Corrugated cover assembly for a vacuum rotary filter drum

Abstract

Embodiments of the present disclosure may include a corrugated cover assembly for a vacuum rotary filter drum, comprising a corrugated cover element comprising crest sections and corresponding adjacent trough sections, wherein each trough section comprises an opening5 positioned at a first lateral side of the corrugated cover assembly, and each crest section and each trough section extend at least partially in a lateral direction of the corrugated cover assembly, the corrugated cover element comprises a lateral end at a second lateral side opposite the first lateral side, wherein the lateral end extends in a longitudinal direction of the corrugated cover assembly; and a sealing end strip extending along the lateral end of the corrugated cover10 element and arranged such that the lateral end is sealed.

Description

[0001] CORRUGATED COVER ASSEMBLY FOR A VACUUM ROTARY FILTER DRUM

[0002] The present disclosure relates to the field of corrugated cover assemblies for a vacuum rotary filter drum and to such vacuum rotary filter drums.

[0003] Vacuum rotary filter drums are used to separate pulp from a liquid, such as a in a washing stage in a pulp mill. The liquid can provide different harsh conditions, including a high alkalinity or acidity. The filter drums should be able to withstand those conditions for as long as possible without the filter drums or parts thereof having to be exchanged.

[0004] The filter drums are made to rotate around a central axis, wherein a lower part of the drum rotates through a bath containing pulp. A vacuum is applied from the inside to both make the pulp stick to the drum and to dry the pulp that sits on the drum after it rotated out from the bath. A wire cloth or fabric placed on the outside of the drum surface takes along the pulp and allows filtrate to be pumped out of the pulp. The surface of the wire cloth or fabric is as smooth as possible so that the dried pulp or pulp cake formed on the outside can be released using a takeoff device comprising, for example, a blade.

[0005] The filter drums often comprise a plurality of corrugated (or undulating) outer panels or covers onto which the wire cloth or fabric is placed. These corrugated covers are mounted on top of radially outward extending ribs, which in turn form walls of compartments for guiding the filtrate being pumped from the pulp away towards a filtrate outlet. The liquid from the bath and from the pulp is pumped through the wire cloth onto the corrugated cover and enter these filtrate receiving compartments which extend longitudinally within the filter drum towards one of a plurality of central outlet pipes extending radially from the central axis and leading the pumped filtrate to a central outlet pipe that is arranged along the central axis of the filter drum.

[0006] The corrugated outer covers have holes at a first lateral side that is the lower end when the drum rotates out from the liquid. In this way, when the corrugated cover comes out of the liquid, the filtrate coming from the pulp is drained towards the filtrate outlet. The drum keeps rotating and the corrugated outer covers in turn reach the highest point, and thereafter turn towards the pulp releasing blade, which is positioned above the bath to remove the dried pulp. Once over the highest point, the other, second lateral side of the corrugated outer covers is the lower end, and it is unwanted that filtrate can move back towards the pulp to rewet it again, such as via unwanted openings within the construction of the outer drum and the corrugated covers. For this reason, typically rubber sealing strips, which extend along the length of the filter drum, are used to seal or close the second lateral end of the corrugated cover. The rubber sealing strips are held in place by specially shaped clamps, which may also at least partially hold the corrugated covers. The rubber sealing is prone to wear down due to the harsh environment, and has to be replaced regularly to avoid leakage and rewetting of pulp, which is unwanted.

[0007] It is an object, among objects, to provide an improved corrugated cover assembly.

[0008] In the present disclosure there is provided in accordance with a first aspect a corrugated cover assembly for a vacuum rotary filter drum, comprising: a corrugated cover element comprising crest sections and corresponding adjacent trough sections, wherein each trough section comprises an opening positioned at a first lateral side of the corrugated cover assembly, and each crest section and each trough section extend at least partially in a lateral direction of the corrugated wall section, the corrugated cover element comprises a lateral end at a second lateral side opposite the first lateral side, wherein the lateral end extends in a longitudinal direction of the corrugated cover assembly; and a sealing end strip extending along the lateral end of the corrugated cover element and fixedly arranged to the corrugated cover element such that the lateral end is sealed.

[0009] The sealing end strip, now being comprised in the corrugated cover assembly and sealing the lateral end of the corrugated cover element, beneficially no longer needs to be replaced at a higher frequency than the whole corrugated cover assembly. It can furthermore be made of any material, such as the same material as the corrugated cover element (e.g. stainless steel), which is generally chosen to withstand the aggressive chemicals present in the bath and filtrate, and thus has a much longer lifetime. In addition, because the sealing end strip is fixedly arranged to the corrugated cover element, the installation of the corrugated cover assembly on the drum is simplified. It is possible to install the presently claimed configuration with one part, e.g. a clamp. The prior art rubber strip, to the contrary, required three or more clamp parts to attach the corrugated cover elements to the ribs of the rotary filter drum.

