Fluted disc cleaner

Abstract

The invention relates to a fluted disc cleaner for pre-cleaning pre-comminuted plastic waste, in particular plastic chips, in a plastic recovery process, comprising two mutually facing cleaning tools, at least one of which is driven in rotation by means of a rotary drive, each of which has a working surface with cleaning teeth, wherein an annular working gap is defined between the opposite working surfaces for pre-cleaning plastic waste, and wherein the cleaning teeth of the opposite working surfaces mesh with each other at a distance from each other, and wherein the fluted disc cleaner further comprises an inlet opening into the working gap at the center, the invention relates to a fluted disc cleaner having an inlet, which has an input means for inputting plastic waste to be cleaned, and having an outlet, which is arranged on the outer edge of the working gap and through which plastic waste pre-cleaned in the working gap is discharged, the width of the working gap narrows outwards in the radial direction from the inlet in a first section, and the width of the working gap is constant in a second section arranged radially outside the first section.

Description

Technical Field

[0001] The present invention relates to a toothed disc cleaner for pre-cleaning pre-crushed plastic waste, in particular plastic fragments, in a plastic recycling process, comprising two cleaning tools facing each other, at least one of which is rotationally driven by means of a rotary drive, wherein the cleaning tools respectively have working surfaces provided with cleaning teeth, wherein an annular working gap is defined between the working surfaces opposite to each other for pre-cleaning the plastic waste, and wherein the cleaning teeth of the opposing working surfaces mesh with each other at intervals, the toothed disc cleaner also comprising an inlet leading centrally into the working gap, the inlet having an input device for inputting the plastic waste to be cleaned, and the toothed disc cleaner comprising an outlet arranged on the outer edge of the working gap, through which the plastic waste pre-cleaned in the working gap is discharged. Background Art

[0002] Plastic waste, such as PET beverage bottles, blister packages made of PET (deep-drawn PET film), plastic waste made of polyolefins, etc., must be cleaned during the recycling process. Very high quality requirements should be met here. The allowed dirt is in the ppm range. The toothed disc cleaner involved here is used to pre-clean such plastic waste. The main cleaning can be carried out subsequently. For pre-cleaning, the plastic waste is first pre-crushed, especially pre-crushed into plastic fragments or plastic fragments. The crushing can be carried out, for example, in a crusher (rotor and screen basket with knives and corresponding knives). The desired fragment size is produced by the hole diameter in the screen basket. The separation of metals from plastic waste is usually carried out in pre-sorting by means of magnetic separation and eddy current separation. It is also often sorted according to color and / or plastic type before crushing plastic waste.

[0003] On the surface of plastic waste (including production waste) there are a variety of external contaminants, such as adhesive labels made of paper, plastic film or metal foil, printed color layers with printed seals if necessary, metallization of the surface, adhesions of clay, sand, fat, oil and various food residues. The key to recycling into high-quality polymers (corresponding to primary plastics) is to remove firmly adhering (external) coatings almost without residue, whether with printing inks, with metallized surfaces or with adhesion promoters (adhesives).

[0004] For example, conventional washing techniques with cold or hot process water are used for the cleaning. However, in this case, for example, hot melt adhesives, printing inks and metallization are not completely peeled off. Complete peeling is understood to be a residual contamination of less than 10 ppm, which only slightly produces so-called VOCs (volatile organic components) during further thermal treatment, such as extrusion or melting. For example, for conventional caustic soda hot washing, printing inks can only be peeled off when surfactants specifically suitable for caustic soda are used and the fragments penetrate for a long time during the cleaning. The peeling of hot melt adhesives is also problematic. Here, the residual adhesion required by the market in the range of at least less than 100 ppm is usually not achieved. This becomes obvious when using recycled materials, namely due to gel or yellowish substances in the film. Other serious consequences are gas precipitation during pellet extrusion or further processing in LSP (liquid state polymerization), which condenses PET under high vacuum.

[0005] The inadequate results of merely "clean" purification compared to "high purity" limit the use of recyclates and thus their marketing. At the same time, the requirements for polymer quality are also increasing, namely on a par with those for primary plastics. Products consisting of recyclates must be largely free of color impurities, various VOCs that aggravate degassing in the extruder and melt filtration, and foreign contamination, since these remaining impurities can lead to adverse changes in the polymer properties in machinery and processing as well as undesirable color changes and odor changes.

[0006] A method for separating cellulose and other adhering substances when recycling waste plastics, in particular mixed plastics, is known from EP2094462B1, wherein films and lumps of thicker plastic parts in pre-sorted plastic waste are mechanically pre-comminuted into fragments or particles of a predetermined size, and the comminuted material is fed into a disc refiner together with water without the fragments having to be compacted or agglomerated beforehand. The dirt is largely wiped off the fragments by the cooperating discs of the disc refiner and is then present as separate materials that can be separated from the plastic parts by suitable separation methods. A similar method is known from EP2094461B1.

