Screw conveyor unit, worm, worm extruder and worm providing method

Abstract

In order to develop a screw conveyor unit (100) that can be maintained with little effort, the screw conveyor unit is designed as a replaceable component for a helical or spirally wound screw (240) of a worm (200) of a screw extruder and has a body (10) with a spirally wound screw element (30), according to the invention: the top side (16) of the side surface is shell-shaped and concavely curved around the longitudinal axis (L), and the body (10) has a radial opening (20) designed to allow the fastening area (40) of the shank (230) of the worm (200) to pass through; the screw element (30) has a maximum of half a spiral turn; the side surface of the body (10) has an inner surface (18) designed to rest on the fastening area (40); and the screw conveyor unit (100) has at least one fastening element (34) designed to releasably fasten the body (10) to the fastening area (40).

Description

Technical Field

[0001] The present invention relates to a screw conveyor unit.

[0002] The invention also relates to a worm, in other words a conveyor worm.

[0003] The invention also relates to a worm extruder.

[0004] The invention finally relates to a method for providing a worm. Background Art

[0005] For example, the documents EP 1 072 574 A2, US 2017 / 08778 A1 and EP 2 792 739 A1 describe screws used in screw extruders and the general construction of screw extruders for dewatering suspensions.

[0006] Document EP1072574A2 discloses a fermentation device having a fermenter and a dehydration device in the form of a cylindrical worm conveyor. The worm conveyor extends along a linear axis. Figures 1 to 3 As shown, the screw and the worm together form a fixed unit.

[0007] Document US2017 / 08778A1 discloses a worm extruder for dewatering aqueous suspensions of organic matter. The machine comprises an extruder chamber in which an extruder worm with a screw element spirals and is mounted for rotation about its longitudinal axis. To facilitate easy and rapid maintenance of the worm extruder, US2017 / 08778A1 discloses a multi-piece screen basket that pivots upward, allowing easy access to the extruder chamber and enabling single-person screen replacement.

[0008] Document EP 2 792 739 A1 discloses a double screw in an extruder chamber as is known for cell-disrupting extruders. The screw conveyor unit has so-called cleaning teeth on the adjacent screws.

[0009] Anaerobic digestion (AD) is a biological process that recovers energy from residual organic matter, particularly green waste, by converting it into biogas. The substrate is digested under anaerobic conditions in a fermenter. Here, the fermentable material contained in the waste is mixed with a liquid, and the resulting fermentable material suspension is anaerobically fermented in the fermenter.

[0010] The digestate formed during the fermentation of the fermentation material suspension is dewatered by means of a screw press, wherein the water is separated as it is pressed, resulting in a press cake having a higher dry matter content relative to the digestate. After leaving the fermenter, the substrate is separated into solid and liquid digestate residues by means of a screw press.

[0011] A worm extruder essentially consists of an inner worm with a spirally wound screw and a screen drum or sieve cylinder surrounding the worm. Digestate for dewatering is pumped into the sieve drum via a digestate inlet. The worm rotates, thereby conveying the digestate toward the press cake outlet. There, there is a resistance, such as a counterpressure cone, against which the digestate is pressed. The pressurized water is discharged through the press water outlet.

[0012] The further the digestate is conveyed, that is, in the direction of resistance, the greater the reduction in volume and the higher the pressure acting on the digestate. Consequently, even more liquid is squeezed out of the digestate and discharged as pressurized water. The dehydrated press cake leaves the worm extruder through the press cake outlet.

[0013] During operation, the screws of a worm extruder wear over time. The greater the pressure exerted by the screw on the digestate, the faster this wear occurs, and it is particularly noticeable in the front area of the worm, near the cake outlet. Wear causes the pressure point to shift rearward, thereby reducing the digestate dewatering efficiency. Worn screws must be repaired or replaced.

[0014] As in US2017 / 08778A1 Figure 2 and Figure 3 As shown, the screw is usually fixedly connected, such as welded, to the shank of the worm. Therefore, when individual screws are worn, a large amount of welding work is required or the entire worm must be replaced.

