JPH11351198A - Turbo compressor system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo compressor system capable of reducing a maintenance cost while restricting noise due to blow-off during non-load operation. SOLUTION: A turbo compressor system includes turbo compressors 1a, 1b connected to a suction pipe 8 provided with a filter 35 in a suction port, a discharge pipe 10 connected to the discharge side of the final stage compressor 1b, a blow-off passage 11 having one end connected to the discharge pipe 10 and the other end connected to the suction side of the first stage compressor 1a and a blow-off valve 4 provided in the blow-off passage 11, wherein the blow-off valve 4 is open during non-load operation to guide compressed air discharged from the final stage compressor 1b via the discharge pipe 10 to the suction side of the first stage compressor 1a. A chamber 14 and a hole 15 are provided at a joint 12 between the other end of the blow-off passage 11 and the suction side of the first stage compressor 1a for using air guided via the blow-off passage 11 during non-load operation to increase the peripheral velocity component of an air flow on the suction side of the first stage compressor 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo compressor system having at least one stage of turbo compressor.

[0002]

2. Description of the Related Art For example, a turbo compressor is often used to supply compressed air at a predetermined pressure to a consuming system such as a pneumatic device. At this time, the consumption system may require a large amount of compressed air, but may not require much. In order to cope with this, there is a method of adjusting the flow rate of the compressor by increasing or decreasing the flow rate. However, due to the characteristics of the compressor, if the flow rate is reduced too much, a so-called surge occurs, and pulsation occurs to make the operation impossible. Therefore, in order to avoid this, if the compressed air is not required in the consuming system, it is conceivable to stop the supply to the consuming system. However, the compressor is stopped and restarted every time a frequent consumption fluctuation occurs. This is not preferable from the viewpoint of the fatigue of the members and the like, so that the compressor is normally operated under no load.

[0003] For example, in an air turbo compressor system having two or more stages of turbo compressors and an air cooler and capable of switching between the no-load operation and the load operation,
Usually, a blow-off valve is provided downstream of the last-stage air cooler, and a throttle valve is provided in the first-stage suction pipe. Then, during the no-load operation, the blow-off valve is opened to blow air to the atmosphere, and the first-stage suction throttle valve is closed. Since the suction pressure is reduced by closing the suction throttle valve, the driving power of the first-stage compressor can be significantly reduced. However, in such a conventional technique, there is a problem that the noise is large because the air is blown to the atmosphere during the no-load operation. In addition, since the load operation and the no-load operation are repeated at a considerably high frequency in accordance with frequent fluctuations in consumption, the number of switching operations of the suction throttle valve and the blow-off valve increases, and these two valves fail. Easier to do. Therefore, both of them need to be replaced and repaired in a relatively short period of time, and there is a problem that maintenance cost of the compressor is increased.

On the other hand, among the turbo compressors for air that switch between load operation and no-load operation, those that take into account the above-mentioned noise reduction, for example, as described in Japanese Patent Application Laid-Open No. H8-121398, use a first stage suction pipe. While a suction throttle valve (suction valve) is provided, a discharge line provided with a discharge valve in the middle is connected to a discharge line downstream of the last-stage air cooler, and this discharge line is connected upstream of the suction throttle valve of the suction pipe. Those connected to the side parts have been proposed. In the above structure, during normal load operation, the suction throttle valve (suction valve) provided on the suction pipe is opened, and the blow-off valve is closed. On the other hand, during the no-load operation, the suction throttle valve (suction valve) closes and the blow-off valve opens. The air is led to the suction pipe through the blow-off line and is blown off. At this time, since a filter is provided in the suction pipe and the sound at the time of air blowing can be cut off, noise can be reduced.

[0005]

However, in the turbo compressor described in Japanese Patent Application Laid-Open No. 8-121398,
As in the above-described prior art, there still remains a problem that the number of switching operations of the suction throttle valve and the blow-off valve is large and maintenance cost of the compressor is high.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to suppress the noise caused by blowing air during no-load operation and reduce the maintenance cost. Is to provide.

