SCREW HUB, CENTRIFUGE SCREW AND SOLID BOWL SCREW CENTRIFUGE

Abstract

The present invention relates to a screw hub (70) for a centrifuge screw which extends along a longitudinal axis and has at least one longitudinal portion (72) having an opening structure (74), wherein the opening structure (74) is formed by a plurality of connecting elements (75) which delimit a plurality of openings (77) for the passage of a medium, in particular a two-phase mixture, wherein the connecting elements (75) are arranged radially outside on the longitudinal portion (72) relative to the longitudinal axis and form a periphery of the longitudinal portion (72), two connecting elements (75) in each case forming a connecting piece pair (81) that delimits at least one opening (77), both connecting elements (75) of the connecting piece pair (81) extending in the longitudinal direction and crosswise to the longitudinal direction, or a first connecting element of the connecting piece pair (81) extending in the longitudinal direction and a second connecting element of the connecting piece pair (81) extending crosswise to the longitudinal direction.

Claims

1. A screw hub (70) for a centrifuge screw, which extends along a longitudinal axis and has at least one longitudinal portion (72) having an opening structure (74), wherein the opening structure (74) is formed by a plurality of strut elements (75) delimiting a plurality of openings (77) for the passage of a medium, wherein the strut elements (75) are arranged on the longitudinal portion (72) radially outside relative to the longitudinal axis and form a circumference of the longitudinal portion (72), characterized in that in each case two strut elements (75) form a strut pair (81), which delimits at least one opening (77), wherein both of the strut elements (75) of the strut pair (81) extend in the longitudinal direction and transversely to the longitudinal direction, or at least one strut element of the strut pair (81) respectively extends in the longitudinal direction, and a second strut element of the strut pair (81) extends transversely to the longitudinal direction.

2. The screw hub (70) according to claim 1, characterized in that the strut elements (75) of the strut pair (81) enclose the opening (77) partially or completely.

3. The screw hub (70) according to claim 1, characterized in that the strut elements (75) of the strut pair (81) are formed to be separated from one another, in particular as single bars (91), or to be in one piece with one another, in particular by a casting process.

4. The screw hub (70) according to claim 1, characterized in that the strut elements (75) are arranged such that the strut pair (81) is formed in the shape of a triangle.

5. The screw hub (70) according to claim 1, characterized in that the strut pair (81) comprises an inner side (87) and an outer side (88) each having a radius (89, 90) towards the opening (77), wherein the radius (89) of the inner side (87) is greater than the radius (90) of the outer side (88).

6. The screw hub (70) according to claim 5, characterized in that the strut pair (81) has a surface (87′, 88′) on the inner side (87) and on the outer side (88), respectively, wherein the surface (88′) on the outer side (88) is greater than the surface (87′) on the inner side.

7. The screw hub (70) according to claim 5, characterized in that the inner side (87) and/or the outer side (88) of the strut pair (81) are/is formed to be arched, in particular curved, and/or flat.

8. The screw hub (70) according to claim 1, characterized in that the strut pair (81) has at least two front-side connecting areas (84, 85) by means of which the strut elements (75) are connected to one another in a substance-fit manner.

9. The screw hub (70) according to claim 8, characterized in that the connecting areas (84, 85) each have at least one passage opening (86), by means of which the strut pair (81) is connected to at least one hub element (71, 72, 73), in particular a transverse disc (76), a bearing bush (73) or a screw cone (71), or to a further strut pair (81).

10. The screw hub (70) according to claim 9, characterized in that the strut pairs (81) are connected to the hub element (71, 73, 76), in particular a transverse disc (76), a bearing bush (73) or a screw cone (71), or to a further strut pair (81) in a substance-fit and/or force-fit manner.

11. The screw hub (70) according to claim 8, characterized in that the strut elements (75) of the strut pair (81) each have a cross-section (92) between the two connecting areas (84, 85), which is substantially constant along the longitudinal direction of the strut elements (75).

