EP4305318A1

EP4305318A1 - Hybrid manufacture of an impeller

Info

Publication number: EP4305318A1
Application number: EP22710385.0A
Authority: EP
Inventors: Tammuz NOBEL
Original assignee: KSB SE and Co KGaA
Current assignee: KSB SE and Co KGaA
Priority date: 2021-03-09
Filing date: 2022-03-04
Publication date: 2024-01-17
Also published as: WO2022189289A1; JP2024510980A; US20240151243A1; CN116964334A; DE102021105624A1

Abstract

The invention relates to a centrifugal pump (1) comprising at least one impeller (5, 9). A guide element (23) is located downstream of the impeller. The guide element (23) is designed as a hybrid component that consists of at least one conventionally manufactured component and at least one generatively manufactured component.

Description

description

Production of an idler wheel in a hybrid way

The invention relates to a centrifugal pump with at least one impeller, which is followed by a control device.

Pumps are referred to as multi-stage when several impellers are arranged one behind the other and the flow rate flows through them in series. Boiler feed pump is another name for the feed pump and is a multi-stage centrifugal pump. Their task is to feed the amount of feedwater corresponding to the amount of steam emitted back to a steam generator such as a boiler or nuclear reactor.

The pot case pump, in power plant technology the feed pumps are also referred to as jacket case pump or pot case pump, is a centrifugal pump surrounded by a pot-like housing. The pot, which is provided with a suction socket and a pressure socket, is screwed to the front sides with a pressure cover and an inlet ring. The drive shaft is routed through the cover on the pressure side and through the inlet ring on the suction side, each sealed with a shaft seal. When the pump is dismantled, the pot housing can remain connected to the pipes and the pump foundation. In the case of the high-pressure pump, the barrel housing is often also welded into the pipeline. Pot case pumps are multi-stage pumps in a horizontal design. They are used as high and high pressure pumps, especially as boiler feed pumps. In multi-stage centrifugal pumps, a control device is usually arranged between two impellers. Guide devices usually have guide vanes and form guide channels for the pumped medium between two guide vanes. Such Leiteinrich lines can be designed as guide wheels. Conveyed medium emerging from the impeller enters the guide device. Kinetic energy is converted into pressure energy in the guide device. Furthermore, a deflection of the medium takes place. If necessary, the swirl is reduced for an inflow into a following impeller.

DE 39 12279 C2 describes a centrifugal pump of single or multi-stage design with at least one impeller. A guide wheel is arranged downstream of the impeller in the direction of flow. The guide wheel has several guide vanes.

The impellers and in particular the guide devices are characterized by a massive and not very filigree design, which is usually produced by forming and primary forming processes. An increase in pump efficiency is usually limited by the massive and poorly flow-optimized design of the guide devices. Especially in continuous use as a boiler feed pump, small increases in efficiency produce a large economic impact.

The object of the invention is to specify a centrifugal pump, also a multi-stage centrifugal pump, with an optimized flow control. The centrifugal pump should have the highest possible efficiency. Flow separation should be largely prevented and deceleration with as little loss as possible should be ensured. The centrifugal pump should be able to be designed individually to customer requirements. This centrifugal pump should consist of as few individual parts as possible and should be as easy to assemble as possible. The exchange of spare parts should be favored by the construction of the centrifugal pump. The centrifugal pump should be easy and inexpensive to implement.

According to the invention, this object is achieved by a centrifugal pump with at least one impeller. Preferred variants can be found in the dependent claims, the description and the drawings. According to the invention, a guide device of a centrifugal pump is constructed as a hybrid component from at least one conventionally manufactured component and at least one additively manufactured component.

An additively manufactured component has been created using an additive manufacturing process. The term generative manufacturing processes includes all manufacturing processes in which material is applied layer by layer and thus three-dimensional components are produced. The layered structure is computer-controlled and consists of one or more liquid or solid materials according to specified dimensions and shapes. Physical or chemical hardening or melting processes take place during construction. Typical materials for 3D printing are plastics, synthetic resins, ceramics, metals, carbon and graphite materials

Additive manufacturing processes are processes in which material is applied layer by layer to create a three-dimensional component. According to the invention, at least one guide element of the guide device is designed as an additively manufactured component. In particular, selective laser melting and cladding, also known as build-up welding, are used to form the guide elements. In an alternative variant of the invention, cold gas spraying and extrusion in combination with the application of meltable plastic can also be used.

