TECHNICAL FIELD

The invention is related to an apparatus for manufacturing fibre pulp from lignocellulose-containing material, according to the preamble of claim 1 .

BACKGROUND

A disk refiner or grinder comprises a housing enclosing two opposed refining disks, at least one of which is rotary. The refining disks each have refining elements, between which a refining gap is formed for disintegrating lignocellulose-containing material, such as chips from soft- or hardwood, bamboo, straw, bagasse or similar into fibre pulp. The pulp leaves the refiner via a space on the rear side of the rotary refining disk. A problem is that the pulp sticks to said rear side of the rotary refining disk and to the housing and also create forces to the bearings which may destroy them. Build ups of burnt fibre bindles or particles may later come loose and create problems further down the line in other processing steps. A common problem is e.g. spots on board.

It is known to have straight wing elements aligned along thought radial lines on the rear side of the rotary refining disks to prevent pulp to stick to the rear side and/or the housing. A problem with them is that they are not efficient enough. Further, they have a tendency to create turbulence, which creates wear.

SUMMARY

An object of the invention is to solve the problems with an invention as in claim 1 . By placing the wing members in a positive angle from a thought radial line and towards a direction of rotation, a better cleaning and less wear of the rear side of the rotary refining disk is obtained. Further, energy can be saved since the direction of the transportation of the particles will be more directed towards the circumference of the refining disk, where an outlet preferably is located. .

Other advantages may be obtained by the different embodiments in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further objects and advantages thereof, may best be understood by reference to the following description and appended drawings, in which:

Fig. 1 is a schematic cross-sectional view illustrating an apparatus according to an exemplifying embodiment of the invention.

Fig. 2 is a schematic front view illustrating the apparatus in Fig. 1 according to an exemplifying embodiment of the invention.

Fig. 3 is a schematic front view illustrating the apparatus in Fig. 1 according to another exemplifying embodiment of the invention. Figs. 4a-e are schematic views illustrating the apparatus in Fig. 1 according to further exemplifying embodiments of the invention.

DETAILED DESCRIPTION

In Fig. 1 and 2 a refiner 1 according to the invention is disclosed, which is an example of an apparatus 1 for manufacturing fibre pulp from lignocellulose- containing material. The refiner 1 comprises a housing 2 enclosing a stationary refining disk 3, also called stator, and a rotary refining disk 4, also called rotor. The stationary refining disk 3 may be connected to the housing 2. The rotary refining disk 4 is driven by a motor (not shown) through a rotary shaft 5 and preferably rotates with 1500-2300 rpm. It is also possible to have two rotating refining disks 3, 4. The refining disks 3, 4 are provided on their surfaces facing towards each other with refining elements 6, 7, which between themselves define a refining gap 8, which preferably is 0.1 -2 mm.

The stationary refining disk 3 has an inlet 9, through which material to be refined is fed into the gap 8. It is preferable to preheat the material with e.g. steam before feeding into the refiner 1 and to refine under pressure in the refiner 1 . It is also possible to have chemical treatment of the material before feeding into the refiner 1 .

In the gap 8, the material is preferably first crushed into thin sticks, which by the centrifugal force are fed outwards to a grinding zone, where the fibres are uncovered and worked so that they become soft and so that the surfaces of the fibres get a good binding capability.

A space 10 is provided between the housing 2 and a rear side 1 1 of the rotary refining disk 4. The material processed in the refiner 1 is collected in the space 10 and leaves the refiner 1 through an outlet 18.

The rear side 1 1 of the rotary refining disk 4 is provided with a centre 14 and a circumference 17. At least one thought radial line 13 extends at least from the centre 14 to the circumference 17.

To prevent the processed material from sticking to the rear side 1 1 of the rotary refining disk 4 and to the housing 2, the rear side 1 1 is also provided with at least one wing member 12. The wing members 12 can be part of the rotary refining disk 4 by e.g. making larger or smaller cutouts in the rear side 1 1 between where the wings members 12 are going to be. However, the wing members 12 are preferable separate from, but attached to the rotary refiner disk 4, because then the wing member 12 can easily be replaced when worn and may also be made from a different material than the rotary refining disk 4, preferably harder. Harder material is often more expensive and since the wing member 12 is a wear part, then the area of the wing members 12 is preferably smaller than the area between the wing members 12. Further, the manufacture of the refiner 1 is simplified if the wing members 12 are separate from the rotary refiner disk 4, instead of having to make cutouts in the rotary refining disk 12.

Instead of placing all the wing members 12 straight radially aligned, at least one wing member 12 is at a positive angle a, a1 , a2, a3 larger than zero, e.g. around 45°, from a thought radial line 13, towards the direction of rotation R. Different wing members may be at an angle a, a1 , a2, a3 to different thought radial lines 13. The wing members 12 are preferably placed in a pattern that points in a direction opposite to the direction of rotation R. A pattern is defined as one set of wing members 12 that are arranged between the rotary shaft 5 and the circumference 17. A pattern may then be repeated symmetrically around the rotary shaft 5. Since the wing members 12 are at an angle a, a1 , a2, a3 with a thought radial line 13, the wing members 12 work better than if they had been placed straight radially aligned, since the material is thrown out more efficiently from the centre 14 of the rotary refining disk 4. This gives better cleaning and less wear. Further, energy can be saved since the direction of the transportation of the material will be more directed towards the circumference 17 of the rotary refining disk 4, where the outlet 18 preferably is located.

In Fig. 2, all wing members 12 are at the same angle a from the thought radial lines 13. However, preferably, as in Fig. 3, the wing members 12c further from the centre 14 of the rotary refining disk 4 are arranged at a smaller angle a3 (which in this case may be as small as 0°), than the wing members 12b, 12a closer to the centre 14 of the rotary refining disk 4, which wing members 12b, 12a are placed at increasingly larger angles a2, a1 . This is because the rotation speed of the material is lower closer to the centre 14 and thus a larger angle is preferred.

Small, straight, separate wing members 12, 12a, 12b, 12c as in Fig. 2 and 3 are most economical, since they are cheapest to manufacture and you only need to replace the wing members 12, 12a, 12b, 12c that are most worn and therefore not necessarily all at the same time. A stronger attachment may, however, be gained if the wing members 12 are provided with a collar 15, which fits in a corresponding notch 16 in the rear side of the rotary refining disk 4.

In Fig. 4a-c is shown schematically other alternatives of wing members 12 where the wing members 12 go more or less the whole way from the rotary shaft 5 to the periphery 17 of the rotary refining disk 4. The wing members 12 may be straight or curved and may have equal or varying width. There may be one wing member 12 going all the way from the rotary shaft 5 to the periphery 17 of the rotary refining disk 4 as in Fig. 4a and 4b. Or else there may be a number of separate wing members 12 arranged from the rotary shaft 5 to the periphery 17, either spaced apart as in Fig. 2, 3, 4d and 4e or overlapping as in Fig. 4c. For stability the wing members 23 are preferably arranged symmetrical with respect to the rotary shaft 5. The figures show 2-4 patterns, but more are possible. The invention is of course not restricted to the shown embodiments, but may be varied within the scope of the claims.