[0007] With these known methods, satisfactory main cleaning of the plastic waste can be achieved in most cases. However, the toothed disc refiners used here are not very suitable for pre-cleaning of the plastic waste. However, pre-cleaning is precisely decisive for the final result of the cleaning process. In the case of strong fluctuations in the input concentration of plastic waste and water, this can also lead to an uneven distribution of the fragments and therefore not always complete cleaning.

[0008] Another method of using a disc refiner to remove dirt from plastic fragments is known from EP2734302B1. Here, the disc refiner is not a toothed disc refiner, but a plurality of cleaning ribs extending between the inner edge and the outer edge of the cleaning surface are respectively provided on the cleaning surface of the cleaning disc, wherein a plurality of cleaning strips extending transversely to the extension direction of the cleaning ribs are arranged between at least some mutually adjacent cleaning ribs. At least one side of the cleaning rib is inclined or bent relative to the axial direction of the corresponding cleaning disc, and the cleaning strips rise in a ramp shape and have a height smaller than the cleaning ribs. In this way, a small mechanical load on the plastic fragments is achieved during cleaning, and the plastic fragments are pulled between the discs, especially between the cleaning ribs, and the bending, wrinkling or entanglement of the plastic fragments that may cause insufficient cleaning is avoided. This method is also particularly suitable for the main cleaning of plastic fragments.

[0009] Furthermore, EP 3 057 751 B1 also discloses a device and a method for cleaning plastics, in particular plastic fragments, in plastic recycling. A toothed disc refiner is used, which has a central inlet for feeding the plastic to be cleaned into the working gap and an outlet for the cleaned plastics, wiped-off dirt and water arranged at the outer edge of the working gap. The outlet has a discharge pipe, through which water flowing laterally beside the working gap and directed tangentially to the working gap is pumped during operation, which exerts a suction effect on the working gap, thereby conveying the cleaned plastics into the discharge pipe. In this way, in addition to the input concentration and the cleaning concentration, the output concentration can also be set flexibly, in particular independently of the cleaning concentration. It is thus possible, in terms of maximum energy efficiency and cleaning effect, to set a high solids concentration in the working gap and at the same time to set a well-conveyable or pumpable suspension with a low solids concentration after the working gap.

[0010] The above-described method and device are particularly suitable for the main cleaning of plastic waste. The method and device are only limitedly suitable for pre-cleaning. Problems also arise in the case of fluctuating input concentrations, that is, in the case of fluctuating solid content of the plastic waste when it is fed into the working gap together with a process liquid such as water. In these cases, an uneven distribution of the plastic waste may occur, which in turn has an undesirable effect on the cleaning result. Summary of the invention

[0011] Based on the explained prior art, the object of the present invention is therefore to provide a toothed disc cleaner for pre-cleaning pre-shredded plastic waste, which toothed disc cleaner enables reliable and complete pre-cleaning at all times.

[0012] The invention achieves this object by the subject matter of independent claim 1. Advantageous embodiments are revealed in the dependent claims, the description and the drawings.

[0013] The invention achieves this object with a toothed disk cleaner of the type mentioned in the introduction in that the width of the working gap narrows radially outwards in a first section starting from the inlet and is constant in a second section arranged radially outside the first section.

[0014] As mentioned at the beginning, the toothed disc cleaner is used for pre-cleaning pre-crushed plastic waste, such as plastic fragments or plastic fragments crushed by plastic film. In principle, plastic fragments can be produced by crushing thin-walled hard plastic or film. The dirt to be removed can be surface adhesion, such as cellulose, label residues, organic pollutants, etc. The toothed disc cleaner according to the present invention includes two cleaning tools facing each other, which can be cleaning discs, for example. At least one of the cleaning tools is driven rotationally by means of a rotary drive, so that relative rotation is achieved between the cleaning tools. The cleaning tools each have a working surface with cleaning teeth. The working surface is configured to be annular, especially to be configured to be annular, wherein an annular, especially annular working gap is defined between the mutually opposed working surfaces. The cleaning teeth of the opposing working surfaces are mutually spaced and engaged with each other. Therefore, the cleaning tool forms a positive tool and a negative tool. The teeth on the working surface are single teeth, that is, these teeth are not connected to each other by ribs, etc. It is possible that the cleaning tools are mutually adjusted in the axial direction by means of corresponding adjustment devices, thereby being able to set the width of the working gap. The pre-cleaning gap is formed by the distance between the cleaning teeth, in particular the distance between the side tooth surface and the top surface of the cleaning teeth.

