WO2022180902A1 - 多段遠心圧縮機 - Google Patents
多段遠心圧縮機 Download PDFInfo
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- WO2022180902A1 WO2022180902A1 PCT/JP2021/034635 JP2021034635W WO2022180902A1 WO 2022180902 A1 WO2022180902 A1 WO 2022180902A1 JP 2021034635 W JP2021034635 W JP 2021034635W WO 2022180902 A1 WO2022180902 A1 WO 2022180902A1
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- centrifugal compressor
- stage
- return
- blade
- downstream
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- 239000012530 fluid Substances 0.000 claims description 43
- 238000011144 upstream manufacturing Methods 0.000 claims description 23
- 230000007423 decrease Effects 0.000 claims description 13
- 230000003068 static effect Effects 0.000 abstract description 5
- 238000000926 separation method Methods 0.000 description 15
- 238000010586 diagram Methods 0.000 description 11
- 239000007789 gas Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 230000001133 acceleration Effects 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 239000011295 pitch Substances 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 235000014121 butter Nutrition 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/26—Rotors specially for elastic fluids
- F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
- F04D29/284—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps for compressors
- F04D29/286—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps for compressors multi-stage rotors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
- F04D17/08—Centrifugal pumps
- F04D17/10—Centrifugal pumps for compressing or evacuating
- F04D17/12—Multi-stage pumps
- F04D17/122—Multi-stage pumps the individual rotor discs being, one for each stage, on a common shaft and axially spaced, e.g. conventional centrifugal multi- stage compressors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
- F04D17/08—Centrifugal pumps
- F04D17/10—Centrifugal pumps for compressing or evacuating
- F04D17/12—Multi-stage pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
- F04D29/44—Fluid-guiding means, e.g. diffusers
- F04D29/441—Fluid-guiding means, e.g. diffusers especially adapted for elastic fluid pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/40—Casings; Connections of working fluid
- F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
- F04D29/44—Fluid-guiding means, e.g. diffusers
- F04D29/441—Fluid-guiding means, e.g. diffusers especially adapted for elastic fluid pumps
- F04D29/444—Bladed diffusers
Definitions
- Patent Document 1 in order to obtain a centrifugal turbomachine having return blades of a shape that can suppress a decrease in efficiency when downsized, a centrifugal turbomachine configured to flow from a diffuser into a return passage via a turning portion is disclosed.
- the return blades provided in the return passage are arranged in multiple circular cascades, and the blade angle of the return blades (outer blades arranged on the most upstream side) at the inlet of the return passage is axial (high Centrifugal turbomachines configured differently in the longitudinal direction) are described.
- An object of the present invention is to provide a multi-stage centrifugal compressor that can maintain and improve efficiency while reducing the outer diameter of the stationary flow path.
- the multistage centrifugal compressor of the present invention is configured as described in the claims.
- a specific example of the multistage centrifugal compressor in the present invention includes a rotating shaft and a plurality of centrifugal impellers attached to the rotating shaft, and one of the plurality of centrifugal impellers and the one centrifugal impeller a diffuser in which the outflowing fluid flows in a centrifugal direction away from the rotating shaft; and a diffuser provided downstream of the diffuser. a return channel for flowing in a return direction; and a turning portion for turning the flow of the fluid that has flowed through the diffuser from the centrifugal direction to the axial direction of the rotating shaft and further turning from the axial direction to the returning direction.
- the centrifugal compressor stage is a multi-stage centrifugal compressor in which a plurality of stages are arranged in series in the direction of the rotation shaft, and the return flow path is a plurality of stages arranged in a circular blade cascade around the center line of the rotation shaft.
- a return vane is provided, and a plurality of the return vanes are installed as a front blade and a rear blade from the upstream side to the downstream side of the flow of the fluid in the return passage, and the suction surface of the rear blade is provided with the above-described return vane.
- the trailing wing is circumferentially offset on the pressure surface side of the leading wing so as to guide the flow on the pressure surface side of the leading wing.
- At least one of the circumferential angles ⁇ formed in the circumferential direction is changed according to the centrifugal compressor stage position of the multi-stage centrifugal compressor.
- FIG. 1 is a meridional cross-sectional view showing the upper half of an example of the overall configuration of a multistage centrifugal compressor to which the present invention is applied;
- FIG. 2 is a partially enlarged cross-sectional view of the multistage centrifugal compressor shown in FIG. 1;
- FIG. 3 is a diagram showing half of a state in which the vicinity of the return vanes shown in FIGS. 1 and 2 is viewed from the downstream side in the axial direction of the rotating shaft; It is a figure which shows the half of the state which looked at the periphery of the return vane in the Example of this invention from the downstream of the axial direction of the rotating shaft.
