EP3211245A1 - Enveloppe à volute pour pompe centrifuge - Google Patents

Enveloppe à volute pour pompe centrifuge Download PDF

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Publication number
EP3211245A1
EP3211245A1 EP16156930.6A EP16156930A EP3211245A1 EP 3211245 A1 EP3211245 A1 EP 3211245A1 EP 16156930 A EP16156930 A EP 16156930A EP 3211245 A1 EP3211245 A1 EP 3211245A1
Authority
EP
European Patent Office
Prior art keywords
volute casing
centreline
outlet opening
outlet duct
outlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP16156930.6A
Other languages
German (de)
English (en)
Inventor
Heikki Manninen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sulzer Management AG
Original Assignee
Sulzer Management AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sulzer Management AG filed Critical Sulzer Management AG
Priority to EP16156930.6A priority Critical patent/EP3211245A1/fr
Publication of EP3211245A1 publication Critical patent/EP3211245A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F04D29/426—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for liquid pumps
    • 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
    • F04D29/426—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for liquid pumps
    • F04D29/428—Discharge tongues
    • 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
    • F04D29/426—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for liquid pumps
    • F04D29/4293—Details of fluid inlet or outlet

Definitions

  • the present invention relates to a volute casing for a centrifugal pump.
  • the volute casing of the invention is especially applicable in connection with centrifugal pumps where the efficiency of the pump plays a role in the pump design.
  • the present centrifugal pumps use, in principle, two types of volute casings in view of the positioning of the outlet opening.
  • industrial standards ISO2858 and EN733 concerning small centrifugal pumps suggest that the outlet duct and the outlet openings of the centrifugal pumps are positioned on the vertical centreline of the centrifugal pump, i.e. on the vertical line running via the axis of the pump and its rotor.
  • outlet duct and outlet opening result in a low efficiency for two separate reasons. Firstly, there is a substantially sharp bend in the outlet duct, i.e. a bend turning the flow of the medium abruptly from circumferential direction to radial direction, causing significant resistance to flow. And secondly, the outlet duct is relatively long, as it is common practice to arrange a widening part, i.e. a diffuser, to the outlet duct for matching the outlet duct to the following pipeline. Since the pump is normally made by casting the non-smooth cast inside surface of the outlet duct causes high friction losses between the flowing medium and the cast surface. In other words, the volute casing design downstream of the cut-water tongue adds flow resistance.
  • the outlet duct of the present centrifugal pump is much more expensive to manufacture than a corresponding length of pipe in the pipeline taking the medium further.
  • the cast outlet duct is much heavier than a corresponding length of pipe in the pipeline.
  • the pump outlet takes also due to its long outlet duct a considerable space in the direction of the outlet duct, i.e. normally in vertical direction.
  • the additional weight and dimensions are clear drawbacks in all phases of taking the pump into use starting from the manufacture of the pump and ending to the installation thereof.
  • the positioning of the outlet of the centrifugal pump suggested by the standards have the advantage that the volute casing of the pump is self-deaerating, i.e. when the pump is filled with liquid almost all the gas/air is discharged from the volute casing to the outlet.
  • Another advantage may be seen in the way the vertical forces acting on the centrifugal pump are affecting the construction of the centrifugal pump.
  • the forces act along the centreline of the centrifugal pump in the middle between the legs of the centrifugal pump, whereby the centrifugal pump is stabile in relation to vertical forces. This means that the legs of the pump may be positioned rather close to each other, i.e. at a short distance from the centreline.
  • the amount of material needed for the legs is small and that the base plate and the concrete foundation of the base plate and the pump may be designed small.
  • the construction of the pump itself due to the positioning and length of the outlet duct, it has to be supported often to the volute casing by means of one or more strengthening ribs, especially if friable material like for instance cast iron is used in the manufacture of the volute casing.
  • the second example of the volute casing construction is a traditional centrifugal pump having a tangential outlet, the efficiency ratio of which is 3 - 5 percentage units higher than the centrifugal pumps of the first example.