[0010] As will be understood, the above-described corrugated cover assembly may, in other words, comprise the sealing end strip abutting the lateral end of the corrugated cover element.

[0011] Beneficially, the sealing end strip being fixed to the corrugated cover element results in a corrugated cover assembly that is more easily replaced than previous solutions in which several separate parts would have to be properly positioned on the vacuum rotary filter drum and relative to each other. This reduces the downtime of the vacuum rotary filter drums during such maintenance. It will be understood that the sealing end strip performs a sealing function. There can, however, be some leakage of water, which is negligible relative to the amount of water that is coming from the drying pulp picked up from the bath on the outside of the drum.

[0012] The sealing end strip may be a sealing end plate. The sealing end plate may be made of a metal, such as stainless steel. The sealing end plate and the corrugated cover element may be made of the same material, and thus the lifetime of the sealing end plate is similar to that of the corrugated cover element.

[0013] In an embodiment, the sealing end strip is arranged such that each space defined by two adjacent crests and a corresponding trough between the two adjacent crests is closed. In this way, the outside of the corrugated cover element, at which side the wet pulp to be dried resides, is closed at the second lateral side thereof, thus blocking the filtrate to be able to flow back towards the pulp once the drum has rotated.

[0014] In an embodiment, the sealing end strip is arranged such that each space defined by two adjacent troughs and a corresponding crest lying between the two adjacent troughs is closed.

[0015] In an embodiment, the sealing end strip comprises a first lateral edge and a second lateral edge opposite the first lateral edge, wherein the first lateral edge of the sealing end strip is substantially aligned with each crest of the crest sections.

[0016] In an embodiment, the sealing end strip has an L-shape when seen in a lateral cross section and extends partially along each trough of the trough sections. In an embodiment, the sealing end strip is fixed to the corrugated cover element at several of the troughs, preferably at each Nth trough, N being a natural number equal to or higher than 1, more preferably at all the troughs. The strip is fixed at the inside of the corrugated cover element, inside referring to the inside of the filter drum, that is, when the corrugated cover assembly is mounted on the filter drum.

[0017] In an embodiment, the sealing end strip is fixed to the corrugated cover element at the troughs by spot welds. Spot welding is beneficial since it creates a durable bond, while the welds can be done at the troughs there is no need for filling up the space between the strip and the remainder of the surface of the sealing end strip which does not contact either the lateral end of the corrugated cover element or the inside of the troughs near the lateral end.

[0018] In an embodiment, the corrugated cover element comprises a first assembly portion at the first lateral side and a second assembly portion at the second lateral side, wherein the second assembly portion comprises the lateral end along which the sealing end strip extends. These assembly portion allow for working together with mounting members, such as clamps, to mount the corrugated cover assembly to be mounted on the filter drum.

[0019] In an embodiment, the corrugated cover element has a thickness defined by the crests and troughs, wherein the first assembly portion and the second assembly portion each have a reduced thickness compared to a remainder of the corrugated cover element. With the reduced thickness, there is space for the holding member, such as a bracket member, e.g. a clamp, to hold the corrugated cover assembly such that the outside of the drum can remain relatively smooth, helping in the effective removal of the dried pulp.

[0020] In an embodiment, crests within the first assembly portion and the second assembly portion are offset in a thickness direction of the corrugated cover element relative to crest sections of the remainder of the corrugated cover element, and wherein troughs in the first and second assembly portions substantially align with troughs in the remainder of the corrugated cover element. In this way, a particularly smooth outside of the rotating drum is achieved, such that the wire cloth can be put around the drum in a similarly smooth fashion. In this way, an even more effective or efficient removal of the dried pulp is achieved. Substantially align may indicate with an acceptable maximum misalignment according to engineering standards. A maximum misalignment may be, for example, 1 mm, preferably 0.5 mm.

[0021] In an embodiment, the first assembly portion and / or second assembly portion is configured to work together with a bracket member, wherein the bracket member is configured to be fixed to the vacuum rotary filter drum and to hold the first assembly portion onto the vacuum rotary filter drum. One backet member may further be configured to additionally hold the second assembly portion of another corrugated cover assembly. The bracket member can be placed with a middle section on an outer radial end of a mounting rib of the filter drum.

[0022] The corrugated cover assembly can be mounted by first placing the first end in one bracket member that may be fixed to an outer radial end of the filter drum. The middle section of the corrugated cover assembly, seen in the lateral direction, between the first and the second lateral sides, is supported by one or more supporting ribs of the filter drum that radially extend outward. The corrugated cover assembly, by leaning on the supporting ribs with its middle section, may be bent such that, when mounted in two respective bracket members, the first and second assembly portions are pushing radially outwards against the bracket members. In this way, the corrugated cover assembly is held in place. In an embodiment, the bracket member comprises a C-shape when seen in a lateral cross section.

