Technical Field

[0001] This disclosure relates generally to centrifugal slurry pumps and components or parts for use in such pumps. Slurries are usually a mixture of liquid and particulate solids, and are commonly found in minerals processing, sand and gravel and/or dredging industry.

Background Art

[0002] Centrifugal slurry pumps generally include a pump casing comprising a main casing part and one or more side parts. The pump also comprises an outer housing which encases the pump casing. In this arrangement, the pump casing is configured as a pump liner which is typically formed from hard metals or elastomers. In an alternative arrangement, the pump assembly may be an ‘unlined’ pump assembly which does not include a pump liner, and instead the pump casing is the outer casing of the pump. An impeller is mounted for rotation within the casing about a rotation axis. The main casing part has an outer circumferential wall section with an internal surface which may be of volute form, a discharge outlet and an inlet which is at one side and coaxial with the impeller rotation axis. The impeller typically includes a hub to which a drive shaft is operatively connected and at least one shroud. Pumping vanes are provided on one side of the shroud with discharge passageways between adjacent pumping vanes. In one form of impeller, two shrouds are provided with pumping vanes being disposed therebetween. The pumping vanes include opposed main side faces one of which is a pumping or pressure side face.

[0003] Because of the abrasive nature of slurries the pump, the pump components such as the pump impeller and pump liner (or casing in the case of an unlined pump) are subjected to extreme wear which leads to a significant reduction in the operational life of these components. In particular, the main liner is subjected to wear as a result of the turbulence in the pumping chamber which causes a rough flow pattern as the slurry passes through the main liner. [0004] Often the design of pump components including the impeller and pump liner are constrained by the design and interior shape of the centrifugal slurry pump and in particular the interior shape of the outer casing of a lined centrifugal slurry pump. One approach to deal with this issue is to redesign the outer casing when redesigning the impeller or pump liner. However, this approach involves significantly more capital outlay and also often requires a change to the operational footprint of the centrifugal slurry pump which may not be available at an existing industrial site. In some situations, and in particular in the case of some unlined pump assemblies, redesign of the exterior shape of the casing may be restricted, for example, by tie bolts situated in close proximity to the casing in a manner required to secure two halves of the casing together.

[0005] The present disclosure is directed to a pump liner configuration which provides improved wear characteristics which may be compatible with existing centrifugal pump casings.

[0006] The present disclosure is also directed to a casing configuration for unlined centrifugal pumps.

Summary of the Disclosure

[0007] In a first aspect, embodiments are disclosed of a main liner for a centrifugal slurry pump, the main liner comprising: a main liner body having a circumferential portion with a centre point defined relative to the circumferential portion, wherein an inner surface of the circumferential portion defines a pumping chamber; an inlet opening formed in the main liner body for the introduction of fluid to the pumping chamber; a discharge outlet extending from the main liner body defining a fluid pathway for discharge of fluid from the pumping chamber, wherein when the discharge outlet is in a vertical orientation a horizontal axis line extending through the centre point of the circumferential portion meets the inner surface of the circumferential portion at a tangent below the discharge outlet wherein the angle a formed by the tangent and the horizontal axis line is between about 97° and about 105°. [0008] In certain embodiments, the angle a is between about 100° and about 104°. In one form, the angle a is between about 101° and about 103°.

[0009] In certain embodiments, the main liner includes a transition surface extending between the inner surface of the circumferential portion and an inner surface of the discharge outlet, the transition surface including a cutwater for separating exit flow of material in the discharge outlet from a recirculation flow in the main pumping chamber wherein a line leading from the discharge outlet along the inner surface and past a middle point of the cutwater meets the horizontal axis line at a point below the discharge outlet at an angle P of between about 79° and about 87°.

[0010] In certain embodiments, the angle P is between about 81° and about 85°. In one form, the angle P is between about 82° and about 84°.

[0011] In certain embodiments, the cutwater has a leading edge, wherein a line drawn from the leading edge of the cutwater to the centre point meets the horizontal axis line at an angle y of between about 32° and 42°.

