WO2016151528A1 - Pompe centrifuge à étages multiples - Google Patents

Pompe centrifuge à étages multiples Download PDF

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Publication number
WO2016151528A1
WO2016151528A1 PCT/IB2016/051685 IB2016051685W WO2016151528A1 WO 2016151528 A1 WO2016151528 A1 WO 2016151528A1 IB 2016051685 W IB2016051685 W IB 2016051685W WO 2016151528 A1 WO2016151528 A1 WO 2016151528A1
Authority
WO
WIPO (PCT)
Prior art keywords
impeller
hub
cover
centrifugal pump
pump
Prior art date
Application number
PCT/IB2016/051685
Other languages
English (en)
Inventor
Fausto Fumagalli
Original Assignee
Exa Pumps S.R.L.
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 Exa Pumps S.R.L. filed Critical Exa Pumps S.R.L.
Priority to ES16720894T priority Critical patent/ES2924730T3/es
Priority to EP16720894.1A priority patent/EP3274587B1/fr
Publication of WO2016151528A1 publication Critical patent/WO2016151528A1/fr

Links

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
    • F04D1/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
    • F04D1/06—Multi-stage 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
    • F04D13/00—Pumping installations or systems
    • F04D13/02—Units comprising pumps and their driving means
    • F04D13/06—Units comprising pumps and their driving means the pump being electrically driven
    • F04D13/08—Units comprising pumps and their driving means the pump being electrically driven for submerged use
    • F04D13/086—Units comprising pumps and their driving means the pump being electrically driven for submerged use the pump and drive motor are both submerged
    • 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
    • F04D29/08—Sealings
    • F04D29/16—Sealings between pressure and suction sides
    • F04D29/165—Sealings between pressure and suction sides especially adapted for liquid pumps
    • F04D29/167—Sealings between pressure and suction sides especially adapted for liquid pumps of a centrifugal flow wheel

