JP6237077B2 - Centrifugal compressor - Google Patents

Description

  The present invention relates to a centrifugal compressor such as an industrial centrifugal compressor or a gas turbine centrifugal compressor that compresses a gas such as air using centrifugal force.

  In recent years, with the demand for higher pressure ratios of centrifugal compressors, the development of centrifugal compressors has become active, and the applicant of this application has also filed a centrifugal compressor that can achieve higher pressure ratios, Published (see Patent Document 1). And the structure of the centrifugal compressor which concerns on the prior art is as follows.

  The centrifugal compressor according to the prior art includes a housing, and the housing has a shroud (accommodating wall) inside. An impeller is rotatably provided in the shroud of the housing. The impeller includes a disk whose hub surface (outer peripheral surface) extends radially outward from one side in the axial direction of the impeller. . Furthermore, a plurality of blades, which are components of the impeller, are integrally provided on the disk hub surface at intervals in the circumferential direction, and the leading edge of each blade extends along the shroud of the housing. Yes. Here, each blade is configured such that the blade thickness center line of the trailing edge is inclined toward the rotation direction side of the impeller with respect to the radial direction of the impeller.

  An annular treatment cavity is formed inside the housing, and an extraction opening for extracting air is formed on the downstream side of the front edge of the blade in the shroud of the housing so as to communicate with the treatment cavity. Has been. In addition, an outflow opening for allowing gas to flow out to the inlet side of the impeller is formed in communication with the treatment cavity on the upstream side of the front edge of the blade in the shroud of the housing. And in the outflow opening part of a housing, the several fin is provided in the circumferential direction at intervals, and each fin is comprised so that it may incline to the opposite side of the said rotation direction with respect to the said radial direction. Has been.

  With the above-described configuration, the operation of the centrifugal compressor is started, and the impeller is rotated to compress the gas sucked into the housing using centrifugal force. The compressed gas is discharged to the outside of the housing.

  When the flow rate (actual flow rate) of the gas sucked into the housing is reduced during the operation of the centrifugal compressor, a part of the gas flowing into the impeller side is extracted by the extraction opening and flows into the treatment cavity. The gas flowing into the treatment cavity flows from the extraction opening side to the outflow opening side, and flows out from the outflow opening to the impeller inlet side. Thereby, a part of the gas flowing into the impeller side is circulated between the outflow opening and the extraction opening, so that the apparent flow rate of the gas flowing into the impeller side can be made larger than the actual flow rate.

  Further, since each blade is configured such that the blade thickness center line of the trailing edge is inclined toward the rotational direction with respect to the radial direction, the outer diameter of the impeller is reduced to increase the peripheral speed of the impeller. It is possible to sufficiently secure a heat insulating head (corresponding to the work amount of the impeller) in the vicinity of the design point (including the design point) while suppressing. As a result, it is possible to increase the pressure ratio of the centrifugal compressor while suppressing an increase in friction loss between the rear surface of the shroud of the housing or the impeller and the gas and an increase in the temperature of the impeller due to the friction with the gas.

  Since each fin is inclined to the opposite side of the rotational direction with respect to the radial direction, the flow on the inlet side of the impeller is swirled in the direction opposite to the rotational direction (swirl flow), and surge The deterioration of the heat insulating head in the vicinity can be sufficiently suppressed. Thereby, the operating range on the low flow rate side of the centrifugal compressor can be sufficiently ensured.

JP2013-40587A

  By the way, as described above, while ensuring a sufficient operating range on the low flow rate side of the centrifugal compressor, it is possible to increase the pressure ratio of the centrifugal compressor while suppressing an increase in friction loss between the housing shroud and the gas. In order to achieve this, a plurality of fins are required to impart a swirl in the direction opposite to the rotational direction to the flow on the inlet side of the impeller. Therefore, the number of parts of the centrifugal compressor increases, leading to a complicated configuration of the centrifugal compressor and an increase in manufacturing cost.

