COMPRESSOR SYSTEM

Abstract

A compressor system includes a compressor that includes an impeller configured to compress a working fluid by rotation. The compressor includes a housing in which an inflow flow path and a discharge flow path are formed, a guide vane that is provided in the inflow flow path and has an angle that is changeable, a diffuser vane that is provided in the discharge flow path and has an angle that is changeable, and a control unit configured to control angles of the guide vane and the diffuser vane. The control unit controls an angle of at least one of the guide vane and the diffuser vane based on a requested PQ characteristic value and a rotational speed of the impeller.

Description

TECHNICAL FIELD

The present invention relates to a compressor system.

Priority is claimed on Japanese Patent Application No. 2015-054250, filed Mar. 18, 2015, the content of which is incorporated herein by reference.

BACKGROUND ART

A compressor system in which a motor and a compressor are integrated includes a compressor configured to compress a gas such as air or the like and a motor configured to drive the compressor. In the compressor system, a rotation shaft that extends from a casing of the compressor and a rotation shaft of a motor that similarly extends from a casing of the motor are connected. The rotation of the motor is transmitted to the compressor. The rotation shafts of the motor and the compressor are supported by a plurality of bearings and thus reliably rotate.

Such a compressor system is used for, for example, a subsea production system as in Non Patent Literature 1 or a Floating Production Storage and Offloading (FPSO) unit as in Non Patent Literature 2. When the compressor system is used for the subsea production system, the compressor system is installed in the seabed. The compressor system sends production fluids mixed with crude oils and natural gases that are drawn from production wells drilled to a depth of several thousand meters in the seabed to the sea surface. When the compressor system is used for the FPSO unit, the compressor system is installed in a marine facility such as a ship.

CITATION LIST

Non Patent Literature

[Non Patent Literature 1]

Mitsubishi Heavy Industries Technical Review Vol. 34 No. 5 P310-P313

[Non Patent Literature 2]

Turbomachinery International September/October 2014 P18-P24

SUMMARY OF INVENTION

Technical Problem

Incidentally, in a compressor system used for the subsea production system and the FPSO unit, production fluids mixed with crude oils and natural gases drawn from production wells in the seabed flow into the compressor as fluids. There is a possibility of characteristics of the production fluids being changed due to a change of a content of oil of crude oil or the like during drawing. When characteristics of production fluids change, the range in which the compressor can operate changes. As a result, operation conditions of the compressor change.

The present invention provides a compressor system capable of responding to changing operation conditions.

Solution to Problem

In order to address the above problems, the present invention proposes the following solutions.

A compressor system according to a first aspect of the present invention includes a motor including a rotor configured to rotate about an axis and a stator that is disposed on an outer circumference side of the rotor; and a compressor including an impeller that rotates together with the rotor and compresses a working fluid, wherein the compressor includes a housing in which an inflow flow path through which a working fluid flows into the impeller and a discharge flow path through which a working fluid pressure-fed by the impeller circulates are formed; a guide vane that is provided in the inflow flow path and has an angle that is changeable; a diffuser vane that is provided in the discharge flow path and has an angle that is changeable; and a control unit configured to control angles of the guide vane and the diffuser vane, and wherein the control unit controls an angle of at least one of the guide vane and the diffuser vane based on requested PQ characteristic values that are required pressure and flow rate values and a rotational speed of the impeller.

In such a configuration, it is possible to control an angle of at least one of the guide vane and the diffuser vane based on the requested PQ characteristic value and the rotational speed of the impeller. Therefore, it is possible to decrease at least one of an angle at which a working fluid that flows into the impeller from the inflow flow path flows and an angle at which a working fluid that flows into the discharge flow path from the impeller flows. Therefore, a surge control line can be changed to improve PQ characteristics during operation and it is possible to increase an operation range of the compressor.

In a compressor system according to a second aspect of the present invention, in the first aspect, when a rotational speed of the impeller is less than a predetermined reference, the control unit may control an angle of the guide vane so that a relative angle with respect to a direction in which the working fluid that flows into the impeller from the inflow flow path flows becomes smaller.