Definitions

  • the present invention relates to a submersible centrifugal pump of the multistage type, used for extracting fluids.
  • Multistage centrifugal pumps are devices, for example enclosed in a cylindrical housing having the length as predominant dimension, wherein a plurality of stages are present and arranged one downstream of the other, through which a fluid, usually water, is gradually subjected to a pressure increase thanks to the impellers shaped so as to apply on the fluid itself a centrifugal action and thanks to special diffusers.
  • a fluid usually water
  • each single stage of this type of pumps is constituted by a chamber housing a usually disc-shaped impeller, and a diffuser allowing the fluid to flow from one stage to the next.
  • the chamber is provided with a central hole coaxial with the impeller, in which the drive shaft passes through for transmitting rotary motion to the impeller and is suitably insulated from the fluid.
  • the impeller by rotating inside the chamber, transmits a centrifugal acceleration to the fluid, from its center to the periphery, thereby accelerating it towards a peripheral area of the chamber and driving it to the next stage by means of the aforesaid diffuser.
  • the fluid drawn from the preceding (upstream) stage is then pumped to the next (downstream) one through the central hole of each chamber, where there is also the drive shaft shared by all the impellers.
  • An electric motor typically placed upstream of the stages with respect to the extraction fluid flow, rotates the drive shaft.
  • this kind of pumps have clearances both in axial and in radial directions with respect to the axis of the pump, between the impeller and the respective chamber.
  • the radial clearances are intended to compensate for possible changes in the offset between the impeller and the chamber caused by possible misalignments, so as to prevent consequently the facing circular edges of the impeller itself from interfering with the side walls of the chamber.
  • the axial clearances are intended to limit damaging frictions between the parts moving relative to each other which would result in the jamming of the impeller. These clearances are even more necessary in those pumps designed to be submerged in underground wells for the extraction of fluids, particularly water, containing sand, earth and/or small debris that may accelerate the wear of the relative-moving parts and cause them to jam.
  • the prior art pumps are provided with special gaskets fitted in each stage between the bottom of the chamber and the impeller so as to maximize the fluid flow between the lower hole of the chamber and the diffuser.
  • This solution has the drawback of limiting the radial clearance of the impeller with respect to the chamber, thereby causing sand and debris to accumulate between the gaskets which, being subject to accelerated wear, are no longer able to carry out their task after the pump has operated for a certain period.
  • a further problem with the multistage pumps of the known art occurs when there is no fluid to be extracted. In fact, in the latter case, there is no fluid lubricating the parts moving relative to each other so that the friction between the gaskets can cause the full jamming of the pump.
  • the present invention achieves these and other objects by means of a submersible centrifugal pump of the multistage type according to claim 1 and the related dependent claims.
  • each pump stages comprises a stationary-vane diffuser and a cover which are separated from one another by a cylindrical spacer, and an impeller placed between said cover and said diffuser, as well as supporting and sealing means to support and seal the impeller to the cover and/or the diffuser of an upstream stage.
  • Upstream stage means herein the preceding stage with respect to the extraction flow of the pump.
  • the supporting and sealing means comprise a central supporting element for the impeller hub.
  • This central supporting element preferably, but not exclusively, comprises a bushing for supporting and sealing the hub with a central seat of the diffuser of the upstream stage.
  • the supporting and sealing means further comprise a rib jutting from the cover and/or the diffuser of the upstream stage so that the impeller is consequently supported at least in one surface region thereof far from the central hub during the operation of the pump.
  • the supporting and sealing means of the impeller provide a central supporting element for the impeller hub as well as a rib for supporting a surface region of the impeller, wherein this rib is separate from the afore said central supporting element of the impeller hub and, substantially, is radially far away from such a central supporting element of the hub, i.e. not coincident therewith.
  • the bushing or anyway the above said central supporting element for the impeller hub, is provided with a compensating surface or body preferably subject to wear or anyway able to be plastically shaped, adapted to be shaped after the pump has been operating for a period and which initially keeps the propeller away from said rib and then, after being worn, allows the impeller to gradually approach and consequently be supported by the rib itself. Therefore, after the pump has been operating for a period (typically some hours), the impeller rests on two different supporting portions radially separated from one another.
  • the axial load is more evenly distributed with respect to the pumps of the prior art.
  • the second support is obtained by approaching the impeller to the cover. During the approach the axis of the impeller is kept centered, therefore the shaping of the compensating surface of the bushing allows the impeller to be properly supported even if there are deviations from the expected theoretical tolerances.
  • the pump object of the present Patent right can also have a dry running, i.e. temporarily without pumped fluids.
  • a dry running i.e. temporarily without pumped fluids.
  • the impeller is able to rotate resting on the cover and/or the diffuser of an upstream stage.
  • the impeller is made of polyamide, preferably nylon 6.6 having a low coefficient of friction and a very high softening point (180°C - 200°C).
  • this latter characteristic allows the pump according to the present invention to extract high temperature fluids (e.g. boiling water).
  • the impeller comprises a protecting portion jutting towards the cover.
  • This protecting portion is arranged around the impeller inlet and acts as a "barrier” in order to slow down and limit the infiltration of sand and/or debris between the impeller and the cover.
  • the central supporting element comprises a ceramic ring positioned under the bushing. If the impeller wears, for example due to the sand in the extracted fluid, the hub becomes more supported by the ceramic ring thereby distributing the axial load of the impeller on an additional support. This characteristic allows the correct operation of the pump even if the impeller has been worn due to friction with the rib jutting from the cover, thereby obtaining a more reliable and durable pump compared to known art pumps.
  • FIG. 1 is a longitudinal sectional view of an embodiment of the multistage pump according to the present invention.
  • FIG. 2 is a longitudinal sectional view of an embodiment of two stages of the multistage pump according to the present invention
  • figure 3 is a sectional exploded view of supporting and sealing means of the embodiment shown in figure 2;
  • - figure 4 is a longitudinal section of an enlarged detail of the supporting and sealing means during a first operating period of the pump according to the present invention
  • - figure 5 is a longitudinal section of an enlarged detail of the supporting and sealing means during a second operating period of the pump according to the present invention
  • FIG. 6 is a longitudinal section of an enlarged detail of the supporting and sealing means during a third operating period of the pump according to the present invention.
  • reference 1 shows a multistage centrifugal pump according to an embodiment of the present invention, comprising an outer jacket 2, generally made of stainless steel, mounted on the casing of an electric motor 3, and a plurality of stages 4.
  • the electric motor 3 is supplied through cables conveniently protected by a "slab" 5 against possible abrasions during the installation of the pump 1.
  • the electric motor transmits the rotary motion to the impellers of each stage through a shaft 10 substantially coaxial with the axis of the pump 1.
  • the fluid is drawn through a suction port 6 substantially positioned at one end of the outer jacket 2 and provided with a filter 7 to prevent debris larger than those tolerated from infiltrating, and is passed through several pumping stages 4 up to a valve 8 positioned near the delivery outlet 9 positioned at the other end of the jacket 2.
  • Figure 2 shows elements belonging to two general stages 4 of the pump 1 in which the stage 4a is upstream of the stage 4b, i.e. the fluid first flows through the stage 4a and then is put into the stage 4b.
