Screw Press and Method for its Maintenance

Abstract

The invention relates to a screw press (1) for dewatering sludge, whereas the screw press (1) features at least one inlet opening (2) for the sludge to be dewatered, whereas the screw press (1) features a pressing assembly, with the assistance of which the sludge is able to undergo a pressing process after passing the inlet opening (2), with which the liquid (9) present in the sludge is at least partially driven out of the sludge, whereas a pressing assembly comprises a worm shaft (4) that is movable in a rotational movement with the assistance of a drive (17) and several screen elements (5) surrounding the worm shaft (4), at least in sections, during the operation of the screw press (1), whereas the screen elements (5) feature a screen surface (6) turned towards the worm shaft (4) and a support structure (7) securing the stability of the screen elements (5), whereas the pressing assembly features at least one outlet opening (8) for the liquid (9) driven out of the sludge with the assistance of the worm shaft (4), and whereas the screw press (1) features at least one discharge opening (10) for the sludge (11) that is at least partially dewatered with the assistance of the pressing assembly. In accordance with the invention, it is proposed that the screw press (1) features at least one holding unit (12), with the assistance of which at least the support structure (7) of at least one screen element (5) can be fixed in a maintenance position, in which the screen surface (6) of the corresponding screen element (5) is spaced apart from the worm shaft (4).

Claims

1. Screw press (1) for dewatering sludge, whereas the screw press (1) features at least one inlet opening (2) for the sludge to be dewatered, whereas the screw press (1) features a pressing assembly, with the assistance of which the sludge is able to undergo a pressing process after passing the inlet opening (2), with which the liquid (9) present in the sludge is least partially driven out of the sludge, whereas a pressing assembly comprises a worm shaft (4) that is movable in a rotational movement with the assistance of a drive (17) and several screen elements (5) surrounding the worm shaft (4), at least in sections, during the operation of the screw press (1), whereas the screen elements (5) feature a screen surface (6) turned towards the worm shaft (4) and a support structure (7) securing the stability of the screen elements (5), whereas the pressing assembly features at least one outlet opening (8) for the liquid (9) driven out of the sludge with the assistance of the worm shaft (4), and whereas the screw press (1) features at least one discharge opening (10) for the sludge (11) that is at least partially dewatered with the assistance of the pressing assembly, characterized in that the screw press (1) features at least one holding unit (12), with the assistance of which at least the support structure (7) of at least one screen element (5) can be fixed in a maintenance position, in which the screen surface (6) of the corresponding screen element (5) is spaced apart from the worm shaft (4).

2-14. (canceled)

Description

[0033] Further advantages of the invention are described in the following embodiments. The following is shown, in each case schematically:

[0034] FIG. 1 a partially cut screw press in a side view,

[0035] FIG. 2 a section of a worm shaft of a screw press,

[0036] FIG. 3 the screen basket of a screw press above two holding units,

[0037] FIG. 4 the lower screen element of the screen basket shown in FIG. 3 after the removal of the upper screen basket,

[0038] FIG. 5 the screen element shown in FIG. 4 after being lowered onto the holding units and

[0039] FIGS. 6a and 6b two differently formed screen elements.

[0040] FIG. 1 shows the essential elements of a screw press 1 for dewatering sludge.

[0041] In principle, the screw press 1, which is supported by means of a corresponding support structure 7 (which, in addition to the standing legs shown, may also include various longitudinal and/or transverse beams or other frame elements), also has an inlet opening 2 for the sludge 11 to be dewatered (which may be connected, for example, to a sludge feed line 18, through which the sludge is fed).

[0042] Subsequent to the inlet opening 2, a pressing assembly extends; this comprises a worm shaft 4 that is displaceable into a rotational movement by a drive 17 (the axis of rotation is provided with the reference sign 14), which in turn preferably features an axle 19 with one or more worm spirals 3 arranged thereabove and is surrounded by a multiple number of screen elements 5, whereas the screen elements 5 together form a preferably cylindrical screen jacket 13. Of course, the screen jacket 13 may also feature conical sections, such that the cylindrical shape serves only as an example.