In such a configuration, when a rotational speed of the impeller is less than a predetermined reference, a relative angle of the guide vane with respect to a direction in which a working fluid that flows into the impeller from the inflow flow path which is a side in which a working fluid flows into the impeller flows becomes smaller. Therefore, it is possible to efficiently improve PQ characteristics. As a result, when an angle of the guide vane is adjusted, it is possible to efficiently increase an operation range of the compressor in a low pressure and low flow rate area.

In a compressor system according to a third aspect of the present invention, in the first aspect, when a rotational speed of the impeller is greater than a predetermined reference, the control unit may control an angle of the diffuser vane so that a relative angle with respect to a direction in which the working fluid that flows into the discharge flow path from the impeller flows becomes smaller.

In such a configuration, when a rotational speed of the impeller is greater than a predetermined reference, a relative angle of the diffuser vane with respect to an angle at which a working fluid that flows into the discharge flow path which is a side in which a working fluid from the impeller is discharged flows becomes smaller. Therefore, it is possible to efficiently improve PQ characteristics. As a result, it is possible to efficiently increase an operation range of the compressor in a high pressure and high flow rate area.

In a compressor system according to a fourth aspect of the present invention, in any one of the first to third aspects, when the requested PQ characteristic value satisfies a requirement of a predetermined reference, the control unit may control an angle of the guide vane so that a relative angle with respect to a direction in which the working fluid that flows into the impeller from the inflow flow path becomes smaller.

In such a configuration, it is possible to change an angle to improve PQ characteristics only as necessary and it is possible to efficiently increase an operation range of the compressor.

In a compressor system according to a fifth aspect of the present invention, in any one of the first to third aspects, when the requested PQ characteristic value satisfies a requirement of a predetermined reference, the control unit may control an angle of the diffuser vane so that a relative angle with respect to a direction in which the working fluid that flows into the discharge flow path from the impeller flows becomes smaller.

In such a configuration, it is possible to change an angle to improve PQ characteristics only as necessary and it is possible to efficiently increase an operation range of the compressor.

Advantageous Effects of Invention

According to the compressor system of the present invention, when an angle of at least one of the guide vane and the diffuser vane is controlled, it is possible to respond to changing operation conditions by widening an operation range of the compressor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram describing a compressor system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an internal structure of a compressor according to an embodiment of the present invention.

FIG. 3 is a diagram of a relationship between a flow rate and a pressure in a compressor according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment according to the present invention will be described with reference to FIG. 1 to FIG. 3.

A compressor system 1 is provided in the seabed for a subsea production system that is one for ocean oil and gas field development methods and is provided on the sea surface for a Floating Production Storage and Offloading (FPSO) unit. The compressor system 1 pressure-feeds a production fluid such as oils and gases harvested from oil gas field production wells that are located several hundreds to thousands of meters from the seabed as a working fluid.

As shown in FIG. 1, the compressor system 1 includes a compressor 2, a motor 3, a bearing 4, a casing 5, and a control unit 6. The compressor 2 includes a shaft 21 that extends in an O axis direction (in a horizontal direction in FIG. 1) as a rotation shaft. The motor 3 includes a rotor 31 that is directly connected to the shaft 21. The bearing 4 supports the shaft 21. The casing 5 accommodates the motor 3 and the compressor 2. The control unit 6 controls the motor 3 and the compressor 2.

The compressor 2 is accommodated inside the casing 5. The compressor 2 compresses a working fluid when the shaft 21 rotates about an O axis together with the rotor 31. The compressor 2 of this embodiment includes the shaft 21, an impeller 22, and the housing 23. The shaft 21 extends in the O axis direction. The impeller 22 is fixed to an outer circumference surface of the shaft 21 and compresses a working fluid by rotating together with the rotor 31. The housing 23 covers the impeller 22 from the outside.

The shaft 21 is a rotation shaft that extends in the O axis direction. The shaft 21 is supported by the casing 5 to be rotatable about the O axis. The shaft 21 passes through the housing 23 in the O axis direction. The shaft 21 has ends both of which extend from the housing 23. The shaft 21 extends in the O axis direction in the casing 5 to be described below.