[0012] In certain embodiments, the angle y is between about 34° and 40°. In one form, the angle y is between about 36° and 38°.

[0013] In certain embodiments, the thickness of the main liner body L taken from the leading edge of the cutwater to a junction where an exterior surface of the circumferential portion meets the exterior surface of the discharge outlet is 2.0 to 3.5 times greater than the thickness of the main liner body at a point D along a centre line passing through the centre point.

[0014] In certain embodiments, the thickness L is 2.6 to 3.2 times greater than the thickness of the main liner body at point D. In one form, the thickness L is 2.8 to 3.0 times greater than the thickness of the main liner body at point D. [0015] In certain embodiments, the thickness of the main liner body L taken from the leading edge of the cutwater to a junction where an exterior surface of the circumferential portion meets the exterior surface of the discharge outlet is about 1.0 to about 1.2 times the thickness of J wherein J is a line that passes through the body of the main liner from the inner surface of the discharge outlet, through the junction and to the inner surface of the circumferential portion meeting thickness L at right angles.

[0016] In certain embodiments the cutwater includes a rounded profile at the leading edge. In one form, the radius of the rounded profile of the cutwater is in the range of 0.09 to 0.2 x Br where Br is the radius of inlet opening.

[0017] According to another aspect embodiments are disclosed of a main liner for a centrifugal slurry pump, the main liner comprising: a main liner body having a circumferential portion with a centre point defined relative to the circumferential portion, wherein an inner surface of the circumferential portion defines a pumping chamber; an inlet opening formed in the main liner body for the introduction of fluid to the pumping chamber; a discharge outlet extending from the main liner body defining a fluid pathway for discharge of fluid from the pumping chamber, a transition surface extending between the inner surface of the circumferential portion and an inner surface of the discharge outlet, the transition surface including a cutwater for separating exit flow of material in the discharge outlet from a recirculation flow in the main pumping chamber wherein when the discharge outlet is in a vertical orientation, the main liner includes: a volute collection portion defined as the region of the main liner anti-clockwise from a point P located on the inner surface of the circumferential portion at the cutwater through to a point G located on the circumferential portion; a transition portion defined as the region of the main liner anti clockwise from the point G through to a line extending from the point P to a point H parallel to a horizontal axis on the inner surface of the discharge portion; and a discharge portion M which is the region extending from the transition portion through to the outlet of the main liner, wherein angle CA is defined as the angle formed between a radial line leading from the centre point to point P and a radial line leading from the centre point to point G wherein CA is between about 40° and 60°. [0018] In one form, the angle CA is between about 45° to 55°.

[0019] In certain embodiments, the main liner is a one piece liner composed of a metal or a metal alloy.

[0020] According to another aspect, embodiments are disclosed of a pump casing for an unlined centrifugal slurry pump, the pump casing comprising: a pump casing body having a circumferential portion with a centre point defined relative to the circumferential portion, wherein an inner surface of the circumferential portion defines a pumping chamber; an inlet opening formed in the pump casing body for the introduction of fluid to the pumping chamber; a discharge outlet extending from the pump casing body defining a fluid pathway for discharge of fluid from the pumping chamber, wherein when the discharge outlet is in a vertical orientation a horizontal axis line extending through the centre point of the circumferential portion meets the inner surface of the circumferential portion at a tangent below the discharge outlet wherein the angle a formed by the tangent and the horizontal axis line is between about 97° and about 105°.

[0021] According to another aspect, embodiments are disclosed of a pump casing for a centrifugal slurry pump, the pump casing comprising: a pump casing body having a circumferential portion with a centre point defined relative to the circumferential portion, wherein an inner surface of the circumferential portion defines a pumping chamber; an inlet opening formed in the pump casing body for the introduction of fluid to the pumping chamber; a discharge outlet extending from the pump casing body defining a fluid pathway for discharge of fluid from the pumping chamber, a transition surface extending between the inner surface of the circumferential portion and an inner surface of the discharge outlet, the transition surface including a cutwater for separating exit flow of material in the discharge outlet from a recirculation flow in the main pumping chamber, the cutwater including a leading edge, wherein when the discharge outlet is in a vertical orientation, the pump casing includes: a volute collection portion defined as the region of the pump casing anti-clockwise from a point P located on the inner surface of the circumferential portion at the cutwater through to a point G located on the circumferential portion; a transition portion defined as the region of the pump casing anti clockwise from the point G through to a line extending from the point P to a point H parallel to a horizontal axis on the inner surface of the discharge portion; and a discharge portion M which is the region extending from the transition portion through to the outlet of the pump casing, wherein angle CA is defined as the angle formed between a radial line leading from the centre point to point P and a radial line leading from the centre point to point G wherein CA is between about 40° and 60°.