12. The screw hub (70) according to claim 1, characterized in that the longitudinal portion (72) has at least one strut segment formed by several strut pairs (81) interconnected in the longitudinal direction of the screw hub (70) and/or transversely to the longitudinal direction.

13. The screw hub (70) according to claim 12, characterized in that the longitudinal portion (72) has several of the strut segments (80) arranged along the longitudinal axis and being connected to one another by intermediate transverse discs (76), wherein the strut pairs (81) of the strut segments (80) being coupled to the transverse discs (76).

14. The screw hub (70) according to claim 12, characterized in that the strut pairs (81) of the strut segment (80) are arranged evenly distributed in the circumferential direction.

15. A screw hub (70) for a centrifuge screw, which extends along a longitudinal axis and has at least one longitudinal portion (72) formed by a tube (93), in which a plurality of openings (94) is formed for the passage of a medium, wherein the openings (94) each have a longitudinal extension, which is preferably greater than a width of the respective opening (94).

16. The screw hub (70) according to claim 15, characterized in that the openings (94) are formed in the circumferential direction to be helically distributed and/or have a parallelogram-like shape.

17. A centrifuge screw having a screw hub (70) according to claim 1 and a screw spiral coil (34) arranged circumferentially at the screw hub (70).

18. A solid bowl screw centrifuge having a centrifuge screw according to claim 17.

19. A solid bowl screw centrifuge having a screw hub (70) according to claim 1.

Description

[0145] The invention will be explained in more detail below by means of particulars while referring to the appended drawings. The represented embodiments illustrate examples how the screw hub according to the invention may be configured.

[0146] Shown are in:

[0147] FIG. 1 a longitudinal section of a solid bowl screw centrifuge according to the state of the art;

[0148] FIG. 2 a perspective view of a screw hub according to an exemplary embodiment according to the invention;

[0149] FIG. 3 a perspective view of a screw hub according to a further exemplary embodiment according to the invention;

[0150] FIG. 4 a perspective top views of one of the strut pairs of the screw hub according to FIG. 3;

[0151] FIG. 5 a perspective bottom view of the strut pair according to FIG. 4;

[0152] FIGS. 6a-6d several cross-sections of the strut pair according to FIGS. 4 and 5;

[0153] FIG. 7 a perspective view of a longitudinal portion of a screw hub according to a further exemplary embodiment according to the invention;

[0154] FIG. 8 a longitudinal section through the longitudinal portion of the screw hub according to FIG. 7;

[0155] FIG. 8 a cross-section through the longitudinal portion of the screw hub according to FIGS. 7 and 8; and

[0156] FIG. 9 a detailed view of one of the openings of the longitudinal portion of the screw hub according to FIGS. 7 to 9.

[0157] The same reference numerals will be used in the following for identical part and parts of identical action.

[0158] In FIG. 1, a solid bowl screw centrifuge 10 according to the state of the art is illustrated. Hereinafter, by means of FIG. 1 as an example, the basic structure as well as the basic function of a solid bowl screw centrifuge 10 will be explained, in which a screw hub 70 according to the invention can be employed. The screw hub 70 will be discussed in more detail later.

[0159] The solid bowl screw centrifuge 10 according to FIG. 1 extends substantially along a horizontal longitudinal axis 12 and has an outer housing 14, in which a drum 16 is mounted to be rotatable about the longitudinal axis 12. By rotating the drum 16 at high rotational speed, a centrifugal force can be generated within it, by mans of which a product to be clarified can be separated into a heavy phase and a light phase. For this purpose, the drum 16 is supported on a first drum bearing 18 and a second drum bearing 20.

[0160] At the drum 16, an inlet 22 for the product to be clarified, as well as an outlet 24 for the heavy phase and an outlet 26 for the light phase are formed. For rotating the drum 16, a drive 28 is formed.

[0161] The outlet 26 acts as an overflow for the light phase located radially inside within the drum, so that it exits autonomously there, if a predetermined level, the so-called pond depth 52 is reached within the drum 16.