The impeller 22 rotates together with the shaft 21 and compresses a working fluid that passes an impeller flow path 22a formed therein to generate a compressed fluid. A plurality of impellers 22 are fixed to the outer circumference surface of the shaft 21 side by side with spaces therebetween in the O axis direction. Also, FIG. 1 shows an example in which the plurality of impellers 22 is provided. However, in the compressor 2, at least one impeller 22 may be provided.

As shown in FIG. 2, through the impeller flow path 22a, a working fluid is circulated from an inlet portion of the impeller 22 to an outlet portion of the impeller 22. The inlet portion of the impeller 22 is formed at an end that faces an upstream side (the right side in FIG. 1 and FIG. 2) that is one side of the impeller 22 in the O axis direction. The outlet portion of the impeller 22 is formed at an end that faces outward in a radial direction with respect to the O axis of the impeller 22.

The housing 23 is an exterior of the compressor 2. The housing 23 accommodates the impeller 22 therein. The housing 23 is accommodated inside the casing 5. In the housing 23, a plurality of internal spaces 23a whose diameters are repeatedly reduced and increased are provided. The impeller 22 is accommodated in the internal space 23a. In the internal space 23a, the impeller 22 is disposed with a predetermined space between itself and the housing 23. In the housing 23, a housing flow path 24 is formed. Through the housing flow path 24, a working fluid is circulated from the impeller 22 that is disposed on an upstream side in the O axis direction to the impeller 22 adjacent on a downstream side (the left side in FIG. 1 and FIG. 2) that is the other side in the O axis direction.

As shown in FIG. 2, the housing flow path 24 includes a suction flow path 25, an intermediate flow path 26, and a discharge flow path (not shown). The suction flow path 25, through which a working fluid flows into the impeller 22 from the outside, is disposed on the furthest upstream side in the O axis direction. The intermediate flow path 26 is formed between the plurality of impellers 22. Through the discharge flow path (not shown), a working fluid compressed by the impeller 22 disposed on the furthest downstream side in the O axis direction is discharged to the outside.

The suction flow path 25 is formed at a position on the upstream side relative to the impeller 22 that is disposed on the furthest upstream side in the O axis direction. The suction flow path 25 is an inflow flow path through which a working fluid flows into the impeller 22 disposed on the furthest upstream side in the O axis direction. The suction flow path 25 extends inward in the radial direction from an opening formed in a circumferential direction on the upstream side in the O axis direction of the housing 23. Through the suction flow path 25, a working fluid is circulated to an inlet of the impeller flow path 22a. An inlet guide vane 251 (a guide vane) is provided in the suction flow path 25. The inlet guide vane 251 changes a direction of a working fluid suctioned from the outside of the housing 23 to a desired direction and guides the working fluid to the impeller flow path 22a.

The inlet guide vane 251 has an angle that is changeable by an operating mechanism (not shown). The desired direction in the inlet guide vane 251 is, for example, a direction in which pre-rotation is applied to the working fluid suctioned from the outside. The desired direction in the inlet guide vane 251 is, for example, a direction inclined toward the front side of the impeller 22 in a rotation direction as it advances in the radial direction. The inlet guide vane 251 of this embodiment has an angle that is adjusted based on a signal from the control unit 6 such that a relative angle with respect to a direction in which a working fluid that flows into the impeller flow path 22a flows becomes smaller.

The intermediate flow path 26 is formed to connect adjacent impellers 22 in the O axis direction. The intermediate flow path 26 does not communicate with the outside of the housing 23 and is formed inside the housing 23. The intermediate flow path 26 includes a diffuser flow path 27 and a return flow path 28. The diffuser flow path 27 extends outward in the radial direction from an outlet portion of the impeller flow path 22a. The return flow path 28 is connected to the diffuser flow path 27 and extends to the inlet portion of the impeller flow path 22a of the adjacent impeller 22.