[0007]

(1) In order to achieve the above object, the present invention relates to a suction pipe having a filter at a suction port, and at least one stage turbo compressor connected to the suction pipe. A discharge pipe connected to the discharge side of the last stage compressor,
The load operation includes a blow-off passage having one end connected to the discharge pipe and the other end connected to the suction side of the first-stage compressor, and a blow-off valve provided in the blow-off passage to open and close the blow-off passage. Sometimes, while the blow-off valve is closed, during no-load operation, the blow-off valve is opened to allow the compressed air discharged from the last-stage compressor through a discharge pipe to the suction side of the first-stage compressor through the blow-off passage. In the turbo-compressor system leading to the first stage compressor, the air at the other end of the discharge passage is connected to the suction side of the first stage compressor using air guided through the discharge passage during the no-load operation. A circumferential speed increasing means is provided for increasing a circumferential speed component of the air flow on the suction side. During a no-load operation for reducing the compressor driving power, the blow-off valve is opened, and the compressed air discharged from the last-stage compressor through the discharge pipe is guided to the first-stage compressor suction side through the discharge passage. At this time, there is a possibility that the sound of the air flow introduced from the air discharge passage may propagate to the suction port side of the suction pipe, but the sound is generated by the filter provided at the suction port of the suction pipe. Radiation to the outside can be blocked, thereby suppressing noise due to wind blowing. Further, at this time, the circumferential speed component of the airflow on the suction side of the first stage compressor is increased by the circumferential speed increasing means provided at the connection with the suction side of the first stage compressor. Here, in general, the theoretical head of the impeller provided in the compressor is as follows: ｛(peripheral speed of the impeller at the exit) × (peripheral speed of the flow at the exit of the impeller) − (peripheral speed of the impeller at the entrance) × (impeller) The circumferential velocity of the inlet flow)｝ / gravity acceleration. In the present invention, by increasing the circumferential velocity component of the suction-side flow, the circumferential velocity of the impeller inlet flow in the above equation for the first stage compressor can be increased. As a result, the theoretical head of the impeller of the first stage compressor can be reduced, so that the driving power of the first stage compressor can be reduced. As described above, since no-load operation is performed by operating only the blow-off valve and the compressor drive power can be reduced, the suction throttle valve can be omitted. Therefore, compared with the conventional structure in which it is necessary to operate both the blow-off valve and the suction throttle valve, the number of valves as a movable part that needs to be replaced or repaired can be reduced by one. Can be reduced.

(2) In the above (1), preferably,
The circumferential speed increasing means is provided in a chamber communicating with the air discharge passage and surrounding a part of the suction pipe, and is provided in the chamber inner tube wall portion of the suction pipe, and is introduced into the chamber from the air discharge passage. At least one first air guide hole for supplying the supplied air into the suction pipe, and the first air guide hole is provided in the suction pipe circumferential component of the air supplied into the suction pipe. Is arranged in such a direction as to be in the direction along the rotation direction of the impeller of the turbo compressor.

(3) In the above (1), preferably, the circumferential speed increasing means is provided in a suction casing of the first stage compressor, and transfers air from the discharge passage to a suction flow in the suction casing. At least one second air guide hole for supplying to a road, and the second air guide hole is provided with:
The turbo is characterized by being arranged such that a circumferential component of the air supplied to the suction passage in the suction passage is in a direction along a rotation direction of an impeller of the turbo compressor. Compressor system.