[0015] As explained, the toothed disc cleaner according to the present invention is used for pre-cleaning pre-crushed plastic waste. Therefore, the focus is not on the surface of the plastic waste to produce friction, but on the formation of a suspension by the plastic waste and the exfoliated pollutants, such as paper labels, to form the cellulose fibers that are broken. Accordingly, there is a distance between the teeth that mesh with each other. This distance can exist in every possible axial position, that is, also in the case of the settable minimum width of the working gap, so that the teeth of the opposing cleaning tools, especially their tooth surfaces, will never directly contact. It is conceivable that the cleaning tool can be set so that, for example, the top surface of the cleaning tooth can contact the bottom of the opposing cleaning tool, rather than contacting the side tooth surface of the cleaning tooth. Thus, the plastic waste to be pre-cleaned is forced onto the tooth surface, so that the pre-cleaning result can be improved. The rotation axis of at least one rotatably driven cleaning tool, especially the cleaning disc, can be the symmetry axis of the cleaning tool, especially the cleaning disc at the same time. As a rotary drive, for example, an electric drive is considered.

[0016] Furthermore, in the case where the cleaning tool is designed as a cleaning disc, the toothed disc cleaner has an inlet opening centrally into the working gap, in particular in the axial direction of the cleaning disc which simultaneously forms the axis of rotation. An input device is provided for inputting the plastic waste to be cleaned into the working gap through the inlet. The input device can supply the plastic waste together with a process liquid, such as water, into the working gap. For this purpose, a corresponding liquid supply device can be provided. However, it is also possible to supply the process liquid, such as water, into the working gap separately by means of a separate liquid supply device.

[0017] After being input into the working gap, the plastic waste is pre-cleaned between the mutually opposed working surfaces in the working gap. Here, the plastic waste, such as plastic fragments, is sheared between the cleaning tools and evenly distributed in the working gap in this way. Here, the plastic waste passes through the tooth row formed by the cleaning teeth, wherein this causes, for example, the film package or the fiber, such as the rope, to form a suspension with the organic adhesion. For example, the surface of printing ink or metallization is not or only slightly peeled off during the pre-cleaning process, but may be cellulose or the like. During the cleaning process, the plastic waste is radially transported outward from the central inlet in the working gap and reaches the outlet arranged on the outer edge of the working gap, through which the plastic waste is discharged together with the organic adhesion and process liquid that fall off for further processing, especially the main cleaning.

[0018] According to the present invention, the width of the working gap narrows outwardly in the radial direction in the first section starting from the central inlet and the width of the working gap is constant in the second section arranged radially outside the first section. The first section and the second section can be, in particular, the first annular section and the second annular section. The input area formed by the first section is used to receive the amount of material consisting of plastic waste at the inlet. Here, even if the input concentration, i.e. the proportion of plastic waste per time unit and / or per process liquid volume, fluctuates significantly, the working gap that is first wider in the first section and then narrows outwards also leads to homogenization and uniform distribution of plastic waste. This homogenization and uniform distribution are decisive for the subsequent cleaning effect. Only when the plastic waste is transported outward toward the outlet as evenly and individually as possible along the tooth row formed by the opposing cleaning teeth, can the best cleaning be achieved.

[0019] The second section with a constant working gap width is also of decisive importance here. Only the combination of a narrowed first section and a constant second section leads to the best cleaning result by carrying out the required homogenization and equalization of the plastic waste in the first section and achieving sufficient physical loading of the plastic waste in the second section with a constant working gap width for an optimal cleaning effect. In this way, the plastic waste, in particular plastic fragments, are oriented parallel to the tooth flanks of the cleaning teeth in the input zone formed by the first section, thereby avoiding accumulation or agglomeration of the plastic waste that would be harmful to cleaning. The required treatment of the plastic waste for pre-cleaning takes place in the working zone formed by the second section.

[0020] In particular, plastic fragments resulting from plastic films are difficult to dose for cleaning, since they have a high dry and wet volume at a low bulk density. Due to the design according to the invention with the first section and the working gap of the input zone formed thereby, the cleaning tool can also easily receive, for example, sinusoidally oscillating dosages without, for example, clogging. Here, too, sandwich packets or film packets resulting, for example, from the comminution of plastic films can be reliably identified by the design according to the invention of the working gap.

[0021] In the pre-cleaning process, in particular, organic adhesion or cellulose is peeled off from plastic waste without causing significant destruction of plastic waste, which can make subsequent separation of suspension components and main cleaning much more difficult. The pre-crushing of plastic waste is especially meaningful, because by unfolding the plastic fragments folded into an accordion shape and breaking the film package into multiple individual fragments according to the cleaning tool of the present invention, it is possible to cause the plastic waste of extended pre-crushing. In practice, for example, the average particle size of the pre-crushed plastic waste not more than 50 mm is confirmed to be in line with the purpose. For example, the fragment size of not more than twice the height of the cleaning teeth is suitable. Utilizing the toothed disc cleaner according to the present invention, the cleaning result with less than 200 ppm of external residual contamination of plastic waste can be achieved in the pre-cleaning process. The high purity currently required for recyclables can be reliably achieved by the subsequent main cleaning.

