CENTRIFUGAL SCREW, AND SOLID BOWL SCREW CENTRIFUGE

Abstract

The invention relates to a centrifugal screw (10) comprising a screw hub (15) and a screw flight (20) connected to the screw hub (15), the screw hub (15) having, in the longitudinal direction (R), at least one cylindrical longitudinal portion (11) and a portion (12) at the solid-discharge end. According to the invention, an open wall structure (40) is formed only in some sections of the cylindrical longitudinal portion (11), said open wall structure (40) in the cylindrical longitudinal portion (11) extending at most over a length (LW) of 50% of the total length (GL) of the cylindrical longitudinal portion (11).

Claims

1. A centrifugal screw (10) having a screw hub (15) and a screw spiral (20) connected to the screw hub (15), wherein the screw hub (15) in the longitudinal direction (R) has at least one cylindrical longitudinal portion (11) and a portion (12) at the solid-discharge end, characterized in that in the cylindrical longitudinal portion (11), an open wall structure (40) is designed only in sections, wherein the open wall structure (40) extends in the cylindrical longitudinal portion (11) at most over a length (LW) of 50% of the total length (GL) of the cylindrical longitudinal portion (11).

2. The centrifugal screw (10) according to claim 1, characterized in that the open wall structure (40) in the cylindrical longitudinal portion (11) extends at most over a length (LW) of 45% of the total length (GL) of the cylindrical longitudinal portion (11), in particular at most over a length (LW) of 35% of the total length (GL) of the cylindrical longitudinal portion (11), particularly preferred at most over a length (LW) of 25% of the total length (GL) of the cylindrical longitudinal portion (11).

3. The centrifugal screw (10) according to claim 1 or 2, characterized in that the open wall structure (40) is designed to be spaced from both ends, in particular from both frontal sides (31, 32) of the screw hub (15), in particular to be a middle segment.

4. The centrifugal screw (10) according to claim 1, characterized in that the open wall structure (40) has a larger outer diameter (DW) than neighbouring portions (51, 51) of the screw hub (15), in particular has the largest outer diameter of the screw hub (15).

5. The centrifugal screw (10) according to claim 1, characterized in that a ratio of a/the outer diameter (DW) of the open wall structure (40) to the outer diameter (DS) of the screw spiral (20) is 0.8-0.4, in particular 0.7-0.4, particularly preferred 0.4.

6. The centrifugal screw (10) according to claim 1, characterized in that the open wall structure (40) is formed so as to have several longitudinal rods (41) running in the longitudinal direction (R).

7. The centrifugal screw (10) according to claim 1, characterized in that the open wall structure (40) is formed by a plurality of web elements delimiting a plurality of openings, wherein the web elements with respect to the longitudinal axis (L) of the screw hub (15) are arranged radially outside and form a circumference of the cylindrical longitudinal portion (11), wherein two web elements respectively form a web pair delimiting at least one opening, wherein the two web elements of the web pair extend in the longitudinal direction (R) and transversely to the longitudinal direction (R), or a first web element of the web pair respectively extends in the longitudinal direction (R), and a second web element of the web pair extends transversely to the longitudinal direction (R).

8. The centrifugal screw (10) according to claim 1, characterized in that the open wall structure (40) at least in sections is formed by a tube in which a plurality of openings is designed for the passage of a medium, wherein the openings each have a longitudinal extension which is larger than the width of the respective opening.

9. The centrifugal screw (10) according to claim 1, characterized in that the portion (12) at the solid-discharge end has a cone shape or a double truncated cone shape or is designed to be a cylindrical portion or a cylindrical tube portion.

10. The centrifugal screw (10) according to claim 1, characterized in that the open wall structure (40) is designed in an inflow area of the centrifugal screw (80), wherein an inflow tube opening of an inflow tube opens into the inflow area, wherein a baffle element, in particular a baffle disc, having an acceleration element is designed opposite the inflow tube opening, wherein the acceleration element is designed such that a medium impinging on the acceleration element can be accelerated in the direction of openings of the open wall structure (40).

