Centrifugal slurry pump impeller

Abstract

An impeller for a centrifugal slurry pump, the impeller including a front and back shroud with each shroud having an outer peripheral edge and sharing a central axis. The impeller including a plurality of pumping vanes extending between the front and back shroud and spaced apart to form a passageway between adjacent pumping vanes. Each pumping vane having a leading edge near the central axis and a trailing edge near the outer peripheral edge. Each vane has a thickness profile near the leading edge which includes a first thickness near the back shroud and a second thickness near the front shroud, the second thickness being greater than the first thickness.

Description

[0001] CENTRIFUGAL SLURRY PUMP IMPELLER

[0002] TECHNICAL FIELD

[0003]

[0001] The present invention relates to centrifugal slurry pumps, and in particular an impeller for a centrifugal slurry pump.

[0004] BACKGROUND ART

[0005]

[0002] Centrifugal slurry pumps are well known and widely used in the mining industry to pump slurry. Slurry enters the pump through a suction port, and an impeller accelerates the slurry under the effect of centrifugal force out through an outlet. The slurry can cause rapid wear on pump parts such as the impeller and the side liners. As the slurry enters the impeller the interaction between the moving pumping vanes and rapid turn causes wear on the pumping vanes which in turn causes leakage and damage to other parts of the pump such as the front side liner, or throatbush.

[0006]

[0003] WO 2016 / 040979 addresses wear concern on the front side liner, or throatbush, by providing unique profiled expeller / auxiliary vanes on the outer surface of the impeller's front shroud. The impeller 10 shown in Figure 1 includes a front shroud 12, a back shroud 14, and pumping vanes 16 extending between the shrouds 12, 14. The pumping vanes 16 have a constant width between the front and back shrouds 12, 14 and a leading edge 16a that leans, or slopes, forward toward a central axis Y-Y. Figure 2 is a section cut in a plane parallel with the leading edge 16a. The forward slope of the leading edge 16a helps to pick up slurry near the inlet, or eye 20 of the impeller 10. The front shroud 12 includes expeller / auxiliary vanes 18 which have a step feature 22 toward an outer periphery of the shroud 12 aimed at reducing wear.

[0007]

[0004] It is among the objects of embodiments of the present invention to overcome or mitigate one or more of the above disadvantages or other disadvantages of the prior art, or to provide a useful alternative.

[0008] SUMMARY OF THE INVENTION

[0009]

[0005] This summary is provided to introduce a selection of concepts that are further described in the detailed description below. This summary is not intended to identify indispensable features of the claimed subject matter, nor is it intended for use as an aid in limiting the scope of the claimed subject matter.

[0010]

[0006] According to an aspect there is provided an impeller for a centrifugal slurry pump. The impeller includes a front shroud having an outer peripheral edge and a back shroud having an outer peripheral edge. The shrouds share a central axis. The impeller includes a plurality of pumping vanes extending between the front and back shrouds. The pumping vanes are spaced apart around the central axis to form a passageway between adjacent pumping vanes. Each pumping vane has a leading edge near the central axis, a trailing edge near the outer peripheral edge and opposed side faces extending radially from the leading edge to the trailing edge. Each vane has a leading edge thickness profile near the leading edge which includes a first thickness, measured between opposed side faces near the back shroud and a second thickness, measured between opposed side faces near the front shroud, wherein the second thickness is greater than the first thickness.

[0011]

[0007] In one example, the leading edge thickness profile is defined by a vane thickness angle measured between opposed side faces at or near the leading edge. Preferably, the vane thickness angle is about 10 - 20 degrees.

[0012]

[0008] In one example, the second thickness, near the front shroud is 1.25 to 1.5 times the first thickness, near the back shroud.

[0013]

[0009] In one example, the thickness profile of the vane is constant from the leading edge to the trailing edge.

[0014]

[0010] In another example, each vane has a trailing edge thickness profile near the trailing edge, which includes a first thickness near the back shroud and a second thickness near the front shroud, wherein the first and second thicknesses are substantially similar at the trailing edge of the vane.

[0015]

[0011] In another example, each vane has a trailing edge thickness profile at the trailing edge which includes a first thickness near the back shroud and a second thickness near the front shroud, the second thickness being greater than the first thickness at the trailing edge of the vane.

[0016]

[0012] Preferably, the trailing edge thickness profile includes a vane thickness angle measured between the opposed main side faces of the pumping vane at the trailing edge, the vane thickness angle measured at the trailing edge being substantially equal to the vane thickness angle measured between opposed main side faces at the leading edge.