- FIG. 1 is a meridional cross-sectional view showing the upper half of an example of the overall configuration of a multistage centrifugal compressor to which the present invention is applied
- FIG. 2 is a partially enlarged cross-sectional view of the multistage centrifugal compressor shown in FIG. 1
- FIG. 3 is a diagram showing half of
- FIG. 4 is a schematic diagram showing the positional relationship between the leading blade and the trailing blade of the return vane in the embodiment of the present invention
- FIG. 5 is a diagram showing the shape characteristics of the leading blade of the first stage return vane in the embodiment of the present invention
- FIG. 5 is a diagram showing the shape characteristics of the front blades of the return vanes in the intermediate stage located between the first stage and the final stage in the embodiment of the present invention
- FIG. 4 is a diagram showing the shape characteristics of the front blade of the final stage return vane in the embodiment of the present invention
- FIG. 5 is a diagram showing the shape characteristics of the leading blade of the first stage return vane in the embodiment of the present invention
- FIG. 5 is a diagram showing the shape characteristics of the front blades of the return vanes in the intermediate stage located between the first stage and the final stage in the embodiment of the present invention
- FIG. 4 is a diagram showing the shape characteristics of the front blade of the final stage return vane in the embodiment of the present invention
- FIG. 4 is a diagram showing velocity triangles near the entrance of the front wing of the fluid entering the front wing of the return vane in the embodiment of the present invention;
- FIG. 4 is a diagram showing features;
- FIG. 4 is a diagram showing the geometric features of trailing blades of return vanes in each of the first stage, the intermediate stage located between the first stage and the last stage, and the last stage in an embodiment of the present invention;
- the shape of the return vanes of only one stage of the centrifugal compressor should be considered.
- centrifugal compressor stage position of the multi-stage centrifugal compressor (in other words, for each stage) (a) the maximum camber position of the front blade, (b) the ratio of the maximum camber to the chord length of the front blade, (c) The angle formed by the trailing edge of the leading wing and the leading edge of the trailing wing in the circumferential direction around the centerline of the rotation shaft (circumferential direction angle ⁇ ), (d) The leading edge of the trailing wing and the trailing edge of the trailing wing It has been found that any one of the angles formed in the circumferential direction (circumferential direction angle ⁇ ) around the center line of the rotating shaft should be changed (optimized).
- a multi-stage centrifugal compressor that is an embodiment of the present invention will be described below with reference to the drawings.
- symbol is used for the same component.
- a multistage centrifugal compressor 100 includes a centrifugal impeller 1 that imparts rotational energy to a fluid, a rotating shaft 4 to which this centrifugal impeller 1 is attached, and a radially outer side of the centrifugal impeller 1. and a diffuser 5 for converting the dynamic pressure of the fluid discharged from the centrifugal impeller 1 into static pressure. Further, downstream of the diffuser 5, a return passage 6 is provided for guiding the fluid to the centrifugal impeller 1 in the latter stage.
- the centrifugal impeller 1 normally includes a disk (hub) fastened to the rotating shaft 4, a side plate (shroud) arranged opposite the hub, and a circumferential direction (Fig. 2 and a plurality of blades spaced apart in a direction perpendicular to the plane of FIG.
- a vaned diffuser having a plurality of blades arranged at substantially equal pitches in the circumferential direction or a vaneless diffuser having no blades is used.
- a vaned diffuser is used in FIG.
- the return passage 6 is composed of turning portions 7a and 7b for turning the flow of the fluid flowing through the diffuser 5 from the centrifugal direction to the axial direction and further turning from the axial direction to the return direction, and return vanes 8. (See FIG. 2), the return vanes 8 turn the fluid that has passed through the diffuser 5 from radially outward to inward. It plays the role of flowing into the centrifugal impeller 1 of the stage. As shown in FIG. 3, the return vanes 8 are arranged in a circular blade cascade around the centerline of the rotating shaft.
- the turning portions 7a and 7b turning from the axial direction to the return direction are formed as a U-shaped curved flow path surrounded by surrounding structures in the meridional plane.
- the turning portion 7a has a turning portion inlet 9 defined by a substantially cylindrical surface corresponding to the outlet of the diffuser 5, and a turning portion outlet 10 defined by a meridional curved flow path located immediately upstream of the return vane leading edge 12. It is defined as a section from the turning portion inlet 9 defined by a substantially cylindrical surface corresponding to the terminal end to the turning portion outlet 10 .
- the return vanes 8 are composed of a plurality of blades circumferentially arranged around the rotating shaft 4 at substantially equal pitches.
- radial bearings for rotatably supporting the rotating shaft 4 are arranged on both end sides of the rotating shaft 4 .
