 fluidly coupling the machine inlet 111 and the at least one magnetic bearing 130; in particular, the expansion generator 100 has one fluid conduit 113 for each machine inlet 111. Advantageously, the fluid conduit 113 is at least partially defined by the rear surface of the impeller 110; more advantageously, the fluid conduit 113 is at least partially defined by the rear surface of the impeller 110 and the inner wall of the housing 140. In other words, the hydrogen supplied to the at least one magnetic bearing 130 flows partially through the fluid conduit 113. Preferably, one or more sealing elements are located upstream of the at least one magnetic bearing 130, such as labyrinth seals and / or sliding ring seals. For example, the seal may be located in the fluid conduit 113 or at the rotating hub 121, in particular between the impeller 110 and the at least one magnetic bearing 130. It should be noted that the temperature of the hydrogen downstream of the magnetic bearing 130 is higher than the temperature upstream of the magnetic bearing 130 (hence, it can be referred to as "heated hydrogen") due to the heat removed from the bearing. According to Figure 1 In the illustrated embodiment, the heated hydrogen downstream of the magnetic bearing 130 is exhausted outside of the housing 140. Advantageously, the hydrogen flows through a dedicated passage defined in the housing 140 that allows the hydrogen to flow out of the housing 140.

[0024] Preferably, the impeller 110 also includes at least one internal channel 114, which fluidly connects the fluid conduit 113 and the impeller blades so that the pressure (and therefore the force) acting on the impeller, in particular on the rear surface of the impeller and the front surface of the impeller (i.e., the surface where the impeller blades are located) is balanced.

[0025] The following will use Figure 2 A second embodiment 200 of an expansion generator is described. Note that Figure 2 The elements 210, 211, 212, 213, 214, 220, 221, 222, 223, 230 and 240 in the embodiment may be respectively Figure 1 Elements 110 (impeller), 111 (machine inlet), 112 (machine outlet), 113 (fluid conduit), 114 (internal passage), 120 (generator), 121 (rotating hub), 122 (rotating magnetic assembly), 123 (stationary magnetic assembly), 130 (magnetic bearing), and 140 (housing) are the same or similar and perform the same or similar functions. Note also that Figure 1 and Figure 2 The only difference between the two is the circulation of hydrogen in the machine, as will be apparent from the following.

[0026] according to Figure 2 In an embodiment of the present invention, at least one magnetic bearing 230 (particularly a radial magnetic bearing) is also fluidly coupled to the machine outlet 212, so that a cooling fluid (i.e., hydrogen from the machine inlet 211) flows through the fluid conduit 213, removes heat from the at least one magnetic bearing 230, and is then discharged to the machine outlet 212. In other words, the at least one magnetic bearing 230 is configured to discharge a heated hydrogen gas stream at the outlet 212; in particular, the heated hydrogen gas exhausted by the at least one magnetic bearing 230 is mixed with the expanded hydrogen gas expanded by the impeller 210 at the machine outlet 212 (see the black arrows starting from downstream of the radial magnetic bearing 230 and ending at the machine outlet 212).

[0027] Please note that Figure 1 The rotating hub 121 and Figure 2 The rotating hub 221 is longer than the housing 140 and 240; in other words, the rotating hub 121 and 221 can end outside the housing 140 and 240. As is known, the rotating shaft or rotating hub is advantageously supported by two radial magnetic bearings, which are usually located at both ends of the rotating shaft or rotating hub. According to one possibility, the rotating hub 121 and 221 can be supported by a second bearing (which can be a rolling bearing or a magnetic bearing) located outside the housing 140 and 240.

[0028] The following will use Figure 3 A third embodiment 300 of an expansion generator is described. Note that Figure 3 The elements 310, 311, 312, 313, 314, 320, 321, 322, 323, 330 and 340 in Figure 1Elements 110 (impeller), 111 (machine inlet), 112 (machine outlet), 113 (fluid conduit), 114 (internal passage), 120 (generator), 121 (rotating hub), 122 (rotating magnetic assembly), 123 (stationary magnetic assembly), 130 (magnetic bearing) and 140 (housing) are the same or similar and perform the same or similar functions.