[0023] In an embodiment, the bracket member comprises an additional C-shape when seen in a lateral cross section, the additional C being arranged back-to-back with the C-shape, and wherein the bracket member comprises a connecting part for connecting the C-shapes wherein the connecting part is configured to be welded to a radial end of a mounting rib of the filter drum.

[0024] In an embodiment, the corrugated cover element is a corrugated cover plate.

[0025] In an embodiment, the corrugated cover element is curved in the lateral direction, wherein the lateral direction is perpendicular to the longitudinal direction. The curvature is such that it matches the curvature of the rotary filter drum it is to be fitted on.

[0026] In an embodiment, the corrugated cover element has a rectangular shape when viewed perpendicular to both the lateral direction and the longitudinal direction.

[0027] In accordance with a second aspect, there is provided a kit of parts, comprising the corrugated cover assembly according to any embodiment described above and below, and at least one bracket member configured to hold the corrugated cover assembly and to be fixed to the vacuum rotary filter drum.

[0028] In accordance with a third aspect, there is provided a vacuum rotary filter drum, comprising at least one corrugated cover assembly according to any embodiment described above and below.

[0029] In an embodiment, the vacuum rotary filter drum comprises a plurality of corrugated filter wall receiving sections, each corrugated filter receiving section being configured to receive one corrugated cover assembly, wherein each corrugated filter receiving section comprises a plurality of supporting ribs for supporting the corrugated cover assembly, each rib extending longitudinally along the vacuum rotary filter drum and extending radially outwards towards an outer circumference of the vacuum rotary filter drum, wherein two adjacent ribs of the plurality of supporting ribs define sides of a respective filtrate receiving compartment extending longitudinally towards a central fluid outlet configured to be pumped with a vacuum pump.

[0030] It will be understood that technical advantages and effects associated with features and / or embodiments of one aspect, apply to the corresponding, similar or equivalent features and / or embodiments the other aspects. It will also be apparent that the features of the various aspects and / or embodiments thereof may be applied to the other aspects and / or embodiments thereof. Further aspects and / or embodiments may follow from the following description of the drawings.

[0031] Brief Description of the Drawings

[0032] The accompanying drawings are used to illustrate presently preferred non-limiting exemplary embodiments of devices of the present disclosure. The above and other advantages of the features and objects of the disclosure will become more apparent, and the aspects and embodiments will be better understood from the following detailed description when read in conjunction with the accompanying drawings, in which:

[0033] FIG. 1 is a schematic view of a cross-section along a central axis of a vacuum rotary filter drum according to some embodiments of the present disclosure;

[0034] FIG. 2 is a schematic view of a lateral cross-section as indicated in FIG. 1 of the vacuum rotary filter drum, according to some embodiments of the present disclosure;

[0035] FIG. 3 is a schematic orthographic view of an outer section of a vacuum rotary filter drum according to some embodiments of the present disclosure;

[0036] FIG. 4 is a schematic orthographic view of a corrugated cover assembly according to some embodiments of the present disclosure;

[0037] FIG. 5 is a schematic side view of a lateral side of a corrugated cover assembly according to some embodiments of the present disclosure;

[0038] FIG. 6 is a schematic view of a cross section along the lateral direction of the corrugated cover assembly according to some embodiments of the present disclosure;

[0039] FIG: 7 is a schematic view of a detail of the cross section of FIG. 6;

[0040] FIG. 8 is a schematic view of a cross section along the lateral direction of the corrugated cover assembly of FIG. 6 mounted in a rotary filter drum; and

[0041] FIG: 9 is a schematic view of a cross section of the corrugated cover assembly according to some embodiments of the present disclosure.

[0042] Detailed Description of Preferred Embodiments

[0043] FIG. 1 shows an example of a vacuum rotary filter drum 1 according to the present patent disclosure. The filter drum 1 comprises a plurality of corrugated cover assemblies 10, each arranged along a segment of the outer circumference of the filter drum 1. The filter drum 1 is typically placed within a housing, which may include further parts, such as washing pipes for washing pulp. The filter drum 1 further comprises one or more respective filtrate receiving compartments 5 associated with each corrugated cover assembly 10. In this example, the filtrate receiving compartments 5 extend longitudinally towards a central fluid outlet 106 among a plurality of central fluid outlets and configured to be pumped with a vacuum pump (not shown). The central fluid outlets 106 may extend radially from a centre filtrate pipe 106, which may be connected to the vacuum pump, in this example via a 90 degree corner tube 110. The central fluid outlets 106 may extend radially from hub 109, which connects the central fluid outlets 106 to the central filtrate pipe 106. The central filtrate pipe 106 is arranged to extend longitudinally through the filter drum 1 from a first longitudinal end 114 of the filter drum 1 towards the hub 109 along central axis 108. The corrugated cover assemblies 10 extend longitudinally parallel to the central axis, and are supported by the central fluid outlets 106 in the middle of the filter drum 1, and by two supporting wheels 112 located at a respectively the first longitudinal end 114 and second longitudinal end 116 of the filter drum 1.

