WO2020195816A1

WO2020195816A1 - Turbo refrigerator

Info

Publication number: WO2020195816A1
Application number: PCT/JP2020/010470
Authority: WO
Inventors: 長谷川　泰士; 八幡　直樹; 毅金子
Original assignee: 三菱重工サーマルシステムズ株式会社
Priority date: 2019-03-26
Filing date: 2020-03-11
Publication date: 2020-10-01
Also published as: JP2020159263A; JP7271254B2; CN113597515A

Abstract

Provided is a turbo refrigerator capable of suppressing air loss generated in a rotary shaft of a turbo compressor and acquiring a cooling amount necessary for cooling magnetic a bearing which supports the rotary shaft. A turbo compressor (3) is provided with: an impeller; a rotary shaft (24) that rotates the impeller; a magnetic bearing (30) that supports the rotary shaft (24); a gas refrigerant supply pipe (14) through which a gas refrigerant is supplied as a cooling medium to magnetic bearing coils (30a), (30b) from a condenser which is a high-pressure part and which is on the upstream side of an expansion valve in a refrigeration cycle; and a refrigerant return pipe through which the gas refrigerant having passed through the magnetic bearing coils (30a), (30b) is guided to an evaporator which is a low-pressure part on the downstream side of the expansion valve in the refrigeration cycle.

Description

Centrifugal chiller

The present invention relates to a turbo chiller including a turbo compressor having a rotating shaft supported by magnetic bearings.

Magnetic bearings are applied to reduce mechanical loss of centrifugal compressors and eliminate lubricating oil systems. In addition to the above-mentioned merits, the turbo chiller is also applied to reduce the life cycle cost by reducing the periodic maintenance items (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-33348

The magnetic bearing is equipped with a coil part through which an electric current flows, and the coil part generates heat when the electric current flows. Since the magnetic bearing supports the rotating shaft that rotates at high speed with a minute gap, wind loss occurs as a stirring loss in this minute gap. It is desirable to cool the coil portion to prevent overheating. The cooling efficiency is higher when a liquid refrigerant having a large heat capacity is used for cooling. However, when a liquid having a high density is supplied to the minute gaps, there are problems that wind damage increases, resulting in a decrease in the efficiency of the turbo chiller and hindering stable support of the magnetic bearing.

In Patent Document 1, a liquid refrigerant is supplied to a ceramic bearing for cooling, but unlike a ceramic bearing, the magnetic bearing does not generate heat due to sliding friction, so that cooling of the magnetic bearing is disclosed. Absent. It is disclosed that the gas refrigerant is supplied to the ceramic bearing, but since the low-pressure gas refrigerant evaporated by the evaporator is used, there is a possibility that the gas refrigerant required for cooling cannot be supplied. There is.

The present invention has been made in view of such circumstances, and the amount of cooling required to suppress wind damage generated on the rotating shaft of the turbo compressor and to cool the magnetic bearing supporting the rotating shaft. It is an object of the present invention to provide a turbo chiller capable of obtaining.

The turbo refrigerator according to one aspect of the present invention includes a turbo compressor that compresses the refrigerant, a condenser that condenses the refrigerant discharged from the turbo compressor, and an expansion that expands the liquid refrigerant derived from the condenser. The turbo compressor includes a refrigeration cycle including a valve and an evaporator for evaporating the refrigerant derived from the expansion valve, and the turbo compressor supports an impeller, a rotating shaft for rotating the impeller, and the rotating shaft. The magnetic bearing, the gas refrigerant supply path that supplies the gas refrigerant as a cooling medium from the high-pressure portion on the upstream side of the refrigeration cycle to the magnetic bearing, and the gas refrigerant after passing through the magnetic bearing. It is provided with a gas refrigerant return path leading to a low pressure portion on the downstream side of the refrigeration cycle with respect to the expansion valve.