[0015] EP 0 098 340 A1 discloses a worm pump for conveying solid and granular materials. To replace the end of a helical worm, which is subject to particularly high wear, a replaceable sleeve is provided in the end that can be axially removed from the worm. The worm must be removed from the worm pump to replace the sleeve.

[0016] Furthermore, document GB859416A discloses a worm screw conveyor with a replaceable screw element that can be assembled in the form of a sleeve. To allow the individual parts of the worm to be disassembled for maintenance and repair work, the worm is constructed from a plurality of sleeve-like longitudinal sections assembled together. These longitudinal sections are removably secured to the worm shank by semicircular shell-like bearings. After the bearings are loosened, the sleeve-like longitudinal sections can be removed axially from the worm shank. To do this, the worm must be disassembled from its bearing on at least one side.

[0017] In order to eliminate the need for the tedious welding work of disassembling and repairing blades after the blades of the worm conveyor are worn, document CN212831025U discloses that blades are fastened to the shaft by grooves and screws. Each blade is a separate paddle piece that is screwed onto the shaft independently of each other. Summary of the Invention

[0018] The present invention is based on the object of improving a screw conveyor unit of the type mentioned at the outset, a worm of the type mentioned at the outset, a worm extruder of the type mentioned at the outset, and a method of the type mentioned at the outset so that the screw conveyor unit can be repaired with minimal maintenance effort. In particular, it is desired that a screw conveyor unit designed as a replaceable screw element be replaceable without having to remove the worm from its bearing. Furthermore, the aim is to reduce the maintenance costs of the worm.

[0019] The object is achieved by a screw conveyor unit, a worm, a worm extruder and the method.

[0020] The present invention is based on the fact that a screw conveyor unit can be replaceably mounted radially on the fastening region of the worm shank. The screw conveyor unit can thus be mounted as a replaceable spare part on a rotatably mounted worm of a worm extruder. The present invention thus allows the screw conveyor unit to be quickly replaced, since the body of the screw conveyor unit has a radial opening designed to accommodate the shank. The screw conveyor unit can thus be replaceably mounted on the shank, and the screw conveyor unit can be replaced even when the shank is mounted at its axial end in at least one rotary bearing.

[0021] In the present case, "radial" refers to a direction perpendicular to the longitudinal axis (L) of the worm shank or worm body. Radial replaceability therefore allows efficient replacement of the screw without removing the screw shaft from its bearings and a long operating cycle of the worm.

[0022] The worm shank is a rod-shaped element for transmitting rotational motion. The screw conveyor unit can be mounted as a removable spare part on the fastening area of the shank. The screw conveyor unit is therefore advantageously designed to be removably mounted on the fastening area of the worm as described above. Furthermore, the worm is advantageously suitable for installation in a worm extruder of the type described above.

[0023] In order to detachably fasten the screw body to the fastening region, the screw conveyor unit has at least one fastening element.Thus, the fastening element of a screw conveyor unit of the above-mentioned type is advantageously detachably connected to a fastening mechanism, in particular a fastening structure, of a worm of the above-mentioned type.

[0024] In an advantageous embodiment, the main body is a foot of the spiral element, the foot being arranged at a radially inner region of the spiral element. Here, the fastener is configured to removably fasten the foot to the fastening region. Here, the foot is in the form of a foot that can be mounted in the fastening region, and the spiral element extends outwardly away from the foot.

[0025] In order to easily fasten the screw element radially detachably to the worm, the fastening element can, in its use position, extend radially into a support region of the shank, which is designed to support the conveyor screw unit and to fasten a foot element located thereon to the support region.

[0026] In one advantageous embodiment, the support region of the handle has at least two screws, each of which is assigned at least one fastener, and the fasteners of adjacent screws are arranged axially and radially offset relative to one another. The fasteners are preferably hexagon socket screws, and the fastening means are preferably threads. Alternatively, the fasteners may interact with the fastening means in a removable snap-on manner.

[0027] The inner surface of the body of the screw conveyor unit of the above type is preferably configured to rest, in particular be mounted on the fastening area of the worm of the above type. In other words, the fastening area is assigned to the area of the worm that is configured to support the body of the screw conveyor unit.

