Turborefrigerator and method of operation thereof

Abstract

The present application aims to suppress the equipment introduction cost / equipment maintenance cost of a turbo refrigerating machine, to apply a low GWP refrigerant, and to achieve a use temperature exceeding 100℃. A turbo refrigerating machine (1) according to the present application includes a turbo compressor (3) that compresses a refrigerant, a condenser (5) that condenses the refrigerant discharged from the turbo compressor, an expansion valve (7) that expands the refrigerant led out from the condenser, and an evaporator (9) that evaporates the refrigerant led out from the expansion valve, and a refrigerant enclosed in a refrigerant circulation circuit (11) that connects the turbo compressor, the condenser, the expansion valve, and the evaporator in this order is HCFO-1233ydZ, HCFO-1233ydE, or a mixture thereof, and a bearing that supports a rotating shaft (19) of the turbo compressor is a magnetic bearing (21).

Description

Technical Field

[0001] This invention relates to a turbine refrigerator and its operating method. Background Technology

[0002] Regarding the refrigerants used in turbine refrigerators, in recent years, as a measure to address global warming, there has been a push to replace refrigerants with lower global warming potential (GWP) values ​​(Patent Documents 1 and 2).

[0003] Previous technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-73624

[0006] Patent Document 2: International Publication No. 2019 / 039510 Summary of the Invention

[0007] The technical problem to be solved by the invention

[0008] In turbine chillers used in environments containing sophisticated equipment such as data centers, there is a requirement to use chilled water at a temperature of 20°C to 35°C for heat exchange with the refrigerant in the evaporator in order to prevent condensation. Furthermore, in turbine chillers (heat pumps) used in the distillation process of chemical equipment, there is a requirement to use hot water for heat exchange with the refrigerant in the evaporator at a temperature exceeding 40°C.

[0009] Regarding the refrigerant described in Patent Document 1, such as HFO-1234ze(E), its boiling point is relatively low at -19°C. Using such a low-boiling-point refrigerant in a turbine refrigerator would require compliance with the High Pressure Gas Security Act, increasing equipment implementation costs.

[0010] Regarding the refrigerants described in Patent Document 1, such as HCFO-1233zd(E) or HFO-1336mzz(E), whose boiling points are 18°C ​​and 33°C respectively, they do not require compliance with the High Pressure Gas Safety Law. However, in turbine refrigerators using these refrigerants, where cold / hot water at temperatures exceeding 18°C ​​is used in the evaporator's heat exchange, the evaporator pressure becomes above atmospheric pressure. Such turbine refrigerators are subject to the regulations of the Occupational Safety and Health Law.

[0011] Patent Document 2 describes the use of a refrigerant (working medium for heat circulation) mixed with lubricating oil. In turbine refrigeration machines that use lubricating oil, regular maintenance such as bearing replacement, lubricating oil replacement, and oil filter replacement is necessary.

[0012] If the operating temperature of the turbine refrigerator increases, the viscosity of the lubricating oil decreases, and its lubricating performance deteriorates. Therefore, in Patent Document 2, it is difficult to set the operating temperature to exceed 100°C.

[0013] The present invention was made in view of this situation, and its object is to provide a turbine chiller and its operation method that can suppress the cost of equipment introduction.

[0014] The purpose of this invention is to provide a turbine refrigerator and its operation method that can reduce equipment maintenance costs.

[0015] The purpose of this invention is to provide a turbine refrigerator that is suitable for low-GWP refrigerants and can achieve an operating temperature of over 100°C, and its operation method.

[0016] means for solving technical problems

[0017] To address the aforementioned issues, the turbine refrigerator and its operating method of the present invention are implemented in the following manner.

[0018] The turbine refrigerator of the present invention comprises: a turbine compressor for compressing refrigerant; a condenser for condensing the refrigerant ejected from the turbine compressor; an expansion valve for expanding the refrigerant guided from the condenser; and an evaporator for evaporating the refrigerant guided from the expansion valve. The refrigerant sealed in the refrigerant circulation loop formed by sequentially connecting the turbine compressor, the condenser, the expansion valve, and the evaporator is HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof, and the bearing supporting the rotating shaft of the turbine compressor is a magnetic bearing.

