CN116529540A

CN116529540A - Refrigeration system

Info

Publication number: CN116529540A
Application number: CN202180080018.5A
Authority: CN
Inventors: 植田翔太
Original assignee: Mayekawa Manufacturing Co
Current assignee: Mayekawa Manufacturing Co
Priority date: 2020-12-01
Filing date: 2021-11-25
Publication date: 2023-08-01
Also published as: US20240011673A1; JP2022087607A; WO2022118730A1

Abstract

The present invention provides a refrigeration system utilizing a brayton cycle that uses a refrigerant to generate cold energy, the refrigerant being compressed by a compressor unit disposed in a refrigerant path. The compressor unit includes: a plurality of compressors disposed in parallel with each other with respect to the refrigerant path; a plurality of first motors for driving the plurality of compressors, respectively; an expander-integrated compressor integrally formed with the expander; and a second motor for driving the expander-integrated compressor. The plurality of compressors has a larger number than the expander-integrated compressor.

Description

Refrigeration system

Technical Field

The present disclosure relates to refrigeration systems utilizing a brayton refrigeration cycle.

Background

As a refrigeration cycle, a refrigeration system using a brayton refrigeration cycle is known. The brayton refrigeration cycle is a thermodynamic cycle comprising an adiabatic compression step, an isobaric heating step, an adiabatic expansion step, and an isobaric cooling step, and is configured such that elements corresponding to the respective steps are disposed in a refrigerant line through which a refrigerant circulates. These elements constituting the refrigeration cycle are designed according to the refrigerating capacity required of the refrigerator.

Patent document 1 discloses an example of a refrigeration system using a brayton refrigeration cycle. In patent document 1, as a compressor unit corresponding to the adiabatic compression step, a compressor unit having a plurality of compressors connected in series to a refrigerant line is provided to achieve an appropriate compression ratio in accordance with a required refrigerating capacity. In addition, a part of the multistage compressor is an expander-integrated compressor having a common rotation axis with an expander corresponding to the adiabatic expansion step, and the power generated in the expander is used as a part of the power for driving the compressor, thereby improving the efficiency. In patent document 1, the amount of refrigerant circulating in the refrigeration cycle is increased by connecting compressors constituting the compressor unit in parallel, thereby improving the refrigerating capacity.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2014-219125

Disclosure of Invention

First, the technical problem to be solved

In such a refrigeration system, when a modification of a product specification having different refrigerating capacities is to be expanded, in general, each constituent element of the refrigeration system is newly designed, and cost and time required for development are required to be reduced. For example, a compressor and an expander constituting a refrigeration system need to be prepared in advance in different models according to the specifications of the refrigeration system, and if the existing models are difficult to cope with, a new model must be newly developed, which takes a lot of cost and time.

As a method for reducing the cost and time required for such new development, in the case of developing a refrigerator having a higher refrigerating capacity than an existing refrigerator, for example, as in the above-described patent document 1, although an existing configuration of a parallel refrigeration cycle can be considered, an increase in the number of required components and the occupied area cannot be avoided, which is insufficient.

At least one embodiment of the present disclosure has been made in view of the above-described circumstances, and an object thereof is to provide a refrigeration system capable of flexibly changing a design while suppressing costs, time, and occupied area at the time of installation required for development according to a required refrigeration capacity.

(II) technical scheme

To solve the above-described problems, a refrigeration system of at least one embodiment of the present disclosure provides a refrigeration system, which utilizes a brayton cycle,

the brayton cycle generates cold energy using a refrigerant, which is compressed by a compressor unit disposed on a refrigerant path,

the compressor unit includes:

a plurality of compressors disposed in parallel with each other with respect to the refrigerant path;

a plurality of first motors for driving the plurality of compressors, respectively;

an expander-integrated compressor integrally configured with an expander capable of expanding the refrigerant compressed by the compressor unit; and

a second motor for driving the expander-integrated compressor,

the plurality of compressors has a greater number than the expander-integrated compressor.

(III) beneficial effects

According to at least one embodiment of the present disclosure, a refrigeration system capable of flexibly changing a design while suppressing costs, time, and occupied area at the time of installation required for development according to a required refrigeration capacity can be provided.

Drawings

Fig. 1 is a diagram schematically showing the overall structure of a refrigeration system according to an embodiment.

Fig. 2 is a view schematically showing a sectional structure of the coaxial compressor of fig. 1.

Fig. 3 is a view schematically showing a cross-sectional structure of the expander-integrated compressor of fig. 1.

Fig. 4 is a flowchart showing a method of starting the refrigeration system of fig. 1.

Fig. 5A is a schematic diagram showing an embodiment of a refrigeration system including 2 coaxial compressors and 1 expander-integrated compressor.

Fig. 5B is a schematic diagram showing another embodiment of a refrigeration system including 2 coaxial compressors and 1 expander-integrated compressor.

Fig. 6A is a schematic diagram showing an embodiment of a refrigeration system including 3 coaxial compressors and 1 expander-integrated compressor.

Fig. 6B is a schematic diagram showing another embodiment of a refrigeration system including 3 coaxial compressors and 1 expander-integrated compressor.

Fig. 6C is a schematic diagram showing another embodiment of a refrigeration system including 3 coaxial compressors and 1 expander-integrated compressor.

Fig. 7A is a schematic diagram showing an embodiment of a refrigeration system including 3 coaxial compressors and 2 compressors integrated with an expander.

Fig. 7B is a schematic diagram showing another embodiment of a refrigeration system including 3 coaxial compressors and 2 expander-integrated compressors.

Fig. 7C is a schematic diagram showing another embodiment of a refrigeration system including 3 coaxial compressors and 2 expander-integrated compressors.

Fig. 8A is a schematic diagram showing an embodiment of a refrigeration system including 4 coaxial compressors and 2 compressors integrated with an expander.

Fig. 8B is a schematic diagram showing another embodiment of a refrigeration system including 4 coaxial compressors and 2 expander-integrated compressors.

Fig. 8C is a schematic diagram showing another embodiment of a refrigeration system including 4 coaxial compressors and 2 expander-integrated compressors.

Fig. 8D is a schematic diagram showing another embodiment of a refrigeration system including 4 coaxial compressors and 2 expander-integrated compressors.

Detailed Description

The refrigeration system according to several embodiments of the present disclosure will be described below with reference to the accompanying drawings.

However, the dimensions, materials, shapes, relative arrangements and the like of the constituent members described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention to these, but are merely illustrative examples.

The expression "relative or absolute arrangement in a certain direction", "along a certain direction", "parallel", "orthogonal", "central", "concentric" or "coaxial", for example, means not only such arrangement but also a state of relative displacement of angles and distances with a tolerance or a degree that the same function can be obtained.