(4) In the above (2) or (3), more preferably, the first or second air guide hole has an axial component of air supplied into the suction pipe or the suction channel. It is arranged in such a direction as to be substantially opposite to the air flow in the suction pipe or the suction passage. Thereby, when air is supplied from the first or second air guide hole into the suction pipe or the suction flow path, the air collides with the air in the suction pipe or the suction flow path to generate a collision loss (pressure loss). Therefore, the pressure at the inlet of the first stage compressor on the downstream side decreases. Thereby, the driving power of the first-stage compressor can be further reduced. (5) In the above (1), preferably, an electric motor for driving the at least one-stage turbo compressor, and a portion of the air in the air discharge passage branched from the air discharge passage and separated from the air discharge passage are provided. A cooling pipe for leading to a cooling passage of the motor.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a system diagram of a turbo compressor system according to the present embodiment. In FIG. 1, the turbo compressor system according to the present embodiment includes a suction pipe 8 having a suction filter 35 at a front end suction port, a turbo compressor 1 connected to the suction pipe 8, and a discharge of the compressor 1. It has a discharge pipe 10 connected to the side, an air discharge passage 11, and an air discharge valve 4 provided in the air discharge passage 11 to open and close the air discharge passage 11.

The turbo compressor 1 comprises a first stage compressor 1a,
And a stage (last stage, the same applies hereinafter) compressor 1b, and both are driven by the prime mover 2. The first stage compressor 1a and the second stage compressor 1b are connected by a pipe 9 provided with an intermediate air cooler 3a in the middle.

[0014] The suction pipe 8 is connected to the upstream side of the first stage compressor 1a. Further, the discharge pipe 10 is connected to the discharge side of the second-stage compressor 1b, and the second-stage air cooler 3
b, a check valve 5 and a pressure switch 6. Note that a receiver tank 7 is branched and connected further downstream of the discharge pipe 10, and further downstream is connected to a demand side system.

One end (upstream end) of the air discharge passage 11 is connected to a joint 13 located between the air cooler 3 b and the check valve 5 in the discharge pipe 10. In addition, ventilation passage 1
The other end (downstream end) of 1 is connected at a joint 12 of a suction pipe 8 on the suction side of the first stage compressor 1a. The opening and closing of the blow-off valve 4 provided in the blow-off passage 11 is controlled based on the pressure measured by the pressure switch 6.

FIG. 2 is a longitudinal sectional view showing the details of a joint 12 between the air discharge passage 11 and the suction pipe 8 in FIG. 1, which is a main part of the present embodiment. Fig. 3 shows a cross section.
Shown in 2 and 3, the outer periphery of the suction pipe 8 is provided with a ventilation passage 11 so as to surround a part of the suction pipe 8.
Is provided with a bottomed cylindrical chamber 14 for introducing the air blown out. A plurality of holes 15 for guiding the air in the chamber 14 to the inside of the suction pipe 8 are formed in the pipe wall portion 8 a of the suction pipe 8 located in the chamber 14. The hole 15 is arranged so as to be inclined such that a component XP (see FIG. 2) of the flow X blown out from the hole 15 in the suction pipe axial direction is substantially opposite to the original suction air flow 16 in the suction pipe 8. In addition, the component XQ in the suction pipe circumferential direction (see FIG. 3) of the flow X blown out from the hole 15 is arranged so as to be inclined in the direction along the impeller rotation direction 17. The cross-sectional shape of the plurality of holes 15 is not particularly limited, such as a round hole, an elliptical hole, a long hole, and a flat hole.

Next, the operation and operation of the turbo compressor system having the above configuration will be described.

(1) At the time of load operation At the time of normal load operation, the air sucked from the suction pipe 8 through the suction filter 35 is pressurized by the first stage compressor 1a, and then cooled by the intermediate air cooler 3a. It is sucked into the second stage compressor 1b. The air further pressurized by the second-stage compressor 1b is cooled by the second-stage (final-stage) air cooler 3b, and then enters the receiver tank 7 through the check valve 5, and enters the demand-side process. Sent.

(2) At the time of no-load operation Here, when the pressure of the receiver tank 7 is within a predetermined range, a normal load operation is performed. However, the use of air in the demand side process is reduced and the receiver tank 7
If the pressure exceeds the upper limit, the compressor will surge when the load operation is continued. To avoid this, the operation is switched from the load operation to the no-load operation. That is, the blow-off valve 4 is opened by the control signal of the pressure switch 6, and the air is guided from the blow-off passage 11 to the chamber 14 of the joint 12,
Further, the suction pipe 8 is introduced into the suction pipe 8 through a plurality of holes 15 provided in the suction pipe pipe wall portion 8 a located in the chamber 14.