[0019] In the method of operating the turbine refrigerator according to the present invention, the turbine refrigerator comprises: a turbine compressor for compressing refrigerant; a condenser for condensing the refrigerant ejected from the turbine compressor; an expansion valve for expanding the refrigerant guided from the condenser; an evaporator for evaporating the refrigerant guided from the expansion valve; a refrigerant circulation loop sequentially connected to the turbine compressor, the condenser, the expansion valve, and the evaporator; a magnetic bearing for supporting the rotating shaft of the turbine compressor; and a heat exchange path through which a heat exchange medium that exchanges heat with the refrigerant in the evaporator passes. In the method of operating the turbine refrigerator, HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof are sealed into the refrigerant circulation loop as refrigerant, and the heat exchange medium at a temperature exceeding 40°C is supplied to the heat exchange path.

[0020] In the method of operating the turbine refrigerator according to the present invention, the turbine refrigerator comprises: a turbine compressor for compressing refrigerant; a condenser for condensing the refrigerant injected from the turbine compressor; an expansion valve for expanding the refrigerant guided from the condenser; an evaporator for evaporating the refrigerant guided from the expansion valve; a refrigerant circulation loop sequentially connected to the turbine compressor, the condenser, the expansion valve, and the evaporator; and a heat exchange path through which a heat exchange medium for heat exchange with the refrigerant in the evaporator passes. In the method of operating the turbine refrigerator, HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof are sealed into the refrigerant circulation loop as refrigerant, and the temperature of the heat exchange medium at the outlet of the heat exchange path is managed to be below 48°C.

[0021] Invention Effects

[0022] According to the present invention, by making the bearing supporting the rotating shaft of the turbo compressor a magnetic bearing, no lubricating oil is required, thus reducing equipment maintenance costs.

[0023] According to the present invention, by using HCFO-1233yd(Z), HCFO-1233yd(E) or a mixture thereof as a refrigerant, it is possible to suppress equipment implementation costs.

[0024] According to the present invention, a turbine refrigerator is available that is suitable for low-GWP refrigerants and can achieve an operating temperature of over 100°C. Attached Figure Description

[0025] Figure 1 This is a schematic structural diagram illustrating a turbine refrigerator according to an embodiment of the present invention. Detailed Implementation

[0026] Hereinafter, with reference to the accompanying drawings, one embodiment of the turbine refrigerator and its operating method according to the present invention will be described.

[0027] In this specification, "turbo compressor" is a general term for either a refrigeration machine equipped with a turbo compressor or a heat pump equipped with a turbo compressor.

[0028] Figure 1 The diagram shows a schematic structural diagram of the turbine refrigerator according to this embodiment.

[0029] The turbine refrigerator 1 includes: a turbine compressor 3 for compressing refrigerant; a condenser 5 for condensing the refrigerant compressed by the turbine compressor 3; an expansion valve 7 for expanding the refrigerant condensed by the condenser 5; and an evaporator 9 for evaporating the refrigerant expanded by the expansion valve 7.

[0030] The turbine refrigerator 1 has a refrigerant circulation loop 11 consisting of a turbine compressor 3, a condenser 5, an expansion valve 7 and an evaporator 9 connected in sequence.

[0031] A refrigerant is sealed within the refrigerant circulation loop 11. The refrigerant is HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof. HCFO-1233yd(Z) has a boiling point of 54°C, and HCFO-1233yd(E) has a boiling point of 48°C. Their global warming potential (GWP) is less than 1.

[0032] The turbo compressor 3 is a centrifugal two-stage compressor with two impellers 13a and 13b, driven by an electric motor 15 whose speed is controlled by an inverter device (not shown). The output of the inverter device is controlled by a control unit (not shown). Furthermore, the number of impellers is not limited; a single impeller can be used for a one-stage compressor.

[0033] The impellers 13a and 13b of the turbo compressor 3 are equipped with inlet guide vanes (not shown) to control the flow rate of the intake refrigerant, which enables capacity control of the turbo compressor 1.

[0034] The turbo compressor 3 and the electric motor 15 are housed in a sealed manner within the housing 17. The housing 17 is made of a metal such as an aluminum alloy. The housing 17 can be opened and closed for maintenance and other purposes.