For example, the expressions "identical", "equal", and "homogeneous" indicate that the objects are in an equal state, and not only strictly indicate an equal state, but also indicate a state in which there is a tolerance or a difference in the degree to which the same function can be obtained.

For example, the expression representing the shape such as a quadrangular shape and a cylindrical shape represents not only the shape such as a quadrangular shape and a cylindrical shape in a geometrically strict sense, but also the shape including the concave-convex portion, the chamfer portion, and the like within a range where the same effect can be obtained.

On the other hand, the expression "present", "having", "including", or "having" one component is not an exclusive expression that excludes the presence of other components.

First, the overall structure of a refrigeration system 100 according to an embodiment will be described with reference to fig. 1. Fig. 1 is a diagram schematically showing the overall structure of a refrigeration system 100 according to an embodiment.

The refrigeration system 100 includes, in order on a refrigerant path 101 through which a refrigerant flows: a compressor unit 102 (110A, 110B, 110C) for compressing a refrigerant; an expander 103 that expands the refrigerant; a cooling unit 104 configured by a heat exchanger for performing heat exchange between the refrigerant and the cooling target; and a cold energy recovery heat exchanger 105 for recovering cold energy remaining in the refrigerant after passing through the cooling unit 104, thereby forming a brayton cycle of a counter-flow heat exchanger type based on a refrigerating cycle of steady circulation flow.

The refrigeration system 100 has a superconducting device 106 as a cooling object, and the superconducting device 106 uses a superconductor capable of exhibiting superconductivity in a very low temperature state. Superconducting device 106 is, for example, a superconducting cable. In order to maintain the extremely low temperature state of the superconducting device 106, the refrigeration system 100 has a refrigerant path 107 through which liquid nitrogen cooled by the cooling portion 104 circulates. The refrigerant path 107 is configured to be capable of exchanging heat with the refrigerant flowing through the refrigerant path 101 of the refrigeration system 100 via the cooling unit 104, and is provided with a pump 108 for circulating liquid nitrogen. Thereby, the liquid nitrogen flowing through the refrigerant path 107 that has been warmed up due to the heat load of the superconducting device 106 is cooled by heat exchange with the refrigerant flowing through the refrigerant path 101 cooled by the refrigeration system 100.

In the refrigerant path 101 of the refrigeration system 100, neon or the like is used as the refrigerant, but the present invention is not limited thereto, and the type of gas may be appropriately changed according to the cooling temperature or the like.

In the refrigeration system 100, an expander 103 through which a relatively low-temperature refrigerant flows, a cooling unit 104, and a cold energy recovery heat exchanger 105 are housed in a cold box 109 that can be insulated from the outside.

The cooling box 109 has a vacuum heat insulating layer between the inner and outer surfaces, for example, to prevent heat from entering from the outside and reduce heat loss in the expander 103, the cooling unit 104, and the cold energy recovery heat exchanger 105 housed in the cooling box 109. On the other hand, the compressor unit 102 in the refrigeration system 100 is configured to be disposed outside the above-described cold box 109, since a relatively high-temperature refrigerant flows therethrough.

The cold box 109 is disposed at a position closer to the superconducting device 106 as a cooling target than the compressor unit 102. This allows the cooling energy generated in the cooling box 109 to be supplied to the cooling target with less loss, and thus good freezing efficiency can be achieved. The compressor unit 102 is configured separately from the cold box 109, and the degree of freedom in layout increases, and for example, the space for installing the refrigeration system can be reduced by being disposed in the cold box.

The compressor unit 102 includes a plurality of compressors 110 connected to the refrigerant path 101 in series with each other. In the present embodiment, the compressor unit 102 is configured by including: a low-stage compressor 110A capable of compressing a fluid; a middle stage compressor 110B capable of further compressing the fluid compressed by the low stage compressor 110A; and a high-stage compressor 110C capable of further compressing the fluid compressed by the intermediate-stage compressor 110B, wherein the low-stage compressor 110A, the intermediate-stage compressor 110B, and the high-stage compressor 110C are connected in series to the refrigerant path 101, and configured to be capable of multi-stage compression of 3 stages in total.

Further, the number of compression stages in the compressor unit 102 may be any number.

In the compressor unit 102, a heat exchanger 112 is provided downstream of each of the plurality of compressors 110, and the heat exchanger 112 is configured to cool the refrigerant warmed by adiabatic compression by heat exchange with cooling water. Specifically, the heat exchanger 112A is disposed downstream of the low-stage compressor 110A, the heat exchanger 112B is disposed downstream of the intermediate-stage compressor 110B, and the heat exchanger 112C is disposed downstream of the high-stage compressor 110C.

The refrigerant flowing through the refrigerant path 101 is first heat-insulated and compressed by the low-stage compressor 110A located on the most upstream side to have a temperature increased, and then cooled by heat exchange with cooling water at the heat exchanger 112A provided on the downstream side. Thereafter, the refrigerant is compressed again by the intermediate-stage compressor 110B while being insulated from heat, and then cooled by heat exchange with cooling water at the heat exchanger 112B provided on the downstream side. Further, the refrigerant is heat-insulated and compressed again by the high-stage compressor 110C, and then, after the temperature thereof has risen, is cooled by heat exchange with cooling water at the heat exchanger 112C provided on the downstream side.

Accordingly, in the compressor unit 102, heat-insulating compression by the compressor 110 and cooling by the heat exchanger 112 are repeatedly performed in multiple stages, thereby improving efficiency. That is, by repeating the heat-insulating compression and the cooling in a plurality of stages, the compression process in the brayton cycle can be made close to ideal isothermal compression. Although the isothermal compression is approximated as the number of stages increases, the number of stages is preferably determined in consideration of the selection of the compression ratio, the complexity of the device structure, the ease of operation, and the like, which are caused by the increase of the number of stages.

The refrigerant compressed by the compressor unit 102 is cooled by the cold energy recovery heat exchanger 105, and then expanded by the expander 103 with heat insulation, thereby generating cold energy. The refrigerant discharged from the expander 103 exchanges heat with liquid nitrogen flowing through the refrigerant path 107 on the cooling target side in the cooling unit 104, and the temperature rises due to the heat load.

The refrigerant having been warmed in the cooling unit 104 is introduced into the cold energy recovery heat exchanger 105, and undergoes heat exchange with the high-temperature compressed refrigerant having passed through the heat exchanger 112C in the compressor unit 102, whereby remaining cold energy is recovered. This reduces the temperature of the refrigerant introduced into the expander 103, and can obtain cold energy at a lower temperature.