The diffuser flow path 27 has an inlet that faces the outlet portion of the impeller flow path 22a. Through the diffuser flow path 27, a working fluid discharged from the impeller flow path 22a is circulated outward in the radial direction. The diffuser flow path 27 is a discharge flow path through which a working fluid pressure-fed by the impeller 22 circulates. In the diffuser flow path 27, a diffuser vane 271 is provided. The diffuser vane 271 changes a direction of the working fluid discharged from the impeller flow path 22a to a desired direction.

The diffuser vane 271 has an angle that is changeable by an operating mechanism (not shown). The desired direction in the diffuser vane 271 is a direction in which a dynamic pressure of a circulating working fluid is restored as a static pressure. The desired direction in the diffuser vane 271 is a direction inclined toward the front side of the impeller 22 in a rotation direction as it advances in the radial direction. The diffuser vane 271 of this embodiment has an angle that is adjusted based on a signal from the control unit 6 such that a relative angle with respect to a direction in which a working fluid that flows into the diffuser flow path 27 from the impeller flow path 22a flows becomes smaller.

The return flow path 28 is an inflow flow path through which a working fluid that has circulated in the diffuser flow path 27 flows into the impeller flow path 22a. The return flow path 28 includes a curved flow path 281 and a linear flow path 282. The curved flow path 281 is connected to an outer end of the diffuser flow path 27 in the radial direction. The linear flow path 282 is connected to an end of the curved flow path 281.

The curved flow path 281 is continuously formed with respect to the outside of the diffuser flow path 27 in the radial direction. The curved flow path 281 extends outward in the radial direction and then curves inward in the radial direction. In the curved flow path 281, a flow of the working fluid that moves outward in the radial direction is changed to a flow that moves inward in the radial direction.

The linear flow path 282 extends inward in the radial direction from the curved flow path 281 to an inlet portion of the impeller flow path 22a. The linear flow path 282 is continuously formed with respect to a side opposite to a portion connected to the diffuser flow path 27 of the curved flow path 281. In the linear flow path 282, a return vane 282a that changes a direction of a working fluid that has circulated in the diffuser flow path 27 to a desired direction is provided.

As shown in FIG. 1, the motor 3 is accommodated in the casing 5 with a space in the O axis direction between itself and the compressor 2. The motor 3 includes a rotor 31 and a stator 32. The rotor 31 is fixed to be integrated with the shaft 21. The stator 32 is disposed on an outer circumference side of the rotor 31.

The rotor 31 is integrated with the shaft 21 and rotatable about the O axis. The rotor 31 is directly connected to an outer circumference side of the shaft 21, which is the outside in a circumferential direction with respect to the O axis so that it integrally rotates with the shaft 21 of the compressor 2 without intervening of gears and the like. The rotor 31 includes, for example, a rotor core (not shown) in which an induced current flows when the stator 32 generates a rotating magnetic field.

A gap in the circumferential direction is provided between the stator 32 and the rotor 31 to cover the rotor 31 from the outer circumference side. The stator 32 includes a plurality of stator cores (not shown) that are disposed in, for example, the circumferential direction of the rotor 31, and a stator winding (not shown) wound on the stator core. When a current flows from the outside, the stator 32 generates a rotating magnetic field and rotates the rotor 31. The stator 32 is fixed into the casing 5.

The bearing 4 is accommodated inside the casing 5 and rotatably supports the shaft 21. The bearing 4 of this embodiment includes a plurality of journal bearings 41 and thrust bearings 42.

The journal bearing 41 supports a load on the shaft 21 in the radial direction. Journal bearings 41 are disposed at both ends of the shaft 21 in the O axis direction to sandwich the motor 3 and the compressor 2 in the O axis direction. The journal bearing 41 is also disposed between an area in which the compressor 2 is provided and an area in which the motor 3 is provided, which is on the motor 3 side relative to a sealing member 51 to be described below.

The thrust bearing 42 supports a load on the shaft 21 in the O axis direction through a thrust collar 21a that is formed at the shaft 21. The thrust bearing 42 is disposed between the area in which the compressor 2 is provided and the area in which the motor 3 is provided and is on the compressor 2 side relative to the sealing member 51 to be described below.