[0035] The rotating shaft 19 of the turbo compressor 3 is supported by a magnetic bearing 21 for free rotation. By using the magnetic bearing 21, the lubrication system can be eliminated. Since there is no need to replace the bearings or lubricating oil, equipment maintenance costs can be reduced.

[0036] A first radial magnetic bearing coil 21a of a magnetic bearing 21 is provided on the impeller 13a, 13b side of the electric motor 15, and a second radial magnetic bearing coil 21b of a magnetic bearing 21 is provided on the side of the electric motor 15 opposite to the impeller 13a, 13b. The radial direction of the rotating shaft 19 is supported by the first radial magnetic bearing coil 21a and the second radial magnetic bearing coil 21b.

[0037] Alternatively, although the illustration is omitted, a circular plate can be fixed to the end of the rotating shaft 19 on the side opposite to the impellers 13a and 13b (the side of the second radial magnetic bearing coil 21b), and multiple pairs of thrust magnetic bearing coils can be arranged on both sides of the circular plate. The thrust direction can be positioned while the circular plate is floating due to the multiple pairs of thrust magnetic bearing coils. This allows for accurate determination of the thrust direction of the rotating shaft 19 and the impellers 13a and 13b.

[0038] The electric motor 15 includes a rotor 23 that rotates around a central axis and a generally cylindrical stator 25 arranged around the rotor 23 with a predetermined gap. The rotational output of the rotor 23 is transmitted to the impellers 13a and 13b via a rotating shaft 19.

[0039] The condenser 5 is a heat exchanger that condenses the high-temperature, high-pressure gaseous refrigerant drawn from the turbo compressor 3. The condenser 5 internally has a first heat exchange path 27. The first heat exchange path 27 can be, for example, a heat transfer tube inserted through the condenser 5.

[0040] In the condenser 5, heat exchange occurs between the (gas) refrigerant guided from the turbo compressor 3 and the first heat exchange medium M1 flowing within the first heat exchange path 27. Through this heat exchange, the refrigerant is cooled, and the first heat exchange medium M1 is heated.

[0041] The heated first heat exchange medium M1 flows toward the outside of the condenser 5 in the first heat exchange path 27, and after exhausting its waste heat in a cooling tower (not shown), it is guided back to the condenser 5. The flow of the refrigerant supplied to the condenser 5 and the flow of the first heat exchange medium M1 supplied to the first heat exchange path 27 are preferably arranged to be countercurrent.

[0042] In expansion valve 7, the liquid refrigerant condensed by condenser 5 is expanded.

[0043] Evaporator 9 is a heat exchanger that evaporates the liquid refrigerant expanded by expansion valve 7. Evaporator 9 has a second heat exchange path 29 inside. The second heat exchange path 29 may be, for example, a heat transfer tube inserted through evaporator 9.

[0044] In the evaporator 9, heat exchange occurs between the (liquid) refrigerant expanded by the expansion valve 7 and the second heat exchange medium M2 flowing in the second heat exchange path 29. Through this heat exchange, the refrigerant is heated and evaporated, and the second heat exchange medium M2 is cooled.

[0045] The cooled second heat exchange medium M2 flows toward the outside of the evaporator 9 in the second heat exchange path 29 and is introduced into a device (not shown) located outside the turbine refrigerator 1 to be heated. The second fluid heated in the device outside the evaporator 9 flows back into the second heat exchange path 29 and exchanges heat with the refrigerant again in the evaporator 9.

[0046] The temperature (evaporator inlet temperature) of the second heat exchange medium M2 at the inlet of the second heat exchange path 29 is designed to exceed 40°C. In this turbine refrigerator 1, other waste heat can be utilized as the second heat exchange medium M2. This turbine refrigerator 1 is also suitable for use in areas with high outside air temperatures.

[0047] When the turbine refrigerator 1 is a heat pump, the refrigerant absorbs heat from the heat source in the evaporator 9 and releases that heat in the condenser 5. By operating the system in a manner that supplies a second heat exchange medium (heat source water) M2 exceeding 40°C to the second heat exchange path 29 of the evaporator 9, the amount of heat released in the condenser 5 can be increased.

