JP2008144725A - Centrifugal compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal compressor with simple structure, giving a swirl flow in a circumferential direction of a main shaft with respect to fluid flowing therein. <P>SOLUTION: The centrifugal compressor 10 performing compression by rotating an impeller 2 has a chamber-type inlet suction casing 4 including a suction passage 3 supplying fluid to the impeller 2. A cylindrical part 4a as a suction port is disposed to the inlet suction casing 4. A unit pipe 6 with butterfly type IGV is installed to give the swirl flow to the fluid when the fluid is supplied from a radial direction of the main shaft 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a centrifugal compressor that compresses a fluid by rotation of an impeller, and more particularly, to a centrifugal compressor that supplies a compressed fluid to a turbo refrigerator or a plant.

  Conventionally, as a refrigeration apparatus for air conditioning equipment that circulates cooled cold water, a turbo refrigerator that cools cold water by exchanging heat with a refrigerant compressed by a compressor has been used. In this turbo refrigerator, a centrifugal compressor that compresses a refrigerant by rotation of an impeller is used as a compressor that compresses a refrigerant that exchanges heat with cold water. And a centrifugal compressor compresses the refrigerant | coolant which is the fluid suck | inhaled from the suction inlet by rotating the rotating shaft provided with the impeller, Then, it discharges | emits to the condenser which condenses and liquefies a refrigerant | coolant.

  As such a centrifugal compressor, the present applicant, in a multistage centrifugal compressor provided with a plurality of impellers, has a movable inlet guide vane (IGV) that controls the flow rate of the refrigerant sucked from the suction port. Inlet Guide Vane) is proposed (see Patent Document 1). In the centrifugal compressor of Patent Document 1, a movable IGV is provided at the suction port, and is movable between a fully open position that is substantially parallel to the refrigerant flow direction and a fully closed position that is substantially perpendicular to the refrigerant flow direction. The amount of inflow from the suction port is adjusted by adjusting the valve opening by the type IGV.

  Further, in the centrifugal compressor of Patent Document 1, the suction port is provided on the tip end side of the shaft for rotating the impeller, and the opening direction is provided in a direction parallel to the shaft. Such a centrifugal compressor is used for a small refrigerator having a small capacity. On the other hand, in a centrifugal compressor used for a large-sized refrigerator having a large capacity, the direction of opening is a direction perpendicular to the shaft, and the suction that bends at the tip side of the shaft and induces the refrigerant Many have mouths. FIG. 12 shows a configuration in the vicinity of a suction port of a centrifugal compressor used in such a large refrigerator or plant.

  As shown in FIG. 12, a conventional centrifugal compressor used in a large refrigerator or a plant has an impeller 2 with respect to the axial direction of a main shaft 1 on which an impeller 2 is installed on the outer peripheral surface. On the upstream side, the suction flow path 3 is formed so that the diameter becomes wider toward the upstream side. And the chamber type inlet suction casing 4 is comprised so that the space containing this suction flow path 3 may be provided. The inlet suction casing 4 is provided with a cylindrical portion 4a that is opened upward and extends upward, and a ring-shaped inlet flange 4b that extends to the outer peripheral side of the cylindrical portion 4a at the tip of the cylindrical portion 4a. Is provided.

  The suction flow path 3 is provided with a plurality of movable IGVs 50 in the circumferential direction of the main shaft 1, and the angle of the movable IGV 50 is changed with respect to the axial direction of the main shaft 1 (fluid flowing direction). An IGV movable mechanism 51 that is rotated to change the angle of the movable IGV 50 and an IGV drive shaft 52 that is connected to the IGV movable mechanism 51 from the outside of the casing 4 and transmits the rotation angle of the movable IGV 50 are provided. .