The casing 5 accommodates the compressor 2 and the motor 3 therein. The casing 5 has a cylindrical shape along the O axis. An inner surface of the casing 5 protrudes toward the shaft 21 between the compressor 2 and the motor 3 in the O axis direction. The casing 5 is provided on a portion from which the sealing member 51 sealing a gap between the area in which the compressor 2 is provided and the area in which the motor 3 is provided protrudes.

The control unit 6 controls the compressor 2 and the motor 3 so that the compressor 2 is operated according to predetermined operation conditions. The control unit 6 controls angles of the inlet guide vane 251 and the diffuser vane 271. The control unit 6 controls the rotational speed of the rotor 31 of the motor 3. As shown in FIG. 2, the control unit 6 includes an input unit 61, a determination unit 62, and an output unit 63. In the input unit 61, a requested PQ characteristic value that is a requested pressure and flow rate value and a requested rotational speed that is a requested rotational speed of the impeller 22 are input. The determination unit 62 determines whether the input requested PQ characteristic value and the requested rotational speed satisfy requirements of predetermined references. The output unit 63 sends a signal to the motor 3, the inlet guide vane 251, and the diffuser vane 271 based on the determination result of the determination unit 62.

The input unit 61 outputs the input requested PQ characteristic value and requested rotational speed to the determination unit 62.

The determination unit 62 determines whether the requested rotational speed satisfies a requirement of a predetermined reference and determines whether the requested PQ characteristic value is within an initial operation range. The determination unit 62 sends an instruction to the output unit 63 of an extent to which to adjust an angle of the inlet guide vane 251 or the diffuser vane 271 based on the determination result.

Here, the initial operation range is a range in which the compressor 2 in an initial setting state can operate without causing a surge. In curves showing a relationship between a pressure and a flow rate of the compressor 2 shown in FIG. 3, the initial operation range indicates an area on the right side relative to surge control lines SCL 11 and SCL 12 and surge control lines SCL 21 and SCL 22. The surge control lines SCL 11 and SCL 12 are determined by the inlet guide vane 251 and the diffuser vane 271 whose angles are set to initial values. The surge control lines SCL 21 and SCL 22 are determined by the inlet guide vane 251 and the diffuser vane 271 after angles are changed, which will be described below. Also, in an area on the left side relative to such surge control lines, surge occurs.

Specifically, the determination unit 62 of this embodiment determines whether the input requested rotational speed is less than a predetermined first reference. The determination unit 62 determines whether the input requested rotational speed is greater than a predetermined second reference.

Here, the first reference refers to a rotational speed at which the compressor 2 operates in an area in which a pressure and a flow rate are lower than those in a state at 100% of the rotational speed when a rotational speed during a rated operation is set to 100%. On the other hand, the second reference refers to a rotational speed at which the compressor 2 operates in an area in which a pressure and a flow rate are higher than those in a state at 100% of the rotational speed.

In this embodiment, the first reference is set to 100% of the rotational speed. In this embodiment, the second reference is set to 110% of the rotational speed.

When the input requested rotational speed is less than 100% of the rotational speed serving as the first reference, the determination unit 62 sends an instruction to the output unit 63 to adjust the inlet guide vane 251. When it is determined that the requested rotational speed is less than the first reference, the determination unit 62 determines whether the input requested PQ characteristic value is within an area on the right side relative to the low side surge control line SCL 12 of an area having a low pressure and a low flow rate in the initial operation range. Therefore, for example, when the requested PQ characteristic value is a value of an area α in FIG. 3, it is determined that the requested PQ characteristic value exceeds the low side surge control line SCL 12. In this case, the determination unit 62 sends an instruction to the output unit 63 to adjust an angle of the inlet guide vane 251 so that a relative angle with respect to a direction in which a working fluid that flows into the impeller flow path 22a from the suction flow path 25 flows becomes smaller.