[0028] In order to make the replacement of the screw conveyor unit on the worm particularly simple, the main body inner surface is advantageously shaped so that the orientation of the screw of the screw conveyor unit on the worm is limited due to the main body inner surface being placed on the worm fastening area, and the radial mobility of the main body on the worm is at least limited. The main body inner surface and the fastening area therefore advantageously have a shape or structure that interacts and prevents the screw conveyor unit from slipping or rotating around the radial direction of the shank. Here, the radial rotational movement of the screw conveyor unit around the shank has been prevented by the interaction of the shape or structure of the fastening area with the shape or structure of the main body inner surface. The fastening mechanism is then used for further or additional fixing. As described in more detail below, this fastening achieved by shape or structure can, for example, be achieved by the square shape of the fastening area. The fastening area is configured as a fastener for removably fastening the screw conveyor unit and is assigned to a supporting area of the worm shank, which is configured to support the screw conveyor unit. The fastening area has at least one fastening mechanism such as a fastening structure. The supporting region advantageously has at least two fastening regions, so that at least two screw conveyor units of the above-described type can advantageously be detachably fastened to the supporting region of the worm.

[0029] The worm therefore advantageously has at least two screw conveyor units. Here, the fastening regions of the support region are preferably configured so that adjacent screw conveyor units are each arranged axially and radially offset relative to one another, for example, offset in a mirror-symmetrical manner. In this advantageous embodiment, the worm has at least two screw elements, which are arranged axially and radially offset relative to one another. Therefore, the support region has at least two fastening regions, which are arranged axially and radially offset relative to one another. It is also advantageous in this embodiment if the fastening elements of adjacent screw conveyor units are arranged axially and radially offset relative to one another, for example, arranged to be staggered by 90 degrees, for example, perpendicular to one another.

[0030] The spiral element has partial turns, for example, a quarter to a half of a turn. A plurality of adjacent coil elements together form a spiral, helical, or helical turn. The plurality of spiral turns together form the helix, helical, or spirally wound spiral of the worm. Because the spiral element is replaceable in the present invention, increased material wear of the spiral element can be tolerated compared to worms known from the prior art with non-detachable spiral elements, and the resistance of the worm extruder can be increased, for example by enlarging or lengthening the back pressure cone to provide greater force for dehydrating the digestate.

[0031] The main body of the screw conveyor unit has a radial opening. The fastening region can be passed through the opening in a radial direction, i.e., perpendicular to the longitudinal axis (L) of the main body, and arranged on the inner surface of the main body. In other words, the support region can be guided through the opening and accommodated in the cavity surrounded by the concave main body.

[0032] The fastener is preferably configured to provide a form-fit connection between the main body and the support area of the handle or the shaft, such as a screw such as a hexagon socket screw. Alternatively, the fastener can be configured to provide a snap connection or a clamping connection.

[0033] In order to be able to arrange the body so that it rests on the support area, the body inner surface has a complementary shape to the fastening area and the outer side of the body is concavely curved and preferably extends in the shape of a half shell or semicircle around the longitudinal axis.

[0034] The fastening region has at least one support surface configured to support the main body, in particular its inner surface. To prevent the main body from slipping on the support surface, the inner surface of the side surface of the main body advantageously has at least one profile configured for securing the main body on the fastening region and advantageously having a complementary shape to the fastening region or to its support surface. The profile of the inner surface of the main body of the screw conveyor unit preferably has a U-shaped or n-shaped cross-section.

[0035] The conveyor screw can be replaced particularly quickly and easily on the worm if the screw is shaped such that, due to the inner surface of the body resting on the fastening region of the worm, it is oriented at least substantially to continue the course of the helix or spiral wound helix of the worm.

[0036] In order to prevent the main body from radially slipping on the handle, the inner surface of the side surface can be, for example, a right-angled shape, or can be curved, arched or stepped. For example, the cross section of the fastening area can be U-shaped, and the cross section of the inner surface of the main body can also be N-shaped, or vice versa.

