Sieve device for separating contaminants from a suspension

Abstract

The invention relates to a sieve device (1) with at least one retention element (3, 13, 4, 14) for cleaning a suspension of contaminants, wherein the sieve device (1) comprises a shaft that can be driven rotatorily by a drive, wherein at least one retention element extends radially from the shaft, wherein flowable spaces (8) are formed by the at least one retention element (3, 13, 4, 14) and a sieving effect is provided by the flowable spaces (8).

Description

[0001] The invention relates to a sieving device for separating contaminants from a suspension. The invention particularly relates to a sieving device for use in fiber processing, wherein the sieving device is used to filter out contaminants with a predetermined minimum dimension.

[0002] When processing waste paper, all types of impurities must be expected. Larger impurities are currently retained and removed from the process along with smaller impurities by the same separation element, particularly during screen separation in a horizontal high-pressure pulper. In such a pulper, pulping occurs in a trough with a horizontal axis of rotation of a shaft when the paper density exceeds 10% by weight. The dimensions of the working elements for generating a suspension must be designed accordingly. Such a pulping device is known, for example, from WO24079177 A1.

[0003] CN 111235934A discloses a continuously operating system for low-concentration suspensions for the separation of contaminants. The system comprises a sedimentation tank whose bottom is equipped with a contaminant trap for removing coarse, heavy contaminants, and whose lower portion is designed to continuously receive suspension fed from a low-concentration solvent, often also referred to as a pulper. A discharge for the desired material is provided downstream of the contaminant trap. A device for removing light contaminants is provided at the top of the sedimentation tank. Suspension containing light contaminants is discharged from the top of the sedimentation tank, downstream of the discharge for the desired material.

[0004] The object of the invention is to increase operational reliability by separating contaminants, particularly those of large volume. This separation should be cost-effective. In particular, the invention should ensure the separation of contaminants with predetermined minimum dimensions and prevent, or at least reduce, clogging of the sieve device by these contaminants.

[0005] The problem is solved according to the invention by an embodiment according to the independent claim. Further advantageous embodiments of the present invention are found in the dependent claims.

[0006] Operational reliability can be increased by using a simple, cost-effective sieve device to separate larger impurities, especially those with dimensions larger than a predetermined size.

[0007] A rotating shaft with retaining elements extending radially and circumferentially along the shaft provides a screening device that reduces the risk of clogging. The retaining elements act as sieves and restrict the flow of large contaminants whose dimensions prevent them from passing through the spaces between them.

[0008] In a preferred embodiment, the spaces between the elements are designed to allow flow transversely to the shaft. In conjunction with the axial extent of the shaft, two broad faces are defined. When the flow is transverse to the shaft, it travels from one broad face to the opposite broad face of the shaft equipped with retaining elements. The flow passes through the spaces between the retaining elements.

[0009] Particularly in a horizontal high-pressure pulper used in fiber processing, the operational reliability of a downstream sorting unit can be increased by separating contaminants with dimensions larger than 80 to 100 mm. This makes it possible to use smaller working elements in the sorting unit. Wear caused by large contaminants can be avoided. In a preferred embodiment, the dimensions of the flowable spaces are less than 100 mm, and in particular less than 80 mm, in both the axial and radial directions.

[0010] In a preferred embodiment, it is provided that the spaces between are perpendicular to the shaft and can be flowed through.

[0011] Contaminants that accumulate on the retaining element(s) can be removed by at least one stationary scraper associated with the element(s). The scraper is adjacent to the retaining element(s). If contaminants have accumulated on the edge of a retaining element, the scraper cleans the edge. The scraper can be rib-shaped and only encloses a portion of the retaining element's circumference. Alternatively, the scraper can be in contact with an edge of the retaining element(s).

[0012] In a preferred embodiment, the wiper(s) have an axial extent that is / are smaller than the axial extent of the retaining element. It has proven particularly advantageous for the wiper to be shorter by at least the amount of the axial extent of the gap.