Advantageously, generatively manufactured guide elements are particularly filigree and thin-walled. Fine webs, flow-optimized using CFD, direct the flow from the preceding impeller to the following impeller with almost no loss. The complex structure of the guide element prevents the formation of vortices and flow separation and is characterized by a low component mass.

In the case of selective laser melting, the guide element is produced using a method in which a layer of a building material is first applied to a substrate. The construction material for the production of the Guide element of the guide to metallic powder particles. In a variant of the invention, iron-containing and/or cobalt-containing powder particles are used for this purpose. These can contain additives such as chromium, molybdenum or nickel. The metallic structure material is applied in powder form in a thin layer to a plate. The powdered material is then completely melted locally by means of radiation at the desired locations and a solid layer of material is formed after solidification. The base is then lowered by the amount of one layer thickness and powder is applied again. This cycle is repeated until all layers have been produced and the finished guide element has been created. According to the invention, a structure is created that is particularly filigree and flow-optimized and cannot be technically created by conventional methods.

A laser beam, for example, can be used as radiation, which generates the guide element from the individual powder layers. The data for guiding the laser beam are generated using software on the basis of a 3D CAD body. As an alternative to selective laser melting, an electron beam (EBN) can also be used.

In build-up welding or cladding, the guide element is manufactured using a process that coats a base structure by welding. The surfacing builds up a volume with a filler material in the form of a wire or powder, which creates a particularly filigree and flow-optimized shape of the guide element.

For the application of multi-section high-pressure centrifugal pumps and boiler feed pumps, it has not been possible to use generatively manufactured control devices, as their dimensions were technically impossible or difficult to realize. Additively manufactured components of the guide systems are characterized by hydraulically optimized geometries that cannot be achieved with machining or casting production processes. The formation of a hybrid control system using a large number of generatively manufactured control elements based on conventionally manufactured components on the one hand enables a hydraulically optimized geometry and on the other hand component sizes that exceed the known, generatively possible production dimensions.

According to the invention, the guiding device has more than two, preferably more than three, in particular more than four, and/or fewer than twenty, preferably less than eighteen, in particular fewer than sixteen, guiding elements. Advantageously, a hybrid guide device can thus be generated, which consists of a large number of additively manufactured and hydraulically optimized guide elements. The component size of a guide element can be generated by the usual additive processes with all their advantages and can also achieve very large dimensions thanks to the hybrid structure with conventional components.

Advantageously, the generatively manufactured component, in particular the guide element, has a shape that is curved radially outwards. The shape of the guide element with its filigree webs has been hydraulically optimized using CFD and deflects the flow with a reduction in swirl, without flow separation and vortex formation. The radially curved shape of the guide element directs the flow to the next pump stage in a particularly ideal way.

In a particularly favorable embodiment of the invention, the additively manufactured component, in particular the guide element, has formations for guiding the flow.

These are particularly finely executed mouldings, webs and curves in the guide element, which optimize the hydraulic efficiency of the pump in a very advantageous way. They allow the flow to be redirected to the next pump stage and ideally reduce the swirl of the flow.

In this case, a guide element preferably has a first, front projection, which, in the form of a receiving blade, absorbs the impeller discharge that hits the guide elements through the gap in the conventionally manufactured double ring. The receiving molding guides the flow to a second molding with particularly low losses which forms a flow channel with the round ring of the double ring and an adjacent guide element. The flow is redirected using the flow channel so that it flows in the direction of the downstream impeller. In this case, the flow preferably passes through a rear molding of the guide element, which has an outflowing blade contour. This outflowing blade contour enables a particularly twist- and loss-free outflow to the next pump stage of the multi-stage centrifugal pump.

Ideally, the projections are particularly filigree and have particularly finely defined radii of curvature. The guide element preferably has reinforcing struts in places that do not affect the flow. The additively manufactured guide element is therefore particularly thin and at the same time extremely robust. A guide element with such finely defined blade contours cannot be manufactured using known conventional manufacturing processes and increases the efficiency of the pump in a very advantageous way.

