JP3425351B2 - Two-stage centrifugal compressor - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a two-stage centrifugal compressor directly driven by a high frequency electric motor.

[0002]

2. Description of the Related Art High-temperature discharge gas compressed by a compressor is
Exchanging heat with the cooling medium liquid circulating in the closed circulation circuit is disclosed in, for example, Japanese Patent Laid-Open No. 4-350392.
-72598. By circulating the cooling medium in the closed circuit, it is possible to install the compressor unit device, downsize the unit device, convenience in areas where cooling water is not available, and use in areas with poor water quality. It is described in these publications.

[0003]

In each of the above publications, the compressor is a rotary oilless compressor, that is, a positive displacement compressor, and a turbo compressor such as a centrifugal compressor is used. It's different from the machine. The turbo type compressor has a relatively large capacity, and its calorific value is several times or more that of the positive displacement compressor. If an air-cooled heat exchanger is used to radiate this large amount of heat, there is a problem that the heat exchanger has a huge volume.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to realize long-term maintenance-free operation in a centrifugal compressor directly driven by a high frequency electric motor. Another object of the present invention is to provide an environment in which cooling water freezes at low outside temperatures in winter,
Another object is to realize a centrifugal compressor that can cool the discharge gas compressed by the compressor even in an environment where the cooling water cannot be supplied. Still another object of the present invention is to improve the cooling efficiency by improving the flow path of the cooling air for cooling the centrifugal compressor.

[0005]

A first feature of the present invention for achieving the above object is to provide a rotor shaft capable of high speed rotation,
An electric motor rotor portion formed at an intermediate portion of the rotor shaft, first and second impellers attached to both end portions of the rotor shaft, and a first impeller and an electric motor rotor rotatably supporting the rotor shaft. The first and second radial magnetic bearings disposed between the rotor portion of the motor and the second portion and the second impeller, and the thrust magnetic bearing disposed between the first radial bearing and the rotor portion of the motor; In a two-stage compressor provided with a second magnetic bearing, a thrust bearing, and an electric motor casing accommodating a rotor, a cooling jacket for cooling the electric motor is formed in the electric motor casing, and compressed by the first impeller. A first cooler for cooling the gas and a second cooler for cooling the gas compressed by the second impeller are provided, and the jacket portion, the first cooler and the second cooler are circulated. A radiator that cools the refrigerant It includes those were.

A second feature of the present invention for achieving the above object is to provide a rotor shaft capable of high-speed rotation, an electric motor rotor portion formed in an intermediate portion of the rotor shaft, and both end portions of the rotor shaft. The first and second impellers, and the first and second rotors that rotatably support the rotor shaft and are disposed between the first impeller and the motor rotor part and between the second impeller and the rotor part of the motor.
Radial magnetic bearings, a first radial bearing and a thrust magnetic bearing arranged between the rotor portion of the electric motor, and the first and second
In a two-stage compressor including a magnetic bearing, a thrust bearing, and an electric motor casing that houses the rotor, a cooling jacket portion for cooling the electric motor is formed in the electric motor casing and compressed by the first impeller. A first cooler for cooling the gas and a second cooler for cooling the gas compressed by the second impeller are provided to cool the refrigerant flowing through the jacket portion and the second cooler. It is equipped with a radiator.

Preferably, a blower means is provided near the radiator for taking in external air into the compressor for exchanging heat with the refrigerant flowing in the radiator, and means for guiding the external air taken in by the blower means to the electric motor rotor section. A closed circuit for circulating the refrigerant through the jacket, the first cooler and the radiator; a closed circuit for circulating the refrigerant through the jacket, the first cooler, the radiator and the second cooler It is equipped with.

Further preferably, a second cooler for cooling the gas pressurized by the second impeller and a blowing means for blowing air to the radiator are provided in the vicinity of the radiator, and the second cooler has an internal structure. This is a liquid-gas heat exchanger in which the circulating gas exchanges heat with the external air taken in by the blowing means.

