WO2024022777A1

WO2024022777A1 - Pump assembly

Info

Publication number: WO2024022777A1
Application number: PCT/EP2023/068714
Authority: WO
Inventors: Julien Blaise; Uwe Bruhns; Armin Gaiser; Ralf Graber; Richard Maiwald; Sven Oberholz
Original assignee: KSB SE & Co. KGaA
Priority date: 2022-07-25
Filing date: 2023-07-06
Publication date: 2024-02-01
Also published as: DE102022118510A1

Abstract

The invention relates to a pump assembly (1), in particular a centrifugal pump assembly, comprising: a hydraulic housing (2); a suction port (5) which is formed on the hydraulic housing (2) and has an inlet opening (6); a pressure port (7) which is formed on the hydraulic housing (2) and has an outlet opening (8); a flow chamber (11) which is at least partly delimited by the hydraulic housing (2); a housing cover (3) which closes the hydraulic housing (2); an impeller (14) which is disposed in the flow chamber (11) and can be driven about an axis of rotation (A) by means of a shaft (9); and an inflow nozzle (17) which has a first end (16) connected indirectly or directly to the hydraulic housing (2), and a substantially cylindrical portion (18) which extends coaxially to the axis of rotation (A) toward the inlet opening (6); wherein a second, free end (19) opposite the first end (16) is disposed in a recess (20) of the inlet opening (6) at the transition from the inlet opening (6) to the flow chamber (11), and a radial ring gap (21) is created between the portion (18) of the inflow nozzle (17) and the hydraulic housing (2) in the region of the recess (20). According to the invention, the portion (18) is divided into a first sub-portion (22) and a second sub-portion (23) which is close to the free end (19), and in the region of the free end (19) the second sub-portion (23) comprises a sleeve- or ring-type expansion element (24), the material of the expansion element (24) having a higher coefficient of thermal expansion than the material of the hydraulic housing (2).

Description

KSB SE & Co. KGaA 67227 Frankenthal

Description

Pump arrangement

The invention relates to a pump arrangement, in particular a centrifugal pump arrangement, with a hydraulic housing, a suction port formed on the hydraulic housing with an inlet opening, a pressure port formed on the hydraulic housing with an outlet opening, a flow chamber at least partially delimited by the hydraulic housing, a housing cover closing the hydraulic housing, a housing cover in the Flow chamber arranged impeller which can be driven via a shaft about an axis of rotation and an inlet nozzle with a first end connected directly or indirectly to the hydraulic housing and a substantially cylindrical section which extends coaxially to the axis of rotation in the direction of the inlet opening, with a second, opposite the first end, free end is arranged at the transition from the inlet opening to the flow chamber in a recess of the inlet opening and a radial annular gap is created in the area of the recess between the section of the inlet nozzle and the hydraulic housing.

Such pump arrangements are used, for example, in nuclear main coolant pumps.

The free end of the inlet nozzle and the hydraulic housing form an annular gap that connects the high-pressure and low-pressure areas of the pump. Due to the pressure difference between the high and low pressure areas, a volume flow occurs through this gap, which leads to volumetric losses and thus to reduced pump efficiency. These volumetric losses are dependent

REPLACEMENT SHEET (RULE 26) on the pressure difference and the gap width between the housing and the inlet nozzle. In order to enable the assembly of the inlet nozzle, a certain radial annular gap between these two parts is unavoidable. In addition, the gap is increased during hot operation due to the expansion of the hydraulic housing due to internal pressure and temperature. This leads to increased volumetric losses through this gap in hot operation and thus to reduced efficiency. The aim of the present invention is to minimize the annular gap, in particular the radial gap width, in hot operation and thus reduce the volumetric losses and increase the efficiency of the pump. This takes into account the fact that a certain gap at ambient temperature is still required for assembly reasons.

The present invention is based on the object of mitigating or even completely eliminating the shortcomings of the devices known from the prior art. Specifically, it is an object of the present invention to provide a pump arrangement in which the increase in the gap due to pressure and temperature during hot operation of the pump is reduced and the efficiency of the pump is increased.

This object is achieved by a pump arrangement with the feature of claim 1, according to which the cylindrical section is divided into a first section and a second section near the free end and in the area of the free end the second section comprises a sleeve or ring-like expansion element, whereby the material of the expansion element has a higher thermal expansion coefficient than the material of the hydraulic housing.

In order to safely reduce or completely close the annular gap, it has proven to be particularly advantageous if the material of the expansion element comprises austenitic steel. The austenitic material has a high coefficient of expansion and at the same time good resistance to the pumped medium.

A simple and operationally reliable embodiment can be obtained by welding the expansion element and the first section together are, wherein the material of the expansion element has a higher coefficient of expansion than the hydraulic housing.

So that an exact alignment of the first section with the second section is possible without a significant step during operation and the inner surface of the expansion element and the inner surface of the first section are essentially in alignment in a flow-efficient manner, the expansion element preferably has a contact surface facing the first section, which includes an axial annular elevation and an axial recess.

