Helical screw conveyor unit, worm shaft, worm extruder and method for preparing a worm shaft

Abstract

The present invention relates to a helical screw conveyor unit (100), which is formed as a replacement part for a screw-shaped or helically wound helix (240) of a worm shaft (200) of a worm extruder, and which has a base body (10) with a screw-shaped wound helix (30) to allow the helical screw conveyor unit (100) to be serviced with less maintenance effort, the upper side (16) of the mantle surface is curved concavely in a shell shape about the longitudinal axis (L) and the base body It is proposed that - the helical screw conveyor unit (100) has a radial opening (20) formed to pass a fixing area (40) of the shaft (230) of the worm axle (200), - the helical member (30) has at most half a helical turn, - the outer surface of the base body (10) has an inner surface (18) formed to rest on the fixing area (40), and - the helical screw conveyor unit (100) has at least one fixing member (34) formed to removably fix the base body (10) to the fixing area (40).

Description

[Technical field]

[0001] The invention relates to a helical screw conveyor unit as defined in the preamble of claim 1. The invention further relates to a worm shaft, in other words a conveyor worm, as defined in the preamble of claim 6.

[0002] The invention further relates to a worm extruder as defined in the preamble of claim 14.

[0003] The invention also relates to a method for preparing a worm shaft, which is configured according to the preamble of claim 15. [Background technology]

[0004] Worm shafts for use in worm extruders and the general structure of worm extruders for dewatering suspensions are described, for example, in EP 1 072 574 A, US 2017 / 08778 A and EP 2 792 739 A.

[0005] EP 1 072 574 A1 discloses a fermentation plant with a fermenter and a dewatering device in the form of a cylindrical worm conveyor, which extends along a straight axis. As shown in figures 1 to 3, a helical member with a worm shaft forms a fixed unit.

[0006] US 2017 / 08778 A1 discloses a worm extruder for dewatering an aqueous suspension of organic material. The device has an extruder chamber in which an extruder worm having a helical member is wound in a screw shape and supported for rotation about its longitudinal axis. To allow for easy and quick maintenance of the worm extruder, US 2017 / 08778 A1 teaches the provision of a highly movable screen basket divided into several parts, which allows easy access to the extruder chamber and basket replacement by one person.

[0007] EP 2 792 739 A1 discloses a double worm shaft in the extruder chamber, known for example as a cell disruption extruder, in which the helical screw conveyor unit has so-called tooth spacers on the side-by-side arranged worm shafts.

[0008] Anaerobic digestion (AD) is a bioprocess that energetically exploits organic residual materials, especially green waste, by converting them into biogas. The substrate is solubilized under anaerobic conditions in a fermenter, the fermentation material containing the waste is mixed with a liquid and the fermentation material suspension thus obtained is anaerobically fermented in the fermenter.

[0009] When the digestate resulting from the fermentation of the fermentation material suspension is dewatered using a worm extruder, the press water being separated, resulting in a press cake with an increased ratio of dry substrate to digestate. After the substrate leaves the fermenter, it is thus separated by the worm extruder into solid and liquid fermentation residues.

[0010] Essentially, the worm extruder comprises an internally located worm shaft with a screw-like helical element and a screen drum or screen cylinder covering the worm shaft. The digestion liquid to be dewatered is pumped into the screen drum via the digestion liquid inlet. The worm shaft rotates, thereby transporting the digestion liquid to the press cake outlet, against which a resistance, e.g. a counter pressure cone, is present and against which the digestion liquid is pressed. Press water exits via the press water outlet.

[0011] The further the digestate is transported forward, i.e. towards the resistance, the less volume it has and the higher the pressure on it, which forces more liquid out of the digestate, which then exits as press water. The dewatered press cake leaves the worm extruder via the press cake outlet.

[0012] When driving a worm extruder, the helical element wears over time. This wear occurs more rapidly the more pressure the helical element exerts on the digestive fluid, and is particularly pronounced in the area in front of the worm shaft, near the press cake outlet. Wear causes the pressing point to move backwards, which weakens the dewatering of the digestive fluid. Worn helical elements must therefore be repaired or replaced.

[0013] As shown in Figures 2 and 3 of US 2017 / 08778, the helical members are typically rigidly connected, e.g., welded, to the shaft of the worm shaft, so that when an individual helical member wears out, an extensive welding operation must be performed or the entire worm shaft must be replaced.