Further, a pump means for increasing the pressure of the refrigerant is provided in the closed circuit, and the pump means and the blower means are driven by the same drive means; cooling containing a first cooler and a second cooler. A casing is provided in the lower portion of the electric motor casing; the electric motor casing and the cooling casing are integrally cast; partition means for separately accommodating the first cooler and the second cooler is provided in the cooling casing; You may make it arrange | position a radiator and a ventilation means in the accommodation compartment of the 2nd cooler of the cooling casing formed by this.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a longitudinal sectional view and a side view of an embodiment of a centrifugal compressor that directly drives a compressor impeller with an electric motor according to the present invention. The centrifugal compressor is a package type two-stage compressor. The rotor part of the high-frequency motor 1 is formed in the center of the rotor 2.
Impellers 6 and 7 are attached to both ends of the shaft. Radial magnetic bearings 3, 4 are provided between the electric motor 1 and the impellers 6, 7.
However, a thrust magnetic bearing 5 is arranged between the electric motor 1 and the radial magnetic bearing 3, and the rotor 2 is supported by these magnetic bearings in a non-contact manner. The electric motor 1, the rotor 2, and the bearings 3, 4, and 5 are housed in an electric motor casing 8 formed in a cylindrical shape or in two split shapes.

On the other hand, the low-pressure compression stage having the impeller 6 is housed in the compressor casing 13, and the high-pressure compression stage having the impeller 7 is housed in the compressor casing 14. The compressor casings 13 and 14 are integrally connected to an electric motor casing 8 that houses the electric motor 1 and also to a cooler casing 15 described later. The above is the case where the compressor casings 13 and 14 are configured in a cylindrical shape, but only the upper half of the compressor casings 13 and 14 is a separate body, and the lower half is a structure integrated with the cooler casing 15, for example, It can also be a cast product. In this case, the number of parts can be reduced. Further, the electric motor casing 8 can also be a cast product integrated with the cooler casing. By doing so, the number of parts can be further reduced. Although not shown, the electric motor casing 8, the compression stage casing 13,
It is also possible to make 14 a cylindrical shape and to form a casting structure in which the cooler casing 15 is also integrated, and to cover this integrated casting from both the left and right sides. In this case, the half-split structure of the casing is unnecessary, and the assembling accuracy is improved.

The high frequency motor 1 has a jacket portion 1 for removing heat generated from copper wires and laminated steel plates (not shown).
6, the jacket 16 is provided with an inlet 16a for introducing the cooling refrigerant liquid and an outlet 16b. The coolant liquid that has cooled the jacket portion 16 and heated up is cooled by exchanging heat with the outside air by a radiator 18 described later, and cools the jacket portion 16 again. As the coolant liquid, a coolant liquid containing propylene glycol may be used in an environment in which the heat exchanger may be contaminated or corroded. Also,
This refrigerant also has the advantage that it can withstand use in cold regions.

Further, cooling air is introduced into the electric motor 1 from the outside in order to dissipate heat generated due to wind loss and eddy current loss of the rotor 2. The introduction hole 17a for introducing the cooling air is provided in the substantially central portion of the electric motor 1,
The cooling air after cooling is discharged from the discharge pipe 17b (see FIG. 3) connected to the electric motor 1.

FIG. 2 is a view taken along the line AA of FIG. 1 and shows a state in which the compressor casing 14 and the cooler are integrally structured. In FIG. 2, the cooler is a compressor casing 14
Casings for two coolers arranged below each other, an intercooler casing 15a and a discharge cooler casing 15b
And a cooling casing 15 is constituted by both of these casings. Both casings 15a, 15b
Inside, a plurality of cooling-refrigerant liquid pipes 11a flowing in the intercooler casing 15a and a plurality of cooling-refrigerant liquid pipes 12a flowing in the discharge cooler 15b are respectively arranged substantially parallel to the axis of the rotor 2. ing. In FIG. 2, the thick arrow 1 indicates the flow of gas supplied from the discharge cooler 12 to the demand side.
Shown by 9. The cooling casing may have a configuration in which one container is partitioned.