  In other words, while ensuring a sufficient operating range on the low flow rate side of the centrifugal compressor, while suppressing an increase in friction loss between the shroud of the housing and the gas and the like, the high pressure ratio of the centrifugal compressor, simplification of the configuration, In addition, there is a problem that it is not easy to reduce the manufacturing cost.

  Then, an object of this invention is to provide the centrifugal compressor of a novel structure which can solve the above-mentioned problem.

According to an aspect of the present invention, in a centrifugal compressor that compresses gas using centrifugal force, a housing having a shroud (accommodating wall) inside, a hub surface (outer peripheral surface) that is rotatably provided in the housing. disc but extending radially outwardly from one axial side, and one side in the axial direction as the circumferential direction spaced apart and leading edge to the hub surface of the disk along the shroud of the housing anda impeller having a plurality of blades extending radially outward from, the blade thickness center line is the impeller Atsushi Hane center line and the shroud side of the hub side of the trailing edge of each blade (tip side) configured for radial so as to be inclined in opposite directions to each other, in other words, one of the hub side of the Atsushi Hane center line and the shroud side of the Atsushi Hane center line of the trailing edge of each blade The other Atsushi Hane center of the Atsushi Hane center line is inclined to the rotational direction side with respect to the radial direction, and the hub side of the Atsushi Hane center line and the shroud side of the Atsushi Hane center line of the trailing edge of each blade Ru der that the line is configured so as to be inclined to the opposite side of the rotation direction with respect to the radial direction.

  In the description of the specification and claims of the present application, “gas” means air, nitrogen gas, hydrogen gas, and the like. Further, “provided” means not only directly provided but also indirectly provided via another member, and “provided integrally” It is meant to include being formed.

According to the aspect of the present invention, the operation of the centrifugal compressor is started, and the impeller is rotated to compress the gas sucked into the housing using centrifugal force. The compressed gas is discharged to the outside of the housing.

  In addition to the above-described operation, the one blade thickness center line at the trailing edge of each blade is configured to be inclined toward the rotational direction with respect to the radial direction, so that the outer diameter of the impeller is reduced. Thus, while suppressing the increase in the peripheral speed of the impeller, the thermal insulation head (corresponding to the work amount of the impeller) in the vicinity of the design point (including the design point) is sufficiently provided on either the hub side or the shroud side of each blade. Can be secured.

  The other blade thickness center line at the trailing edge of each blade is configured to incline to the opposite side of the rotational direction with respect to the radial direction, so that the flow on the inlet side of the impeller is opposite to the rotational direction. Even without using a plurality of fins that provide direction swirling, it is possible to sufficiently secure a heat insulating head in the vicinity of the surge on either the shroud side or the hub side of each blade.

  According to the present invention, the outer diameter of the impeller is reduced to suppress the increase in the peripheral speed of the impeller, and a sufficient heat insulation head is secured near the design point on either the hub side or the shroud side of each blade. Therefore, it is possible to increase the pressure ratio of the centrifugal compressor while suppressing an increase in friction loss between the rear surface of the shroud or the impeller of the housing and the gas and an increase in the temperature of the impeller due to the friction with the gas. . Further, since a heat insulating head in the vicinity of the surge can be sufficiently secured on either the shroud side or the hub side of each blade without using a plurality of the fins, the operating range on the low flow side of the centrifugal compressor is sufficient. In addition, the number of parts of the centrifugal compressor can be reduced, and the configuration of the centrifugal compressor can be simplified and the manufacturing cost can be reduced.

  In other words, according to the present invention, the centrifugal compressor is provided with a sufficient operating range on the low flow rate side of the centrifugal compressor, and while suppressing an increase in friction loss between the shroud and the like of the housing and gas. The pressure ratio can be increased, the configuration can be simplified, and the manufacturing cost can be reduced.