[0162] So that the heavy phase located radially outside within the drum 16 can be discharged from the drum 16, a centrifuge screw 30 is provided within the drum 16. The centrifuge screw 30 is rotated relative to the drum 16 by means of the drive 28. Thereby, the material of the heavy phase is discharged along a cone shape at the drum 16 towards radially inside and thus to the outlet 24.

[0163] For this purpose, the centrifuge screw 30 is configured so as to have a screw hub 32 extending along the longitudinal axis 12 and being surrounded radially outside by a screw spring coil 34. The screw hub 32 thus serves the purpose of supporting the screw spiral coil 34 in the radial direction, of transmitting torque from the drive 28 to the screw spiral coil 34, and in particular of receiving tensional forces and thrust forces on this occasion. The screw hub 32 has a longitudinal portion 36 having a grid structure 56 of longitudinal bars 58, oblique struts 64 and transverse discs 60. The longitudinal portion 36 is formed cylindrically. Across the circumference of the screw hub 32, the longitudinal bars 58 are arranged in the longitudinal direction thereof, thus in parallel to the longitudinal axis 12, to be distributed at even distances.

[0164] In the conical portion 38, the screw hub 32 is formed having a shell surface 44. The shell surface 44 is substantially closed and in particular configured by means of a sheet metal or tube surface. The centrifuge screw 30 is mounted to be rotational by means of a first screw bearing 40 and a second screw bearing 42.

[0165] In FIG. 1, and inlet tube 46 may furthermore be recognized. Through this inlet tube 46, the medium to be separated gets into the solid bow screw centrifuge 10. The inlet tube 46 serves for supplying a product to be clarified centrally into an inlet region 48 to the interior of the screw hub 32.

[0166] According to FIG. 2 and FIG. 3, an screw hub 70 according to an exemplary embodiment according to the invention is shown in each case. The screw hub 70 according to the two exemplary embodiments according to the invention shown in FIG. 2 and FIG. 3 can be employed in the solid bowl screw centrifuge 10 shown in FIG. 1. In this case, the screw hubs 70 replace the screw hub 32 illustrated in FIG. 1. Alternatively, the screw hubs 70 according to FIGS. 2 and 3 can be employed in other solid bowl screw centrifuges that are not illustrated.

[0167] The screw hub 70 according to FIGS. 2 and 3 extends along a longitudinal axis and comprises a conical longitudinal portion 71, a cylindrical longitudinal portion 72, and a bearing portion 73. The portions 71, 72, 73 have the longitudinal axis as the common axis. The conical longitudinal portion 71 corresponds to the conical portion 38 of the screw hub 32 according to FIG. 1 described above. The bearing portion 73 serves for receiving a bearing, in particular the screw bearing 42 described above, in order to rotatably mount the screw hub 70. It is possible for the longitudinal portion 71 to have in further embodiments of the invention an at least partially closed shape deviating from the simple cone shape. The longitudinal portion 71 may be formed, for example, as a cylinder portion and/or a cylindrical tube portion. Furthermore, it is possible for the longitudinal portion 71 to have a double truncated-cone shape.

[0168] The cylindrical longitudinal portion 72 of the screw hub according to FIGS. 2 and 3 is arranged in the longitudinal direction between the conical longitudinal portion 71 and the bearing portion 73. The portions 71, 72, 73 are fixedly connected to one another.

[0169] The cylindrical longitudinal portion 72 is subsequently only designated as the longitudinal portion 72 for reasons of simplicity. The longitudinal portion 72 has an opening structure 74 formed by a plurality of strut elements 75 and several transverse discs 76.

[0170] The transverse discs 76 according to FIGS. 2 and 3 have a central passage opening 76′. It may be well recognized in FIGS. 2 and 3 that the opening structure 75 has a plurality of openings 77 for the passage of a medium to be clarified or to be separated, in particular of a two-phase mixture or a three-phase mixture. By the openings 77, an interior space 79 of the longitudinal portion 72 is in the installed state of the screw hub 70 in fluid connection with an interior drum space that is not illustrated. The openings 77 are formed between the strut elements 75.

