Low-temperature refrigeration device

Abstract

The invention relates to a refrigeration device comprising a circuit for a working fluid and comprising a mechanism (3) for compressing the working fluid with at least one compressor, a mechanism (4, 7) for cooling the working fluid, a mechanism (6) for expanding the working fluid with at least one expansion turbine (6) and a mechanism (7) for heating the working fluid, the device comprising an insulated cold box (9) housing a heat exchanger (7) and the at least one turbine (6), the cold box (9) having a cylindrical shape extending in a longitudinal direction about a central axis (10), the at least one turbine (6) being arranged in the cold box (9) in a transversely offset manner with respect to its central longitudinal axis (10).

Description

Low temperature refrigeration device

[0001] The invention relates to a low temperature refrigeration device.

[0002] The invention relates more particularly to a low-temperature refrigeration and / or liquefaction device, i.e. at a temperature between minus 100 degrees centigrade and minus 273 degrees centigrade, the refrigeration device comprising a working circuit forming a loop and containing a working fluid, the working circuit comprising a working fluid compression mechanism comprising at least one compressor, a working fluid cooling mechanism, a working fluid expansion mechanism comprising at least one expansion turbine and a working fluid heating mechanism, the working circuit being configured to subject the working fluid to a determined thermodynamic cycle in which the working fluid reaches a relatively low temperature at a cold end of the cycle,the device comprising a refrigeration heat exchanger intended to extract heat from at least one member or fluid by heat exchange with the working fluid, the device comprising a thermally insulated cold box housing the refrigeration heat exchanger and the at least one expansion turbine, the cold box having a generally cylindrical shape extending in a longitudinal direction around a central axis, said axis preferably being horizontal in the use configuration, the at least one turbine being arranged in the cold box (9) near a first longitudinal end of the cold box, the at least one turbine being mounted longitudinally in the cold box between the refrigeration heat exchanger and the longitudinal end wall of the cold box.,

[0003] The invention relates in particular to cryogenic refrigerators or liquefiers comprising turbomachines using cryogenic turbines. These refrigerators also have inter-stage cooling and / or heating heat exchangers and a cryogenic enclosure called a cold box (and thermally insulated, for example under vacuum).

[0004] These refrigerators are mounted on a structure and a problem is to maximize the ratio between the system capacity (and therefore the number of components) and its dimensions in width and height. This optimization allows either to increase the system capacity while remaining within a fixed transport template, or to minimize the dimensions compared to a fixed capacity.

[0005] Another constraint is to achieve a reliable assembly that does not require welding at the refrigerator's destination site.

[0006] In a known embodiment, the turbines are mounted on the side of the cold box. This allows for the installation of a large number of turbines by decoupling the manufacturing of the turbines and the cold box. The heat exchangers are installed near the turbines, without any size limitation. However, this solution has the disadvantage that the turbines protrude beyond the transport gauge. The turbines are therefore transported separately and connected (welded) at the destination site. The exchangers are either mounted directly on the turbines or on a separate support. This solution requires additional time and assembly costs after manufacturing.

[0007] Another solution is to install equipment, particularly turbines, on top of the cold box. However, this solution is not suitable for high-power turbines, which require heat exchangers installed on a separate support. This requires the connection pipes to be installed on site.

[0008] Another solution is to mount a single turbine on the bottom of the cold box at the central axis of revolution. The turbine heat exchanger and the compressor heat exchanger can be combined into a single unit. In the case of a refrigerator producing very low temperatures, however, it is necessary to provide a staging of several turbines. The heat exchanger is installed next to the vacuum chamber, which degrades the capacity / dimensions ratio when there are several heat exchangers and / or if the diameter of the exchanger increases.

[0009] An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

[0010] To this end, the according to the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that the at least one turbine is mounted offset transversely relative to the central longitudinal axis of the cold box.