- centrifugal impellers (six centrifugal impellers in FIG. 1) 1 of multi-stage compressor stages are attached to the rotating shaft 4, and downstream of each centrifugal impeller 1, as shown in FIG. , a diffuser 5 and a return channel 6 are provided.
- the centrifugal impeller 1, diffuser 5 and return flow path 6 are housed in a casing 19 and a diaphragm 20, and the casing 19 is supported by flanges 21a and 21b.
- a suction flow path 15 is provided on the suction side of the casing 19
- a discharge flow path 16 is provided on the discharge side of the casing 19 .
- FIG. 4 is a diagram showing half of the state where the periphery of the return vanes 8 of an arbitrary stage in the multistage centrifugal compressor 100 of the embodiment of the present invention is viewed from the downstream side in the axial direction of the rotating shaft 4, and
- FIG. Fig. 3 is a schematic diagram showing the positional relationship between the leading blade 8A and the trailing blade 8B of the return vane 8 in the multistage centrifugal compressor 100 of the embodiment of the present invention;
- the return vanes 8 having multiple circular blade rows are arranged in two rows from the upstream side to the downstream side of the fluid flow in the return passage 6. It is a multi-stage centrifugal compressor with return vanes located in the In this embodiment, a plurality of airfoil-shaped return vanes 8 are installed in the return passage 6 in the circumferential direction on the upstream side and the downstream side in the return passage 6 as front blade rows and rear blade rows, respectively.
- the trailing blade 8B of the return vane 8 is circumferentially arranged on the pressure surface 8A1 side of the leading blade 8A. are offset in the direction of The fluid flowing near the pressure surface 8A1 of the front wing 8A has a thin and higher velocity boundary layer than the fluid flowing near the suction surface 8A5 of the front wing 8A. A fluid with energy is flowing.
- FIG. 6 to 8 are diagrams showing the shape features of the leading blade 8A of the return vane 8 in this embodiment.
- FIG. 6 shows the shape features of the front blade 8A in the first stage of the multistage centrifugal compressor 100 of this embodiment
- FIG. 8 shows the shape features of the front blade 8A in the stage
- FIG. 8 shows the shape feature of the front blade 8A in the final stage of the multi-stage centrifugal compressor 100 of this embodiment.
- the final stage of the multi-stage centrifugal compressor 100 refers to the final stage of the compressor stages having a return flow path (same below).
- a dashed line 8A6 shown in the figure indicates a chord line that is a straight line connecting the leading edge 8A3 and the trailing edge 8A2 of the leading blade 8A.
- a dotted line 8A4 shown in the drawing indicates the camber line of the front wing 8A (a line connecting points at equal distances from the upper and lower surfaces of the wing).
- An arrow 8A7 shown in the drawing indicates the camber of the front wing 8A, which is the distance from an arbitrary position of the chord line 8A6 to the camber line 8A4.
- an arrow 8A8 shown in the drawing indicates the maximum camber at which the camber of the front wing 8A is maximum.
- the maximum camber is represented as a ratio to the length of the chord line 8A6 (chord length L).
- the distance from the leading edge 8A3 of the leading blade 8A to the maximum camber 8A8 on the chord line 8A6 is called the maximum camber position lc ,max .
- the maximum camber position l c,max is expressed as a ratio to the chord length L (dimensionless chord position).
- the leading edge 8A3 of the leading blade 8A corresponds to the dimensionless chord position of 0%
- the trailing edge 8A2 corresponds to the dimensionless chord position of 100%.
- the ratio of the maximum camber 8A8 to the chord length L of the front blade 8A gradually increases toward the downstream stage.
- the ratio of the maximum camber 8A8 to the chord length L of the front blade 8A in (b) satisfies the above configuration of the maximum camber position lc ,max of the front blade 8A in (a) and is as described above. It is preferable to configure
- the effects of setting the front blades 8A of the multistage centrifugal compressor 100 in this way are as follows.
- the multistage centrifugal compressor 100 gradually pressurizes fluid from the first stage to the final stage. Therefore, due to the compressibility of the fluid to be compressed, the density of the fluid gradually increases from the first stage to the final stage. Therefore, the volumetric flow rate of the fluid flowing inside the multistage centrifugal compressor 100 is the highest at the first stage, and then gradually decreases toward the final stage.
- the turning angle of the fluid to be achieved by the return vane 8 (the difference between ⁇ rtv and ⁇ ) is the first stage of the multistage centrifugal compressor 100 is the smallest compared to the downstream stages and then gradually increases toward the downstream stages.
- the turning angle of the fluid achieved by the front blades 8A in the first stage of the multistage centrifugal compressor 100 is can be minimized, and then the fluid turning angle achieved by the front blades 8A can be gradually increased toward the downstream stage, and the different return vanes 8 at each stage can realize the fluid turning angle to be achieved. It becomes possible.