  • the centrifugal pumps having a tangential outlet have a few disadvantages, like for instance the construction of a small centrifugal pump, which requires a very long outlet duct and which is difficult to manufacture due to the complicated construction of the cut-water tongue.
  • the pumps having tangential outlets are always equipped with a diffuser in the outlet duct, meaning that the outlet duct expands conically. This kind of a structure increases both the production costs and the weight of the pump significantly. Also, the friction losses are high due to a long cast outlet duct.
  • an object of the present invention is to eliminate at least one of the above mentioned drawbacks or problems by means of a novel volute casing for a centrifugal pump.
  • Another object of the present invention is to develop a novel volute casing that maintains the efficiency of the centrifugal pump at a high level.
  • a further object of the present invention is to develop a novel volute casing that makes it possible to reduce the weight and dimensions of a centrifugal pump and thereby also the material costs in the production thereof.
  • a yet further object of the present invention is to develop a novel volute casing that makes it possible to reduce the size of the base plate and concrete foundation compared to prior art pumps capable of high efficiency.
  • the present invention brings about a number of advantages, like for instance
  • volute casing for a centrifugal pump of the present invention is described more in detail below, with reference to the accompanying drawings, of which
  • FIG 1 illustrates as a first example of prior art centrifugal pumps a radial cross section of a volute casing 4 of a centrifugal pump constructed in accordance with industrial standards ISO2858 and EN733.
  • the volute casing 4 is supported of its wall 2 by means of legs 6 to the installation base plate 8.
  • the volute casing 4 comprises an outlet duct 10, an outlet opening 12 and a cut-water tongue 14.
  • the outlet duct 10 and the outlet opening 12 are positioned on the vertical centreline C L of the centrifugal pump, the centreline running via the axis of the volute casing and the rotor (shown by broken circle).
  • the centreline C L of the centrifugal pump is considered to run via the axis of the volute casing in a direction perpendicular to the plane of the outlet opening or the outlet flange.
  • the legs 6 may be arranged symmetrically to the vertical centreline C L and substantially close to one another on the installation base plate 8. This reduces the material and manufacturing costs of the centrifugal pump - installation base plate combination.
  • the concrete foundation on which the installation base plate is located may be made small if the base plate is small.
  • outlet duct 10 and outlet opening 12 result in a low efficiency, as there is an extra sharp bend 16 in the flow path from the volute to the outlet opening 12 causing resistance to flow.
  • volute casing design downstream of the cut-water tongue 14 adds flow resistance, too, as the outlet duct made by means of casting has a relatively rough inside surface and the outlet duct is relatively long (its length normally equalling to about a half of the average radius of the volute casing) and thus the friction losses against the cast duct surface are substantially high.
  • the overall effect of the entire outlet duct is of the order of 3 - 5 percentage units' reduction in the efficiency ratio compared to pumps having a tangential outlet duct.
  • the outlet duct 10 and outlet opening 12 of the present centrifugal pump are also expensive to manufacture, and take due to the substantially long outlet duct 10 a considerable space in the direction of the outlet duct, i.e. normally in vertical direction.
  • the outlet duct 10 it has to be supported by means of at least one strengthening rib 18 to the wall 2 of the volute casing 4, especially if friable material like for instance cast iron is used in the manufacture of the volute casing 4.
  • the long outlet duct which is made to widen in the flow direction forms a considerable weight increase.
  • FIG. 2 illustrates, as a second example of prior art centrifugal pumps, a radial cross section of a volute casing 24 of a centrifugal pump.
  • the second example is a traditional centrifugal pump having a tangential outlet 30, whereby the vertical centreline C LOT of the outlet duct 30 and the outlet opening 32 are relatively far from the vertical centreline C L running via the axis of the volute casing 24.
  • This kind of a construction means that the legs 26 of the centrifugal pump have to extend farther away from the vertical centreline C L of the volute casing 24, at least so that the leg 26 situated on the same side of the volute 24 with the outlet duct 30 extends clearly outside the vertical centreline C LO of the outlet duct 30.