[0048] The temperature of the second heat exchange medium M2 at the outlet of the second heat exchange path 29 (evaporator outlet temperature) can be below 48°C. By operating the evaporator 9 in a manner that maintains the outlet temperature of the second heat exchange medium M2 below 48°C, the pressure inside the evaporator 9 can be kept below atmospheric pressure. This turbine refrigerator 1 does not require compliance with occupational safety and health regulations, thus reducing equipment implementation costs.

[0049] <Postscript>

[0050] The turbine refrigerator and its operation method described in the above-described embodiments can be understood as follows.

[0051] The turbine refrigerator 1 according to the first aspect of the present invention includes: a turbine compressor 3 for compressing refrigerant; a condenser 5 for condensing the refrigerant ejected from the turbine compressor; an expansion valve 7 for expanding the refrigerant guided from the condenser; and an evaporator 9 for evaporating the refrigerant guided from the expansion valve. The refrigerant sealed in the refrigerant circulation loop 11 formed by sequentially connecting the turbine compressor, the condenser, the expansion valve, and the evaporator is HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof, and the bearing supporting the rotating shaft 19 of the turbine compressor is a magnetic bearing 21.

[0052] By using magnetic bearings to support the rotating shaft of the turbo compressor, no lubrication is required. In turbo refrigeration units that do not use lubrication, there is no need to change the lubricating oil, thus reducing equipment maintenance.

[0053] If the operating temperature of the turbine refrigerator becomes high, the viscosity of the lubricating oil decreases, and its lubrication performance declines. In the turbine refrigerator of this invention, no lubricating oil is used; therefore, the operating temperature of the turbine refrigerator can be set without being limited by the type of lubricating oil.

[0054] HCFO-1233yd(Z), HCFO-1233yd(E), or mixtures thereof have a global warming potential (GWP) of less than 1, and therefore have a low environmental impact.

[0055] HCFO-1233yd(Z), HCFO-1233yd(E), or mixtures thereof have boiling points above 48°C. When these refrigerants are used in turbine refrigerators, the High Pressure Gas Safety Law does not apply. Therefore, compared to turbine refrigerators using refrigerants such as HFO-1234yf, which require the High Pressure Gas Safety Law, equipment implementation costs can be reduced.

[0056] According to the above invention, a heat pump with an operating temperature exceeding 100°C can be realized using a low-GWP refrigerant.

[0057] In the turbine refrigerator according to the second aspect of the present invention, the evaporator in the first aspect has a heat exchange path (second heat exchange path 29) inside for the flow of a heat exchange medium (second heat exchange medium M2) for heat exchange with the refrigerant, and the temperature of the heat exchange medium at the inlet of the heat exchange path exceeds 40°C.

[0058] If the temperature of the heat exchange medium exceeds 40°C, the temperature of the evaporator will also exceed 40°C. In turbine refrigeration machines using magnetic bearings, no lubricating oil is used, so even if the temperature inside the evaporator exceeds 40°C, the decrease in the viscosity of the lubricating oil will not be a problem.

[0059] In the turbine refrigerator according to the third aspect of the present invention, the evaporator in the first aspect described above has a heat exchange path inside for the flow of a heat exchange medium that exchanges heat with the refrigerant, and the temperature of the heat exchange medium at the outlet of the heat exchange path is below 48°C.

[0060] By setting the temperature of the heat exchange medium at the outlet of the heat exchange path to a temperature lower than the boiling point of the refrigerant (below 48°C), the evaporator pressure can be lower than atmospheric pressure. Therefore, occupational safety and health regulations are not required, thus reducing equipment implementation costs.

[0061] In the method of operating a turbine refrigerator according to the fourth aspect of the present invention, the turbine refrigerator includes: a turbine compressor for compressing a refrigerant; a condenser for condensing the refrigerant ejected from the turbine compressor; an expansion valve for expanding the refrigerant guided from the condenser; an evaporator for evaporating the refrigerant guided from the expansion valve; a refrigerant circulation loop sequentially connected to the turbine compressor, the condenser, the expansion valve, and the evaporator; a magnetic bearing for supporting the rotating shaft of the turbine compressor; and a heat exchange path through which a heat exchange medium that exchanges heat with the refrigerant in the evaporator passes. In the method of operating the turbine refrigerator, HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof are sealed into the refrigerant circulation loop as a refrigerant, and the heat exchange medium at a temperature exceeding 40°C is supplied to the heat exchange path.