When the input requested rotational speed is greater than 110% of the rotational speed serving as the second reference, the determination unit 62 sends an instruction to the output unit 63 to adjust the diffuser vane 271. When it is determined that the requested rotational speed is greater than the second reference, the determination unit 62 determines whether the input requested PQ characteristic value is within an area on the right side relative to the high side surge control line SCL 11 of an area having a high pressure and a high flow rate in the initial operation range. Therefore, for example, when the requested PQ characteristic value is a value of an area 13 in FIG. 3, it is determined that the requested PQ characteristic value exceeds the high side surge control line SCL 11. In this case, the determination unit 62 sends an instruction to the output unit 63 to adjust an angle of the diffuser vane 271 so that a relative angle with respect to a direction in which a working fluid that flows into the diffuser flow path 27 from the impeller flow path 22a flows becomes smaller.

When the input requested rotational speed is greater than the first reference and less than the second reference, the determination unit 62 sends an instruction to the output unit 63 not to adjust an angle of the inlet guide vane 251 or the diffuser vane 271. When the input requested PQ characteristic value does not exceed the initial operation range, the determination unit 62 sends an instruction to the output unit 63 not to adjust an angle of the inlet guide vane 251 or the diffuser vane 271.

Based on the requested rotational speed input from the input unit 61 through the determination unit 62, the output unit 63 sends an instruction to the motor 3 to change a rotational speed of the rotor 31. Based on the determination result of the determination unit 62, the output unit 63 sends an instruction to the inlet guide vane 251 or the diffuser vane 271 to change an angle. Also, an amount of change in the angle of the inlet guide vane 251 or the diffuser vane 271 may be appropriately set based on a difference between the requested PQ characteristic value and a current PQ characteristic value.

In this embodiment, when the instruction from the output unit 63 is received, an angle of the inlet guide vane 251 is adjusted. Therefore, as shown in FIG. 3, a position of the low side surge control line SCL 12 in a low pressure and low flow rate area is changed to that of SCL 22. When the instruction from the output unit 63 is received, an angle of the diffuser vane 271 is adjusted. Therefore, a position of the high side surge control line SCL 11 in a high pressure and high flow rate area is changed to that of SCL 12.

According to the compressor system 1 described above, based on the requested PQ characteristic value and requested rotational speed input to the input unit 61 of the control unit 6, a current is supplied to the stator 32 by an external device such as a generator (not shown). A rotating magnetic field is generated based on the supplied current, and the rotor 31 of the motor 3 starts rotating together with the shaft 21 at the requested rotational speed. When the shaft 21 rotates at a high speed, in the compressor 2, a working fluid that flows into the compressor 2 from the upstream side in the O axis direction is compressed by the impeller 22 that rotates together with the shaft 21, and a compressed fluid for which the requested PQ characteristic value is satisfied is discharged from the downstream side in the O axis direction.

Here, for example, when a quantity of state of a content of oil in a production fluid while the compressor system 1 operates varies, characteristics of the working fluid that flows into the compressor 2 change and a discharge pressure of the compressor 2 changes. Therefore, the requested PQ characteristic value and the requested rotational speed are input to the input unit 61 of the control unit 6 such that a constant discharge pressure of the compressor 2 is maintained. When the requested PQ characteristic value and the requested rotational speed are input, the output unit 63 sends an instruction to the motor 3 to change a rotational speed of the rotor 31 according to the requested rotational speed. As a result, a rotational speed of the impeller 22 is adjusted through the rotor 31. At the same time, in the determination unit 62, when it is determined that the requested rotational speed is less than the first reference, it is determined whether the requested PQ characteristic value exceeds the low side surge control line SCL 12. When the requested rotational speed is less than the first reference and the requested PQ characteristic value exceeds the low side surge control line SCL 12, the determination unit 62 sends a signal to the output unit 63 to adjust an angle of the inlet guide vane 251. The inlet guide vane 251 that has received the signal from the output unit 63 adjusts an angle such that a relative angle with respect to a direction in which a working fluid that flows into the impeller flow path 22a from the suction flow path 25 flows becomes smaller. When an angle of the inlet guide vane 251 is changed, a position of the low side surge control line SCL 12 is changed to that of SCL 22. At the same time, an operation area of 110% of the rotational speed is changed from a line L111 to a line L112. Therefore, it is possible to improve PQ characteristics in a low pressure and low flow rate area.

