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EP-4414500-B1 - REFINING SEGMENT

EP4414500B1EP 4414500 B1EP4414500 B1EP 4414500B1EP-4414500-B1

Inventors

  • RUOLA, VILLE

Dates

Publication Date
20260513
Application Date
20240201

Claims (12)

  1. A refining segment (4) for a refiner (1) for refining lignocellulose-containing fibrous material, the refining segment (4) comprising an inner end edge (20) and an outer end edge (21) opposite to the inner end edge (20), and a refining surface (5) comprising refining bars (25) and refining grooves (26) therebetween, wherein the refining surface (5) of the refining segment (4) comprises at least one recess (27, 27', 27") extending from the outer end edge (21) of the refining segment (4) at least partly towards the inner end edge (20) of the refining segment (4) for forming at least partly at least one backflow guide groove (28) extending from the outer end edge (21) of the refining segment (4) at least partly towards the inner end edge (20) of the refining segment (4), and wherein a volume of the at least one recess (27, 27', 27") is arranged to decrease towards the inner end edge (20) of the refining segment (4) for providing the volume of the at least one backflow guide groove (28) to decrease towards the inner end edge (20) of the refining segment (4), characterized in that a depth of the at least one recess (27, 27', 27") is arranged to decrease towards the inner end edge (20) of the refining segment (4) for decreasing the volume of the backflow guide groove (28) towards the inner end edge (20) of the refining segment (4).
  2. A refining segment as claimed in claim 1, characterized in that at least one recess (27, 27', 27") is arranged to extend from the outer end edge (21) of the refining segment (4) at least partly towards the inner end edge (20) of the refining segment (4) without extending up to the inner end edge (20) of the refining segment (4) for forming at least one backflow guide groove (28) that extends from the outer end edge (21) of the refining segment (4) at least partly towards the inner end edge (20) of the refining segment (4) without extending up to the inner end edge (20) of the refining segment (4).
  3. A refining segment as claimed in claim 1 or 2, characterized in that a width of the recess (27, 27', 27") is arranged to decrease towards the inner end edge (20) of the refining segment (4) for decreasing the volume of the backflow guide groove (28) towards the inner end edge (20) of the refining segment (4).
  4. A refining segment as claimed in claim 3, characterized in that the backflow guide groove (28) has a first end (28a) at the outer end edge (21) of the refining segment (4) and a second end (28b) facing at least partly towards the inner end edge (20) of the refining segment (4), and that a width (W28b) of the second end (28b) of the backflow guide groove (28) is about 0-95% of a width (W28a) of the first end (28a) of the backflow guide groove (28).
  5. A refining segment as claimed in claim 3 or 4, character- ized in that the width (W28a) of the first end (28a) of the backflow guide groove (28) is about 5-20mm.
  6. A refining segment as claimed in any one of the preceding claims, characterized in that the backflow guide groove (28) has a first end (28a) at the outer end edge (21) of the refining segment (4) and a second end (28b) facing at least partly towards the inner end edge (20) of the refining segment (4), and that a bottom (28c) of the backflow guide groove (28) is arranged to ascend from the first end (28a) of the backflow guide groove (28) towards the second end (28b) of the backflow guide groove (28b) at an angle (α) of about 0.1-5 degrees for decreasing the volume of the backflow guide groove (28) towards the inner end edge (20) of the refining segment (4).
  7. A refining segment as claimed in claim 6, characterized in that the depth (D28) of the backflow guide groove (28) at the first end (28a) thereof is about 3-10mm below a bottom of the refining grooves (26).
  8. A refining segment as claimed in any one of the preceding claims, characterized in that the backflow guide groove (28) is arranged to extend from the outer end edge (21) of the refining segment (4) to a distance of 25% to 75% of a length of the refining segment (4) between the outer end edge (21) of the refining segment (4) and the inner end edge (20) of the refining segment (4).
  9. A refining segment as claimed in any one of the preceding claims, characterized in that the backflow guide groove (28) is substantially straight and arranged to extend in a substantially straight direction from the outer end edge (21) of the refining segment (4) towards the inner end edge (20) of the refining segment (4).
  10. A refining segment as claimed in any one of claims 1 to 8, char- acterized in that the backflow guide groove (28) is curved and arranged to extend in a curved manner from the outer end edge (21) of the refining segment (4) towards the inner end edge (20) of the refining segment (4).
  11. A refining segment as claimed in any one of the preceding claims, characterized in that the refining surface (5) of the refining segment (4) comprises holes (29a, 29b, 29c) extending through a blade segment body (4c).
  12. A refining segment as claimed in claim 11, characterized in that the holes (29a, 29b, 29c) are arranged in line with the at least one backflow guide groove (28).

