Pump Assembly

Abstract

The present invention relates to a pump assembly comprising an outer casing (1), an insert (2) at least partially disposed in the outer casing (1), the insert (2) comprising a shaft (3) rotatable about a rotation axis (A) by a drive device, at least two pressure stages each having a pressure stage housing (5, 5'), an impeller (4) disposed on the shaft (3) and surrounded by a pressure stage housing (5, 5') in each pressure stage, and a seal (12) separating a first pressure chamber (11) from a second pressure chamber (13). According to the present invention, the pressure stage housing (5') comprises a first part (16) and a second part (17), the first part (16) having a first region (18) with an enlarged inner diameter and a second region (19) with a reduced inner diameter, the second part (17) having at least one first portion (20) with a reduced outer diameter and a second portion (21) with an enlarged outer diameter, the first region (18) of the first part (16) surrounding the first part (20) and at least partially surrounding the second portion of the second part (17), an annular chamber (25) being formed between the first part (16) and the second part (17), the annular chamber (25) being connected to the second pressure chamber (13).

Description

Technical Field

[0001] The present invention relates to a pump assembly having a barrel casing and a plug-in unit disposed at least partially within the barrel casing, the plug-in unit being arranged to be rotatable about a rotational axis by a drive device, and having a shaft, at least two pressure stages each having a pressure stage casing, an impeller disposed on the shaft and surrounded by the pressure stage casing in each pressure stage, and a seal separating a first pressure chamber from a second pressure chamber.

[0002] This type of centrifugal pump assembly, also known as a double-casing or barrel-casing pump, is disclosed, for example, in German Patent Application Publication No. 19927135.

[0003] In the case of this type of centrifugal pump, the centrifugal pump is surrounded by a barrel-shaped casing. The suction and pressure nozzles, and optionally the barrel casing provided with an intermediate discharge point, are closed by a cover in a plane perpendicular to the shaft. These are usually multi-stage pumps for use as high-pressure and ultra-high-pressure pumps, particularly also as boiler feed pumps. A plurality of pressure stage casings are arranged in series axially one behind the other within the barrel casing. Each pressure stage comprises a pump impeller and optionally a stationary stator.

[0004] The individual pressure stage casings of each pressure stage are usually formed together with the pump shaft as an integral pump plug-in unit. The flow transition from the last stator or the last pressure stage casing to the pressure nozzle is usually effected via a flow space formed in the barrel casing or via a separate plug-in unit for the end coil in the transition region.

[0005] Feed pumps often have multiple pressure regions within an externally recognizable barrel casing that constitutes the pressure casing. To the extent that the pressure regions are in contact with each other, they must be sealed to one another in all possible operating modes, i.e., under all resulting loads. This is usually achieved using special fixed seals. However, during operation, i.e., under load, the mounting space provided for these seals undergoes deformation or displacement compared to the unloaded state, which can introduce serious stress on the seals and make them less reliable in their sealing function.

[0006] Therefore, the present invention is based on the objective of providing a general pump assembly that eliminates the cause of this sealing problem, which is excessive deformation difference of the components surrounding the seal.

[0007] This objective is achieved by the pump assembly according to the features of claim 1. Advantageous embodiments of centrifugal pumps are the subject of the dependent claims.

[0008] According to the present invention, the pressure stage casing comprises a first part and a second part, wherein the first part has a first region having an enlarged inner diameter and a second region having a reduced inner diameter, and the second part has at least one first portion having a reduced outer diameter and a second portion having an enlarged outer diameter, and the first region of the first part surrounds the first portion and at least partially surrounds the second portion of the second part, and an annular chamber is formed between the first part and the second part.

[0009] The outer diameter of the second portion of the annular disc-shaped part and the inner diameter of the first region of the sleeve-shaped part are advantageously formed such that, in their overlapping region, the first region is spaced apart from or in contact with the second portion with very little play, thereby preventing or limiting deformation of the first region of the sleeve-shaped part inward or in the direction of the rotational axis.

[0010] The second portion of the annular disc-shaped part advantageously has means for connecting the annular chamber to the second pressure chamber.

[0011] According to the present invention, the second part of the second part has a barrel surface, and the barrel surface is provided with at least one groove connected to or directly attached to an annular chamber.

[0012] In a further advantageous embodiment, the annular disc-shaped part has a third portion that abuts against a second portion of the second part and forms a channel together with the barrel casing, having at least one axial groove extending parallel to the axis of rotation on the outer barrel surface of the third portion or at least one axial bore extending parallel to the axis of rotation near the outer barrel surface, the axial groove and the axial bore opening into the second pressure chamber.

[0013] A radial and circumferential gap is advantageously provided at the transition from the second to the third portion, the gap being connected on one side to at least one groove and on the other side to at least one axial groove or at least one axial bore extending to the outer barrel surface of the third portion.