[0014] From EP 0 098 340 A1 a worm pump for transporting solid and granular materials is known. In order to arrange the end area of ​​the worm helix, which is subject to particularly high wear, in an exchangeable manner, a replaceable sleeve is provided in the end area, which can be axially pulled off from the worm shaft. To exchange the sleeve, the worm shaft must be removed from the worm pump.

[0015] Furthermore, GB 859416 A1 discloses a worm spiral conveyor with a replacement spiral member that can be plugged in as a sleeve. In order to be able to remove individual sections of the worm shaft for maintenance and repair work, the worm shaft is constructed from a number of interlocking sleeve-shaped longitudinal sections. These longitudinal sections are removably fixed to the shaft of the worm shaft by means of semicircular bracket-shaped bearings. After loosening the bearings, the sleeve-shaped longitudinal sections can be pulled axially out of the shaft of the worm shaft, for which reason the worm shaft must be able to be removed from its bearings on at least one side.

[0016] In order to avoid the need to remove and repair the blades of a worm conveyor by laborious welding after they wear out, Chinese Utility Model No. 212831025 teaches fixing the blades to the shaft with grooves and screws. The blades are separate paddle-like members that are screwed to the shaft independently of each other. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] European Patent Application Publication No. 1072574 [Patent Document 2] US Patent Application Publication No. 2017 / 08778 [Patent Document 3] European Patent Application Publication No. 2792739 [Patent Document 4] European Patent Application Publication No. 0098340 [Patent Document 5] GB Patent Application Publication No. 859416 [Patent Document 6] China Utility Model No. 212831025 Specification Summary of the Invention [Problem to be solved by the invention]

[0018] The object of the present invention is to further develop the spiral screw conveyor unit of the type mentioned at the beginning, the worm shaft of the type mentioned at the beginning, the worm extruder of the type mentioned at the beginning, and the method of the type mentioned at the beginning, so that the spiral screw conveyor unit can be serviced with reduced maintenance effort. In particular, the spiral screw conveyor unit, which is configured as a replacement part for the spiral, must be replaceable without removing the worm shaft from its bearing. Furthermore, the maintenance costs of the worm shaft must be reduced. [Means for solving the problem]

[0019] This problem is solved by a helical screw conveyor unit having the features of claim 1, by a worm shaft having the features of claim 6, by a worm extruder having the features of claim 14 and by a method having the features of claim 15. Preferred embodiments and expedient developments of the invention are characterized in the respective dependent claims.

[0020] The invention is therefore based on the fact that the helical screw conveyor unit can be mounted radially replaceably on the fixed area of ​​the shaft of the worm shaft, i.e. it can be mounted as a replaceable replacement on the rotatably supported worm shaft of the worm extruder. The invention therefore allows for a quick exchange of the helical screw conveyor unit, since the radial opening of the base body of the helical screw conveyor unit, which is designed to accommodate the shaft, allows it to be mounted radially replaceably on the shaft and can be exchanged even if the shaft is journalled at its axial end in at least one rotary bearing.

[0021] Here, "radial" refers to a direction disposed perpendicular to the longitudinal axis (L) of the worm shaft or base body of the worm shaft. Thus, radial replacement allows for efficient replacement of the helical member without removing the worm shaft from its bearing, allowing for extended operation of the worm shaft.

[0022] The shaft of the worm shaft is a bar-shaped member for transmitting a rotary motion. The helical screw conveyor unit can be mounted in a fixed area of ​​the shaft as a removable replacement part. The helical screw conveyor unit is therefore preferably configured to be removable mounted in a fixed area of ​​the above-mentioned worm shaft. Furthermore, the worm shaft is preferably suitable for mounting in a worm extruder of the above-mentioned kind.

[0023] For releasably fixing the base body of the helical member to the fixing area, the helical screw conveyor unit has at least one fixing member, so that preferably the fixing member of the helical screw conveyor unit of the above-mentioned kind is releasably connectable with a fixing means of the worm shaft of the above-mentioned kind, in particular with a fixing structure.

[0024] In a preferred embodiment, the base body is a foot member of the helical member, the foot member being arranged in a radially inner region of the helical member, the fastening member being configured for releasably fastening the foot member to the fastening region, the foot member being mountable on the fastening region in the form of a foot, and the helical member extending outwardly away from the foot member.

