Cryogenic refrigeration installation and process

Abstract

The invention relates to a cryogenic refrigeration installation comprising an enclosure housing at least two thermally conductive trays (4, 5, 6, 7) forming thermal stages, the installation (1) comprising a cryogenic temperature cooling system for the trays (4, 5, 6, 7) and / or one or more plates (24, 25, 26) connected (30) to the trays (4, 5, 6, 7), the cooling system comprising a refrigerator (70) with a cycle refrigeration system for a cycle fluid and a cycle circuit (8) comprising a first storage pot (17) for a reserve of liquefied cycle fluid, the cycle circuit (8) comprising a bypass line (18) for diverting at least a portion of the cycle fluid flow to the first storage pot (17), the bypass line (18) comprising an expansion device (19) configured to expand the cycle gas before feeding the first storage pot (17), the cycle circuit (8) includes,upstream of the heat exchange with at least part of the trays (4, 5, 6) and / or plates (24, 25, 26), a portion exchanges heat with the liquefied cycle fluid contained in the first storage pot (17). Abbreviated figure: Fig. 1,

Description

Title of the invention: Cryogenic refrigeration installation and method

[0001] The invention relates to a cryogenic refrigeration installation and method.

[0002] The invention relates more particularly to a refrigeration installation cryogenic comprising an enclosure delimiting a sealed volume closed by a cover, the enclosure housing at least two thermally conductive trays distributed according to a distribution direction in the enclosure and forming thermal stages, at least one of the trays being connected to a thermal shield forming a thermal insulation volume, the installation comprising a cryogenic temperature cooling system configured to cool at least part of the trays and / or one or more plates connected to the trays and forming a support for a set of cable(s) or samples to be cooled, the cryogenic temperature cooling system comprising a refrigerator with a cycle fluid refrigeration cycle, said refrigerator comprising a cycle circuit containing a cycle fluid comprising helium,the cycle circuit being configured to subject the cycle fluid to a thermodynamic cycle bringing the cycle fluid to at least one cold end of the cycle circuit at a determined cold temperature, the cycle circuit putting into heat exchange a flow of cycle fluid from the cold end with at least part of the plates and / or trays, the cycle circuit comprising a mechanism for compressing the cycle fluid, at least one member for cooling the cycle fluid, a mechanism for expanding the cycle fluid and at least one member for heating the expanded cycle fluid.

[0003] In particular, the invention relates to refrigeration devices which make it possible to cool to very low temperatures, of the order of millikelvin ("subKelvin refrigeration"). These very low temperatures are conventionally obtained via a dilution refrigerator or a Joule Thomson type cryogenic cooler using He4 or He3.

[0004] In these devices, it is necessary to provide cooling power up to a temperature of, for example, 4K to one or more refrigeration stages. An installation of this type must be able to be cooled quickly when it is started up. In addition, the experimental surface available for the samples or cables to be cooled must be optimized.

[0005] Dilution refrigerators require a supply of cooling power up to a temperature of 4.2K or less to operate. This cooling power is generally supplied from pulsed gas tubes ("dry" dilution refrigerators), either via a liquid helium bath (“wet” dilution refrigerators). In “Qbits” applications, the cooling power must be increased.

[0006] Increasing the number of pulsed gas tubes limits the experimental surface area available for integrating Qbits. In addition, this solution does not provide very high cooling power to cool a set of cable(s) or samples and to pre-cool the working fluid of the dilution stage. In addition, this solution generates vibrations.

[0007] An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

[0008] To this end, the installation according to the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that the cycle circuit comprises a first storage pot for a reserve of liquefied cycle fluid, the cycle circuit comprising, downstream of the heat exchange with at least a portion of trays and / or plates, a bypass pipe for at least a portion of the cycle fluid flow to the first storage pot, the bypass pipe comprising a member for expanding the cycle gas flow configured to expand the cycle gas before supplying the first storage pot, and in that the cycle circuit comprises, upstream of the heat exchange with at least a portion of trays and / or plates, a portion in heat exchange with the liquefied cycle fluid contained in the first storage pot.

