EP3411522B1 - Rotor blade, and screen comprising a rotor blade - Google Patents

Description

The subject of this invention is a wing for sorters, which are usually used for the treatment of a pulp suspension. The wing is attachable to the rotor and has a front and rear edge. The subject of this invention also forms a sorter with the wings according to the invention.

A sorter for purifying a pulp suspension according to the prior art is in FIG. 1 shown. It has a rotor 1 and a strainer 8. The rotor 1 rotates about the rotor axis 2. The direction of rotation of the rotor 1 is indicated by an arrow. On the rotor 1 a plurality of wings 3 are screwed on mounting holes 7 on the brackets 4. Of course it is also possible to fix the wings by welding. The wing distance to the screen basket 8 is shown here with y.

The wings 3 have viewed in plan a straight front edge 5 and a straight trailing edge 6. In cross-section, they have a wing profile, but other shapes are possible here and in use.

In operation, 8 pressure and suction pulses and turbulence triggered by the wings 3 at the perforation (holes or slots) of the screen basket. As a result, clogging of Siebkorböffnungen is prevented. The operation of a sorter is very energy-intensive and thus expensive due to the generation of these pulses and turbulences. From the pamphlets EP2203590A1 . WO2012084562A1 . DE102009014810A1 . EP1143065A2 . US3939065A . DE69424661T2 . WO9401618A1 . CN104532652A . DE6012137T2 Rotor blades are also known with a curved leading edge. The US Pat. No. 3,939,065 discloses a rotor body with protrusions, which have a curved leading edge and a slightly curved trailing edge. The EP 1 143 065 A2 discloses a wing with straight, obliquely rearward leading and trailing edges.

The invention is therefore based on the object to improve conventional wings or sorters so that they require less energy at least the same cleaning performance.

This problem is solved by wings which, viewed in the wing ground plan, on the one hand have a curved front edge or a curved envelope of the front edge. The curvature takes place in the direction of the trailing edge. On the other hand, the trailing edge or the envelope of the trailing edge is curved in the same direction as the leading edge. In cross-section, the wing spaced from the rotor according to the invention has an airfoil profile, wherein the curved wing top faces the screen basket.

Surprisingly, this new design has found that sorters with appropriate blades require less energy for the same or even better cleaning performance.

The curved front edge also better distributes the pressure impulse caused by the wing onto the screen basket. As a result, the locally acting forces are reduced to the screen basket and increases the service life of the basket. Furthermore, there is a very flat pulsation pattern on the sorter side, allowing the use of this sash for paper machine headbox sorters where lowest pressure variations are required.

The leading edge may be symmetrical, for example circular arc, curved from the middle of the wing to the wing tips.

In one embodiment, the front edge is step-shaped, so that the envelope in the direction Trailing edge is curved. Preferably, then, the trailing edge is formed stepwise.

Such a wing shape can be produced, for example, when a conventional wing with straight front and rear edge is broken into individual slices, the cut surfaces are normal to the leading edge. The slices are then offset from the middle of the wing to the rear edges towards the trailing edge and then joined together again. This results in a wing with stepped front and rear edges whose envelopes are each curved backwards. If the original wing has an airfoil, you also get a partially stepped wing top or wing bottom ( Fig. 8 and Fig. 9 ) which in turn improves the flow behavior.

It is advantageous if webs are provided on the wing surface, which run from the front edge to the trailing edge. These webs do not have to start directly at the leading edge, but can also be made shortened. These webs can be present both on the side facing the screen basket and on the side facing the rotor.

In one possible embodiment, the leading edge or its envelope and the trailing edge or its envelope curve are equally curved and the airfoil profile substantially the same over the entire blade length.

The wing can be wider in the front area (area that is first moved through the pulp suspension) than in the rear area, ie the distance between the wings both end points of the front edge is then greater than the distance between the two end points of the trailing edge.

The invention also relates to a sorter for treating a pulp suspension with a rotor having the wings according to the invention.

The wings can be mounted parallel to the rotor axis or at an angle. Due to the inclination of the wing (see Fig. 6 ), the load on the screen basket can be further reduced. The pitch of the wings may be different in the various rows of wings to be at an optimum angle to the material spiral flow. This angle preferably ranges from 0 ° to +/- 25 °.

The inclination of the wings may be such that, in operation, the upper wing tip is leading the lower wing tip or the lower wing tip is leading the upper wing tip.

Likewise, both inclinations can be performed on a rotor. Thus, the residence time of the stock suspension in the rotor body and screen basket can be adjusted and optimized. The residence time depends on the type of pulp, or on the consistency and the flow behavior of the suspension.

It is advantageous if the distance y of the individual vanes from the sieve basket varies over the rotor height z.

Thus, for example, the wings arranged in the upper inlet area of the sorter can travel closer to the screen basket than the wings arranged in the lower area or vice versa (depends on the type of fibrous material, or from the consistency and the flow behavior of the suspension).