[0025] In order to radially and removably fix the helical member to the worm shaft in a simple manner, the fixing member can extend radially into a support area of ​​the shaft in its use position that is configured to support the helical screw conveyor unit, and a foot member placed on the fixing area can be fixed to the support area.

[0026] In a preferred embodiment, the support area of ​​the shaft has at least two helical members, with at least one fastening member associated with each helical member, and the fastening members of adjacent helical members are arranged axially and radially offset with respect to each other. The fastening members are preferably cylindrical bolts and the fastening means are screws. Alternatively, the fastening members can cooperate with the fastening means in the form of removable snap fasteners.

[0027] Preferably, the inner side of the base body of the helical screw conveyor unit of the above-mentioned kind is configured to rest on, and in particular to bear against, a fastening area of ​​the worm shaft of the above-mentioned kind, in other words the fastening area is associated with an area of ​​the worm shaft that is configured to support the base body of the helical screw conveyor unit.

[0028] In order to make it particularly easy to arrange the exchange of the helical screw conveyor unit on the worm shaft, the inner side of the base body is preferably shaped in such a way that, by placing the inner side of the base body on the fastening area of ​​the worm shaft, the orientation of the helical element of the helical screw conveyor unit on the worm shaft is determined and the radial mobility of the base body on the worm shaft is at least limited. The inner side of the base body and the fastening area therefore preferably have a shape or structure which cooperates and prevents a radial sliding or rotational movement of the helical screw conveyor unit about the shaft. In that case, a radial rotational movement of the helical screw conveyor unit about the shaft is already prevented by the cooperation of the shape or structure of the fastening area with the shape or structure of the inner side of the base body. The fastening means are then used for further or additional fastening. As will be explained in more detail below, this fastening obtained by the shape or structure can be achieved, for example, by the square shape of the fastening area. The fastening area is configured for releasably fastening a fastening member of the helical screw conveyor unit and is associated with a support area of ​​the shaft of the worm shaft, configured for supporting the helical screw conveyor unit. The fastening area has at least one fastening means, e.g. a fastening structure. Preferably, the support area has at least two fastening areas, so that preferably at least two helical screw conveyor units of the above-mentioned kind can be releasably fastened to the support area of ​​the worm shaft.

[0029] Thus, preferably, the worm shaft has at least two helical screw conveyor units. The fastening areas of the support area are then preferably configured as follows, i.e., adjacent helical screw conveyor units are respectively arranged axially and radially offset with respect to one another, for example offset in a mirror symmetrical manner. In this preferred embodiment, the worm shaft has at least two helical members arranged axially and radially offset with respect to one another. Thus, the support area has at least two fastening areas arranged axially and radially offset with respect to one another. Preferably, in this embodiment, the fastening members of adjacent helical screw conveyor units are also arranged axially and radially offset with respect to one another, for example offset by 90 degrees, for example perpendicular to one another.

[0030] The helical element has a partial helical turn, for example a quarter to a half helical turn. A number of adjacent helical elements together produce a helical turn in the shape of a helix or a screw. A number of helical turns together produce a helix wound in the shape of a screw or a helix or a screw of the worm shaft. In the present invention, the helical elements are replaceable, so that it is possible to accept an increased material wear of these helical elements compared to the worm shafts known from the prior art with non-removable helical elements, and to increase the resistance of the worm extruder, for example to enlarge or extend the counter pressure cone, in order to provide a higher power consumption for dewatering the digestive fluid.

[0031] The base body of the helical screw conveyor unit has a radial opening through which the fastening area can be guided radially, i.e. in a direction arranged perpendicular to the longitudinal axis (L) of the base body, and can be arranged on the inner side of the base body, in other words the support area can be inserted into the opening and can be accommodated in a cavity surrounded by the concave base body.

[0032] The fixing member is preferably configured to provide a complementary connection between the base body and the support region or axial body member of the shaft, for example a bolt, such as a cylindrical bolt, Alternatively, the fixing member may be configured to provide a snap connection or a clip connection.

[0033] In order to enable the base body to be supported and positioned on the support area, the inner surface of the base body is configured in a shape complementary to the fixing area, and the outer side of the base body is concavely curved and extends around the longitudinal axis, preferably in a half-shell shape or semicircular shape.