[0171] The longitudinal portion 72 is formed, in particular composed, of several axially arranged strut segments 80. The strut segments 80 comprise in this case several of the strut elements 75 and several of the openings 77, which are delimited by the strut elements 75 and at least one transverse disc 76. The transverse discs 76 are provided for axially connecting the individual strut segments 80. Furthermore, the transverse discs 76 serve for stabilizing the longitudinal portion 72.

[0172] The strut elements 75 are arranged radially outside relative to the longitudinal axis of the screw hub 70 such that the strut elements 75 form a circumference of the longitudinal portion 72. The strut elements 75 are respectively combined into strut pairs 81. In other words, two strut elements 75 respectively form a strut pair 81. The respective strut segment 80 thus has several strut pairs 81. The strut pairs 81 are arranged evenly distributed in the circumferential direction. In this case, the strut pairs 81 are arranged alternatingly turned by about 180 degrees. Specifically, two adjacent strut pairs 81 are respectively arranged to be turned by about 180 degrees.

[0173] According to FIGS. 2 and 3, the two strut elements 75 of the respective strut pair 81 extend in the longitudinal direction and transversely to the longitudinal direction of the screw hub 70. In other words, the two strut elements 75 of the strut pair 81 are arranged obliquely relative to the longitudinal axis of the screw hub 70. The strut elements 75 converge towards one another in the longitudinal direction at a first end 82 of the strut pair 81. At a second end 83 of the strut pair 81, the two strut elements 74 are spaced from one another in the transverse direction, in particular in the circumferential direction. Substantially, the strut pair 81 is formed to be triangular.

[0174] In the screw hub 70 according to FIG. 2, the strut pairs 81 of the single strut segments 80 are arranged at the intermediate transverse disc 76 to be axially directly opposite. In this case, the first ends 82 each are arranged to be axially directly opposite to the respective transverse disc 76, or the second ends 83 each are arranged to be axially directly opposite to the transverse disc 76. In the longitudinal direction of the longitudinal portion 72, the strut pairs 81 of the strut segments 80 are arranged to be turned, in particular by 180 degrees, in an oppositely alternating manner.

[0175] According to FIG. 2, the strut elements 75 respectively are formed by separate longitudinal bars 91, which are in contact at the first end 82 of the strut pair 81. The strut elements 75 of the strut pairs 81 are interconnected at the first end 82. The two strut elements 75 may be interconnected in a substance-fit and/or force-fit connection. The two strut elements 81 may be interconnected by welding and/or screwing.

[0176] The opening 77 is delimited by the strut elements 75 in the region of the first end 82 of the strut pair 81. The first end 82 forms a pointed end of the strut pair 81. At the opposite, second end 83 of the strut pair 81, the opening 77 is delimited by the transverse disc 76. The strut pair 81 according to FIG. 2 this is formed to be open towards the transverse disc 76. In other words, the strut pair 81 encloses the opening only partially.

[0177] As indicated in FIG. 2, the strut elements 75 of the respective strut pair 81 have a circular cross-section. It is also possible for the strut elements 75 to have alternatively an angular, in particular square, triangular or trapezoidal and/or an oval cross-section.

[0178] In contrast to the screw hub 70 according to FIG. 2, the screw hub 70 according to FIG. 3 has strut pairs 81 formed by strut elements 75 being formed in one piece with one another. Subsequently, the screw hub 70 according to the invention will be described in more detail by means of FIGS. 3 to 6d.

[0179] The strut pairs 81 of the longitudinal portion 72 of the screw hub 70 according to FIG. 3 form a closed volume body or a closed contour completely enclosing the opening 77. The strut pairs 81 are formed by casting, in particular precision casting. In other words, the strut pairs 81 are made of one piece. Alternatively, the strut pairs 81 may also be formed by a cutting process.

