Device for a centrifugal pump arrangement

Abstract

The invention relates to a device (1) for a centrifugal pump arrangement (2) for deflecting a radial inflow of medium into an axial flow to the impeller of the centrifugal pump arrangement (2), wherein the device (1) has a base plate (6) and a cover plate (7). According to the invention, the device (1) has a first fluid-guiding element (12) which extends in a radial direction between the base plate (6) and the cover plate (7) and has at least one region (17) which is closed over the full height (19) between the base plate (6) and the cover plate (7), and a region (18) with a recess (15) for evening out a speed distribution of the inflow.

Description

[0001] 10522F

[0002] KSB SE & Co. KGaA 67227 Frankenthal

[0003] Description

[0004] Device for a centrifugal pump arrangement

[0005] The invention relates to a device for a centrifugal pump arrangement for deflecting a radial inflow of medium into an axial flow to the impeller of the centrifugal pump arrangement, wherein the device has a base plate and a cover plate.

[0006] Such devices are used in pumping stations or pumping stations. They are installed upstream of the pumping station pumps, which are typically designed as pipe shaft pumps.

[0007] In coastal areas protected by dikes and located below high tide levels, drainage is essential. Typically, several smaller pumping stations scattered throughout a catchment area supply a larger main pumping station. If the natural outflow through the sluice gate, a closable opening in the dike, is no longer possible due to high water levels, the pumping station's pump activates. A similar operating principle is found in flood control pumping stations on flowing waters.

[0008] In water-scarce regions, irrigation is the dominant method. Often, a main station located on a river or lake supplies several smaller intermediate stations via a system of ditches. The pumps at these stations then pump the water to the fields situated at higher elevations. Due to the low delivery heads, axial pumps with propellers are primarily used. Pumping stations are generally installed vertically, with a trend towards submersible pumps installed in pipe shafts.

[0009] Submersible motor pumps with propellers are also used for general water extraction from standing or flowing, natural or artificial bodies of water, e.g. as main cooling water pumps for power plants or chemical / petrochemical plants.

[0010] EP 1 095 219 B1 describes an inlet structure of covered or open design with one or more semi-axially or axially flowing tube casing pumps arranged therein, wherein a first impeller is arranged at a lowest inlet point, for use in power plants and / or in water management systems, wherein a pump inlet is arranged in an inlet chamber while maintaining a ground clearance. The pump inlet and / or a first impeller of a pump is arranged in a recess, and the recess is arranged in the foundation of the inlet structure.

[0011] EP 0 607 847 B1 discloses a pipe shaft for accommodating a pipe casing pump equipped with an electric motor, comprising a pressure-tight cover serving as the shaft cover and a pressure-tight penetration for one or more lines connected to the electric motor of the pipe casing pump. An opening is arranged at the upper end of the shaft wall, into which the lower, open part of a frame is inserted, while the upper part closing the frame is to be attached separately, with the lines and means enclosing the lines for creating a tight seal being insertable into the open part of the frame.

[0012] DE 103 07 498 A1 relates to a tubular casing pump whose impeller and guide assembly is connected to a riser pipe, wherein a shaft arranged inside the riser pipe, which drives the impeller, is connected to a drive arranged above the riser pipe. A multi-part lantern transmits the weight of the drive to a foundation. An external bearing element, known per se, is provided on the riser pipe and / or the elbow, and the riser pipe opens into a pressure-tight elbow housing. A force-transmitting receptacle, guide, and seal for the external bearing element is provided in a base plate of a pressure-tight elbow housing.