[0034] The fastening area has at least one support surface that is designed to support the base body, in particular the inner side of the base body. In order to prevent the base body from sliding on the support surface, the inner side of the mantle surface of the base body preferably has at least one contour that is designed to position the base body in a fixed manner on the fastening area and is preferably designed in a shape complementary to the fastening area or to the support surface of the fastening area. Preferably, the contour of the inner side of the base body of the helical screw conveyor unit is designed in a U-shaped or N-shaped cross section.

[0035] The helical screw conveyor unit on the worm shaft can be replaced particularly quickly and simply if the helical element is formed in such a way that by placing the inner surface of the base body on the fixing area of ​​the worm shaft, the helical element is oriented and thereby at least substantially extends the course of the helix wound in the thread or helical shape of the worm shaft.

[0036] In order to avoid radial sliding of the base body on the shaft, the inner surface of the jacket surface can be shaped, for example, at right angles, bent, curved or stepped. For example, the fastening region can be shaped in a U-shape in cross section and the inner surface of the base body in an N-shape in cross section, or vice versa.

[0037] The support area of ​​the shaft can be configured as a square, at least in the region of the fastening area. Alternatively, the fastening area can be formed by at least one recess or at least one groove in the otherwise cylindrical support area. For example, the fastening area can be a U-shaped or N-shaped recess in the otherwise cylindrical support area. In order to prevent the helical screw conveyor unit from sliding on the fastening area, the fastening area preferably has a square seat.

[0038] The helical member has a part or section of a helical revolution, preferably half a helical revolution. Alternatively, the helical member can have, for example, a third or a quarter of a helical revolution. The helical screw conveyor unit has at least one helical unit, preferably a plurality of helical units, for example four, arranged side by side with each other. To connect with the correct fit, the helical members of the helical screw conveyor units arranged side by side with each other can be welded and ground together.

[0039] Preferably, in its position of use, the fastening element extends radially through the support area and projects into the base body or through the base body of at least one helical screw conveyor unit arranged in the support area. Particularly preferably, the fastening element projects into the base body of the helical screw conveyor unit with its end projecting from the support area. Thus, in order to replace the helical screw conveyor unit, the fastening element only needs to be partially removed, for example only from the base body of the helical screw conveyor unit, but can remain fixed in the support area. This prevents the fastening element from being lost.

[0040] The worm shaft preferably comprises at least one helical screw conveyor member of the type described above, whereby the helical screw conveyor member is removably fixable to the fixing area.

[0041] Besides the helical screw conveyor member, the shaft may further comprise a cylindrical shaft body extending along a longitudinal axis with at least one shaft body helix wound in a screw shape around the shaft body. The fastening area with the support area also extending along the longitudinal axis has a smaller cross-sectional diameter compared to the cylindrical shaft body. This makes it possible to arrange the helical screw conveyor unit on the support area in such a way that the upper side of its outer surface borders flush with the cylindrical shaft body.

[0042] Preferably, the support area is arranged eccentrically, in particular in a region near the end of the cylindrical shaft body, for example at the end. The worm shaft can thus be arranged in the worm extruder in such a way that at least one replaceable helical element is arranged in the region in front of the worm extruder, near the press cake outlet. Replacing only the most worn front helical element allows for a simple, fast and less costly maintenance of the worm shaft.

[0043] In a preferred embodiment of the method of the present invention, the worm shaft comprises: at least one fastening means for fastening the first helical screw conveyor unit to the fastening area is loosened, - the first helical screw conveyor unit is removed from the worm shaft; - another helical screw conveyor unit is placed in the fixed area, and - by being removably fixed to the fixing area by means of fixing means associated with this other helical screw conveyor unit,

[0044] The invention then relates to the use of at least one worm shaft of the above-mentioned type in a worm extruder of the above-mentioned type for separating solid and liquid fermentation residues from residual material of biological origin, in particular green waste, which has been treated using a fermenter.