[0013] In a preferred embodiment, at least one spiral-shaped retention element is provided. By interacting with the at least one scraper, scraping can occur against the slope and direction of rotation of the spiral. This allows for effective separation of contaminants, preventing clogging of the sieve. The material to be filtered can flow through the spaces between the retention elements.

[0014] In a preferred embodiment, the at least one retaining element is spirally shaped. When the shaft rotates, the contaminants adhering to the boundary edge of the respective retaining element are conveyed axially. The conveying direction depends on the direction of rotation, the position of the scraper, and the orientation of the retaining element's slope.

[0015] It may be possible to selectively return these contaminants to the suspension during downward transport or to remove these contaminants from the suspension during axial upward transport out of the separator.

[0016] Depending on the dimensions and / or shape of the retention elements, the passage of contaminants can be controlled to meet predetermined maximum permissible dimensions. Contaminants that do not meet the predetermined maximum permissible dimensions in all three dimensions are also sometimes repelled by the retention element. The radial dimension and the circumferential shape of the retention element(s) play a role in this. If only one spiral-shaped retention element is provided, the fibrous material passes through the spiral of the element. The flow occurs at an angle other than 0° to the axial direction of the shaft. If disc-shaped elements are used as retention elements, the fibrous material passes through the spaces between them.

[0017] In a preferred embodiment, the at least one retaining element has axially spaced surfaces to form gaps. Each gap is formed by two axially adjacent surfaces of the retaining element(s).

[0018] In a preferred embodiment, a continuous drive is provided for the at least one shaft. This ensures the continuous removal of accumulated contaminants.

[0019] In a preferred embodiment, the at least one shaft is driven only temporarily. This allows for periodic drive of the shaft, drive dependent on the amount of contaminants in the suspension, or drive dependent on the shaft's drive torque. A high drive torque indicates a high amount of contaminants. Consequently, the system can switch to continuous rotary drive or to more frequent drive cycles to adapt to a high contaminant load. Conversely, the system can also adapt to a low contaminant load.

[0020] In a preferred embodiment, the radial extent of the retaining element or all retaining elements is the same. This makes sealing at the radial boundary edge particularly simple. It also ensures that the gaps have identical radial extents.

[0021] Alternatively, the dimensions can be designed to decrease or increase along the axial direction of the shaft. This allows the quality of the material being processed to be varied depending on the flow height. Different inflow pressures depending on the axial height of the shaft can also be compensated for by selecting the appropriate size of the gaps. For example, small gaps at the inflow level can be used to deliberately counteract a high flow rate and a short residence time in the separator.

[0022] In a preferred embodiment, the sieving device comprises a first shaft with at least one retaining element and a further shaft with at least one retaining element. The at least one retaining element of the first shaft engages in a gap of the at least one retaining element of the further shaft. This allows contaminants to be removed from the gaps of the at least one retaining element.

[0023] In a preferred embodiment, the shafts are designed to rotate at different speeds. This allows an additional shear moment to be generated.

[0024] In another embodiment, it is provided that the first shaft rotates in the opposite direction to the second shaft.

[0025] In a preferred application, it is provided that at least one shaft of the sieve device is arranged vertically in the reservoir.

[0026] In some applications, it has proven advantageous to delimit the material reservoir with both lateral and axial partitions. In a particularly preferred embodiment, it has proven advantageous to provide a radial free space between the retaining elements and the axial partition. It has proven advantageous to dimension this free space to between 0.5 and 0.3 times the axial extent of the gap. This minimizes the risk of contaminants becoming trapped in this area.

[0027] Furthermore, it has proven advantageous for the shaft with retaining elements or a spiral retaining element to have a greater axial extent than the extent of the material reservoir. In the case of a spiral retaining element, the axial projection should be at least ½ times the axial extent of the space 6.

