Abstract
A centrifugal separator includes a bowl with a conical part with a narrow discharge end comprising a radial surface; an end member opposite the radial surface; a number of distance members extending between the radial surface and the end member and providing outlet openings for a separated solid or heavy phase between adjacent distance members; and wear resistance members covering surfaces at the outlet opening. The wear resistance members include plate members and bushing members. The bushing members include mantle portions surrounding respective distance members. The plate members each cover a portion of the radial surface between adjacent bushing members.
Claims
1. A centrifugal separator comprising: a bowl rotatable in a direction of rotation around a longitudinal axis of rotation of said bowl, said bowl comprising a conical part with a discharge end for a separated solid or heavy phase comprising a radial surface; an end member opposite the radial surface; a plurality of distance members extending between the radial surface and the end member and providing outlet openings between adjacent distance members, said distance members having a length extending generally parallel to the longitudinal axis of rotation and an exterior circumferential surface extending around the length of the distance member; a plurality of first wear resistance members each having an inner surface covering at least a portion of the exterior circumferential surface of a respective one of said plurality of distance members and each of the plurality of first wear resistance members having an axial end surface covering a first portion of the radial surface of the bowl; and a plurality of second wear resistance members each covering a respective second portion of the radial surface of the bowl and disposed adjacent to the axial end surface of the first wear resistance members.
2. The centrifugal separator according to claim 1, wherein each of the plurality of first wear resistance member comprises a mantle that is tubular and completely circumferentially surrounds the exterior circumferential surface of a respective one of said plurality of distance members.
3. The centrifugal separator according to claim 2, wherein the mantle is positioned around the distance member thereby defining a gap therebetween and a filling material is disposed in the gap.
4. The centrifugal separator according to claim 1, wherein each of the plurality of first wear resistance members comprises a mantle that has a C-shaped cross-section perpendicular to the axial direction.
5. The centrifugal separator according to claim 1, wherein each of the plurality of second wear resistance members comprises a plate member.
6. The centrifugal separator according to claim 5, wherein the plate member comprises a concave edge, the concave edge having a lip extending therefrom, the radial surface having a corner formed on a radially innermost portion thereof, the lip extending over the corner to provide wear protection to the corner.
7. The centrifugal separator according to claim 1, wherein the axial end surface comprises a flange extending radially outward from each of the plurality of first wear resistance members.
8. The centrifugal separator according to claim 7, wherein the flange and respective ones of the plurality of second wear resistance members engage one another via overlapping edges of the flange and the second wear resistance members.
9. The centrifugal separator according to claim 8, wherein each of the plurality of second wear resistance members has a waist portion which engages the flange.
10. The centrifugal separator according to claim 1, wherein each of the plurality of second wear resistance members comprises an opening extending therethrough, a respective one of the plurality of distance members extending through the opening.
11. The centrifugal separator according to claim 1, wherein each of the plurality of second wear resistance members comprises a hole extending therethrough, the hole being configured to receive a fastening member.
12. The centrifugal separator according to claim 1, wherein at least one of the first wear resistance members and the second wear resistance members comprise tungsten carbide.
13. The centrifugal separator according to claim 1, wherein each of the plurality of distance members and each of the plurality of first wear resistance members have a non-circular cross section perpendicular to the axial direction thus preventing the respective second wear resistance member from rotating with respect to the respective distance member.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a side view of a centrifugal separator;
(2) FIG. 2A is a partial perspective view of a narrow end of a conical part of the bowl and an end member fitted with wear resistance members according to a first embodiment of the present invention;
(3) FIG. 2B is a cross sectional view of a portion of the conical part of the bowl and an end member of FIG. 2A taken across line 2B-2B;
(4) FIG. 2C is a cross sectional view of a portion of the conical part of the bowl and an end member of FIG. 2A taken across line 2C-2C to illustrate the corner pieces;
(5) FIG. 2D is another embodiment of the narrow end of the conical part of the bowl and an end member of FIG. 2A illustrating conical distance members and bushing members;
(6) FIG. 3A is a cross section of a bushing member fitted on a distance member and taken across line 3A-3A of FIG. 2A;
(7) FIG. 3B is a cross section of a bushing member fitted on a distance member and taken across line 3B-3B of FIG. 2A;
(8) FIG. 4A is a partial perspective view of a narrow end of a conical part of the bowl and an end member fitted with wear resistance members according to a second embodiment of the present invention;
(9) FIG. 4B is a cross sectional view of a portion of the conical part of the bowl and end member of FIG. 4A taken across line 4B-4B;
(10) FIG. 4C is a perspective view of a second embodiment of a bushing member;
(11) FIG. 5 is a perspective view of a second embodiment of a plate member,
(12) FIG. 6 is a plan view of the plate member of FIG. 5;
(13) FIG. 7 is a cross-sectional view of section along line 7-7 in FIG. 6;
(14) FIG. 8 is a perspective view of plate members of the second embodiment assembled into a ring;
(15) FIG. 9A is partial perspective view of a narrow end of a conical part of the bowl and an end member fitted with wear resistance members according to a third embodiment of the present invention;
(16) FIG. 9B is a perspective view of the bushing member and plate assembly of FIG. 9A; and
(17) FIG. 10 is a cross sectional view of the bushing member of FIG. 9B taken across line 10-10 in FIG. 9A.