[0045] As already discussed above, there are various possibilities for forming and developing the teaching of the present invention in a preferred manner, for which, on the one hand, reference is made to the claims dependent on claims 1 and 6, and on the other hand, further aspects, features and advantages of the present invention are explained in more detail below, in particular by means of the embodiment made clear by figures 1 to 7. [Brief description of the drawings]

[0046] [Figure 1] 1 is a perspective view in longitudinal section of a first embodiment of a worm shaft according to the invention, on which a helical screw conveyor unit according to the invention is removably arranged and replaceable according to the method of the invention. [Diagram 2] FIG. 2 is a longitudinal sectional view of the worm shaft of FIG. [Diagram 3] FIG. 3 is a side view of the worm shaft of FIG. [Figure 4] FIG. 4 is a detailed view of the front region of the worm shaft of FIG. [Diagram 5] 5 is a cross-sectional view of the helical screw conveyor unit of FIG. 1 taken along line BB shown in FIG. [Figure 6] FIG. 6 is an exploded perspective view of the worm shaft of FIG. [Figure 7] FIG. 7 shows an embodiment of a worm extruder according to the present invention having the worm shaft of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] In Figures 1 to 7, the same or similar features, components or features have the same reference numbers.

[0048] 1 shows an embodiment of a helical screw conveyor unit 100 for a worm shaft 200. The helical screw conveyor unit 100 has a base body 10 extending along a longitudinal axis L. This base body has two end regions which extend perpendicularly to the longitudinal axis, in other words are opposite each other in the direction of the longitudinal axis. The end regions 12, 14 are connected to each other by a mantle surface on whose upper side 16, i.e. the outside, at least one helical member 30 is arranged, which winds around in a screw form.

[0049] 1 to 3, the worm shaft 200 has a plurality, for example two, of helical members 30. To connect the helical members 30 with the correct fit, they can be welded and ground together.

[0050] At least one helical member 30 has a partial, in particular a quarter to half, helical turn. The base body is concavely curved, thus curved inwards, and has a radial opening 20. In other words, the base body is hollow and extends in an arc about the longitudinal axis L. Preferably, the base body extends in a part-circular shape, for example in the shape of a half shell, about the longitudinal axis L.

[0051] The helical screw conveyor unit 100 is configured to be replaceably mounted on a worm shaft 200, preferably on the worm shaft 200 of a worm extruder 300 configured to dewater digestate obtained by anaerobic fermentation of organic material.

[0052] FIG. 6 shows an exploded perspective view of a worm shaft 200. The worm shaft has four helical screw conveyor units 100, which together form two rotating helices. The adjacent helical screw conveyor units 100 are arranged radially offset by 180° relative to one another and thus mirror-symmetrical. To removably fasten the base body 100 to the fastening area 40 of the support area 210, the helical screw conveyor units each have two cylindrical bolts 34. The fastening area 40 is formed partly in the shape of a square or rectangle. The area of ​​the support area 210 facing the helical screw conveyor units 100 or the fastening area 40 is configured as a filling body. This supports and stabilizes the support area 210. The filling body is rigidly connected to the support area 210 and can be formed, for example, integrally with the support area 210 or removably fastened to the support area 210. The filling body is concavely curved about the longitudinal axis L.

[0053] As shown in Figure 7, the worm extruder 300 has an inner worm shaft 200 with a helical member 30, 210 that winds in a screw shape extending away from the outside, and a screen drum 340 that encases the worm shaft 200. The screen drum 340 can have a swingable screen shell, which allows easy access to the worm shaft and quick replacement of screen and wear parts.

[0054] In order to be replaceably mounted on the worm shaft 200, the helical screw conveyor unit 100 is - on the outer surface of the base body 10, it has an inner surface 18 adapted to receive a support area 210 of a shaft 230; has at least one fastening member 34 configured to removably fasten said inner surface 18 to the support area 210;

[0055] The helical screw conveyor unit 100 is thus a removably fixable or replaceable member for the worm shaft 200 .

[0056] In an embodiment of the invention not shown here, the worm shaft 200 can have only the replaceable helical member 30. Alternatively, as shown in Figures 1 to 7, only a certain area of ​​the worm shaft 200, for example the front area close to the press cake outlet 350 in the position of use, can be configured as a replaceable helical screw conveyor unit 100.

[0057] 1 to 7, in addition to the replaceable helical screw conveyor unit 100, furthermore comprises a shaft 230 with a cylindrical shaft body and a shaft body helix 240 wound in a screw-like manner around the shaft 230. In the region of the cylindrical shaft body, the shaft body helix 240 is permanently connected to the shaft 230, for example being formed integrally with the shaft 230 or being welded thereto.

[0058] The support area 210 of the helical screw conveyor unit 100 can be permanently connected to the cylindrical shaft body, for example by means of welding techniques, for example by means of a weld seam 232. Alternatively, the support area 210 can be integrally formed with the cylindrical shaft body of the shaft 230.