[0013] The inlet chamber is also frequently referred to as a pump sump. It is a collection chamber built directly in front of the centrifugal pump, through which the pumped medium can flow into the pump in a balanced manner from all sides and, ideally, with virtually no turbulence or vortex. This orderly and undisturbed flow is essential for high-speed in-line pumps with propellers or semi-axial impellers, as these react immediately to irregularities and disturbances in the flow. With special inlet chamber designs, damage from cavitation and vibration, as well as losses in pumping capacity or efficiency, can be reduced or avoided compared to an uneven flow. To prevent the formation of so-called air-drawing vortices, sufficiently high water levels must be ensured in the inlet chamber to provide adequate coverage. This usually results in considerable foundation depths for the inlet chamber construction, associated with corresponding costs.The suction of an air-drawing vortex by the pump can lead to significant operational malfunctions and damage to the pump.

[0014] DE 20 2016 101 589 U1 discloses an inlet chamber for an axial pump, consisting of an inlet structure and a flange with a coupling for receiving the axial pump. The inlet structure is designed to absorb the weight of the axial pump and has a base for installation on a building floor.

[0015] In particular, the requirements for inlet structures to ensure adequate inflow and thus safe operation result for 4 10522F

[0016] Conversion projects of existing pumping stations present enormous challenges and difficulties. These often result in extensive excavation work and corresponding costs.

[0017] Even in new buildings, the influence of the specific inlet structure and pump installation on construction costs is significant. Both the extensive construction work required for the inlet chamber and the load transfer via the building's ceiling structure result in enormous material usage and high construction costs.

[0018] The object of the invention is to provide a device for a centrifugal pump that can control the flow in an inlet chamber. The device should also be able to ensure direct load transfer. Furthermore, the device should be characterized by a compact design. The design of the device should facilitate the replacement of spare parts. The device should be simple and cost-effective to manufacture.

[0019] This problem is solved according to the invention by a device for a centrifugal pump arrangement according to the features of claim 1. Preferred variants can be found in the dependent claims, the subclaims, the description and the drawings.

[0020] According to the invention, the device has a first element in the form of a fluid guide element which extends in a radial direction between the base plate and the top plate and has at least one area closed in the full height between the base plate and the top plate and an area with a recess for equalizing the velocity distribution of the flow to the impeller.

[0021] The device is designed, for example, in the form of a radial rectifier. The radial rectifier consists of a circular base plate and a circular top plate, in which there is a centrally arranged circular opening. 5 10522F

[0022] In one embodiment of the invention, the outer diameter of the base and top plates is identical. The diameter of the circular, centrally arranged opening in the top plate essentially corresponds to the suction nozzle diameter of the centrifugal pump.

[0023] The first element, for example, is designed in the form of a central rib. Therefore, the first element extends over the entire diameter of the base or top plate.

[0024] In one variant of the invention, the first element is designed as a plate. The first element is thus a flat, rectangular component made of the same material as the base and top plates.

[0025] For example, the first element is made of the same material thickness as the base and top panels.

[0026] In a preferred embodiment of the invention, the first element is aligned in an axis with a main inflow direction of the conveyed medium.

[0027] The enclosed area comprises, for example, at least one full-height section between the base plate and the top plate. The enclosed area is preferably circular or ring-shaped and extends from the outer edge of the base or top plate to a recess in the first element.

[0028] The area with a recess for equalizing the velocity distribution of the inflow is, for example, located in the center of the device. This area adjoins the closed area directly, so that the area with the recess is located in the center of the device and is surrounded by the closed area.

[0029] For example, the recess is located in the center of the device. 6 10522F

[0030] In one embodiment of the invention, the recess is arranged in the center of the device, with the closed area arranged concentrically around the recess. The closed area extends to the outer edge of the device.

[0031] It has proven advantageous if the closed area extends over more than 10% of the radial extent and less than 40% of the radial extent with respect to the base plate or the cover plate.

[0032] In one embodiment of the invention, the recess is more than 10% and less than 90% of the height between the base plate and the top plate.

[0033] For example, the recess is more than 35% and less than 65% of the height between the base plate and the top plate.

[0034] In one embodiment of the invention, the device includes further elements in the form of fluid guide elements between the base plate and the top plate to form inflow channels. These fluid guide elements have a straightening effect on the flow by reducing any fluid flow discontinuities, such as separation zones, unevenly distributed velocity gradients, etc.