DETAILED DESCRIPTION
(18) A rotating body 1 of a centrifugal separator or decanter centrifuge schematically shown in FIG. 1 includes a bowl 2 and a screw conveyor 3 which are mounted on a shaft 4 and are rotatable in use around a horizontal axis 5 of rotation. The axis 5 of rotation extends in a longitudinal direction of the bowl 2. Further, the rotating body 1 has a radial direction 5a extending perpendicular to the longitudinal direction.
(19) For the sake of simplicity, directions up and down are used herein as referring to a radial direction towards the axis 5 of rotation and away from the axis 5 of rotation, respectively.
(20) As shown in FIG. 1, the bowl 2 includes a base plate 6 provided at one longitudinal end of the bowl 2. The base plate 6 has an internal side 7 and an external side 8. The base plate 6 is provided with a number of liquid phase outlet passages 9 having external openings in the external side 8 of the base plate. Furthermore, the bowl 2 has solid phase discharge openings 10 (e.g., outlets) provided at an end opposite to the base plate 6.
(21) As shown in FIG. 1, the screw conveyor 3 includes inlet openings 11 for feeding a feed, e.g., slurry to the rotating body 1. The slurry includes a light or liquid phase 12 and a heavy or solid phase 13. During rotation of the rotating body 1 as previously described, separation of the liquid phase 12 and solid phase 13 phases is obtained. The liquid phase 12 is discharged through the outlet passages 9 in the base plate 6, while the screw conveyor 3 transports the solid phase 13 towards the solid phase discharge openings 10 through which the solid phase 13 is eventually discharged.
(22) As shown in FIG. 1, inside surfaces 17A and 17B of the bowl 2 are tapered radially inward thereby defining a conical part 17D of the bowl. The inside surfaces 17A and 17B taper radially inward along a length of the conical part 17D, towards the solid phase discharge openings 10 and terminate proximate a narrow end 15 of the inside surfaces 17A and 17B. As shown in FIGS. 1 and 2, an exterior portion 16 of the bowl 2 has a circular cylindrical cross section.
(23) The area around the solid phase discharge openings or outlet openings 10 is shown in more detail in FIG. 2A, which shows the narrow end 15 of the bowl 2 in greater detail. The narrow end 15 has a radial surface 19 extending radially inward from the exterior portion 16. The radial surface 19 is covered by wear resistance members according to a first embodiment of the present invention, as described herein. An end member 21 of the centrifugal separator has a flange portion 23 with through holes 25 for bolts, not shown, and distance members 27 (one distance member 27 is shown in FIG. 2A in a cut away portion of thereof, also see FIGS. 2B, 3A and 3B) extending between the radial surface 19 and the flange portion 23 an axial length L1 (see FIG. 2B). The bolts (not shown) are inserted in the holes 25 and through holes 28 in the distance members 27 to be fastened to the radial surface 19 thereby mounting the end member 21 on the radial surface 19. The distance members 27 may be integral with the radial surface 19 or with the end member 21, or they may be separate elements.
(24) As shown in FIG. 2A, the outlet openings 10 are located between the distance members 27. In particular, the outlet openings 10 have a generally rectangular cross section defined between four corners 10A, 10B, 10C and 10D. Flow of the solid phase 13 through the outlet openings 10 is designated by the arrows marked SD. The outlet openings 10 shown in FIG. 2A are fitted with wear resistance members, such as those of the first embodiment.