Since the gas refrigerant is supplied to the magnetic bearing from the gas refrigerant supply path as a cooling medium without being heated by another heating element such as an electric motor, the magnetic bearing can be effectively cooled. Since a gas refrigerant is used as the cooling medium instead of a liquid refrigerant, wind damage generated on the rotating shaft can be suppressed.
Through the gas refrigerant return path, the gas refrigerant as a cooling medium is guided from the high-pressure portion on the upstream side of the expansion valve to the magnetic bearing and returned to the low-pressure portion on the downstream side of the expansion valve. As a result, the cooling refrigerant gas can be supplied by effectively utilizing the difference in high and low pressure of the refrigeration cycle, so that the gas refrigerant can be easily used as the cooling medium.

Further, in the turbo chiller according to one aspect of the present invention, the gas refrigerant supplied from the gas refrigerant supply path passes between the magnetic bearing and the rotating shaft.

Since the gas refrigerant supplied from the gas refrigerant supply path passes between the magnetic bearing and the rotating shaft, wind damage between the magnetic bearing and the rotating shaft can be suppressed.

Further, in the turbo chiller according to one aspect of the present invention, the gas refrigerant supply path is connected to an axial gas refrigerant supply hole formed in the axial direction of the rotating shaft and the axial gas refrigerant supply hole. It also includes a radial gas refrigerant supply hole formed on the outer side in the radial direction toward the magnetic bearing side.

It was decided that the gas refrigerant would flow in the axial direction of the rotating shaft through the axial gas refrigerant supply hole, and the gas refrigerant would flow radially outward toward the magnetic bearing side through the radial gas refrigerant supply hole. By supplying the gas refrigerant from the rotating shaft side in this way, the configuration can be simplified. The gas refrigerant can be supplied from the radial gas refrigerant supply hole by utilizing the centrifugal force of the rotating shaft. As a result, the gas refrigerant can be reliably supplied even under the operating conditions where the height difference pressure of the turbo chiller is low.

Further, in the turbo chiller according to one aspect of the present invention, a holding portion for holding the magnetic bearing, an auxiliary bearing fixed to the holding portion and provided on the side of the magnetic bearing, and the holding portion. , The gas refrigerant is supplied from the gas refrigerant supply path to the space surrounded by the magnetic bearing and the auxiliary bearing.

It was decided to supply the gas refrigerant from the gas refrigerant supply path to the space surrounded by the holding portion for holding the magnetic bearing, the magnetic bearing, and the auxiliary bearing. By supplying the gas refrigerant to the space surrounded in this way, the gas refrigerant can be first supplied to the side of the magnetic bearing, and then the gas refrigerant can flow between the magnetic bearing and the rotating shaft. As a result, the gas refrigerant can be reliably supplied around the magnetic bearing, and the cooling efficiency can be improved.
The auxiliary bearing comes into contact with the rotating shaft and rotatably supports the rotating shaft when the magnetic bearing cannot be driven due to a trouble or the like. As the auxiliary bearing, for example, a ball bearing can be used.

Further, the turbo chiller according to one aspect of the present invention includes a casing cooling unit in which a cooling medium is supplied to the casing accommodating the turbo compressor.

The casing of the turbo compressor is cooled by the casing cooling section to which the cooling medium is supplied. The heat generated by the magnetic bearing is conducted to the casing and cooled by the casing cooling unit. By using the casing as a heat sink in this way, the cooling capacity of the magnetic bearing can be increased.
As the cooling medium supplied to the casing cooling unit, for example, a liquid refrigerant derived from the refrigerant cycle or cooling water supplied from the outside can be used.

Since the magnetic bearing is cooled by the gas refrigerant, it is possible to suppress wind damage generated on the rotating shaft of the turbo compressor and obtain the amount of cooling required to cool the magnetic bearing supporting the rotating shaft. ..

It is a schematic block diagram of the turbo chiller which concerns on 1st Embodiment of this invention. It is a vertical sectional view of the turbo compressor of FIG. It is a schematic block diagram which showed the modification of FIG. It is a vertical sectional view which showed the turbo compressor of the turbo chiller which concerns on 2nd Embodiment of this invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
[First Embodiment]

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of the turbo chiller 1.
The turbo chiller 1 includes a turbo compressor 3 that compresses a refrigerant, a condenser 5 that condenses a high-temperature and high-pressure gas refrigerant compressed by the turbo compressor 3, and an expansion valve 7 that expands a liquid refrigerant from the condenser 5. And an evaporator 9 that evaporates the liquid refrigerant expanded by the expansion valve 7.

