EP2370629A1

EP2370629A1 - Method for refining aqueous suspended cellulose fibers and refiner fillings for carrying out said method

Info

Publication number: EP2370629A1
Application number: EP09736233A
Authority: EP
Inventors: Markus FÜRSATTEL; Tillman Katzenmeier; Hans-Hermann Kleinschnittger
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2008-11-28
Filing date: 2009-10-16
Publication date: 2011-10-05
Also published as: DE102008059610A1; US20110278385A1; CN102245832B; WO2010060685A1; BRPI0916127A2; CN102245832A; US8789775B2

Abstract

The invention relates to a method for refining aqueous suspended cellulose fibers, wherein said fibers are guided in an aqueous suspension (S) between refiner fillings (1, 2) provided with refining strips (6) and interposed grooves (3), located either on a rotor (9) or a stator (8) and being rotably moved relative to each other and pressed against each other, thereby transmitting mechanical refining action to the cellulose fibers. According to the invention, refiner fillings (1, 2) are used, in which barriers (4, 4’) are present in at least part of the grooves (3), said barriers closing said grooves (3) at least partially.

Description

Process for grinding aqueous suspended pulp fibers and grinding sets for its implementation

The invention relates to a method according to the preamble of claim 1.

It has long been known that pulp fibers, i. H. Frischzellstoff- or waste paper fibers, placed in a pumpable suspension and ground. As a result, the individual fibers are changed so that the paper produced therefrom has the desired properties, in particular strengths, formation and surface. Milling methods of the type considered here use grinding tools, which are provided with grinding strips designated as knives. The corresponding machines are usually called Mahlrefiner. The grinding tools are usually referred to as trimmings.

Milling sets for milling pulp fibers with grinding bars and grooves in between are e.g. known from DE 20 2005 007 551 U1.

The invention is based on the object to provide a process for pulp milling, with which it is possible to carry out the grinding economically and particularly evenly, i. that the achieved grinding technological changes are largely the same for all fibers. This should also be possible in particular if relatively narrow grinding strips in the range from 1 mm to 5 mm are used.

This object is achieved by the features mentioned in claim 1.

The claims 27 to 31 describe in each case for the process particularly suitable Mahlgarnituren. With the help of these described features, it is possible to favorably influence the flows of the fiber suspension in and between the Mahlgarnituren. The grooves located between the milling strips are to be regarded as flow channels for the suspension. It can be assumed in disc and Kegelrefinern that occurs as a result of the rotational movement of the rotor and entrained by him pulp suspension a more or less strong pressure build-up from the radially inner to the radially outer regions. Due to this pressure difference takes place in the non-rotating grooves, ie between the blades of the stator, at least partially, a back flow of the suspension from radially outside to radially inside instead. On the way the backflowing suspension travels within a groove, a transition can take place from the open side of the groove to the counterset. The barriers according to the invention promote the escape of the suspension from the grooves located between the milling strips into the grinding zone, that is to say at the knife edges which meet. This repetition of the milling processes, the grinding is uniform, which is technologically and energetically of particular advantage.

Another advantage of the invention is that the barriers can be used to reduce or eliminate the risk of the suspension being conveyed too quickly through the grooves of the rotor assembly, which would lead to less grinding and to unnecessary energy consumption.

In principle, the said barriers can be used both in the fittings of the stator and those of the rotor or both.

Grinding processes of this kind are carried out at a temperature below 100 degrees Celsius, ie without appreciable steam generation and typically at a consistency of between 2 and 8%. In many cases, a Mahlgarnitur for methods of this kind is constructed so that the largest possible number of knives can accommodate it, for. B. to optimize the effect of grinding by reducing the specific Katenbelastung. Then the flow channels become relatively narrow. Grinding processes with such Working sets are improved by the invention particularly effective. Advantageously, the trimmings used for the process on grinding strips with rectilinear grinding edges, which can also be unsteady, so have break points.