[0037] The support area of the handle can be square, at least in the region of the fastening area. Alternatively, the fastening area can be formed by at least one concave surface or at least one groove of the otherwise cylindrical support area. For example, the fastening area can be a U-shaped or N-shaped concave surface of the otherwise cylindrical support area. To prevent the screw conveyor unit from slipping on the fastening area, the fastening area advantageously has a square seat.

[0038] The spiral element comprises a portion or a part of a spiral turn, preferably half of a spiral turn. Alternatively, the spiral element may comprise, for example, one-third of a spiral turn or one-quarter of a spiral turn. The screw conveyor unit comprises at least one spiral element, preferably a plurality of spiral elements, such as four, arranged adjacent to each other. To achieve a precisely fitting connection, the spiral elements of the adjacent screw conveyor units may be welded to each other and ground together.

[0039] Advantageously, the fastener, in its position of use, extends radially through the support area and into the main body or through the main body of at least one screw conveyor unit arranged on the support area. The fastener is particularly preferably positioned so that its end extending from the support area protrudes into the main body of the screw conveyor unit. Thus, to replace the screw conveyor unit, the fastener only needs to be partially loosened, for example, only from the main body of the screw conveyor unit, while remaining fastened to the support area. This prevents the fastener from being lost.

[0040] The screw shaft advantageously has at least one screw conveyor unit of the above-described type, which is detachably fastened to the fastening region.

[0041] In addition to the screw conveyor unit, the handle can also include a cylindrical shank extending along the longitudinal axis and having at least one helical coil wound thereon. The fastening region of the support region, which also extends along the longitudinal axis, has a smaller cross-sectional diameter than the cross-sectional diameter of the cylindrical shank. This allows the screw conveyor unit to be positioned on the support region so that the top side of the lateral surface of the screw conveyor unit ends flush with the cylindrical body.

[0042] The support area is preferably arranged eccentrically, in particular in the proximal region of the cylindrical shaft, such as the end region. The worm can thus be arranged in the worm extruder such that at least one replaceable screw is located in the front region of the worm extruder, near the filter cake outlet. Replacing only the front screw, which is most susceptible to wear, allows for easy, quick, and cost-effective servicing of the worm.

[0043] In an advantageous embodiment of the method according to the invention, the worm is repaired as follows:

[0044] at least one fastening means fastening the first screw conveyor unit to the fastening region is released,

[0045] - the first screw conveyor unit is removed from the worm screw,

[0046] - placing another screw conveyor unit on the fastening area, and

[0047] is detachably fastened to the fastening region by means of a fastening mechanism assigned to the further screw conveyor unit.

[0048] Finally, the invention relates to the use of at least one screw of the aforementioned type in a screw press of the aforementioned type for separating solid and liquid digestion residues from residual biomass, in particular green waste, processed by a fermenter. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] As mentioned above, there are various possibilities for advantageous embodiments and improvements of the teachings of the present invention. In this regard, firstly, reference is made to the requirements of the corresponding aspects and secondly, in the following Figure 1-7 Further embodiments, features and advantages of the present invention will be discussed in more detail based on the illustrated embodiments.

[0050] Figure 1 A perspective view of a longitudinal section through a first embodiment of a worm according to the invention, with a detachably mounted screw conveyor unit according to the invention, which can be replaced according to the method according to the invention;

[0051] Figure 2 Shown in longitudinal section Figure 1 worm;

[0052] Figure 3 Show Figure 1 Side view of the worm;

[0053] Figure 4 Show Figure 2 Detailed view of the front area of the worm;

[0054] Figure 5 Show Figure 1 The screw conveyor unit along Figure 3 The cross section of line BB is shown;

[0055] Figure 6 Shown in exploded view Figure 1 worm;

[0056] Figure 7 The invention shows Figure 1 An embodiment of a worm extruder in which the worm is in the form of a screw.

[0057] exist Figures 1 to 7 In the present disclosure, the same or similar embodiments, components or features are indicated by the same reference numerals. DETAILED DESCRIPTION

[0058] Figure 1 An embodiment of a screw conveyor unit 100 for a worm 200 is shown. The screw conveyor unit 100 has a main body 10 extending along a longitudinal axis L. The main body has two end regions extending perpendicularly to the longitudinal axis, in other words, they are opposite each other in the direction of the longitudinal axis. The end regions 12, 14 are connected by a side surface, and at least one helically wound screw 30 is arranged around the top side or outer surface of this side surface.