- the maximum camber position l c,max in any stage is the latter half of the chord line 8A6 (the trailing edge 8A2 side of the position corresponding to the dimensionless chord position 50%). is desirable. This effect is as follows.
- the camber line 8A4 of the front wing 8A is sharply curved near the trailing edge 8A2. Therefore, as shown in FIG. 5, the direction of flow along the pressure surface 8A1 of the front blade 8A is the direction toward the suction surface 8B1 of the rear blade 8B. This flow presses the flow along the suction surface 8B1 of the trailing blade 8B toward the blade surface, thereby suppressing separation of the flow occurring on the suction surface 8B1 of the trailing blade 8B. By suppressing the separation of the flow, it is possible to achieve both the suppression of efficiency reduction due to the separation and the turning of the flow.
- the camber line 8A4 of the front blade 8A is sharply curved, the flow tends to separate at the suction surface 8A5 of the front blade 8A in the vicinity thereof. is limited to the vicinity of the trailing edge 8A2, the peeling area of the suction surface 8A5 is limited to the vicinity of the trailing edge 8A2. Therefore, it is possible to effectively suppress flow separation on the suction surface 8B1 of the trailing wing 8B while minimizing an increase in pressure loss in the leading wing 8A.
- the maximum camber position lc ,max of the leading blade 8A gradually moves from the trailing edge 8A2 side to the leading edge 8A3 side.
- the shape of the leading blade 8A of the return vane 8 has been described so that the maximum camber 8A8 of the blade 8A gradually increases.
- the maximum camber position l c,max of the front blade 8A may be the same in two or more adjacent stages of the multi-stage centrifugal compressor 100 .
- the maximum camber 8A8 of the front blade 8A may be the same in two or more adjacent stages of the multi-stage centrifugal compressor 100.
- FIG. the maximum camber position l c,max of the first stage front blade 8A is positioned closest to the trailing edge 8A2 side at least in comparison with the final stage when viewed from the first stage, and the maximum camber position l c,max of the final stage front blade 8A lc ,max is positioned closest to the leading edge 8A3, or the maximum camber 8A8 of the first-stage front wing 8A is the smallest, and the maximum camber 8A8 of the final-stage front wing 8A is the largest.
- the front blade 8A of the return vane 8 may be configured as shown.
- FIG. 10 shows a pair of front blades 8A that constitute the return vanes 8 at the first stage, the intermediate stage between the first stage and the final stage, and the final stage of the multistage centrifugal compressor 100 in this embodiment.
- the left side of FIG. 10 shows the first stage
- the center of FIG. 10 shows the intermediate stage
- the right side of FIG. 10 shows the final stage.
- the circumferential angle ⁇ at the first stage is the circumferential angle ⁇ at the first stage
- ⁇ M shown in the center of FIG. 10 is the circumferential angle ⁇ at the intermediate stage
- ⁇ L shown in the right side of FIG. 10 represents the magnitude of the circumferential angle ⁇ at the final stage.
- the circumferential angle ⁇ is largest at the first stage of the multi-stage centrifugal compressor 100, and gradually decreases toward the downstream stages. , becomes smallest at the final stage, that is, the front wing 8A and the rear wing 8B are configured so that ⁇ F > ⁇ M > ⁇ L.
- the effect of setting the circumferential angle ⁇ of the multistage centrifugal compressor 100 as described above is as follows. That is, in order to suppress the flow separation occurring on the suction surface 8B1 of the trailing blade 8B, the pressure surface 8A1 of the trailing blade 8A and the pressure surface 8B1 of the trailing blade 8B should be separated from each other.
- the flow from the pressure surface 8A1 of the front blade 8A is placed near the front half of the blade where the deceleration of the flow velocity on the blade surface is the largest on the suction surface 8B1 and separation is likely to occur.
- the tool deforms due to insufficient rigidity when the tool is pressed against the object to be machined, and machining becomes impossible. Therefore, according to the blade heights in the vicinity of the rear half of the front blade 8A and the front half of the rear blade 8B, the rear half of the pressure surface 8A1 of the front blade 8A and the front half of the suction surface 8B1 of the rear blade 8B It is determined whether or not the width of the flow path formed between the blades of the part can be processed.
- the volumetric flow rate of the fluid flowing inside the multi-stage centrifugal compressor 100 is the highest at the first stage, and then gradually decreases toward the final stage.
- the width of the flow path is adjusted according to the magnitude of the volumetric flow rate so that the flow velocity of the fluid flowing through the return vane 8 does not become too high.
- the front blade 8A and the rear blade 8B are configured to have a wider passage width in the stage with a large volumetric flow rate than in the stage with a small volumetric flow rate.