  In this conventional centrifugal compressor, when a fluid flows from the upper inlet flange 4b, the sucked fluid circulates in the inlet suction casing 4 in the circumferential direction of the main shaft 1 and is provided in the inlet suction casing 4. It flows into the suction channel 3. At this time, since the angle set from the outside is transmitted to the IGV movable mechanism 51 through the IGV drive shaft 52, the movable IGV 50 is rotated by the IGV movable mechanism 51, and the angle with respect to the axial direction is set to the set angle. The

  Then, when the fluid flows into the suction flow path 3 by the movable IGV 50 and further, the fluid flowing into the suction flow path 3 is compressed by the rotation of the impeller 2 and discharged to the diffuser 5 on the downstream side, the downstream from the diffuser 5 On the side, the kinetic energy is converted to pressure energy by reducing the velocity of the fluid flow. The fluid compressed in this way is supplied to an impeller provided in the next stage in a multi-stage centrifugal compressor, and is guided to an exhaust port for exhausting to the outside in a single-stage centrifugal compressor.

As shown in FIG. 12, by providing the movable IGV 50, the swirl flow added to the upstream side of the impeller 2 can be changed, and the operation flow range can be controlled in an enlarged manner. That is, by changing the angle of the movable IGV 50, the magnitude of the swirling flow is changed, and the surge point of the compressor shifts to the smaller flow rate side as the swirling flow with respect to the rotation direction of the impeller 2 increases. As a result, the entire flow rate operating range of the compressor is shifted to the small flow rate side, and a wide operating flow rate range is obtained.
JP 2003-307197 A JP 2000-314396 A

  However, when a plurality of movable IGVs 50 are provided in the circumferential direction as in the centrifugal compressor of FIG. 12, it is necessary to provide the IGV movable mechanism 51 and the IGV drive shaft 52 for each movable IGV 50. The IGV movable mechanism 51 and the IGV drive shaft 52 have a complicated structure and a large number of parts. Therefore, the structure in the inlet suction casing 4 becomes complicated, and as a result, the manufacturing process becomes complicated. In addition, when the movable IGV is additionally attached to the centrifugal compressor that has already been installed, the mechanism is complicated, so that the attachment becomes difficult.

  Furthermore, as shown in FIG. 12, the IGV drive shaft 52 is installed so as to be parallel to the main shaft 1, but the installation position of the IGV drive shaft 52 hinders the flow of refrigerant flowing in the inlet suction casing 4. Position. Therefore, the IGV drive shaft 52 becomes a resistance against the refrigerant flowing in the inlet suction casing 4.

  In view of such a problem, an object of the present invention is to provide a centrifugal compressor having a simple structure and capable of giving a swirling flow in the circumferential direction of a main shaft to an inflowing fluid.

  In order to achieve the above object, a centrifugal compressor of the present invention includes a main shaft that is rotationally driven, a plurality of impellers installed on an outer peripheral surface of the main shaft, a suction passage that supplies fluid to the impeller, An inlet suction casing including the suction flow path and having a ring-shaped space centered on the main shaft; and a suction port for supplying the fluid to the space of the inlet suction casing, In the centrifugal compressor in which the direction in which the fluid is supplied by the suction port is the radial direction of the main shaft, the suction port is provided and rotated to open and close the suction port, and the shaft is parallel to the main shaft. A butterfly valve type inlet guide vane, and the butterfly valve type inlet guide vane is in a fully closed state when its blade surface is perpendicular to the radial direction of the main shaft, and the blade surface is in the radial direction of the main shaft. It is characterized by being fully open when parallel To.

  In such a centrifugal compressor, the swirl flow is given to the fluid supplied to the inlet suction casing by rotating the inclination of the butterfly valve type inlet guide blade from the fully opened position in the direction opposite to the rotation direction of the main shaft. Can do.

  And the said butterfly valve type inlet guide wing | blade may be made into the shape which the surface shape corresponds with the cross-sectional shape of the said suction inlet, and there may be several butterfly valve type | mold inlet guide wing | blades, The butterfly valve-type inlet guide vanes are installed side by side in a direction perpendicular to both the radial direction and the axial direction of the main shaft, and the shape of the plurality of butterfly valve-type inlet guide vanes combined with the cross-sectional shape of the suction port The shape may be almost the same.

  Further, the butterfly valve type inlet guide vane may have a wing shape. Furthermore, the suction port may be configured by a cylinder having a columnar shape, or the suction port may be configured by a cylinder having a truncated cone shape.

  In addition, when the short pipe connected to the suction port is provided, the butterfly valve type inlet guide vane may be installed in the vicinity of the connection portion of the short pipe with the suction port. The valve-type inlet guide vane may be installed at the axial center position of the short pipe.