The turbo compressor 3 is a centrifugal two-stage compressor provided with two

impellers

13a and 13b, and is driven by an electric motor 10 whose rotation speed is controlled by an inverter device (not shown). The output of the inverter device is controlled by a control unit (not shown). The number of impellers is not limited, and one impeller may be used as a one-stage compressor.

Inlet guide vanes (not shown) for controlling the flow rate of the intake refrigerant are provided at the refrigerant suction ports of the

impellers

13a and 13b of the turbo compressor 3, and the capacity of the turbo chiller 1 can be controlled. ..

The turbo compressor 3 and the electric motor 10 are housed in a sealed casing 12. The casing 12 is made of a metal having a high thermal conductivity, for example, a metal such as an aluminum alloy.

The electric motor 10 includes a rotor 20 that rotates around a central axis, and a substantially cylindrical stator 22 that is provided with a predetermined gap around the rotor 20. The rotational output of the rotor 20 is transmitted to the

impellers

13a and 13b via the rotary shaft (rotary shaft) 24.

In the condenser 5, the high-temperature and high-pressure refrigerant derived from the turbo compressor 3 is condensed. A cooling heat transfer tube 26 through which cooling water for cooling the refrigerant flows is inserted in the condenser 5. The cooling water is exhausted to the outside in a cooling tower (not shown), and then is guided to the condenser 5 again.

The refrigerant squeezed by the expansion valve 7 is guided to the evaporator 9 and evaporates internally. By endothermic in the evaporator 9, cold water having a rated temperature (for example, 7 ° C.) is obtained. A chilled water heat transfer tube 28 for cooling the chilled water supplied to the external load is inserted in the evaporator 9.

A liquid refrigerant supply pipe 14 is provided between the lower portion (for example, the bottom portion) of the condenser 5 and the casing 12. The liquid refrigerant stored in the lower part of the condenser 5 is guided to the casing 12 side via the liquid refrigerant supply pipe 14. Although not shown, a flow rate adjusting valve for adjusting the flow rate of the liquid refrigerant may be provided in the liquid refrigerant supply pipe 14.

As shown in FIG. 1, a gas refrigerant supply pipe (gas refrigerant supply path) 16 is provided between the upper portion of the condenser 5 and the casing 12. The gas refrigerant existing in the upper part of the condenser 5 is guided to the casing 12 side through the gas refrigerant supply pipe 16. Although not shown, a flow rate adjusting valve for adjusting the flow rate of the gas refrigerant may be provided in the gas refrigerant supply pipe 16. The downstream end of the gas refrigerant supply pipe 16 is connected to the end portion (right end portion in FIG. 1) of the casing 12 on the side opposite to the

impellers

13a and 13b.

A refrigerant return pipe (gas refrigerant return path) 18 is provided between the upper part of the evaporator 9 and the casing 12. The refrigerant in the casing 12 is guided to the upper part of the evaporator 9 through the refrigerant return pipe 18.

FIG. 2 shows the specific configuration of the turbo compressor 3. The rotary shaft 24 of the turbo compressor 3 is rotatably supported by a magnetic bearing 30.

The first radial magnetic bearing coil 30a of the magnetic bearing 30 is provided on the

impellers

13a and 13b sides of the electric motor 10, and the second magnetic bearing 30 is provided on the side opposite to the

impellers

13a and 13b of the electric motor 10. A radial magnetic bearing coil 30b is provided. The radial direction of the rotary shaft 24 is supported by the first radial magnetic bearing coil 30a and the second radial magnetic bearing coil 30b.

The first radial magnetic bearing coil 30a is fixed and held on the inner peripheral side of the first holding portion 44a fixed to the casing 12. The first holding portion 44a is made of a metal having good thermal conductivity, for example, a metal such as an aluminum alloy.
The second radial magnetic bearing coil 30b is fixed and held on the inner peripheral side of the second holding portion 44b fixed to the casing 12. The second holding portion 44b is made of a metal having good thermal conductivity, for example, a metal such as an aluminum alloy.