[0022] Other aspects, features, and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of inventions disclosed.

Brief Description of the Drawings

[0023] Notwithstanding any other forms which may fall within the scope of the method and apparatus as set forth in the Summary, specific embodiments of the method and apparatus will now be described, by way of example, and with reference to the accompanying drawings in which:

[0024] Figures 1 and 2 are schematic partial cross-sectional side elevations of typical centrifugal slurry pump assemblies;

[0025] Figure 3 is an isometric view from one side of a main pump liner in accordance with an embodiment;

[0026] Figure 4 is an isometric view from the other side of the main pump liner depicted in Figure 3;

[0027] Figure 5 is a cross section of an existing main pump liner, the cross section taken through the midpoint between the two opposed sides of the main pump liner and perpendicular to the rotation axis of the pump; [0028] Figure 6 is a cross section of a main pump liner in accordance with an embodiment, the cross section taken through the midpoint between the two opposed sides of the main pump liner and perpendicular to the rotation axis of the pump;

[0029] Figure 7 is a close up detailed view of a cross section of the cutwater of the main pump liner depicted in Figure 6

[0030] Figure 8 is a cross section of a cross section of an existing main pump liner, the cross section taken through the midpoint between the two opposed sides of the main pump liner and perpendicular to the rotation axis of the pump;

[0031] Figure 9 is a cross section of a main pump liner in accordance with an embodiment, the cross section taken through the midpoint between the two opposed sides of the main pump liner and perpendicular to the rotation axis of the pump;

[0032] Figure 10 is an isometric view of an unlined centrifugal slurry pump; and

[0033] Figure 11 is a schematic partial cross-sectional side elevation of a typical unlined centrifugal slurry pump assembly.

Detailed Description of Specific Embodiments

[0034] Referring to Figures 1 and 2 of the drawings, there is generally illustrated slurry pump apparatus 100 comprising a pump 10 and pump housing support in the form of a pedestal or base 112 (only partially shown) to which the pump 10 is mounted. Pedestals are also referred to in the pump industry as frames. The pump 10 generally comprises an outer casing 22 that is formed from two side casing parts or sections 23, 24 (sometimes also known as the frame plate and the cover plate) which are joined together about the periphery of the two side casings sections 23, 24. The pump 10 is formed with side openings one of which is an inlet hole 28 there further being a discharge outlet hole 29. The arrangement is such that when in use in a process plant, the pump is connected by piping to the inlet hole 28 and to the outlet hole 29, to facilitate for example pumping of a mineral slurry.

[0035] The pump 10 further comprises a pump inner liner 11 arranged within the outer casing 22 and which includes a main liner 12 and two side liners 14, 30. The side liner (or back liner) 14 is located nearer the rear side of the pump 10 (that is, nearest to the pedestal or base 112), and the other side liner (also referred to as a front liner or throatbush) 30 is located nearer the front side of the pump. The slurry pump apparatus 100 is referred to as a ‘lined’ centrifugal slurry pump apparatus. In a lined slurry pump apparatus 100, the main liner 12 and two side liners are configured to fit within the cavity defined by the inside surface of the outer casing 22 provided by the two side casing sections 23, 24.

[0036] As shown in Figures 1 and 2 the two side casing parts 23, 24 of the outer casing 22 are joined together by bolts 27 located about the periphery of the casing parts 23, 24 when the pump is assembled for use. In some embodiments the main liner 12 can also be comprised of two separate parts which are disposed within the side casing parts 23, 24 and brought together to form a single main liner, although in the example shown in figure 1, the main liner 12 is made in one-piece, shaped similar to a car tyre. The liner 11 may be made of materials such as rubber, elastomer or of metal.