[0044] FIG. 2 shows a schematic and simplified cross-section view of the filter drum 1 along the central axis 108. The filter drum 1, having a certain size, is here fitted with 40 corrugated cover assemblies 10. For each corrugated cover section 10, the filter drum 1 may comprise a respective central fluid outlet 106. In this example, the filter drum 1 comprises three filtrate receiving compartments 5 for each corrugated cover section 10.

[0045] Inside the hub 109 may be arranged a closing valve 120 that is arranged at a fixed angle such that it closes an angular range 134 along which the central fluid outlets 106 rotate, so that no vacuum is applied to the central fluid outlets 106 that are in the angular range 134, where the take-off device 154 takes the pulp from the outer circumference of the filter drum 1 and feeds it to the pulp screw 140. Vacuum is applied in the vacuum angular range 130. The filter drum 1 is arranged in a bath comprising pulp in an aqueous solution. The bath fed by inlet 150. The fluid with pulp has fluid level 190, which is preferably kept at constant. Angular ranges 132 and 136 indicate positions of the central fluid outlets 106 where the vacuum is partially applied. The valve 120 is fixedly connected to an axle (not shown) which extends along the central axis, around which the further rotating parts of the filter drum 1 are rotatably arranged.

[0046] The filter drum 1 in this example further comprises a plurality of corrugated filter wall receiving sections 3, each corrugated filter receiving section being configured to receive one corrugated cover assembly 10, wherein each corrugated filter receiving section 3 comprises a plurality of supporting ribs 30 (FIG. 3) for supporting the corrugated cover assembly 10, which comprises the corrugated cover element 56. Each rib 30 extends longitudinally along the vacuum rotary filter drum 1 and extends radially outwards towards the outer circumference of the vacuum rotary filter drum 1. The plurality of imperforate upstanding rib or division elements 30 are rigidly mounted on an outer circumference 20 of the drum circumferentially spaced around the drum to cause circumferentially adjacent ones of the elements 30 of each drum to form opposing side walls of circumferential filtrate compartments 5. The rib elements 30 extend generally longitudinally along the outer drum circumferences 20 substantially throughout the length of their respective drum; thus, the filtrate compartments 5 of each drum extend generally longitudinally along the outer circumference 20 of the latter substantially throughout its extent.

[0047] As illustrated, a supporting rib element 34 is affixed to each outer circumference 20 intermediate each two or more circumferentially adjacent rib elements 30. The supporting rib elements 34 extend generally longitudinally along the outer circumferences 20 and have openings 36 there through communicating the portions of the filtrate compartments 5 on opposite sides thereof. Alternatively, however, more than one, preferably two, supporting rib element 34 may be provided between each two of the circumferentially adjacent ones of the rib elements 30.

[0048] The drum structure 10 also includes a corrugated cover assembly 10 mounted circumferentially over the filtrate compartments 5 of each drum. In this example, the corrugated cover of the drum is formed by a plurality of separate corrugated cover elements or plates 56, each longitudinally the length of one of the filtrate compartments 5 and transversely or circumferentially a width slightly less than one of the filtrate compartments 5, which are mounted along opposite side edges to circumferentially adjacent ones of the rib elements 30. The corrugated cover plates 56 each include an inner face or surface bounding the circumferentially outer side of a respective filtrate compartment 5 and an outer face or surface facing away from such filtrate compartment 5; and the circumferentially adjacent ones of the cover elements 56 of each drum are circumferentially spaced one from the other by the rib element 30 and sometimes also the mounting member 70, depending on its shape. The inner face of each cover element 56 is supported on, but preferably not rigidly affixed to, the intermediate rib 34 in the filtrate compartment.

[0049] The corrugations of the cover elements 56 preferably extend circumferentially of the drum to provide the inner face of each cover element 56 with substantially parallel, alternate, transverse ridges (or crests) and grooves (or troughs) while providing the outer face of each cover element 56 with similar generally parallel, alternate, transverse ridges and grooves. The grooves and ridges extend the full width of the cover elements 56. Corrugations easily accommodate thermal expansion, which is a feature inherent in the design. The formation of the corrugations transversely of the cover elements 56 provides the cover elements 56 with substantial inherent flexibility, which is beneficial in case of thermal changes in the longitudinal direction of the drum.