On the electric motor 10 side of the first radial magnetic bearing coil 30a, a first gap sensor G1 for measuring the distance (gap) between the rotating shaft 24 and the first radial magnetic bearing coil 30a is provided. The output of the first gap sensor G1 is sent to the control unit.
On the electric motor 10 side of the second radial magnetic bearing coil 30b, a second gap sensor G2 for measuring the distance (gap) between the rotating shaft 24 and the second radial magnetic bearing coil 30b is provided. The output of the second gap sensor G2 is sent to the control unit.

A first auxiliary bearing (auxiliary bearing) 32a is provided between the first radial magnetic bearing coil 30a and the

impellers

13a and 13b. A second auxiliary bearing 32b (auxiliary bearing) is provided on the side of the second radial magnetic bearing coil 30b opposite to the

impellers

13a and 13b. The first auxiliary bearing 32a and the second auxiliary bearing 32b are, for example, ball bearings, and when the magnetic bearing 30 is normally driven, a predetermined clearance is provided with respect to the rotating shaft 24. These

auxiliary bearings

32a and 32b come into contact with the rotary shaft 24 and rotatably support the magnetic bearing 30 when the magnetic bearing 30 cannot be driven due to a trouble or the like.

The first auxiliary bearing 32a is fixed and held on the inner peripheral side of the first holding portion 44a. The first auxiliary bearing 32a and the first radial magnetic bearing coil 30a are separated from each other, and a first space S1 is formed on the inner peripheral side of the first holding portion 44a.
The second auxiliary bearing 32b is fixed and held by the second holding portion 44b. The second auxiliary bearing 32b and the second radial magnetic bearing coil 30b are separated from each other, and a second space S2 is formed on the inner peripheral side of the second holding portion 44b.

A disk 24a is fixed to the end (right end in FIG. 2) of the rotating shaft 24 opposite to the

impellers

13a and 13b. A plurality of pairs of thrust magnetic bearing coils 30c are provided on both sides of the disk 24a. Positioning in the thrust direction is performed with the disk 24a floating by the plurality of pairs of thrust magnetic bearing coils 30c. As a result, the positions of the rotating shaft 24 and the

impellers

13a and 13b in the thrust direction can be accurately determined.

As shown in FIG. 2, the gas refrigerant supplied from the gas refrigerant supply pipe 16 is guided to the axial gas refrigerant supply hole 17a formed in the central axis direction of the rotating shaft 24. The axial gas refrigerant supply hole 17a is formed from the rear end (right end in FIG. 2) of the rotary shaft 24 to the front of the

impellers

13a and 13b (more specifically, the first radial magnetic bearing coil 30a and the first auxiliary bearing 32a). It is formed over the position corresponding to the space.

Radial gas refrigerant supply holes 17b1 and 17b2 formed toward the outer side in the radial direction of the rotary shaft 24 are connected to the axial gas refrigerant supply hole 17a.

The first radial gas refrigerant supply hole 17b1 formed on the

impellers

13a and 13b side of the electric motor 10 is provided at a position corresponding to the first radial magnetic bearing coil 30a. Specifically, the outlet of the first radial gas refrigerant supply hole 17b1 opens in the first space S1 surrounded by the first radial magnetic bearing coil 30a, the first holding portion 44a, and the first auxiliary bearing holding portion 45a. are doing. As a result, the gas refrigerant is supplied into the first space S1 from the first radial gas refrigerant supply hole 17b1 to cool the side surface of the first radial magnetic bearing coil 30a, and the first radial magnetic bearing coil 30a and the rotary shaft 24. The first radial magnetic bearing coil 30a is cooled while the gas refrigerant passes between the two. The cooled gas refrigerant is discharged from the first refrigerant return pipe (gas refrigerant return path) 18a to the outside of the casing 12.