11. The centrifugal screw (10) according to claim 10, characterized in that the inflow tube extends starting from the portion (12) at the solid-discharge end in the direction of the inflow area.

12. A solid bowl screw centrifuge comprising a centrifugal screw (10) located within a drum, wherein the centrifugal screw (10) is designed according to claim 1.

Description

[0134] In these is shown:

[0135] FIG. 1 a longitudinal section through a centrifugal screw according to a first exemplary embodiment; and

[0136] FIG. 2 a longitudinal section through a centrifugal screw according to another exemplary embodiment according to the invention.

[0137] The same reference numerals are used in the following for the same parts or parts having the same action.

[0138] A centrifugal screw 10 having a screw hub 15 is illustrated in FIG. 1. The screw hub in the longitudinal direction R, has a cylindrical longitudinal portion 11 and a portion 12 at the solid-discharge end.

[0139] The longitudinal direction R runs essentially in parallel to the longitudinal axis L of the screw hub 15. The longitudinal R is defined in the following case as the direction of the transport of the solid material discharge. The solid material transport according to the illustration of FIGS. 1 and 2 is performed from the right to the left side.

[0140] The centrifugal screw 80 moreover comprises a screw spiral 20.

[0141] The cylindrical longitudinal portion 11 is designed to be longer than the portion 12 at the solid-discharge end. The portion 12 at the solid-discharge end of the screw hub is to be understood to be such a functional portion which serves in particular the transport of the solid material separated from the material to be processed in the direction R of the solid material discharge.

[0142] An open wall structure 40 is only designed in sections in the cylindrical longitudinal portion. The open wall structure 40 is formed by several rods 41.

[0143] As shown in the left cross-sectional representation of FIG. 1 according to section A-A, the rods 41 are arranged distributed in even distances over the circumference of the screw hub 10, in the longitudinal direction R thereof, thus in parallel to the longitudinal axis. In the present case, the open wall structure 40 is formed of eight rods 41. The number of the rods 41 can vary and be inter alia differently configured in dependence of the diameter of the screw hub 15.

[0144] The open wall structure 40 may also be formed, as explained in the previous description, by web elements, specifically web pairs.

[0145] Alternatively, it is possible for the open wall structure 40 to be formed by a tube in which a plurality of openings is designed for the passage of a medium.

[0146] The cylindrical longitudinal portion 11 extends from a second frontal side 32 of the screw hub 15 up to the start of the portion 12 at the solid-discharge end.

[0147] The portion 12 at the solid-discharge end is formed in the present case by a cone-shape 18. The portion 12 at the solid-discharge end in addition comprises the first frontal side 31 of the screw hub 15.

[0148] Moreover, bearing portions 35 and 35′ are designed for supporting the illustrated centrifugal screw 10 in a drum (not illustrated) of a solid bowl screw centrifuge (likewise not illustrated).

[0149] The open wall structure 40 extends in the cylindrical longitudinal portion 11 at most over a length LW, wherein this length LW amounts to at most 50% of the total length GL of the cylindrical longitudinal portion 11.

[0150] In the illustrated example, the open wall structure 40 is designed between a first portion 51 of a closed wall structure and a second portion 52 of a closed wall structure. Such an embodiment, on the one hand, enables a particularly high bending and torsional rigidity. On the other hand, the screw hub 15 can immerge in the area of the open wall structure 40 into the material to be processed.

[0151] Embedding the open wall structure 40 between two portions 51 and 52 having a closed wall structure facilitates attaching the open wall structure 40 in the area of the screw hub 15.