FIG. 3 is a system flow diagram of the centrifugal compressor described in the above embodiment. The compressor device includes an electric motor jacket 16, an intercooler 11, a discharge cooler 12, and a closed circulation path for cooling refrigerant liquid. Is equipped with. The refrigerant liquid flowing in the closed circulation circuit exchanges heat with the discharge gas discharged from the low pressure compression stage in the intercooler 11 to reach a high temperature, and then flows into the radiator 18. The refrigerant liquid exchanges heat with the outside air in the radiator 18 to become a low-temperature refrigerant, and the liquid circulation pump 2
The pressure is increased at 2 and is returned to the intercooler 11. There is also provided a pipe branching from the middle of the closed circulation path to guide the refrigerant liquid to the discharge cooler 12 and the compressor body casing. That is, a part of the refrigerant liquid branches and flows from between the intercooler 11 and the liquid circulation pump 22, exchanges heat with the discharge gas in the discharge cooler 12, and between the intercooler 11 and the radiator 18. Will be returned. A connection pipe 23 connects the devices provided in the closed circuit. The connecting pipe 23a is a connecting pipe for the intercooler, the connecting pipe 23c is a connecting pipe for the discharge cooler, and the connecting pipe 23b is a connecting pipe for the motor casing.

In the package type centrifugal compressor, the radiator 18 is arranged in the vicinity of the wall surface to facilitate the intake of external air. Inside the radiator 18 inside the compressor, a fan 20 is arranged so as to accelerate cooling of the radiator 18. It should be noted that the position of the fan is not limited to this position, and may be any position as long as it makes it easy to take in external air into the radiator. The fan 20 has a fan main body 20a having rotating blades, and a fan casing 20b surrounding the fan main body 20a. The fan casing 20b has a communication air pipe 2 for using a part of the external air blown by the fan body 20a for cooling the electric motor.
1 is connected. Electric motor 19 for driving fan 20
Is also connected to the liquid pump 22 and has a compact structure capable of simultaneously transporting the refrigerant and the cooling air.

FIG. 4 shows a system flow chart of another embodiment of the present invention. This embodiment is different from the first embodiment in that
The discharge gas of the high-pressure compressor stage is cooled by the air-cooled discharge cooler 12. For this reason, radiator 1
8 and the discharge cooler 12 are arranged side by side, and the cooling fan 20 takes in external air from both of them. In addition,
The arrangement of the radiator 18 and the discharge cooler 12 is not limited to this arrangement, and any arrangement may be used as long as both can be cooled by air. Further, in this case, the aftercooler casing 15b shown in FIG.
If the discharge cooler 12 and the cooling fan 20 are housed, the compactness of the compressor device is not impaired,
In addition, the device arrangement is stable. Further, in this embodiment, since the flow rate of the coolant liquid for cooling can be reduced,
There are energy saving effects such as the power of the liquid pump can be reduced and the power of the cooling fan can be reduced. There is also an effect that the radiator can be downsized.

In both of the above embodiments, it is desirable to cool the electromagnetic bearing as well. In this case, if the cooling passage for cooling the bearings 3, 4, 5 is branched from the connection pipe 21 connected to the cooling fan casing 21b, the space is saved and the configuration is simplified. Further, since the air temperature after cooling the electric motor 1 reaches 120 ° C., it is not preferable to directly discharge this air to the outside of the compressor. Therefore, in this embodiment, the air that has cooled the electric motor 1 is returned to the compression stage casing 13 provided on the suction side of the compressor (not shown). This can prevent hot air from being blown out of the compressor and adversely affecting people around the apparatus.