[0009] Furthermore, embodiments of the invention may include one or more of the following features: - the heat exchange portion between the liquefied cycle fluid contained in the pot and the cycle fluid of the cycle circuit comprises a passage from the cycle circuit into the liquefied cycle fluid inside the first storage pot, - the heat exchange portion between the liquefied cycle fluid contained in the pot and the cycle fluid of the cycle circuit comprises a passage from the cycle circuit into an exchanger cooled by a liquefied cycle fluid circulation loop supplied by the first storage pot, for example a thermosiphon, - the cycle circuit comprises, downstream of the heat exchange with at least a portion of trays and / or plates, a return pipe which is configured to return to the compression mechanism the fraction of the cycle fluid flow which has not been diverted to the first storage pot, - the cycle circuit includes a return line connecting a first storage pot outlet to the compression mechanism, - the return line includes a cryogenic pump or compressor, - the cycle circuit comprises a second storage pot for a reserve of liquefied cycle fluid connected to the return pipe and / or the bypass pipe (18), - the cycle circuit is configured to store in the second storage pot a reserve of liquefied cycle fluid having a determined temperature higher than the determined temperature of the cycle fluid stored in the first storage pot, - the cycle circuit comprises a conduit connecting the second storage pot to the first storage pot and configured to allow the transfer of liquefied cycle fluid from the second storage pot to the first storage pot, - the refrigerator cycle circuit comprises several separate pipes exchanging heat between different cycle fluid flows with separate trays and / or plates, - the cycle circuit comprises at least one pipe carrying out heat exchange of the cycle fluid in series with several separate trays and / or plates of the same enclosure and / or several separate enclosures, - the cycle circuit is configured to subject the cycle fluid to a thermodynamic cycle bringing the cycle fluid to several separate cold temperatures at the level of several cold ends of the cycle circuit, the cycle circuit of the refrigerator comprising several separate pipes carrying out heat exchange in parallel between different flows of cycle fluid at different temperatures with respective separate trays and / or plates.

[0010] The invention also relates to a refrigeration method using an installation conforming to any one of the characteristics above or below, the method comprising a step of producing a cold power determined by the refrigerator, a use of a portion of this cold power produced to cool a set of tray(s) and / or plate(s) by heat exchange with a cycle fluid flow, a step of recovering this cycle fluid flow after heat exchange and a step of expanding a fraction of this recovered cycle fluid flow towards the first storage pot to constitute a cold reserve, the method comprising a step of cooling the cycle fluid flow with the cycle fluid of the first storage pot.

[0011] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

[0012] Other features and advantages will appear on reading the description below, given with reference to the figures in which: Brief description of the figures

[0013] The invention will be better understood on reading the following description given solely by way of example and with reference to the appended drawings in which:

[0014] [Fig. 1] is a schematic and partial view illustrating an example of structure and operation of an installation according to a first embodiment of the invention,

[0015] [Fig.2] is a schematic and partial view illustrating an example of structure and operation of an installation according to a second embodiment of the invention;

[0016] [Fig.3] is a schematic and partial view illustrating an example of structure and operation of an installation according to a third embodiment of the invention. Detailed description

[0017] In all the figures, the same references refer to the same elements.

[0018] In this detailed description, the following embodiments are examples. Well that the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Single features of different embodiments may also be combined and / or interchanged to provide other embodiments.

[0019] The cryogenic refrigeration installation 1 illustrated in [Fig.l] comprises an enclosure 2 delimiting a sealed volume closed by a cover 3. The enclosure 2 houses in this example three thermal conductive plates 4, 5, 6 distributed according to a distribution direction in the enclosure 2 (here vertical) and forming thermal stages. The plates 4, 5, 6 are preferably each connected to a respective thermal screen 14, 15, 16 forming a thermal insulation volume. For example, according to the distribution direction each thermal screen encompasses (houses) the following thermal screen and plate (in a “nested” manner).