The invention and its advantages will be explained with reference to schematic drawings. Showing:

FFiigg .. 11 :: the implementation of the method using the example of a Scheibenrefiners;

Fig. 2 + 3: each a part (sector) of a usable according to the invention

Grinding set in plan view;

Fig. 4 -8: Variants in shape and size of the barriers;

Fig. 9: a barrier in perspective view; FFiigg .. 1100 :: a garment sector with axially offset barriers;

FIG. 11: a garment sector with grinding edges having buckling points; FIG.

Fig. 12: Implementation of the method using the example of a cone refiner.

The method according to the invention can be carried out in a grinding device, as shown schematically in section in FIG. On a stator 8 is a Mahlgarnitur 1 and on a rotor 9, a grinding set 2 releasably secured by means of screws 12. The Mahlgarnituren 1 and 2 are knife sets, which are provided with Mahlleisten 6, which can be seen for example in Figs. 2 and 3 in plan view. In the example shown here, the suspension S to be grounded passes through the center of the stator 8 into the grinding sets 1 and 2. In this illustration, the axial distance between the grinding sets 1 and 2 is greatly exaggerated. In operation, it is only fractions of a millimeter. The suspension S passes through the cooperating Mahlgarnituren 1 and 2, exits at the discharge side again, collects in the annular space 7 and leaves at least partially the annular space 7 via a corresponding nozzle as a ground suspension S ^' . - A -

The rotor 9 is driven by a shaft 11. Not shown are the means known per se, with which a force is generated to press the two Mahlgarnituren against each other or adjust the grinding gap.

In the example shown here, both on the stator 8 and the rotor 9 barriers 4 and 4 ^'are mounted in the grooves 3 with the effect already described. Their arrangement will be explained by way of examples in FIGS. 2 and 3.

According to FIG. 2, a barrier 4 ^'is used in each groove 3 on the grinding set 1 belonging to the stator 8. Your radial extent b may be short, z. B. 5 to 30 mm. The barriers 4 ^' are here arranged by the radially innermost edge of the grooves at a radial distance a2, which is about 70% of the radial extent L of these grooves 3, with advantage at least 50%. In the case of the grinding set 2 provided for the rotor 9 (see Fig. 3), the barriers 4 are arranged from the radially innermost edge of the grooves at a radial distance a1 which is approximately 30% of the radial extent L of these grooves 3, with advantage at most 50%. By this arrangement, the flowing in the grooves 3 of the rotor 9 suspension is pushed out relatively early from the provided with barriers 4 grooves in the direction of the stator 8 and ground.

As already mentioned, a part of the suspension flows back after exiting the radially outer edge of the rotor assembly back through the lying between the Mahlleisten 6 grooves 3 in the stator 8. The return flow is braked by stator side barriers 4 ^' and the suspension again in the Grinding area passed between cooperating sets. In the above-described arrangement of the barriers 4 ^' , this transition is relatively early, z. B. on the first third of the flow path in the stator.

Typically, the grinding set shown in FIG. 2 is used with further outwardly located barriers 4 ^' on the stator 8 and that according to FIG. 3 with further inwardly located barriers 4 on the rotor 9, which also corresponds to the principle illustrated in FIG. It is but quite conceivable that the barriers are arranged just reversed, z. B. if it turns out to be an advantage that the backflow in the grooves of the stator and the flow in the grooves of the rotor assembly meets relatively late on a barrier.

Depending on how large the desired effect, each groove 3 may be provided with a barrier 4 or 4 ^' or even a part of them, for. B. every second, third or fourth groove. FIG. 3 shows an example in which every other groove contains a barrier 4.

In most cases, the grooves 3 are each equipped with at most one barrier 4 or 4 ^' , the distance a1 or a2 from the radially innermost edge of the grooves 3 being equal for all barriers 4 or 4 ^{' of the} same clothing. It is furthermore advantageous if the distances a 1 and a 2 of interacting sets (rotor / stator) moving relative to one another differ significantly, for example by at least 10%.