[0035] The base and top plates are connected, for example, by four additional elements in the form of side ribs and by a first element in the form of a central rib. The central rib extends across the entire diameter. In the middle section, the central rib tapers by the size of a rectangular recess.

[0036] In one embodiment of the invention, the device comprises six chambers in the form of inflow spaces, resulting from the arrangement of the additional elements and the first element. Due to the symmetrical arrangement of the elements, all angles of the chambers are identical, so that the inflow can ideally be directed uniformly. 7 10522F

[0037] In an alternative embodiment of the invention, the device comprises at least two further elements and / or fewer than six further elements. In this case, the chamber includes at least four and at most eight chambers in the form of inflow spaces for homogenizing the inflow.

[0038] For example, the first element and the subsequent elements are aligned at the same angle to each other, resulting in a symmetrical structure of the device.

[0039] In a preferred embodiment, the angle of the first element to the other elements and the angle between the other elements are each 60°.

[0040] In principle, all other angular configurations, in particular unequal angular configurations, of the first element to the other elements and between the other elements are also included in this invention.

[0041] Typically, according to the prior art and the recommendations of the Hydraulic Institute Standard, a cone is positioned in the center of an inlet chamber. The inventive design and arrangement of the first element, including the recess of the first element, particularly improves the uniformity of the velocity distribution as well as the suppression or reduction of swirl in the impeller plane. The invention significantly exceeds the limit values ​​of the Hydraulic Institute Standard ANSI / HI 9.8-2018. This means that the maximum velocity deviation from the mean velocity in the considered cross-section (impeller plane) is a maximum of 10% and also exhibits a maximum swirl angle of 5°.

[0042] In one embodiment of the invention, the maximum velocity deviation from the mean velocity in the considered cross-section is less than 6% and has a swash angle of less than 3°. 8 10522F

[0043] The special design of the device, and in particular the advantageous possibility of arranging the fluid guide elements individually or in groups, saves enormous additional effort and costs compared to structures such as inlet chambers with side walls.

[0044] The inventive design of the device eliminates the need for special requirements on pumping stations or pumping stations in general equipped with submersible pumps, with the exception of a low minimum fluid level. Even the minimum fluid level can be significantly lower compared to known submersible pumps in pumping stations or pumping stations in general.

[0045] In one variant, the device features struts for absorbing operational and structural forces and moments. In this version, the device is designed so that the sum of all operational and structural forces and moments from the centrifugal pump and attached piping can be transferred via the device into the base plate of a building.

[0046] In the load-bearing design of the device, i.e., where the device stands on the floor of the pumping station and the centrifugal pump assembly rests on the device, in addition to the struts, the base and cover plates as well as the structural elements are adapted to dissipate the operational and design-related forces and moments.

[0047] In one design variant, the centrifugal pump assembly has an attached support cable or support loop, which makes it possible to raise or lower the centrifugal pump.

[0048] For example, at least one fluid-tight cable entry is provided in the area of ​​the carrying loop. In one embodiment of the invention, the cable can be fixed in a controlled manner via the carrying cable. 9 10522F

[0049] According to the invention, the device for a centrifugal pump arrangement is used in inlet structures of pumping stations and floodwater pumping stations to even out the velocity distribution of the inflow and to reduce the swirl.

[0050] For example, the device for a centrifugal pump arrangement is used in inlet structures of pumping stations and other pumping stations to reduce the base area of ​​the inlet area by eliminating conventional inlet chambers.

[0051] The base and top plates are connected, for example, by four lateral ribs and a central rib. The central rib extends across the entire diameter. In the middle section, the central rib tapers by the size of the rectangular recess.

[0052] In the embodiment of the invention in the form of a non-load-bearing variant, for example, a truncated cone with an angle of inclination of 45° is placed on the central opening of the cover plate. A circular collar plate is, for example, attached around the truncated cone.