[0050] As illustrated in FIG. 2, the cover elements 56 are supported in their positions overlaying the filtrate compartments 5 on the rib elements 30 by a mounting member 70, in FIG. 3 shown schematically as a mounting clip with recess 72 mounted on each of the rib elements 30. The mounting members 70 according to the present patent disclosure may have a different shape, as will be described further below.

[0051] Each groove in each cover element 56 is provided with an opening 58 communicating the groove with the there below filtrate compartment 5 for draining liquid from the former to the latter. The openings 58, as best shown in FIG. 4, are at the bottoms of the grooves or troughs 16. Although only a single louvered opening 58 located adjacent the edge of the cover element 56 is shown in communication with each groove in the illustrated embodiment, it will be understood that, if desired or required, additional openings 58 could be provided for each of the troughs 16.

[0052] The usual wire filter medium 92 is affixed around each drum and supported on the peaks of the ridges of the outer surface of the cover elements 56 and the mounting members 70.

[0053] In the operation of the filtering apparatus, the drum structure 10 is rotatably driven in the clockwise direction (as viewed in FIG. 2) to successively drive the filtrate compartments 5 below the level 190 of the slurry in for solid material accretion on the filter medium 92 and then above such level for drying of accumulated solid material and removal of such material by the take-off device 154. During the initial submergence of the filtrate compartments 5 into the slurry, solid material accretion is effected without the assistance of the sub-atmospheric pressure, but air in the initially submerging filtrate compartments 5 is allowed to escape to the atmosphere. Then, sub-atmospheric pressure is applied to the filtrate compartments 5 through their open ends and additional solid material is resultantly collected on the filter medium 92. The sub-atmospheric pressure continues to be applied to the compartments 5 as the latter are rotated above the level of the slurry and the accumulated solid material is being dried. The sub- atmospheric pressure is cut-off from the filtrate compartments 5 as they are rotated further, where the dried collected solid material is removed from the filter medium 92 preparatory to the commencement of another filter cycle.

[0054] The liquid drained through the openings 58 in the filter medium 92 passes into the grooves in outer surfaces of the cover elements 56 and flows in such grooves circumferentially of the drum structure 10 to the openings 58 which discharge the liquid to the there below filtrate compartments 5.

[0055] The corrugated cover assembly 10 is shown in more detail in FIG. 4. The corrugated cover element comprises crest sections 14 and corresponding adjacent trough sections 16. Each trough section 16 comprises, in this example, one of the openings 58. Each opening is positioned at a first lateral side 22 of the corrugated cover assembly. The corrugations may be described in terms of pitch, being the distance between two crests (or two troughs), and depth, being the height from the top of a crest to the bottom of a trough.

[0056] Each crest section 14 and each trough section 16 extend at least partially in a lateral direction of the corrugated cover assembly 10. The corrugated cover element 56 comprises a lateral end 26 at a second lateral side 24 opposite the first lateral side 22. The lateral end 26 extends in a longitudinal direction 104 of the corrugated cover assembly 10. The corrugated cover assembly further comprises a sealing end strip 40 extending along the lateral end 26 of the corrugated cover element 56 and arranged such that the lateral end 10 is sealed. Only a part of the sealing end strip 40 is shown FIG. 4 for indicatory purposes. The sealing end strip 40 extends along the entire lateral end 26 in order to seal it.

[0057] The sealing end strip 40 is arranged such that each first space 47 defined by two adjacent crests 14 and a corresponding trough 16 between the two adjacent crests 14 is closed or sealed. This first space 47 is indicated schematically in FIG. 5. The sealing end strip may also be arranged such that each second space 48 defined by two adjacent troughs 16 and a corresponding crest 14 lying between the two adjacent troughs 16 is closed or sealed.

[0058] As visible in FIG. 6 and enlarged in FIG. 7, the sealing end strip 40 comprises a first lateral edge 42 and a second lateral edge 44 opposite the first lateral edge 42. The first lateral edge 42 of the sealing end strip 40 is substantially aligned with the crest 14’ in FIG. 7. In an embodiment, as shown in Fig. 10, the first lateral edge 420 is slanted or chamfered, thus forming a slanted or chamfered lateral edge 420. The first lateral edge 420 also in this case aligns with the crest 14’ of the corrugated cover element 56. The use of a chamfered lateral edge may avoid damage during assembly and reduces stress at the lateral edge side of the sealing end strip 40, improving durability and longevity of the entire assembly.

[0059] The sealing end strip 40 has an L-shape (in the view of FIG. 6 a mirrored or rotated L) when seen in a lateral cross section. The sealing end strip 40 comprises an overlap section 41 which extends partially along each trough of the trough sections 16. The overlap section 41 comprises the second lateral edge 44 and is connected to the lateral end section 45, which comprises the first lateral edge 42, via the corner section 43. The sealing end strip 40 may be fixed to the corrugated cover element 56 at several of the troughs, preferably at each Nth trough, N being a natural number equal to or higher than 1, more preferably at all the troughs. The sealing end strip 40 may be fixed to the corrugated cover element 56 at the troughs by spot welds.