At this time, there is a possibility that the sound of the flow X introduced from the air discharge passage 11 propagates to the suction port side of the suction pipe 8, but a filter 35 is provided at the suction port of the suction pipe 8. By this, the sound can be blocked from being radiated to the outside, so that the noise due to the blowing can be suppressed. That is, noise can be reduced as compared with a structure in which the discharged air is directly discharged to the atmosphere.

At this time, the flow X blown out from the hole 15
Is that the component XQ in the circumferential direction of the suction pipe 8 is the impeller rotation direction 1
7 (see FIG. 3), the air flow 16 flowing from the suction pipe 8 to the first stage compressor 1a is swirled to increase its circumferential velocity component. Here, in general, the theoretical head of the impeller provided in the compressor (the work applied to a unit weight of fluid) Hth is Hth = (u ₂ cu ₂ −u ₁ cu ₁ ) / g where u ₂ : Impeller peripheral speed u ₁ : Inlet impeller peripheral speed cu ₂ : Impeller exit flow circumferential direction (impeller rotation direction) speed cu ₁ : Impeller inlet flow circumferential direction (impeller rotation direction) speed g: Gravity It is expressed by acceleration of. In the present embodiment, the hole 15 increases the circumferential velocity component of the air flow 16 flowing from the suction pipe 8. That is, the chamber 14 and the hole 15 function as a circumferential speed increasing means for increasing the circumferential speed component of the air flow on the suction side of the first stage compressor using the air guided through the air discharge passage during the no-load operation. The circumferential speed cu ₁ of the impeller inlet flow in the above equation can be increased for the first stage compressor 1a. As a result, the impeller theoretical head Hth of the first-stage compressor 1a can be reduced accordingly, so that the driving power of the first-stage compressor 1a can be reduced. Therefore, the power consumption of the turbo compressor system during the no-load operation can be significantly reduced as compared with the load operation during the load operation.

In the flow X blown out from the hole 15, the component XP in the axial direction of the suction pipe 8 is substantially opposite to the flow 16 of the original suction air in the suction pipe 8 (see FIG. 2). (Pressure loss) occurs, and the pressure downstream of the joint 12, that is, the pressure at the inlet of the first stage compressor 1 a decreases. Therefore,
Thus, the driving power of the first stage compressor 1a can be reduced.

As described above, according to the present embodiment, the no-load operation is performed by operating only the blow-off valve 4 and the driving power of the compressor 1a can be reduced (Japanese Patent Laid-Open No. 8-12139).
No. 8 can be reduced to the same extent as in Japanese Patent Publication No. 8), so that the suction throttle valve which is essential in the conventional structure can be omitted. Therefore, as compared with the conventional structure in which both the blow-off valve and the suction throttle valve need to be operated, one valve as a movable part which needs to be replaced or repaired can be reduced, so that the reliability is improved and In addition, the maintenance cost of the compressor can be reduced.

In the first embodiment, the component XP of the flow X blown out of the holes 15 in the axial direction of the suction pipe is substantially opposite to the flow 16 of the original suction air in the suction pipe 8. In the section shown in FIG. 2, the suction air flow 16 is inclined in the direction opposite to the direction of the suction air flow 16, but is not limited thereto. It is also possible to arrange them at an angle along the direction 16. In this case, the above-mentioned collision loss (pressure loss)
Has almost no effect, but an effect of increasing the circumferential velocity component of the air flow 16 is obtained.
The effect of reducing the driving power of the first stage compressor 1a can be obtained. The number of holes 15 is not necessarily limited to a plurality, and at least one hole is sufficient.

Further, in the first embodiment,
The turbo compressor 1 has a two-stage configuration including the first-stage compressor 1a and the second-stage compressor 1b, but is not limited thereto, and may be a one-stage turbo compressor or a three-stage or more turbo compressor. is there. In these cases, a similar effect is obtained.