(25) As best shown in FIGS. 2B and 3A, in the first embodiment, bushing members are generally designated by the element number 29. The bushing members 29 have a tubular mantle portion 31 surrounding the respective distance member 27 such that an inner surface 31Z covers an exterior circumferential surface 27X of the distance member, as shown in FIG. 3A. Though not circular (i.e., are not right circular cylinders), the distance members 27 are cylindrical (i.e., have a surface traced by a straight line moving parallel to a fixed straight line and intersecting a fixed planar closed curve) such that a width W1 (see FIG. 2B) at any circumferential axial line is equal along that axial line. The tubular mantle portion 31 has a cylindrical shape complementary to that of the distance member 27. However, as shown in FIG. 2D, the distance members 27 and accordingly the tubular mantle portions 31 are conical, preferably slightly conical having a taper angle . For the first embodiment, the tubular mantle portion 31 (including the flange 33) are also referred to as the first wear resistance members, plate members 35 are also referred to as the second wear resistance members. The first wear resistance members the second wear resistance members and the corner members 41 are collectively referred to herein as wear resistance members.
(26) As shown in FIGS. 2A, 2B and 3B, the tubular mantle portion 31 of the bushing member 29 carries at the end adjacent the radial surface 19 a flange 33 that has an axial end surface 33D abutting and covering a portion of the radial surface 19. Thus, the flange 33 extends radially outward from the tubular mantle portion 31, as best shown in FIG. 3B.
(27) As shown in FIGS. 2A and 2B, plate members 35 are fitted onto the radial surface 19, between adjacent bushing members 29. The plate members 35 have an hourglass-shape with a waist portion 37. As best shown in FIG. 2B, the adjacent edges 39 of the flanges 33 and the plate members are stepped, whereby the edges of the flanges 33 are overlapping the edges of the plate members 35. For example, the flange 33 has an upper lip surface 39E that extends outwardly from a recess surface 39D and terminates at and edge surface 39F of the flange 33. The plate members 35 have a lower lip surface 35E that extends outwardly from a recess surface 35D and terminates at and edge surface 35F of the plate member 35. Thus, the flanges 33 are secured to the plate members 35 due to the overlap of the upper lip surface 39E over the lower lip surface 35E and the hourglass-shape of the waist portion 37. The bushing members 29 are fit between the radial surface 19 and the flange portion 23. Preferably cement, or a like filler, is used to fill any gaps between the wear resistance members and the adjacent surfaces of the bowl including the end member and especially the distance members. Such filler assist the securing of the wear resistance members and avoid rattling.
(28) The embodiment shown in FIG. 2A further illustrates separate corner elements 41 attached by means of glue for the wear protection of the internal edge (e.g., corner) of the radial surface 19.
(29) FIGS. 4A, 4B, 4C, 5, 6, 7 and 8 show a second embodiment of wear resistance members that are configured to be fitted at the outlet openings 10 as an alternative to the bushing members 29 and the plate members 35 shown in FIGS. 2A, 2B, 2C, 2D, 3A and 3B.
(30) The second embodiment includes cylindrical bushing members 43 (also referred to as first wear resistance members) and plate members 45 (also referred to as second wear resistance members) that are collectively referred to herein as wear resistance members. In one embodiment the bushing members are conical to correspond to the shape of the distance members 27, similar to that shown and described with reference to FIG. 2D for the first embodiment. The wear resistance members of the second embodiment are adapted to the same centrifugal separator as the wear resistance members of the first embodiment.
(31) As shown in FIG. 4C, the cross-section of the bushing member 43 of the second embodiment is identical to the cross-section of the tubular mantle portion of the bushing member 29 of the first embodiment, as shown in FIGS. 3A and 3B. This prevents the tubular bushing member 43 from rotating around the distance member 27. The bushing member 43 has projections 47a, 47b extending from one end thereof. The projections 47a, 47b are received in recesses, not shown, in the flange portion 23. As shown in FIG. 4B the bushing member 43 has an inner surface 43Z that covers the exterior circumferential surface 27X of the distance member 27. As shown in FIG. 4B, the bushing member 43 has an axial end 43K that engages and covers a portion of the radial surface 19.