[0037] When the pump is assembled, the side openings in the main liner 12 are filled by or receive the two side liners 14, 30 to form a continuously-lined pumping chamber 42 disposed within the pump outer casing 22. A seal comprising a seal chamber housing 114 and seal adaptor 115 encloses the side liner (or back liner) 14 and is arranged to seal the space or seal chamber 118 between drive shaft 116 and the pedestal or base 112 to prevent leakage from the back area of the outer casing 22. The seal chamber housing takes the form of a circular disc section and an annular section with a central bore, and is known in one arrangement as a stuffing box 117. The stuffing box 117 is arranged adjacent to the side liner 14 and extends between the pedestal 112 and a shaft sleeve and packing that surrounds the shaft 116.

[0038] As shown in Figures 1 and 2 an impeller 40 is positioned within the main liner 12 and is mounted or operatively connected to the drive shaft 116 which is adapted to rotate about a rotation axis X-X. A motor drive (not shown) is normally attached by pulleys to an exposed end of the shaft 116, in the region behind the pedestal or base 112. The rotation of the impeller 40 causes the fluid (or solid-liquid mixture or slurry) being pumped to pass from a pipe which is connected to the inlet hole through the pumping chamber 42 which is within the main liner 12 and the side liners 14, 30 and then out of the pump via the discharge outlet hole.

[0039] As shown, the front liner 30 (or throatbrush) includes a cylindrically- shaped intake section 32 through which slurry enters the pumping chamber 42 when the pump is in use. The intake section 32 has an intake passageway 33 therein with a first, outermost end 34 operatively connectable to a feed pipe (not shown) and a second, innermost end 35 adjacent the chamber 42. The front liner 30 further includes a side wall section 15 which mates in use with the main liner 12 to form and enclose the chamber 42, the side wall section 15 having an inner face. The back liner 14 comprises a disc-like body having an outer edge which mates with the main liner and an inner face.

[0040] The impeller 40 includes a hub 41 from which a plurality of circumferentially spaced pumping vanes 43 extend. An eye portion 47 extends forwardly from the hub 41 towards the passage 33 in the front liner 30. The impeller 40 further includes a front shroud 50 and a back shroud 51, the vanes being disposed and extending therebetween and an impeller inlet 48. The hub 41 extends from the back liner 14. In figure 2 the shrouds are arranged in planes which are generally at right angles to the rotation axis. In figure 1 the front shroud is inclined with respect to the axis.

[0041] The front and back shrouds include an inner face, an outer face and a peripheral edge portion. The front shroud includes an inlet, and the vanes 43 extend between the inner faces of the shrouds. The shrouds are generally circular or disc-shaped when viewed in elevation; that is in the direction of rotation axis X-X (figure 1).

[0042] As illustrated in Figure 2, each shroud has a plurality of auxiliary or expelling vanes on the outer faces thereof, there being a first group of auxiliary vanes 60 on the outer face of the front shroud and a second group of auxiliary vanes 61 on the outer face of the back shroud. In the embodiment of figure 1 there are auxiliary vanes on the front shroud only.

[0043] Figures 10 and 11 show an unlined centrifugal slurry pump 100. As can be seen in Figure 11, the pump assembly 100 is of a similar construction to the lined centrifugal slurry pump assembly described with respect to Figures 1 and 2 with the key difference being that the unlined slurry pump assembly 100 of Figure 11 does not include a main liner 12. Rather, the outside casing 22 of the pump assembly provides the inner surface of the pumping chamber and provides a similar function to the main liner of a lined centrifugal slurry pump. As is shown in Figures 10 and 11, like features have been provided with the same reference numerals as used in Figures 1 and 2.

