Screw hub, centrifugal screw, and solid bowl screw centrifuge

Description

[0001] The invention relates to a screw hub for a centrifuge screw, according to claim 1. Furthermore, the invention relates to a centrifuge screw according to claim 8. In addition, the invention relates to a solid-jacket screw centrifuge according to claim 9.

[0002] Solid-jacket screw centrifuges are characterized by a drum with a closed or solid jacket. The drum is rotated at high speed, allowing a multiphase mixture inside to be separated into at least a heavy phase and a light phase. The heavy phase is typically a solid phase, which is conveyed out of the drum by a screw, i.e., a centrifuge screw. For this purpose, the screw is mounted so that it can rotate within the drum and has a helix. The helix is ​​arranged around a screw hub.

[0003] The screw helix travels along the inner surface of the drum, conveying the heavier phase material to an axial end of the drum. At the end of the drum, the heavier phase material is discharged. The multiphase mixture to be clarified is therefore located between the inner surface of the drum and the screw hub.

[0004] In certain solid-wall screw centrifuges, a large pond depth is desirable, particularly for clarification reasons. However, the pond depth is limited by the diameter of the screw hub and the resulting buoyancy and sedimentation effects of the mixture or light phase being clarified.

[0005] In a common type of centrifuge screw, the solids discharge side of the screw hub is formed by a simple conical shape. The cone is, for example, designed as a closed surface.

[0006] However, this type of solids discharge section on a screw hub is not advantageous for all applications or products being processed. In some cases, this type of design can lead to unwanted blockages in the solids discharge area.

[0007] Furthermore, the consistency of the solids discharge is, for example, lumpy.

[0008] SU 561 574 A1 discloses a screw hub with an open wall structure, wherein the openings have a round or substantially triangular shape. These openings are formed in a tube. DE 18 15 199 A1 also describes a screw hub which essentially consists of a tube in which round openings are formed in a small section.

[0009] WO 2016 / 019944 A1, on the other hand, shows a cylindrical longitudinal section of a worm hub formed solely from longitudinal bars. In DE 24 50 337 A1, the entire worm hub is formed from longitudinal bars.

[0010] From CN 110 773 330 A it is known to form the solids discharge side section of a screw hub in a double-conical shape.

[0011] EP 2 551 020 A1 describes a centrifuge with a screw hub consisting of a substantially closed tube. Rectangular openings are formed in this tube only in the inlet area of ​​the screw hub.

[0012] The invention is therefore based on the objective of providing a screw hub for a centrifuge screw which, due to an improved design, has both improved flow properties and improved properties in connection with solids discharge.

[0013] Furthermore, the invention is based on the objective of providing a further developed centrifuge screw and a further developed solid-jacket screw centrifuge.

[0014] According to the invention, this problem is solved with regard to the screw hub by the subject matter of claim 1. With regard to the centrifuge screw, the aforementioned problem is solved by the subject matter of claim 8, and with regard to the solid-wall screw centrifuge by the subject matter of claim 9.

[0015] The sub-claims include at least suitable designs and further developments.

[0016] Specifically, the problem is solved by a screw hub for a centrifuge screw, wherein the screw hub has at least one cylindrical longitudinal section and a solids discharge section in the longitudinal direction. The cylindrical longitudinal section of the screw hub has an open wall structure at least in some sections, and the solids discharge section has a shape that deviates from a simple conical shape and is at least partially closed.

[0017] The longitudinal direction of a worm gear hub is essentially defined by its longitudinal axis. The longitudinal axis of a worm gear hub is the axis around which the hub rotates during use.

[0018] The longitudinal direction is preferably defined as the direction of transport of the solids discharge.

[0019] In the longitudinal direction of the screw hub, the screw hub according to the invention has at least two distinct sections. One section is the cylindrical longitudinal section. Another section is the solids discharge side section. These two sections constitute the main sections of the screw hub. The screw hub may additionally include bearing sections, particularly at the end sections or ends of the screw hub. However, the bearing sections may also be designed as subsections of the aforementioned main sections or project into these main sections.

[0020] The solids discharge side section preferably forms at least one end of the screw hub.