  • centrifugal pumps having a tangential outlet 30 have themselves a few disadvantages, like for instance the construction of a small centrifugal pump, which requires a very long (its length normally equalling to about a half of the average radius of the volute casing) conically expanding outlet duct 30 (diffuser), and which is difficult to manufacture due to the complicated construction of the cutwater tongue 34.
  • the same friction-related problems that relate to the centrifugal pumps of the above mentioned standards concern also these pumps having a tangential outlet duct, i.e. the long cast surface causes high frictional losses.
  • when such a pump is filled with liquid gas/air remains in the upper part of the volute casing whereby an additional degassing duct is required in the volute casing.
  • At least some of the above discussed problems or disadvantages may be obviated by trying to minimize the weight of the centrifugal pump, the dimensions of the centrifugal pump and the friction losses in the outlet duct.
  • the above goals may be reached by designing the volute casing of a centrifugal pump to have as short outlet duct as possible.
  • the length of the outlet duct may be measured from the cutwater tongue to the outlet flange. Minimizing the length of the outlet duct so that no additional flow losses are created requires that the outlet duct and the outlet opening of the centrifugal pump are located between the vertical centrelines discussed in connection with Figures 1 and 2 , i.e.
  • a further advantageous feature of the outlet duct of the present invention is such that the cross sectional flow area of the outlet duct remains substantially constant from the cutwater tongue area to the outlet collar. This feature minimizes the weight of the outlet duct as well as the cast surface area causing the frictional losses.
  • FIG 3 illustrates a radial cross section of a volute casing 44 of a centrifugal pump in accordance with a preferred embodiment of the present invention.
  • the exemplary centrifugal pump of Figure 3 comprises a volute casing 44 having a wall 42, an outlet duct 50, an outlet opening 52 and a cutwater tongue 54.
  • the volute casing 44 is supported by means of legs 46 fastened to or being integral parts of the wall 42 of the volute casing 44 on an installation base plate 48.
  • the volute casing 44 has a vertical centreline C L , and the outlet opening 52 a vertical centreline C LO .
  • the centreline C L of the centrifugal pump runs via the axis of the volute casing 44 in a direction perpendicular to the plane of the outlet opening 52 or the surface 56' of the outlet collar 56.
  • the vertical centreline C LO runs via the centre of the outlet opening 52 in a direction perpendicular to the plane of the outlet opening 52 or the surface 56' of the outlet collar 56.
  • Figure 3 shows also by means of a line C LOT running in a direction perpendicular to the plane of the outlet opening 52 or the surface 56' (against which the pipeline is attached) of the outlet collar 56 the position of a centreline of the outlet duct if the outlet were a tangential one in accordance with prior art (like shown in Fig. 2 ).
  • the centreline C LO of the outlet opening 52 of the volute casing of the present invention is within a distance D of between 0,25 * C and 0,8 * C, preferably between 0,4 * C and 0,75 * C from the centreline C L of the volute casing 44, where C is the distance from the axis of the volute casing 44 to the tip of the cutwater tongue 54 of the volute casing.
  • the length L of the outlet duct 50 measured along the centreline C LOD (see Figure 5 ) of the outlet duct 50 is between 0,1 - 0,6 * C, preferably between 0,2 - 0,4 * C, where C is the distance from the axis A of the volute casing 44 to the tip of the cutwater tongue 54 of the volute casing 44.
  • the outlet duct 50 has, preferably, a substantially constant cross section for all of its length, i.e. from the level of the cutwater tongue 54 to the outlet opening 52, i.e. to the level of the collar surface 56'.
  • the word 'substantially' is used here to take into account minor changes in the cross section due to constructional or manufacture-related issues.
  • the cross sectional area of the outlet duct or pressure conduit should be substantially constant and have a cross sectional form of a circle, whereas the cross sectional shape of the volute casing in prior art pumps has usually an oval or, in most cases, a rectangular shape at the cutwater tongue area.
  • the lengthy outlet duct is needed for converting the oval or rectangular cross sectional shape of the volute casing to a substantially round shape at the outlet opening.
  • the present invention represents new thinking by introducing a volute casing whose cross section is formed such that the cross section of the inner wall of the volute casing is substantially circular at the area of the cutwater tongue.
  • Figure 4 shows, just for clarification, how the radial centreline plane of the volute casing 44 used in Figures 3 and 5 is defined.