  According to the present invention, it is possible to give a swirling flow to the fluid to be supplied by providing the butterfly valve type inlet guide vane in the suction port so that the axis thereof is parallel to the main axis. Therefore, it is possible to simplify the installation process as compared with the conventional case where a plurality of IGVs are provided in the suction channel in the circumferential direction of the main shaft, and also to a centrifugal compressor that has already been installed. Can be added.

<First Embodiment>
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an axial cross-sectional view showing the configuration of the centrifugal compressor of the present embodiment. FIG. 2 is a cross-sectional view showing a surface perpendicular to the axial direction of the inlet suction casing of the centrifugal compressor of FIG. 1.

  A centrifugal compressor 10 in FIG. 1 supplies a fluid to a main shaft 1 that rotates by transmission of rotation from an electric motor (not shown), a plurality of impellers 2 arranged in a circumferential direction of the main shaft 1, and a fluid to the impeller 2. A suction flow path 3, a chamber-type inlet suction casing 4 including the suction flow path 3, a diffuser 5 that reduces the speed of the fluid compressed by the impeller 2 and converts kinetic energy into internal energy, and inlet suction A cylindrical short pipe 6 connected to the upper side of the casing 4 and a butterfly valve type IGV 7 installed in the vicinity of the connection portion between the inlet suction casing 4 and the short pipe 6 are provided.

  As shown in FIG. 2, the inlet suction casing 4 has a cylindrical shape extending in the axial direction of the main shaft 1, and includes a cylindrical portion 4 a serving as a suction port extending upward while a part of the upper portion is opened. At the tip of the cylindrical portion 4a, a ring-shaped inlet flange 4b extending to the outer peripheral side of the cylindrical portion 4a is provided. Moreover, as shown in FIG. 1, walls 4c and 4d constituted by surfaces perpendicular to the axial direction of the main shaft 1 are provided on the upstream side and the downstream side, respectively.

  And the protrusion part 4e protruded cylindrically from the wall 4c of the upstream side is comprised, By this protrusion part 4e, the outer periphery of the main axis | shaft 1 is covered upstream from the impeller 2. FIG. Further, the protrusion 4f protruding in a cylindrical shape from the downstream wall 4d is configured to cover the outer periphery of the protrusion 4e, so that the gap between the outer peripheral surface of the protrusion 4e and the inner peripheral surface of the protrusion 4f is increased. In addition, the suction flow path 3 is formed. On the downstream side of the wall 4d on which the protrusion 4f is formed, a flow path for flowing the fluid flowing through the suction flow path 3 is configured in the casing 40 including the inlet suction casing 4 as a part. An impeller 2 is installed on a flow path formed in the casing, and a diffuser 5 is formed.

  In the centrifugal compressor 10 having the configuration shown in FIGS. 1 and 2, the butterfly valve type IGV 7 is installed in the vicinity of the connecting portion with the cylindrical portion 4 a in the short tube 6. That is, as shown in FIG. 2, the short pipe 6 is provided with a ring-shaped flange 6a for connecting to the inlet flange 4b of the cylindrical portion 4a, and the drive shaft 7a of the butterfly valve type IGV 7 is directly above the flange 6a. The axial direction is set to be parallel to the axial direction of the main shaft 1. A butterfly valve type IGV 7 is constituted by a circular blade 7b having the same shape as the inner wall surface of the short tube 6 with the drive shaft 7a as a center. That is, the butterfly valve type IGV 7 has a configuration in which the drive shaft 7a is penetrated at a diameter position parallel to the axial direction of the main shaft 1 with respect to the circular blade 7b.

  As shown in FIG. 2, the butterfly valve type IGV 7 configured as described above is caused to flow into the inlet suction casing 4 through the short pipe 6 by causing the blade 7 b to rotate on a circle centering on the drive shaft 7 a. The fluid flow rate is set. That is, as shown in FIG. 3, when the surface of the blade 7 b is a surface perpendicular to the radial direction of the main shaft 1, the entire outer peripheral surface of the blade 7 b comes into contact with the inner wall surface of the short tube 6, and is in a fully closed state. . Conversely, as shown in FIG. 4, when the surface of the blade 7 b is a surface parallel to the radial direction of the main shaft 1, only the drive shaft 7 a portion of the blade 7 b comes into contact with the inner wall surface of the short tube 6, and the fully opened state. It becomes. Therefore, the flow rate of the fluid can be controlled between the fully closed state of FIG. 3 and the fully open state of FIG. 4 by rotating the blade 7b by the drive shaft 7a and changing the angle of the blade 7b.