- the front wing 8A and the rear wing 8B are arranged so that the blade height in the vicinity of the rear half of the front wing 8A and the front half of the rear wing 8B is also highest at the first stage and gradually decreases toward the final stage.
- the circumferential angle ⁇ is configured to satisfy ⁇ F > ⁇ M > ⁇ L as in this embodiment, the rear half of the pressure surface 8A1 of the front blade 8A and the suction surface 8B1 of the rear blade 8B Since the width of the flow passage formed between the blades in the front half of the blade gradually decreases from the first stage to the final stage, the width of the flow passage is appropriate considering both the suppression of separation and securing the rigidity of the processing tool. can be set.
- the circumferential angle ⁇ when the Mach number of the fluid to be compressed by the multistage centrifugal compressor 100 is low and the influence of the compressibility of the fluid can be almost ignored, two or more adjacent multistage centrifugal compressors 100 , the circumferential angle ⁇ may be the same.
- the leading wing 8A and the trailing wing 8B are configured so that the circumferential angle ⁇ of the first stage is the largest and the circumferential angle ⁇ of the final stage is the smallest at least in comparison with the last stage when viewed from the first stage. You can do it.
- FIG. 5 shows the shape characteristics of the trailing blade 8B that constitutes the return vane 8 of the multistage centrifugal compressor 100 in this embodiment.
- Circumferential direction angle ⁇ shown in FIG. 5 is defined by a straight line connecting the center line of rotating shaft 4 and leading edge 8B2 of trailing blade 8B, and the center line of rotating shaft 4 and trailing edge 8B3 of trailing blade 8B. It represents the angle formed in the circumferential direction with the straight line connecting the
- FIG. 11 shows the shape of the trailing blade 8B that constitutes the return vane 8 at the first stage, the intermediate stage between the first stage and the final stage, and the final stage of the multistage centrifugal compressor 100 in this embodiment.
- FIG. 11 shows the initial stage
- the center of FIG. 11 shows the intermediate stage between the initial stage and the final stage
- the right side of FIG. 11 shows the final stage.
- ⁇ F shown in the left side of FIG. 11 is the circumferential angle ⁇ at the first stage
- ⁇ M shown in the center of FIG. 11 is the circumferential angle ⁇ at the intermediate stage.
- .theta.L shown in the drawing on the right side of FIG. 11 represent the magnitude of the circumferential angle .theta.
- (d) the magnitude of the circumferential angle ⁇ is greatest at the first stage of the multi-stage centrifugal compressor 100, and then gradually decreases toward the downstream stages. , becomes smallest at the final stage, that is, the trailing blade 8B is configured so that ⁇ F > ⁇ M > ⁇ L .
- the effect of setting the circumferential angle ⁇ of the multistage centrifugal compressor 100 as described above is as follows.
- the circumferential angle ⁇ when the Mach number of the fluid compressed by the multistage centrifugal compressor 100 is low and the influence of the compressibility of the fluid can be almost ignored, two or more adjacent multistage centrifugal compressors 100 , the circumferential angle ⁇ may be the same.
- the trailing blade 8B may be configured so that the circumferential angle ⁇ of the first stage is the largest and the circumferential angle ⁇ of the final stage is the smallest in comparison with at least the final stage when viewed from the first stage. .
- centrifugal compressor 100 of the present embodiment it is possible to maintain and improve efficiency while reducing the outer diameter of the static flow path, so that cost reduction and improvement in operational efficiency can be expected.
- By reducing the outer diameter it is also possible to reduce the area occupied by the centrifugal compressor 100 in the field.
- the present invention is not limited to the above-described embodiments, and includes various modifications.
- the above-described embodiments have been described in detail to facilitate understanding of the present invention, and are not necessarily limited to those having all the described configurations.
- it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment and it is also possible to add the configuration of another embodiment to the configuration of one embodiment.
- Return vane trailing blade 8B1 Return vane trailing blade 8B1 ... Return Suction surface of trailing blade of vane 8B2 Leading edge of trailing blade of return vane 8B3 Trailing edge of trailing blade of return vane 8B4 Pressure surface of trailing blade of return vane 9 Turning portion inlet , 10... Turning portion outlet, 12... Return vane leading edge, 15... Suction channel, 16... Discharge channel, 19... Casing, 20... Diaphragm, 21a, 21b... Flange, 100... Multi-stage centrifugal compressor, C...