When it is determined that the requested rotational speed is greater than the second reference, the determination unit 62 determines whether the requested PQ characteristic value exceeds the high side surge control line SCL 11. When the requested rotational speed is greater than the second reference and the requested PQ characteristic value exceeds the high side surge control line SCL 11, the determination unit 62 sends a signal to the output unit 63 to adjust an angle of the diffuser vane 271. The diffuser vane 271 that has received the signal from the output unit 63 adjusts an angle such that a relative angle with respect to a direction in which a working fluid that flows into the diffuser flow path 27 from the impeller flow path 22a flows becomes smaller. When an angle of the diffuser vane 271 is changed, a position of the high side surge control line SCL 11 is changed to that of the SCL 12. At the same time, an operation area of 110% of the rotational speed is changed from the line L111 to the line L112. Therefore, it is possible to improve PQ characteristics in a high pressure and high flow rate area.

That is, a surge control line can be changed to improve PQ characteristics during operation. Therefore, even if a quantity of state of a working fluid that flows in the impeller flow path 22a is changed, it is possible for the compressor 2 to perform an operation for setting a discharge pressure to be constant over a wide range. Accordingly, it is possible to respond to changing operation conditions by widening an operation range of the compressor 2.

When the requested rotational speed is low, the impeller 22 rotates at a low rotational speed. Therefore, the compressor 2 operates in a low pressure and low flow rate area. That is, when the requested rotational speed is low, efficiency of compression of a working fluid by the impeller 22 is low. Therefore, a volumetric flow rate of the working fluid that circulates in the impeller flow path 22a increases. Therefore, when the requested rotational speed is low, a direction in which a working fluid that flows in the impeller flow path 22a flows greatly influences an operation range of the compressor 2. Therefore, when the requested rotational speed is less than the predetermined first reference, a relative angle of the inlet guide vane 251 with respect to a direction in which a working fluid that flows into the impeller flow path 22a from the suction flow path 25 which is a side in which a working fluid flows into the impeller flow path 22a flows becomes smaller. Therefore, it is possible to efficiently improve PQ characteristics. That is, when an angle of the inlet guide vane 251 is adjusted, it is possible to increase an operation range of the compressor 2 more efficiently than when the diffuser vane 271 is adjusted in a low pressure and low flow rate area.

When the requested rotational speed is high, the compressor 2 operates in a high pressure and high flow rate area. That is, when the requested rotational speed is high, efficiency of compression of the working fluid is high. Therefore, a volumetric flow rate of a working fluid that circulates in the impeller flow path 22a becomes smaller. Therefore, in a high pressure and high flow rate area, an angle at which a working fluid discharged from the impeller flow path 22a flows into the diffuser flow path 27 greatly influences an operation range of the compressor 2. Therefore, when the requested rotational speed is greater than the predetermined second reference, a relative angle of the diffuser vane 271 with respect to an angle at which a working fluid that flows into the diffuser flow path 27 which is a discharge side of a working fluid from the impeller flow path 22a flows becomes smaller. Therefore, it is possible to efficiently improve PQ characteristics. That is, when an angle of the diffuser vane 271 is adjusted, it is possible to increase an operation range of the compressor 2 more efficiently than when the inlet guide vane 251 is adjusted in a high pressure and high flow rate area.

Angles of the inlet guide vane 251 and the diffuser vane 271 are determined only when the requested PQ characteristic value exceeds the initial operation range. Therefore, it is possible to change an angle to improve PQ characteristics only as necessary and it is possible to efficiently increase an operation range of the compressor 2.

The embodiments of the present invention have been described in detail above with reference to the drawings, but configurations and combinations thereof in the embodiments are only examples, and additions, omissions, substitutions and other modifications of the configurations can be made without departing from the scope of the present invention. In addition, the present invention is not limited to the embodiments and is only limited by the scope of the appended claims.

Note that the guide vane is not limited to the inlet guide vane 251 that is provided in the suction flow path 25 as in this embodiment. Any guide vane that is provided in the inflow flow path and can change a direction of a working fluid that flows in the impeller flow path 22a to a desired direction may be used. For example, the guide vane may be the return vane 282a that is provided in the linear flow path 282 of the return flow path 28.