A second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the other end of the air discharge passage 11 is connected to the first stage compressor 1a as shown by an imaginary line (two-dot chain line) in FIG.
This is an embodiment in the case of being connected to suction casings 18 and 19 (described later). Portions common to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

FIG. 4 shows the main parts of the present embodiment, the air discharge passage 11 and the suction casings 18, 19 of the first stage compressor 1a.
FIG. 5 is a vertical cross-sectional view showing details of a joint portion with a (described later), FIG.
FIG. 5 is a cross-sectional view taken along the line BB in FIG.

In FIGS. 4 and 5, the first stage compressor 1a is fitted on a rotating shaft 22 and is provided with an impeller fixing nut 2a.
4 includes an impeller 21 fixed at 4, suction casings 18 and 19 having a partition plate 20 (turn prevention plate) provided upstream of the impeller 21, and a diffuser 27 provided downstream of the impeller 21. ing. Suction casing 18, 19
Inside, a suction passage 23 for guiding the air flow 16 introduced from the suction pipe 8 to the impeller 21 is formed. At this time, the blow-off passage 11 is connected to the suction casing 18 and the chamber 2 for introducing the blown-out air.
5 and a plurality of holes 26 connecting the chamber 25 and the suction channel 23 are provided. The hole 26 is provided at a position downstream of the partition plate 20 in the suction flow path 23, and is provided at right angles to the axis of the rotating shaft 22. As a result, the hole 26 causes the component XP (see FIG. 4) of the flow X blown out of the hole 26 in the suction flow channel axial direction to be substantially opposite to the original flow 16 of the suction air in the suction flow channel 23. Suction channel 2
3 is inclined. Further, at this time, the structure is such that a component XQ in the circumferential direction of the suction flow path (see FIG. 5) of the flow X blown out from the hole 26 is in a direction along the impeller rotation direction 17.

Other structures are almost the same as those of the first embodiment.

In the above configuration, at the time of no-load operation, air is guided from the air discharge passage 11 to the chamber 25, and further from the plurality of holes 26 of the suction casing 18 to the suction passage 23 as in the first embodiment. be introduced. At this time, hole 2
Since the circumferential component XQ of the suction flow path 23 of the flow X blown out from the nozzle 6 faces in the direction along the impeller rotation direction 17, the suction pipe 8
This acts to increase the circumferential velocity component of the air flow 16 flowing from the first stage compressor 1a to the first stage compressor 1a. As a result, similarly to the first embodiment, the impeller theoretical head Hth of the first-stage compressor 1a can be reduced accordingly, and the driving power of the first-stage compressor 1a can be reduced. In addition, since the axial component XP of the flow X of the flow X blown out from the hole 26 is substantially opposite to the flow 16 of the suction air in the suction flow path 23, a collision loss (pressure loss) occurs. The driving power of the compressor 1a can be reduced.

As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained.

In the second embodiment, the discharge passage 11 is connected to the suction casing 18 and the suction passage 2 is connected to the suction passage 18 through the hole 26 formed in the suction casing 18 from the chamber 25.
3 was blown out, but not limited to this.
1 may be connected to the suction casing 19, and the flow may be blown out to the suction channel 23 through a hole formed in the suction casing 19. In this case, a similar effect is obtained. These holes 26
Are not necessarily limited to a plurality, and at least one is sufficient.

A third embodiment of the present invention will be described with reference to FIGS. This embodiment is similar to the second embodiment.
This is another embodiment of the structure in which the other end of the air discharge passage 11 is connected to the suction casings 18 and 19 of the first-stage compressor 1a. Portions common to the first and second embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

FIG. 6 is a longitudinal sectional view showing the details of the joint between the air discharge passage 11 and the suction casings 18 and 19 of the first stage compressor 1a, which is a main part of this embodiment. 6 is a transverse sectional view taken along the line CC in FIG.