[0180] The strut pairs 81 are formed to be triangular. The respective strut pair 81 has two front-side connecting areas 84, 85 interconnecting the two strut elements 75 of the strut pair 81 in a substance-fit manner. In this case, a first front-side connecting area 84 is formed at the first, in particular pointed end 82 of the strut pair 81, and a second front-side connecting area 85 is formed at the second, in particular broad end 83 of the strut pair 81. The connecting areas 84, 85 connect the strut elements 75 transversely to the longitudinal axis of the screw hub 70. The connecting areas 84, 85 have an application surface 84′, 85′ at the respective front side for being applied to the transverse discs 76. The connecting areas 84, 85 can be seen well in FIGS. 4 and 5.

[0181] It is shown according to FIGS. 4 and 5 that the first connecting area 84 has a single passage opening 86 and the second connecting area 85 has two passage openings 86. The passage openings 86 are formed in the longitudinal direction of the screw hub 70. The passage openings 86 each are formed by a bore. The respective strut pair 81 is connected to the respectively adjacent transverse disc 76 by fastening means, in particular screws and/or bolts. Alternatively, or additionally, the respective strut pair 81 may be connected to the adjacent transverse disc 76 in a substance-fit manner, for example, by welding.

[0182] The respective strut pair 81 has an inner side 87 and an outer side 88. The inner side 87 is facing towards the longitudinal axis of the screw hub 70. The outer side 88 is facing away from the screw hub 70 or, in an installation situation, is facing towards an interior drum surface. In other words, the inner side 87 is formed radially inside on the strut pair 81, and the outer side 88 is formed radially outside on the strut pair 81. The two sides 87, 88 are formed to be opposite to one another on the strut pair 81.

[0183] FIG. 4 shows a perspective top view of the strut pair 81 of the screw hub according to FIG. 3. In this case, the outer side 88 of the strut pair 81 can be seen in FIG. 4. The outer side 88 has a surface 88′ for applying a screw spiral coil. The surface 88′ forms a part of the circumference of the longitudinal portion 72. The surface 88′ is greater than a surface 87′ of the inner side 87 of the strut pair 81, as can be seen in FIG. 5. A circumferential curve towards the opening 77 is in each case formed at the inner side 87 and the outer side 88. The curves each have different radii 89, 90.

[0184] The radius 89 of the inner side 87 is greater than the radius 90 of the outer side 88. In other words, the curve on the inner side 87 is formed to be greater towards the opening 77 than the curve on the outer side 88. The inner side 87 and the outer side 88 are circumferentially rounded towards the opening 77. In other words, the radius 89 of the inner side 87 and the radius 90 of the outer side 88 are formed to be circumferential to the opening 77. As can be recognized in FIGS. 4 to 6d, the strut pair 81 on the strut elements 75 also has a radius or curve at the side facing away from the opening 77.

[0185] As can be recognized well in FIGS. 6a to 6d, the inner side 87 and the outer side 88 of the respective strut pair 81 are formed to be convex. In other words, the inner side 87 and the outer side 88 are arched. Alternatively, or additionally, it is also possible for the inner side 87 and the outer side 88 to be formed to be flat at least in some sections.

[0186] In FIGS. 6a to 6d, cross-sections of the strut pair 81 of the kind described above are shown in different longitudinal positions of the strut pair 81.

[0187] FIGS. 6a and 6d show a cross-section of the strut pair 81 in each case in a different longitudinal position of the strut elements 75, wherein the cross-sections are arranged between the two connection areas 84, 85. It can be seen in this case that the two strut elements 75 of the strut pair 81 each have a cross-section 92 being of mirror symmetry. The cross-sections 92 of the two strut elements 75 have a cross-sectional surface of equal size. The respective cross-section 92 of the two strut elements 75 is substantially constant between the two connecting areas 84, 85.

[0188] The respective cross-section 92 is circular in some sections and straight-lined in some sections. Alternatively, the cross-section 92 can be formed to be angular, in particular square, triangular or trapezoidal, and/or oval. FIGS. 6c and 6d show the transition of the strut elements 75 into the first connecting area 84 as well as the cross-sectional change associated therewith.

