Centrifugal slurry pump impeller

Abstract

A centrifugal slurry pump impeller including: a front shroud, a back shroud, and a plurality of pumping vanes being disposed therebetween and in a spaced apart relation to one another around a central axis, with passageways between adjacent pumping vanes, and a projection extending from the back shroud along the central axis to a distal end forward of an outer face of the front shroud of the impeller, wherein the projection comprises one or more fins that project radially from a circumferential surface of the projection and that extend at least partially along a length of the projection.

Description

CENTRIFUGAL SLURRY PUMP IMPELLERTechnical Field

[0001] This disclosure relates generally to a pump impeller for use in centrifugal pumps. More particularly, though not exclusively, to pumps for handling abrasive materials such as for example slurries and the like.

[0002] Centrifugal slurry pumps generally comprise an outer casing that is formed from two side casing sections which are joined together and have an inlet and a discharge outlet to facilitate pumping of a mineral slurry from connected piping. A liner is arranged within the outer casing that includes a main liner and two side liners. One of the side liners, referred to as the back side part or frame plate liner insert, locates nearer to the rear end of the pump, or drive side, and the other side liner, referred to as the front side part or throatbush, locates nearer to the front end of the pump and inlet.

[0003] An impeller is positioned within the main liner and is operatively connected to the drive shaft that is adapted to rotate about a rotation axis X-X, or central axis. The rotation of the impeller causes the fluid (or solid-liquid mixture) being pumped to pass from a pipe which is connected to the inlet through a pumping chamber located within the main liner and the side liners, and then out of the pump via the discharge outlet.

[0004] The impeller comprises a front and back shroud, with pumping vanes extending from the back shroud in a direction generally in line with the axis of rotation X-X of the slurry pump impeller. Passageways are located between the pumping vanes through which the fluid passes from an impeller inlet. The inner face of the back shroud is generally in a plane which is at right angles to the axis of rotation X-X.

[0005] In some applications such as the alumina industry the solid, particulate matter or scale particles in a slurry is of such a size that it can cause clogging or damage to the impeller as the slurry passes therethrough.

[0006] AU 2002304980 provides an apparatus having an impeller with a rotatable part extending axially outward having grooves, or recesses, for breaking down, or grinding, the slurry being processed. The front side liner, or throatbush, has a straight inlet, and there is little clearance between the throatbush intake and the rotatable part. Whilst the grooves, or recesses aid in grinding the slurry, the small clearance may cause clogging.

[0007] AU 2021332086 improves on the above by increasing the inlet of the throatbush. The larger inlet slows the intake of slurry allowing further grinding and increases the clearance between the inlet and rotatable part thus reducing risk of clogging.

[0008] The present application seeks to provide an improved approach to removing or reducing large suspended solids from entering a centrifugal slurry pump to avoid such issues.Summary

[0009] According to one aspect there is provided a centrifugal slurry pump impeller including: a front shroud, a back shroud, and a plurality of pumping vanes being disposed therebetween and in a spaced apart relation to one another around a central axis, with passageways between adjacent pumping vanes, and a projection extending from the back shroud along the central axis to a distal end forward of an outer face of the front shroud of the impeller, wherein the projection comprises one or more fins that extend, or project,radially from a circumferential surface of the projection and that extend at least partially along a length of the projection.

[0010] In some embodiments, the projection may have a generally oval shaped crosssection. In some embodiments, the one or more fins may be arranged to project radially from the circumferential surface of the projection between the two points aligned with the major axis of the oval shaped cross-section. In some embodiments, the one or more fins may project radially in a direction normal to the circumferential surface of the projection.

[0011] In some embodiments, the projection may comprise two fins, the two fins being arranged to project radially from diametrically opposing sides of the circumferential surface of the projection. In some embodiments, each of the two fins may include an apex which is substantially in line with a minor axis of the oval shaped cross section. In some embodiments, the distal end of the projection may locate within an inlet passage of a front side part when assembled for use.

[0012] In some embodiments, the projection may further comprise a plurality of grooves circumferentially spaced therearound and that extend along the length of the projection.

[0013] According to a further aspect there is provided a front side part for a centrifugal slurry pump. The front side part comprises an inlet, an outlet and a processing chamber that extends therebetween. The processing chamber has an inner side wall that comprises a plurality of recesses circumferentially spaced therearound and that extend generally in a direction between the inlet and the outlet. The plurality of recesses are inclined between 15 and 25 degrees from the inlet towards the outlet.

[0014] In some embodiments, the plurality of recesses may be inclined substantially 20 degrees from the inlet towards the outlet. In some embodiments, the plurality of recesses may be inclined in a direction that is counter to a direction of rotation of an impeller, when assembled for use. In some embodiments, the plurality of recesses may be inclined in a clockwise direction. In some embodiments, the plurality of recesses may be tapered inwardly from the inlet towards the outlet in the direction of a central axis through the front side part.