  When the main shaft 1 is driven counterclockwise and the fluid is compressed by the impeller 2, the blade 7b of the butterfly valve type IGV7 is rotated counterclockwise by the drive shaft 7a as shown in FIG. The angle is tilted between the fully closed state of FIG. 3 and the fully open state of FIG. By tilting the blade 7b in this way, a flow along the direction in which the blade 7b of the butterfly valve type IGV 7 is tilted can be given to the fluid flowing in from above the short tube 6. That is, in the vicinity of the connection portion between the inlet suction casing 4 and the flange 4b, a swirling flow can be generated with respect to the fluid flow on the left and right of the straight line X connecting the main shaft 1 and the drive shaft 7a.

  Then, a flow along the inclined direction of the blade 7b of the butterfly valve type IGV 7 is given, and a fluid having non-uniformity in the left and right flow of the straight line X flows into the inlet suction casing 4 from the inlet flange 4b. . Therefore, a fluid flows into the inlet suction casing 4 through the cylindrical portion 4 a, and this fluid is given a flow in a counterclockwise direction with respect to the circumferential direction around the main shaft 1. Thereby, it flows so as to rotate in the counterclockwise direction along the inner wall of the inlet suction casing 4 to generate a swirling flow, and the suction flow path 3 in the inlet suction casing 4 has a fluid having swirling flow. Will be supplied.

  Thus, according to this embodiment, instead of providing a plurality of movable IGVs for the suction flow path 3 as in the prior art, the butterfly valve type IGV 7 is provided on the upstream side of the inlet suction casing 4, thereby A swirling flow can be easily given to the fluid flowing into the passage 3. That is, since the swirl flow can be given to the fluid by a simple structure compared with the conventional structure, not only can the production be simplified, but also an already installed centrifugal compressor can be easily additionally installed. Can do.

  The blade 7b of the butterfly valve type IGV7 may have a plate shape having substantially the same thickness as shown in FIG. 5 (a), and the upstream thickness as shown in FIG. 5 (b). It is also possible to use a wing shape formed so as to be thick. When the blade 7b has a blade shape as shown in FIG. 5 (b), the upstream front end side is thick and the downstream rear end is thin.

  In the present embodiment, the drive shaft 7a of the butterfly valve type IGV7 is installed in the vicinity of the connection position with the inlet suction casing 4 of the short pipe 6 as shown in FIG. As described above, the butterfly valve type IGV 7 may be installed so that the drive shaft 7 a is arranged at the center position of the short tube 6. Thus, the butterfly valve type IGV 7 can be housed in the short tube 6 by arranging the drive shaft 7 a at the center position of the short tube 6. Then, the butterfly valve type IGV 7 can be added only by connecting the short pipe 6 provided with the butterfly valve type IGV 7 to the inlet suction casing 4.

  On the other hand, as shown in FIG. 2, when the drive shaft 7 a is installed near the connection position with the inlet suction casing 4 of the short pipe 6, the butterfly valve type IGV 7 is installed near the inlet suction casing 4. Therefore, a swirl flow with little attenuation can be introduced.

  Furthermore, in this embodiment, as shown in FIG. 2, the inlet suction casing 4 has a columnar cylindrical portion 4a where the short pipe 6 is connected. Instead of this cylindrical portion 4a, FIG. As shown, it may be a circular truncated cone part 41a. That is, the cylindrical portion 41 a is configured such that the cross section becomes narrower toward the inlet flange 4 b installed at the tip, while the cross section becomes wider toward the main shaft 1. By comprising in this way, the flow of the fluid set by butterfly valve type IGV7 can be maintained and made to flow in the direction swirled by the inlet suction casing 4. FIG.