6 and 7, the suction casing 18 of the first stage compressor 1a is provided with a hole 36 at the outer periphery thereof, which is oriented in the circumferential direction of the suction casing 18.
Is connected to the air discharge passage 11. At this time, the hole 36
Are arranged so that a component XQ (in this case, almost equal to X) of the flow X blown out from the hole 36 in the circumferential direction of the suction passage is in a direction along the impeller rotation direction 17 (see FIG. 7). .

The structure other than the above is substantially the same as that of the first embodiment.

In the above configuration, during the no-load operation, air is introduced from the air discharge passage 11 into the suction passage 23 through the hole 36 of the suction casing 18 as in the second embodiment. At this time, the suction channel 2 of the flow X blown out from the hole 36
Since the three circumferential components XQ are oriented in the direction along the impeller rotation direction 17, the air flow 16 flowing from the suction pipe 8 to the first stage compressor 1a is swirled to increase the circumferential speed component. . In this manner, the same effects as in the second embodiment are obtained. Further, at this time, since the turning speed in the casing 18 is almost inversely proportional to the radius, when the turning flow is introduced from a large radius position as in the present embodiment, a larger turning speed is obtained at the impeller inlet portion than in other structures. There is also an effect that the driving power of the first-stage compressor 1a can be further reduced.

It goes without saying that a plurality of holes 36 may be provided.

A fourth embodiment of the present invention will be described with reference to FIG. This embodiment is an embodiment in a case where an electric motor that drives a compressor is cooled using air from a ventilation passage. Portions common to the first to third embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

FIG. 8 is a system diagram of the turbo compressor system according to the present embodiment, and corresponds to FIG. 1 of the first embodiment. 8 differs from the turbo compressor system according to the first embodiment shown in FIG. 1 in the following points. That is, a throttle portion 34 for adjusting the flow rate is provided downstream of the blow-off valve 4 in the blow-off passage 11, and a cooling pipe 29 provided with a check valve 30 branches from the throttle portion 34.
A cooling pipe 28 having a check valve 31 is also branched from the pipe 9 downstream of the intercooler 3a.
The cooling pipe 8 and the cooling pipe 29 are joined to form a cooling pipe 32 which is connected to a cooling passage 33 a in a motor 33 of a forced air cooling type.

The structure other than the above is substantially the same as that of the first embodiment.

In the above configuration, the cooling pipe 29,
A cooling pipe 32 is provided to branch off from the air discharge passage and guide a part of the air in the air discharge passage to the cooling passage of the electric motor.

Next, the operation of the turbo compressor system having the above configuration will be described.

During normal load operation, as in the first embodiment, the air sucked in from the suction pipe 8 is pressurized by the first stage compressor 1a, then cooled by the intermediate air cooler 3a, and compressed by the second stage compressor. Machine 1b. Second stage compressor 1b
Is further cooled by the second-stage (final-stage) air cooler 3b, passes through the check valve 5, enters the receiver tank 7, and is sent to the demand side process. At this time, a part of the air cooled by the intermediate air cooler 3a is guided to the motor cooling passage 33a through the cooling pipe 28, the check valve 31, and the cooling pipe 32, and is discharged to the atmosphere after cooling the motor 33. Is done.

On the other hand, during the no-load operation, as in the first embodiment, the blow-off valve 4 is opened and air is guided from the blow-off passage 11 to the chamber 14 (see FIGS. 2 and 3). Is introduced into the suction pipe 8 through the hole 15. At this time, a part of the air in the ventilation passage 11 flows to the cooling pipe 29 and the check valve 3
0, is guided to the motor cooling passage 33a through the cooling pipe 32 to cool the motor 33.

According to the present embodiment, the same effects as those of the first embodiment can be obtained. In addition, the blowing air during the no-load operation can be used for cooling the electric motor 33.