[0020] The installation 1 comprises a cryogenic temperature cooling system configured to cool at least a portion of the trays 4, 5, 6 and / or one or more support plates 24, 25, 26 which can be connected (30) to the trays 4, 5, 6. These support plates 24, 25, 26 can be mounted in a removable or detachable manner on the trays 4, 5, 6 concerned to form a support for a set of cable(s) or samples to be cooled (not shown for the sake of simplification).

[0021] The cryogenic temperature cooling system comprises a refrigerator 70 with a cycle fluid refrigeration cycle.

[0022] The refrigerator 70 comprises a cycle circuit 8 containing a cycle fluid comprising helium. The cycle fluid could be composed of other gas(es), for example for example a mixture comprising helium and at least one of: hydrogen, nitrogen, neon, one or more hydrocarbons.

[0023] The cycle circuit 8 is configured to subject the cycle fluid to a thermodynamic cycle bringing the cycle fluid to at least one cold end of the cycle circuit 8 at a determined cold temperature.

[0024] The cycle circuit 8 comprises a mechanism 9 for compressing the cycle fluid (one or more compressors in series and / or in parallel), at least one member 11, 12, 13, 14 for cooling the cycle fluid (for example one or more heat exchangers), a mechanism 10, 15 for expanding the cycle fluid (one or more valve(s) and / or turbine(s) in series and / or in parallel) and at least one member 14, 13, 12, 11 for heating the expanded cycle fluid (one or more heat exchangers). As illustrated, the cooling and heating of the cycle fluid can be ensured by one or more heat exchangers ensuring a heat exchange between two flows of cycle fluid at different temperatures (for example counter-current).

[0025] A part of the cycle circuit 8 and in particular the relatively hot portions can be located outside the enclosure 2.

[0026] The cycle circuit 8 has pipes putting at least one flow of cycle fluid from the cold end into heat exchange with at least a portion of the plates 4, 5, 6 and / or plates 24, 25, 26. For example, pipes transfer the cold cycle fluid into heat exchangers 34, 35, 36 in contact with the plates and / or plates. Alternatively or cumulatively, the pipes carrying the cycle circuit 8 may have portions in direct contact (and / or in the thickness) of the plates 4, 5, 6 and / or plates, 24, 25, 26 and / or heat shield.

[0027] For example, the cycle circuit 8 of the refrigerator 70 comprises several separate conduits 108, 208 putting into heat exchange different flows of cycle fluid with trays 4, 5, 6 and / or plates 24, 25, 26 separate from the same enclosure 2 (see [Fig.1]) or from several separate enclosures 2 (see [Fig.2] or [Fig.3]).

[0028] For example, the cycle circuit 8 may be configured to subject the cycle fluid to a thermodynamic cycle bringing the cycle fluid to several distinct cold temperatures at respectively several cold ends of the cycle circuit and the cycle circuit 8 of the refrigerator 70 comprising several distinct conduits 108, 208 putting into parallel heat exchange different flows of cycle fluid at different temperatures with respective distinct trays 4, 5, 6 and / or plates 24, 25, 26.

[0029] This makes it possible to produce and send supercritical cycle fluid under pressure (for example at a pressure greater than 3.5 bar) to one or more stages of one or more enclosures 2, for example in parallel.

[0030] The supercritical fluid can be produced in the cycle circuit 8 by an arrangement exchangers, in order to best recover the available cold power.

[0031] Thus, the cycle circuit 8 can supply cycle fluid at intermediate temperatures, for example between 4K and 100K, to cool intermediate stages in one or more enclosures 2.

[0032] This allows independent operations for different enclosures 2 with the same common refrigeration system 70.

[0033] This solution makes it possible to provide a cold power which can be easily adapted.

[0034] For this purpose, the various pipes supplying the various stages or enclosures 2 may be provided with flow control valves. These valves may be regulated as a function of the temperature of the element to be cooled (expected cold power). The cycle fluid flow rates may be regulated to increase or decrease the demand for cold power in the enclosure 2.

[0035] The cycle circuit 8 comprises a first pot 17 for storing a reserve of liquefied cycle fluid.