[0011] Furthermore, embodiments of the invention may include one or more of the following features:the at least one turbine is mounted at the end of a shaft of a motor also driving a compressor of the compression mechanism, the motor being located outside the cold box, the end of the shaft carrying the turbine being mounted through-sealed through the end wall of the cold box,the end of the shaft carrying the turbine is mounted through-sealed through the end wall of the cold box via a tubular tapping connection mounted projecting from the outer surface of the longitudinal end wall of the cold box,the longitudinal end wall of the cold box has a shape bulging towards the outside of the cold box,the device comprises at least one additional turbine arranged in the cold box near a second longitudinal end of the cold box,the at least one additional turbine being mounted longitudinally in the cold box between the refrigeration heat exchanger and the end wall of the second longitudinal end of the cold box, offset transversely relative to the central longitudinal axis of the cold box, the device is arranged in and / or on a support, the working circuit comprises at least one heat exchanger located outside the cold box forming part of the working fluid cooling mechanism, said at least one heat exchanger being mounted in and / or on the support in a plane perpendicular to the longitudinal direction, the device comprises several heat exchangers located outside the cold box forming part of the working fluid cooling mechanism, said heat exchangers being mounted in and / or on the support in respective planes perpendicular to the longitudinal direction,the support comprises at least one of: a set of support feet of the cold box, a frame, the support is composed of several structures assembled in the longitudinal direction.,

[0012] 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.

[0013] Other features and advantages will appear on reading the description below, made with reference to the figures in which: Brief description of the figures

[0014] 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:

[0015] is a schematic, partial and top view of a refrigeration device according to a first exemplary embodiment,

[0016] is a schematic, partial and side view of the device of the;

[0017] a simplified schematic view of a detail of the device symbolizing the working circuit,

[0018] is a schematic, simplified and partial view, in perspective and from above, of a refrigeration device according to another exemplary embodiment. Detailed description

[0019] In all figures, the same references refer to the same elements.

[0020] In this detailed description, the following embodiments are examples. Although 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 within the scope of the claims.

[0021] The illustrated low temperature refrigeration device 1 is for example a cryogenic refrigerator, i.e. producing cold power by cooling / liquefying a working fluid to a temperature between minus 100 degrees centigrade and minus 273 degrees centigrade.

[0022] The refrigeration device 1 is preferably at least partly arranged (mounted) in and / or on a rigid support 100.

[0023] The refrigeration device 1 comprises a working circuit 2 forming a loop and containing a working fluid (for example at least one of: helium, nitrogen, argon, neon, hydrogen). As also illustrated in the, the working circuit 2 comprises, arranged in series, a mechanism 3 for compressing the working fluid comprising at least one compressor, a mechanism 4, 7 for cooling the working fluid (heat exchanger(s) for example), a mechanism for expanding the working fluid comprising at least one expansion turbine 6 and a mechanism 7 for heating the working fluid. The working circuit 2 is configured to subject the working fluid to a determined thermodynamic cycle in which the working fluid reaches at least one relatively low temperature at a cold end of the cycle.

[0024] The compressors 3 are preferably driven in rotation by one or more electric motors 13 (for example mounted on the rotary shaft 12 of the motor 13). Preferably, at least a portion of the turbines 6 is also coupled to the same rotary shaft 12 driving one or more compressors 3 to provide it with mechanical work (motor-turbo-compressor).

[0025] The device 1 comprises one or more refrigeration heat exchangers 7 intended to extract heat from at least one member 8 or fluid by heat exchange with the working fluid at the cold end of the cycle. As illustrated, the refrigeration heat exchanger 7 can provide heat exchange between the working fluid after its expansion in the working circuit (before its return to the compression mechanism) and a user fluid 8 to be cooled. The exchanger(s) 7 can provide both cooling and heating of the working fluid in the cycle via a countercurrent exchange.

[0026] Typically, a fluid 8 to be cooled may be placed in heat exchange with the working fluid at several temperature levels between ambient temperature and the coldest temperature of the cold end of the cycle.

[0027] The expansion mechanism comprises at least one expansion turbine 6 and preferably several expansion turbines 6.

[0028] The device 1 comprises a cold box 9, that is to say a thermally insulated enclosure (for example under vacuum) housing at least part of the cryogenic components of the working circuit 2 and in particular the refrigeration heat exchanger 7 and the at least one expansion turbine 6 and the corresponding parts of the working circuit 2.