According to the invention, the generatively manufactured component, in particular the guide element, encloses a guide ring with almost no gaps. As a result, faulty flows and efficiency losses are avoided. The generative manufacturing of the guiding elements allows an extremely precise and accurate manufacturing and thus a gap-free fit to the conventionally manufactured components of the hybrid guiding device.

Ideally, an additively manufactured component, in particular the guide element, has sealing elements for a gap-free connection to a guide ring. The generative manufacturing process allows a finely designed geometry of the guide element, so that when the hybrid elements of the guide device are brought together, a gap-free connection can be realized, whereby the efficiency of the centrifugal pump can approach the hydraulic optimum.

In an alternative variant of the invention, the walls of the guide elements are made very thin and the guide elements have an inner wall to increase their strength lattice structure. In this advantageous way, guide elements with a particularly excellent ratio of mass to component volume can be achieved. Especially in comparison to conventionally manufactured guide devices, the hybrid design of the guide devices has a low mass.

In a particularly advantageous embodiment of the invention, the hybrid design of the guide device does not require any additional joining technology. According to the invention, the generatively manufactured component, in particular the guide element, has elements for engaging in counter-elements. For example, short, cylindrical pins can be formed on the control element, which can be inserted into corresponding negatives on the conventional component and thus form a stable bond. This considerably simplifies the assembly of the centrifugal pump, since the components of the hybrid guide device can simply be plugged in.

Ideally, the elements for engaging are formed as so-called pins or pens, which can engage in a connecting manner in the corresponding counter-elements, which are formed as precisely fitting negatives of the pins or pens. The resulting plug connection is characterized by simple assembly and disassembly.

The term "conventional component" designates a component that is produced by means of archetypes, forming or a subtractive manufacturing process. Primary shaping is a main group of manufacturing processes in which a solid body with a geometrically defined shape is produced from an amorphous substance. Primitive Forming is used to create the initial form of a solid body and to create the cohesion of matter. During forming, raw parts made of plastically deformable materials are specifically brought into a different shape without removing any material from the raw parts. In the subtractive manufacturing process, something is separated from the workpiece. In addition to the component produced, this mainly produces chips.

According to the invention, at least one conventionally manufactured component is designed as a one-piece double ring. Simple rings can be produced particularly economically and precisely by casting. The hybrid design of the control device combines Components that have each been hydraulically optimized using the most advantageous manufacturing process to create a device that achieves the best possible efficiency of a multi-stage centrifugal pump.

Advantageously, a conventionally manufactured component includes a rounded guide ring and an edged ring. The rounded guide ring is characterized by a flow-optimized curve on which the guide elements can be arranged without a gap. The edged ring is particularly advantageous for the connection to the impeller, which allows the impeller discharge to be discharged directly to the radially surrounding guide device.

According to the invention, the conventionally manufactured component is designed as a one-piece double ring, the rings of which are connected with at least two connecting webs. The connecting webs realize a fixed attachment and arrangement of the rounded guide ring to the edged ring. At the same time, the gap between the rings has a sufficiently large passage for flow deflection through the guide elements.

Ideally, at least one conventionally manufactured component, in particular the guide ring, has counter elements for the engagement of elements. For example, the counter-elements can be designed as cylindrical depressions into which the pin-like elements of the guide elements engage and thus realize the plug-in connection between the guide elements and the guide ring. This makes the installation of the hybrid guidance system particularly easy and time-efficient.

In an alternative variant, the generatively manufactured components and the conventionally manufactured components are joined to form a guiding device with a non-detachable connection, preferably a welded connection. Such a connection is characterized by its robust and durable design. When joining, two or more solid bodies, the joining parts, are permanently connected with a geometrically determined shape. Welding creates an inseparable connection between guide elements and the guide ring using heat and/or pressure, with or without welding filler materials. The additional materials are usually added in the form of rods or wires, melted and solidified in the joint between the joining partners in order to create the connection. Welding is one of the material-to-material connection methods, whereby high-strength connections are created.

The manufacture of large, hybrid control systems using an integrative, additive manufacturing process is of particular advantage. In this case, the one-piece double ring is first formed by archetypes and/or machining. The guide elements are created using a generative process. The hybrid guide device is completed by plugging the guide ring together with the guide elements.