[0021] In order to achieve improved solid discharge and a correspondingly improved quality of the solid discharge in various application areas or with different materials to be processed, the solid discharge side section has a shape that deviates from a simple conical shape and is at least partially closed.

[0022] A simple conical shape is one that, in longitudinal section through the worm hub, exhibits a frustoconical form. This frustoconical shape is formed by a closed lateral surface.

[0023] It is possible that the cylindrical longitudinal section forms one, in particular the, further end of the screw hub and / or comprises one, in particular the, further end of the screw hub.

[0024] One / the other end of the screw hub can, for example, be designed in such a way that it forms a bearing section for fastening in a drum of a solid shell screw centrifuge.

[0025] Furthermore, it is possible that the worm gear hub has such a bearing section in the area of ​​the cylindrical longitudinal section.

[0026] An open wall structure is defined in particular as one that has a large number of openings and / or a large total opening area in the relevant section of the cylindrical longitudinal segment. The opening area is understood to be the sum of all individual opening areas within the relevant segment. In other words, the opening area need not be a single, continuous opening area.

[0027] Preferably, the value of the opening area is greater than the value of the closed area. A closed area is defined as the portion of the wall structure that is sealed and does not allow any material to pass from the inside of the screw hub to the outside (or vice versa). More preferably, a closed area is defined as the sum of all individual closed areas in the relevant section.

[0028] Furthermore and / or additionally, an open wall structure is understood to be a wall structure of the screw hub that has a high proportion of openings in the radial direction. Preferably, the proportion of openings is higher than the proportion of closed surfaces. Preferably, the proportion of openings in the radial direction of the screw hub is at least 50%, more preferably at least 60%, and particularly preferably at least 65% of the total wall structure in the radial direction.

[0029] Particularly preferred is the described proportion of openings in the radial direction over the entire longitudinal extent of the open wall structure.

[0030] In a particularly preferred embodiment of the invention, the cylindrical longitudinal section consists of an open wall structure. In other words, the cylindrical longitudinal section consists entirely of an open wall structure.

[0031] Preferably, the solids discharge section has a completely closed shape. A solids discharge section is considered to have at least a partially closed shape if it is predominantly closed. In particular, a solids discharge section is not considered to have at least a partially closed shape if it consists solely of a bar structure, especially a longitudinal bar structure.

[0032] It is possible that the solids discharge section is designed as a cylindrical section and / or a cylindrical pipe section. Such a cylindrical section and / or cylindrical pipe section is understood to mean, in particular, a section that includes a pipe, the pipe being attached to the cylindrical longitudinal section, for example, by means of a connecting flange. In the following, a pipe is defined as a cylindrical section that is at least partially hollow.

[0033] By using such a design for the solids discharge side of the screw hub, a screw hub and thus a centrifuge screw of this type can be provided that is particularly advantageous for reducing constrictions in the direction of solids discharge. Such constrictions are known in solid-bowl screw centrifuges. These are known to occur in the area of ​​the transition from a cylindrical longitudinal section to a discharge section.

[0034] The drum of a solid-bowl screw centrifuge typically has a conical shape in this section. By forming a cylindrical section and / or a cylindrical pipe section, an increased volume is provided in the area of ​​the solids discharge or in the final residence path of the transported solids within the drum. This reduces known bottlenecks. As a result, high solids loads can be transported within a specific timeframe during the processing of a material or medium to be separated.

[0035] A further advantage of designing the solids discharge section as a cylindrical section and / or cylindrical pipe section is that the solids are in a relaxed state. This also applies to solids that may have already been compressed during processing. Such a relaxed solid is less likely to form lumps at the discharge point and is in a free-flowing form.

[0036] Due to the reduced forces acting on the solids discharge section, this design is particularly wear-resistant. Constructing a cylindrical pipe section as the solids discharge section is suitable for processing slurries with a high mineral content. The processing of abrasive media can also be carried out particularly gently with this design of the solids discharge section.

[0037] Since the worm hub additionally has a cylindrical longitudinal section which at least partially, preferably completely, forms an open

[0038] Due to its wall structure, the snail hub can immerse itself in a pool of the mixture circulating in the drum, which is to be clarified, without any adverse effects occurring during immersion due to buoyancy forces.