<Second Embodiment>
A second embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a cross-sectional view that is a plane perpendicular to the axial direction of the inlet suction casing of the centrifugal compressor of the present embodiment. In addition, in the centrifugal compressor of this embodiment, about the part used for the same purpose as the centrifugal compressor of 1st Embodiment, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  The centrifugal compressor 10a of this embodiment is a butterfly valve type IGV71 having a shape obtained by dividing the butterfly valve type IGV7 into three parts as shown in FIG. 8 instead of the butterfly valve type IGV7 in the centrifugal compressor 10 of the first embodiment. ˜73 are provided in the short tube 6. That is, the three drive shafts 71a to 71c parallel to the main shaft 1 are perpendicular to the axial direction of the main shaft 1 and the short tube 6 at the same height position directly above the flange 6a of the short tube 6. Installed at the same interval.

  The butterfly valve type IGV 71 is configured by installing the drive shaft 71a at the center position of the blade 71b, and the butterfly valve type IGV 72 is configured by installing the drive shaft 72a at the center position of the blade 72b. A butterfly valve type IGV 73 is configured by installing 73a at the center position of the wing 73b. That is, as shown in FIG. 9, the blades 71b to 73b have a shape in which the circular blade 7a is divided into three in a direction perpendicular to the drive shafts 71a to 73a, and the blades 71b and 73b are divided into three ends. And the wing 72b is a wing on the center side divided into three. FIG. 9 is a view when the blades 71b to 73b are horizontal surfaces and the butterfly valve IGVs 71 to 73 are fully closed in the short pipe 6, and the ends of the blades 71b to 73b are in contact with each other. It becomes.

  In the blades 71b and 73b, the length parallel to the drive shafts 71a and 71c is the length of the position where the drive shafts 71a and 71c are installed at any position in the direction perpendicular to the drive shafts 71a and 71c. The length is as follows. That is, as shown in the configuration when fully closed in FIG. 9, the length of the blades 71b and 73b parallel to the drive shafts 71a and 71c is determined from the central position in the direction perpendicular to the drive shafts 71a and 71c. In the portion up to the edge position adjacent to 72b, the length of the position at the center in the direction perpendicular to the drive shafts 71a and 71c is constant.

  When each of the butterfly valve type IGVs 71 to 73 is fully opened, each of the blades 71b to 73b is a surface parallel to the radial direction of the main shaft 1, as shown in FIG. At this time, since the blades 71b to 73b have a shape in which the blade 7b is divided into three at equal intervals, the axial length of the short tube 6 is shorter than that of the blade 7b. Further, the space inside the short tube 6 is divided into four by the blades 71b to 73b at the positions of the drive shafts 71a to 73b.

  In such a configuration, when the main shaft 1 is driven counterclockwise and the fluid is compressed by the impeller 2, in the butterfly valve type IGVs 71 to 73, the blades 71b to 73b are driven by the drive shafts 71a to 73a. It is rotated counterclockwise and tilted to an angle between the fully closed state of FIG. 9 and the fully open state of FIG. Thereby, while dividing the flow of the fluid which flows in from the upper direction of the short tube 6, the flow along the direction in which the blades 71b to 73b of the butterfly valve type IGVs 71 to 73 are inclined can be given.

  And the fluid to which the flow along the direction in which the wing | blade 71b-73b of butterfly valve type IGV71-73 inclined was given flows in in the inlet suction casing 4 from the inlet flange 4b. Therefore, a fluid flows into the inlet suction casing 4 through the cylindrical portion 4 a, and this fluid is given a flow in a counterclockwise direction with respect to the circumferential direction around the main shaft 1. Thereby, it flows so as to rotate in the counterclockwise direction along the inner wall of the inlet suction casing 4 to generate a swirling flow, and the suction flow path 3 in the inlet suction casing 4 has a fluid having swirling flow. Will be supplied. At this time, since the flow of the fluid flowing into the inlet suction casing 4 is divided by the blades 71b to 73b, the generation of the swirling flow in the inlet suction casing 4 is promoted.