As described above, according to the embodiments of the present invention, the turbo compressor is driven by the high frequency electric motor and supported by the magnetic bearings, so that the compressor can be a completely oilless compressor. .

Even in the case of an oilless compressor, if cooling water is used for the heat exchanger, regular maintenance is indispensable due to clogging due to contamination of the cooling water and corrosion caused by impurities in the cooling water. is there. Further, if the heat exchanger is integrated with the compressor body for compactness, maintenance of the heat exchanger becomes complicated, which is not easy. Furthermore, when using a turbo compressor in cold regions,
The heat exchanger using cooling water has a risk of freezing. Furthermore, in compressors or portable compressors used in underground or desert areas where the supply of cooling water is impossible or limited, a heat exchange means to replace cooling water is required.

These inconveniences can be eliminated by the respective embodiments of the present invention. That is, in the present invention, since the cooling water can be completely omitted from the turbo compressor, the turbo compressor can be easily used even in an environment where the conditions of the cooling water are bad.
Furthermore, since the fan that blows air to the heat exchanger of the turbo compressor blows air to the electric motor as well, the cooling system is simplified, and the size of the device is reduced and the cooling efficiency is improved.

When a high frequency electric motor is used to drive the compressor, the rotor of the electric motor rotates at a high speed, and wind loss and eddy current loss occur in the rotor section. Further, the same loss occurs in the magnetic bearing portion that supports the rotor. In order to effectively dissipate the heat generated due to this loss, it is necessary to circulate the cooling air in the gap between the rotating portion (rotor) and the stationary portion (stator). As the cooling air, external air sucked by a cooling fan provided near a radiator that cools the cooling medium liquid was used. This saves energy as a compressor device.

In any of the above-mentioned embodiments, the capacity of the compressor is 55 to 500 kW, and the rated rotation speed is 120,000 RPM for the 55 kW machine and 40,000 RPM for the 500 kW machine, achieving high speed miniaturization of the compressor. ing. This makes it possible to use an air-cooled heat exchanger.

[0024]

According to the present invention, since the turbo compressor is a completely oilless compressor supported by a magnetic bearing using a high frequency electric motor as a drive, maintenance-free can be realized.

Further, according to the present invention, since the wind generated by the fan for blowing the heat exchanger is also blown to the electric motor section, a small and compact turbo compressor can be provided.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of a compressor body according to the present invention.

FIG. 2 is a side view of the compressor body shown in FIG.

FIG. 3 is a system flow diagram of an embodiment of the present invention.

FIG. 4 is a system flow chart of another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... High frequency motor part, 2 ... Rotor, 3, 4 ... Radial magnetic bearing, 5 ... Thrust magnetic bearing, 6, 7 ... Impeller, 8 ...
Motor casing, 11a ... Pipe for cooling refrigerant liquid, 12 ... Discharge cooler, 12a ... Discharge cooler cooling refrigerant liquid pipe, 13, 1
4 ... Compressor casing, 15 ... Cooler casing, 15
a ... intercooler casing, 15b ... discharge cooler casing, 16 ... jacket part, 16a ... cooling refrigerant liquid intake port, 16b ... discharge port, 17a ... cooling air introduction hole, 17
b ... Discharge pipe, 18 ... Radiator, 19 ... Driving machine, 20 ...
Fan, 20a ... Fan body, 20b ... Fan casing, 21 ... Communication air piping, 22 ... Cooling refrigerant liquid circulation pump, 23 ... Connection piping, 23a ... Intercooler communication piping,
23b ... Motor casing jacket communication pipe, 23c
… Communication piping for discharge cooler.