[0053] In the load-bearing embodiment of the invention, a cylindrical section with an attached flange is mounted on the cover plate, concentric to the central opening. A truncated cone with a 45° angle of inclination is positioned between the cover plate and the cylindrical section. The flange has a 45° chamfer on its inner diameter, which serves as a seat for the pump. The flange is provided with through-holes to allow for fastening to the pipe shaft.

[0054] To stiffen the structure of the load-bearing version, for example, six support ribs or struts are arranged continuously around the cylinder section. The support ribs are connected to the underside of the flange plate at the top, to the cover plate at the bottom, and to the cylindrical surface at the bottom. 10 10522F

[0055] In one design variant, the struts or support ribs are aligned and fastened in a direct extension or in a planar arrangement to the first element and the other elements on the top plate.

[0056] The contact length and contact area of ​​the struts and the elements with the cover plate are identical. This ensures direct load transfer in the vertical direction.

[0057] The device, in the form of a rectifier, is made, for example, of classic structural steel and fastened to the ground with at least six composite anchors.

[0058] In an alternative design variant, the device is made of stainless steel and connected to the ground via foundation rails.

[0059] The device should ideally be oriented so that the first element, or central rib, is aligned with the direction of flow. The pumped medium flows into the device, for example, across its entire circumference. The four subsequent elements, in the form of straightening ribs, and the full-height outer segments of the first element ensure a smooth flow with regard to velocity distribution and swirl. The top plate, for example, acts as a suction screen, thus allowing for lower water levels on the suction side.

[0060] Since the pumped medium enters the device with varying velocity gradients, an uneven velocity distribution could develop at the pump impeller. Additionally, flow separation zones can occur due to the deflection of the flow from a horizontal to a vertical direction. To counteract this, the first element has a recess. The recess of the first element is arranged to deflect the flow and achieve a more uniform velocity distribution in the impeller plane. The recess of the first 11 10522F

[0061] Elements ensures better momentum exchange, thus achieving a more even velocity distribution. Additionally, the remaining rib of the first element, in direct contact with the base plate, acts as an anti-spin rib.

[0062] To counteract the problem of flow separation zones resulting from flow deflection, the flow deflection is preferably achieved via a 45° incline. This allows the flow of the pumped medium to be directed more closely to the inner wall of the cylinder section. This also results in a more uniform velocity distribution in the impeller plane.

[0063] For example, four further elements in the design serve as side ribs to stabilize the velocity distribution of the flow of the conveyed medium and to reduce the swirl in the inlet of the conveyed medium to the centrifugal pump.

[0064] Due to the advantageous design of the device, particularly with regard to irregularities in the flow, a separate inlet chamber for the centrifugal pump, as is otherwise common in pumping stations, is not required. This allows, for example, centrifugal pumps mounted on the device according to the invention to be installed side by side in pumping stations without partitions.

[0065] In the load-bearing embodiment of the invention, the device is mounted on the floor of an inlet chamber of the pumping station. The pipe shaft, for example, is rigidly connected to the device. The sum of the operational and structural forces and moments originating from the centrifugal pump, the downstream pipe shaft, and the water column can be transferred into the ground via the device.

[0066] The centrifugal pump, for example, rests on a specially designed seat as part of the device, allowing it to be lifted with a support cable. The device remains permanently mounted and requires no additional effort. 12 10522F

[0067] In one variant of the invention, the pipe shaft does not need to be supported by a ceiling structure on site. The majority of the operational and structural forces and moments are transferred into the building foundation via the radial rectifier device. This eliminates the need for a fully load-bearing ceiling structure, thus saving considerable material and financial resources.

[0068] In a non-load-bearing version of the device, in the form of a radial rectifier, it is mounted below the pipe shaft, specifically on the floor of the inlet chamber. The device is not connected to the pipe shaft. The centrifugal pump, for example, is installed inside the pipe shaft. The pipe shaft is preferably suspended from the ceiling structure of the pumping station.