  In this embodiment as well, as in the first embodiment, the blades 71b to 73b of the butterfly valve type IGVs 71 to 73 may have a plate shape whose thickness is substantially the same as shown in FIG. Alternatively, as shown in FIG. 11 (b), a wing shape may be formed so that the upstream thickness is increased. Further, the butterfly valve type IGVs 71 to 73 may be installed so that the drive shafts 71 a to 73 a are arranged at the center position of the short pipe 6. Furthermore, the cylindrical portion of the inlet suction casing 4 may have a truncated cone shape.

  The present invention is applicable to a centrifugal compressor that compresses a fluid. Moreover, in order to use the compressed fluid, it can be applied to a turbo refrigerator or various chemical / gas plants in which a centrifugal compressor is installed.

These are sectional drawings of the axial direction which shows the structure of the centrifugal compressor of 1st Embodiment. These are sectional drawings used as the surface perpendicular | vertical to the axial direction in the inlet_port | entrance suction casing of the centrifugal compressor of FIG. These are figures which show a structure when the butterfly valve type IGV of the centrifugal compressor of FIG. 1 is made into a full closure. These are figures which show a structure when the butterfly valve type IGV of the centrifugal compressor of FIG. 1 is fully opened. These are figures which show the structure of the blade | wing of the butterfly valve type IGV of the centrifugal compressor of FIG. These are figures which show the example of a structure when the installation position of butterfly valve type IGV is changed. These are figures which show the example of a structure when an inlet_port | entrance suction casing is made into another shape. These are sectional drawings used as the surface perpendicular | vertical to the axial direction in the inlet_port | entrance suction casing of the centrifugal compressor of 2nd Embodiment. These are figures which show a structure when the butterfly valve type IGV of the centrifugal compressor of FIG. These are figures which show a structure when the butterfly valve type IGV of the centrifugal compressor of FIG. 8 is fully opened. These are figures which show the structure of the blade | wing of the butterfly valve type IGV of the centrifugal compressor of FIG. These are sectional drawings of the axial direction which show the structure of the conventional centrifugal compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main shaft 2 Impeller 3 Suction flow path 4 Inlet suction casing 5 Diffuser 6 Short pipe 10, 10a Centrifugal compressor 7 Butterfly valve type IGV

Claims (8)

A main shaft that is driven to rotate, a plurality of impellers installed on the outer peripheral surface of the main shaft, a suction passage that supplies fluid to the impeller, and a wheel that includes the suction passage and that is centered on the main shaft An inlet suction casing having a shaped space; and a suction port for supplying the fluid to the space of the inlet suction casing, wherein the suction port supplies the fluid in a radial direction of the main shaft. In a centrifugal compressor,
The suction port is provided with a butterfly valve type inlet guide vane that rotates to open and close the suction port, and whose axis is parallel to the main shaft,
The butterfly valve-type inlet guide blade is fully closed when its blade surface is perpendicular to the radial direction of the main shaft, and is fully open when its blade surface is parallel to the radial direction of the main shaft. A centrifugal compressor characterized by that.   2. The centrifugal compressor according to claim 1, wherein the butterfly valve-type inlet guide vane has one, and a surface shape thereof coincides with a cross-sectional shape of the suction port.   There are a plurality of the butterfly valve type inlet guide vanes, and the plurality of butterfly valve type inlet guide vanes are arranged side by side in a direction perpendicular to both the radial direction and the axial direction of the main shaft, and the plurality of butterfly valve type inlet guide vanes 2. The centrifugal compressor according to claim 1, wherein a shape obtained by combining the surfaces is substantially the same as a cross-sectional shape of the suction port.   The centrifugal compressor according to any one of claims 1 to 3, wherein the butterfly valve-type inlet guide blade has a blade shape.   The centrifugal compressor according to any one of claims 1 to 4, wherein the suction port is configured by a cylinder having a columnar shape.   The centrifugal compressor according to any one of claims 1 to 4, wherein the suction port is configured by a cylinder having a truncated cone shape. Comprising a short pipe connected to the inlet;
The centrifugal compressor according to any one of claims 1 to 6, wherein the butterfly valve-type inlet guide vane is installed in the vicinity of a connection portion between the short pipe and the suction port. Comprising a short pipe connected to the inlet;
The centrifugal compressor according to any one of claims 1 to 6, wherein the butterfly valve-type inlet guide vane is installed at a central position in an axial direction of the short pipe.

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