[0060] The corrugated cover element 56 comprises a first assembly portion 62 at the first lateral side 22 and a second assembly portion 64 at the second lateral side 24, wherein the second assembly portion 64 comprises the lateral end 26 along which the sealing end strip 40 extends.

[0061] The corrugated cover element 56 has a thickness 59 defined by the crests and troughs. The first assembly portion 62 and the second assembly portion 64 in this example each have a reduced thickness 59’ compared to a remainder of the corrugated cover element 56.

[0062] The crests 14’ within the first assembly portion 62 and the second assembly portion 64 are offset in a thickness direction 58 of the corrugated cover element 56 relative to crest sections 14 of the remainder of the corrugated cover element 56. Troughs in the first 62 and second 64 assembly portions preferably substantially align with troughs in the remainder of the corrugated cover element 56.

[0063] The first assembly portion 62 and / or second assembly portion 64 is / are configured to work together with a bracket member 70, as can be seen in FIG. 8. The bracket member 70 is configured to be fixed to the vacuum rotary filter drum 1 and to hold the first assembly portion 62 onto the vacuum rotary filter drum 1. In the embodiment of FIG. 8, the bracket member 70 has a C-shape when seen in a lateral cross section. The bracket member 70 may further be configured to additionally hold the second assembly portion of another, adjacent, corrugated cover assembly. The bracket member 70 is then placed with a connecting section on an outer radial end of a mounting rib 30 of the filter drum 1. The connecting section may comprise holes to allow for efficient spot welding of the bracket members to the outer radial ends of the ribs 30.

[0064] The corrugated cover assembly 10 may be mounted by first placing the first end in one bracket member 70 that may be fixed to an outer radial end of the rib 30 of the filter drum. The middle section of the corrugated cover assembly, seen in the lateral direction, between the first and the second lateral sides, is, in FIG. 8, supported by two supporting ribs 31 of the filter drum that radially extend outward. The corrugated cover assembly 10, by leaning on the supporting ribs 31 with its middle section, may be bent slightly such that, when mounted in two respective bracket members, the first and second assembly portions are pushing radially outwards against the bracket members. In this way, the corrugated cover assembly is held in place. After the second assembly portion 64 is in place, the bracket member 70 holding the second assembly portion 64 may be fixed to the respective rib 30.

[0065] In the example of FIG. 8, the bracket member comprises an additional C-shape when seen in a lateral cross section, the additional C being arranged back-to-back with the C-shape, and wherein the bracket member comprises the connecting section connecting the C-shapes wherein the connecting section is configured to be welded to a radial end of a mounting rib of the filter drum.

[0066] The function of the corrugated filter assembly 10 together with the filter drum 1 is as follows. Starting in the bath comprising pulp, from the viewpoint of one of the corrugated filter assemblies 10, this assembly 10 rotates clockwise in the drum 1 of FIG. 2 as indicated by the rotation direction R, and, vacuum being applied to the respective central fluid pipe 106 and thus the respective filtrate receiving compartments 5 associated with the one assembly 10, pulp is sucked onto the wire filter medium 92. Rotating further, the one corrugated filter assembly 10 moves out of the bath, while the remaining water moves down towards the first lateral side 22 of the corrugated filter assembly, into the compartments 5 and further to the respective central fluid pipe 106. Rotating further, the one corrugated filter assembly 10 moves to and across the maximum height of the filter drum, and thus the second lateral side 24 becomes the lowest side. As may be understood best from FIG. 8, in which the rotation direction is indicated, the water may then move towards the right in FIG. 8, and when rotated sufficiently, the water may come into contact with the corrugated filter plate 58, but can’t reach the pulp on the outside of the corrugated filter plate 58 because of the sealing end strip 40 closing the lateral end 26 of the corrugated filter plate 58. In other words, the water or filtrate is blocked from flowing back to the pulp.

[0067] The disclosure further comprises the following examples:

[0068] Example 1. Corrugated cover assembly for a vacuum rotary filter drum, comprising: a corrugated cover element comprising crest sections and corresponding adjacent trough sections, wherein each trough section comprises an opening positioned at a first lateral side of the corrugated cover assembly, and each crest section and each trough section extend at least partially in a lateral direction of the corrugated cover assembly, the corrugated cover element comprises a lateral end at a second lateral side opposite the first lateral side, wherein the lateral end extends in a longitudinal direction of the corrugated cover assembly; and a sealing end strip extending along the lateral end of the corrugated cover element and arranged such that the lateral end is sealed.