[0044] With reference to Figures 3, 4, 6 and 7 there is illustrated a main slurry pump liner 120 which comprises a main liner body 122 which includes a pumping chamber 124 having opposed sides 137, 138 (Figures 3&4) each having an opening 139, 140 therein (Figures 3&4). The main liner body 122 further comprises a circumferential portion 141 which includes a centre point Q defined relative to the circumference of the circumferential portion 141 of the main liner body 122. The circumferential portion may be of volute form. The centre point Q may, or may not be coaxial with the rotation axis X- X of the impeller and drive shaft of the centrifugal slurry pump. In Figure 6, the centre point Q of the main liner body 122 is aligned with the rotation axis X-X of the impeller and drive shaft.

[0045] The circumferential portion 141 has an inner surface 144 which contains the pumping chamber 124. The main liner body 122 further includes a discharge outlet 150 having a discharge passageway 151 with an inner surface 152 which is in fluid communication with the pumping chamber 124. The discharge passageway 151 extends generally from the pumping chamber 124 and terminates at a discharge outlet port 154.

[0046] Figure 6 is a cross section of a main pump liner 120 where the cross section is taken through the midpoint between the two opposed sides 137, 138 of the main pump liner 120 and perpendicular to the rotation axis of the centrifugal slurry pump when in use. In this figure, the main liner body 122 depicts the discharge outlet 150 extending from the main liner body 122 in a vertical orientation. Otherwise stated, the discharge outlet is in an orientation where the discharge outlet 150 is extending upwards and away from a surface upon which the slurry pump is positioned in use. In such a vertical orientation, a horizontal axis line Y-Y extending through the centre point Q of the circumferential portion 141 meets the inner surface 144 of the circumferential portion 141 at a tangent on the circumferential portion and below the discharge outlet at an angle a of between about 97° and about 105°. In a preferred embodiment the angle a may be between about 100° and about 104°. In a more preferred embodiment the angle a may be between about 101° and about 103°. In still a further preferred embodiment the angle a may be about 102°.

[0047] The main liner 120 may further include a transition surface 180 extending between the inner surface of the circumferential portion 144 and an inner surface 152 of the discharge outlet 150, the transition surface 180 including a cutwater 185 for separating exit flow of material in the discharge outlet 150 from a recirculation flow in the main pumping chamber 124. As depicted in Figures 6, a line A-A leading from the discharge outlet 150 along the inner surface 152 of the discharge outlet and past a middle point of the cutwater 185 meets the horizontal axis line Y-Y at a point below the discharge outlet 150 may be at an angle P of between about 79° and about 87°. In a preferred embodiment the angle P may be between about 81° and about 85°. In a more preferred embodiment the angle P may be between about 82° and about 84°. In still a further preferred embodiment the angle P may be about 83°.

[0048] The cutwater 185 of the main liner 122 may have a leading edge 190 which is at the point of the cutwater 185 which splits and separates the exit flow of material and the recirculation flow of material in the main liner 120 during operation.

[0049] Referring to Figure 6, a line B-B drawn from the leading edge 190 of the cutwater 185 to the centre point Q meets the horizontal axis line Y-Y at an angle y of between about 32° and 42°. In a preferred embodiment the angle y may be between about 34° and about 40°. In a more preferred embodiment the angle y may be between about 36° and about 38°. In still a further preferred embodiment the angle y may be about 37°.

[0050] The main liner 120 in accordance with this disclosure has an increased thickness at the cutwater 185 due to the orientation of the discharge outlet 150 relative to the pumping chamber 124 of the main liner 120 as described herein. Specifically, the thickness of the main liner body L taken from the leading edge of the cutwater 190 to a junction 195 where an exterior surface of the circumferential portion 141 meets the exterior surface of the discharge outlet 150 may be 2.0 to 3.5 times greater than the thickness T of the main liner body at a point D along a centre line passing through the centre point Q. In a preferred form, the thickness L may be 2.6 to 3.2 times greater than the thickness T of the main liner body at point D. In a further preferred form, the thickness L may be 2.8 to 3.0 times greater than the thickness T of the main liner body at point D. It yet a further preferred form, the thickness T of the main liner body at point D may be about 2.9 times greater than the thickness T of the main liner body at point D.