[0039] Furthermore, no sedimented particles adhere to the cylindrical longitudinal section of the screw hub, which would otherwise sink from the mixture to be clarified towards the inside of the drum. Instead, the sedimented particles flow outwards to the outside of the drum.

[0040] Using the screw hub according to the invention, a large pond depth can be constructed in conjunction with a solid-jacket screw centrifuge, while simultaneously achieving improvements in the area of ​​solids discharge.

[0041] It is possible that the cylinder section and / or cylindrical pipe section is designed in such a stepped manner that the cylinder section and / or the cylindrical pipe section has at least two sections with different diameters in the longitudinal direction of the screw hub.

[0042] Using such a stepped design, a further reduction in the unwanted formation of bottlenecks can be achieved. At the same time, the solid material being transported and discharged can be further depressurized.

[0043] The at least two sections of the cylinder section and / or the cylindrical pipe section are preferably arranged such that the section with the smaller or smallest diameter is spaced further away from the cylindrical longitudinal section than the section of the cylinder section and / or the cylindrical pipe section with the larger or largest diameter. The stepped design of the cylinder section and / or the cylindrical pipe section preferably proceeds such that the diameters of the sections are reduced stepwise towards the end face of the screw hub belonging to the section on the solids discharge side.

[0044] In a further embodiment of the invention, it is possible that the solids discharge side section has a double truncated cone shape.

[0045] The double truncated cone shape is preferably designed such that the imaginary bases of two truncated cones lie against each other.

[0046] The frustoconical shape is preferably designed such that the largest diameter of the frustoconical shape is neither formed on a connecting section to the cylindrical longitudinal section nor on an end face of the screw hub associated with the solids discharge side section.

[0047] A first cover surface of a first truncated cone of the double truncated cone shape is arranged in a connecting section and / or a transition area to the cylindrical longitudinal section of the screw hub.

[0048] A second cover surface of a second truncated cone of the double truncated cone shape is formed on the end face associated with the solids discharge side section or pointing in the direction of this end face.

[0049] It is possible that the truncated cones forming the double-truncated cone shape have the same height. In such an embodiment of the invention, the double-truncated cone shape is axially symmetrical. The axis of symmetry is formed in the region of the overlapping bases of the two truncated cones.

[0050] In a further embodiment of the invention, the truncated cones forming the double frustum shape have different heights. Preferably, the truncated cone adjacent to the cylindrical longitudinal section has a lower height than the second truncated cone, which points towards the end face of the worm hub.

[0051] By forming the solids discharge side section in the shape of a double truncated cone, fine particles can be separated even better from materials to be processed that are already separated in phases.

[0052] Forming a double truncated cone as the solids discharge side section is particularly suitable for processing materials with a high organic content.

[0053] Due to the double-truncated cone shape, centrifuge screws can be manufactured with a reduced screw helix height and / or a reduced baffle plate height. This allows for material savings in the screw helix and any baffle plates that may need to be incorporated.

[0054] In addition, the aforementioned components of a centrifuge screw or a solid-jacket screw centrifuge, namely a screw helix and / or a baffle plate, are subjected to less stress than is the case in connection with the formation of simple conical shapes in the area of ​​the solids discharge side section.

[0055] Furthermore, when a screw hub is formed with a double-conical truncated cone shape in the area of ​​the solids discharge side section, a smoother and more stable running behavior of a corresponding solid-jacket screw centrifuge can be observed.

[0056] Due to the formation of a double-truncated cone shape, the distance between the screw and the drum of the solid-jacketed screw centrifuge is reduced. This presses the solid material, for example, against a baffle plate and increases the pressure. A separated liquid, especially separated water, can flow away along the screw without pressure due to this design.

[0057] In one embodiment of the invention, the open wall structure is formed, at least in sections, from longitudinal bars. Such longitudinal bars can be stabilized, for example, by means of transverse discs. An opening structure with a plurality of openings for the passage of a medium to be processed is formed between the longitudinal bars. An interior space of the longitudinal section is formed, which is kept free of obstructions, thereby improving the flow characteristics in the region of the cylindrical longitudinal section.