[0036] The cycle circuit 8 comprises, downstream of the heat exchange with at least a portion of plates 4, 5, 6 and / or plates 24, 25, 26, a conduit 18 for diverting at least a portion of the cycle fluid flow to the first storage pot 17.

[0037] That is to say that the at least one pipe which returns to the heating members (exchangers 14, 13, 12, 11) and the compression members (compressor 9, 8) the cycle fluid which has exchanged heat with the elements to be cooled in the enclosure 2 has a bypass 18 towards the first storage pot 17. This bypass pipe 18 preferably has a member 19 for expanding the cycle gas flow (valve(s) or equivalent) configured to expand the cycle gas before supplying the first storage pot 17.

[0038] The installation 1 may be sized or the operating conditions may lead to the cooling in the enclosure 2 using only a portion of the power available in the cold cycle fluid flow. This cycle fluid returns relatively cold and the cold power which has not been used to cool the components in the enclosure 2 can be utilized.

[0039] This is achieved by expanding a portion of this cycle fluid to the first storage pot 17.

[0040] This arrangement makes it possible to optimize the cold power produced by minimizing the flow rate of low-pressure working fluid (gas coming from the first storage pot 17).

[0041] In addition, this makes it possible to maximize the flow rate of cold cycle fluid circulated in the enclosure(s) 2 (maximizes the available power).

[0042] The cycle fluid flow not used for this bypass can be returned to the cycle compressor of the refrigerator by giving up frigories to the cycle fluid in downstream of the compression. For this purpose, the cycle circuit 8 comprises, downstream of the heat exchange with at least a portion of plates 4, 5, 6 and / or plates 24, 25, 26, a return pipe 28 which is configured to return to the compression mechanism 9 the fraction of the cycle fluid flow which has not been diverted to the first storage pot 17.

[0043] This expanded fluid produces liquid at very low temperature (typically between 1K and 4K) which is put into heat exchange with the cycle fluid before its heat exchange with the components in enclosure 2.

[0044] That is to say that the cycle circuit 8 comprises, upstream of the heat exchange with at least a portion of plates 4, 5, 6 and / or plates 24, 25, 26, a portion in heat exchange with the liquefied cycle fluid contained in the first storage pot 17. The cold reserve constituted by the first storage pot 17 provides cold to the cycle fluid before its use to cool the element(s) in the enclosure 2.

[0045] In the example of [Fig.l], the heat exchange between the liquefied cycle fluid contained in the pot 17 and the cycle fluid of the cycle circuit 8 comprises a passage of the cycle circuit 8 into the liquefied cycle fluid inside the first storage pot 17. That is to say that a part of the cycle circuit 8 is immersed in the liquid bath of the first storage pot 17, for example by describing a coil or several passages or bends therein.

[0046] In the example of [Fig. 3], the heat exchange between the liquefied cycle fluid contained in the pot 17 and the cycle fluid of the cycle circuit 8 is carried out via a passage of the cycle circuit 8 in a heat exchanger 15 cooled by a liquefied cycle fluid circulation loop 47 supplied by the first storage pot 17, for example a thermosiphon. This constitutes a more indirect heat exchange than in the previous embodiment.

[0047] The cycle circuit 8 also preferably comprises a return pipe 38 connecting an outlet (for example upper) of the first storage pot 17 to the compression mechanism 9. This allows the vaporization gas to be returned to the compression within the first storage pot 17.

[0048] As illustrated in [Fig.3], the return line 38 may comprise a pump 10 or a cryogenic compressor.

[0049] As illustrated in [Fig.2] and [Fig.3], the cycle circuit 8 may comprise a second storage pot 27 for storing a reserve of liquefied cycle fluid. This second storage pot 27 is for example connected in parallel with the first storage pot 17 on the bypass pipe 18. The flow of fluid returning from the enclosure 2 via the return pipe 28 may be sent to the first storage pot 17 (via the valve 19) or to the second pot 27 (via the valve 128). A pipe and valve 127 may be provided for transferring liquid from the second storage pot 27 to the first pot 17. This valve 127 can be used to regulate the liquid level in the second pot 27. The gas formed in the second storage pot 27 is sent to the compressor 9.