FIG. 1 is a front view of an impeller in a centrifugal compressor according to an embodiment of the present invention. FIG. 2 is a perspective view of the impeller in the centrifugal compressor according to the embodiment of the present invention. FIG. 3 is a schematic sectional side view of the centrifugal compressor according to the embodiment of the present invention. FIG. 4A is a view showing a speed triangle of a blade outlet on the hub side in the centrifugal compressor according to the embodiment of the present invention, and FIG. 4B is a shroud side in the centrifugal compressor according to the embodiment of the present invention. It is a figure which shows the speed triangle of the blade exit of.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 4A and 4B. In the drawings, “F” indicates the forward direction, and “R” indicates the backward direction.

  As shown in FIGS. 1 to 3, a centrifugal compressor 1 according to an embodiment of the present invention is used in a gas turbine, an industrial air facility, or the like, and compresses air (an example of gas) A using centrifugal force. To do. And the specific structure of the centrifugal compressor 1 which concerns on embodiment of this invention is as follows.

  The centrifugal compressor 1 according to the embodiment of the present invention includes a housing 3, and the housing 3 has a housing body 5 having a shroud (accommodating wall) 5 s inside, and a rear side of the housing body 5. And a provided seal plate 7. The seal plate 7 is integrally connected to another housing (not shown) in a gas turbine or industrial air equipment.

  An impeller 9 is provided in the housing body 5 so as to be rotatable around an axis 9c thereof. The impeller 9 is integrated with a rotor shaft 11 provided rotatably in another housing via a fixing nut 13. Connected. Further, the impeller 9 includes a disk 15, and a hub surface 15h of the disk 15 extends from the axial direction (axial direction of the impeller 9) AD one side (front side) to the radial direction (radial direction of the impeller 9) RD. The rear surface 15 b of the disk 15 faces the seal plate 7. Further, a plurality of blades (blades) 17 which are constituent members of the impeller 9 are provided on the hub surface 15h of the disk 15 at intervals in the circumferential direction. Extending along the shroud 5s. Here, the axial length of each blade 17, specifically, the axial direction AD of the impeller 9 from the shroud side end (tip side end) 17 fs of the front edge 17 f of each blade 17 to the hub side end 17 rh of the rear edge 17 r. The length is set to the same length. Instead of using the blades 17 having the same axial length, a plurality of types of blades (not shown) having different axial lengths may be used.

  A suction port 19 for sucking air A into the housing 3 is formed on the inlet side of the impeller 9 in the housing body 5 (upstream side when viewed from the flow direction of the main flow of air A). An annular diffuser passage 21 that decelerates and pressurizes the compressed air A is formed at the outlet side of the impeller 9 in the housing body 5 (downstream side when viewed from the flow direction of the main flow of the air A). . Further, a discharge port (not shown) for discharging the compressed air A from the inside of the housing 3 is formed at an appropriate position of the housing body 5, and this discharge port communicates with the diffuser flow path 21. .

  Then, the principal part of the centrifugal compressor 1 which concerns on embodiment of this invention is demonstrated.

  As shown in FIGS. 1 and 4 (a) and 4 (b), each blade 17 has a blade thickness center line 17c on the hub side (base end side) and a blade thickness center line on the shroud side (tip side) at the rear edge 17r. 17c is comprised so that it may incline in the mutually opposite direction with respect to radial direction RD. Here, the hub side of the rear edge 17r refers to a portion of the rear edge 17r located on the hub surface 15h side of the disk 15, and the shroud side of the rear edge 17r refers to the housing body 5 of the rear edge 17r. It refers to a portion of the (housing 3) located on the shroud 5s side.