[0028] The invention will be explained below with the aid of figures. The figures show, in detail: Fig. 1: Sieve device with a rotating shaft Fig. 2: Sieve device with two counter-rotating shafts Fig. 3: Vertical view of the sieve device Fig. 4: Horizontal HC pulper with sedimentation tank Fig. 5: Side view of the arrangement of two waves Fig. 6: Top view of a section showing two waves rotating in the same direction Fig. 7: Side view of the two waves Fig. 8: Counter-rotating waves in side view with debris Fig. 9: Shaft with disc-shaped retaining elements for a sieve device Fig. 10 separators with a sieve device for full immersion use Fig. 11 a: Schematic representation of a sieving device with a material reservoir in a vertical direction Fig. 11b: Separator according to Fig. 11a from a side perspective Fig. 12: Sketch of a sieve device with two shafts

[0029] In Fig. Figure 4 shows an arrangement 100 with a horizontal high-consistency (HC) pulper 110 for processing fibrous materials, in particular for forming a fibrous suspension. The arrangement 100 is particularly suitable for dissolving fibrous materials with high densities in the high-consistency (HC) range, and especially for recycled paper pulp. The HC pulper 110 comprises a front dissolving section 120 and a rear screen section 150 with a screen drum. The fibrous material is fed to the front dissolving section 120 via a feeder 130. The fibrous material is often fed in the form of recycled paper bales. For processing the fed fibrous material, movement of the fibrous material is required. For moving the fibrous material, working elements are provided on a shaft 2, whereby the fibrous material is moved by the working elements. A drive 140 is provided for driving the shaft.

[0030] The dissolving section 120 is designed for dissolving fibrous material, and the screening section 150 is designed for the subsequent sorting and removal of the fibrous suspension. Preferably, suspensions of different qualities are separated from one another in the screening section 150. A separator 170 is arranged between the dissolving section 120 and the screening section 150 for separating heavy particles such as wires, metal parts, plastic components, etc. The contaminants listed above as examples are usually fed in together with the fibrous material, which is supplied in bale form. Sedimented contaminants can be discharged from the separator 170 via the airlock 175.

[0031] The suspension discharged from the dissolution section 120 is fed to the separator 170 via a first channel 21 as feed 23 to a reservoir 25. Heavy particles can be separated in the reservoir 25 by sedimentation. From the reservoir 25, suspension is fed back to the screen section 150 via a second channel 31 as discharge from the reservoir.

[0032] In the following example according to Fig. 1 and Fig. In the embodiment shown, a screening device 1 is installed in a reservoir 25. This screening device 1 is a screening device with a shaft 2. Fiber suspension containing impurities is fed into the reservoir 25 via a first channel 21 as a feed 23. The reservoir 25 has a further channel 31 as a discharge 33 for fiber material. The screening device 1 is arranged upstream of the opening of the discharge 33. In the embodiment shown, a material reservoir 35 for the screened suspension is formed in the region of the inlet to the discharge 33. The material reservoir 35 is fed by the suspension passing through the screening device 1, with the outflow side 37 of the screening device 1 located in this reservoir 35.

[0033] The spiral-shaped retaining element 4 of the screening device 1 retains contaminants with dimensions exceeding the predetermined permissible limits. The shaft 2 can be driven rotaryally by a drive (not shown). The free axial distance 6 and the free radial distance 7 form an open space 8 for the flow of suspension. An axial limitation of the spaces is achieved by the shaft on one side and by partitions 9 radially adjacent to the retaining element or by a provided scraper. Contaminants with dimensions larger than the open spaces 8 are retained at the upstream side 27 of the screening device 1 and remain in the reservoir 25. This increases the concentration of contaminants on the upstream side 27 of the screening device 1.

[0034] Instead of wave 2, according to Fig. 2, with the spiral-shaped retaining element 4, the in Fig. The shaft shown in 9 is provided with disc-shaped retaining elements 3.