  • the stage 4b comprises a stationary- vanes diffuser 13b and a cover 11 which are separated from one another by a cylindrical spacer 12 so as to form a chamber.
  • the diffuser 13b and the cover 11 are fixed on the spacer 12 by a pressure fit.
  • the cover 11 of the downstream stage can be permanently coupled to the diffuser 13a of the upstream stage, e.g. by juxtaposing geometrically complementary parts (by interlocking complementary shapes) or by mechanical constraints.
  • the cover of the upstream stage can be made in one piece with the diffuser of the downstream stage, that is, the diffuser may comprise a top portion acting as a cover for the next stage.
  • a substantially disc-shaped impeller 14 i.e. cylindrical with a circular base and a limited height, and for example of the closed type, is located inside the chamber formed between the cover 11 and the diffuser 13b.
  • the impeller 14 is provided with a central hub 17 having the drive shaft 10 for transmitting rotary motion constrained thereto, a central fluid inlet 22 substantially arranged around the hub 17, as well as with a plurality of perimeter outflow ports, connected to the central inlet 22, the accelerated fluid being able to exit therefrom due to centrifugal force which is subject to.
  • the cover 11 and the diffuser 13b have a central opening for allowing the fluid to flow in the direction shown by the arrows, and the shaft 10 to pass therethrough for transmitting the rotary motion to the impeller 14.
  • impeller 14 shown in figures is of the closed type, further embodiments can provide impellers 14 of the half-open type being still within the protection scope of the present invention.
  • Each stage 4b is provided with supporting and sealing means 16 to support and seal the impeller 14 to the cover 11 and/or the diffuser 13a of an upstream stage 4a.
  • These supporting and sealing means 16 comprise a central supporting element 18 to support and seal the hub 17 of the impeller 14 and a rib 15 jutting from the cover 11 in order to support from below the impeller itself 14 at least in a surface area thereof far from the central hub 17 during the pump operation.
  • the rib 15 may jut from the diffuser 13a of the upstream stage 4a, for example in the case where the diffuser 13a and the cover 11 are made in one piece.
  • the cover 11 is fastened to the diffuser 13a of an upstream stage 4a by mechanical or interlocking retainers.
  • the rib 15 is arranged around the opening 20 of the cover 11 and preferably has a rounded profile jutting towards the impeller 14, so that the resulting support of the impeller 14 on the rib 15 takes place at a contact surface free from sharp edges.
  • the rib has a circular shape, and its center line passes through the longitudinal axis of the pump 1 which is coincident with the axis of rotation of the impellers.
  • This rib 15 is placed far away from the central supporting element 18 for the hub 17 of the impeller 14, or at least not coincident therewith, thereby potentially allowing the impeller 14 itself to be supported at a surface region thereof that is far away from, or at least not coincident with, the respective central hub 17.
  • the central supporting element 18 comprises a bushing 18a for supporting and sealing the hub 17 with a central seat 19 of the diffuser 13a of the upstream stage 4a.
  • the bushing is mounted in the central seat 19 of the diffuser 13a of the upstream stage 4a (as shown in figure 1) so as to cover the edge of the seat 19.
  • the hub 17 of the impeller has a stepped profile and is sized so that the outer portion 17a of the hub rests on the bushing 18a and the inner portion 17b of the hub can fit inside the seat 19 of the diffuser.
  • the bushing 18a is made of plastic material, preferably acetal resin (POM-C), and is provided with a compensating surface 21 preferably subject to wear or anyway able to be plastically (i.e. permanently) shaped and adapted to shape after the pump has been operating for a period so as to allow the impeller 14 to approach and consequently rest on the rib 15.
  • POM-C acetal resin
  • this compensating surface 21 might be substituted for a compensating body that is anyway shaped and performs the afore said function of being shaped so as to allow the impeller 14 to approach and be supported by the rib 15 after a certain number of operating cycles of the pump.
  • the compensating surface 21 interfaces between the bushing and the hub 17 of the impeller 14.
  • the compensating surface 21 is shaped due to the friction between the bushing 18a and the hub 17.
  • the impeller is only coupled with the diffuser 13a of the upstream stage 4a at the compensating surface 21, i.e. the bushing portion covering the edge of the seat 19 of the diffuser 13a.
  • This support is designed so as to close the pressure recirculation between the impeller 14 and the previous one (the upstream one).
  • the hub 17 supported by the bushing 18a By rotating, the hub 17 supported by the bushing 18a, causes a friction increasingly wearing out, or anyway shaping, the bushing along the compensating surface 21, thereby reducing its height. As the bushing get smaller, the impeller 14 gradually approaches the cover 11 until the impeller is supported on the rib 15 in at least one surface area 14a of the impeller that is far from the hub.
  • the bushing 18a is shaped by the hub 17 of the impeller 14 thereby compensating for possible manufacturing defects and tolerances between the impeller and the cover.
  • the impeller is further coupled to the cover 11 at the rib 15, as shown in Figure 5.
  • bushing 18a is supposed to be made of a plastic material, any other material known in the art and suitable for the purpose can be used instead.
  • the bushing 18a has been described in which the latter wears due to the material it is made of and after a certain operating period, thereby decreasing in height and thus allowing the lower surface of the impeller 14 to be supported by the rib 15, alternatives are possible in which the bush 18a is already sized so as to allow the impeller 14 to be supported by the rib 15, as afore said, and is made of a hard wearing material.
  • This characteristic allows this supporting and sealing means 16 to be made so as to have reduced contact surfaces in order to minimize the friction between the parts moving relative to each other and allow also the dry running of the pump, at least for a certain operating period without seizing.
  • the impeller 14 can be preferably made of polyamide, more preferably of nylon 6.6 that, by having a very high softening point (180°C - 200°C), allows the pump to extract also high temperature fluids (e.g. boiling water). Additional embodiments may include the use of different polymeric materials, for example plastic materials having low friction coefficient or high softening point, still remaining within the protection scope of the present invention.
  • the cover 11 is preferably totally made of stainless steel, although additional embodiments can be provided wherein the cover 11 can be made of other materials different from steel and the rib 15 can be attached to the cover by means that are known per se in the art (welding, gluing, etc.).
  • the impeller 14 can wear due, for example, to the abrasive action of sand and small debris which can infiltrate between the cover 11 and the impeller 14, especially near the rib 15.
  • the central supporting element 18 can further comprise a ceramic ring 18b positioned between the diffuser seat 19 of the upstream stage and the bushing 18a.
  • the stepped shape of the hub 17 can allow the outer portion 17a of the hub to rest on the bushing 18a and the inner portion 17b of the hub to rest on the ceramic ring 18b. Therefore, during an extended operating period of the pump, the inner portion 17b of the hub 17 can become rested on the ceramic ring 18b thereby stopping the approach of the impeller
  • the impeller 14 rests on three separate areas coaxial with each other.
  • the outer part 17a of the hub 17 rests on the bushing 18a (at the compensating surface 21)
  • the inner part 17b of the hub rests on the ceramic ring 18b
  • the surface area 14a of the impeller rests on the rib 15.
  • the impeller 14 comprises a protecting portion 23 jutting towards the cover 11, i.e. a frame arranged around the inlet 22.
  • the protecting portion 23 is arranged at the edge of the inlet 22.
  • the inlet 22, the opening 20 of the cover 11 , the rib 15 and the protecting portion 23 have a circular shape, all concentric with respect to the longitudinal axis of the pump.
  • the protecting portion 23, or frame has a diameter smaller than the rib
  • Additional embodiments may provide that the portion 23 is implemented on the cover 11 or the diffuser 13a of the upstream stage 4a jutting towards the impeller 14, preferably so as to allow this portion 23 to be at least partially housed within the inlet 22 of the impeller 14.
  • the protective portion 23, acting as a "barrier" for any infiltration of sand and/or debris between the impeller and the cover, further increases the operating time of the pump, causing it to be more durable than those of prior art.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