  Specifically, each blade 17 is configured such that the hub-side blade thickness center line 17c at the trailing edge 17r is inclined in the rotational direction (rotational direction of the impeller 9) SD with respect to the radial direction RD. The sign of the hub outlet blade angle βh in each blade 17 is positive. Each blade 17 is configured such that the blade thickness center line 17c on the shroud side at the trailing edge 17r is inclined to the opposite side of the rotational direction SD with respect to the radial direction RD. The sign of the outlet blade angle βs is negative. Here, the outlet blade angle βh on the hub side in the blade 17 refers to an angle formed between the radial direction RD and the blade-side blade thickness center line 17c on the rear edge 17r of the blade 17. The shroud-side outlet blade angle βs of the blade 17 refers to an angle formed by the radial direction RD and the shroud-side blade thickness center line 17c of the blade 17 at the trailing edge 17r.

  Instead of each blade 17 being configured as described above, the hub-side blade thickness center line 17c at the trailing edge 17r is inclined in the direction opposite to the rotational direction SD with respect to the radial direction RD and at the trailing edge 17r. The shroud side blade thickness center line 17c may be configured to incline toward the rotational direction SD with respect to the radial direction RD.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

(i) Normal action By starting the operation of the centrifugal compressor 1 and rotating the impeller 9 integrally by the rotation of the rotor shaft 11, the air A sucked into the housing 3 through the suction port 19 is obtained. Compress using centrifugal force. The compressed air A is pressurized by the diffuser flow path 21 and is discharged to the outside of the housing 3 through the discharge port.

(ii) Unique Action There is a heat insulating head H that correlates with the pressure ratio of the centrifugal compressor 1, and the pressure ratio of the centrifugal compressor 1 increases as the heat insulating head H increases. And the heat insulation head H is shown by following Formula.

H = η (U ₂ Cu ₂ −U ₁ Cu ₁ ) G Equation (1)
η: Compressor efficiency U ₂ : Blade outlet peripheral speed (impeller outlet peripheral speed)
Cu ₂ : Blade outlet absolute speed (impeller outlet absolute speed) circumferential component U ₁ : Blade inlet peripheral speed (impeller outlet peripheral speed)
Cu ₁ : circumferential component of blade inlet absolute velocity (impeller inlet absolute velocity) G: air flow rate When there is no swirling flow at the inlet of impeller 9, circumferential component Cu ₁ of blade inlet absolute velocity may be ignored The equation (1) can be replaced with the following equation.

H = ηU ₂ Cu ₂ G Equation (2)
Here, in FIGS. 4A and 4B, U ₂ indicated by a solid line arrow is the blade outlet peripheral speed (impeller outlet peripheral speed) on the large flow rate side (near the design point), and U ₂ indicated by the dotted line arrow is small. Blade peripheral speed on the flow rate side (near surge). V ₂ indicated by a solid line arrow is a blade outlet relative speed (impeller outlet relative speed) on the large flow rate side, and V ₂ indicated by a dotted line arrow is a blade outlet relative speed on the small flow side. Further, C ₂ indicated by the solid line arrow is the blade outlet absolute speed on the large flow rate side (impeller outlet absolute speed), C ₂ indicated by the dotted line arrow is the blade outlet absolute speed on the small flow rate side, and Cu ₂ indicated by the solid line arrow is: The circumferential component of the blade outlet absolute velocity on the large flow rate side, Cu ₂ indicated by the dotted arrow is the circumferential component of the blade outlet absolute velocity on the small flow rate side.

Since the blade thickness center line 17c on the hub side at the rear edge 17r of each blade 17 is configured to incline toward the rotational direction SD with respect to the radial direction RD, the above-described equation (2) of the heat insulating head H is applied. Then, while reducing the outer diameter of the impeller 9 and suppressing the increase in the peripheral speed of the impeller 9, on the hub side of each blade 17, the circumferential component Cu ₂ of the blade outlet absolute speed on the large flow rate side is increased, A heat insulating head (corresponding to the work amount of the impeller 9) in the vicinity of the design point (including the design point) can be sufficiently secured.