[0062] In the fifth aspect of the present invention, the turbine refrigerator includes: a turbine compressor for compressing a refrigerant; a condenser for condensing the refrigerant ejected from the turbine compressor; an expansion valve for expanding the refrigerant guided from the condenser; an evaporator for evaporating the refrigerant guided from the expansion valve; a refrigerant circulation loop sequentially connected to the turbine compressor, the condenser, the expansion valve, and the evaporator; and a heat exchange path through which a heat exchange medium that exchanges heat with the refrigerant in the evaporator passes. In the method of operating the turbine refrigerator, HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof are sealed into the refrigerant circulation loop as a refrigerant, and the temperature of the heat exchange medium at the outlet of the heat exchange path is maintained below 48°C.

[0063] Symbol explanation:

[0064] 1-Turbine refrigeration unit, 3-Turbine compressor, 5-Condenser, 7-Expansion valve, 9-Evaporator, 11-Refrigerant circulation loop, 13a, 13b-Impeller, 15-Electric motor, 17-Housing, 19-Rotating shaft, 21-Magnetic bearing, 21a-First radial magnetic bearing coil, 21b-Second radial magnetic bearing coil, 23-Rotor, 25-Stator, 27-First heat exchange path, 29-Second heat exchange path (heat exchange path).

Claims

1. A turbine refrigerator comprising: a turbine compressor for compressing a refrigerant; a condenser for condensing the refrigerant injected from the turbine compressor; an expansion valve for expanding the refrigerant directed from the condenser; and an evaporator for evaporating the refrigerant directed from the expansion valve. The refrigerant sealed into the refrigerant circulation loop formed by the turbine compressor, the condenser, the expansion valve and the evaporator connected in sequence is HCFO-1233yd(Z), HCFO-1233yd(E) or a mixture thereof. The bearing supporting the rotating shaft of the turbo compressor is a magnetic bearing.

2. The turbine refrigerator according to claim 1, wherein, The evaporator has an internal heat exchange path for the flow of a heat exchange medium that exchanges heat with the refrigerant. The temperature of the heat exchange medium at the inlet of the heat exchange path exceeds 40°C.

3. The turbine refrigerator according to claim 1, wherein, The evaporator has an internal heat exchange path for the flow of a heat exchange medium that exchanges heat with the refrigerant. The temperature of the heat exchange medium at the outlet of the heat exchange path is below 48°C.

4. A method for operating a turbine refrigerator, the turbine refrigerator comprising: a turbine compressor for compressing refrigerant; A condenser condenses the refrigerant ejected from the turbo compressor; an expansion valve expands the refrigerant drawn from the condenser; an evaporator evaporates the refrigerant drawn from the expansion valve; a refrigerant circulation loop is formed by sequentially connecting the turbo compressor, the condenser, the expansion valve, and the evaporator; and a magnetic bearing supports the rotating shaft of the turbo compressor. and a heat exchange path through which the heat exchange medium that exchanges heat with the refrigerant in the evaporator passes. In the operation method of the turbine refrigerator, HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof are introduced into the refrigerant circulation loop as a refrigerant. The heat exchange medium at a temperature exceeding 40°C is supplied to the heat exchange path.

5. A method of operating a turbo refrigerator, the turbo refrigerator comprising: a turbo compressor for compressing refrigerant; a condenser for condensing the refrigerant injected from the turbo compressor; an expansion valve for expanding the refrigerant guided from the condenser; an evaporator for evaporating the refrigerant guided from the expansion valve; a refrigerant circulation loop sequentially connected to the turbo compressor, the condenser, the expansion valve, and the evaporator; and a heat exchange path through which a heat exchange medium for heat exchange with the refrigerant in the evaporator passes. In the operation method of the turbine refrigerator, HCFO-1233yd(Z), HCFO-1233yd(E), or a mixture thereof are introduced into the refrigerant circulation loop as a refrigerant. The temperature of the heat exchange medium at the outlet of the heat exchange path is managed to be below 48°C.

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