The structural material for producing the contact surface for the flowing fluid of the guide element is preferably metallic powder particles. In a variant of the invention, iron-containing and/or cobalt-containing powder particles are used for this purpose. These can contain additives such as chromium, molybdenum or nickel.

According to the invention, at least one guide element of the guide device is formed in an additive manufacturing process. The 3D shape of a guide element is stored in software as a data record. At the points where the guide element is to be formed, a robot arm, which has tools from different additive processes, acts and forms the contact surface to the flowing medium and the supporting lattice structure of the contact surfaces layer by layer. Advantageously, the appropriate build-up process for each build-up material can be carried out for each layer in succession or simultaneously, so that a complex guide element is also created from different materials, the areas of which are optimally adapted to the requirements of later use. In one variant of the invention, a lattice structure is produced using the melt layer tool of the additive manufacturing process, in which a grid of points is applied to a surface from meltable plastic. A stable structure, in particular in the form of a lattice and/or in the form of honeycombs, is produced by extrusion using a nozzle and subsequent hardening by cooling at the desired position. Because the supporting area of a guide element is created in a cavity-forming manner with a particularly load-bearing structure, a guide element has enormous strength while at the same time having a very low mass. A guiding element is usually built up by repeatedly traveling along a working plane line by line and then shifting the working plane upwards in stacks, so that the supporting area of a guiding element is created.

In a particularly advantageous variant of the invention, the contact surface for the flowing fluid of the guide element is produced from a structural material by means of successive melting and solidification of layers by means of radiation. The different properties of the areas of a guide element are generated by variations in the radiation. Through targeted control of the local heat input, a modification of the material properties is already carried out during the construction of the guide element. This makes it possible to create zones and structures of different material states of a chemically homogeneous material and thus different properties in one area of the guide element.

The metallic structure material is applied in powder form in a thin layer to a plate. The powdery material is completely locally melted at the desired points by means of radiation and forms a solid material layer after solidification. This base plate is then lowered by the amount of one layer thickness and powder is applied again. This cycle is repeated until all layers are made. The finished guide element is cleaned of excess powder. The hybrid design of the guidance system enables guidance systems that can be designed particularly individually. Adjustments to the guide device, in particular the vane-like guide elements, can be taken into account by the gene rative production, depending on the requirements of the centrifugal pump. The expensive one-off production is significantly cheaper due to the comparatively cheap, hybrid design from conventionally and additively manufactured components. In addition, the generatively manufactured components can have a shape that can achieve a higher pump efficiency and could not previously be achieved using conventional manufacturing methods.

Ideally, the guide device, which is produced hybrid from at least one generatively manufactured component and at least one conventionally manufactured component, is used as a guide device for a centrifugal pump, in particular for a multi-stage high-pressure pump. The guiding device is characterized by excellent flow-mechanical properties.

Further features and advantages of the invention result from the description of exemplary embodiments based on the drawings and from the drawings themselves.

It shows:

1 is a perspective view of a guide device,

2 shows a schematic representation of a guide element.

Fig. 1 shows a perspective view of the guide device 23 according to the invention. The guide device 23 comprises the one-piece double ring 22, which is composed of the rounded guide ring 19, the edged ring 20 and the connecting webs 18 together. The guide ring 19 has counter-elements 21 into which the elements 24, not shown in this figure, engage. Furthermore, a guiding element 17 is arranged on the guiding ring 19 of the guiding device 23 in FIG. 1 by way of example. The guide device 23 according to the invention comprises more than two, preferably more than three, in particular more than four and/or less than twenty, preferably less than eighteen, in particular less than sixteen, generatively manufactured guide elements 17.

The edged ring 20 surrounds an impeller, not shown, radially and catches the Fluident charge of the impeller. The fluid flow flows through the gap between the rounded guide ring 19 and the edged ring 20 from the guide elements 17 to. The Leitele elements 17 deflect the fluid flow through their radially outwardly curved shape and the formations for flow guidance 25 with a reduction in swirl. The guide elements 17 avoid the formation of vortices and flow separations due to their optimized flow form and thus contribute to increasing the efficiency of the centrifugal pump.