In such a refrigeration system 100, a brayton cycle is configured using a plurality of rotary machines such as a plurality of compressors 110 and an expander 103 included in the compressor unit 102. Here, the low-stage compressor 110A and the high-stage compressor 110C are configured as coaxial compressors 118 connected to both ends of the output shaft 116A (see fig. 2) of the first motor 114A, which is a common power source, respectively, so that the number of components can be reduced and the installation space can be made smaller. The intermediate-stage compressor 110B and the expander 103 are also configured as the expander-integrated compressor 120 connected to both ends of the output shaft 116B (see fig. 3) of the second motor 114B, which is a common power source, so that the number of components can be reduced, the layout can be made into a small installation space, and the compression power of the intermediate-stage compressor 110B is assisted by the power generated in the expander 103, thereby achieving an improvement in efficiency.

Among the plurality of compressors 110 included in the compressor unit 102, any of the compressors may be configured as the coaxial compressor 118, and any of the compressors may be configured as the expander-integrated compressor 120.

The configuration of the coaxial compressor 118 and the expander-integrated compressor 120 will be described with reference to fig. 2 and 3. Fig. 2 is a view schematically showing a cross-sectional structure of the coaxial compressor 118 of fig. 1, and fig. 3 is a view schematically showing a cross-sectional structure of the expander-integrated compressor 120 of fig. 1.

As shown in fig. 2, the coaxial compressor 118 is configured by connecting the low-stage compressor 110A and the high-stage compressor 110C to both sides of the output shaft 116A of the first motor 114A. In the present embodiment, the first motor 114A is disposed between the low-stage compressor 110A and the high-stage compressor 110C, but in another embodiment, may be disposed outside the low-stage compressor 110A and the high-stage compressor 110C (for example, the first motor 114A, the low-stage compressor 110A, and the high-stage compressor 110C may be disposed in the axial direction of the output shaft 116A).

The output shaft 116A of the first motor 114A is supported so as to be rotatable in a noncontact manner with respect to the motor housing 130-1 by a radial magnetic bearing 122-1 and a thrust magnetic bearing 126-1 disposed between the low-stage compressor 110A and the high-stage compressor 110C. Radial magnetic bearings 122-1 are provided on both sides of the first motor 114A in the axial direction of the output shaft 116A, and magnetically levitate the output shaft 116A to bear a radial load. The thrust magnetic bearing 126-1 is provided on one side of the first motor 114A in the axial direction of the output shaft 116A (between the first motor 114A and the low-stage compressor 110A in the embodiment shown in fig. 2), and magnetically bears the thrust load of the output shaft 116A so as to form a gap with an axial turntable 127-1 provided on the output shaft 116A.

In addition, a thrust magnetic bearing 126-1 and an axial turntable 127-1 may also be disposed between the advanced compressor 110C and the first motor 114A. In the present embodiment, the axial turntable 127-1 is provided on one side of the first motor 114A mainly for suppressing fluid friction loss, but may be provided on both sides for assembly reasons or the like when the outer diameter of the output shaft 116A of the first motor 114A is large.

The housing 128-1 of the coaxial compressor 118 is configured by connecting a motor housing 130-1, a low-stage compressor impeller housing 132-1, and a high-stage compressor impeller housing 132-3 to each other along the axial direction of the output shaft 116A. The motor housing 130-1 is a housing defining a housing of the first motor 114A, and houses therein: a rotor 136A integrally formed with the output shaft 116A, and a stator 138A disposed in the vicinity of the rotor 136A (the rotor 136A integrally formed with the output shaft 116A). The impeller housing 132-1 for the low-stage compressor accommodates an impeller 140A of the low-stage compressor 110A attached to one end side of the output shaft 116A. The impeller housing 132-3 for the high-stage compressor accommodates the impeller 140C of the high-stage compressor 110C attached to the other end side of the output shaft 116A.

As shown in fig. 3, the expander-integrated compressor 120 is configured by connecting the intermediate-stage compressor 110B and the expander 103 to both sides of the output shaft 116B of the second motor 114B. Although the second motor 114B is disposed between the intermediate-stage compressor 110B and the expander 103 in the present embodiment, it may be disposed outside the intermediate-stage compressor 110B and the expander 103 in another embodiment (for example, the second motor 114B, the intermediate-stage compressor 110B, and the expander 103 may be disposed in this order in the axial direction of the output shaft 116B).

The output shaft 116B of the second motor 114B is supported so as to be rotatable in a noncontact manner with respect to the motor housing 130-2 via a radial magnetic bearing 122-2 and a thrust magnetic bearing 126-2 disposed between the intermediate-stage compressor 110B and the expander 103. Radial magnetic bearings 122-2 are provided on both sides of the second motor 114B in the axial direction of the output shaft 116B, and magnetically levitate the output shaft 116B to bear a radial load. The thrust magnetic bearing 126-2 is provided on one side of the second motor 114B (between the second motor 114B and the intermediate-stage compressor 110B in the embodiment shown in fig. 3) in the axial direction of the output shaft 116B, and magnetically bears the thrust load of the output shaft 116B so as to form a gap with an axial turntable 127-2 provided on the output shaft 116B.

In addition, a thrust magnetic bearing 126-2 and an axial turntable 127-2 may also be provided between the expander 103 and the second motor 114B. In the present embodiment, the axial turntable 127-2 is provided on one side of the second motor 114B mainly for suppressing fluid friction loss, but may be provided on both sides for assembly reasons or the like when the outer diameter of the output shaft 116B of the second motor 114B is large.

The casing 128-2 of the expander-integrated compressor 120 is configured by connecting a motor casing 130-2, a middle-stage compressor impeller casing 132-2, and an expander impeller casing 134-1 to each other along the axial direction of the output shaft 116B. The motor housing 130-2 is a housing defining a casing of the second motor 114B, and houses therein: a rotor 136B integrally formed with the output shaft 116B (the rotor 136B integrally formed with the output shaft 116B), and a stator 138B disposed in the vicinity of the rotor 136B. The impeller housing 132-2 for the intermediate-stage compressor accommodates an impeller 140B of the intermediate-stage compressor 110B attached to one end side of the output shaft 116B. The expander impeller housing 134-1 accommodates an impeller 142 of the expander 103 attached to the other end side of the output shaft 116B.

Returning to fig. 1, the compressor unit 102 includes a plurality of coaxial compressors 118 arranged in parallel with each other in the refrigerant path 101. The number of the compressors 118 included in the compressor unit 102 is greater than the number of the compressors 120 integrated with the expander included in the compressor unit 102, and is set according to the refrigerating capacity required for the refrigerating system 100. In the present embodiment, the compressor unit 102 includes 2 coaxial compressors 118A and 118B for 1 expander-integrated compressor 120, but it is also possible to provide a larger refrigerating capacity by providing 3 or more coaxial compressors 118. In addition, when there are 2 compressors 120 integrated with the expander, 3 or more coaxial compressors 118 may be provided.