[0059] The helical screw conveyor unit 100 is arranged such that the helical member 30 extends the course of the shaft body helix 240 of the cylindrical shaft body to form therewith a common shaft body helix unit.

[0060] The base body 10 of the helical screw conveyor unit 100 is concavely curved. In that case, the base body can be configured in such a way that in the use position of the worm shaft 200, the support area 210 is completely enveloped by the base body 10 of the helical screw conveyor unit 100 arranged on the support area 210 (not shown). For example, two helical screw conveyor units 100 each configured as half shells can completely envelope the shaft body part 210.

[0061] Alternatively, the base body 10 can be a foot member 32 of the helical member 30, which is arranged in a radially inner region of the helical member 30 and can be replaceably arranged in a fixing region 40 configured as a groove in the support region 210.

[0062] 1-7, the helical frequency of the helical member 30 is the same as the helical frequency of the shaft body helix 240. However, the helical frequency or pitch of the helical member 30 can be increased compared to the helical frequency of the shaft body helix 240.

[0063] In order to rotatably support the worm shaft 200 in the worm extruder 300, the worm extruder has at least one rotation bearing 250. In order to eliminate the radial and axial force load of the gear mechanism of the worm extruder 300, the worm shaft 200 can be double-bearing, which allows the worm extruder 300 to have a longer life.

[0064] The preferred material for a helical screw conveyor unit 100 of the type described above and a worm shaft 200 of the type described above is steel. [Explanation of symbols]

[0065] 10 Base body, in particular the foot member of the helical member 30 12 a first end region of the base body, in particular a first end region extending perpendicular to the longitudinal axis of the base body 14 a second end region of the base body, in particular a second end region extending perpendicular to the longitudinal axis of the base body 16 Upper side, especially outer side, of the outer surface of the base body 10 18 Inside of the outer surface of the base body 10 20 Radial or concave opening in base body 10 30 Spiral member of the spiral screw conveyor unit 100 34 Fixing member for the helical member 30 40: fixing area of ​​the base body 10, in particular a fixing area formed in a u-shape, a square member or a receiving member 42 Filling body 100 Spiral Screw Conveyor Unit 200 worm shaft or conveyor worm or extruder worm, in particular a bar-shaped worm shaft having a screw-shaped or helically wound helical member 240, 30 210 shaft body member or support area of ​​the worm shaft shaft 230, in particular the shaft rest area or support area of ​​the shaft 230 of the worm shaft 200, configured to support the base body 10 of the helical screw conveyor unit 100 212 Fastening means for the shaft body member 210, in particular a screw 230 has a support area 210 configured to support the shaft or bar-shaped base body of the worm shaft 200, in particular the cylindrical shaft body, and the base body 10 of the helical screw conveyor unit 100 232 A welded joint, particularly a fillet joint, for connecting the cylindrical shaft body 230 to the base body 10 240 A shaft body spiral or a spiral member wound in a spiral, helix or screw shape on the worm shaft 200 250 Rotary Bearing (see Figure 4) 300 Warm Extruder 340 Screen Drum 350 Press cake outlet 360 Digestive fluid inlet 370 Resistance, especially the counter pressure cone L Longitudinal axis

Claims

1. A helical screw conveyor unit (100) configured as a replacement member for a screw- or helically wound helix (240) of a worm shaft (200), the helical screw conveyor unit (100) having a base body (10) extending along a longitudinal axis (L), the base body (10) having two axial end regions (12, 14) and a mantle surface connecting the end regions (12, 14) with each other, on an upper side (16) of the mantle surface at least one screw-wound helical member (30) is arranged, the screw-wound helical member (30) extending radially outwardly away from the upper side (16), the upper side (16) of the jacket surface is curved concavely in the shape of a shell about the longitudinal axis (L) and the base body (10) has radial openings (20) which are configured such that a fastening area (40) of a shaft (230) of the worm axle (200) can be guided through said opening (20) in a direction perpendicular to the longitudinal axis (L) and can be positioned in a hollow space formed by the base body (10), - said helical member (30) has at most half a helical turn, - the outer surface of the base body (10) has an inner surface (18) adapted to rest on the fixing area (40); - a spiral screw conveyor unit, characterized in that the spiral screw conveyor unit (100) has at least one fastening member (34) configured for releasably fastening the base body (10) to the fastening area (40).