[0059] exist Figures 1 to 3 In the embodiment shown, the worm 200 has a plurality of, for example two, spiral elements 30. In order to connect the spiral elements 30 with an exact fit, these can be welded to one another and ground together.

[0060] The at least one spiral element 30 has a partial spiral turn, in particular a quarter to a half of a spiral turn. The body is concavely curved, i.e., inwardly domed, and has a radial opening 20. In other words, the body is hollow and extends in a curved manner about the longitudinal axis L. The body preferably extends about the longitudinal axis L in the shape of a sector, such as a half-shell.

[0061] The screw conveyor unit 100 is designed to be replaceably mounted in a screw 200, preferably in a screw 200 of a screw extruder 300 designed for dewatering digestate obtained by anaerobic digestion of organic matter.

[0062] Figure 6An exploded view of the worm 200 is shown. The worm has four screw conveyor units 100, which together form two complete spirals. The adjacent screw conveyor units 100 are arranged to be radially offset by 180 degrees relative to each other, i.e., they are arranged in a mirror-symmetrical manner. In order to removably fasten the main body 100 to the fastening area 40 of the support area 210, the screw conveyor units each have two hexagon socket screws 34. The fastening area 40 is formed in the form of a partial square or in the form of a rectangle. Those areas of the support area 210 that are opposite the screw conveyor unit 100 or opposite the fastening area 40 are designed as filler bodies. These protect and stabilize the support area 210. The filler bodies can be fixedly connected to the support area 210, for example, formed integrally with the support area 210, or removably fastened to the support area 210. The filler bodies are concavely curved around the longitudinal axis L.

[0063] like Figure 7 As shown, a worm extruder 300 has an inner worm 200 with helically wound screws 30, 210 extending outwardly therefrom, and a screen drum 340 surrounding the worm 200. The screen drum 340 may have a pivotable screen cover, allowing easy access to the worm and quick replacement of screens and wear parts.

[0064] In order to be replaceably mounted in the worm 200 , the screw conveyor unit 100 has:

[0065] - an inner surface 18 on the side of the body 10 , which is designed to accommodate the support area 210 of the handle 230 ,

[0066] At least one fastener 34 designed for releasable fastening of the inner surface 18 of the support region 210 .

[0067] The screw conveyor unit 100 is therefore a detachably fastened or replaceable component for the worm 200 .

[0068] In an embodiment of the invention not shown here, the worm 200 can have only a replaceable screw 30. Alternatively, Figures 1 to 7 As shown, only a partial region of the worm 200 , for example the front region located in the vicinity of the press cake outlet 350 in the operating position, is designed as a replaceable conveyor screw unit 100 .

[0069] Figures 1 to 7 The worm screw shown has not only a replaceable screw conveyor unit 100, but also a shank 230 with a cylindrical shank and a shank spiral 240 spirally wound around the shank 230. In the area of the cylindrical shank, the shank spiral 240 is non-detachably connected to the shank 230, for example formed integrally therewith or welded thereto.

[0070] The support region 210 of the screw conveyor unit 100 can be non-detachably connected, for example using welding techniques, for example via a root seam 232 to the cylindrical shaft. Alternatively, the support region 210 can also be formed integrally with the cylindrical shaft of the handle 230.

[0071] The screw conveyor unit 100 is arranged in such a way that the screw 30 continues the course of the shaft screw 240 of the cylindrical shaft and thus forms a common shaft screw unit.

[0072] The main body 10 of the screw conveyor unit 100 is concavely curved. The main body can be designed so that, in the operating position of the worm 200, the support region 210 is completely surrounded by the main body of the screw conveyor unit 100 arranged on the support region 210 (not shown). For example, two screw conveyor units 100 designed as half shells can each completely surround the shaft element 210.

[0073] Alternatively, the body 10 may be a foot piece 32 of the screw 30 , which is arranged at a radially inner region of the screw 30 and can be replaceably mounted in the fastening region 40 of the support region 210 , which is designed as a groove.