[0022] As explained, a process liquid, such as water, is usually additionally supplied to the working gap. Due to the inventive design of the toothed disc cleaner, significantly lower process liquid temperatures and a substantial reduction in the use of NaOH or surfactant mixtures are possible compared to the prior art.

[0023] According to one embodiment, the second section can be directly connected to the first section. In this way, the transition between the input area formed by the first section and the working area formed by the second section is optimized.

[0024] According to another design, the second section can extend to the outer edge of the working gap. The first section and the second section can cover the entire working gap together. However, it is also conceivable that, for example, an inlet section is provided between the inlet and the first section, on which no cleaning teeth are arranged, for example.

[0025] The working surfaces of the cleaning tool with the cleaning teeth can be arranged conically in the first section and arranged parallel to each other in the second section. In this way, the first and second sections can be constructed in a particularly simple manner.

[0026] According to a further embodiment, the cleaning teeth can be arranged at a greater mutual distance on a surface section of the working surface of the cleaning tool forming the first section than on a surface section of the working surface of the cleaning tool forming the second section. The density of the cleaning teeth per unit area is therefore lower in the first section than in the second section. This further simplifies the entry of the plastic waste and further improves the homogenization and equalization and separation of the plastic waste, while in the working area formed by the second section a particularly effective pre-cleaning is carried out by the cleaning teeth arranged narrowly relative to one another.

[0027] The cleaning teeth of the cleaning tool can have the shape of shark fins in the side view. In addition, it can be provided that the tooth surface of the cleaning tooth of the cleaning tool that precedes during the relative rotation of the cleaning tool is arranged at an angle between 30° and 60° relative to the working surface that carries the cleaning teeth respectively. It can also be provided that the tooth surface of the cleaning tooth of the cleaning tool that follows during the relative rotation of the cleaning tool is arranged at an angle between 70° and 90° relative to the working surface that carries the cleaning teeth respectively. If it is said that the tooth surface of the cleaning tooth of the cleaning tool is preceded or followed, it involves the relative rotation of the cleaning tool, so that for example, the cleaning tool (stator) driven non-rotatingly also has the tooth surface of the precedence and the tooth surface of the follow-up due to the relative rotation relative to the opposing, rotating cleaning tool (rotor). Here, the angle relative to the working surface is measured in the shortest direction respectively. Through the design of the cleaning teeth, especially the flatter inclined portion of the tooth surface of the precedence, a particularly effective pre-cleaning is achieved while optimizing the energy consumption of the toothed disc cleaner. Therefore, the inclined design scheme leads to extended surface contact of flexible plastic waste, especially plastic fragments, which are oriented in parallel in the second section, i.e., the working area, in an advantageous manner and thus leads to effective pre-cleaning. In this way, a pumping action can also be generated in a targeted manner, which effectively transports plastic waste from the inlet through the working gap to the outlet, especially conveying plastic waste outward from tooth ring to tooth ring in sequence. The cleaning teeth moving through the suspension composed of plastic waste and cleaning liquid produce a flow determined by their shape. The inclined design scheme of the above-mentioned tooth surface can generate a pumping action in a targeted manner. The energy requirement of the toothed disc cleaner can also be reduced by the optimal fluid dynamics of the tooth surface.

[0028] According to another design, at least one radially outer side tooth surface of the cleaning tooth can be configured obliquely relative to the working surface carrying the cleaning tooth respectively. In addition, the mutually opposite side tooth surfaces of the mutually meshing cleaning teeth can be spaced parallel to each other. Correspondingly, the corresponding opposite, that is to say radially inner side tooth surfaces of the cleaning teeth can also be configured obliquely relative to the working surface. The side tooth surfaces of the cleaning teeth can be configured, for example, mirror-symmetrically to each other, especially at least one rotation position of the cleaning tool. The inclined arrangement can exist, for example, at an angle between 10° and 30° measured again in the shortest direction relative to the corresponding working surface. The cleaning teeth of the cleaning tool can have the same height. This is correspondingly applicable to two cleaning tools, wherein the cleaning teeth of the two cleaning tools can also have the same height. The cleaning teeth form a line so that plastic waste, especially plastic fragments, can be oriented parallel to the side tooth surfaces of the cleaning teeth. By the aforementioned design of the lateral tooth surfaces of the cleaning teeth, the pumping effect can be further improved on the one hand. On the other hand, the cleaning effect can be further optimized.