[0014] In an advantageous alternative embodiment, the second part has at least one axial bore that extends substantially parallel to the axis of rotation and directly connects the annular chamber to the second pressure chamber.

[0015] Exemplary embodiments of the invention are shown in the drawings and will be described in more detail below. [Brief explanation of the drawing]

[0016] [Figure 1] This shows a cross-sectional view of a pump assembly equipped with a first embodiment of the pressure stage casing according to the present invention. [Figure 2] A magnified, detailed view of Figure 1 is shown. [Figure 3]Figures 1 and 2 show partial cross-sectional views of the stepped casing according to the present invention in embodiments. [Figure 4] This shows a partial cross-sectional view of a second embodiment of the stepped casing according to the present invention in an installed state. [Figure 5] Figure 4 shows a partial cross-sectional view of the stepped casing. [Figure 6] This shows a partial cross-sectional view of a third embodiment of the stepped casing according to the present invention in an installed state.

[0017] Figure 1 shows a pump assembly with a barrel casing 1, designed as a centrifugal pump. A plug-in unit 2 is located at least partially within the barrel casing 1. The plug-in unit 2 includes a shaft 3, which is arranged to be rotatable around a rotation axis A by a drive unit (not shown), such as an electric motor. In the exemplary embodiment shown, a plurality of impellers 4 are arranged in succession on the shaft 3. In the exemplary embodiment, the impellers 4 are radial wheels.

[0018] The plug-in unit 2 further comprises a plurality of so-called pressure stage casings 5, the pressure stage casings according to the present invention being indicated by reference numeral 5'. Each impeller 4 is surrounded by a pressure stage casing 5 or 5'. Adjacent pressure stage casings 5, 5' are in contact with each other. In an exemplary embodiment, a dividing line between the pressure stage casings 5, 5' provides a metal seal.

[0019] Stators 6, positioned behind each impeller 4 in the flow direction of the conveyed medium, are provided in each pressure stage casing 5, 5'. The stators 6 are non-rotatably connected to the pressure stage casings 5, 5' by interference fit or other suitable means. A suction nozzle 7, through which the working medium enters the centrifugal pump, is molded into the barrel casing 1. The working medium exits the pump assembly through a pressure nozzle 8. In the illustrated exemplary embodiment, the barrel casing 1 has an intermediate discharge section 9. A predetermined proportion of the conveyed medium can be conveyed into a first pressure chamber 11 located between the pressure stage casings 5, 5' and the barrel casing 1 through at least one radial opening 10 in one of the central pressure stage casings 5, and discharged through the intermediate discharge section 9. A seal 12 separates the pressure chamber 11 from a second pressure chamber 13 located near the pressure nozzle 8, particularly below the inflow area to the pressure nozzle 8, or inside the pressure nozzle 8. In this case, the pressure in the second pressure chamber 13 is at least the pressure of the stage, and at most n-1 times the pressure of the stage, higher than the pressure in the pressure chamber 11, where n is the number of stages.

[0020] Figure 1 shows a multistage pump assembly comprising six pressure stages and five pressure stage casings 5, 5'. It is obvious that the number of pressure stages must be at least two, but can otherwise be arbitrarily varied. Furthermore, it is conceivable that all pressure stages are formed by the pressure stage casings 5' according to the present invention.

[0021] As can be seen in Figure 2, which shows an enlarged detail of Figure 1, the seal 12 separates the pressure chamber 11, which tapers toward the seal 12, from a channel 15 communicating with the second pressure chamber 13 in the region of the pressure nozzle 8, to a relatively narrow first annular gap 14. Figure 2 also shows how the seal 12 interacts with the barrel casing 1 and the pressure stage casing 5' according to the present invention, the arrangement of the stators 6, and the arrangement of the impellers 4 positioned on an axis 3 that rotates about a rotation axis A within the pressure stage casing 5'.

[0022] Figure 3 shows a separate view of the cup-shaped or pot-shaped pressure stage casing 5' according to Figure 2. The pressure stage casing 5' includes a sleeve-shaped first part 16 and an annular disk-shaped second part 17. The sleeve-shaped first part 16 has a first region 18 with an enlarged inner diameter and a second region 19 with a reduced inner diameter.

[0023] At the transition from the first region 18 to the second region 19 of the sleeve-shaped first part 16, the sleeve-shaped part 16 is connected to the annular disk-shaped second part 17. The two parts 16 and 17 may be welded to each other or manufactured integrally, for example, by 3D printing. In a further alternative, the parts 16 and 17 can be screwed together.