[0074] exist Figures 1 to 7 In the embodiment shown, the spiral frequency of the screw 30 is the same as the spiral frequency of the shaft spiral 240. However, it is also possible that the spiral frequency or pitch of the screw 30 is increased relative to the spiral frequency of the shaft spiral 240.

[0075] To rotatably mount the worm 200 in the worm extruder 300 , it has at least one rotary bearing 250 . To free the transmission of the worm extruder 300 from radial and axial forces, the worm 200 can have a double bearing arrangement. This ensures a longer service life for the worm extruder 300 .

[0076] A preferred material for a screw conveyor unit 100 of the type described above and a worm 200 of the type described above is steel.

[0077] Reference Signs List

[0078] 10 The main body of the screw 30, especially the foot

[0079] 12 A first end region of the main body, in particular a first end region of the main body extending perpendicularly to the longitudinal axis

[0080] 14 A second end region of the main body, in particular a second end region of the main body extending perpendicularly to the longitudinal axis

[0081] 16 The top side of the side of the main body 10, especially the outer side

[0082] 18 The inner side of the side of the main body 10

[0083] 20 radial opening or concave opening of the main body 10

[0084] 30 screw conveyor units 100 screw elements

[0085] 34 screw member 30 fastener

[0086] 40 The fastening area of the main body 10, in particular the U-shaped fastening area, the square groove or the receiving groove

[0087] 42 filler body

[0088] 100 screw conveyor units

[0089] 200 Worm or conveyor worm or extruder worm, in particular a rod-shaped worm shank with a helical or spirally wound screw 240, 30

[0090] 210 The worm shaft 230 is designed to support the shaft part or support area of the main body 10 of the screw conveyor unit 100, in particular, the shaft receiving area or support area of the shaft 230 of the worm 200.

[0091] 212 The fastening mechanism of the rod body 210, in particular the thread

[0092] 230 shank or rod-shaped body of the worm 200 , in particular with a cylindrical shaft and a support region 210 designed to support the body 10 of the screw conveyor unit 100

[0093] 232 is used to connect the cylindrical rod 230 to the main body 10, especially the root seam

[0094] 240 worm 200 spiral or spiral or spirally wound rod body spiral or spiral member

[0095] 250 rotating bearing (see Figure 4 )

[0096] 300 Worm Extruder

[0097] 340 Screen Drum

[0098] 350 Pressed cake export

[0099] 360 Digestive Inlet

[0100] 370 resistance, especially the back pressure cone

[0101] L longitudinal axis

Claims

1. A screw conveyor unit (100) designed as a replaceable component for a spirally or helically wound screw (240) of a worm (200), the screw conveyor unit (100) having a body (10) extending along a longitudinal axis (L), wherein: The body (10) has two axial end regions (12, 14) and a side surface connecting the end regions (12, 14) to one another, wherein at least one spirally wound helical element (30) is arranged on a top side (16) of the side surface and extends radially outwards away from the top side (16), characterized in that - the top side (16) of the side surface is concavely curved around the longitudinal axis (L) in a shell-like manner, and the body (10) has a radial opening (20), wherein the radial opening (20) is designed so that the fastening region (40) of the shank (230) of the worm (200) can pass through the radial opening (20) in a direction perpendicular to the longitudinal axis (L) and can be arranged in the cavity formed by the body (10), - the spiral (30) has at most half a spiral turn, - the side surface of the body (10) has an inner surface (18) designed to rest on the fastening area (40), - the screw conveyor unit (100) has at least one fastener (34) designed to detachably fasten the body (10) to the fastening area (40), and - the inner surface (18) of the body (10) is shaped such that, due to the seating of the inner surface (18) of the body (10) on the fastening region (40) of the worm (200), the orientation of the screw (30) of the screw conveyor unit (100) on the worm (200) is defined and the radial mobility of the body (10) on the worm (200) is at least limited, wherein the inner surface of the body and the fastening region have shapes that interact and prevent rotational movement of the screw conveyor unit about the handle.