[0058] The same advantages are achieved in the embodiment of the open wall structure according to the invention, which is formed at least section by a plurality of web elements that define a plurality of openings. The web elements are arranged radially outside the cylindrical longitudinal section with respect to a longitudinal axis and form a circumference of the longitudinal section, wherein two web elements each form a web pair that defines at least one opening, wherein both web elements of the web pair extend longitudinally and transversely to the longitudinal direction, or wherein a first web element of the web pair extends longitudinally and a second web element of the web pair extends transversely to the longitudinal direction.

[0059] Within the scope of the invention, the longitudinal direction corresponds to a direction parallel to the longitudinal axis of the worm hub. The direction transverse to the longitudinal direction, or the transverse direction, is understood to be a direction along the circumference of the longitudinal section transverse to the longitudinal axis of the worm hub.

[0060] Due to the longitudinal and / or transverse extension of the web elements of the open wall structure, the cylindrical longitudinal section, and thus the screw hub, exhibits increased torsional and bending stiffness. This is particularly advantageous when using the screw hub in a solid-wall screw centrifuge with a large longitudinal extension, as the overall system thereby exhibits increased stiffness.

[0061] The open wall structure with longitudinal bars offers the advantage of being a simple form of open wall structure to manufacture. The longitudinal bars used are easy to produce and assemble, and can be easily positioned and fixed relative to one another. Furthermore, this type of open wall structure is particularly wear-resistant. If the longitudinal bars are made of round rods, grinding processes are advantageously avoided, even when processing abrasive materials.

[0062] In a further embodiment of the invention, the open wall structure is formed at least partially by a tube in which a plurality of openings are formed for the passage of a medium, wherein the openings each have a longitudinal extent that is preferably greater than the width of the respective openings.

[0063] This type of open-wall structure has the advantage of being simple and inexpensive to manufacture. Essentially, the openings in the pipe wall can be formed by mechanical machining. Alternatively, the openings can be formed by laser cutting. The advantages here are that welding is significantly reduced during manufacturing and the screw hub exhibits extremely high stability.

[0064] Additionally, this design of the screw hub provides a large and continuous bearing surface, for example, for attaching a screw helix. This advantageously enables the automation of subsequent work steps in the manufacture of the screw or centrifuge screw.

[0065] The openings can, for example, have a parallelogram-like shape. Furthermore, it is possible that the openings are arranged in a spiral or helical pattern around the circumference.

[0066] Furthermore, the cylindrical longitudinal section of the screw hub can be formed in one piece. Due to this one-piece construction, only minimal stresses occur. Additionally, the concentricity of the screw hub is improved because no further machining steps are necessary.

[0067] Another subordinate aspect of the invention relates to a centrifuge screw with a screw hub according to the invention and a screw helix surrounding the screw hub.

[0068] The helical thread is preferably arranged circumferentially around the helical hub. Preferably, the helical thread extends over almost the entire or the entire longitudinal extent of the helical hub.

[0069] In other words, the screw helix is ​​preferably arranged both on the cylindrical longitudinal section of the screw hub and on the solids discharge side section of the screw hub.

[0070] Another subordinate aspect of the invention relates to a solid-jacket screw centrifuge comprising a centrifuge screw located in a drum, wherein the screw hub of the centrifuge screw is designed according to the invention.

[0071] With regard to the centrifuge screw and the solid-jacket screw centrifuge, reference is made to the advantages explained in connection with the screw hub.

[0072] Furthermore, the centrifuge screw or the

[0073] The solid-jacket screw centrifuge may alternatively or additionally exhibit one or a combination of several previously mentioned characteristics relating to the screw hub.

[0074] The invention is explained in more detail below with reference to the accompanying drawings.

[0075] The embodiments shown represent examples of how the screw hub and / or the centrifuge screw according to the invention can be designed.

[0076] These show: Fig. 1 shows a longitudinal section through a centrifuge screw with a screw hub according to a first embodiment according to the invention; and Fig. 2 shows a longitudinal section through a centrifuge screw with a screw hub according to a further embodiment according to the invention.