[0029] As illustrated, the cold box 9 has a generally cylindrical shape which extends in the usage configuration preferably in a horizontal longitudinal direction around the central axis 10 of revolution.

[0030] For example, the cold box 9 has a cylindrical body, preferably of circular section, the two longitudinal ends (or bottoms) of which are curved, for example of general elliptical shape.

[0031] At least one turbine 6 and, as illustrated, preferably several turbines 6 are mounted in the cold box 9 near a first longitudinal end of the cold box 9. That is to say, the turbine(s) 6 are mounted longitudinally in the cold box 9 between the refrigeration heat exchanger 7 and the longitudinal end wall 11 of the cold box 9. As illustrated, the turbine 6 or several turbines 6 are mounted transversely offset relative to the central longitudinal axis 10 of the cold box 9. That is to say, one or more turbines 6 are not mounted in the center of the end wall 11 on the central longitudinal axis 10 of revolution of the cold box 9 but transversely and / or vertically offset.

[0032] This configuration makes it possible to install several turbines 6 on the same cold box 9, even turbines 6 of relatively large size, while limiting the size of the device 1 (height and width in particular).

[0033] In the example of, and the device 1 comprises, mounted on the same longitudinal end of the cold box 9, two turbines 6. The two turbines 6 are mounted on either side of the central longitudinal axis 10, for example at mid-height of the cold box 9 or in the upper part of the cold box.

[0034] Of course, this example is in no way limiting, one or more turbines 6 could be mounted at the lower part of the end wall 11.

[0035] Similarly, one or more turbines 6 could be mounted at an end wall 11.

[0036] For example, four turbines 6 can be mounted on the same end wall 11 (bottom). For example, two turbines 6 in the lower part of the wall 11 (below and on either side of the central longitudinal axis 10) and two turbines 6 in the upper part of the wall 11 (above and on either side of the central longitudinal axis 10).

[0037] As shown schematically in , turbines 6 can be mounted at the two longitudinal ends of the cold box 9. The device 1 can thus comprise four turbines 6 distributed two on each longitudinal side of the cold box 9. This makes it possible to increase the number of machines (turbines 6) of the device and / or makes it possible to reduce the mechanical stresses imposed on each of the two end walls 11.

[0038] As illustrated, the turbines 6 may be mounted at the end of a shaft 12 of a motor 13 also driving a compressor of the compression mechanism 3. The motors 13 are located outside the cold box 9 and preferably mounted on the structure of the support 100.

[0039] These motors 13 can be connected by bolting to the rigid support. This makes it possible to take up the forces, in particular without weakening the cold box 9 through which the turbines 6 are mounted as described below.

[0040] As illustrated, the end of the shaft 12 carrying the turbine 6 can be mounted passing through in a sealed manner through the end wall 11 of the cold box 9 via a tubular tapping connection 14 mounted projecting from the outer surface of the longitudinal end wall 11 of the cold box 9.

[0041] The tubular tapping connection 14 is thus offset (not on the central longitudinal axis 10). The tubular connection 14 provides a mechanical connection (for example by welding) with the elliptical surface of the end wall 11. For this purpose, the thicknesses can be adapted locally and / or reinforcements can be provided, for example, at the connections 14.

[0042] As illustrated, the working circuit 2 comprises at least one heat exchanger 4 and preferably several non-cryogenic heat exchangers 4 located outside the cold box 9 forming part of the mechanism 4, 7 for cooling the working fluid and / or of the mechanism 7 for heating the working fluid. The heat exchangers 4 are for example of generally planar or oblong shape and mounted in and / or the support 100 preferably in respective planes perpendicular to the longitudinal direction (central axis 10). At least one part of these heat exchangers 4 can ensure a heat exchange between the working gas and a fluid 15, for example water, to ensure cooling after compression. A countercurrent exchanger 7 can also ensure a heat exchange between two flows of the working gas having different temperatures.

[0043] This improves the compactness of device 1 (optimizing the cost and footprint of the complete system).

[0044] As shown schematically in the, the heat exchangers 4 located outside the cold box 9 can be distributed on either side of the cold box 9 (in the longitudinal direction).