[0029] At least one of the edges between the leading tooth flank and the trailing tooth flank and the side tooth flank and / or at least one of the edges between the leading tooth flank and the trailing tooth flank and / or the side tooth flank and the top surface of the cleaning tooth can be rounded. The above-mentioned advantageous effect is further enhanced thereby, wherein friction, which is not primarily desired, is reduced, especially during pre-cleaning.

[0030] According to a further embodiment, the cleaning tool can be a high-quality steel casting. High-quality steel casting, for example based on an alloy with a high Brinell hardness, produces a relatively rough surface, especially of the cleaning teeth, due to the process. In particular, when casting high-quality steel, the hardness of the surface is so high that mechanical stresses due to plastic waste do not lead to a loss of roughness. This ensures that the cleaning teeth can still perform their cleaning function even over a long period of time.

[0031] As mentioned above, at least one of the cleaning tools, preferably both cleaning tools, can be a cleaning disc. The cleaning disc can be configured as a circular ring, for example. The cleaning disc can be composed of a plurality of circular ring segments, for example. The axial direction then simultaneously constitutes the rotation direction of at least one cleaning disc. The inlet can lead into the working gap along the axial direction of at least one cleaning disc.

[0032] According to another design, it can be provided that the input device includes a liquid supply device, through which liquid can be directly supplied to the input device, and / or the working gap is equipped with a liquid supply device, through which liquid can be directly supplied to the working gap. The input device can, for example, include a conveying screw that conveys plastic waste to the inlet. With the help of the liquid supply device of the input device, a process liquid, such as water, can be directly introduced into the input device, for example, into the screw groove of the conveying screw, especially through a suitable nozzle. However, as explained, it is also conceivable that the working gap is equipped with a liquid supply device, through which liquid can be directly supplied to the working gap. For example, the conveying screw can be constructed as a hollow shaft screw and the process liquid, such as water, is directly introduced into the working gap through the hollow shaft. Of course, additionally or alternatively, other input possibilities for the process liquid, in particular other nozzles for direct introduction into the working gap, are also possible.

[0033] The present invention also achieves this object by using the toothed disc cleaner according to the present invention for pre-cleaning plastic fragments pre-crushed by plastic film. The toothed disc cleaner according to the present invention is particularly suitable for pre-cleaning plastic fragments pre-crushed by plastic film. A cleaning result of pre-cleaning with less than 200 ppm of foreign residual contamination can already be achieved. It is important here to maintain a suitable solid concentration in the working gap in the plastic fragments pre-crushed by the plastic film, for example less than 5% (weight). In the case of PET or hard plastics in material transportation, the solid concentration can be selected to be slightly higher, for example not more than 10% (weight). In addition, it is meaningful to discharge the process liquid immediately, so as to avoid back-contamination caused by the excessively long retention of the cleaned plastic waste. As described, in the application according to the present invention of the toothed disc cleaner according to the present invention, a particle size of no more than 50 mm of the pre-crushed plastic waste has proven to be practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The following is a more detailed description of an embodiment of the present invention with reference to the accompanying drawings. Schematically shown:

[0035] Figure 1 A cleaning disc of a toothed disc cleaner according to the invention is shown in a three-dimensional view,

[0036] Figure 2 Shown in top view Figure 1 Cleaning tray in

[0037] Figure 3 shows a cross-sectional view along a toothed disc cleaner according to the invention, and

[0038] Figure 4 Two detail views of a cleaning disk of a toothed disk cleaner according to the invention are shown.

[0039] Figure 5 A schematic partial sectional view shows a toothed disc cleaner according to the invention,

[0040] Figure 6 Show according to Figure 5 A toothed disc cleaner having an input device for inputting plastic waste to be cleaned according to a first embodiment,

[0041] Figure 7 Show according to Figure 5 A toothed disc cleaner having an input device according to a second embodiment for inputting plastic waste to be cleaned,

[0042] Figure 8 Show according to Figure 5 A toothed disc cleaner having an input device according to a third design for inputting plastic waste to be cleaned, and

[0043] Fig. 9 A toothed disc cleaner according to the invention is shown in a schematic sectional illustration with an outlet opening according to a further exemplary embodiment. DETAILED DESCRIPTION

[0044] Unless otherwise indicated, the same reference numerals in the figures denote the same objects.

[0045] exist Figure 1 and Figure 2 1 shows a cleaning tool 10 of a toothed disc cleaner according to the present invention, which in the present case is a circular ring-shaped cleaning disc 10, which can also be composed of a plurality of circular ring segments, for example. The cleaning disc 10 has a circular ring-shaped working surface 12, on which a plurality of cleaning teeth 14 are arranged. The cleaning disc 10 forms an inlet 16 for plastic waste to be pre-cleaned, for example, plastic fragments made of pre-crushed plastic film, in the center. The outlet 18 for pre-cleaned plastic waste is constructed at the outer edge of the cleaning disc 10. An input device for inputting plastic waste to be cleaned is connected to the inlet. The input of plastic waste can be carried out together with a process liquid, such as water, for example.