[0069] In this variant of the invention, the hydraulic properties of the device are ideally utilized to achieve favorable flow conditions for the centrifugal pump. The non-load-bearing variant of the device, in the form of a radial rectifier, is advantageously used, for example, in renovation projects where no structural alterations to the existing building are the primary focus, while simultaneously improving the pump hydraulics.

[0070] The device according to the invention offers enormous advantages. For example, the flow conditions of the centrifugal pump are improved, while at the same time the minimum suction-side water level can be reduced compared to an open chamber. The installation of several pumps, each mounted on a device according to the invention, in a pump sump without the need for a special inlet chamber can be achieved. Furthermore, compared to known pump sumps without a mounted device, the installation footprint can be more space-saving. Particularly in new buildings, no load-bearing ceiling structure is required on-site, since the majority of the operational and structural forces and moments can be transferred via the device into the building floor, thereby advantageously reducing overall construction costs.

[0071] Further features and advantages of the invention will become apparent from the description of exemplary embodiments with reference to the drawings and from the drawings themselves.

[0072] This shows:

[0073] Fig. 1 shows a perspective view of a load-bearing device and centrifugal pump.

[0074] Fig. 2 shows a perspective view of a load-bearing device,

[0075] Fig. 3 shows a side view of a load-bearing device,

[0076] Fig. 4 shows a perspective view of a non-load-bearing device and centrifugal pump.

[0077] Fig. 5 shows a schematic representation of a non-load-bearing device,

[0078] Fig. 6 shows a top view of a non-load-bearing device.

[0079] Fig. 1 shows a perspective view of a device 1 for a centrifugal pump assembly 2 for redirecting a radial flow of medium into an axial flow to the impeller of the centrifugal pump assembly 2. The device 1 is designed to support the pump assembly 2 mounted on it. The centrifugal pump assembly 2 is designed as a submersible pump.

[0080] The wet-mounted, single-stage, single-flow submersible pump shown is equipped with an axial propeller (not shown) and is used, for example, in irrigation and drainage pumping stations. 14 10522F

[0081] The centrifugal pump assembly 2 has a carrying loop 3 into which a rope can be attached and which is suitable for raising or lowering the centrifugal pump 2. Simultaneously, the longitudinally watertight potted cable entries 4 are located next to the carrying loop 3.

[0082] The device 1, for diverting a radial flow of medium into an axial flow towards the impeller of the centrifugal pump assembly 2, is mounted on the floor of the pumping station. The pipe shaft (not shown) is rigidly connected to the device 1. The sum of the operational and structural forces and moments originating from the centrifugal pump assembly 2, the downstream pipe shaft, and the water column can be transferred into the floor via the device 1.

[0083] The pipe shaft therefore does not need to be supported by a ceiling structure on site and is arranged on the force-fit support 5. The centrifugal pump assembly 2 is arranged on a self-centering seat. This seat is sealed by an additional O-ring, not shown in Fig. 1, attached to the pump. The suction side of the pump is sealed to the pressure side of the pump to prevent unwanted pressure equalization between the two sides. The O-ring also serves as an anti-rotation device for the pump.

[0084] Fig. 2 shows a perspective view of the load-bearing device 1 without centrifugal pump arrangement and Fig. 3 shows a corresponding side view of the load-bearing device 1 .

[0085] The device 1 is designed in the form of a so-called radial rectifier. The radial rectifier consists of a circular base plate 6 and an annular cover plate 7, in which a centrally arranged, circular opening 8 is located. The outer diameter of the base plate 6 and the cover plate 7 is essentially identical. The diameter of the circular, centrally arranged opening 8 in the cover plate 7 corresponds essentially to the outer diameter of the suction inlet of the centrifugal pump 2.

[0086] The device 1 has struts 9 for better absorption of the forces and moments that occur due to operation and design. For this purpose, six struts 9 in the form of support ribs are arranged continuously around a cylindrical section 10. The struts or support ribs are connected at the top to the underside of a flange plate 11, at the bottom to the cover plate 7 and to the outer surface of the cylindrical section 10.