Description

FIELD OF THE INVENTION The invention relates to the refining of fibrous material and especially to a refining segment for a refiner for refining lignocellulose-containing fibrous material. BACKGROUND OF THE INVENTION Refiners used for refining fibrous material, such as refiners used for manufacturing mechanical pulp or in any low consistency refining, comprise typically two refining elements opposite to each other and turning relative to each other, i.e., one or both is/are rotating. The refining elements comprise refining surfaces provided with refining bars and refining grooves therebetween, the refining bars being intended to defibre and refine the material to be refined, i.e., pulp, and the refining grooves being intended to convey the material to be refined forward along the refining surfaces. The refining surface of the refining element is typically formed of several refining segments fastened to a body of the respective refining element, whereby the refining segments comprise refining surfaces provided with the refining bars and the refining grooves therebetween. In that case the complete refining surface of the refining element is thus formed of the refining surfaces of said several refining segments fastened next to each other in the refining element. An example of a refining segment like that is shown in FI-publication 126263 B, wherein the refining segment comprises a refining surface provided with refining bars and refining grooves therebetween and with specific feeding grooves extending from an inner end edge of the refining segment towards an outer end edge of the refining segment and intended to convey the material to be refined and the material already refined towards the outer edge of the refining segment, and thereby to increase a capacity of the refining. Alternatively, the refining segment may be a single uniform piece extending over a whole circumference of the respective refining element, whereby refining bars and refining grooves in a refining surface of this single uniform piece form the complete refining surface of the refining element. The refining segments of this type are also called refiner fillings. Another example of a refining segment is disclosed in US 2007/0164143 A1. All processes for manufacturing pulp from lignocellulosic material produce shives as an undesired quality problem. A shive is a particle or fibre bundle or wood fragment that is produced by incomplete splitting of wood material into fibres during cooking or mechanical treatment. The shives not only contaminate the quality of the produced pulp but also deteriorate operation of some processing devices such as refiners, wherein the shives have a tendency of blocking the refining surfaces and thereby degrading quality of the produce pulp and decreasing a capacity of the refiner. Therefore, there is a need for reducing an amount or a proportion of shives in the pulp. BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to provide a novel refining segment for refining fibrous material. The invention is characterized by the features of the independent claim. The invention is based on the idea of improving refining effect to be subjected to the fibrous material to be refined by collecting fibrous material, and shives therein, flowing backwards on the refining surface of the refining segment, and guiding the backward flowing fibrous material and shives therein in a controlled manner back into a refining gap in a refiner in order to achieve the expected refining effect. The advantage of the invention is that the amount of the shives known as a by-product of fibre production and supposed to be removed during fibre processing will decrease without scarifying pulp properties, and in fact, other pulp quality parameters like strengths, formation and smoothness will improve when the amount of the shives in the pulp is reduced. Some embodiments of the invention are disclosed in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which Figure 1 shows schematically a partly cross-sectional side view of a conical refiner comprising conical refining elements;Figure 2 shows schematically a stator refining segment seen obliquely from above;Figure 3 shows schematically an example of a test result of a practical refining experiment;Figure 4A shows schematically from above a second stator refining segment;Figure 4B shows schematically a side view of the refining segment of Figure 4A in cross section;Figure 5A shows schematically from above a third stator refining segment;Figure 5B shows schematically a side view of the refining segment of Figure 5A in cross section;Figure 6 shows schematically, seen obliquely from above, a set of fourth stator refining segments arranged next to each other; andFigure 7 shows schematically a fifth stator refining segment seen obliquel