The number of the coaxial compressors 118 included in the compressor unit 102 is set according to the refrigerating capacity required for the refrigerating system 100. For example, when the refrigerating capacity required for the refrigeration system 100 increases, the number of the coaxial compressors 118 can be increased to cope with the increase in the flow rate of the refrigerant flowing through the refrigerant path 101. Therefore, the refrigeration system 100 can realize specifications having different refrigeration capacities with a small development load by adjusting the number of the coaxial compressors 118 included in the compressor unit 102. Since the expander-integrated compressor 120 can cope with only changing the design of the components (the impeller housings 132-2 and 134-1) associated with the impeller 140B and the expander impeller 142 of the intermediate-stage compressor 110B, the development time and cost of the coaxial compressor corresponding to the types of components and the refrigerating capacity required for the refrigeration system 100 can be effectively suppressed. In addition, the occupied area can be reduced as compared with the case where the refrigerating capacity required for disposing a plurality of refrigerating systems 100 in parallel is handled.

In the refrigeration system 100, the first motor 114A of the coaxial compressor 118 and the second motor 114B of the expander-integrated compressor 120 are common. By setting the motor for driving to the common standard between the coaxial compressor 118 and the expander-integrated compressor 120 in this way, it is possible to realize the refrigeration system 100 having different refrigeration capacities while reducing development load.

The plurality of first motors and the plurality of second motors are "shared" means that at least a part of the specifications of both motors are shared. At least a part of the specifications may be the same in terms of at least a part of the output, rotation speed, size, etc. of the motor, or may be replaced with each other, or may be designed to be the same to such an extent that the assembly of the components other than the motor is not affected.

When the refrigeration capacity required for the refrigeration system 100 is 5kW, for example, the required output of the first motor used for the coaxial compressor 118 is 45kW and the required output of the second motor used for the expander-integrated compressor 120 is 15kW. Based on such a precondition, in the case of developing the refrigeration system 100 of 10kW doubling the refrigerating capacity, since the amount of refrigerant flowing through the refrigerant path 101 increases doubly, the required output to the first motor becomes 90kW (=45 kw×2) and the required output to the second motor becomes 30kW (=15 kw×2). In the refrigeration system 100 according to the present embodiment, as shown in fig. 1, such a requirement can be satisfied by providing 2 coaxial compressors 118 having the first motor with an output of 45kW, which is the same as the basic design specification, in parallel to the refrigerant path 101, without requiring a new design of the coaxial compressors. At this time, in the expander-integrated compressor 120, the second motor 114B can provide 30kW as the required output by adopting the output specification of 45kW as in the first motor 114A.

In this way, by adopting a common (same-specification) motor as the first motor 114A and the second motor 114B, the peripheral structures of the first motor 114A and the second motor 114B can be made common. For example, since the first motor 114A and the second motor 114B are common (same specification), the output shaft 116A and the output shaft 116B have the same shaft diameter, and as a result, the bearings (radial magnetic bearing 122-1 and thrust magnetic bearing 126-1) for supporting the output shaft 116A in the coaxial compressor 118 and the bearings (radial magnetic bearing 122-2 and thrust magnetic bearing 126-2) for supporting the output shaft 116B in the expander-integrated compressor 120 can be made common (same specification). The motor housing 130-1 of the first motor 114A and the motor housing 130-2 of the second motor 114B can be made common (same standard).

The term "common" used for the bearings and the motor housing means that at least a part of the specifications of both are common. At least a part of the specifications may be replaced with each other, or may be designed to be identical to each other to such an extent that the assembly of the components other than the motor is not affected.

The low-stage compressor impeller housing 132-1 and the high-stage compressor impeller housing 132-3 of the first motor 114A and the intermediate-stage compressor impeller housing 132-2 and the expander impeller housing 134-1 of the second motor 114B may be designed differently according to the shapes of the impellers to be housed.

In this way, in the refrigeration system 100, by sharing the first motor 114A and the second motor 114B included in the compressor unit 102 and their peripheral structures (the same specifications), even when the refrigeration capacity required for the refrigeration system 100 is changed, the design can be efficiently performed with a small development burden.

Fig. 1 illustrates a case where 2 coaxial compressors 118 are included in the compressor unit 102. The 2 coaxial compressors 118 are disposed in parallel with each other with respect to the refrigerant path 101. The refrigerant path 101 includes: a first line 144 for supplying refrigerant from the cold energy recovery heat exchanger 105 to the compressor unit 102; second lines 146A, 146B branched from the downstream side of the first line 144 with respect to the low-stage compressors 110A of the 2 coaxial compressors 118, respectively; third lines 148A, 148B through which the refrigerant compressed by the 2 low-stage compressors 110A flows, respectively; a fourth line 150 connecting the third lines 148A and 148B to the intermediate-stage compressor 110B, and joining the third lines on the downstream side; a fifth line 152 through which the refrigerant compressed by the intermediate stage compressor 110B flows; sixth lines 154A, 154B branching from the downstream side of the fifth line 152 to the high-stage compressor 110C of the 2 in-line compressors 118, respectively; seventh lines 156A, 156B through which the refrigerant compressed by the high-stage compressor 110C flows, respectively; and an eighth line 158 in which the seventh lines 156A and 156B merge on the downstream side and are connected to the cold energy recovery heat exchanger 105 on the cold box 109 side.

By providing the first valve 160 in one of the second lines 146A and 146B (the second line 146B in fig. 1), the distribution ratio of the refrigerant to the low-stage compressor 110A of the 2-stage coaxial compressors 118 can be adjusted. Further, by providing the second valve 162 in one of the third lines 148A and 148B (the third line 148B in fig. 1) through which the refrigerant compressed by the 2 low-stage compressors 110A flows, the discharge rate of the refrigerant from the 2 low-stage compressors 110A can be adjusted.

The aforementioned heat exchanger 112A is provided in each of the third lines 148A and 148B.

By providing the third valve 164 in one of the seventh lines 156A and 156B (the seventh line 156B in fig. 1), the discharge rate of the refrigerant from the high-stage compressor 110C of the 2-stage coaxial compressors 118 can be adjusted.

The seventh lines 156A and 156B are provided with the heat exchangers 112C described above, respectively.

In the refrigeration system 100, a first bypass line 166 is provided that communicates the upstream side and the downstream side of the low-stage compressor 110A of the 2 coaxial compressors 118. A first bypass valve 168 is provided in the first bypass line 166. A second bypass line 170 is provided to communicate the upstream side and the downstream side of the intermediate-stage compressor 110B. A second bypass valve 172 is provided in the second bypass line 170. In addition, a third bypass line 174 is provided that communicates the upstream side and the downstream side of the high-stage compressor 110C of the 2 coaxial compressors 118. A third bypass valve 176 is provided in the third bypass line 174.