[0015] According to a further aspect there is provided a centrifugal slurry pump assembly comprising a pump casing having a front side part as described above and arranged at an inlet to the pump casing. The assembly further comprises a centrifugal slurry pump impeller as described above. The centrifugal slurry pump impeller is arranged such that the projection is at least partially disposed within the processing chamber of the front side part, the centrifugal slurry pump impeller being configured to rotate about the central axis relative to the pump casing.

[0016] In some embodiments, the centrifugal slurry pump impeller may be configured to rotate in an anti-clockwise direction about the central axis relative to the pump casing.Description of the Figures

[0017] The accompanying drawings facilitate an understanding of the various embodiments.

[0018] Figure 1 is a cross-sectional side elevation view of a centrifugal slurry pump including an impeller and inlet according to one embodiment of the present invention;

[0019] Figures 2a, 2b and 2c are front, side projection, and side views, respectively, of the impeller depicted in Figure 1 ;

[0020] Figure 3 is a front perspective view of the centrifugal pump impeller and inlet of Figure 1;

[0021] Figure 4 is a cross sectional side view along Section A-A of Figure 3; and

[0022] Figure 5 is a front view of the centrifugal pump impeller and inlet of Figure 1.Detailed Description

[0023] Referring to Figure 1 of the drawings, a centrifugal slurry pump 100 is shown having a rotatable impeller 50 positioned at least in part within a pumping chamber 30 that is provided inside the main liner 60 of the pump 100. The impeller 50 is operatively connected to a drive shaft (not shown) whereby, in use, the impeller 50 is able to rotate about a rotation axis X-X, or central axis.

[0024] The rotation of the impeller 50 causes the fluid (or solid-liquid mixture) being pumped to pass from a pipe connected to an inlet 10 through the pumping chamber 30 and out of the pumping chamber 30 via the discharge outlet 12. The impeller 50 comprises a front 52 and back 54 shroud, and circumferentially spaced pumping vanes 58 extending in a spaced apart relation to one another around the central axis of rotation X-X, with passageways 59 between the adjacent pumping vanes 58. The pumping vanes 58 extend from the back shroud in a direction generally in line with the axis of rotation X-X of the slurry pump impeller 50. The inner face of the back shroud 54 is generally in a plane which is at right angles to the axis of rotation X-X.

[0025] Referring to Figures 2 to 5, the impeller 50 comprises a projection 40 that extends from the back shroud 54 along the central axis of rotation X-X to a distal end 41 forward of an outer face 53 of the front shroud 52 of the impeller 50 and, at least in part, into the inlet passageway 23 of the front side part 20 (or throatbush) of the pump 100 when assembled. The front side part 20, through which slurry enters is located at the inlet 10 of the centrifugal pump 100, and has an outlet 24 that feeds into the pumping chamber 30. A processing chamber 22 is located between the inlet 10 and outlet 24 of the front side part 20 within the inlet passageway 23 and has an inner sidewall 26 that comprises a plurality of recesses 28 that are circumferentially spaced therearound and which extend generally in a direction between an outer edge of the inlet 10 and the outlet 24.

[0026] The plurality of recesses 28 are arranged to each be inclined between 15 and 25 degrees from the inlet 10 towards the outlet 24. For example, in one form the plurality of recesses 28 may each be inclined by approximately 20 degrees between the inlet 10 and the outlet 24. In a preferred form, the incline of the recesses 28 is in a direction that is counter to a direction of rotation of an impeller 40, when assembled for use. For example, where the impeller 40 is arranged to rotate in an anti-clockwise direction, viewed from the front, the plurality of recesses 28 are inclined in a clockwise direction.

[0027] When assembled for use, the distal end 41 of the projection 40 locates within the inlet passageway 23 and processing chamber 22 of the front side part 20. The inlet passageway 23 of the front side part 20 can be slightly tapered inwardly from the inlet 10 towards the outlet 24 in the direction of the central axis X-X, along with the plurality of recesses 28 that are arranged on the inner sidewall 26 thereof. This structure may assistwith funneling the fluid (or solid-liquid mixture) towards the projection 40 which assists with the processing or breaking up of large solid particles that may be present in the fluid.

[0028] The projection 40 has a generally oval cross-sectional shape, with a slightly tapered nose portion proximal the distal end 41. As a result, the distance between the side walls of the rotating projection 40 and the inner side wall 26 of the stationary processing chamber 22 varies as the projection rotates with the impeller during use. A plurality of spaced grooves 46 are circumferentially spaced around the projection 40 which extend, at least partially, along the length of the projection 40.