The second radial gas refrigerant supply hole 17b2 formed on the side opposite to the

impellers

13a and 13b of the electric motor 10 is provided at a position corresponding to the second radial magnetic bearing coil 30b. Specifically, the outlet of the second radial gas refrigerant supply hole 17b2 is opened in the second space S2 surrounded by the second radial magnetic bearing coil 30b, the second holding portion 44b, and the second auxiliary bearing 32b. There is. As a result, the gas refrigerant is supplied into the second space S2 from the second radial gas refrigerant supply hole 17b2 to cool the side surface of the second radial magnetic bearing coil 30b, and the second radial magnetic bearing coil 30b and the rotary shaft 24. The second radial magnetic bearing coil 30b is cooled while the gas refrigerant passes between the two. The cooled gas refrigerant is discharged from the first refrigerant return pipe 18a to the outside of the casing 12.

The downstream end of the liquid refrigerant supply pipe 14 is connected to a cooling jacket (casing cooling portion) 15 provided on the casing 12. The cooling jacket 15 is provided around the stator 22 and has a space through which the liquid refrigerant flows. The cooling jacket 15 is provided along the axial direction of the stator 22. The cooling jacket 15 cools not only the stator 22 but also the casing 12 in the vicinity of the cooling jacket 15 by heat conduction.
The refrigerant that has flowed through the cooling jacket 15 and cooled the stator 22 is discharged from the second refrigerant return pipe 18b to the outside of the casing 12.

The control unit is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a computer-readable storage medium, and the like. As an example, a series of processes for realizing various functions are stored in a storage medium or the like in the form of a program, and the CPU reads this program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program may be pre-installed in a ROM or other storage medium, provided in a state of being stored in a computer-readable storage medium, or distributed via a wired or wireless communication means. May be applied. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

<Operation of turbo chiller 1>
Next, the operation of the turbo chiller 1 having the above configuration will be described.
The turbo compressor 3 sucks in the gas refrigerant from the evaporator 9 and compresses it with the

impellers

13a and 13b. The compressed gas refrigerant is sent to the condenser 5, and is condensed by removing the heat of condensation by the cooling heat transfer tube 26. The liquid refrigerant after condensation flows to the expansion valve 7.
The liquid refrigerant that has flowed to the expansion valve 7 is expanded by the expansion valve 7 and then sent to the evaporator 9. In the evaporator 9, the liquid refrigerant evaporates and vaporizes by removing the latent heat of vaporization from the cold water flowing in the cold water heat transfer tube 28. The cold water cooled in this way is sent to an external load (not shown). The gas refrigerant vaporized in the evaporator 9 is sent to the turbo compressor 3 again.

<Gas refrigerant cooling>
Cooling by the gas refrigerant led from the gas refrigerant supply pipe 16 to the turbo compressor 3 is performed as follows.
High-pressure gas refrigerant is sent from the condenser 5 to the axial gas refrigerant supply hole 17a formed in the rotating shaft 24 via the gas refrigerant supply pipe 16. The gas refrigerant that has flowed through the axial gas refrigerant supply hole 17a is guided to the first space S1 via the first radial gas refrigerant supply hole 17b1, and is guided to the first space S1 through the second radial gas refrigerant supply hole 17b2. It is led to S2. The gas refrigerant passes through the first space S1 and passes between the first radial magnetic bearing coil 30a and the rotating shaft 24 to cool the first radial magnetic bearing coil 30a. The gas refrigerant passes through the second space S2 and passes between the second radial magnetic bearing coil 30b and the rotating shaft 24 to cool the second radial magnetic bearing coil 30b.
The gas refrigerant having cooled the

magnetic bearing coils

30a and 30b is returned to the evaporator 9 having a low pressure via the first refrigerant return pipe 18a.

<Liquid refrigerant cooling>
Cooling by the liquid refrigerant led from the liquid refrigerant supply pipe 14 to the turbo compressor 3 is performed as follows.
High-pressure liquid refrigerant is sent from the condenser 5 to the cooling jacket 15 provided in the casing 12 via the liquid refrigerant supply pipe 14. The liquid refrigerant that has flowed into the cooling jacket 15 takes heat from the stator 22 and cools the electric motor 10. At the same time, since the casing 12 is also cooled by the refrigerant, the first radial magnetic bearing coil 30a held by the first holding portion 44a and the second radial magnetic bearing coil 30b held by the second holding portion 44b are also cooled. ..
The refrigerant that has been cooled by the cooling jacket 15 is returned to the evaporator 9 having a low pressure via the second refrigerant return pipe 18b.