[0087] The struts 9 are mounted on the cover plate 7, in direct extension or in a planar arrangement with a first fluid guide element 12 and several second fluid guide elements 13, and are aligned and fastened. The contact length and contact area of ​​both the struts 9 and the elements 12, 13 with the cover plate 7 are identical. This ensures direct load transfer in the vertical direction. The first fluid guide element 12 and the second fluid guide elements 13 are arranged between the cover plate 7 and the base plate 6.

[0088] The struts 9 absorb the operational and structural forces and moments of the centrifugal pump arrangement 2 and the pipe shaft via the flange plate 11 and transfer them via the cover plate 7, the first element 12 and the second elements 13 to the base plate 6 in the ground of the structure.

[0089] The cylinder section 10 with the attached flange 11 is arranged concentrically to the opening 8 on the cover plate 7. The diameter of the opening 8 corresponds essentially to the inner diameter of the cylinder section 10. The flange 11 has a 45° chamfer on its inner diameter, which serves as a seat for the centrifugal pump assembly 2. The flange 11 is provided with through-holes 14 to allow attachment to the pipe shaft (not shown).

[0090] As shown in Fig. 3, the first element 12 is designed in the form of a central rib. In this respect, the first element 12 extends over the entire diameter of the base plate 6 or cover plate 7 and is plate-like. The first element 12 is a flat, rectangular component made of the same material as the base plate 6 and cover plate 7. The first element 12 is aligned with a 16 10522F

[0091] The main flow direction of the conveyed medium is aligned. The first fluid guiding element 12 has a recess 15 that extends essentially over the entire diameter of the opening 8.

[0092] The first element 12 and the second elements 13 are arranged at an angle of essentially 60°, thereby creating identical and symmetrically arranged inflow spaces 16 or inlet chambers. The device 1 has an essentially symmetrical structure.

[0093] The device 1 is made of structural steel and has a wall thickness of 15 mm in the illustrated version DN700.

[0094] A ring-shaped, closed section 17 extends from the outer edge of the base plate 6 or the cover plate 7 to the recess 15 of the first element 12. This closed section 17 comprises essentially 45% of the radial extent of the first element 12. The recess 15 serves to ensure a uniform velocity distribution and to reduce the swirl of the inflow at the center of the device 1. The open section 18 is designed as a circular opening that extends cylindrically into the device 1 and is located in front of the suction inlet of the centrifugal pump. The open section 18 extends essentially over the entire diameter of the opening 8. The section 17 enclosed by the cover plate 7 encompasses a portion of the first fluid guide element 12 at its full height 19 between the base plate 6 and the cover plate 7.

[0095] Fig. 4 shows a perspective view of a non-load-bearing device 1 and a centrifugal pump assembly 2. This corresponds essentially to the representation in Fig. 1, but without the struts 9 and the cylinder section 10; however, a circular collar plate 20 is attached to the cover plate 7.

[0096] An advantageous embodiment of a non-load-bearing device 1 for a centrifugal pump arrangement 2 for deflecting a radial inflow of medium into an axial flow to the impeller of a centrifugal pump is shown in Figs. 5 and 6, 17 10522F, which are described together below. Fig. 5 reveals a schematic representation of the non-load-bearing device 1, while Fig. 6 shows a top view of the non-load-bearing device 1.

[0097] The first fluid guide element 12 is designed as a central rib or anti-swirl rib and prevents rotation of the pumped medium in front of the suction nozzle. The first fluid guide element 12 has an upper edge 21 with a recess 15. The recess 15 of the first fluid guide element 12 facilitates velocity and momentum compensation of the pumped medium. The cover plate 7 also acts as a suction shield for the intake centrifugal pump 2.

[0098] The device 1 has four secondary fluid guide elements 13 between the base plate 6 and the top plate 7 to form inflow chambers 16. The first element 12 and the secondary elements 13 are arranged at an angle of essentially 60°, thereby creating identical and symmetrically arranged inflow chambers 16. The device 1 has a substantially symmetrical design.