[0029] according to Figure 3 In an embodiment of the invention, the expansion generator 300 has two magnetic bearings, in particular a radial magnetic bearing 330 and a thrust magnetic bearing 331 located downstream of the radial magnetic bearing 330. It should be noted that, according to a possibility not shown in any of the figures, the positions of the bearings can also be exchanged (i.e. the thrust magnetic bearing 331 can be located upstream of the radial magnetic bearing 330). Both the magnetic bearings 330 and 331 can be cooled by a stream of compressed hydrogen from the machine inlet 311, in particular they can be cooled in series. As described above, part of the hydrogen fed to the machine inlet 311 is, for example, first supplied to the radial magnetic bearing 330 and then to the thrust magnetic bearing 331 in order to cool them, in particular flowing at least in the gap between the rotating elements and the stator elements of the magnetic bearings 330 and 331 (see Figure 3 ). As described above, a portion of the hydrogen gas may flow from the machine inlet 311 through the fluid conduit 313 defined by the rear surface portion of the impeller 310 to reach the magnetic bearings 330 and 331. It is noted that the hydrogen gas may be pumped by the disk of the thrust magnetic bearing 331 (which may have one or more appropriately shaped pumping surfaces and / or one or more appropriately shaped pumping devices) and, for example, radially discharged from the thrust magnetic bearing 331.

[0030] Note that the temperature of the hydrogen downstream of the magnetic bearings 330 and 331 is higher than the temperature upstream of the magnetic bearings 330 and 331 (hence, it can be referred to as "heated hydrogen") due to the heat removed from the bearings. Advantageously, the heated hydrogen downstream of the magnetic bearings 330 and 331 is discharged to the outlet 312 and mixed with the hydrogen expanded by the impeller 310.

[0031] according to Figure 3In the embodiment shown, the rotating magnetic assembly 322 and possibly the stationary magnetic assembly 323 are cooled by a cooling fluid, in particular a cooling fluid supplied by an external source. It is noted that this is particularly useful for minimizing the pressure losses of the machine; in fact, the magnetic bearings 330 and 331 can be cooled by a portion of the hydrogen fed to the machine inlet 311, while the generator 320 can be cooled by one or more cooling fluids, which can have a lower pressure relative to the hydrogen used to cool the magnetic bearings 330 and 331, thus reducing the pressure losses caused by cooling. For example, the cooling fluid is supplied to the housing 340 and is arranged to circulate in the gap defined between the rotating magnetic assembly 322 and the stationary magnetic assembly 323. However, the stationary magnetic assembly 323 and / or the rotating magnetic assembly 322 can also be cooled by the cooling fluid according to other suitable circulation configurations. For example, the rotating magnetic component 322 and (possibly also at least partially related to) the fixed magnetic component 323 can be cooled by a first cooling fluid circulating in a gap defined between the rotating magnetic component 322 and the fixed magnetic component 323, and the fixed magnetic component 323 can also be cooled by a second cooling fluid, which can, for example, circulate inside the fixed magnetic component 323.

[0032] Advantageously, the expansion generator 300 further comprises at least one dry gas seal 341. Figure 3 In the example shown, the expansion generator 300 has two dry gas seals 341 and 342: the first dry gas seal 341 can be located at the first end of the fixed magnetic assembly 323 and the rotating magnetic assembly 322, in particular, between the first end and the magnetic bearings 330 and 331; and the second dry gas seal can be located at the second end of the fixed magnetic assembly 323 and the rotating magnetic assembly 322. Figure 3 In a variation of the example shown, the dry gas seal 342 is omitted. According to other possibilities, the dry gas seal 341 can be located in other locations. Advantageously, the dry gas seal 341 helps to isolate the impeller 310 and the generator 320, in particular to isolate the fluid expanded by the impeller (which is also used to cool the magnetic bearings) and the cooling fluid (which is used to cool the stationary magnetic assembly and / or the rotating magnetic assembly). Advantageously, the dry gas seal 342 helps to isolate the generator 320 from the environment surrounding the machine, in particular from the environment surrounding the housing 340.