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Abstract
Description
しかし、遠心圧縮機の更なる小型化を考えた場合においては、これらの翼単独の形状のみを考慮するだけでは、個々の翼に作用する負荷が過大となるため、ただ翼を二重、三重に設けても、流れが翼面から剥離してしまう恐れがあり、効率の向上が図れない可能性がある。
本発明における多段遠心圧縮機の具体的な一例は、回転軸と、前記回転軸に取り付けられた複数の遠心羽根車を備え、前記複数の遠心羽根車の一つと、前記一つの遠心羽根車から流出した流体が前記回転軸から離れる遠心方向に流れるディフューザと、前記ディフューザの下流に設けられ、前記ディフューザから前記複数の遠心羽根車の後段の遠心羽根車に流入する前記流体が前記回転軸に向かう戻り方向に流れるリターン流路と、前記ディフューザを流れた前記流体の流れが前記遠心方向から前記回転軸の軸方向に転向し、更に、前記軸方向から前記戻り方向に転向する転向部を備えた遠心圧縮機段が、前記回転軸方向に複数連ねられた多段遠心圧縮機であって、前記リターン流路は、前記回転軸の中心線を中心とする円形翼列状に配設された複数のリターンベーンを備え、前記リターンベーンは、前記リターン流路における前記流体の流れの上流側から下流側に向かって、前置翼と後置翼として複数設置され、前記後置翼の負圧面に前記前置翼の圧力面側の流れを導くように、前記後置翼は前記前置翼の圧力面側に周方向にオフセットして設けられ、前記前置翼の最大キャンバー位置、前記前置翼の後縁と前記後置翼の前縁が前記回転軸の中心線を中心として円周方向になす周方向角度γ、前記後置翼の前縁と後縁が前記回転軸の中心線を中心として円周方向になす周方向角度θの少なくとも何れか一つを多段遠心圧縮機の遠心圧縮機段位置に応じて変更したものである。
上記した以外の課題、構成及び効果は、以下の実施形態の説明により明らかにされる。
圧縮性を有する各種の気体を昇圧する多段遠心圧縮機では、上流側の遠心圧縮機段から下流側の遠心圧縮機段に向かい、気体の圧力が徐々に上昇していく。そのため、上流側の遠心圧縮機段から下流側の遠心圧縮機段に向かい、気体の圧縮性の影響により気体の密度は徐々に増大していき、逆に気体の体積流量は徐々に減少する。多段遠心圧縮機では、このように各段を通過する気体の体積流量が異なるため、段毎に内部流路中の気体の流動状態も異なる。本発明者等の検討によれば、多段遠心圧縮機の更なる小型化において、リターンベーンでの流れの剥離を回避するためには、ある一つの遠心圧縮機段のみのリターンベーンの形状を考慮するだけではなく、段毎の気体の流動状態の差までも考慮した形状の検討が必要となる。
そこで、本発明者等は種々検討した結果、リターンベーンとして二重に翼列(前置翼列と後置翼列)を備えた多段遠心圧縮機において、各段での体積流量の相違を考慮して、多段遠心圧縮機の遠心圧縮機段位置に応じて(言い換えれば段毎に)(a)前置翼の最大キャンバー位置、(b)前置翼の翼弦長に対する最大キャンバーの比、(c)前置翼の後縁と後置翼の前縁が回転軸中心線を中心として円周方向になす角(周方向角度γ)、(d)後置翼の前縁と後縁が回転軸中心線を中心として円周方向になす角(周方向角度θ)の何れかを変更(最適化)すれば良いことを見出した。
図1に示すように、多段遠心圧縮機100は、回転エネルギーを流体に付与する遠心羽根車1と、この遠心羽根車1が取り付けられる回転軸4と、遠心羽根車1の半径方向外側にあって遠心羽根車1から流出された流体の動圧を静圧へと変換するディフューザ5とから概略構成されている。また、ディフューザ5の下流には、後段の遠心羽根車1へ流体を導くためのリターン流路6が設けられている。
図4は、本発明の実施例の多段遠心圧縮機100における任意の段のリターンベーン8の周辺を回転軸4の軸方向の下流側から見た状態の半分を示す図であり、図5は、本発明の実施例の多段遠心圧縮機100におけるリターンベーン8の前置翼8Aと後置翼8Bの位置関係を示す模式図である。
翼弦線8A6上において、前置翼8Aの前縁8A3から最大キャンバー8A8に至るまでの距離を、最大キャンバー位置lc,maxと呼ぶ。最大キャンバー位置lc,maxは、翼弦長Lに対する割合(無次元翼弦位置)で表される。ここで、前置翼8Aの前縁8A3は無次元翼弦位置が0%の位置に、後縁8A2は無次元翼弦位置が100%の位置に、それぞれ相当する。