[0029] The projection 40 further comprises a pair of fins 42 that are arranged to project, or extend, radially away from a circumferential surface of the projection 40. The fins 42 are further arranged to extend at least partially along a length of the projection 40 from the back shroud 54 towards the distal end 41. The fins 42 project from diametrically opposing sides of the circumferential surface of the projection 40 in a direction normal to the circumferential surface of the projection 40 and between the two points aligned with the major axis M-M of the oval shaped cross- section. For example, each of the two fins includes an apex which is substantially in line with a minor axis N-N of the oval shaped cross section, and perpendicular to the major axis M-M of the oval shaped cross-section of the projection 40.

[0030] The grooves 46 of the projection 40 and the recesses 28 of the inner sidewall 26 of the front side part 20 are arranged to face each other in an opposing relationship at a distance that provides a gap allowing 1 / 3 of the inlet passage in fluid flow thereby improving the efficiency of the breaking down, grinding or crushing of the particles ofslurry that enter the processing chamber 22 via the inlet 10. As would be appreciated by one skilled in the art, in some variations not shown, the projection can comprise one or more fins with or without grooves arranged therearound.

[0031] In use, slurry is delivered to the pump 100 and enters the processing chamber 22 of the front side part 20 via the inlet 10. The projection 40 which forms part of the impeller 50 is rotating within the processing chamber 22. The tapered portion of the inner sidewall 26 of the processing chamber 22 funnels the slurry towards the outlet 22 of the processing chamber 22 and into contact with the projection 40. The configuration of the projection 40 in combination with the tapered inner sidewall 26 of the processing chamber 22 causes large solids within the slurry to be broken down to a size where they can pass out of the outlet 22 and enter and pass through the passageways 59 of the impeller 50 and the pumping chamber 30. The fins 42, in combination with the edges of the grooves 46, act as cutters on the solids in the slurry and cooperate with the recesses 28 in the inner sidewall 26 of the processing chamber 22 to break down the solids in the slurry. The shape or contour of the projection 40, and in particular the fins 42, has the effect of wedging and crushing the particles jammed between the stationary and rotating parts.

[0032] By breaking down large pieces of slurry into much smaller sizes prior to entry into the pumping chamber 30, operation of the pump 100 is improved and the risk of blockage of the impeller 50 is reduced. In addition, the components of the impeller may wear more slowly and experience improved longevity where repair and / or replacement of components is required.List of PartsCentrifugal slurry pump 100Inlet 10Discharge outlet 12Front side part 20Processing chamber 22Inlet passageway 23Outlet 24Sidewall 26Recesses 28Pumping chamber 30Projection 40Distal end 41Fins 42Spaced grooves 46Impeller 50Front shroud 52Outer face 53Back Shroud 54Hub 56Pumping vanes 58Passageways 59Main liner 60

Claims

CLAIMS1. A centrifugal slurry pump impeller including: a front shroud, a back shroud, and a plurality of pumping vanes being disposed therebetween and in a spaced apart relation to one another around a central axis, with passageways between adjacent pumping vanes, and a projection extending from the back shroud along the central axis to a distal end forward of an outer face of the front shroud of the impeller, wherein the projection comprises one or more fins that project radially from a circumferential surface of the projection and that extend at least partially along a length of the projection.

2. The centrifugal slurry pump impeller of claim 1, wherein the projection has a generally oval shaped cross-section.

3. The centrifugal slurry pump impeller of claim 2, wherein the one or more fins are arranged to project radially from the circumferential surface of the projection between the two points aligned with the major axis of the oval shaped crosssection.

4. The centrifugal slurry pump impeller of any one of the preceding claims, wherein the one or more fins projects radially in a direction normal to the circumferential surface of the projection.

5. The centrifugal slurry pump impeller of the preceding claims, wherein the projection comprises two fins, the two fins being arranged to project radiallyfrom diametrically opposing sides of the circumferential surface of the projection.

6. The centrifugal slurry pump impeller according to claim 5 when appended to claims 2 to 4 wherein each of the two fins includes an apex which is substantially in line with a minor axis of the oval shaped cross section.

7. The centrifugal slurry pump impeller of any one of the preceding claims, wherein the distal end of the projection locates within an inlet passage of a front side part when assembled for use.

8. The centrifugal slurry pump impeller of the preceding claims, wherein the projection further comprises a plurality of grooves circumferentially spaced therearound and that extend along the length of the projection.

9. A centrifugal slurry pump assembly comprising : a pump casing having a front side part arranged at an inlet to the pump casing, a centrifugal slurry pump impeller of any one of claims 1 to 9, the centrifugal slurry pump impeller being arranged such that the projection is at least partially disposed within the processing chamber of the front side part, the centrifugal slurry pump impeller being configured to rotate about the central axis relative to the pump casing.

10. The centrifugal slurry pump assembly of claim 9, wherein the centrifugal slurry pump impeller is configured to rotate in an anti-clockwise direction about the central axis relative to the pump casing.

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