[0152] The open wall structure 40 is spaced from the two ends or the two frontal sides 31 and 32 of the screw hub 15. The open wall structure 40 designs a kind of middle segment 50, since the middle segment 50 is designed both between two portions 51 and 52 of the cylindrical longitudinal portion 11 as well as surrounds a perpendicular A. In other words, the perpendicular A is designed in the area of the middle segment 50. The perpendicular A is the perpendicular A which is designed to be perpendicular to the longitudinal axis L and bisects the screw hub 15 with respect to its length in the longitudinal direction R.

[0153] The rods 41 of the open wall structure 40 are attached to two transverse discs 61 and 62. The first transverse disc 61 is a completely closes transverse disc 61. This prevents inter alia that the material to be processed can penetrate into the interior space of the portion 12 at the solid-discharge end. It is moreover possible for a kind of acceleration element to be designed on the transverse disc 61. This is in particular advantageous if the open wall structure 30 forms at the same time the inflow area of a screw bub 15.

[0154] The second transverse disc 62 has an opening 63. Through this opening 63, an inflow tube, for example, may be guided so that the material to be processed can flow through the open wall structure 40 to the outside into the drum interior.

[0155] In the present case, an inflow tube (not illustrated) would run starting from the second frontal side 32 in the direction of the opening 63 of the second transverse disc 62.

[0156] Alternatively, it is possible for an inflow tune to run starting from the first frontal side 31 in the direction of the open wall structure 40. In such a case, the transverse discs 61 and 62 each should be inversely designed as illustrated in FIG. 1, i.e., at the position of the illustrated first transverse disc, such a transverse disc having an opening would have to be designed.

[0157] According to the cross-sectional representation of FIG. 1, it is clear that the outer diameter DW of the open wall structure 40 has such a value that corresponds to the outer diameter DI of the neighboring portions 51 and 52 of the screw hub 15.

[0158] In FIG. 2, a further embodiment of the centrifugal screw 10 according to the invention is illustrated. The difference from the embodiment illustrated in FIG. 1 specifically concerns the realization of the open wall structure 40.

[0159] The wall structure illustrated in FIG. 2 essentially consists of rods 41 attached in the illustrated example to the portions 51 and 52 having a closed wall structure. Alternatively, an attachment to the transverse discs 61 and 62 is conceivable and possible.

[0160] In contrast to the embodiment illustrated in FIG. 1, the open wall structure 40 has a larger outer diameter DW than the neighboring portions 51 and 52 of the screw hub 15. In other words, the outer diameter DI of the neighboring portions 51 and 52 of the screw hub is smaller than the outer diameter DW of the open wall structure 40.

[0161] Due to the increased outer diameter DW, the rods 41 of the open wall structure 40 may better immerge into the material located within the drum or the pond. The ratio of the outer diameter DW of the open wall structure 40 to the outer diameter of the screw spiral 20 preferably is 0.8-0.4.

[0162] It should be pointed out in conclusion that all of the features mentioned in the application documents and in particular in the dependent claims, despite the performed formal back reference to one or several certain claims, should have an independent protection even singly or in an arbitrary combination.

LIST OF REFERENCE NUMERALS

[0163] 10 centrifugal screw [0164] 11 cylindrical longitudinal portion [0165] 12 portion at the solid-discharge end [0166] 15 screw hub [0167] 18 cone shape [0168] 20 screw spiral [0169] 31 first frontal side [0170] 32 second frontal side [0171] 35′ bearing portion [0172] 40 open wall structure [0173] 41 longitudinal rod [0174] 50 middle segment [0175] 51 first portion of closed wall structure [0176] 52 second portion of closed wall structure [0177] 61 first transverse disc [0178] 62 second transverse disc [0179] 63 opening [0180] A perpendicular [0181] DS outer diameter of screw spiral [0182] DI outer diameter of portions of the cylindrical longitudinal portion [0183] DW outer diameter of open wall structure [0184] GL total length of the cylindrical longitudinal portion [0185] L longitudinal axis [0186] LW length of open wall structure [0187] R longitudinal direction