多段遠心圧縮機100は、初段から最終段まで流体を徐々に昇圧する。従って、圧縮する流体の圧縮性により、初段から最終段にかけて流体の密度が徐々に増大する。このため、多段遠心圧縮機100の内部を流れる流体の体積流量は、初段が最も多く、それから最終段に向かうにつれて徐々に少なくなる。
理論ヘッドHth=U2×Cu2/g ・・・ 式(1)
ここで、U2は各段の羽根車の周速を、Cu2は各段の羽根車出口における流体の絶対速度の周方向成分を、gは重力加速度を、それぞれ表す。各段の理論ヘッドHthを同等に構成する場合には、各段ともU2およびCu2が同等になる。従って、前置翼8Aの入口付近における速度三角形中に示される、絶対速度の周方向成分Cuも、各段とも同等になるように構成されることになる。
即ち、後置翼8Bの前記負圧面8B1で生じる流れの剥離の抑制のためには、前置翼8Aの圧力面8A1の後半部と、後置翼8Bの負圧面8B1の前半部の翼間に構成される流路の幅をなるべく狭めるとともに、負圧面8B1上において最も翼面上の流速の減速が大きくなり剥離が生じやすい翼の前半付近に、前置翼8Aの圧力面8A1からの流れを向けることが最も有効である。一方この、前置翼8Aの圧力面8A1の後半部と、後置翼8Bの負圧面8B1の前半部の翼間に構成される流路の幅を狭め過ぎると、この部位を切削加工する際に小径の加工工具を用いて切削せざるを得なくなり、加工性が悪化する。特に、この部位の翼高さ(子午断面図におけるリターンベーン8の流路幅と同義)が高い場合には(初段で高くなる)、この部位を切削する際に、小径で工具長さの長く剛性の低い工具を用いなければならなくなる。工具の剛性が十分確保できない場合には、工具を加工対象物に押し当てる際に、剛性が足りずに工具が変形し、加工ができなくなる。従って、前置翼8Aの後半部と前記後置翼8Bの前半部付近における翼高さに応じて、前置翼8Aの圧力面8A1の後半部と、後置翼8Bの負圧面8B1の前半部の翼間に構成される流路の幅の加工可否が決定される。
例えば、上述した実施例は本発明を分かりやすく説明するために詳細に説明したものであり、必ずしも説明したすべての構成を備えるものに限定されるものではない。また、ある実施例の構成の一部を他の実施例の構成に置き換える事が可能であり、また、ある実施例の構成に他の実施例の構成を加える事も可能である。また、各実施例の構成の一部について、他の構成の追加・削除・置換をする事が可能である。
例えば、(a)前置翼の最大キャンバー位置、(b)前置翼の翼弦長に対する最大キャンバーの比、(c)前置翼の後縁と後置翼の前縁が回転軸中心線を中心として円周方向になす角(周方向角度γ)、(d)後置翼の前縁と後縁が回転軸中心線を中心として円周方向になす角(周方向角度θ)については、(a)、(c)、(d)の少なくとも一つの前述した特徴を備えていれば良い。もちろん、(a)、(c)、(d)の何れか二つ、又は全ての特徴を備えるようにすることにより、より大きな効果が得られる。
Claims (15)
- 回転軸と、前記回転軸に取り付けられた複数の遠心羽根車を備え、
前記複数の遠心羽根車の一つと、前記一つの遠心羽根車から流出した流体が前記回転軸から離れる遠心方向に流れるディフューザと、前記ディフューザの下流に設けられ、前記ディフューザから前記複数の遠心羽根車の後段の遠心羽根車に流入する前記流体が前記回転軸に向かう戻り方向に流れるリターン流路と、前記ディフューザを流れた前記流体の流れが前記遠心方向から前記回転軸の軸方向に転向し、更に、前記軸方向から前記戻り方向に転向する転向部を備えた遠心圧縮機段が、前記回転軸の軸方向に複数連ねられた多段遠心圧縮機であって、
前記リターン流路は、前記回転軸の中心線を中心とする円形翼列状に配設された複数のリターンベーンを備え、
前記リターンベーンは、前記リターン流路における前記流体の流れの上流側から下流側に向かって、前置翼と後置翼として複数設置され、
前記後置翼の負圧面に前記前置翼の圧力面側の流れを導くように、前記後置翼は前記前置翼の圧力面側に周方向にオフセットして設けられ、
前記前置翼の最大キャンバー位置、前記前置翼の後縁と前記後置翼の前縁が前記回転軸の中心線を中心として円周方向になす周方向角度γ、前記後置翼の前縁と後縁が前記回転軸の中心線を中心として円周方向になす周方向角度θの少なくともの何れか一つを多段遠心圧縮機の遠心圧縮機段位置に応じて変更したことを特徴とする多段遠心圧縮機。 - 請求項1に記載の多段遠心圧縮機において、