[0035] Smaller, flexible contaminants that remain stuck on the edges of the retaining element 3, 4 or on the edges of the partition 19 are scraped off by the interaction of the respective retaining element 3, 4 and a lateral partition as a scraper 5.

[0036] In Fig. 3 and Fig. 5 to Fig. Figure 8 shows a variant embodiment with a first shaft 2 with retaining elements 3 and a further shaft 12 with retaining elements 13. Instead of two shafts, a series of shafts with retaining elements could also be provided.

[0037] The retaining elements of the first shaft 2 project into the spaces between the retaining elements of the subsequent shaft 12. This minimizes the risk of contaminants becoming wedged between the retaining elements 3, 13 or the helical turns of a spiral retaining element 4, 14, and also removes any wedged contaminants. In particular, it is possible to operate with shafts 2, 12 rotating in opposite directions. Contaminants accumulating at the radial boundary edge of both spiral retaining elements 4, 14, especially smaller flexible contaminants, are pushed downwards against the spiral's pitch by the action of the respective scrapers 5 and 15 and removed from the respective retaining element 4, 14. The retention element engaging in the space 8 prevents the accumulation of small flexible contaminants 180 as a tangled mass.When shafts 2 and 12 are operated in opposite directions, retaining elements designed in a mirror image must be used on the shafts and shafts 2 and 12 are driven in opposite directions synchronously.

[0038] In Fig. 5, Fig. 7 and Fig. Figure 8 shows the arrangement of two shafts with spiral retaining elements 4, 14. Each retaining element 4, 14 engages in the space 8 between the other retaining element 14, 4. Fig. Figure 6 shows an operation with the shafts 2 and 12 rotating in the same direction. In this operating mode, two shafts 2 and 12 of identical construction with a spiral retaining element 4 and 14 can be used.

[0039] In Fig. 9, Fig. 11a, Fig. Figure 11b shows a sieve device with a shaft 2 for a separator. This sieve device can be used in a separator, where the sieve device can be completely immersed below the liquid / suspension surface. An axial partition 39 is provided on both axial sides of the material reservoir 35 to delimit it. A maximum distance 40 of 0.5 to 0.3 times the height and axial extent 6 of the respective adjacent space 8 is provided between the axial partition 39 and the retention element 4.

[0040] In Fig.Figure 12 shows a sieve device in which the retaining elements are driven in opposite directions. A separator can be provided centrally between the two shafts on the upstream side 27. Alternatively, a separator can be omitted, in which case the retaining element of the other shaft acts as the separator. The retaining elements can be arranged such that the respective spaces 8 are not equidistantly divided. Reference symbol list 1 sieve device 2nd wave 3 Retaining element(s) 4 Spiral retaining element / screw 5 wipers 6 axial extension gap 7 f radial extension gap 8 spaces 9 Partition wall 10 Boundary edge 12 more waves 13 Retention element 14 Spiral-shaped retaining element of 12 15 wipers out of 12 19 Partition wall / side partition wall 21 First Channel 23 Reservoir feed 25 Reservoir 27 Upstream side 31 Second channel / additional channel 33 Reservoir discharge 35 Good material reservoir 37 Outflow side 39 Axial partition of 35 40 Free distance axial partition to retaining element 100 arrangement with an HC pulper 110 HC Pulper 120 Resolution section 130 feed 150 sieve section 140 drive 170 separators 175 Lock for debris removal 180 Smaller flexible contaminants QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 24079177 A1

[0002] CN 111235934A

[0003]