[0051] Figure 7 depicts a close up view of the cross-section of the cutwater 185 shown in Figure 6. Thickness L taken from the leading edge of the cutwater 190 to a junction 195 where the exterior surface of the circumferential portion 141 meets the exterior surface of the discharge outlet 150 meets thickness J at right angles which is a line that passes through the body of the main liner from the inner surface 152 of the discharge outlet 150 to the inner surface 144 of the circumferential portion 141. The thickness L may be about 1.0 to about 1.2 times the thickness of J. In addition, the thickness of the wall of the discharge outlet adjacent the junction 195 may be about 1.7 to about 2.8 times the thickness of the wall of the discharge outlet located on the other side of the discharge outlet.

[0052] Figure 5 provides a cross section of an existing main pump liner where the cross section is taken through the midpoint between the two opposed sides of the main pump liner and perpendicular to the rotation axis of the pump. The view of the existing main pump liner shown in Figure 5 is the equivalent cross section to the view of the main liner in accordance with an embodiment of the present disclosure shown in Figure 6. [0053] The existing main pump liner of Figure 5 is designed to fit within the cavity formed by the outer casing 22 of a pump apparatus 100 as depicted in Figures 1 and 2. The existing main pump liner of Figure 5 has a circumferential portion 141 with an outside surface 225 with the same dimensions as the outside surface 225 of the circumferential portion of the main pump liner 120 in accordance with an embodiment of the present disclosure shown in Figure 6.

[0054] As shown in Figure 5, the existing pump liner has a horizontal axis line Y-Y extending through the centre point Q of the circumferential portion 141 which meets the inner surface 144 of the circumferential portion 141 at a tangent below the discharge outlet at an angle a equal to 94°. The existing pump liner of Figure 5 also includes a line A-A leading from the discharge outlet 150 along the inner surface 152 of the discharge outlet and past a tangential point of the cutwater 185 that meets the horizontal axis line Y-Y at a point below the discharge outlet 150 at an angle P of 90°. The existing pump liner of Figure 5 further includes a line B-B drawn from the leading edge 190 of the cutwater 185 to the centre point Q meets the horizontal axis line Y-Y at an angle y of 44°. These dimensions provide that the existing pump liner shown in Figure 5 includes a thickness at the cutwater of the main liner body L taken from the leading edge of the cutwater to a junction where an exterior surface of the circumferential portion 141 meets the exterior surface of the discharge outlet 150 which is 1.7 times greater than the thickness T of the main liner body at a point D along a centre line passing through the centre point Q.

[0055] A further embodiment of a main pump liner in accordance with the present disclosure is depicted in Figure 9 where the main liner 120 includes a volute collection portion P-G defined as the region of the main liner 120 moving from a point P located on the inner surface of the circumferential portion 141 at the cutwater 185 anti-clockwise around the centre point Q through to a point G located on the circumferential portion 141; a transition portion G-PH which is defined as the region of the main liner 120 moving anti clockwise from the point G through to the region defined by a line extending from point P on the circumferential portion 141 to a point H on the inner surface of the discharge portion; and a discharge portion M which is the region extending from the transition portion through to the discharge outlet port 154 of the main liner 120, wherein angle CA is defined as the angle formed between a radial line leading from the centre point Q to point P and a radial line leading from the centre point to point G. In this embodiment angle CA is between about 40° and 60°. In a preferred form, angle CA is between about 45° to 55°.

[0056] In comparison, a prior art liner is shown in Figure 8 where the volute collection portion P-G, the transition portion G-PH and the discharge portion M are identified. As can be seen, the transition portion G-PH of the liner depicted in Figure 9 in accordance with the present disclosure encompasses the same angular span as the prior art liner depicted in Figure 8. However point G of the liner depicted in Figure 9, is no longer parallel to the outlet P-H or the horizontal axis whilst the transition region is contoured to maintain a smooth transition to the discharge section and maintaining a primarily tangential orientation with the radius Br of the main liner openings and to the discharge outlet port 154. This provides that the position of the transitional portion G-PH in the liner of Figure 9 has been shifted enabling the cutwater to be enlarged. The shift between the collection portion P-G and the transitional portion G-PH is defined by the change in the orientation of the circumferential portion 141 in the collection portion P-G increasing in the transition portion G-PH from point G onwards. In the prior art liner shown in Figure 8, this occurs at a later point (when point G is in line with the horizontal axis).