[0033] According to one possibility, the cooling fluid is different from the fluid expanded by the impeller (i.e. hydrogen), for example air or water. According to another possibility, the cooling fluid is hydrogen, for example hydrogen fed to the machine inlet or hydrogen at a lower pressure relative to the machine inlet, in particular hydrogen from the machine outlet.

[0034] The following will use Figure 4 A fourth embodiment 400 of an expansion generator is described. Note that Figure 4 The elements 410, 411, 412, 413, 414, 420, 421, 422, 423, 430 and 440 in Figure 1 Elements 110 (impeller), 111 (machine inlet), 112 (machine outlet), 113 (fluid conduit), 114 (internal passage), 120 (generator), 121 (rotating hub), 122 (rotating magnetic assembly), 123 (stationary magnetic assembly), 130 (magnetic bearing) and 140 (housing) are the same or similar and perform the same or similar functions.

[0035] according to Figure 4 In the embodiment of the invention, the expansion generator 400 has three magnetic bearings, in particular, a first radial magnetic bearing 430, a thrust magnetic bearing 431 located downstream of the radial magnetic bearing 430 (note that the positions may also be swapped), and a second radial magnetic bearing 342. Some (advantageously, all) of the magnetic bearings 430, 431, and 432 may be cooled by the hydrogen gas flow from the machine inlet 411, in particular, they may be cooled in series and / or in parallel, as will be better described below.

[0036] Non-restrictive reference Figure 4 , a first part of the hydrogen fed to the machine inlet 411 is supplied, for example, first to the radial magnetic bearings 430 and then to the thrust magnetic bearings 431 to cool them, in particular flowing at least in the gaps between the rotating elements and the stator elements of the magnetic bearings 430 and 431 (see Figure 4 ), and finally the heated hydrogen is discharged to the machine outlet 412 (see the black arrow starting from the downstream of the thrust magnetic bearing 431 and ending at the machine outlet 412). In other words, the magnetic bearings 430 and 431 are cooled in series.

[0037] Non-restrictive reference Figure 4 , the second part of the hydrogen fed to the machine inlet 411 is for example first supplied to the radial magnetic bearing 432 and then to the generator 420, in particular circulating in the gap between the rotating magnetic assembly 422 and the fixed magnetic assembly 423. In other words, the magnetic bearing 432 and the generator 420 are cooled in series. According to another possibility not shown in the figure, the second part of the hydrogen fed to the machine inlet 411 is supplied only to the generator 420 to cool it.

[0038] Advantageously, the heated hydrogen downstream of the thrust magnetic bearing 431 and the heated hydrogen downstream of the generator 420 (ie after circulating in the gap between the rotating magnetic assembly 422 and the stationary magnetic assembly 423 ) is discharged to the machine outlet 412 .

[0039] Please note that according to Figure 4In the example shown, magnetic bearings 430, 431, magnetic bearing 432 and generator 420 are cooled in parallel. However, different configurations may be applied (see, for example, Figure 5 ). For example, the magnetic bearings and the generator may be cooled in series, with hydrogen being supplied first to at least one magnetic bearing and then to the generator, or first to the generator and then to at least one magnetic bearing.