In addition, a fourth bypass line 182 that communicates between the high-pressure refrigerant line 178 and the low-pressure refrigerant line 180 in the refrigerant path 101 is provided, the high-pressure refrigerant line 178 being between the downstream side of the high-stage compressor 110C and the cold energy recovery heat exchanger 105, and the low-pressure refrigerant line 180 being between the cold energy recovery heat exchanger 105 and the low-stage compressor 110A. A buffer tank 184 capable of storing the refrigerant, and a fourth valve 186 and a fifth valve 188 provided on the upstream side and the downstream side of the buffer tank 184, respectively, are disposed on the fourth bypass line 182.

These valves are configured to control the opening degree based on a control signal from the control device 200 as a control unit of the refrigeration system 100, so that the flow path of the refrigerant in the refrigerant path 101 can be appropriately switched. The control device 200 is configured by, for example, installing a program for executing predetermined control on a hardware configuration including an electronic computing device such as a computer.

The arrangement of the valves and the bypass valve in the refrigeration system 100 can be changed as appropriate within a range in which the same control can be achieved.

Next, a method of starting the refrigeration system 100 having the above-described structure will be described. Fig. 4 is a flowchart illustrating a method of starting the refrigeration system 100 of fig. 1.

First, as an initial state of the refrigeration system 100, a case is assumed in which the temperature of the refrigerant at the inlet of the expander 103 is normal temperature (about 300K). In the refrigeration system 100 in the stopped state, the temperature of the refrigerant remaining in the refrigerant path 101 increases to a temperature near the normal temperature (about 300K), and the pressure of the refrigerant in the refrigerant path 101 increases. In this state, the pressure of the refrigerant in the refrigerant path 101 from the high-pressure refrigerant line 178 from the high-stage compressor 110C to the expander 103 is equalized (high-low pressure balance) with the pressure of the refrigerant in the low-pressure refrigerant line 180 from the expander 103 to the low-stage compressor 110A. In such a state, the pressure on the low-pressure refrigerant line 180 side is higher than that in the normal operation, and when the refrigeration system 100 is started and operated in a state in which the refrigerant pressure is high, the pressure on the high-pressure refrigerant line 178 side tends to rise excessively, and in particular, the motor load may be high because the expander-integrated compressor 120 is configured to be provided with a motor drive.

Therefore, when the pressure difference Δp between the pressure of the high-pressure refrigerant line 178 and the pressure inside the buffer tank 184 exceeds a predetermined threshold Δp1 (for example, 10 kPa) (yes in step S1), the control device 200 controls the fourth valve 186 to open (step S2) and recovers a part of the refrigerant flowing through the refrigerant path 101 into the buffer tank 184 (step S3). As a result, the pressure difference Δp is reduced, and the pressure of the high-pressure refrigerant line 178 is prevented from rising excessively, so that the occurrence of excessive motor load can be appropriately avoided. Thereafter, when the pressure difference Δp becomes equal to or smaller than the threshold value Δp1 (yes in step S4), the control device 200 controls the fourth valve 186 to be closed (step S5).

When the pressure difference Δp is larger than the threshold Δp1 (step S4: no), the control device 200 returns the control to step S2.

The pressure difference Δp can be obtained by, for example, a difference between a pressure sensor provided in the high-pressure refrigerant line 178 and a detection value of a pressure sensor provided in the buffer tank 184.

In the refrigerant path 101, the flow path near the inlet of the expander 103 having the highest density under the rated operation condition has the smallest cross section. Since the suction temperature of the expander 103 is higher than the rated condition (the refrigerant density is low) at the time of pre-cooling, the compressor may surge due to the choke phenomenon of the expander 103 in which the refrigerant flow amount at this portion becomes small. In the next step S6, in order to solve such a problem, only one of the 2 coaxial compressors 118 included in the compressor unit 102 (the coaxial compressor 118A) is started together with the expander-integrated compressor 120 (that is, only one of the 2 coaxial compressors 118 is operated together with the expander-integrated compressor 120, so-called console number operation is started). This enables the start-up in a state where the flow rate of the refrigerant in the expander 103 is reduced, and thus the occurrence of surge in the compressor can be effectively prevented.

Next, the control device 200 is based on the temperature T of the refrigerant at the inlet of the expander 103 _in And the opening degree of the second bypass valve 172 is controlled (step S7). In step S7, based on the temperature T of the refrigerant at the inlet of the expander 103 _in Controlling the opening of the second bypass valve 172, thereby flowingA portion of the refrigerant passing through the refrigerant path 101 bypasses the intermediate stage compressor 110B via the second bypass line 170. As a result, the flow rate of the refrigerant supplied to the intermediate-stage compressor 110B increases, and surging in the compressor can be prevented more effectively.

The opening degree control of the second bypass valve 172 in the further step S7 may be based on the temperature T of the refrigerant at the inlet of the expander 103 _in And is carried out continuously, or in stages (stepwise). At this time, the rotation speed of at least one of the coaxial compressor 118 and the expander-integrated compressor 120 that are started in step S6 may be controlled in a coordinated manner so that the cooling rate of the refrigerant in the cold energy recovery heat exchanger 105 is substantially constant (for example, 60K/h).

Further, the temperature T of the refrigerant at the inlet of the expander 103 _in Can be obtained by a temperature sensor (not shown) provided at the inlet of the expander 103.

In step S7, the first, second, and third valves 160, 162, and 164, and the first and third bypass valves 168, 176 are controlled to be closed.

Next, when the temperature T at the inlet of the expander 103 _in When the pressure becomes equal to or lower than the first target value T1 (for example, 180 to 200K) (yes in step S8), the control device 200 controls the first bypass valve 168, the third bypass valve 176, and the first valve 160 to open (step S9).

Next, the control device 200 determines whether or not there is surge (step S10), and if it determines that there is surge (yes in step S10), it performs control so as to reduce the rotation speed of the one coaxial compressor 118A started in step S6 (step S11). The rotational speed of the one of the coaxial compressors 118A controlled in step S11 is controlled as follows: the rotation speed is reduced so that surging does not occur in each of the 2 coaxial compressors 118 included in the compressor unit 102, assuming that both compressors are started.

In step S11, the rotational speed of one of the coaxial compressors 118A may be temporarily reduced to a stopped state. If it is determined that there is no surge (no in step S10), the control for reducing the rotation speed in step S11 is not performed. For example, when the rotation speed is relatively low (for example, when the rotation speed at the time of precooling is low due to a restriction such as a cooling speed of a heat exchanger), since surging tends not to occur easily, the control for reducing the rotation speed as in step S11 can be omitted depending on the operation conditions.