While a configuration in which the inlet guide vane 251 serving as a guide vane and the diffuser vane 271 are disposed together is used in this embodiment, the present invention is not limited to such a configuration. That is, in the compressor 2, only the guide vane may be provided or only the diffuser vane 271 may be provided.

When the plurality of impellers 22 are provided, the guide vane and the diffuser vane 271 are not necessarily provided in all of the impellers 22. The guide vane and the diffuser vane 271 may be disposed only around the impeller 22 of a stage for which an operation range is to be adjusted.

In the determination unit 62 of this embodiment, as a reference for determining whether a value is within a predetermined operation range, the first reference and the second reference that are different from each other are used, and the present invention is not limited thereto. For example, one reference may be used to determine whether a value is within the predetermined operation range.

INDUSTRIAL APPLICABILITY

According to the above compressor system, when an angle of at least one of the guide vane and the diffuser vane is controlled, it is possible to respond to changing operation conditions by widening an operation range of the compressor.

REFERENCE SIGNS LIST

1 Compressor system

O Axis

2 Compressor

21 Shaft

22 Impeller

22a Impeller flow path

23 Housing

23a Internal space

24 Housing flow path

25 Suction flow path

251 Inlet guide vane

26 Intermediate flow path

27 Diffuser flow path

271 Diffuser vane

28 Return flow path

281 Curved flow path

282 Linear flow path

282a Return vane

3 Motor

31 Rotor

32 Stator

33 Gap

4 Bearing

41 Journal bearing

42 Thrust bearing

5 Casing

51 Sealing member

6 Control unit

61 Input unit

62 Determination unit

63 Output unit

Claims

1. A compressor system comprising:

a motor including a rotor configured to rotate about an axis and a stator disposed on an outer circumference side of the rotor; and

a compressor including an impeller rotating together with the rotor and compressing a working fluid,

wherein the compressor includes

a housing in which an inflow flow path through which a working fluid flows into the impeller and a discharge flow path through which a working fluid pressure-fed by the impeller circulates are formed;

a guide vane provided in the inflow flow path and having an angle that is changeable;

a diffuser vane provided in the discharge flow path and having an angle that is changeable; and

a control unit configured to control angles of the guide vane and the diffuser vane, and

wherein the control unit controls an angle of the guide vane based on a requested PQ characteristic value that is a requested pressure and flow rate value and a rotational speed of the impeller.

2. The compressor system according to claim 1,

wherein, when a rotational speed of the impeller is less than a predetermined reference, the control unit controls an angle of the guide vane so that a relative angle with respect to a direction in which the working fluid flowing into the impeller from the inflow flow path flows becomes smaller.

3. (canceled)

4. The compressor system according to claim 1,

wherein, when the requested PQ characteristic value satisfies a requirement of a predetermined reference, the control unit controls an angle of the guide vane so that a relative angle with respect to a direction in which the working fluid flowing into the impeller from the inflow flow path flows becomes smaller.

5. (canceled)

6. A compressor system comprising:

a motor including a rotor configured to rotate about an axis and a stator disposed on an outer circumference side of the rotor; and

a compressor including an impeller rotating together with the rotor and compressing a working fluid,

wherein the compressor includes

a housing in which an inflow flow path through which a working fluid flows into the impeller and a discharge flow path through which a working fluid pressure-fed by the impeller circulates are formed;

a guide vane provided in the inflow flow path and having an angle that is changeable;

a diffuser vane provided in the discharge flow path and having an angle that is changeable; and

a control unit configured to control angles of the guide vane and the diffuser vane, and

wherein the control unit controls an angle of at least one of the guide vane and the diffuser vane based on a requested PQ characteristic value that is a requested pressure and flow rate value and a rotational speed of the impeller, and

wherein, when a rotational speed of the impeller is less than a predetermined reference, the control unit controls an angle of the guide vane so that a relative angle with respect to a direction in which the working fluid flowing into the impeller from the inflow flow path flows becomes smaller.