[0040] exist Figure 5 It is shown in Figure 4 Another embodiment is similar to the embodiment of the present invention, but the difference is that the first part and the second part of the hydrogen gas used to cool the magnetic bearings 530, 531 and 532 and the generator 520 are the same hydrogen gas flow. In particular, non-limiting reference is made to Figure 5 , a portion of the hydrogen fed to the machine inlet 511 flows through the fluid conduit 513 and is used to cool in series: the first radial magnetic bearing 530, the thrust magnetic bearing 531, the generator 520 and the second radial magnetic bearing 532. Finally, the hydrogen portion downstream of the second radial magnetic bearing 532 is discharged at the machine outlet 512 as heated hydrogen and is preferably mixed with the expanded hydrogen expanded by the impeller 510.

[0041] According to another possibility (not shown in any of the figures), the thrust magnetic bearing 531 may be located downstream of the generator 520 and cooled by a portion of the hydrogen fed to the machine inlet 511, which portion of the hydrogen flows through the fluid duct 513 and is used to cool in series: the first radial magnetic bearing 530, the generator 520, the thrust magnetic bearing 531 and finally the second radial magnetic bearing 532. According to another possibility (not shown in any of the figures), the thrust magnetic bearing 531 may be located downstream of the second radial magnetic bearing 532 and cooled by a portion of the hydrogen fed to the machine inlet 511, which portion of the hydrogen flows through the fluid duct 513 and is used to cool in series: the first radial magnetic bearing 530, the generator 520, the second radial magnetic bearing 532 and finally the thrust magnetic bearing 531.

[0042] The following will use Figure 6 A sixth embodiment 600 of an expansion generator is described. Note that Figure 6 The elements 610, 611, 612, 613, 614, 620, 621, 622, 623, 630 and 640 in Figure 1 The elements 110 (impeller), 111 (machine inlet), 112 (machine outlet), 113 (fluid conduit), 114 (internal passage), 120 (generator), 121 (rotating hub), 122 (rotating magnetic assembly), 123 (stationary magnetic assembly), 130 (magnetic bearing), and 140 (housing) are the same or similar and perform the same or similar functions. Note that Figure 6 An implementation similar to Figure 4 implementation plan; Figure 6 and Figure 4 The only difference between the two is that a second portion of the hydrogen gas used for cooling the radial magnetic bearings 632 and the generator 620 is supplied by the machine outlet 612, as will become apparent hereinafter.

[0043] Non-restrictive reference Figure 6 , a portion of the hydrogen fed to the machine inlet 611 is supplied, for example, first to the radial magnetic bearings 630 and then to the thrust magnetic bearings 631 to cool them, in particular flowing at least in the gaps between the rotating elements and the stator elements of the magnetic bearings 630 and 631 (see Figure 6 ), and finally the heated hydrogen is discharged to the machine outlet 612 (see the black arrow starting from the downstream of the thrust magnetic bearing 631 and ending at the machine outlet 612). In other words, the magnetic bearings 630 and 631 are cooled in series.

[0044] Non-restrictive reference Figure 6 , the radial magnetic bearing 632 and the generator 620 can be cooled by a portion of the hydrogen supplied by the machine outlet 612, in particular by a portion of the hydrogen exhausted by the impeller 610. Advantageously, the machine 600 is provided with a control valve 680 located at the machine outlet 612 so as to allow the extraction of hydrogen from the machine outlet 612. In practice, the control valve 680 causes a pressure drop, in particular a small pressure drop ranging from 1 bar to 1.5 bar, to allow the circulation of hydrogen, as will be better described below.

[0045] according to Figure 6 In the embodiment of the invention, a portion of the hydrogen from the machine outlet 612 is, for example, first supplied to the radial magnetic bearing 632 and then supplied to the generator 620, in particular circulating in the gap between the rotating magnetic assembly 622 and the stationary magnetic assembly 623. In other words, the magnetic bearing 632 and the generator 620 are cooled in series.

[0046] Advantageously, heated hydrogen downstream of the thrust magnetic bearing 631 and heated hydrogen downstream of the generator 620 (ie after circulating in the gap between the rotating magnetic assembly 622 and the stationary magnetic assembly 623 ) can be combined and discharged to the machine outlet 612 , in particular downstream of the control valve 680 .