[0017]

[0013] In one example, the vane thickness angle measured between opposed main side faces is constant from the leading edge to the trailing edge.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019]

[0014] These and other examples of the present invention will now be described, with reference to the accompanying drawings, in which:

[0020]

[0015] Figure 1 shows a prior art impeller;

[0021]

[0016] Figure 2 shows a section view of the prior art impeller in Figure 1 cut near the leading edge of the pumping vane and parallel to the leading edge of the pumping vane;

[0022]

[0017] Figure 3 shows an impeller according to one example of the present disclosure;

[0023]

[0018] Figure 4 shows a section of the impeller in Figure 3 cut near the leading edge of the pumping vane and parallel to the leading edge of the pumping vane;

[0024]

[0019] Figure 5 shows an impeller according to another example of the present disclosure;

[0025]

[0020] Figure 6 shows a partial view of the impeller in Figure 5; and

[0026]

[0021] Figure 7 shows a partial view of the impeller in Figure 3.

[0027] DESCRIPTION OF EMBODIMENTS

[0028]

[0022] Figures 3 and 4 show an impeller 100 in accordance with the present disclosure. The impeller 100 is for a centrifugal slurry pump for pumping slurry in the minerals processing industry. The impeller 100 is rotatable about a central axis X-X and includes a hub 116, a front shroud 110, a back shroud 112 and pumping vanes 114 extending from the shrouds 110, 112. A drive shaft (not shown) is operatively connected to the hub 116 for rotation. Each pumping vane 114 includes a leading edge 114a near the central axis X-X, or eye, 120 of the impeller 100 and a trailing edge 114b near a peripheral edge 136, 138 of each shroud 110, 112. Each pumping vane 114 has a length measured from the leading edge 114a to the trailing edge 114b. The front shroud 110 of the impeller 100 includes expeller / auxiliary vanes 118 that extend radially from the central axis X-X. In use, the impeller 100 is operatively connected to the drive shaft and is adapted to rotate about the central axis X-X, causing the slurry to move out through a discharge outlet (not shown). The back shroud 112 is nearest the drive shaft, or drive side of the pump, and the front shroud 110 is nearest the suction side of the pump.

[0029]

[0023] Each pumping vane 114 includes opposed main side faces 122, 124, and each side face 122, 124 on adjacent vanes 114 together with an inner surface 128, 130 of the front and back shrouds 110, 112 defines passageways 126. Each passageway 126 includes a blended region 132, 134 that acts as a transition surface between each of the opposed main side faces 122, 124 and the inner surfaces 128, 130 of the front and back shrouds 110, 112 respectively. The inner surface 130 of the back shroud 112 is generally planar and at a right angle to the central axis X-X. As the slurry enters the impeller 100, it impacts the moving vanes 114, and the impact causes wear at the inlet, or eye, 120 near the leading edge 114a of the pumping vanes 114. Additionally, vortices are formed by the slurry, and fine particles in the slurry can penetrate the blended regions 134 between the vanes 114 and the front shroud 110.

[0030]

[0024] At or near the leading edge 114a of the vanes 114 the opposed main side faces 122, 124 diverge linearly from the blended region 132 of the back shroud 112 toward the front shroud 110, making the pumping vane thickness increase toward the front shroud 110. In other words, each pumping vane 114 has a thickness profile between the back shroud 112 and the front shroud 110 defined by a first thickness tl near the blended region 132 of the back shroud 112 and a second thickness t2 near the blended region 134 of the front shroud 110, and the first thickness tl is smaller than the second thickness t2. The thickness profile of the vanes 114 at the leading edge 114a includes a vane thickness angle a measured between the opposed main side faces 122, 124 normal to a centreline of the vane 114. The thickness profile of the pumping vane 114 may extend for 25% of the length of the pumping vane 114, or 50% of the length of the pumping vane 114, or 75% of the length of the pumping vane 114 or the entire length of the pumping vane 114. The thickness of the pumping vane 114 between the front and back shrouds 110, 112 may increase by 1.25 to 1.5 times depending on the angle a which may be between 10 and 20 degrees.

[0031]

[0025] As shown in Figure 7, the thickness profile, may blended into a generally uniform thickness between the front and back shrouds 110, 112 towards the trailing edge 114b of the vane 114. In other words, at the trailing edge 114b of the vane 114 the second thickness t2' is about the same as the first thickness tl', and the vane thickness angle a decreases to a draft angle, such as 2- 3 degrees. This example addresses the wear seen at the leading edge 114a of the vane 114 by adding more material only near the front shroud 110 near the leading edge 114a. It will be understood that there will be a slight thickness difference at the trailing edge 114b to allow for removal of tooling during the casting process, typically no more than 2 or 3 degrees.