For this purpose, the first section has a contact surface directed towards the expansion element, which is at least partially designed to be complementary to the contact surface of the expansion element.

In an alternative embodiment, the second section close to the free end in the area of the free end comprises the sleeve- or ring-like expansion element and a holding device that at least partially surrounds the expansion element.

Advantageously, for an operationally reliable structure, the holding device is designed in one piece with the first section and the expansion element is arranged in the holding device.

The material of the holding device advantageously has a lower expansion coefficient than the material of the sleeve- or ring-like expansion element. As a result, the holding device is stretched outwards via the sleeve- or ring-like expansion element at higher temperatures due to the higher expansion coefficient of the sleeve- or ring-like expansion element and thus the gap to the hydraulic housing is reduced or closed.

For easy assembly and safe operation, the expansion element and the holding device are connected to one another using a shrink fit. The use of a welding process can therefore be dispensed with. So that the radial annular gap can be securely closed during hot operation, the holding device advantageously has an area with an enlarged inner diameter, such that the holding device has flexibility in the radial direction.

Further advantages, features and effects of the present invention emerge from the figures below. Show here

1 shows a longitudinal section through a pump arrangement with an inlet nozzle according to the prior art,

2 shows a longitudinal section through a first embodiment of the inlet nozzle according to the invention,

Fig. 3 shows a longitudinal section through a second embodiment of the inlet nozzle according to the invention.

1 shows a pump arrangement 1 in the form of a main coolant pump arrangement according to the prior art. The pump arrangement 1 has a housing part designed as a hydraulic housing 2, a housing cover 3 and a lantern 4.

The hydraulic housing 2 has an inlet opening 6 on a suction port 5 for sucking in a pumped medium and an outlet opening 8 on a pressure port 7 for ejecting the pumped medium. The housing cover 3 is arranged on the side of the hydraulic housing 2 opposite the inlet opening 6. The lantern 4 is attached to the side of the housing cover 3 facing away from the hydraulic housing 2. A motor, not shown, is connected to the hydraulic housing 2 by means of the lantern.

A shaft 9, which can be rotated about an axis of rotation A and is designed in several parts in the embodiment shown as an example, extends from the motor, not shown, through an opening 10 provided in the housing cover 3 into a flow chamber 11 delimited by the hydraulic housing 2 and the housing cover 3. A bearing device (not shown) for supporting the shaft 9 is provided in the opening 10. The flow chamber 11 is sealed against leakage into the lantern 4 with a sealing package 12, which comprises several sealing devices arranged one behind the other in the axial direction.

An impeller 14 is attached to an end 13 of the shaft 9 located within the flow chamber 11. In the exemplary embodiment, on the side opposite the suction port 5 or the inlet opening 6, a stator 15 surrounding the impeller 14 is arranged or attached to the hydraulic housing 2 in a rotationally fixed manner and cannot be displaced in the axial direction. The stator 15 ensures that the swirl flow emerging from the impeller 14 is diverted into a swirl-free flow with as little loss as possible, whereby the magnitude of the absolute speed is reduced and the static pressure is increased.

An inlet nozzle 17 is attached to the stator 15 with a first end 16. The inlet nozzle 17 has a substantially cylindrical section 18 which extends coaxially to the axis of rotation A in the direction of the inlet opening 6. A second, free end 19, opposite the first end 16, is arranged at the transition from the inlet opening 6 to the flow chamber 11 in a recess 20 of the inlet opening 6, i.e. an area with an enlarged inner diameter. In the area of the enlarged inner diameter, a radial annular gap 21 is created between the section 18 near the area of the free end 19 of the inlet nozzle 17 and the hydraulic housing 2.

In a further embodiment, which is not shown, the inlet nozzle 17 and the stator 15 can be designed as a one-piece or one-piece component.

Instead of an inlet nozzle 17 connected indirectly to the hydraulic housing 2 via stator 15 and housing cover 3, an inlet nozzle 17 connected directly to the hydraulic housing 2 can also be provided. 2 shows the arrangement of the free end 19 of a first embodiment of the inlet nozzle 17 according to the invention in the recess 20, the left area of FIG. 2 showing the complete inlet nozzle 17 and the right area essentially showing the free end 19 of the same. The section 18 is divided into a first section 22 and a second section 23 near the free end 19. In the area of the free end 19, the second section 23 comprises a sleeve- or ring-like expansion element 24. The expansion element 24 and the first section 23 are welded together. The inner surface of the expansion element 24 and the inner surface of the first section 22 of the section 18 are essentially aligned. The material of the expansion element 24 has a higher thermal expansion coefficient than the material of the hydraulic housing 2 and/or the section 18. The expansion element 24 has a contact surface 25 facing the first section 22, which includes an annular axial elevation 26 and an axial recess 27. The first section 22 has a contact surface 28 directed towards the expansion element 24, which is at least partially designed to be complementary to the contact surface 25 of the expansion element 24. In particular, the contact surface 28 has a groove 29 into which the elevation 26 engages.