[0043] As can be seen in this connection from the variants of a screen element 5 shown in FIGS. 6a and 6b, regardless of its precise design, which can deviate from the variants show, this comprises a support structure 7 along with a screen surface 6 turned towards the worm shaft 4 in the installed state. Thereby, the support structure 7 may be formed, for example, by a plate featuring numerous perforations, which at the same time features the inwardly directed screen surface 6 (see FIG. 6a). Likewise, the screen surface 6 may be formed by a two-dimensional structure that features additional reinforcements or struts, which in this case form the support structure 7 (see FIG. 6b).

[0044] Through the changing, preferably decreasing, slope of the worm spiral 3 and/or its possibly changing, preferably increasing outer diameter in the direction of a discharge opening 10, the sludge is ultimately pressed together and from the inside against the screen surfaces 6 of the screen elements 5, by which it arrives at the outlet of liquid 9 through the openings (holes or slots) of the screen surfaces 6. For the support the pressing process, the dewatering device preferably has a counter-surface, for example, in the form of the pressure cone 20 that is shown. Thereby, the pressure cone 20 is located in the top end area of the worm shaft 4 and, with a corresponding outer wall, forms a ring-shaped gap that can be passed by the dewatered sludge 11. Through the adjustment of the pressure cone 20 in the axial direction of the worm shaft 4, the specified gap ultimately may be changed, and thus the counter-pressure may be adjusted during the pressing process (for this purpose, for example, one or more (for example, pneumatically operated) adjusting elements are available).

[0045] Finally, the liquid 9 is collected by one or more filtrate tanks 16 arranged below the worm shaft 4 and is guided in the direction of an outlet opening 8. There, it can be removed, for example, with the assistance of a hose assembly (not shown) or can be collected with the assistance of a collecting device.

[0046] In turn, the sludge (which is not shown for the sake of clarity, but is located between the worm shaft 4 and the screen surface 6) reaches the specified discharge opening 10 after passing through the pressing assembly. Finally, the sludge components retained by the screen surface 6 may be collected in the form of the dewatered sludge 11 and, where needed, fed to a further process.

[0047] In order to ensure that the sludge is reliably transported from the worm shaft 4 to the area of the discharge opening 10 and is thereby dewatered, it is advantageous to provide the worm spiral 3 with a scraper profile 21 in its outer area adjacent to the screen surface 6. FIG. 2 shows a cut-out of a correspondingly equipped worm shaft 4. Since, as a rule, the scraper profile 21 rests against the stationary screen surface 6, friction-induced wear occurs, such that the scraper profile 21 must be replaced at certain time intervals.

[0048] In this connection, it is known either to completely remove the worm shaft 4 or, on the other hand, to remove the screen elements 5 from the screw press 1, in order to free the worm shaft 4. In both cases, there is a need for additional space, in order to be able to put down the worm shaft 4 or the screen elements 5 next to the screw press 1.

[0049] In order to counteract this disadvantage, in accordance with the invention, it is now proposed that the screw press 1 itself has one or more holding units 12, with the assistance of which one or more screen elements 5 or at least their support structure(s) 7 (see FIGS. 6a and 6b) can be fixed in a maintenance position.

[0050] The fundamental idea of the invention is explained below with reference to the example of FIGS. 3 to 5.

[0051] In principle, the screw press 1 in accordance with the invention comprises a multiple number of screen elements 5, which together form a screen jacket 13, which surrounds the worm shaft 4, at least in sections. In the example of FIG. 3, the screen jacket 13 comprises two similar screen elements 5, which, with the assistance of means (such as screws) that are not shown, are held in a position in which they together form the screen jacket 13. The screen elements 5 can be connected to each other and/or can be detachably fastened to holding sections (not shown) of a base carrier 15 of the screw press 1. At this point, it should be pointed out that FIGS. 3 to 5 show the screen elements 5 along with a base carrier 15 of the screw press 1 exclusively and in a highly schematized manner. Of course, the screw press 1 also comprises additional elements (see FIG. 1), but such elements are not shown for reasons of clarity.