[0046] exist Figure 1 and 2 The cleaning plate 10 shown in the figure is used as a lower cleaning plate 10 and an upper cleaning tool 20, here the upper cleaning plate 20. Figure 3. The upper cleaning disc 20 is also designed in an annular shape and has an annular working surface 22. On the working surface 22 of the upper cleaning disc 20, there are a plurality of cleaning teeth 24. By means of a rotary drive, at least one of the cleaning discs 10, 20 can be driven rotationally about its axis, thereby generating a corresponding relative rotation between the cleaning discs 10, 20. The upper cleaning disc 20 is constructed to the greatest extent identical to the lower cleaning disc 10, with the difference that the tooth rows formed by the cleaning teeth 24 are respectively arranged radially offset relative to the tooth rows formed by the cleaning teeth 14 of the lower cleaning disc 10, so that the cleaning teeth 14 and 24 mesh with each other at a distance from each other, as shown in FIG. Figure 3 This can be seen in Figure 3 It can also be seen that the mutually opposing side tooth surfaces 26, 28 of the mutually meshing cleaning teeth 14, 24 are spaced parallel to each other. It can also be seen that the side tooth surface 26 of the cleaning tooth 14 and the side tooth surface 28 of the cleaning tooth 24 are respectively configured to be mirror-symmetrical and are arranged obliquely, for example, at an angle between 10° and 30° relative to the working surface 12 or 22 carrying the cleaning tooth 14 or 24, respectively.

[0047] In addition, Figure 3 In particular, it can be seen that, starting from the inlet 16, the working surfaces 12 and 22 of the cleaning discs 10 and 20 extend conically in a radial direction outwardly toward each other in a first section, so that the working gap formed between the working surfaces 12, 22 narrows in the radial direction outwardly from the inlet 16 in this first section. In a second section, which is adjacent to the first section and continues to the outlet 18, the working surfaces 12 and 22 of the cleaning discs 10 and 20 are arranged parallel to each other, so that the width of the working gap is constant in this second section. Figure 2 For the sake of clarity, the reference numeral 30 is used to illustrate the Figure 2 In the embodiment of the present invention, a circular separation line is formed between a first radially inner section and a second radially outer section. Figure 1 and Figure 2 It can be seen that the cleaning teeth 14 are arranged at a greater distance from each other on the outer surface section of the working surface 12 forming the first section than in the outer surface section of the working surface 12 forming the second section. Therefore, the tooth density of the cleaning teeth 14 is smaller in the first section than in the second section. This is also provided in the upper cleaning disc 20.

[0048] according to Figure 4 The design of the toothed disc cleaner according to the present invention should be described in more detail. Figure 4 The right side view of FIG. 1 , in which only a section through the lower cleaning disk 10 is shown, shows the cone angle 32 of the conical arrangement of the working surface 12 or 22 in the first section. Figure 4 The left view is along Figure 4In particular, one of the cleaning teeth 14 can be seen in the sectional view, wherein the cleaning teeth 14 are located at the bottom of the cleaning teeth 14. Figure 4 In the left side view of the figure, the direction of rotation of the cleaning disc 10 extends from left to right. The tooth surface 34 of the cleaning tooth 14 leading during the relative rotation of the cleaning discs 10, 20 relative to each other is arranged at an angle 36 of between 30° and 60°, in the present case about 45°, relative to the working surface 12. The tooth surface 38 of the cleaning tooth 14 trailing during the relative rotation of the cleaning discs 10, 20 is arranged at an angle 40 of between 80° and 90°, in the present case about 85°, relative to the working surface 12. The top surface 42 of the cleaning tooth 14 can be configured parallel to the working surface 12.

[0049] The edges between different surfaces of the cleaning teeth 14, in particular between the leading and trailing tooth surfaces 34, 38 and the top surface 42 and / or between the leading and trailing tooth surfaces 34, 38 and the side tooth surfaces 26 and / or between the side tooth surfaces 26 and the top surface 42, can be rounded. Here, all cleaning teeth 14 and 24 can be configured as in Figure 4 This is shown by way of example for one of the cleaning teeth 14 .

[0050] It should also be mentioned that the cleaning disks 10 , 20 can each be produced as a high-quality steel casting.

[0051] exist Figure 5 In the embodiment, the cleaning discs 10, 20 can be, for example, as described in Figures 1 to 4 As described, the cleaning discs are arranged in a manner rotatable relative to each other in the cleaning device housing 44. During operation, the rotary drive 46 can, for example, drive the cleaning disc 20 in rotation via the rotary shaft 48, so that the cleaning discs 10, 20 rotate relative to each other. The working gap between the cleaning discs 10, 20 can be set by the adjusting device 50 including the adjusting drive 52 and the adjusting element 54.