[0099] In each inflow chamber 16, the base plate 6 is fixed to the base of the structure by at least two composite anchors (not shown). Alternatively, it can be fastened to the base using foundation rails embedded in the ground.

[0100] The base plate 6 and the top plate 7 are connected via the four second elements 13 in the form of side ribs and via the first element 12 in the form of a central rib. The central rib extends over the entire diameter of the base plate 6. In the central area, the first element 12 is reduced by the size of a recess 15 in the shape of a rectangle.

[0101] The area 17 enclosed by the cover plate 7 comprises a section of the first fluid guide element 12 at its full height 19 between the base plate 6 and the cover plate 7. The enclosed area 17 is annular and extends from the outer edge of the base plate 6 or cover plate 7 to the recess 15 of the first element 12. The enclosed area 17 extends over 40% of the radial extent of the first element 12.

[0102] The four second fluid guide elements 13 together with fluid guide element 12 stabilize the velocity distribution of the flow of the pumped medium and reduce the swirl in the inlet of the pumped medium to the centrifugal pump 2. This allows, for example, centrifugal pump arrangements 2 to be installed side by side in pumping stations or pumping stations without partitions.

[0103] The recess 15 is arranged in the center of the device 1 to even out the velocity distribution and reduce the swirl of the inflow. This area adjoins the closed area 17 and is designated with the reference numeral 18. Area 18 is designed as a circular opening that extends cylindrically into the device 1 and is located in front of the suction inlet of the centrifugal pump.

[0104] The recess 15 is arranged in the center of the device 1 and the height of the recess 15 in the illustrated embodiment is 50% of the height between the base plate 6 and the top plate 7.

[0105] Device 1 is a welded construction, manufactured, for example, from structural steel. Versions in corrosion-resistant stainless steel are also possible. The respective wall thicknesses can vary depending on the material and conveyed medium, as well as the specific load regime. In principle, the device can also be implemented as a bolted construction.

Claims

19 10522F Patent claims Device for a centrifugal pump arrangement 1. Device (1) for a centrifugal pump arrangement (2) for deflecting a radial inflow of medium into an axial flow to the impeller of the centrifugal pump arrangement (2), wherein the device (1) has a base plate (6) and a cover plate (7), characterized in that the device (1) has a first fluid guide element (12) which extends in a radial direction between the base plate (6) and the cover plate (7) and has at least one area (17) closed at its full height (19) between the base plate (6) and the cover plate (7) and an area (18) with a recess (15) for equalizing a velocity distribution of the inflow.

2. Device according to claim 1, characterized in that the first element (12) is aligned in an axis with a main inflow direction of the medium.

3. Device according to claim 1 or 2, characterized in that the first element (12) is designed in a plate-like form.

4. Device according to one of claims 1 to 3, characterized in that the closed area (17) extends over more than 10% of the radial extent and less than 40% of the radial extent.

5. Device according to one of claims 1 to 4, characterized in that the recess (15) is more than 10% of the height (19) and less than 90% of the height (19). 20 10522F 6. Device according to one of claims 1 to 5, characterized in that the device (1 ) has further elements (13) between the base plate (6) and the top plate (7) for forming inflow spaces (16).

7. Device according to claim 6, characterized in that the device (1 ) has at least two second elements (13) and / or has fewer than six second elements (13).

8. Device according to claim 6 or 7, characterized in that the first element (12) and the second elements (13) are aligned at the same angle (a) to each other.

9. Device according to one of claims 1 to 8, characterized in that the device (1) has struts (9) for absorbing the forces and moments occurring due to operation and design.

10. Use of a device (1 ) for a centrifugal pump arrangement (2) particularly in inlet structures of pumping stations and other pumping stations for equalizing a velocity distribution of the inflow, while simultaneously reducing the swirl and thereby lowering the required minimum water level on the inlet side.

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