[0057] In accordance with a further embodiment, and with reference to Figure 9, the radius of the cutwater 185 at the leading edge 190 may be in the range of 0.09 to 0.2 x Br, where Br is the radius of the openings 139, 140 in the side of the main liner 120. Typically, the radius of the openings is slightly greater than the radius of the impeller which is fitted within the main liner during use. It was found that it is preferred that the radius of the cutwater at the leading edge is in this range. Whilst it may seem feasible to extend the cutwater 185 further into the transition region G-PH to a sharper point, during use and particularly when pumping abrasive slurries, the point of a cutwater so arranged would shear away quickly. The preferred radius enables the cutwater to be extended while providing the desired effect of extending the wear life of this region of the pump liner.

[0058] As illustrated with reference to the main liners in accordance with embodiments described herein and with reference to Figures 6, 7 and 9 it was identified that when the orientation of the discharge outlet 150 is altered relative to the pumping chamber 124 of the main liner 120, and in particular when the values of the angles a, P and/or y as defined herein were adjusted as herein described, that the thickness of the cutwater was significantly increased, whilst maintaining the same dimensions of the outside surface 225 of the circumferential portion as the existing pump liner. It was also found that the pump liner so adjusted included substantially the same internal capacity as well as substantially the same pumping efficiency as the existing pump liner.

[0059] The increase in the thickness of the cutwater advantageously provides the main pump liner as herein described with increased wear protection at the cutwater and therefore longer operational life than the existing pump liner with the same dimension of the outside surface of the circumferential portion.

[0060] It was also identified that when the orientation of the discharge outlet is altered relative to the pumping chamber of a pump casing for an unlined centrifugal pump assembly, and in particular when the values of the angles a, P and/or y as defined herein were adjusted as herein described, that the thickness of the cutwater of the pump casing was significantly increased, whilst maintaining substantially the same internal capacity and pumping efficiency as before.

[0061] In the foregoing description of preferred embodiments, specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "top" and "bottom", "front" and "rear", "inner" and "outer", "above", "below", “vertical”, "upper" and "lower" and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

[0062] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0063] In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of’. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear.

[0064] In addition, the foregoing describes only some embodiments of the invention(s), and alterations, modifications, additions and/or changes can be made thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictive.

[0065] Furthermore, invention(s) have been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention(s). Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.

Table of Parts

Pump apparatus 100

Pump 10

Pedestal 112

Outer casing 22

Side casing sections 23, 24

Inlet hole 28

Discharge outlet hole 29

Inner liner 11

Main liner 12, 120

Side liners (front and back) 14, 30

Bolts 27

Pumping chamber 42

Seal chamber housing 114

Cover plate 115

Seal adapter 116

Stuffing box 117

Impeller 40

Delivery section 32

Passage 33

Outer end 34

Inner end 35

Sidewall section 15

Inner face 16

Lip 38

Hub 41

Pumping vanes 43

Eye portion 47

Rotation axis X-X

Auxiliary vanes 60

Auxiliary vanes 61 Main liner body 122

Pumping chamber 124

Opposed sides 137, 138

Openings 139, 140

Circumferential portion 141

Centre point Q

Inner surface 144

Discharge outlet 150

Discharge passageway 151

Discharge passageway inner surface 152

Discharge outlet port 154

Horizontal axis line Y-Y

Intersection point 210

Transition surface 180

Cutwater 185

Line (inner discharge surface) A-A

Leading edge 190

Line (leading edge to centre) B-B

Thickness of cutwater L

Junction (exterior surface) 195

Thickness of casing at D T

Outside surface of circumferential portion 225

Thickness (discharge to pumping chamber) J

Volute collection portion P-G

Transition portion G-PH

Discharge portion M

Angle of transition portion CA

Radius of impeller/Liner opening Br

Cutwater radius CR