L'invention concerne une pompe centrifuge submersible (1) pour extraire des fluides, du type à étages multiples, dans laquelle pompe chacun desdits étages (4, 4b) comprend un diffuseur à aubes fixes (13b) et un capot (11) qui sont séparés l'un de l'autre par un élément d'espacement cylindrique (12), et une hélice (14) disposée entre ledit capot (11) et ledit diffuseur (13b) et comportant un moyeu central (17) ayant un arbre d'entraînement (10) pour transmettre un mouvement rotatif limité à cette dernière, ainsi que des moyens de soutien et d'étanchéité (16) pour supporter et rendre étanche l'hélice (14) vis-à-vis du capot (11) et/ou du diffuseur (13a) d'un étage amont (4a), et laquelle est caractérisée en ce que lesdits moyens de support et d'étanchéité (16) comprennent un élément de support central (18) pour le moyeu (17) de ladite hélice (14) et une nervure (15) faisant saillie à partir dudit capot (11) et/ou diffuseur (13a) de l'étage amont (13a), de telle sorte que l'hélice (14) est, par conséquent, supportée au moins dans une région de surface (14a) de cette dernière éloignée dudit moyeu central (17) pendant le fonctionnement de la pompe (1).
PCT/IB2016/051685 2015-03-25 2016-03-24 Pompe centrifuge à étages multiples WO2016151528A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
ES16720894T ES2924730T3 (es) 2015-03-25 2016-03-24 Bomba centrífuga multietapa
EP16720894.1A EP3274587B1 (fr) 2015-03-25 2016-03-24 Pompe centrifuge a etages multiples