[0047] According to another possibility (not shown in any of the figures), the magnetic bearing 632 and the generator 620 can be cooled in parallel. In other words, the portion of hydrogen from the machine outlet 612 can be supplied between the generator 620 and the rotating magnetic assembly 622, so that a first portion of the hydrogen can flow through the gap between the rotating magnetic assembly 622 and the fixed magnetic assembly 623 in order to cool the generator 620, and a second portion of the hydrogen can flow through the gap between the rotating element and the stator element of the radial magnetic bearing 632 in order to cool the radial magnetic bearing 632. Advantageously, after cooling the generator 620 (i.e. downstream of the generator 620), the first portion of the hydrogen can be merged into the heated hydrogen downstream of the thrust magnetic bearing 631 and discharged to the machine outlet 612, in particular downstream of the control valve 680. Advantageously, after cooling the radial magnetic bearing 632 (i.e. downstream of the radial magnetic bearing 632), the second portion of the hydrogen can be merged into the heated hydrogen downstream of the thrust magnetic bearing 631 and discharged to the machine outlet 612, in particular downstream of the control valve 680.

[0048] Note that for clarity, Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 In the embodiment, the hydrogen flow for cooling the radial magnetic bearings and / or the thrust magnetic bearings and / or the generator is shown outside the casing of the machine. However, the casing of the machine may be provided with suitable channels so that the hydrogen flow circulates inside the casing.

[0049] According to some embodiments (not shown in the drawings), the expansion generator (e.g., the machines 100, 200, 300, 400, 500, and 600 in the drawings) may include a second impeller. It should be noted that the second impeller may be an expander or a compressor that expands or compresses the hydrogen supplied to the machine, respectively. In particular, the second impeller may be located at the same end of the expansion generator as the first impeller 110, 210, 310, 410, 510, and 610 (i.e., located at the same rotating hub end), or may be located at the opposite end relative to the first impeller 110, 210, 310, 410, 510, and 610 (i.e., located at the opposite rotating hub end). The hydrogen supply from the machine inlet 112, 212, 312, 412, 512, and 612 to the first impeller and the second impeller may be in series or in parallel. According to an advantageous possibility, the thrust magnetic bearing can be omitted if the second impeller of the expansion generator is located at the opposite rotating hub end relative to the first impeller and the hydrogen supply to the first and second impellers is parallel.

[0050] In summary, the expansion generators 100, 200, 300, 400, 500 and 600 can utilize one or more portions of the fluid expanded by the impeller to cool at least one magnetic bearing of the machine and advantageously also cool the generator. Preferably, the expansion generators 100, 200, 300, 400, 500 and 600 are arranged so that during operation of the machine, the ambient pressure inside the housing is higher than the ambient pressure outside the housing; in other words, the housing is pressurized so that the surrounding environment does not leak into the housing. Even more preferably, during installation or prior to start-up of the machines 100, 200, 300, 400, 500 and 600, the environment inside the housing is evacuated of oxygen to avoid the risk of fire and / or explosion.

Claims

1. An expansion generator (100) having a machine inlet (111) and a machine outlet (112) and comprising: an impeller (110) configured to receive compressed hydrogen from the machine inlet (111), expand the compressed hydrogen through impeller blades and discharge the expanded hydrogen at the machine outlet (112), a generator (120) configured to generate electrical energy and comprising a rotating hub (121), a rotating magnetic assembly (122) mechanically coupled to the rotating hub (121), and a fixed magnetic assembly (123) arranged around the rotating magnetic assembly (122), - at least one magnetic bearing (130) acting on the rotating hub (121), - a housing (140) containing the impeller (110), the generator (120) and the at least one magnetic bearing (130), wherein the impeller (110) is mechanically connected to the rotating hub (121), wherein the at least one magnetic bearing (130) is fluidly coupled to the inlet (111), and The machine is configured to be cooled by a flow of hydrogen gas from the machine inlet (111).