[0069] Example 2. Corrugated cover assembly according to example 1, wherein the sealing end strip (40) is arranged such that each space defined by two adjacent crests and a corresponding trough between the two adjacent crests is closed.

[0070] Example 3. Corrugated cover assembly according to example 2, wherein the sealing end strip is arranged such that each space defined by two adjacent troughs and a corresponding crest lying between the two adjacent troughs is closed.

[0071] Example 4. Corrugated cover assembly according to any one of the preceding examples, wherein the sealing end strip is made of a metallic material, preferably stainless steel.

[0072] Example 5. Corrugated cover assembly according to any one of the preceding examples, wherein the sealing end strip comprises a first lateral edge and a second lateral edge opposite the first lateral edge, wherein the first lateral edge of the sealing end strip is substantially aligned with each crest of the crest sections.

[0073] Example 6. Corrugated cover assembly according to any one of the preceding examples, wherein the sealing end strip has an L-shape when seen in a lateral cross section and extends partially along each trough of the trough sections, wherein the sealing end strip is fixed to the corrugated cover element at several of the troughs, preferably at each Nth trough, N being a natural number equal to or higher than 1, more preferably at all the troughs.

[0074] Example 7. Corrugated cover assembly according to example 6, wherein the sealing end strip is fixed to the corrugated cover element at the troughs by spot welds.

[0075] Example 8. Corrugated cover assembly according to any one of the preceding examples, wherein the corrugated cover element comprises a first assembly portion at the first lateral side and a second assembly portion at the second lateral side, wherein the second assembly portion comprises the lateral end along which the sealing end strip extends. Example 9. Corrugated cover assembly according to example 8, wherein the corrugated cover element has a thickness defined by the crests and troughs, wherein the first assembly portion and the second assembly portion each have a reduced thickness compared to a remainder of the corrugated cover element.

[0076] Example 10. Corrugated cover assembly according to example 9, wherein crests within the first assembly portion and the second assembly portion are offset in a thickness direction of the corrugated cover element relative to crest sections of the remainder of the corrugated cover element, and wherein troughs in the first and second assembly portions substantially align with troughs in the remainder of the corrugated cover element.

[0077] Example 11. Corrugated cover assembly according to example 8, 9 or 10, wherein the first assembly portion and / or second assembly portion is configured to work together with a bracket member, wherein the bracket member is configured to be fixed to the vacuum rotary filter drum and to hold the first assembly portion onto the vacuum rotary filter drum.

[0078] Example 12. Corrugated cover assembly according to example 2, wherein the bracket member has a C-shape when seen in a lateral cross section.

[0079] Example 13. Corrugated cover assembly according to any one of the preceding examples, wherein the corrugated cover element is a corrugated cover plate.

[0080] Example 14. Corrugated cover assembly according to any one of the preceding examples, wherein the corrugated cover element is curved in the lateral direction, wherein the lateral direction is perpendicular to the longitudinal direction; and / or wherein the corrugated cover element has a rectangular shape when viewed perpendicular to both the lateral direction and the longitudinal direction.

[0081] Example 15. Kit of parts, comprising the corrugated cover assembly according to any one of examples 1 to 14, and at least one bracket member configured to hold the corrugated cover assembly and to be fixed to the vacuum rotary filter drum.

[0082] Example 16. Vacuum rotary filter drum, comprising at least one corrugated cover assembly according to any one of examples 1 to 14.

[0083] Example 17. Vacuum rotary filter drum, comprising a plurality of corrugated filter wall receiving sections, each corrugated filter receiving section being configured to receive one corrugated cover assembly, wherein each corrugated filter receiving section comprises a plurality of supporting ribs for supporting the corrugated cover assembly, each rib extending longitudinally along the vacuum rotary filter drum and extending radially outwards towards an outer circumference of the vacuum rotary filter drum, wherein two adjacent ribs of the plurality of supporting ribs define sides of a respective filtrate receiving compartment extending longitudinally towards a central fluid outlet configured to be pumped with a vacuum pump.

[0084] Although the present invention has been described with reference to specific embodiments, also shown in the appended drawings, it will be apparent to those skilled in the art that many variations and modifications can be done within the scope of the invention as described in the specification and defined with reference to the claims below.

Claims

CLAIMS1. Corrugated cover assembly (10) for a vacuum rotary filter drum (1), comprising: a corrugated cover element (56) comprising crest sections (14) and corresponding adjacent trough sections (16), wherein each trough section (16) comprises an opening (58) positioned at a first lateral side (22) of the corrugated cover assembly (10), and each crest section (14) and each trough section (16) extend at least partially in a lateral direction of the corrugated cover assembly (10), the corrugated cover element (56) comprises a lateral end (26) at a second lateral side (24) opposite the first lateral side (22), wherein the lateral end (26) extends in a longitudinal direction (104) of the corrugated cover assembly (10); and a sealing end strip (40) extending along the lateral end (26) of the corrugated cover element (56) and fixed to the corrugated cover element such that the lateral end (26) is sealed, wherein the corrugated cover element (56) is made of a metallic material, and the sealing end strip (40) has an L- shape when seen in a lateral cross section and extends partially along each trough of the trough sections (16), wherein the sealing end strip (40) is fixed to the corrugated cover element (56) at several of the troughs.