Front page continuation (72) Inventor Naohiko Takahashi 603 Kazutachi-cho, Tsuchiura-shi, Ibaraki Hitachi Co., Ltd. Tsuchiura factory (72) Inventor Kazuki Takahashi 603 Jin-cho, Tsuchiura-shi, Ibaraki Hitachi Ltd. Tsuchiura factory (56 ) Reference JP-A-5-149287 (JP, A) JP-A-56-6091 (JP, A) JP-A-2-156556 (JP, A) Actually open 3-19499 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F04D 1/06-1/08 F04D 13/06 F04D 17/12-17/14 F04D 29/04 F04D 29/58 F04B 39/00

Claims (11)

(57) [Claims] 1. A rotor shaft capable of high-speed rotation, an electric motor rotor portion formed at an intermediate portion of the rotor shaft, first and second impellers attached to both ends of the rotor shaft, and the rotor shaft. Rotatably supporting the first impeller and the motor rotor section, and the first and second radial magnetic bearings arranged between the second impeller and the rotor section of the electric motor; and the first radial bearing. A two-stage compressor including a thrust magnetic bearing arranged between rotor portions of the electric motor, and an electric motor casing accommodating the first and second magnetic bearings, the thrust bearing and the rotor, wherein: A first cooler that forms a cooling jacket for cooling the electric motor, cools the gas compressed by the first impeller, and a second cooler that cools the gas compressed by the second impeller. With a cooler, A two-stage centrifugal compressor comprising: a jacket, a radiator that cools a refrigerant that flows through the first cooler, and the second cooler. 2. A rotor shaft capable of high-speed rotation, an electric motor rotor portion formed at an intermediate portion of the rotor shaft, first and second impellers attached to both ends of the rotor shaft, and the rotor shaft. Rotatably supporting the first impeller and the motor rotor section, and the first and second radial magnetic bearings arranged between the second impeller and the rotor section of the electric motor; and the first radial bearing. A two-stage compressor including a thrust magnetic bearing arranged between rotor portions of the electric motor, and an electric motor casing accommodating the first and second magnetic bearings, the thrust bearing and the rotor, wherein: A first cooler that forms a cooling jacket portion for cooling the electric motor, cools the gas compressed by the first impeller, and a second cooler that cools the gas compressed by the second impeller. With a cooler A two-stage centrifugal compressor, comprising: a radiator that cools a refrigerant that flows through the jacket portion and the second cooler. 3. A means for taking in external air, which exchanges heat with a refrigerant flowing through the radiator, into a compressor in the vicinity of the radiator, and means for introducing the external air taken in by the air blowing means to the electric motor rotor section. The two-stage centrifugal compressor according to claim 1 or 2, further comprising: 4. The two-stage according to claim 1, further comprising a closed circulation path through which a refrigerant circulates through the jacket portion, the first cooler, and the radiator. Centrifugal compressor. 5. The two-stage according to claim 1, further comprising a closed circulation path through which a refrigerant circulates through the jacket portion, the first cooler, the radiator, and the second cooler. Centrifugal compressor. 6. A second cooler for cooling the gas boosted by the second impeller and a blowing means for blowing air to the radiator are provided in the vicinity of the radiator, and the second cooler has an internal structure. The two-stage centrifugal compressor according to claim 2, characterized in that the gas flowing through is a liquid-gas heat exchanger that exchanges heat with the external air taken in by the blowing means. 7. A two-stage centrifugal compressor according to claim 3, wherein pump means for increasing the pressure of the refrigerant is provided in the closed circuit, and the pump means and the blower means are driven by the same drive means. . 8. The two-stage centrifugal compressor according to claim 1, wherein a cooling casing for accommodating the first cooler and the second cooler is provided in a lower portion of the electric motor casing. . 9. The two-stage centrifugal compressor according to claim 8, wherein the electric motor casing and the cooling casing are integrally cast. 10. The two-stage centrifugal compression according to claim 9, wherein the cooling casing is provided with partition means for separately storing the first cooler and the second cooler. Machine. 11. The two-stage centrifuge according to claim 10, wherein the radiator and the blower are arranged in a storage compartment of the second cooler of the cooling casing formed by the partition means. Compressor.