[0052] With the help of Figures 6 to 8 The different possibilities for feeding the plastic waste to be pre-cleaned into the toothed disc cleaner shall be described. Figure 6 In the embodiment of the present invention, the input comprises an input screw 58 driven by a screw drive 56, to which the plastic waste 62 to be pre-cleaned is supplied via an inlet 60 on the one hand and a cleaning liquid 66, such as water, is supplied by means of a pump 64 on the other hand. The cleaning liquid can in principle be fed via the screw input or can also be added to the input screw 58 via a plurality of inlets downstream of the inlet via the hollow shaft of the input screw 58 and / or via an input nozzle in the cleaner housing 44. The input screw 58 conveys the plastic waste 62 together with the cleaning liquid 66 centrally into the working gap formed between the cleaning discs 10, 20. The pre-cleaned plastic waste is discharged via the outlet 18 for further processing, such as in Figure 6 As shown in the figure numeral 68.

[0053] according to Figure 7 Embodiments and basis Figure 6 The embodiment of the embodiment of the present invention differs only in that an inlet funnel 70 is provided instead of the inlet screw 58, which has a plurality of inlet nozzles 72 arranged, for example, at regular intervals on its upper edge. The cleaning liquid 66 supplied by the pump 64 is introduced into the inlet funnel 70 through the inlet nozzles 72, for example, as a liquid jet into the inner wall of the inlet funnel 70, in which the supplied plastic waste 62 is located. Through the connection 74, the plastic waste 62 together with the cleaning liquid 66 is again supplied centrally to the working gap between the cleaning discs 10, 20. Such an inlet device is known, for example, from EP3423203B1.

[0054] In accordance with Figure 8 In the embodiment of the present invention, an input tank 76 is provided, which has a stirring device 78 arranged therein, into which the plastic waste 62 and the cleaning liquid 66 are supplied. The plastic waste 62 and the cleaning liquid 66 are stirred in the input tank 76. The plastic waste 62 mixed with the cleaning liquid 66 is supplied centrally by a pump 80 to the working gap between the cleaning discs 10, 20, as in Figure 8 As shown at 82 in FIG.

[0055] exist Fig. 9 The outlet of the toothed disc cleaner according to the invention is shown by way of example in Fig. 9 In FIG. 4 , only the cleaner housing 44 of the toothed disc cleaner is shown in section with an outlet. Fig. 9 The design shown in corresponds to the design described in EP3057751Bl, for example. Fig. 9 The exemplary embodiments of can be combined with any of the exemplary embodiments explained above.

[0056] In the example shown, the discharge pipe 84 is connected tangentially to the outlet 18 of the toothed disc cleaner with respect to the working gap between the cleaning discs 10, 20. The discharge pipe 84 can be connected directly or via a further pipe to a separation device via a flange 86, in which the pre-cleaned plastic is separated from the dirt wiped off in the working gap. In the example shown, at the end of the discharge pipe 84 facing away from the flange 86 or the separation device, a nozzle pipe 88 is connected to a pump 90, in particular a liquid pump 90, for example a water pump 90, such as a centrifugal pump.

[0057] During the operation of the toothed disc cleaner, the plastic pre-cleaned in the working gap is transported by centrifugal force together with the scraped dirt and cleaning liquid through the outlet 18 to the discharge pipe 84. At the same time, a liquid such as water is introduced into the discharge pipe 84 through the nozzle pipe 88 along the conveying direction of the suspension discharged from the working gap toward the separation device in the form of a directional liquid jet by the liquid pump 90, such as Fig. 9 92 in the figure. The liquid jet thus directed extends tangentially to the working gap, just like the discharge pipe 84. The liquid jet conveys the mixture of cleaning liquid and pre-cleaned plastic in the discharge pipe 84 and the wiped-off dirt further to the separation device, such as in Fig. 9 94. Here, the liquid jet exerts a suction effect on the working gap according to the principle of a jet pump in such a way that a suspension consisting of pre-cleaned plastic, wiped-off dirt and cleaning liquid is sucked from the working gap into the discharge pipe 84. At the same time, the output concentration, i.e. the concentration in the discharge pipe 84, can be set in a suitable manner by the liquid jet. In this regard, no solids pump or pump sump is required. Reference numerals list