[0050] This return pipe 28 can for example supply the second storage pot 27 at an intermediate level between its upper and lower ends. As illustrated, an upper outlet of this second storage pot 27 can be connected to the compression of the cycle circuit, for example at an intermediate pressure level between the low pressure at the inlet and the high pressure at the outlet (between two compressors 9 in series).

[0051] The second storage pot 27 may be configured to store a reserve of liquefied cycle fluid having a determined temperature (for example of the order of 4K) higher than the determined temperature of the cycle fluid stored in the first storage pot 17 (for example of the order of 2K).

[0052] As illustrated, preferably the cycle circuit 89 does not include a thermosiphon at the second storage pot 27 but of course a thermosiphon could be provided at the second storage pot 27. An exchanger 14 can be placed on the circuit 8 before the second storage pot 27 to take advantage of the low temperature of the return fluid. This makes it possible to improve the energy efficiency of the system.

[0053] All or part of the components of the refrigerator and / or the enclosure 2 may be housed in a thermally insulated cold box, for example under vacuum. The operation may be at least partly automated, which limits the handling of cryogenic fluid by the user.

[0054] The structure of the installation 1 allows cold power along a capillary in the enclosure, unlike more punctual cooling of known solutions with cryogenic liquid bath.

[0055] The above structure is more efficient and flexible than solutions that exclusively use pulsed gas tubes to cool stages of the enclosures 2.

[0056] This type of installation requires less maintenance than prior art solutions.

[0057] In addition, this solution offers higher cooling power (and lower available cold temperature) which can be used to reduce the pre-cooling / cooling time of the installation at start-up. In particular, such an installation can provide a very cold cycle fluid flow, for example at a temperature of the order of 1K.

[0058] Such an installation can be advantageously used to cool Qbits in quantum computing centers.

[0059] The installation can use one or more cryogenic compressors in the cycle circuit 8 for better recovery of calories in the cycle exchangers.

[0060] The draining of the cycle fluid in the enclosure(s) can be carried out quickly, which significantly reduces the heating time of the installation during a shutdown (compared to a conventional “wet” solution).

Claims

1. Claims Cryogenic refrigeration installation comprising an enclosure (2) delimiting a sealed volume closed by a cover (3), the enclosure (2) housing at least two thermally conductive trays (4, 5, 6, 7) distributed in a distribution direction in the enclosure (2) and forming thermal stages, at least one of the trays (4, 5, 6, 7) being connected to a thermal screen (14, 15, 16) forming a thermal insulation volume, the installation (1) comprising a cryogenic temperature cooling system configured to cool at least a portion of the trays (4, 5, 6, 7) and / or one or more plates (24, 25, 26) connected (30) to the trays (4, 5, 6, 7) and forming a support for a set of cable(s) (30) or samples to be cooled, the cryogenic temperature cooling system comprising a refrigerator (70) with a refrigeration cycle of a cycle fluid,said refrigerator (70) comprising a cycle circuit (8) containing a cycle fluid comprising helium, the cycle circuit (8) being configured to subject the cycle fluid to a thermodynamic cycle bringing the cycle fluid to at least one cold end of the cycle circuit (8) at a determined cold temperature, the cycle circuit putting into heat exchange a flow of cycle fluid from the cold end with at least a portion of the plates (4, 5, 6, 7) and / or plates (24, 25, 26), the cycle circuit (8) comprising a mechanism (9) for compressing the cycle fluid, at least one member (11, 12, 13, 14) for cooling the cycle fluid, a mechanism (10, 15) for expanding the cycle fluid and at least one member (14, 13, 12, 11) for heating the expanded cycle fluid, characterized in that the cycle circuit (8) comprises a first pot (17) of storage of a reserve of liquefied cycle fluid, the cycle circuit (8) comprising,downstream of the heat exchange with at least a portion of trays (4, 5, 6) and / or plates (24, 25, 26), a conduit (18) for diverting at least a portion of the cycle fluid flow to the first storage pot (17), the diverting conduit (18) comprising a member (19) for expanding the cycle gas flow configured to expand the cycle gas before supplying the first storage pot (17) and in that the cycle circuit (8) comprises, upstream of the heat exchange with at least a portion of trays (4, 5, 6) and / or plates (24, 25, 26), a portion in heat exchange with the liquefied cycle fluid contained in the first storage pot (17).,