Next, the control device 200 controls the first bypass valve 168 and the third bypass valve 176 to open (step S12), and starts the other coaxial compressor 118B included in the compressor unit 102 (step S13). At this time, the rotation speed of the other coaxial compressor 118B is controlled to be equal to the rotation speed of the one coaxial compressor 118A reduced in step S6. When the pressure conditions of the 2 coaxial compressors 118 become equal (yes in step S14), the control device controls the first bypass valve 168 and the third bypass valve 176 to be closed (step S15).

Next, the control device 200 controls the second valve 162 and the third valve 164 to open, thereby completing the connection of the other coaxial compressor 118B to the refrigerant path 101 (step S16). In this way, in a state where the rotation speed of one of the coaxial compressors 118A started first in step S3 is temporarily reduced, by starting the other coaxial compressor 118B, it is possible to prevent surging from occurring in each compressor and smoothly transition from the one-side operation based on 1 coaxial compressor 118A to the two-side operation based on 2 coaxial compressors 118A, 118B.

The control device 200 is then based on the temperature T of the refrigerant at the inlet of the expander 103 _in The cooling rate of the refrigerant in the heat exchanger 105 controls the opening degree of the second bypass valve 172, and the rotation speed of at least one of the compressor 118 and the compressor 120 is controlled, thereby advancing the precooling operation. Also, when the temperature T at the inlet of the expander 103 _in When the temperature becomes equal to or lower than the second target temperature T2 (for example, 100 to 120K) (yes in step S17), the control device 200 controls the second bypass valve 172 to close (step S18), and the cooling system is switched to the normal operation after the precooling is completed, whereby the start-up control of the series of refrigeration systems 100 is completed (step S19).

In the case where the refrigeration system 100 includes 3 or more coaxial compressors 118Then, according to the above control, the number of the coaxial compressors 118 in the activated state is sequentially increased, whereby the temperature T can be set _in To a desired value.

As described above, in the method of starting the refrigeration system 100, at the initial stage of starting, the in-line compressor 118 included in the compressor unit 102 is started up to be controlled so that the pre-cooling (with the temperature T at the inlet of the expander 103) proceeds _in Decrease) and increase the number of starts of the coaxial compressors 118. The number of start-up stages of the in-line compressors 118 in each stage may be based on, for example, the temperature T at the inlet of the expander 103 _in The control is performed as follows.

The mass flow rate G of the refrigerant passing through the expander 103 is expressed as the temperature T of the refrigerant at the inlet of the expander 103 based on the relationship between the sonic velocity, mach number, and adiabatic flow, as described below _in Is not critical, i.e., the nozzle outlet flow rate of the expander 103 does not reach sonic velocity and the refrigerant is an ideal gas

[ number 1]

Where A is the nozzle throat area, P, of the expander 103 _in 、P _ex The pressure at the inlet and outlet of the expander 103, respectively, κ is the specific heat ratio of the refrigerant, and R is the gas constant of the ideal gas. By the expression (1), the temperature T at the inlet to the expander 103 can be estimated _in Is provided. Therefore, if the discharge flow rate of each of the coaxial compressors 118 is R, the number D of the coaxial compressors 118 to be started can be obtained by the following equation (mantissa is rounded up).

D＝G/R (2)

As shown in fig. 1, when 2 in-line compressors 118 are included in the compressor unit 102, the temperature T at the inlet of the expander 103 _in Before the first target value T1 (for example, 180 to 200K) is reached, only one of the coaxial compressors 118 is started to be able to be startedAlthough pre-cooling is performed efficiently, the efficiency is reduced for the second target value T2 (for example, 120 to 200K), and thus it is preferable to start the other coaxial compressor 118 to perform 2 operations. When the number of operating stages of the coaxial compressor 118 is changed in accordance with the temperature range in this manner, the number of operating stages can be smoothly changed while preventing the occurrence of surging by temporarily reducing the rotational speed of the started coaxial compressor 1 as described above under the operating conditions in which surging is likely to occur.

In the above embodiment, the refrigeration system 100 having 2 coaxial compressors 118 for 1 expander-integrated compressor has been described, but the number of expander-integrated compressors 120 and the number of coaxial compressors 118 in the refrigeration system 100 may be any number. Some modifications of the refrigeration system 100 will be described in detail below with reference to fig. 5 to 8.

Fig. 5 to 8 show the coaxial compressor 118, the expander-integrated compressor 120, the first motor 114A, and the second motor 114B of the refrigeration system 100 in a simplified manner, and other configurations are similar to those of the above-described embodiments, and detailed descriptions thereof are omitted.

Fig. 5A to 5B are schematic diagrams showing refrigeration systems 100A-1 to 100A-2 each including 2 coaxial compressors 118A and 118B and 1 expander-integrated compressor 120. In the refrigeration system 100A-1 shown in fig. 5A, the first motor 114A-1 for driving the coaxial compressor 118A, the first motor 114A-2 for driving the coaxial compressor 118B, and the second motor 114B for driving the expander-integrated compressor 120 are all common as in the foregoing embodiments. In this case, by sharing the first motor 114A and the second motor 114B, the types of motors used in the refrigeration system 100A can be minimized, and the cost and time required for development can be effectively reduced.

In the refrigeration system 100A-2 shown in fig. 5B, the first motor 114A-1 for driving the coaxial compressor 118A and the second motor 114B for driving the expander-integrated compressor 120 are common, while the first motor 114A-2 for driving the coaxial compressor 118B is different (is of another specification). In this way, the first motor 114A and the second motor 114B used in the refrigeration system 100 can be made common as much as possible, and at the same time, only a part of the motors can be made to have other specifications, so that it is possible to flexibly cope with the specifications required for the refrigeration system 100.

Next, fig. 6A to 6C are schematic diagrams showing refrigeration systems 100B-1 to 100B-3 each including 3 coaxial compressors 118A, 118B, 118C and 1 expander-integrated compressor 120. In the refrigeration system 100B-1 shown in FIG. 6A, the first motor 114A-1 for driving the coaxial compressor 118A, the first motor 114A-2 for driving the coaxial compressor 118B, the first motor 114A-3 for driving the coaxial compressor 118C, and the second motor 114B for driving the expander-integrated compressor 120 are all in common. In this case, by sharing all of the first motors 114A and the second motors 114B, the types of motors used in the refrigeration system 100A can be minimized, and the cost and time required for development can be effectively reduced.

In the refrigeration system 100B-2 shown in fig. 6B, the first motor 114A-1 for driving the coaxial compressor 118A, the first motor 114A-2 for driving the coaxial compressor 118B, and the second motor 114B for driving the expander-integrated compressor 120 are common, but the first motor 114A-3 for driving the coaxial compressor 118C is different (is of another specification). In this way, the common use of the first motor 114A and the second motor 114B for the refrigeration system 100 can be performed as much as possible, and at the same time, only a part of the motors can be made to have other specifications, thereby flexibly coping with the specifications required for the refrigeration system 100.