The guide device 23 is a hybrid component that is composed of the conventionally manufactured, one-piece double ring 22 and the additively manufactured guide element 17 . Thus, the hybrid structure of the guide device 23 combines the advantages of each respective manufacturing process to achieve the optimum efficiency of the inventions to the invention centrifugal pump.

The guide element 17 preferably has a first, front projection 27 which, in the form of a receiving blade, receives the impeller discharge which strikes the guide elements 17 through the gap in the conventionally manufactured double ring 22 . The receiving projection 27 leads the flow to a second projection 28 with particularly low losses, which forms flow channels with the round ring 19 of the double ring 22 and the adjacent guide elements 17 . The flow is redirected with the help of the flow channels so that it flows in the direction of the downstream impeller. The flow preferably passes through a rear projection 30 of guide element 17, which has an outflowing blade contour. This outflowing blade contour enables a particularly swirl- and loss-free outflow to the next pump stage of the multi-stage centrifugal pump.

In this exemplary embodiment, the formations for flow guidance 25 consist of the front projection 27, the second projection 28 and the rear projection 30. These shapes for guiding the flow are particularly filigree and designed with extremely fine radii of curvature. The guide element 17 preferably has reinforcement struts 29 at the connection points. Fig. 2 shows a schematic representation of the guide element 17, with its radially outwardly curved shape. The generatively manufactured guide element 17 has formations 25 for improved flow guidance and sealing elements 26 for a gap-free connection to the guide ring 19 (not shown). The elements 24 for engaging in the counter-elements 21 (not shown) enable the hybrid design of the guide device 23 to be plugged in.

Claims

patent claims

1. Centrifugal pump (1) with at least one impeller (5, 9), which is arranged downstream of a guide device (23), characterized in that the guide device (23) is constructed as a hybrid component from at least one conventionally manufactured component and at least one additively manufactured component.

2. Centrifugal pump according to claim 1, characterized in that at least one generatively manufactured component is designed as a guide element (17).

3. Centrifugal pump according to claim 1 or 2, characterized in that the Leitein direction (23) more than two, preferably more than three, in particular more than four, and / or less than twenty, preferably less than eighteen, in particular less than sixteen Having guide elements (17).

4. Centrifugal pump according to one of claims 1 to 3, characterized in that at least one generatively manufactured component has a radially outwardly curved shape.

5. Centrifugal pump according to one of claims 1 to 4, characterized in that at least one generatively manufactured component has formations (25) for Strö flow guidance.

6. Centrifugal pump according to claim 5, characterized in that the formations (25) for guiding the flow comprise at least one receiving formation (27), one channel-forming formation (28) and one rear formation (30) with outflowing blade contour.

7. Centrifugal pump according to one of claims 1 to 6, characterized in that at least one generatively manufactured component encloses a guide ring (19) almost without a gap.

8. Centrifugal pump according to one of claims 1 to 7, characterized in that at least one additively manufactured component has sealing elements (26) for gap-free connection to a guide ring (19).

9. Centrifugal pump according to one of claims 1 to 8, characterized in that at least one generatively manufactured component has elements (24) for engaging in counter-elements (21).

10. Centrifugal pump according to one of claims 1 to 9, characterized in that at least one conventionally manufactured component is designed as a one-piece double ring (22), the one-piece double ring (22) comprising a rounded guide ring (19) and an edged ring (20). .

11. Centrifugal pump according to one of claims 1 to 10, characterized in that at least one conventionally manufactured component has at least two connec tion webs (18) for connecting a guide ring (19) with an edged ring (20).

12. Centrifugal pump according to one of claims 1 to 11, characterized in that a conventionally manufactured component has counter-elements (21) for engaging elements (24).

13. Centrifugal pump according to one of claims 1 to 12, characterized in that an additively manufactured component and a conventionally manufactured compo nent with a non-detachable connection, preferably a welded connection, are connected.

14. Centrifugal pump according to one of claims 1 to 12, characterized in that an additively manufactured component and a conventionally manufactured compo nent with a detachable connection, preferably a plug connection, are connected.

15. Use of a hybrid component with at least one additively manufactured component and at least one conventionally manufactured component as a guide device (23) for a centrifugal pump (1) with at least one impeller (5, 9).