2. Installation according to claim 1 characterized in that the heat exchange portion between the liquefied cycle fluid contained in the pot (17) and the cycle fluid of the cycle circuit (8) comprises a passage from the cycle circuit (8) into the liquefied cycle fluid inside the first storage pot (17).

3. Installation according to claim 1 or 2 characterized in that the heat exchange portion between the liquefied cycle fluid contained in the pot (17) and the cycle fluid of the cycle circuit (8) comprises a passage of the cycle circuit (8) in an exchanger (15) cooled by a loop (47) for circulating liquefied cycle fluid supplied by the first storage pot (17), for example a thermosiphon.

4. Installation according to any one of claims 1 to 3 characterized in that the cycle circuit (8) comprises, downstream of the heat exchange with at least a portion of plates (4, 5, 6) and / or plates (24, 25, 26), a return pipe (28) which is configured to return to the compression mechanism (9) the fraction of the cycle fluid flow which has not been diverted to the first storage pot (17).

5. Installation according to any one of claims 1 to 4, characterized in that the cycle circuit (8) comprises a return pipe (38) connecting a first storage pot outlet (17) to the compression mechanism (9).

6. Installation according to claim 5, characterized in that the return pipe (38) comprises a pump (10) or a cryogenic compressor.

7. Installation according to any one of claims 1 to 6, characterized in that the cycle circuit (8) comprises a second pot (27) for storing a reserve of liquefied cycle fluid connected to the return pipe (28) and / or the bypass pipe (18).

8. Installation according to claim 7, characterized in that the cycle circuit (8) is configured to store in the second storage pot (27) a reserve of liquefied cycle fluid having a determined temperature higher than the determined temperature of the cycle fluid stored in the first storage pot (17).

9. Installation according to claim 7 or 8, characterized in that the cycle circuit (8) comprises a pipe connecting the second storage pot (27) to the first storage pot (17) and configured to allow the transfer of liquefied cycle fluid from the second storage pot (27) to the first storage pot (17).

10. Installation according to any one of claims 1 to 9, characterized in that the cycle circuit (8) of the refrigerator (70) comprises several separate pipes (108, 208) putting into heat exchange different flows of cycle fluid with separate plates (4, 5, 6) and / or plates (24, 25, 26).

11. Installation according to any one of claims 1 to 10, characterized in that the cycle circuit (8) comprises at least one pipe putting into heat exchange of the cycle fluid in series with several plates (4, 5, 6) and / or plates (24, 25, 26) distinct from the same enclosure (2) and / or or from several distinct enclosures (2).

12. Installation according to any one of claims 1 to 11, characterized in that the cycle circuit (8) is configured to subject the cycle fluid to a thermodynamic cycle bringing the cycle fluid to several distinct cold temperatures at respectively several cold ends of the cycle circuit, the cycle circuit (8) of the refrigerator (70) comprising several distinct conduits (108, 208) putting into parallel heat exchange different flows of cycle fluid at different temperatures with respective distinct trays (4, 5, 6) and / or plates (24, 25, 26).

13. A refrigeration method using an installation according to any one of the preceding claims, the method comprising a step of producing a cold power determined by the refrigerator (70), using a portion of this cold power produced to cool a set of tray(s) (4, 5, 6) and / or plate(s) (24, 25, 26) by heat exchange with a cycle fluid flow, a step of recovering this cycle fluid flow after heat exchange and a step of expanding a fraction of this recovered cycle fluid flow towards the first storage pot (17) to constitute a cold reserve, the method comprising a step of cooling the cycle fluid flow with the cycle fluid of the first storage pot (17).

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