Thus, during operation, an exact alignment of the second section 23 or the expansion element 24 to the first section 22 is possible without a significant step. The inner lateral surface of the expansion element 24 and the inner lateral surface of the first section 22 are essentially in alignment in a flow-efficient manner.

The welding can be a partial welding, as shown in Figure 2, or a continuous welding over the complete radial extent of the section 23.

The annular gap 21, which has a radial gap width w, is designed such that in the cold state of the centrifugal pump 1, a backflow of the pumped medium via the annular gap 21 into the inlet opening 6, thus from the high-pressure area via the annular gap 21 into the low-pressure area, is possible. During operation with a usually hot conveying medium, the free end 19, in particular the expansion element 24, expands. Since the material of the expansion element 24 has a higher thermal expansion coefficient than the material of the hydraulic housing 2, the expansion element 24 comes into contact with the hydraulic housing 2 in the recess 20 of the inlet opening 6, in particular due to its expansion in the radial direction, or at least reduces the annular gap 21 in radial direction.

3 shows a further embodiment of the inlet nozzle 17 according to the invention. The left area of FIG of the free end 19, the sleeve or ring-like expansion element 24 and a holding device 30 that at least partially surrounds the expansion element 24. The holding device 30 is formed in one piece with the first section 22 and thus forms an area with an enlarged inner diameter. The expansion element 24 is arranged in the holding device 30. Expansion element 24 and holding device 30 are connected to one another by means of a shrink fit. In this embodiment too, the inner lateral surface of the expansion element 24 and the inner lateral surface of the first subsection 22 of the section 18 are essentially aligned. The material of the expansion element 24 has a higher coefficient of thermal expansion than the material of the hydraulic housing 2 and the holding device 30. The holding device 30 has an area 31 with an enlarged inner diameter, so that the holding device 30 has a certain flexibility in the radial direction.

During operation with a hot pumped medium, the expansion element 24 expands. Through its radial expansion component, the expansion element 24 brings the flexibly arranged holding device 30 in the recess 20 of the inlet opening 6 into contact with the hydraulic housing 2 or at least reduces the annular gap 21, in particular the radial gap width w, in the radial direction.

Due to the described embodiments of the inlet nozzle 17, the volumetric ones are reduced in hot operation by narrowing or closing the annular gap 21 Reduced losses and increased pump efficiency. The expansion element 24 preferably comprises austenitic steel.

Claims

Pump arrangement (1), in particular a centrifugal pump arrangement, with a hydraulic housing (2), a suction port (5) formed on the hydraulic housing (2) with an inlet opening (6), a pressure port (7) formed on the hydraulic housing (2) with an outlet opening ( 8), a flow chamber (11) at least partially delimited by the hydraulic housing (2), a housing cover (3) closing the hydraulic housing (2), a housing cover (3) arranged in the flow chamber (11) via a shaft (9) about an axis of rotation (A) drivable impeller (14), and an inlet nozzle (17) with a first end (16) connected directly or indirectly to the hydraulic housing (2) and a substantially cylindrical section (18) which is coaxial with the axis of rotation (A) in the direction of the inlet opening (6), wherein a second, free end (19) opposite the first end (16) is arranged at the transition from the inlet opening (6) to the flow chamber (11) in a recess (20) of the inlet opening (6) and in the area of Recess (20) between the section (18) of the inlet nozzle

(17) and the hydraulic housing (2) a radial annular gap (21) is created, characterized in that the section (18) is divided into a first section (22) and a second section (23) close to the free end (19) and in the area of the free end (19) the second section (23) comprises a sleeve- or ring-like expansion element (24), the material of the expansion element (24) having a higher thermal expansion coefficient than the material of the hydraulic housing (2). Pump arrangement (1) according to claim 1, characterized in that the material of the expansion element (24) comprises austenitic steel. Pump arrangement (1) according to one of claims 1 or 2, characterized in that the expansion element (24) and first section (23) are welded together. Pump arrangement (1) according to one of claims 1 to 3, characterized in that the expansion element (24) has a contact surface (25) facing the first section (22), which has an annular axial elevation (26) and an axial recess (27). comprises pump arrangement (1) according to one of claims 1 to 4, characterized in that the first section (22) has a contact surface (28) directed towards the expansion element (24), which is at least partially complementary to the contact surface (25) of the expansion element (24). is trained. Pump arrangement (1) according to one of claims 1 or 2, characterized in that the second section (23) close to the free end (19) in the area of the free end (19) has the sleeve- or ring-like expansion element (24) and the expansion element (24) at least partially surrounding holding device (30). Pump arrangement (1) according to claim 6, characterized in that the holding device (30) is formed in one piece with the first section (22) and the expansion element (24) is arranged in the holding device (30).

8. Pump arrangement (1) according to one of claims 6 or 7, characterized in that the expansion element (24) and holding device (30) are connected to one another by means of a shrink press fit. 9. Pump arrangement (1) according to one of claims 6 to 8, characterized in that the holding device (30) has a region (31) with a reduced inner diameter, such that the holding device (30) has flexibility in the radial direction.