According to this embodiment, the following actions and effects are exhibited.
Since the gas refrigerant is supplied from the gas refrigerant supply pipe 16 to the

magnetic bearing coils

30a and 30b as a cooling medium, the

magnetic bearing coils

30a and 30b can be effectively cooled. Since a gas refrigerant is used as the cooling medium instead of a liquid refrigerant, wind damage caused by the rotating shaft 24 can be suppressed.
The first refrigerant return pipe 18a guides the gas refrigerant as a cooling medium from the condenser 5 which is a high pressure portion on the upstream side of the expansion valve 7 to the

magnetic bearing coils

30a and 30b, and lower pressure on the downstream side of the expansion valve 7. It was decided to return it to the evaporator 9 which is a part. As a result, the difference between high and low pressure in the refrigeration cycle can be effectively used, so that the gas refrigerant can be easily used as a cooling medium.

Since the gas refrigerant supplied from the gas refrigerant supply pipe 16 passes between the

magnetic bearing coils

30a and 30b and the rotary shaft 24, wind damage between the

magnetic bearing coils

30a and 30b and the rotary shaft 24 can be suppressed. Can be done.

The axial gas refrigerant supply hole 17a allows the gas refrigerant to flow in the axial direction of the rotating shaft 24, and the radial gas refrigerant supply holes 17b1 and 17b2 allow the gas refrigerant to flow radially outward toward the

magnetic bearing coils

30a and 30b. And said. In this way, by supplying the gas refrigerant from the rotary shaft 24 side, the configuration can be simplified. Gas refrigerant can be supplied from the radial gas refrigerant supply holes 17b1 and 17b2 by utilizing the centrifugal force of the rotary shaft 24. As a result, the gas refrigerant can be reliably supplied even under the operating conditions where the height difference pressure of the turbo chiller is low.

It was decided to supply the gas refrigerant for cooling to the spaces S1 and S2 surrounded by the holding

portions

44a and 44b for holding the

magnetic bearing coils

30a and 30b, the

magnetic bearing coils

30a and 30b and the

auxiliary bearings

32a and 32b. By supplying the gas refrigerant to the spaces S1 and S2 surrounded in this way, the gas refrigerant is first supplied to the sides of the

magnetic bearing coils

30a and 30b, and then the gas refrigerant is supplied to the

magnetic bearing coils

30a and 30b and the rotating shaft. It can be flowed between 24 and 24. As a result, the gas refrigerant can be reliably supplied around the

magnetic bearing coils

30a and 30b, and the cooling efficiency can be improved.

The casing 12 of the turbo compressor 3 is cooled by the cooling jacket 15 to which the cooling medium is supplied. The heat generated by the

magnetic bearing coils

30a and 30b is thermally conducted to the casing 12 and cooled by the cooling jacket 15. By using the casing 12 as a heat sink in this way, the cooling capacity of the

magnetic bearing coils

30a and 30b can be increased.

<Modification example>
The present embodiment can be modified as follows.
As shown in FIG. 3, instead of the configuration shown in FIG. 1, a two-stage expansion refrigerant circuit having an intercooler 40 may be used. A first expansion valve 7a is provided between the intercooler 40 and the condenser 5, and a second expansion valve 7b is provided between the intercooler 40 and the evaporator 9. An intermediate pressure gas refrigerant pipe 42 that connects the intercooler 40 and the suction side of the second stage impeller 13b is provided. In this modification, the liquid refrigerant supply pipe 14'and the gas refrigerant supply pipe 16' are guided from the intercooler 40 to the casing 12.

<Second Embodiment>
A second embodiment of the present invention will be described. In this embodiment, the paths of the gas refrigerant for cooling the

magnetic bearing coils

30a and 30b described in the first embodiment are different. Therefore, in the following description, the parts different from the first embodiment will be mainly described, and the other parts are the same as those of the first embodiment.