[0189] FIGS. 7 to 10 show a cylindrical longitudinal portion 72 of a screw hub 70 of a further exemplary embodiment according to the invention, which hereinafter will be explained in more detail.

[0190] The longitudinal portion 72 extends along a longitudinal axis and is formed by a tube 93. The tube 93 has a plurality of openings 94 for the passage of a medium, in particular a two-phase mixture or a three-phase mixture. The openings 94 are formed within the tube wall 95 and respectively form a free passage. The openings 94 each have a clear length 96, which is greater than a clear width 97 of the respective opening 94. In other words, the length of the opening 94 is greater than the width of the opening 94. The clear length 96 of the openings 94 extends in the longitudinal direction, in particular in parallel to the longitudinal axis, and the clear width 97 extends transversely to the longitudinal direction.

[0191] As can be seen in FIGS. 7 to 9, the openings 94 are formed in the circumferential direction to be helically distributed within the tube wall 95. In each case two openings 94 are spaced from one another in the circumferential direction. The distance between the two openings 94 in the circumferential direction is smaller than the clear width 97 and the clear length 96 of the openings 94. In other words, the distance between two openings 94 in the circumferential direction is smaller than the longitudinal extension of the openings 94 and the extension of the opening 94 transversely to the longitudinal axis. The same applies for the distance between two of the openings 94 in the longitudinal direction of the longitudinal portion 72. Between each of two adjacent openings 94 in the longitudinal direction of the longitudinal portion 72, a resting surface 98 for a screw spiral coil is formed. The resting surface 98 is formed outside at the tube wall 95 and surrounds it likewise helically.

[0192] According to FIG. 8 and specifically in the detail view according to FIG. 10, it can be recognized that the openings 94 are formed to have the shape of a rhombus. The openings 94 may be formed to be square, or to be circular at least in some sections. The openings 94 are formed to be rounded in corner areas. In other words, the openings 94 have radii in the corner areas. The openings 94 are equally shaped, i.e., the openings 94 have an equal passage shape. In the illustrated example, the openings 94 each have a parallelogram-like shape. In each case, two sides opposite to one another thus are formed to be parallel and of equal length.

[0193] It is also possible for the openings 94 to differ from one another in their shapes. FIG. 9 shows a cross-section through the tube 93.

LIST OF REFERENCE NUMERALS

[0194] 10 solid bowl screw centrifuge [0195] 12 longitudinal axis [0196] 14 outer housing [0197] 16 drum [0198] 18 first drum bearing [0199] 20 second drum bearing [0200] 22 inlet for the product/medium to be clarified [0201] 24 outlet for the heavy phase [0202] 26 outlet for the light phase [0203] 28 drive [0204] 30 centrifuge screw [0205] 32 screw hub [0206] 34 screw spiral coil [0207] 36 cylindrical longitudinal portion [0208] 38 conical portion [0209] 40 first screw bearing [0210] 42 second screw bearing [0211] 44 closed shell surface [0212] 46 inlet tube [0213] 48 inlet region [0214] 52 pond depth [0215] 56 grid structure [0216] 58 longitudinal bar [0217] 60 transverse disc [0218] 70 screw hub [0219] 71 conical longitudinal portion [0220] 72 cylindrical longitudinal portion [0221] 73 bearing portion [0222] 74 opening structure [0223] 75 strut elements [0224] 76 transverse discs [0225] 76′ central passage opening [0226] 77 openings [0227] 79 interior space [0228] 80 strut segments [0229] 81 strut pair [0230] 82 first end of the strut pair [0231] 83 second end of the strut pair [0232] 84 first connecting area [0233] 84′ application surface [0234] 85 second connecting area [0235] 86 passage opening [0236] 87 inner side [0237] 87′ surface of the inner side [0238] 88 outer side [0239] 88′ surface of the outer side [0240] 89 radius of the inner side [0241] 90 radius of the outer side [0242] 91 single bars [0243] 92 cross-section of the strut element [0244] 93 tube [0245] 94 openings [0246] 96 tube wall [0247] 96 clear length [0248] 97 clear width [0249] 98 resting surface