• Fig. 1 einen herkömmlichen Sortierer nach dem Stand der Technik, wie er bereits oben beschrieben wurde.
• Fig. 2 einen Grundriss eines erfindungsgemäßen Flügels;
• Fig. 3 einen Querschnitt durch den Flügel gemäß Fig. 2 mit einer möglichen Ausführung mit Schraubenbefestigung;
• Fig. 4 einen Sortierer mit den erfindungsgemäßen Flügeln nach Fig. 2 und 3;
• Fig. 5 einen Grundriss eines weiteren erfindungsgemäßen Flügels;
• Fig. 6 einen Sortierer mit den Flügeln nach Fig. 5;
• Fig. 7 einen Grundriss eines weiteren erfindungsgemäßen Flügels, der im hinteren Bereich schmaler ist;
• Fig. 8 einen Grundriss eines erfindungsgemäßen Flügels, bei dem die Vorderkante und die Hinterkante stufenförmig ausgebildet sind;
• Fig. 9 einen Querschnitt durch den Flügel gemäß Fig. 8;
• Fig. 10 einen weiteren Sortierer mit erfindungsgemäßen Flügeln;

Hereinafter, some embodiments of the invention will be described with reference to drawings. Show it:

• Fig. 1 a conventional sorter of the prior art, as already described above.
• Fig. 2 a floor plan of a wing according to the invention;
• Fig. 3 a cross section through the wing according to Fig. 2 with a possible version with screw fastening;
• Fig. 4 a sorter with the wings of the invention after Fig. 2 and 3 ;
• Fig. 5 a floor plan of another wing according to the invention;
• Fig. 6 a sorter with wings behind Fig. 5 ;
• Fig. 7 a plan view of another wing according to the invention, which is narrower in the rear area;
• Fig. 8 a plan view of a wing according to the invention, in which the front edge and the rear edge are formed step-shaped;
• Fig. 9 a cross section through the wing according to Fig. 8 ;
• Fig. 10 another sorter with wings according to the invention;

Like reference numerals in the respective figures indicate like components.

In FIG. 2 an embodiment of the wing 10 according to the invention is shown. It has a front edge 11 which, viewed in plan view, is curved in the direction of the trailing edge 12. This direction is indicated by an arrow and the reference numeral 23. The leading edge 11 is symmetrically curved with respect to the wing center line 24. On the wing center line 24 are also the two mounting holes 13 for receiving the mounting screws. The leading edge 11 ends at the wing edges in the end points 14 and 15 whose connecting line is denoted by the reference numeral 16. The distance between the two end points 14 and 15 is marked with a.

The trailing edge 12 is also curved in the direction 23 and indeed as strong as the leading edge 11. The trailing edge 12 terminates at the wing edges in the end points 31 and 32, the distance between these two points 31 and 32 is marked b. Both distances a and b are equal here or the wing 10 is uniformly wide. Both edges 11, 12 are curved in a circular arc.

FIG. 3 shows a cross section through the wing 10 from FIG. 2 , It can be seen here well the airfoil profile, the curved top points to the screen basket.

FIG. 4 shows a sorter with a strainer 8 and a rotor 1 on the plurality of wings 10 according to FIG. 2 and 3 are mounted. The wings 10 in the edge regions are not shown here for clarity. The height of the rotor 1 is denoted by z. The wings 10 are here distributed over the rotor height z distributed in three planes, of course, more or fewer levels can be provided. In FIG. 4 the wings 10 are arranged over the circumference relative to the height Z in each case one plane, so that the wings 10 of different levels paint over different Siebkorbbereiche. The wings 10 can also be arranged offset over the height z of the rotor 1, so that wings 10 of different levels cover the same screen basket areas.

All wings 10 are in Fig. 4 arranged parallel to the rotor axis 2, that is, the connecting line 16 of the two end points 14 and 15 of the wing leading edge 11 is parallel to the rotor axis. 2

FIG. 5 shows a wing 10, which the wing 10 in FIG. 2 is very similar, but here are not both mounting holes 13 on the wing center line 24. This wing 10 is mounted obliquely on the rotor 1, as shown in FIG. 6 is shown. The connecting line 16 of the two end points 14 and 15 of the wing leading edge 11 is therefore not parallel to the rotor axis 2, but forms with this in cross-section viewed an angle α of +/- 20 °, preferably of +/- 10 °.

The wing 10 according to FIG. 5 has on the wing inside (the side facing away from the screen basket 8) three webs 19 and on the wing outer side (the screen basket 8 side facing) two webs 20. These webs 19, 20 have a favorable effect on the flow behavior, of course, more or fewer webs 19th or 20 are provided. The two Wing edges 17 and 18 run parallel here, ie the wing is uniformly wide.