As shown in FIG. 4, the gas refrigerant supply pipe 16 (see FIG. 1) branches into a first gas refrigerant supply pipe 16a and a second gas refrigerant supply pipe 16b. The first gas refrigerant supply pipe 16a is connected to the first gas refrigerant supply hole 46a formed in the first holding portion 44a. The outlet of the first gas refrigerant supply hole 46a is open to the first space S1. The second gas refrigerant supply pipe 16b is connected to the second gas refrigerant supply hole 46b formed in the second holding portion 44b. The outlet of the second gas refrigerant supply hole 46b is open to the second space S2.

According to the present embodiment, the gas

refrigerant supply holes

46a and 46b need only be formed in the holding

portions

44a and 44b without forming holes in the rotary shaft 24 as in the first embodiment, so that the processing is easy. Is.

In each of the above-described embodiments, a liquid refrigerant is used as the cooling medium supplied to the cooling jacket 15, but the present invention is not limited to this, and for example, cooling water supplied from the outside of the turbo compressor 3 is used. You may.

1 Turbo chiller 3 Turbo compressor 5 Condenser 7 Expansion valve 7a 1st expansion valve 7b 2nd expansion valve 9 Evaporator 10 Electric motor 12

Casing

13a, 13b Impeller 14, 14'Liquid refrigerant supply pipe 15 Cooling jacket (casing) Cooling part)
16, 16'Gas refrigerant supply pipe (gas refrigerant supply path)
16a 1st gas refrigerant supply pipe 16b 2nd gas refrigerant supply pipe 17a Axial direction gas refrigerant supply hole 17b1 1st radial gas refrigerant supply hole 17b2 1st radial gas refrigerant supply hole 18a 1st refrigerant return pipe )
18b Second refrigerant return pipe 20 Rotor 22 Stator 24 Rotating shaft (rotating shaft)
24a Disc 26 Cooling heat transfer tube 28 Cold water heat transfer tube 30 Magnetic bearing 30a 1st radial magnetic bearing coil 30b 2nd radial magnetic bearing coil 30c Thrust magnetic bearing coil 32a 1st auxiliary bearing (auxiliary bearing)
32b 2nd auxiliary bearing (auxiliary bearing)
40 Intercooler 42 Intermediate pressure gas refrigerant piping 44a 1st holding part 44b 2nd holding part G1 1st gap sensor G2 2nd gap sensor S1 1st space S2 2nd space

Claims

A turbo compressor that compresses the refrigerant, a condenser that condenses the refrigerant discharged from the turbo compressor, an expansion valve that expands the liquid refrigerant derived from the condenser, and a refrigerant derived from the expansion valve. With a refrigeration cycle, with an evaporator to evaporate,
The turbo compressor
With an impeller
A rotating shaft that rotates the impeller,
A magnetic bearing that supports the rotating shaft and
A gas refrigerant supply path that supplies a gas refrigerant as a cooling medium to the magnetic bearing from a high-pressure portion on the upstream side of the refrigeration cycle with respect to the expansion valve.
A gas refrigerant return path that guides the gas refrigerant that has passed through the magnetic bearing to a low-pressure portion downstream of the expansion valve on the downstream side of the refrigeration cycle.
A turbo chiller equipped with.
The turbo chiller according to claim 1, wherein the gas refrigerant supplied from the gas refrigerant supply path passes between the magnetic bearing and the rotating shaft.
The gas refrigerant supply path is connected to the axial gas refrigerant supply hole formed in the axial direction of the rotary shaft and the axial gas refrigerant supply hole, and is formed radially outward toward the magnetic bearing side. The turbo chiller according to claim 1 or 2, further comprising a radial gas refrigerant supply hole.
A holding portion that holds the magnetic bearing and
Auxiliary bearings fixed to the holding portion and provided on the side of the magnetic bearing,
The turbo chiller according to any one of claims 1 to 3, wherein the gas refrigerant is supplied from the gas refrigerant supply path to the space surrounded by the holding portion, the magnetic bearing, and the auxiliary bearing.
The turbo chiller according to any one of claims 1 to 4, further comprising a casing cooling unit in which a cooling medium is supplied to a casing accommodating the turbo compressor.