  • Figure 4 illustrates a cross section B - B of the volute casing of Figure 3 .
  • the radial centreline plane C LV is running in a radial direction at right angles to the axis A (see Fig. 3 ) half-way between the axially outer extremities of the impeller 60 at the radially outer circumference C OI of the impeller 60.
  • the impeller is provided with both working vanes 62 and rear vanes 64
  • the above mentioned outer extremities of the impeller 60 are the free tips 62' of the working vanes 62 and those 64' of the rear vanes 64 at the radially outer circumference C OI of the vanes 62 and 64.
  • the impeller has only the working vanes and a shroud 66
  • the extremities are the free tips 62' of the working vanes 62 and the edge 66' of the shroud 66 facing away from the working vanes 62 at the radially outer circumference of the impeller 60.
  • it is a question of a closed impeller the extremities are the free tips of the front and rear pump out vanes at the radially outer circumference of the impeller. Etc.
  • Figure 5 illustrates schematically the design of the volute casing 44 of the present invention, i.e. especially the configuration of the pressure conduit or the outlet duct 50.
  • Figure 5 illustrates a radial cross section of the volute casing 44, i.e. a cross section running along a radial centreline plane C LV (see Fig. 4 ) of the volute casing 44. Since a goal of the present invention is to minimize flow losses of a centrifugal pump, a way to improve the pump performance is to provide the outlet duct 50 with a constant circular cross section from the level L CT (at right angles to the centreline C LOD of the outlet duct) of the cutwater tongue 54 to the plane L OO of the outlet opening 52.
  • the general longitudinal direction of the outlet duct 50 is at the plane L OO of the outlet opening 52 at right angles to the plane L OO of the outlet opening 52.
  • the outlet duct 50 when moving against the direction of the fluid flow towards the interior of the pump, starts turning to a side of the impeller 60 immediately below the plane L OO of the outlet opening 52, yet maintaining its cross sectional shape and area up to the level L CT defined by a line running from the tip of the cutwater tongue 54 to the centre C P (of curvature of the centreline C LOD of the outlet duct 50).
  • the centreline C LOD of the outlet duct 50 may be bent along any such curve that keeps the flow losses minimal.
  • the curved centreline C LOD may follow a circle, whereby the opposite surfaces 50 SI and 50 SO of the outlet duct 50 in the centreline plane C LV (see Figure 3 ) are parts of a circle having a centre at C P , too.
  • the inner surface 70 of the wall 42 of the volute casing 44 joins tangentially in point S to the surface 50 SO .
  • the radius R of the centreline C LOD of the outlet duct (between the plane L OO and the level L CT ) is preferably longer than the radius R O of the outlet opening.
  • R is from 1.2 to 3 times R O , more preferably R is from 1.2 to 2.5 times R O , most preferably R is from 1.25 to 2.0 times R O .
  • the ellipses sketched in the outlet duct/volute casing represent the round or circular cross sectional area of the volute casing in different positions of the cross section.
  • the two uppermost ellipses have the same cross sectional area, and the third one already somewhat smaller area due to the continuous convergence of the cross sectional area of the volute casing in the direction opposite to the flow direction in the volute casing 44 from the level L CT of the cutwater tongue 54 up to below the cutwater tongue 54 where the cross sectional area it at its smallest.
  • volute casing is preferably positioned such that the centreline of the outlet opening is opposite to the legs of the volute casing, whereby a natural way to install the volute casing, and the pump, is such that the centreline of the outlet opening is in vertical direction, the legs pointing down.
  • the volute casing so that the outlet opening is arranged in any desired direction in relation to the legs of the volute casing, whereby in an installed pump the legs may be pointing down, and the outlet opening to the desired direction.
  • volute casing for a centrifugal pump the volute casing being very simple of its construction yet capable of performing its task as well as any other much more complicated volute casing.
  • the volute casing of the present invention is less expensive and requires less space than the prior art volute casings, and the vertical forces acting on the volute casing may be taken care of by ordinary legs of the centrifugal pump.
  • the efficiency ratio of the centrifugal pump is optimized with the design of the present invention.
EP16156930.6A 2016-02-23 2016-02-23 Enveloppe à volute pour pompe centrifuge Withdrawn EP3211245A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP16156930.6A EP3211245A1 (fr) 2016-02-23 2016-02-23 Enveloppe à volute pour pompe centrifuge