[0077] In the following, the same reference numbers are used for identical and equivalent parts.

[0078] In Fig. 1 A centrifuge screw 80 according to the invention is shown with a screw hub 10 according to the invention. The screw hub 10 has a cylindrical longitudinal section 11 in the longitudinal direction R and a solids discharge side section 12.

[0079] The longitudinal direction R runs essentially parallel to the longitudinal axis L of the screw hub 10. In this case, the longitudinal direction R is defined as the direction of solids transport. Solids transport occurs as shown in the diagram. Fig. 1 up to the solids discharge from right to left.

[0080] The screw hub 10 of the centrifuge screw 80 is formed from all the illustrated sections and components, with the exception of the screw helix 20. This screw helix 20 is not to be designated or defined as belonging to the screw hub 10. The screw helix 20 is to be defined as a part of the centrifuge screw 80.

[0081] In this case, the cylindrical longitudinal section 11 is longer than the solids discharge side section 12.

[0082] Based on the representation of the solids discharge side section 12, it is clear that this section does not only concern the first end face 31 of the screw hub 10, but rather is to be understood as a functional section that serves in particular to transport the solid separated from the material to be processed in the direction R of the solids discharge.

[0083] The cylindrical longitudinal section 11 has an open wall structure 40. The open wall structure 40 is formed by several longitudinal bars 41 and transverse disks 42 that stabilize these longitudinal bars 41. The longitudinal bars 41 are arranged at uniform intervals around the circumference of the screw hub 10 in its longitudinal direction R, i.e., parallel to the longitudinal axis L.

[0084] The open wall structure 40 can also be formed by web elements, specifically web pairs, as explained in the preceding description.

[0085] Alternatively, the open wall structure is possible if it is formed by a tube in which a multitude of openings are formed for the passage of a medium.

[0086] The cylindrical longitudinal section 11 extends from a second end face 32 of the screw hub 10 to a connecting disc 50. The connecting disc 50 serves to connect the cylindrical longitudinal section 11 with the solids discharge side section 12.

[0087] The cylindrical longitudinal section 11 further includes a bearing section 60 for storing the centrifuge screws 80 shown in a drum (not shown) of a solid shell screw centrifuge.

[0088] In the present case, the solids discharge side section 12 is designed as a cylindrical section 45. The cylindrical section 45 is formed from solid material and has a constant outer diameter over the entire longitudinal extent of the solids discharge side section 12.

[0089] Using such a cylindrical section, a particularly wear-resistant screw hub 10 is formed, which also contributes to the relaxation of a solid to be transported in the area of ​​the solid discharge side section 12.

[0090] It is possible that the solids discharge side section 12 is formed by a cylindrical pipe section. In this case, a hollow cylinder would be formed.

[0091] The snail helix 20 extends according to the exemplary embodiment of the Fig. 1 over the entire longitudinal extent of the screw hub 10. The screw helix 20 is arranged both on the cylindrical longitudinal section 11 and on the solids discharge side section 12.

[0092] In Fig. 2 A further embodiment of a screw hub 10 or a centrifuge screw 80 according to the invention is shown. The difference to the one in Fig. 1 The illustrated embodiment relates to the solids discharge side section 12. The cylindrical longitudinal section 11 of the screw hub 10 has a design corresponding to the embodiment according to Fig. 1 consistent training.

[0093] The solids discharge side section 12 has a double truncated cone shape 70. The double truncated cone shape 70 is formed from two truncated cones, namely a first truncated cone 71 and a second truncated cone 72. The first truncated cone 71 is adjacent to or connected with the cylindrical longitudinal section 11. The second truncated cone 72, on the other hand, faces towards or encompasses the first end face 31 of the screw hub 10.

[0094] The two truncated cones 71 and 72 are arranged in such a way that the respective (imaginary) base surfaces are formed adjacent to each other in the connecting section 73.

[0095] The top surface 75 of the first truncated cone 71 and the top surface 76 of the second truncated cone 72, however, point away from each other. The top surface 75 of the first truncated cone 71 borders the cylindrical longitudinal section 11. The top surface 75 can also be an imaginary top surface. The first truncated cone 71 can be open at the top.