2. 2. The helical screw conveyor unit according to claim 1, characterized in that the base body (10) extends in a semicircular or half-shell shape around the longitudinal axis (L), in particular is configured as a half-shell, and the helical element (30) has half a helical revolution.

3. 3. The helical screw conveyor unit according to claim 1 or 2, characterized in that the inner side (18) of the base body (10) is shaped in such a way that, as a result of the inner side (18) of the base body (10) resting on the fixing area (40) of the worm shaft (200), an orientation of the helical member (30) of the helical screw conveyor unit (100) on the worm shaft (200) is determined and a radial mobility of the base body (10) on the worm shaft (200) is at least limited.

4. 4. The helical screw conveyor unit according to claim 3, characterized in that for the orientation of the helical member (30) on the worm shaft (200), the inner side (18) of the outer mantle surface has a contour of a shape complementary to the fixing area (40) of the shaft (230).

5. 4. The helical screw conveyor unit according to claim 2 or 3, characterized in that the helical element (30) is shaped in such a way that, as a result of the placement of the inner side (18) of the base body (10) on the fixing area (40) of the worm shaft (200), the helical element (30) is oriented at least substantially in the extension of the course of the helix (240) wound in a screw or helical shape of the worm shaft (200).

6. A worm shaft (200) for use in a worm extruder (300), comprising a shaft (230) extending along a longitudinal axis (L) and provided with a helix (240) wound in a screw-like or helical configuration, 6. A worm shaft comprising at least one helical screw conveyor unit (100) according to at least one of claims 1 to 5 and at least one fastening means (212) adapted for releasably fastening to said fastening member (34).

7. 7. The worm shaft according to claim 6, characterized in that the fastening means (212) is configured to cooperate with the fastening member (34) of the helical screw conveyor unit (100) such that the helical screw conveyor unit (100) is releasably fastenable to the fastening area (40) of the worm shaft (200).

8. 8. A worm shaft (200) according to claim 6 or 7, characterized in that the fastening area (40) of the worm shaft (200) is shaped as follows, i.e. in such a way that the radial movement of the base body (10) resting on the fastening area (40) is at least limited.

9. 9. A worm shaft (200) according to at least one of claims 6 to 8, characterized in that it has at least two fastening regions (40), which are formed by at least one recess or at least one groove in the otherwise cylindrical shaft body member (210) and which are arranged radially and axially offset with respect to one another.

10. 10. The worm shaft (200) according to at least one of claims 6 to 9, characterized in that the shaft (230) has a cylindrical shaft body and the fastening area (40), the fastening area (40) being associated with a support area (210) of the shaft (230) configured to support the base body (10) of the helical screw conveyor unit (100) and having a smaller cross-sectional diameter than the cylindrical shaft body.

11. 11. The worm shaft (200) according to claim 10, characterized in that the support region (210) is arranged eccentrically, in particular in a region near an end of the shaft (230), for example in the region of the end.

12. 12. A worm shaft according to claim 10 or 11, characterized in that the support area (210) has at least two helical screw conveyor units (100) according to at least one of claims 1 to 5, the helical screw conveyor units (100) being arranged as follows: the helical member (30) of the helical screw conveyor unit (100) extends the course of the helix (240) of the cylindrical shaft body and forms together therewith a common shaft body helical unit.

13. 13. The worm shaft according to at least one of claims 10 to 12, characterized in that the worm shaft has at least two helical screw conveyor units (100), each arranged adjacent to one another and together forming one complete helical revolution completely around the shaft (230).

14. A worm extruder (300) for dewatering suspensions, in particular digestive juices obtained by anaerobic fermentation of organic material, comprising an extruder chamber and a worm shaft (200) having a helical member wound in a screw shape therein, the worm shaft (200) being mounted (250) rotatably about its longitudinal axis (L), 13. A worm extruder comprising: a worm shaft (200) according to claim 6; a shaft (230) of the worm shaft (200) having at least two helical screw conveyor units (100), in particular surrounded by at least two helical screw conveyor units (100); and the helical screw conveyor units (100) according to claim 1;

15. A method of providing a worm shaft (200) configured for use in a worm extruder (300), comprising: - a helical screw conveyor unit (100) according to at least one of claims 1 to 5 is arranged in said fixing area (40), and - said helical screw conveyor unit (100) is removably fixed to said fixing area (40) by means of said fixing member (34) associated with said helical screw conveyor unit.

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