2. Corrugated cover assembly (10) according to claim 1, wherein the sealing end strip (40) is arranged such that each space (47) defined by two adjacent crests and a corresponding trough between the two adjacent crests is closed.

3. Corrugated cover assembly (10) according to claim 2, wherein the sealing end strip (40) is arranged such that each space (48) defined by two adjacent troughs and a corresponding crest lying between the two adjacent troughs is closed.

4. Corrugated cover assembly (10) according to any one of the preceding claims, wherein the sealing end strip (40) is made of stainless steel, and / or the corrugated cover element (56) is made of a metallic material, preferably stainless steel, more preferably the same material as the sealing end strip (40).

5. Corrugated cover assembly (10) according to any one of the preceding claims, wherein the sealing end strip (40) comprises a first lateral edge (42, 420) and a second lateral edge (44) opposite the first lateral edge (42, 420), wherein the first lateral edge (42, 420) of the sealingend strip (40) is substantially aligned with each crest of the crest sections (14), wherein optionally the first lateral edge (420) is at least partially chamfered.

6. Corrugated cover assembly (10) according to any one of the preceding claims, wherein the sealing end strip (40) is fixed to the corrugated cover element (56) at each Nth trough, N being a natural number equal to or higher than 1, more preferably at all the troughs.

7. Corrugated cover assembly (10) according to claim 6, wherein the sealing end strip (40) is fixed to the corrugated cover element (56) at the troughs by spot welds.

8. Corrugated cover assembly (10) according to any one of the preceding claims, wherein the corrugated cover element (56) comprises a first assembly portion (62) at the first lateral side (22) and a second assembly portion (64) at the second lateral side (24), wherein the second assembly portion (64) comprises the lateral end (26) along which the sealing end strip (40) extends.

9. Corrugated cover assembly (10) according to claim 8, wherein the corrugated cover element (56) has a thickness (59) defined by the crests and troughs, wherein the first assembly portion (62) and the second assembly portion (64) each have a reduced thickness (59’) compared to a remainder of the corrugated cover element (56).

10. Corrugated cover assembly (10) according to claim 9, wherein crests (14’) within the first assembly portion (62) and the second assembly portion (64) are offset in a thickness direction (58) of the corrugated cover element (56) relative to crest sections (14) of the remainder of the corrugated cover element (56), and wherein troughs in the first and second assembly portions substantially align with troughs in the remainder of the corrugated cover element (56).

11. Corrugated cover assembly (10) according to claim 8, 9 or 10, wherein the first assembly portion (62) and / or second assembly portion (64) is configured to work together with a bracket member (70), wherein the bracket member (70) is configured to be fixed to the vacuum rotary filter drum (1) and to hold the first assembly portion (62) onto the vacuum rotary filter drum (1).

12. Corrugated cover assembly (10) according to claim 2, wherein the bracket member (70) has a C-shape when seen in a lateral cross section.

13. Corrugated cover assembly (10) according to any one of the preceding claims, wherein the corrugated cover element (56) is a corrugated cover plate.

14. Corrugated cover assembly (10) according to any one of the preceding claims, wherein the corrugated cover element (56) is curved in the lateral direction (102), wherein the lateral direction is perpendicular to the longitudinal direction (104); and / or wherein the corrugated cover element (56) has a rectangular shape when viewed perpendicular to both the lateral direction (102) and the longitudinal direction (104).

15. Kit of parts, comprising the corrugated cover assembly (10) according to any one of claims 1 to 14, and at least one bracket member (70) configured to hold the corrugated cover assembly (10) and to be fixed to the vacuum rotary filter drum (1).

16. Vacuum rotary filter drum (1), comprising at least one corrugated cover assembly according to any one of claims 1 to 14.

17. Vacuum rotary filter drum (1) according to claim 16, comprising a plurality of corrugated filter wall receiving sections (3), each corrugated filter receiving section being configured to receive one corrugated cover assembly (10), wherein each corrugated filter receiving section (3) comprises a plurality of supporting ribs (30) for supporting the corrugated cover assembly (10), each rib extending longitudinally along the vacuum rotary filter drum (1) and extending radially outwards towards an outer circumference of the vacuum rotary filter drum (1), wherein two adjacent ribs of the plurality of supporting ribs define sides of a respective filtrate receiving compartment (5) extending longitudinally towards a central fluid outlet configured to be pumped with a vacuum pump.

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