Claims

[1] Sieve device (1) with at least one retention element (3, 4, 13, 14) for cleaning a suspension of contaminants, characterized by , that the sieve device (1) comprises a shaft (2, 12) which can be driven rotatorily by a drive, wherein at least one retaining element (3, 13, 4, 14) extends radially from the shaft (2, 12), wherein flowable spaces (8) are formed by the at least one retaining element (3, 13, 4, 14) and a sieving effect is provided by the flowable spaces (8). [2] Sieve arrangement (1) according to claim 1, characterized by , that the spaces (8) are perpendicular to the wave (2,12) and can be traversed. [3] Sieve device (1) according to claim 1 or 2, characterized by , that the at least one retaining element (3, 4, 13, 14) is a spiral retaining element (4, 14) extending axially. [4] Sieve device (1) according to claim 1 or 2, characterized by, that several disk elements (3, 13) arranged axially apart on the shaft (2) are provided as retaining elements (3, 13) to form gaps (8). [5] Sieve device (1) according to any one of the preceding claims, characterized by , that the at least one retaining element (3, 4, 13, 14) has axially spaced surfaces for forming gaps (8) and each gap (8) is bounded by two axially adjacent surfaces of the retaining element (4, 14) or the retaining elements (3, 13). [6] Sieve device (1) according to any one of the preceding claims, characterized by , that the radial extent (7) of one retaining element (4, 14) or of the retaining elements (3, 13) of a shaft (2) is equal. [7] Sieve device (1) according to any one of the preceding claims, characterized by , that the axial distance (6) of the spaces (8) varies over the axial extent of the shaft (2, 12). [8] Sieve device (1) according to any one of the preceding claims, characterized by , that the axial distance (6) of the spaces (8) over the axial extent of the shaft (2, 12) is the same in each case. [9] Sieve device (1) according to any one of the preceding claims, characterized by , that each retaining element (3, 4, 13, 14) has a limiting edge (10) extending coaxially to the shaft (2) in the circumferential direction and that this limiting edge (10) is free over an angular segment of the shaft (2, 12) over the axial extent of the shaft (2), wherein the shaft (2, 12) is provided in the area with the at least one retaining element (3, 13, 4, 14). [10] Sieve device (1) according to any one of the preceding claims, characterized by , that each retaining element (3, 13, 4, 14) extends at least 360° around the shaft (2,12). [11] Sieve device (1) according to any one of the preceding claims, characterized by, that at least one scraper (5,15) is provided which interacts with the limiting edge (10) or limiting edges (10) of the at least one retaining element (3,4,13,14). [12] Sieve device (1) according to claim 11, characterized by , that the scraper (5, 15) is intended for guiding foreign matter along the at least one boundary edge (10) during rotation of the shaft (2, 12) and / or that the scraper (5, 15) is intended for cutting and deflecting foreign matter. [13] Sieve device (1) according to any one of the preceding claims, characterized by , that the sieve device (1) has at least one further shaft (12) provided with at least one retention element (13, 14) and that the at least one retention element (3, 4) of the first shaft (2) engages in the spaces (8) formed by the at least one retention element (13, 14) of the further shaft (12). [14] Sieve device (1) according to any one of the preceding claims, characterized by , that the sieve device (1) has a first shaft (2) with at least one retaining element (3,4) and that the sieve device (1) has at least one further shaft (12) with at least one further retaining element (13, 14) and that the at least one retaining element (3,4) of the first shaft extends into spaces (8) of the at least one retaining element (13, 14) of the further shaft (12). [15] Separator (170) with a sieve device (1) according to one of the preceding claims, characterized by , that the sieve device (1) has an upstream side (27) and an outstream side (37) and the upstream side (27) is connected to the outstream side (37) via the spaces (8). [16] Separator according to claim 15, characterized by, that the material reservoir (35) has both lateral partitions (9, 19) and at least one, preferably two axial partitions (39), wherein preferably a free radial distance from the axial partition (39) to the limiting edge of the retention element (3, 4, 13, 14) of at least 1 / 2 times the axial distance of the smallest minimum distance (6) is provided. [17] Method for operating a separator according to claim 15 or 16, comprising the following method steps: - Feeding suspension to the sieve device (1) on the upstream side (27) - Discharge of suspension on the outflow side (37) of the sieve device - Driving the shaft to remove contaminants deposited on the boundary edges (10).

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