[0096] The top surface 76 of the second truncated cone 72, however, is actually formed. This can, for example, be formed as part of the first end face 31 of the snail hub 10.

[0097] In the present case, the two truncated cones 71 and 72 have almost identical heights H1 and H2. It is possible that the heights H1 and H2 differ in alternative embodiments of the invention.

[0098] It is also possible that a connecting disc is formed between the cylindrical longitudinal section 11 and the solids discharge-side section 12. Such a connecting disc 50 is, for example, shown in the embodiment of Fig. 1 planned.

[0099] With the help of the in Fig. 2 In the illustrated embodiment of the screw hub 10, it is possible for other internal components of a solid-jacketed screw centrifuge, such as a dust disc (not shown), to be subjected to less stress. The screw helix 20 is also subjected to less stress due to the design of the solids discharge-side section 12 than is the case, for example, with simple conical geometries.

[0100] Finally, it should be noted that all features mentioned in the application documents and in particular in the dependent claims, despite the formal reference made to one or more specific claims, shall be afforded independent protection, whether individually or in any combination. Reference symbol list

[0101] 10 Screw hub 11 Cylindrical longitudinal section 12 Solid discharge side section 20 Screw helix 31 First end face of screw hub 32 Second end face of screw hub 40 Open wall structure 41 Longitudinal bar 42 Transverse disc 45 Cylindrical section 50 Connecting disc 60 Bearing section 70 Double truncated cone shape 71 First truncated cone 72 Second truncated cone 73 Connecting section 75 Cover surface of first truncated cone 76 Cover surface of second truncated cone 80 Centrifuge screw H1 Height of first truncated cone H2 Height of second truncated cone L Longitudinal axis R Longitudinal direction

Claims

1. A screw hub (10) for a centrifuge screw (80), wherein the screw hub (10) has at least one cylindrical longitudinal section (11) in the longitudinal direction (R) and a section (12) on the side of the solids discharge, wherein the cylindrical longitudinal section (11) has an open wall structure (40) at least in sections and the section (12) on the side of the solids discharge has an at least partly closed shape, which deviates from a simple conical shape, characterized in that the open wall structure (40) is formed at least in sections by a plurality of web elements, which delimit a plurality of openings, wherein the web elements, based on a longitudinal axis, are arranged radially outside on the cylindrical longitudinal section and form a circumference of the longitudinal section, wherein two web elements in each case form a web pair, which delimits at least one opening, wherein both web elements of the web pair extend in the longitudinal direction and transversely to the longitudinal direction, or a first web element of the web pair extends in the longitudinal direction and a second web element of the web pair extends transversely to the longitudinal direction in each case.

2. The screw hub (10) according to claim 1, characterized in that the section (12) on the side of the solids discharge is formed as cylinder section (45) and / or cylindrical pipe section.

3. The screw hub (10) according to claim 2, characterized in that the cylinder section (45) and / or the cylindrical pipe section is formed to be stepped in such a way that the cylinder section (45) and / or the cylindrical pipe section has at least two sections with different diameters in the longitudinal direction (R) of the screw hub (10).

4. The screw hub (10) according to claim 1, characterized in that the section (12) on the side of the solids discharge has the shape of a double truncated cone (45).

5. The screw hub (10) according to one of the preceding claims, characterized in that the cylindrical longitudinal section (11) consists of an open wall structure (40).

6. The screw hub (10) according to one of the preceding claims, characterized in that the open wall structure (40) is formed at least in sections by a pipe, in which a plurality of openings for the passage of a medium are formed, wherein the openings each have a longitudinal extension, which is larger than a width of the respective opening.

7. The screw hub (10) according to one of the preceding claims, characterized in that the open wall structure (40) is formed at least in sections of longitudinal rods (41).

8. A centrifugal screw (80) with a screw hub (10) according to one of claims 1 to 7 and a screw flight (20) surrounding the screw hub (10).

9. A solid bowl screw centrifuge, which comprises a centrifugal screw located in a drum, wherein the screw hub (10) of the centrifugal screw is formed according to one of claims 1 to 7.