前記リターンベーンのうちで最も上流側の遠心圧縮機段のリターン流路に設けられる前記前置翼の最大キャンバー位置が最も後縁側に位置するとともに、前記リターンベーンのうちで最も下流側の遠心圧縮機段のリターン流路に設けられる前記前置翼の最大キャンバー位置が最も前縁側に位置することを特徴とする多段遠心圧縮機。 - 請求項2に記載の多段遠心圧縮機において、
前記前置翼の最大キャンバー位置が下流側の遠心圧縮機段に行くにつれて徐々に前記前置翼の前縁方向に移動することを特徴とする多段遠心圧縮機。 - 請求項2に記載の多段遠心圧縮機において、
最も上流側の遠心圧縮機段と最も下流側の遠心圧縮機段の間において、前記前置翼の最大キャンバー位置が下流側の段とその直前の上流側の段とで同一位置にあることを特徴とする多段遠心圧縮機。 - 請求項2乃至4の何れか一項に記載の多段遠心圧縮機において、
何れの遠心圧縮機段においても、前記前置翼の最大キャンバー位置が、前記前置翼の翼弦線の後半部にあることを特徴とする多段遠心圧縮機。 - 請求項2乃至4の何れか一項に記載の多段遠心圧縮機において、
前記リターンベーンのうちで最も上流側の遠心圧縮機段のリターン流路に設けられる前記前置翼の翼弦長に対する最大キャンバーの比が最も小さく、前記リターンベーンのうちで最も下流側の遠心圧縮機段のリターン流路に設けられる前記前置翼の翼弦長に対する最大キャンバーの比が最も大きくなることを特徴とする多段遠心圧縮機。 - 請求項2乃至4の何れか一項に記載の多段遠心圧縮機において、
何れの遠心圧縮機段においても、前記前置翼の最大キャンバー位置が、前記前置翼の翼弦線の後半部にあり、
前記リターンベーンのうちで最も上流側の遠心圧縮機段のリターン流路に設けられる前記前置翼の翼弦長に対する最大キャンバーの比が最も小さく、前記リターンベーンのうちで最も下流側の遠心圧縮機段のリターン流路に設けられる前記前置翼の翼弦長に対する最大キャンバーの比が最も大きくなることを特徴とする多段遠心圧縮機。 - 請求項6に記載の多段遠心圧縮機において、
前記前置翼の翼弦長に対する最大キャンバーの比が下流側の遠心圧縮機段に行くにつれて徐々に大きくなることを特徴とする多段遠心圧縮機。 - 請求項6に記載の多段遠心圧縮機において、
最も上流側の遠心圧縮機段と最も下流側の遠心圧縮機段の間において、前記前置翼の翼弦長に対する最大キャンバーの比が下流側の段とその直前の上流側の段とで同一であることを特徴とする多段遠心圧縮機。 - 請求項1に記載の多段遠心圧縮機において、
前記前置翼の後縁と前記後置翼の前縁が前記回転軸の中心線を中心として円周方向になす周方向角度γが、前記リターンベーンのうちで最も上流側の遠心圧縮機段のリターン流路に設けられる前記リターンベーンで最も大きく、前記リターンベーンのうちで最も下流側の遠心圧縮機段のリターン流路に設けられる前記リターンベーンで最も小さいことを特徴とする多段遠心圧縮機。 - 請求項10に記載の多段遠心圧縮機において、
前記周方向角度γが下流側の遠心圧縮機段に行くにつれて徐々に小さくなることを特徴とする多段遠心圧縮機。 - 請求項10に記載の多段遠心圧縮機において、
最も上流側の遠心圧縮機段と最も下流側の遠心圧縮機段の間において、前記周方向角度γが下流側の段とその直前の上流側の段とで同一であることを特徴とする多段遠心圧縮機。 - 請求項1に記載の多段遠心圧縮機において、
前記後置翼の前縁と後縁が前記回転軸の中心線を中心として円周方向になす周方向角度θが、前記リターンベーンのうちで最も上流側の遠心圧縮機段のリターン流路に設けられる前記リターンベーンで最も大きく、前記リターンベーンのうちで最も下流側の遠心圧縮機段のリターン流路に設けられる前記リターンベーンで最も小さいことを特徴とする多段遠心圧縮機。 - 請求項13に記載の多段遠心圧縮機において、
前記周方向角度θが下流側の遠心圧縮機段に行くにつれて徐々に小さくなることを特徴とする多段遠心圧縮機。 - 請求項13に記載の多段遠心圧縮機において、
最も上流側の遠心圧縮機段と最も下流側の遠心圧縮機段の間において、前記周方向角度θが下流側の段とその直前の上流側の段とで同一であることを特徴とする多段遠心圧縮機。
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JP2015094293A (ja) | 2013-11-12 | 2015-05-18 | 株式会社日立製作所 | 遠心形ターボ機械 |
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