2. The screw conveyor unit according to claim 1, characterized in that The body (10) extends in the shape of a semicircle or a half shell around the longitudinal axis (L), and the spiral (30) has half of a spiral turn.

3. The screw conveyor unit according to claim 1, characterized in that For the orientation of the screw (30) on the worm (200), the inner surface (18) of the side surface has a contour that is complementary in shape to the fastening region (40) of the shank (230).

4. The screw conveyor unit according to claim 1 or 2, characterized in that The spiral (30) is shaped so that, due to the inner surface (18) of the body (10) resting on the fastening region (40) of the worm (200), the spiral (30) is at least substantially oriented to continue the course of the spiral (240) of the worm (200) which is wound in a helical or spiral manner.

5. The screw conveyor unit according to claim 2, characterized in that The main body (10) is designed in a half-shell shape.

6. A worm (200) for use in a worm extruder (300), the worm (200) having a shank (230) extending along a longitudinal axis (L) and having a spiral (240) wound in a helical or spiral manner, characterized in that At least one screw conveyor unit (100) as claimed in at least one of claims 1 to 5 and at least one fastening mechanism (212) are provided, the at least one fastening mechanism (212) being designed to fasten the fastening element (34) in a detachable manner.

7. The worm according to claim 6, characterized in that The fastening mechanism (212) is designed to interact with the fastening element (34) of the screw conveyor unit (100) so that the screw conveyor unit (100) can be detachably fastened to the fastening region (40) of the worm (200).

8. The worm (200) according to claim 6 or 7, characterized in that The fastening region (40) of the worm (200) is shaped such that radial movement of the body (10) placed on the fastening region (40) is at least limited.

9. The worm (200) according to claim 6, characterized in that At least two fastening regions (40) are provided, which are formed by at least one recess or at least one groove of the otherwise cylindrical shaft part and are arranged radially and axially offset relative to each other.

10. The worm (200) according to claim 6, characterized in that The handle (230) has a cylindrical shank and the fastening region (40), wherein the fastening region (40) is assigned to a support region (210) of the handle (230) designed to support the body (10) of the screw conveyor unit (100) and has a smaller cross-sectional diameter than the cylindrical shank.

11. The worm (200) according to claim 10, characterized in that The support area (210) is arranged eccentrically.

12. The worm according to claim 10 or 11, characterized in that The support area (210) has at least two screw conveyor units (100) designed as described in at least one of claims 1 to 5, wherein the screw conveyor unit (100) is arranged so that the screw element (30) of the screw conveyor unit (100) continues the direction of the rod spiral (240) of the cylindrical rod body and forms a common rod spiral unit therewith.

13. The worm according to claim 10, characterized in that The worm has at least two screw conveyor units (100), which are respectively arranged adjacent to one another and together form a complete spiral turn that completely surrounds the shank (230) once.

14. The worm (200) according to claim 11, characterized in that The support region (210) is eccentrically arranged in the proximal region of the handle (230).

15. The worm (200) according to claim 11, characterized in that The support region (210) is arranged eccentrically on an end region of the handle (230).

16. A worm extruder (300) for dewatering suspensions, comprising an extruder chamber, wherein a worm (200) having a spirally wound screw is mounted (250) in the extruder chamber so as to be rotatable about its longitudinal axis (L), and wherein: The worm (200) is designed as claimed in any one of claims 6 to 15, the shank (230) of the worm (200) has at least two screw conveyor units (100), and the screw conveyor units (100) are designed as claimed in any one of claims 1 to 5.

17. The worm extruder (300) according to claim 16, characterized in that The worm extruder (300) is used to dehydrate the digestate obtained by anaerobic digestion of organic matter.

18. The worm extruder (300) according to claim 16, characterized in that The shank (230) of the worm (200) is surrounded by at least two screw conveyor units (100).

19. A method (200) for providing a worm designed for use in a worm extruder (300), characterized in that - a screw conveyor unit (100) designed as claimed in any one of claims 1 to 5 is arranged on the fastening area (40), and - is detachably fastened to the fastening region (40) by means of a fastening element (34) assigned to the screw conveyor unit (100).

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