2. The expansion generator (100, 200, 300, 400, 500) according to claim 1, wherein at least one magnetic bearing (130, 230, 330, 430, 530) is located between the impeller (110, 210, 310, 410, 510) and the generator (120, 220, 320, 420, 520).

3. The expansion generator (100, 200, 300, 400, 500) according to claim 1 is arranged so that during operation of the machine, the ambient pressure inside the housing (140, 240, 340, 440, 540) is higher than the ambient pressure outside the housing.

4. The expansion generator (100, 200, 300, 400, 500) according to claim 1, wherein the expansion generator is arranged so that the environment inside the housing (140, 240, 340, 440, 540) is oxygen-free.

5. The expansion generator (200, 300, 400, 500) of claim 1, wherein the at least one magnetic bearing (230, 330, 331, 430, 431, 432, 530, 531, 532) is fluidly coupled to the machine outlet (212, 312, 412, 512) and is configured to discharge a heated hydrogen gas stream at the outlet (212, 312, 412, 512).

6. The expansion generator (100, 200, 300, 400, 500) according to claim 1, further comprising a fluid conduit (113, 213, 313, 413, 513) fluidly coupling the machine inlet (111, 211, 311, 411, 511) and the at least one magnetic bearing (130, 230, 330, 430, 530), wherein the fluid conduit (113, 213, 313, 413, 513) is at least partially defined by a rear surface of the impeller (110, 210, 310, 410, 510).

7. The expansion generator (100, 200, 300, 400, 500) according to claim 6, wherein the impeller (110, 210, 310, 410, 510) includes at least one internal channel (114, 214, 314, 414, 514) fluidly connecting the fluid conduit (113, 213, 313, 413, 513) and the impeller blades.

8. The expansion generator (300, 400, 500) according to claim 1, further comprising a cooling system, wherein the cooling system is configured to circulate a cooling fluid to cool the rotating magnetic assembly (322, 422, 522) and / or the fixed magnetic assembly (323, 423, 523).

9. The expansion generator (300, 400, 500) of claim 8, wherein a gap is defined between the rotating magnetic assembly (322, 422, 522) and the fixed magnetic assembly (323, 423, 523), and Wherein the cooling fluid is arranged to circulate in the gap.

10. The expansion generator (300, 400) according to claim 8, comprising a first cooling system and a second cooling system, wherein the first cooling system is configured to circulate a first cooling fluid to cool the rotating magnetic component (322, 422) and possibly also cool the fixed magnetic component (323, 423), and the second cooling system is configured to circulate a second cooling fluid to cool the fixed magnetic component (323, 423).

11. The expander generator (400, 500) of claim 8, wherein the cooling fluid is hydrogen.

12. The expander generator (400) according to claim 10, wherein the first cooling fluid and the second cooling fluid are both hydrogen.

13. The expander-generator (400, 500) of claim 8, wherein the cooling system is fluidly coupled to the inlet (411, 511) and is configured to circulate a flow of hydrogen gas from the machine inlet (411, 511).

14. The expander-generator (400, 500) of claim 8, wherein the cooling system is fluidly coupled to the machine outlet (412, 512) and is configured to discharge a heated hydrogen gas stream at the machine outlet (412, 512).

15. The expansion generator (400, 500) of claim 14, wherein the cooling system is fluidly coupled to the at least one magnetic bearing (432, 530, 531, 532).

16. The expander generator (400) of claim 14, configured to discharge the heated hydrogen gas flow from the gap and the heated hydrogen gas flow from the at least one magnetic bearing (430, 431, 432) to the machine outlet (412).

17. The expansion generator (400, 500) according to claim 1, wherein the at least one magnetic bearing is a first radial magnetic bearing (430, 530), a thrust magnetic bearing (431, 531) and a second radial magnetic bearing (432, 532).

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