Since the blade thickness center line 17c on the shroud side at the trailing edge 17r of each blade 17 is configured to incline to the opposite side of the rotation direction SD with respect to the radial direction RD, the flow on the inlet side of the impeller 9 rotates Even if not using a plurality of fins that give a swirl in the opposite direction to SD, applying the above formula (2) of the heat insulation head H, the circumferential direction of the blade outlet absolute speed on the small flow rate side on the shroud side of each blade 17 By increasing the component Cu ₂ , it is possible to sufficiently secure the heat insulating head in the vicinity of the surge. Similarly, when the above-described equation (2) of the heat insulating head H is applied, the blade thickness center line 17c on the shroud side at the trailing edge 17r of each blade 17 is inclined toward the rotational direction SD with respect to the radial direction RD. Compared to the case, the heat insulating head H on the shroud side of each blade 17 can be made smaller, and the pressure difference between the pressure surface and the suction surface on the shroud side of each blade 17 can be reduced.

  Therefore, according to the embodiment of the present invention, the outer diameter of the impeller 9 can be reduced to suppress the increase in the peripheral speed of the impeller 9, and a sufficient heat insulating head near the design point can be secured on the hub side of each blade 17. Therefore, it is possible to increase the pressure ratio of the centrifugal compressor 1 while suppressing an increase in friction loss between the back surface of the shroud 5s of the housing body 5 or the impeller 9 and air and an increase in temperature of the impeller 9 due to friction with air. . Moreover, since a heat insulating head in the vicinity of the surge can be sufficiently secured on the shroud side of each blade 17 without using a plurality of fins, centrifugal compression is performed while sufficiently securing the operating range on the low flow rate side of the centrifugal compressor 1. The number of parts of the machine 1 can be reduced, and the configuration of the centrifugal compressor 1 can be simplified and the manufacturing cost can be reduced. Further, since the heat insulating head H on the shroud side of each blade 17 can be reduced to reduce the pressure difference between the pressure surface and the suction surface on the shroud side of each blade 17, the clearance flowing from the pressure surface side to the suction surface side of the blade 17. The flow can be reduced and the compressor efficiency of the centrifugal compressor 1 can be improved.

  That is, according to the embodiment of the present invention, while ensuring a sufficient operating range on the low flow rate side of the centrifugal compressor 1, while suppressing an increase in friction loss between the shroud 5s of the housing body 5 and the air and the like, It is possible to increase the pressure ratio of the centrifugal compressor 1, simplify the configuration, reduce the manufacturing cost, and improve the compressor efficiency.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, It can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

  1: centrifugal compressor, 3: housing, 5: housing body, 5s: shroud, 7: seal plate, 9: impeller, 9c: shaft center, 11: rotor shaft, 13: fixing nut, 15: disk, 15b: rear surface 15h: hub surface, 17: blade, 17c: blade thickness center line, 17f: front edge, 17fs: shroud side end of front edge, 17r: rear edge, 17rh: hub side end of rear edge, 17t: tip edge, 19: suction port, 21: diffuser flow path, βs: outlet blade angle on the shroud side of the blade, βh: outlet blade angle on the hub side of the blade

Claims (2)

In a centrifugal compressor that compresses gas using centrifugal force,
A housing having a shroud inside;
Rotatably disposed within the housing, and the tip edge said housing spaced hub surface disk extending radially outwardly from one axial side, and the intervals in the circumferential direction on the hub surface of the disk An impeller having a plurality of blades extending radially outward from one side in the axial direction along the shroud of
Atsushi Hane center line of the Atsushi Hane center line and the shroud side of the hub side of the trailing edge of each blade is configured so as to be inclined in opposite directions with respect to the radial direction of the impeller, the centrifugal compressor. Opposite direction of the rotational direction Atsushi Hane center line of the rotational direction to the inclined only One shroud side of the impeller hub side of the Atsushi Hane center line with respect to the radial direction of the trailing edge of each blade with respect to the radial direction It is configured to tilt to the side, a centrifugal compressor according to claim 1.

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