In FIG. 7 a wing 10 is shown, which in contrast to the wing 10 in FIG. 5 The two wing edges 17, 18 are thus not parallel or the distance a between the two end points 14 and 15 of the leading edge 11 is greater than the distance b between the two end points 31 and 32 of the trailing edge 12th

In FIG. 8 is another inventive wing 10 shown in plan. The front edge is here stepped, as well as the trailing edge in such a way that the envelope 21 is curved in the direction of the trailing edge. The trailing edge envelope 22 is curved in the same direction but, in the present example, is stronger than the trailing edge envelope 21.

In FIG. 9 the wing is 10 off FIG. 8 shown in cross section, you can see well the wing profile. The individual wing segments 101, 102 and 103 all have an airfoil profile and are narrower at the rear than at the front. The wing segments 101, 102 and 103 are offset from each other, so that thereby results in the stepped front and rear edge. In addition, webs are thereby formed on the wing top and wing underside. This wing 10 is narrower than the front by the slightly wedge-shaped segments 101, 102 and 103 behind. The distance a of the two end points 14 and 15 of the leading edge is therefore greater than the decency b of the two end points 31 and 32 of the wing trailing edge. Of course it is also conceivable that both distances a and b are equal, so that the wing side edges 17 and 18 are parallel.

The wing 10 according to Fig. 8 is not only suitable for a straight mounting on the rotor 1, but can also be mounted obliquely through the elongated mounting hole 13, ie that the connecting line 16 of the two end points 14 and 15 is not parallel to the rotor axis 2. With this variant, a customized adjustment of the angle for the particular application is possible. It is also conceivable that the wing leading edge 11 is not formed step-like but wavy or can also be performed wavy wing surface.

In FIG. 10 another sorter with the wings 10 according to the invention is shown. The wings 10 are formed asymmetrically and attached to the rotor 1 at its upper edge region.

Claims (15)

1. Blade (10) for screens used to treat a fibrous pulp suspension, where the blade (10) can be secured to a screen rotor (1) and where the blade (10) has a leading edge (11) and a trailing edge (12), where the leading edge (11) or an envelope curve (21) of the leading edge (11) is arched in the direction (23) of the trailing edge (12) when viewed in a horizontal projection, where the trailing edge (12) or the envelope curve (22) of the trailing edge (12) is also arched in the same direction (23) as the leading edge (11) when viewed in a horizontal projection, characterised in that the blade (10) can be secured at a distance from a rotor (1) and that the blade (10) has a cross-section with a wing-shaped profile, where the leading edge (11) forms the profile nose.
2. Blade (10) according to claim 1, characterised in that the leading edge (11) is curved symmetrically from the middle of the blade (24) towards its ends (17, 18).
3. Blade (10) according to claim 2, characterised in that the leading edge (11) or the envelope curve (21) of the leading edge (11) is curved in an arc shape.
4. Blade (10) according to one of claims 1 to 3, characterised in that the leading edge (11) is stepped and the envelope curve (21) is curved in the direction (23) of the trailing edge (12).
5. Blade (10) according to claim 4, characterised in that the trailing edge (12) is also stepped and that the envelope curve (22) of the trailing edge (12) is arched.
6. Blade (10) according to one of claims 1 to 5, characterised in that bars (19, 20) are provided on the upper side of the blade.
7. Blade (10) according to one of claims 1 to 6, characterised in that the leading edge (11) or its envelope curve (21) and the trailing edge (12) or its envelope curve (22) are arched equally, and the wing-shaped profile is largely the same over the entire length of the blade (a) when viewed in cross-section.
8. Blade (10) according to one of claims 1 to 6, characterised in that the leading edge (11) or its the envelope curve (21) and the trailing edge (12) or its envelope curve (22) are curved to different extents.
9. Blade (10) according to one of claims 1 to 6, characterised in that the spacing (a) between the two endpoints (14, 15) of the leading edge (11) is larger than the spacing (b) between the two endpoints (31, 32) of the trailing edge (12).
10. Blade (10) according to one of claims 1 to 9, characterised in that the blade has at least two fastening holes (13) for securing the blade (10) to a rotor (1), where at least one fastening hole (13) is slot-shaped so that the fastening position on the rotor (1) is adjustable.
11. Screen for treating a fibrous pulp suspension with a rotor (1) and a screen basket (8), where several blades (10) are secured to the rotor (1), characterised in that the blades (10) are shaped according to one of claims 1 to 10.
12. Screen according to claim 11, characterised in that the blades (10) are secured to the rotor (1) in such a way that a straight line (16) between the two endpoints (14, 15) of the leading edge (11) runs in parallel to the rotor axis (2).
13. Screen according to claim 11, characterised in that the blades (10) are secured to the rotor (1) on a slant such that a straight line (16) between the two endpoints (14, 15) of the leading edge (11) does not run in parallel to the rotor axis (2).
14. Screen according to one of claims 11 to 13, characterised in that several blades (10) are mounted over the rotor height (z) and the spacing (y) between the blades and the screen basket (8) varies over the rotor height (z).
15. Screen according to one of claims 13 or 14, characterised in that several blades (10) are mounted over the rotor height (z) and that the blades are secured at different slants.

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