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP15160856.9 2015-03-25
EP15160856 2015-03-25

Publications (1)

Publication Number Publication Date
WO2016151528A1 true WO2016151528A1 (fr) 2016-09-29

Family

ID=53189566

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2016/051685 WO2016151528A1 (fr) 2015-03-25 2016-03-24 Pompe centrifuge à étages multiples

Country Status (4)

Country Link
EP (1) EP3274587B1 (fr)
ES (1) ES2924730T3 (fr)
MA (1) MA41819A (fr)
WO (1) WO2016151528A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3265001A (en) * 1964-04-24 1966-08-09 Red Jacket Mfg Company Centrifugal pump
US3477384A (en) * 1968-01-04 1969-11-11 Dempster Ind Inc Submersible multi-stage diffuser type pump
EP0554803A1 (fr) * 1992-02-07 1993-08-11 F.EL.SOM. S.r.l. Pompe centrifuge multiétages
DE19800617A1 (de) * 1998-01-12 1999-07-15 Klein Schanzlin & Becker Ag Kreiselpumpe
US20060269404A1 (en) * 2005-05-26 2006-11-30 Franklin Electric Co., Inc. Multistage pump

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3265001A (en) * 1964-04-24 1966-08-09 Red Jacket Mfg Company Centrifugal pump
US3477384A (en) * 1968-01-04 1969-11-11 Dempster Ind Inc Submersible multi-stage diffuser type pump
EP0554803A1 (fr) * 1992-02-07 1993-08-11 F.EL.SOM. S.r.l. Pompe centrifuge multiétages
DE19800617A1 (de) * 1998-01-12 1999-07-15 Klein Schanzlin & Becker Ag Kreiselpumpe
US20060269404A1 (en) * 2005-05-26 2006-11-30 Franklin Electric Co., Inc. Multistage pump

Also Published As

Publication number Publication date
EP3274587A1 (fr) 2018-01-31
MA41819A (fr) 2021-03-17
EP3274587B1 (fr) 2022-05-04
ES2924730T3 (es) 2022-10-10

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