In the refrigeration system 100B-3 shown in fig. 6C, the first motor 114A-1 for driving the coaxial compressor 118A and the second motor 114B for driving the expander-integrated compressor 120 are common to each other, while the first motor 114A-2 for driving the coaxial compressor 118B and the first motor 114A-3 for driving the coaxial compressor 118C are common to each other. As described above, the motors used in the refrigeration system 100 can flexibly meet the specifications required for the refrigeration system 100 by sharing the motors with respect to a plurality of different specifications.

Next, fig. 7A to 7C are schematic diagrams showing refrigeration systems 100C-1 to 100C-3 each including 3 coaxial compressors 118A, 118B, 118C and 2 expander-integrated compressors 120A, 120B. In the refrigeration system 100C-1 shown in FIG. 7A, the first motor 114A-1 for driving the coaxial compressor 118A, the first motor 114A-2 for driving the coaxial compressor 118B, the first motor 114A-3 for driving the coaxial compressor 118C, the second motor 114B-1 for driving the expander-integrated compressor 120A, and the second motor 114B-2 for driving the expander-integrated compressor 120B are all in common. In this case, by sharing all of the first motor 114A and the second motor 114B, the types of motors used in the refrigeration system 100A can be minimized, and the cost and time required for development can be effectively reduced.

In the refrigeration system 100C-2 shown in FIG. 7B, the first motor 114A-1 for driving the coaxial compressor 118A, the first motor 114A-2 for driving the coaxial compressor 118B, the second motor 114B-1 for driving the expander-integrated compressor 120A, and the second motor 114B-2 for driving the expander-integrated compressor 120B are common, but the first motor 114A-3 for driving the coaxial compressor 118C is different (is of another specification). In this way, the common use of the first motor 114A and the second motor 114B for the refrigeration system 100 can be performed as much as possible, and at the same time, only a part of the motors can be made to have other specifications, thereby flexibly coping with the specifications required for the refrigeration system 100.

In the refrigeration system 100C-3 shown in FIG. 7C, the first motor 114A-1 for driving the coaxial compressor 118A, the second motor 114B-1 for driving the expander-integrated compressor 120A, and the second motor 114B-2 for driving the expander-integrated compressor 120B are in common with each other, while the first motor 114A-2 for driving the coaxial compressor 118B and the first motor 114A-3 for driving the coaxial compressor 118C are in common with each other. As described above, the motors used in the refrigeration system 100 can flexibly meet the specifications required for the refrigeration system 100 by sharing the motors with respect to a plurality of different specifications.

Fig. 8A to 8D are schematic diagrams showing refrigeration systems 100D-1 to 100D-4 each including 4 coaxial compressors 118A, 118B, 118C, 118D and 2 expander-integrated compressors 120A, 120B. In the refrigeration system 100D-1 shown in FIG. 8A, the first motor 114A-1 for driving the coaxial compressor 118A, the first motor 114A-2 for driving the coaxial compressor 118B, the first motor 114A-3 for driving the coaxial compressor 118C, the first motor 114A-4 for driving the coaxial compressor 118D, the second motor 114B-1 for driving the expander-integrated compressor 120A, and the second motor 114B-2 for driving the expander-integrated compressor 120B are all in common. In this case, by sharing all of the first motor 114A and the second motor 114B, the types of motors used in the refrigeration system 100A can be minimized, and the cost and time required for development can be effectively reduced.

In the refrigeration system 100D-2 shown in FIG. 8B, the first motor 114A-1 for driving the coaxial compressor 118A, the first motor 114A-2 for driving the coaxial compressor 118B, the first motor 114A-3 for driving the coaxial compressor 118C, the second motor 114B-1 for driving the expander-integrated compressor 120A, and the second motor 114B-2 for driving the expander-integrated compressor 120B are common, while the first motor 114A-4 for driving the coaxial compressor 118D is different (is of other specifications). In this way, the common use of the first motor 114A and the second motor 114B for the refrigeration system 100 can be performed as much as possible, and at the same time, only a part of the motors can be made to have other specifications, thereby flexibly coping with the specifications required for the refrigeration system 100.

In the refrigeration system 100D-3 shown in FIG. 8C, the first motor 114A-1 for driving the coaxial compressor 118A, the first motor 114A-2 for driving the coaxial compressor 118B, the second motor 114B-1 for driving the expander-integrated compressor 120A, and the second motor 114B-2 for driving the expander-integrated compressor 120B are in common with each other, while the first motor 114A-3 for driving the coaxial compressor 118C and the first motor 114A-4 for driving the coaxial compressor 118D are in common with each other. As described above, the motors used in the refrigeration system 100 can flexibly meet the specifications required for the refrigeration system 100 by sharing the motors with respect to a plurality of different specifications.

In the refrigeration system 100D-4 shown in FIG. 8D, the first motor 114A-1 for driving the coaxial compressor 118A, the second motor 114B-1 for driving the expander-integrated compressor 120A, and the second motor 114B-2 for driving the expander-integrated compressor 120B are in common with each other, while the first motor 114A-2 for driving the coaxial compressor 118B, the first motor 114A-3 for driving the coaxial compressor 118C, and the first motor 114A-4 for driving the coaxial compressor 118D are in common with each other. As described above, the motors used in the refrigeration system 100 can flexibly meet the specifications required for the refrigeration system 100 by sharing the motors with respect to a plurality of different specifications.

The content described in the above embodiment is grasped as follows, for example.

(1) One mode of the refrigeration system is

A refrigeration system, such as refrigeration system 100 of the above-described embodiment, utilizes a brayton cycle that generates refrigeration energy using a refrigerant compressed by a compressor unit, such as compressor unit 102 of the above-described embodiment, disposed on a refrigerant path, such as refrigerant path 101 of the above-described embodiment,

The compressor unit includes:

a plurality of compressors (for example, the plurality of coaxial compressors 118 of the above embodiment) disposed in parallel with each other with respect to the refrigerant path;

a plurality of first motors (for example, the plurality of first motors 114A of the above embodiment) for driving the plurality of compressors, respectively;

an expander-integrated compressor (for example, the expander-integrated compressor 120 of the above embodiment) integrally configured with an expander (for example, the expander 103 of the above embodiment) capable of expanding the refrigerant compressed by the compressor unit; and

a second motor (e.g., the second motor 114B of the above embodiment), for driving the expander-integrated compressor,

According to the aspect of (1) above, even when a refrigeration system having different refrigeration capacities is developed, the number of compressors that are part of the compressor unit can be changed to cope with the problem, and therefore, an increase in the number of components and the occupied area associated with the change in design can be favorably suppressed.