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP16156930.6A EP3211245A1 (fr) 2016-02-23 2016-02-23 Enveloppe à volute pour pompe centrifuge

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EP3211245A1 true EP3211245A1 (fr) 2017-08-30

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EP16156930.6A Withdrawn EP3211245A1 (fr) 2016-02-23 2016-02-23 Enveloppe à volute pour pompe centrifuge

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108954754A (zh) * 2018-10-24 2018-12-07 奥克斯空调股份有限公司 风道结构及空调器
WO2021090795A1 (fr) * 2019-11-05 2021-05-14 株式会社荏原製作所 Corps de pompe et dispositif de pompe
CN114688086A (zh) * 2020-12-28 2022-07-01 苏州三星电子有限公司 蜗壳和风管机
US20230074178A1 (en) * 2021-09-05 2023-03-09 Unified Brands, Inc. Parallel flow pump

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7217110U (de) * 1973-05-24 Klein Schanzlin & Becker Ag Kreiselpumpengehause
US4844693A (en) * 1984-04-18 1989-07-04 Warman International Ltd. Low-flow pump casing
EP0466167A2 (fr) * 1990-07-12 1992-01-15 A. Ahlstrom Corporation Méthode et dispositif pour pomper un milieu
US5084236A (en) * 1990-10-05 1992-01-28 Westinghouse Electric Corp. Converging spout outlet nozzle on an offset pump casing
WO2013163601A1 (fr) * 2012-04-27 2013-10-31 Weir Minerals Australia, Ltd. Carter de pompe centrifuge à évacuation décalée

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7217110U (de) * 1973-05-24 Klein Schanzlin & Becker Ag Kreiselpumpengehause
US4844693A (en) * 1984-04-18 1989-07-04 Warman International Ltd. Low-flow pump casing
EP0466167A2 (fr) * 1990-07-12 1992-01-15 A. Ahlstrom Corporation Méthode et dispositif pour pomper un milieu
US5084236A (en) * 1990-10-05 1992-01-28 Westinghouse Electric Corp. Converging spout outlet nozzle on an offset pump casing
WO2013163601A1 (fr) * 2012-04-27 2013-10-31 Weir Minerals Australia, Ltd. Carter de pompe centrifuge à évacuation décalée

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108954754A (zh) * 2018-10-24 2018-12-07 奥克斯空调股份有限公司 风道结构及空调器
CN108954754B (zh) * 2018-10-24 2023-09-15 奥克斯空调股份有限公司 风道结构及空调器
WO2021090795A1 (fr) * 2019-11-05 2021-05-14 株式会社荏原製作所 Corps de pompe et dispositif de pompe
JP2021076017A (ja) * 2019-11-05 2021-05-20 株式会社荏原製作所 ポンプケーシングおよびポンプ装置
CN114688086A (zh) * 2020-12-28 2022-07-01 苏州三星电子有限公司 蜗壳和风管机
US20230074178A1 (en) * 2021-09-05 2023-03-09 Unified Brands, Inc. Parallel flow pump

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