[0045] As illustrated, the support 100 may be composed of a structure or frame 102 comprising assembled beams and mounted on feet 101.

[0046] The support 100 may be an entity composed of several sub-structures assembled in the longitudinal direction.

[0047] The engine assemblies 13 with turbines 6 can be arranged along the longitudinal axis, on the same structure or on a separate structure.

[0048] The structure described above has good mechanical strength and is very compact. This structure can in particular be modular (depending on the number of turbines 6 and / or heat exchangers 4 to be provided.

[0049] Several pieces of equipment can be installed in the same (vertical) plane. And one or more structures supporting these elements can be provided at the level of the support 100.

Claims

A low-temperature refrigeration and / or liquefaction device, i.e. at a temperature between minus 100 degrees centigrade and minus 273 degrees centigrade, the refrigeration device (1) comprising a working circuit (2) forming a loop and containing a working fluid, the working circuit (2) comprising a working fluid compression mechanism (3) comprising at least one compressor, a working fluid cooling mechanism (4, 7), a working fluid expansion mechanism (6) comprising at least one expansion turbine (6) and a working fluid heating mechanism (7), the working circuit (2) being configured to subject the working fluid to a determined thermodynamic cycle in which the working fluid reaches a relatively low temperature at a cold end of the cycle,the device (1) comprising a refrigeration heat exchanger (7) intended to extract heat from at least one member or fluid (8) by heat exchange with the working fluid, the device comprising a thermally insulated cold box (9) housing the refrigeration heat exchanger (7) and the at least one expansion turbine (6), the cold box (9) having a generally cylindrical shape extending in a longitudinal direction around a central axis (10), said axis (10) being horizontal in the use configuration, the at least one turbine (6) being arranged in the cold box (9) near a first longitudinal end of the cold box (9), the at least one turbine (6) being mounted longitudinally in the cold box (9) between the refrigeration heat exchanger (7) and the longitudinal end wall (11) of the cold box (9),characterized in that the at least one turbine (6) is mounted offset transversely relative to the central longitudinal axis (10) of the cold box (9) and in that the at least one turbine (6) is mounted at the end of a shaft (12) of a motor (13) also driving a compressor of the compression mechanism (3), the motor (13) being located outside the cold box (9), the end of the shaft (12) carrying the turbine (6) being mounted through in a sealed manner through the end wall (11) of the cold box (9) and in that the longitudinal end wall (11) of the cold box (9) has a curved shape towards the outside of the cold box (9)., Device according to claim 1, characterized in that the end of the shaft (12) carrying the turbine (6) is mounted through in a sealed manner through the end wall (11) of the cold box (9) via a tubular tapping connection (14) mounted projecting from the outer surface of the longitudinal end wall (11) of the cold box (9). Device according to any one of claims 1 to 2, characterized in that it comprises at least one additional turbine (6) arranged in the cold box (9) near a second longitudinal end of the cold box (9), the at least one additional turbine (6) being mounted longitudinally in the cold box (9) between the refrigeration heat exchanger (7) and the end wall of the second longitudinal end of the cold box (9), in a manner offset transversely relative to the central longitudinal axis (10) of the cold box. Device according to any one of claims 1 to 3, characterized in that it is arranged in and / or on a support (100). Device according to claim 4, characterized in that the working circuit (2) comprises at least one heat exchanger (4) located outside the cold box (9) forming part of the mechanism (4) for cooling the working fluid, said at least one heat exchanger (4) being mounted in and / or on the support (100) in a plane perpendicular to the longitudinal direction (10). Device according to claim 3 or 5, characterized in that it comprises several heat exchangers (4) located outside the cold box (9) forming part of the mechanism (4) for cooling the working fluid, said heat exchangers (4) being mounted in and / or on the support (100) in respective planes perpendicular to the longitudinal direction (10). Device according to any one of claims 4 to 6, characterized in that the support (100) comprises at least one of: a set of foot(s) (102) for supporting the cold box (13), a frame (102). Device according to any one of claims 4 to 7, characterized in that the support (100) is composed of several structures assembled in the longitudinal direction.

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