[0058] 10. Cleaning plate

[0059] 12 working surface

[0060] 14 Cleaning teeth

[0061] 16Entrance

[0062] 18Exit

[0063] 20 Cleaning tray

[0064] 22 working surface

[0065] 24 cleaning teeth

[0066] 26 side tooth surface

[0067] 28 side tooth surface

[0068] 30 separation line

[0069] 32 cone angle

[0070] 34 Leading tooth surface

[0071] 36 Angle

[0072] 38 Rear tooth surface

[0073] 40 degrees

[0074] 42 Top

[0075] 44 Cleaner housing

[0076] 46 Rotary drive

[0077] 48 Rotation axis

[0078] 50Regulators

[0079] 52 Adjustment drive

[0080] 54Regulator

[0081] 56 screw drive

[0082] 58 Input screw

[0083] 60 entrance openings

[0084] 62 Plastic waste

[0085] 64 Pumps

[0086] 66 cleaning fluid

[0087] 68 Arrow

[0088] 70 Input Funnel

[0089] 72 Input Nozzle

[0090] 74 connection part

[0091] 76 Input tank

[0092] 78 stirring device

[0093] 80 pumps

[0094] 82 Arrow

[0095] 84 discharge pipe

[0096] 86 flange

[0097] 88 nozzle tube

[0098] 90 pumps

[0099] 92 Arrow

[0100] 94 Arrows

Claims

1. A toothed disc cleaner for pre-cleaning pre-shredded plastic waste, in particular plastic flakes, in a plastic recycling process, the toothed disc cleaner comprising two cleaning tools (10, 20) facing each other, at least one of which is driven in rotation by means of a rotary drive (46), wherein: Each of the cleaning tools (10, 20) has a working surface (12, 22) provided with cleaning teeth (14, 24), wherein an annular working gap is defined between the working surfaces (12, 22) facing each other for pre-cleaning plastic waste, and wherein the cleaning teeth (14, 24) of each of the facing working surfaces (12, 22) mesh with each other at a distance from each other, the toothed disc cleaner also includes an inlet (16) leading centrally into the working gap, the inlet having an input device for inputting plastic waste to be cleaned, and the toothed disc cleaner includes an outlet (18) arranged on the outer edge of the working gap, through which the plastic waste pre-cleaned in the working gap is discharged, characterized in that the width of the working gap narrows radially outward in a first section starting from the inlet (16), and the width of the working gap is constant in a second section arranged radially outside the first section.

2. The toothed disc cleaner according to claim 1, characterized in that: The second section is directly connected to the first section.

3. A toothed disc cleaner according to any one of the preceding claims, characterised in that The second section extends as far as the outer edge of the working gap.

4. A toothed disc cleaner according to any one of the preceding claims, characterised in that The working surfaces (12, 22) of the cleaning tools (10, 20) having the cleaning teeth (14, 24) are arranged conically in the first section and parallel to one another in the second section.

5. A toothed disc cleaner according to any one of the preceding claims, characterised in that The cleaning teeth (14, 24) are respectively arranged at a greater distance from each other on a surface section of the working surface (12, 22) of the cleaning tool (10, 20) forming the first section than on a surface section of the working surface (12, 22) of the cleaning tool (10, 20) forming the second section.

6. A toothed disc cleaner according to any one of the preceding claims, characterised in that The tooth surfaces (34) of the cleaning teeth (14, 24) of the cleaning tool which advance during the relative rotation of the cleaning tools (10, 20) are arranged at an angle (36) between 30° and 60° relative to the working surfaces (12, 22) respectively carrying the cleaning teeth (14, 24).

7. A toothed disc cleaner according to any one of the preceding claims, characterised in that The tooth surfaces (38) of the cleaning teeth (14, 24) of the cleaning tool that travel backward during the relative rotation of the cleaning tools (10, 20) are arranged at an angle (40) between 70° and 90° relative to the working surfaces (12, 22) that respectively carry the cleaning teeth (14, 24).

8. A toothed disc cleaner according to any one of the preceding claims, characterised in that At least one radially outer side tooth flank (26, 28) of the cleaning tooth (14, 24) is configured to be inclined relative to a working surface (12, 22) respectively carrying the cleaning tooth (14, 24).

9. A toothed disc cleaner according to any one of the preceding claims, characterised in that The mutually opposing side tooth surfaces (26, 28) of the mutually meshing cleaning teeth (14, 24) are spaced apart from each other in parallel.

10. A toothed disc cleaner according to any one of the preceding claims, characterised in that The cleaning tools (10, 20) are high-quality steel castings.

11. A toothed disc cleaner according to any one of the preceding claims, characterised in that At least one of the cleaning tools (10, 20) is a cleaning disc (10, 20).

12. The toothed disc cleaner according to claim 11, characterized in that: The inlet (16) opens into the working gap in the axial direction of the at least one cleaning disk (10, 20).

13. A toothed disc cleaner according to any one of the preceding claims, characterised in that The inlet means comprises a liquid supply means, by means of which liquid can be supplied directly into the inlet means, and / or the working gap is provided with a liquid supply means, by means of which liquid can be supplied directly into the working gap.

14. Use of a toothed disc cleaner according to any one of the preceding claims for pre-cleaning plastic fragments pre-shredded from plastic films.

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