(32) As shown in FIG. 8, the plate members 45 are adapted to form a ring covering the radial surface 19 as best shown in FIG. 4A. The plate member 45 has an opening 49 shaped to receive the bushing member 43 with a loose fit. The plate member 45 has a hole 51 with a recessed edge 51a for receiving a fastening member such as a bolt (not shown).
(33) The plate member 45 has a concave edge 53 with an extension 55 rising from the plane of the surface 57 abutting the radial surface 19 when the plate member has been mounted, whereby the extension 55 extends around the internal edge of the radial surface 19 to protect said internal edge. Accordingly, the extension 55 is similar to the separate corner elements 41 of the first embodiment as illustrated in FIGS. 2A and 2C.
(34) At either end of the concave edge 53 the plate member has stepped edge 59, 61, whereby the stepped edges are oppositely stepped so that an edge 59 adjacent the hole 51 of one plate member 45 may overlap an edge 61 adjacent the opening 49 of a neighbouring plate member 45b when the plate members 45 are mounted to form a ring on the radial surface 19.
(35) Mounting of the plate members 45 is performed as follows: The plate members 45 are assembled into a ring as shown in FIG. 8 on a flat steel ring (not shown). The steel ring comprises openings corresponding to the openings 49 for the distance members 27 to extend through and holes corresponding to the holes 51, but having a smaller diameter. The plate members 45 are fastened to the steel ring by means of, e.g., glue and the steel ring is fastened to the radial surface 19 of the narrow end of the bowl of the centrifugal separator by means of bolts with a head so shaped that the bolt is tightened against the rim of the hole in the steel ring without abutting, but only overlaying, the recessed edge 51a of the hole 51 in the plate member. The heads of the bolts are accommodated in the holes to be protected from wear. Overlaying the recessed edge 51a the head of the bolt secures the plate member to prevent its removal in case the glue should fail. The stepped edge 59 of one plate member secured by a bolt through the hole 51 will secure the opposite stepped edge 61 of the neighbouring plate member 45b in case the glue should fail.
(36) FIGS. 9A and 9B illustrate four wear resistance members of a third embodiment, namely two bushing members 63 (also referred to as first wear resistance members) and two plate members 65 (also referred to as second wear resistance members). This embodiment combines various features of the first and second embodiments together with some new features. Thus, the bushing members 63 comprise a mantle portion 67 with a C-shaped cross-section. When the bushing member 63 has been mounted the mantle portion 67 will surround the distance member 27 sufficiently to prevent the bushing member 63 from being removed in a direction perpendicular to the axial direction.
(37) Moreover, the non-circular cross-section of an inner wall 69 of the bushing member 63, which corresponds to the cross-section of the distance member 27, prevents the bushing member 63 from rotating around the distance member 27. Since the mantle portion 67 has the C-shaped cross-section, only a portion of the exterior circumferential surface 27X of the distance member is covered by the inner wall 69, as shown in FIG. 9A. The inner surface 63 has a concave edge 63C. The concave edge 63C has a flange 71 (e.g., a lip) extending therefrom. The lip extends over the corner (i.e., the internal edge of the conical part adjacent the radial surface) to provide wear protection to the corner.
(38) As best shown in FIG. 10, the bushing member 63, like the bushing member 29 of the first embodiment, has a flange 71 (e.g., a lip) extending radially outward from an end thereof for abutting and covering a portion of the radial surface of the narrow end of the bowl of the centrifugal separator. The plate members 65 and the bushing members have, in this third embodiment, straight overlapping adjacent edges. Thus, the plate member 65 has stepped edges 73 and the bushing member has overlapping stepped edges 75. Thus, when mounted, the bushing members 63 secure the plate members in the axial direction and in the downward radial direction. The bushing member 63 and the plate member 65 further have, at their concave edges, respective extensions 79, 81 rising from the plane of the adjacent surfaces 83, 85, respectively. The surfaces 83, 85 engage and cover respective portions of the radial surface 19. These extensions 79, 81 correspond to the extensions 55 of the plate members 45 of the second embodiment.
(39) The straight overlapping edges 73 and 75 extend along the ends of the extensions 79, 81, and thus the bushing members 63 also secure the plate members 65 in the upwardly radial direction.
(40) It should be noted that further combinations of features of the three embodiments are possible. For example in the third embodiment it would be possible to use tubular mantle portions surrounding the distance members completely, like in the first embodiment.
(41) Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims.