[0047]

According to the present invention, since the circumferential speed increasing means is provided at the connection portion of the other end of the air discharge passage with the suction side of the first stage compressor, noise due to air blow during no-load operation is suppressed. And maintenance costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of a turbo compressor system according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing details of a joint between an air discharge passage and a suction pipe in FIG. 1;

FIG. 3 is a transverse sectional view taken along the line AA in FIG. 2;

FIG. 4 is a longitudinal sectional view showing details of a joint between an air discharge passage and a suction casing of a first stage compressor, which is a main part of a second embodiment of the present invention.

FIG. 5 is a cross-sectional view taken along a line BB in FIG. 4;

FIG. 6 is a longitudinal sectional view showing details of a joint between an air discharge passage and a suction casing of a first stage compressor, which is a main part of a third embodiment of the present invention.

FIG. 7 is a transverse sectional view taken along the line CC in FIG. 6;

FIG. 8 is a system diagram of a turbo compressor system according to a fourth embodiment of the present invention.

[Explanation of symbols]

1a First-stage compressor 1b Second-stage compressor (final-stage compressor) 4 Blow-off valve 8 Suction pipe 10 Discharge pipe 11 Blow-off passage 12,13 Joint 14 Chamber (circumferential speed increasing means) 15 Hole (first 16 Original flow of suction air 17 Impeller rotation direction 18 and 19 Suction casing 21 Impeller 23 Suction channel 26 Hole (second air guide hole, circumferential speed increasing means) 29, 32 Cooling pipe 35 Suction filter 36 hole (second air guide hole, means for increasing circumferential speed)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuo Fukushima 603, Kandamachi, Tsuchiura-shi, Ibaraki Pref. Inside the Tsuchiura Plant, Hitachi, Ltd. Tsuchiura factory

Claims (5)

[Claims] 1. A suction pipe provided with a filter at a suction port, at least one stage turbo compressor connected to the suction pipe,
A discharge pipe connected to the discharge side of the last-stage compressor; a discharge passage connected at one end to the discharge pipe and the other end connected to the suction side of the first-stage compressor; A blow-off valve for opening and closing the air passage, and closing the blow-off valve during a load operation, and opening the blow-off valve during a no-load operation to discharge compressed air discharged from the last-stage compressor via a discharge pipe. Through the air discharge passage to the suction side of the first stage compressor, the other end of the air discharge passage at the connection with the first stage compressor suction side, during the no-load operation, A turbo compressor system comprising a circumferential speed increasing means for increasing a circumferential speed component of an air flow on the suction side of the first-stage compressor using air guided through an air discharge passage. 2. A turbo compressor system according to claim 1, wherein said circumferential speed increasing means communicates with said air discharge passage and surrounds a part of said suction pipe, and said inner pipe of said suction pipe. At least one first air guide hole provided in a wall portion and configured to supply air introduced into the chamber from the air discharge passage into the suction pipe,
Further, the first air guide hole is arranged in such a direction that a circumferential direction component of the air supplied into the suction pipe is in a direction along a rotation direction of an impeller of the turbo compressor. A turbo compressor system characterized by the above-mentioned. 3. The turbo compressor system according to claim 1, wherein said circumferential speed increasing means is provided in a suction casing of said first stage compressor, and transfers air from said air discharge passage to a suction flow in said suction casing. At least one to supply to the road
A second air guide hole, and the second air guide hole is configured to rotate the impeller of the turbo compressor when a circumferential component of the air supplied into the suction flow path in the suction flow path is rotated. A turbo compressor system, wherein the turbo compressor system is arranged so as to be oriented along a direction. 4. The turbo-compressor system according to claim 2, wherein said first or second air guide hole is configured such that an axial component of air supplied into said suction pipe or said suction passage is equal to said suction port. A turbo compressor system, wherein the turbo compressor system is arranged in a direction substantially opposite to an air flow in a pipe or a suction passage. 5. The turbo compressor system according to claim 1, wherein an electric motor for driving said at least one stage turbo compressor and a part of the air in said air discharge passage branched from said air discharge passage. And a cooling pipe for guiding the cooling water to a cooling passage of the electric motor.