(2) In another embodiment, in the embodiment (1) above,

The plurality of first motors and the second motor are common.

According to the aspect of (2) above, the plurality of first motors for driving the plurality of compressors included in the compressor unit are in common with the second motor for driving the expander-integrated compressor. This can reduce the number of types of motors used in the refrigeration system, and effectively reduce the cost and time required for development.

In the present specification, the term "common" to the plurality of first motors and the plurality of second motors means that the plurality of first motors and the plurality of second motors are separate motors, and at least a part of the specifications are common. The specification sharing may mean that at least a part of the output, rotation speed, and size of the motor are the same, or that the motor can be replaced with each other, or that the motor is designed to be identical to each other to such an extent that the assembly of the components other than the motor is not affected.

(3) In another embodiment, in the embodiment (1) or (2) above,

comprises a control device (for example, the control device 200 of the above embodiment) for controlling the plurality of compressors,

at the start-up of the refrigeration system, the control device controls the plurality of compressors in such a manner that a part of the plurality of compressors is operated based on the temperature of the refrigerant at the inlet of the expander.

According to the aspect (3), by operating a part of the plurality of compressors at the time of starting the refrigeration system, the occurrence of surge in the coaxial compressors can be effectively prevented.

(4) In another embodiment, in the embodiment (3) above,

the control device controls the compressors in a start state so as to reduce the rotation speed of the compressors, and then controls the compressors in a start state so as to change the number of the compressors.

According to the aspect (4), when the number of start-up stages of the plurality of compressors is changed, the number of start-up stages can be smoothly changed while preventing surging from occurring in each of the compressors by reducing the rotation speed of the previously started compressors.

(5) In another mode, in any one of the above (1) to (4),

the refrigerant path includes: a bypass line (for example, the second bypass line 170 of the above embodiment) configured to bypass an upstream side and a downstream side of a compressor (for example, the intermediate-stage compressor 110B of the above embodiment) included in the expander-integrated compressor; and

a bypass valve (e.g., the second bypass valve 172 of the above-described embodiment) is disposed on the bypass line.

According to the aspect of (5) above, by adjusting the opening degree of the bypass valve provided in the bypass line, surging in each compressor can be effectively prevented.

(6) In another embodiment, in the embodiment (5) above,

the bypass valve is controlled so that the flow rate of the refrigerant in the compressor of the expander-integrated compressor becomes equal to or greater than a predetermined value, based on the temperature of the refrigerant at the inlet of the expander.

According to the aspect of (6) above, when surge is likely to occur due to an increase in the temperature of the refrigerant at the inlet of the expander, the opening degree of the bypass valve is controlled, and the flow rate of the refrigerant in the compressor included in the expander-integrated compressor is ensured to be equal to or greater than the predetermined value, thereby preventing the occurrence of surge.

(7) In another embodiment, in the embodiment (6) above,

the rotation speed of the compressor or the expander-integrated compressor and the opening degree of the bypass valve are controlled in a coordinated manner so that the cooling rate of the refrigerant becomes substantially constant.

According to the aspect of (7) above, the rotation speed of the compressor or the expander-integrated compressor is controlled in coordination with the opening degree control of the bypass valve, so that the cooling rate of the refrigerant flowing through the refrigerant path is substantially constant. Thus, the cooling rate can be adjusted and corrected during the pre-cooling period from the start-up time to the normal operation time, and the refrigerant temperature can be controlled with high accuracy.

(8) In another mode, in any one of the above (1) to (7),

the plurality of compressors are each a coaxial compressor (for example, the coaxial compressor 118 of the above embodiment) including a plurality of compressors connected in series with respect to the refrigerant path.

According to the aspect of (8), by using the coaxial compressors (multi-stage compressors) as the plurality of compressors, a compression ratio larger than that of the single-stage compressor can be obtained, and high efficiency can be achieved.

Description of the reference numerals

100 refrigeration system

101 refrigerant path

102 compressor unit (110A, 110B, 110C)

103. Expansion machine

104. Cooling part

105. Cold energy recovery heat exchanger

106. Superconducting device

107. Refrigerant path

108. Pump with a pump body

109. Cold box

110. Compressor with a compressor body having a rotor with a rotor shaft

110A low-grade compressor

110B intermediate-stage compressor

110C high-grade compressor

112 (112A, 112B, 112C) heat exchanger

114A first motor

114B second motor

116A, 116B output shaft

118 (118A, 118B) coaxial compressor

120 expander integral type compressor

122-1, 122-2 radial magnetic bearing

126 thrust magnetic bearing

127-1, 127-2 axial turnplate

128. Shell body

130. Motor shell

Impeller shell for 132-1 low-grade compressor

Impeller shell for 132-2 medium-stage compressor

Impeller shell for 132-3 advanced compressor

Impeller shell for 134-1 expander

136A, 136B rotor

138A, 138B stator

140A, 140B, 140C, 142 impeller

144. First pipeline

146A, 146B second pipeline

148A, 148B third pipeline

150. Fourth pipeline

152. Fifth pipeline

154A, 154B sixth pipeline

156A, 156B seventh pipeline

158. Eighth pipeline

160. First valve

162. Second valve

164. Third valve

166. First bypass pipeline

168. First bypass valve

170. Second bypass line

172. Second bypass valve

174. Third bypass line

176. Third bypass valve

178. High pressure refrigerant line

180. Low pressure refrigerant line

182. Fourth bypass pipeline

184. Buffer tank

186. Fourth valve

188. Fifth valve

200. And a control device.

Claims

1. A refrigeration system utilizes a Brayton cycle that generates cold energy using a refrigerant that is compressed by a compressor unit disposed in a refrigerant path,

the compressor unit includes:

A second motor for driving the expander-integrated compressor,

2. A refrigeration system according to claim 1, wherein,

the plurality of first motors and the second motor are common.

3. A refrigeration system according to claim 1 or 2, wherein,

comprises a control device for controlling the plurality of compressors,

4. A refrigeration system according to claim 3, wherein,

5. The refrigeration system according to claim 1 to 4, wherein,

the refrigerant path includes: a bypass line configured to bypass an upstream side and a downstream side of a compressor included in the expander-integrated compressor; and

A bypass valve disposed on the bypass line.

6. The refrigeration system of claim 5, wherein the refrigeration system comprises,

the bypass valve controls a flow rate of the refrigerant in the compressor of the expander-integrated compressor to be equal to or greater than a predetermined value based on a temperature of the refrigerant at an inlet of the expander.

7. The refrigeration system of claim 6, wherein the refrigeration system is configured to store the stored data,

8. The refrigeration system according to any one of claim 1 to 7,

the plurality of compressors are each a coaxial compressor including a plurality of compressors connected in series with respect to the refrigerant path.