[0052] In any event, the invention now provides one or more holding units 12, which are, for example, part of the base carrier 15 of the screw press 1 or are fastened to the screw press 1 (the base carrier 15 includes, in particular, transverse and/or longitudinal struts, which form a certain frame structure). If the worm shaft 4 is now to be serviced (in particular, if its scraper profile 21 is to be replaced), the screen elements 5 must be removed spatially from the worm shaft 4. While the screen element 5 lying above in FIG. 3, or at least its support structure 7, can be easily removed (compare FIGS. 3 and 4), the removal of the screen element 5 lying below or the support structure 7 thereof is generally problematic, since, due to the worm shaft 3 present in the screw press 1, lifting is ruled out, and a downward removal generally entails the removal of the filtrate tank 16.

[0053] By contrast, by means of the holding unit(s) 12, it is now possible to lower the lower screen element 5 or at least its support structure 7 within the screw press 1 and without the removal of the worm shaft 4 or the filtrate tank 16, and to fix it in a position above the filtrate tank 16. The corresponding downwardly lowered screen element 5 is shown in FIG. 5, in which the laterally outwardly protruding sections of the support structure 7 are put down on the holding units 12 lying underneath, and are thus spatially fixed. After the maintenance work has been completed, the previously lowered screen element 5 or its support structure 7 can finally be raised again and fixed in its operating position, followed by the corresponding mounting of the upper screen element 5 or its support structure 7.

[0054] It would also be conceivable, alternatively or additionally, to fix the upper screen element 5 or its support structure 7 in a maintenance position with the assistance of or more holding units 12, whereas, in this case, the corresponding holding units 12 are to be arranged above the worm shaft 4.

[0055] This invention is not limited to the illustrated and described embodiments. Variations within the framework of the claims, such as any combination of the described characteristics, are also possible, even if they are presented and described in different parts of the description and/or the claims, or in different embodiments.

[0056] In particular, it is advantageous if the screw press comprises a cleaning device for cleaning the screen surfaces. This may comprise, for example, a tube and/or frame structure and one or more spray nozzles, which are directed from the outside against the screen elements, in order to be able to clean the screen surfaces in the counter-flow. The pipe and/or frame structure, through which a cleaning liquid (such as water) can be supplied to the spray nozzles, preferably extends around the screen jacket comprising the screen elements. For example, it would be conceivable for the cleaning device to feature two ring structures that run parallel and are spaced apart from each other in the axial direction of the worm shaft, which are connected, in a manner surrounding the screen jacket, in the axial direction by a multiple number of longitudinal struts, whereas the spray nozzles are parts of the longitudinal struts or are connected to them.

[0057] In any event, it is advantageous if the cleaning device surrounds the screen jacket in a cage-like manner and/or can be displaced in a rotational movement around the axis of rotation of the worm shaft, in order to be able to clean the entire screen surface in the counter-flow.

[0058] Furthermore, it is advantageous if the cleaning device can be disassembled into a multiple number of individual sections, such that the cleaning device can be disassembled prior to the removal in accordance with the invention of individual screen elements or their support structures, and can also be removed from their operating position (this facilitates the subsequent movement of the screen elements or their support structures in the manner described above). Preferably, the cleaning device can be disassembled into two or more similar sections, whereas the separation of the sections is preferably possible along one or more planes, which extend parallel to the axis of rotation of the worm shaft.

LIST OF REFERENCE SIGNS

[0059] 1 Screw press [0060] 2 Inlet opening [0061] 3 Worm spiral [0062] 4 Worm shaft [0063] 5 Screen element [0064] 6 Screen surface [0065] 7 Support structure [0066] 8 Outlet opening [0067] 9 Liquid [0068] 10 Discharge opening [0069] 11 Dewatered sludge [0070] 12 Holding unit [0071] 13 Screen jacket [0072] 14 Axis of rotation of the worm shaft [0073] 15 Base carrier [0074] 16 Filtrate tank [0075] 17 Drive [0076] 18 Sludge feed line [0077] 19 Axis of the worm shaft [0078] 20 Pressure cone [0079] 21 Scraper profile