[0024] The annular disk-shaped part 17 has a first portion 20 and a second portion 21 with a barrel surface 22. In the exemplary embodiment shown, the barrel surface 22 is substantially cylindrical in design but also has a conical portion. At least one groove 23 is provided in the barrel surface 22, and this groove 23 causes the portion 21 to show a recess and a protrusion 24 with the barrel surface 22. In the exemplary embodiment shown, at least one groove 23 extends substantially parallel to the axis of rotation A.

[0025] The first region 18 of the sleeve-shaped part 16 surrounds both the first portion 20 of the annular disk-shaped second part 17 and also partly the second portion 21. The outer diameter of the first portion 20 is smaller than the outer diameter of the second portion 21. The outer diameter of the second portion 21 of the annular disk-shaped part 17 and the inner diameter of the first region 18 of the sleeve-shaped part 16 are formed such that in their overlapping region, the first region 18 is spaced from the second portion 21 or abuts the second portion 21 with a very small clearance.

[0026] The first part 20 of the annular disk-shaped second part 17 has a smaller outer diameter compared to the second part 21, thereby forming an annular chamber 25 between the sleeve-shaped first part 16 and the annular disk-shaped part 17. The annular chamber 25 is connected to at least one groove 23 or is fluidly directly connected to the groove 23 in form. The first region 18 of the sleeve-shaped part 16 is elastically formed within a predetermined limit by the annular chamber 25.

[0027] The barrel surface 22 of the protrusion 24 prevents or limits the deformation of the elastic region 18 of the sleeve-shaped part 16 in the inward or in the direction of the axis of rotation A.

[0028] The part 17 further has a third part 26 adjacent to the second part 21 on the side opposite to the annular chamber 25.

[0029] The outer diameter of the second part 21 is smaller than the outer diameter of the third part 26. In the embodiment shown as an example, the third part 26 may have a step provided for fixing the pressure stage casing 5' to the barrel casing if necessary.

[0030] The channel 15 shown in FIG. 2 is formed by at least one axial groove (not shown) extending axially on the outer barrel surface 27 of the third part 26, and this axial groove interacts with the barrel casing 1, and a radial connecting groove (not shown) is provided in the region of the step, and this connecting groove connects two axial groove portions on the outer barrel surface 27 to each other. Alternatively, the axial groove and the connecting groove may be formed in the barrel casing 1.

[0031] Since the first region 18 of the sleeve-shaped part 16 does not completely enclose the second portion 21, a radial and circumferential gap 28 connected to at least one groove 23 is formed at the transition from the second portion 21 to the third portion 26. The gap 28 is further in communication with an axial groove extending axially on the outer barrel surface 27 of the third portion 26, and thus with the channel 15 and pressure chamber 13 shown in Figure 2.

[0032] A chamfered portion is provided at the transition from the first region 18 to the second region 19 of the sleeve-shaped first part 16, meaning that the outer diameter of the sleeve-shaped part 18 is larger than the outer diameter of region 19, and the seal 12 can be assembled without any problems.

[0033] Figure 4 shows a further embodiment of the pressure stage casing 5' according to the present invention in an installed state.

[0034] Figure 5 shows in detail the pressure stage casing 5' shown in Figure 4. The first sleeve-like part 16 substantially corresponds to the embodiment of the pressure stage casing 5' shown in Figures 1 to 3 and requires no further explanation. The second part 21 of the second part 17, which has at least one groove 23, at least one projection 24, and a barrel surface 22, and the annular chamber 25 substantially corresponds to the embodiment described with reference to Figures 1 to 4.

[0035] In the embodiment of the pressure stage casing 5' shown in Figures 4 and 5, at least one axial bore 29, formed substantially parallel to the rotation axis A, is provided in the third portion 26, communicates with the gap 28, and opens into the second pressure chamber 13 in the region of the pressure nozzle 8.

[0036] In the embodiment shown, no stepped portion is provided in portion 26, but a stepped portion may be provided as shown in Figures 2 and 3.

[0037] As shown in Figure 6, in a further embodiment of the pressure stage casing 5', at least one axial bore 29 can be connected to or directly attached to the annular chamber 25, extending through the second portion 21 and the third portion 26 and opening into the second pressure chamber 13. Thus, the axial bore 29 directly connects the annular chamber 25 to the second pressure chamber 13 in the region of the pressure nozzle 8. The grooves on the barrel surface 22 can be omitted in this case.

[0038] In the embodiment shown as an example, the third portion 26 has a stepped section, but this stepped section is not necessary in the case of a fixed type of pressure stepped casing 5' as shown in Figures 4 and 5.

[0039] When the pump assembly is activated, the medium is drawn into the pump through the suction nozzle 7 and flows to the first pressure stage casing 5 connected downstream of the suction nozzle. The medium is then guided to the next pressure stage casing 5 by the impeller 4 via the stator 6, which is connected later or located downstream. A portion of the medium is transported into the pressure chamber 11 through at least one opening 10 in the stage casing 5 closest to the intermediate discharge section 9, from which the medium can be transported from the pump through the intermediate discharge section 9. The majority of the medium is supplied to the next pressure stage casing 5 in the corresponding form.