[0032]

[0026] In use, slurry pump impellers often suffer severe material loss at the blended region 134 where the leading edge 114a of the pumping vane 114 meets the front shroud 110. The wear is caused by strong vortex action of the slurry, or fluid solid combination, in the blended region 134. This wear not only causes material loss on the pumping vane 114, but also at the sealing area between the impeller 100 and the front side liner, or throatbush, eventually causing the pump to fail. Advantageously, providing more material on the pumping vane 114 at the leading edge 114a near the front shroud 110 creates rounder and thicker curvature which reduces the vortex action that causes the wear and extends the life of the impeller 100. Additionally, the slope created by the thickness variation at the leading edge 114a helps to move solids away more effectively from the blended region 134 which helps to reduce wear.

[0033]

[0027] The foregoing describes only some embodiments of the inventions, and alterations, modifications, additions and / or changes can be made thereto without departing from the scope of the disclosed embodiments, the embodiments being illustrative and not restrictive. For example, as shown in Figures 5 and 6, the pumping vane 114 may have a constant thickness profile from the leading edge 114a to the trailing edge 114b. In other words the angle a between the opposed main side faces 122, 124 is constant from the leading edge 114a to the trailing edge 114b, and the thickness t2' at the trailing edge 114b is generally equal to the thickness t2 near the leading edge 114a.

[0034]

[0028] Additionally, the leading edge 114a of the pumping vanes 114 may be sloped, or angled away from the central axis X-X or be parallel to the central axis X-X. LIST OF REFERENCE NUMERALS

[0035] Impeller 10 Inner surface 128, 130

[0036] Front shroud 12 Blended region 132, 134

[0037] Back shroud 14 Edge of front shroud 136

[0038] Pumping vane 16 Edge of back shroud 138

[0039] Impeller 100 Thickness at leading edge tl, t2

[0040] Front shroud 110 Thickness at trailing edge tl', t2'

[0041] Back shroud 112

[0042] Pumping vane 114

[0043] Leading edge 114a

[0044] Trailing edge 114b

[0045] Hub 116

[0046] Expeller / auxiliary vanes 118

[0047] Inlet / eye 120

[0048] Main side face 122, 124

[0049] Passageways 126

Claims

CLAIMS1. An impeller for a centrifugal slurry pump, the impeller including: a front shroud having an outer peripheral edge; a back shroud having an outer peripheral edge, wherein the front and back shrouds share a central axis; and a plurality of pumping vanes extending between the front and back shroud and spaced apart to form passageways between adjacent pumping vanes, each pumping vane having a leading edge near the central axis, a trailing edge near the outer peripheral edges and opposed side faces extending radially from the leading edge to the trailing edge, wherein each pumping vane has a leading edge thickness profile defined by a first thickness near the back shroud and a second thickness near the front shroud, the second thickness being greater than the first thickness.

2. The impeller of claim 1, wherein the leading edge thickness profile is defined by a vane thickness angle measured between opposed side faces at or near the leading edge.

3. The impeller of claim 2, wherein the vane thickness angle measured between the opposed main side faces at or near the leading edge is 10-20 degrees.

4. The impeller of claim 1, wherein the second thickness is 1.25 to 1.5 times the first thickness.

5. The impeller of claim 1, wherein each pumping vane has a length measured along a vane centreline from the leading edge to the trailing edge, and the leading edge thickness profile extends from the leading edge for about 25% of the length.

6. The impeller of claim 1, wherein each pumping vane has a length measured along a vane centreline from the leading edge to the trailing edge, and wherein the leading edge thickness profile extends from the leading edge for 25-50% of the length.

7. The impeller of claim 1, wherein each vane has a trailing edge thickness profile at the trailing edge which includes a first thickness near the back shroud and a second thickness near the front shroud, the first and second thicknesses being substantially similar at the trailing edge of the vane.

8. The impeller of claim 1, wherein each vane has a trailing edge thickness profile at the trailing edge which includes a first thickness near the back shroud and a second thickness near the front shroud, the second thicknesses being greater than the first thickness at the trailing edge of the vane.

9. The impeller of claim 8, wherein the trailing edge thickness profile includes a vane thickness angle measured between the opposed main side faces of the pumping vane at the trailing edge, the vane thickness angle measured at the trailing edge being substantially equal to the thickness angle measured between opposed main side faces at the leading edge.

10. The impeller of claim 9, wherein the vane thickness angle measured between the opposed main side faces is constant from the leading edge to the trailing edge.

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