[0040] In terms of flow, the final stator 6 transports the medium into the pressure chamber 13. From there, portions of the medium according to Figures 1-3 pass through at least one channel 15 and a radially and circumferential gap 28 into at least one groove 23 in the second portion 21, and then into the annular chamber 25, or, according to Figures 4 and 5, through at least one axial bore 29 and a radially and circumferential gap 28 into at least one groove 23, and then into the annular chamber 25, or, according to Figure 6, directly from the pressure chamber 13 into the annular chamber 25 via at least one axial bore 29. The pressure chamber 13 forms a system filled with medium in a space that communicates with at least one channel 15 or at least one axial bore 29, a radially and circumferential gap 28, at least one groove 26 and the adjacent annular chamber 25.

[0041] In the annular chamber 25, overpressure is generated relative to the chamber 11, and this overpressure expands region 18, thereby causing it to contact the barrel radially. As a result, the radial range of the sealing space remains substantially constant under all operating conditions.

Claims

1. A pump assembly, Barrel casing (1), A plug-in unit (2) at least partially disposed in the barrel casing (1), wherein the plug-in unit (2) comprises an axis (3) arranged to be rotatable about a rotation axis (A) by a drive device, and at least two pressure stages, each having a pressure stage casing (5, 5'), An impeller (4) is positioned on the shaft (3) and surrounded by the pressure stage casings (5, 5') in each pressure stage, A seal (12) separates the first pressure chamber (11) from the second pressure chamber (13), It has, The pressure stage casing (5') comprises a first part (16) and a second part (17), The first part (16) has a first region (18) having an enlarged inner diameter and a second region (19) having an inner diameter smaller than the inner diameter of the first region (18), The second part (17) has at least one first portion (20) having a reduced outer diameter and a second portion (21) having an outer diameter that is larger than the outer diameter of the first portion (20), The first region (18) of the first part (16) surrounds the first portion (20) and at least partially surrounds the second portion of the second part (17), An annular chamber (25) is formed between the first part (16) and the second part (17), and the annular chamber (25) is connected to the second pressure chamber (13). A pump assembly characterized in that the outer diameter of the second portion (21) of the second part (17) and the inner diameter of the first region (18) of the first part (16) are formed such that, in their overlapping region, the first region (18) is spaced apart from or in contact with the second portion (21) with a very small amount of play.

2. The pump assembly according to claim 1, wherein the second part (17) has means (15, 23, 29) for connecting the annular chamber (25) to the second pressure chamber (13).

3. The pump assembly according to claim 2, characterized in that the second portion (21) of the second part (17) has a barrel surface (22) and the barrel surface (22) is provided with at least one groove (23) connected to the annular chamber (25).

4. The pump assembly according to claim 2 or 3, wherein the second part (17) has a third part (26) that abuts against the second part (21) of the second part (17), and at least one axial groove or at least one axial bore (29) is formed on the outer barrel surface (27) of the third part (26) parallel to the axis of rotation (A), and the axial groove and the axial bore (29) open into the second pressure chamber (13).

5. The pump assembly according to claim 4, characterized in that a radial and circumferential gap (23) is provided at the transition from the second portion (21) to the third portion (26), and the gap (28) is connected on one side to the at least one groove (23) and on the other side to the at least one axial groove or the at least one axial bore (29) extending to the outer barrel surface (27) of the third portion (26).

6. A pump assembly, Barrel casing (1), A plug-in unit (2) at least partially disposed in the barrel casing (1), wherein the plug-in unit (2) comprises an axis (3) arranged to be rotatable about a rotation axis (A) by a drive device, and at least two pressure stages, each having a pressure stage casing (5, 5'), An impeller (4) is positioned on the shaft (3) and surrounded by the pressure stage casings (5, 5') in each pressure stage, A seal (12) separates the first pressure chamber (11) from the second pressure chamber (13), It has, The pressure stage casing (5') comprises a first part (16) and a second part (17), The first part (16) has a first region (18) having an enlarged inner diameter and a second region (19) having an inner diameter smaller than the inner diameter of the first region (18), The second part (17) has at least one first portion (20) having a reduced outer diameter and a second portion (21) having an outer diameter that is larger than the outer diameter of the first portion (20), The first region (18) of the first part (16) surrounds the first portion (20) and at least partially surrounds the second portion (21), A pump assembly characterized in that an annular chamber (25) is formed between the first part (16) and the second part (17), the annular chamber (25) is connected to the second pressure chamber (13), and the second part (17) has an axial bore (29) that directly connects the annular chamber (25) to the second pressure chamber (13).

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