If the wear in the area of the barriers is very high, it may be favorable to place adjacent barriers of a set axially offset in order to distribute the wear over a larger area. An example is shown in FIG. 9. In this case, this aspect must be weighed against the requirement of uniform grinding, which is to be expected at equal distances a1 and a2.

It is also possible to provide the grooves each with a plurality of barriers, especially in sets with large groove length.

As the Fig. 4, 5, 7 and 8, the barriers 4 or 4 ^{'may have} a height h equal to the groove depth t so as to extend to the grinding edges of the grinding bars 6. Fig. 6, however, shows a barrier 5 with only 80% of the groove depth t amounting amount h, which therefore closes only a part of the groove. Even such a lower barrier 5 can be quite effective hydraulically. 4, 5, 6, 7 and 9 show favorable embodiments in which the flowed guide surfaces of the barriers 4, 4 ^' and 5 are chamfered in order to achieve better flow guidance at this point. Such a chamfer 13 or 13 ^' advantageously extends over at least 80% of the height h of the barrier. The pitch angle α or α ^' is then at least 15 degrees, z. B. between 45 and 89 degrees. A similar effect can possibly also be achieved with a rounding off on the inflow side according to FIG. 8. Rounding or chamfering may also be particularly advantageously applied to both sides of the barriers, as an example in FIG. 5 shows. Particularly in the case of millings used on the stator side, the flow conditions can be further improved.

The grinding edges 15 can be rectilinear, which simplifies the production of the sets and fluidly favorable. As FIG. 11 shows, one or more break points 15 can also change the angle to the radius, in particular if this produces a more favorable cutting angle of the encountered grinding edges of cooperating grinding sets (rotor 9 with stator 8).

The method can also be designed so that in addition to the, in particular in combination with the measures described in the claims, the flow cross section in the grooves 3 is changed by different groove depth t. Thus, the groove depth increases or decreases from the inside to the outside, the increase of the groove depth t in the stator and the decrease in the rotor being particularly advantageous. This also makes it possible to influence the return flow in the grooves, in particular to promote the transfer of the suspension flowing back into the grooves into the grinding zone.

Should the process be carried out with a cone refiner; then this can be done as shown in FIG. 12. One recognizes there a the constructions 1 ^' bearing internal conical stator 8 and a coaxial Außenkegeligen rotor 9 with the Mahlgarnituren 2 ^' . Since cone refineries are known, further descriptions of these machines are not necessary here. Both stator and rotor side barriers 4, 4 ^'are mounted between the grooves, with respect to number, shape and arrangement what has been said in connection with disk-shaped Mahlgarnituren.

Claims

Voith Patent GmbH File: RPS14162 WO89522 Heidenheim "'Ramp'" claims

1. A process for grinding aqueous pulp fibers, in which these fibers in an aqueous suspension (S) between Mahlleisten with (6, 6 ^' ) and intervening grooves (3) provided Mahlgarnituren (1, 1 ^' , 2, 2 ^' ) be guided on either a rotor (9) or a stator

(8) and are rotated relative to each other and pressed against each other, whereby mechanical grinding work is transferred to the pulp fibers, characterized in that at least partially Mahlgarnituren (1, 1 ^' , 2, 2 ^' ) are used, in which at least in one part the grooves (3) barriers (4, 4 ^' , 5, 5 ^' ) are present, which close these grooves (3) at least partially.

2. The method according to claim 1, characterized in that at least part of the in the grooves (3) flowing fiber suspension through the barriers (4, 4 ^' , 5, 5 ^' ) out of the grooves (3) is led out.

3. The method according to claim 1 or 2, characterized in that the barriers (4, 4 ^' , 5, 5 ^' ) are arranged from the radially innermost edge of the grooves at a radial distance (a1) which is at most 50%, preferably at most 30th % of the radial extent (L) of these grooves (3) is.

4. The method according to claim 1 or 2, characterized in that the barriers (4, 4 ^' , 5, 5 ^' ) from the radially innermost edge of the grooves (3) are arranged at a radial distance (a2) which is at least 50%, preferably at least 70% of the radial extent (L) of these grooves (3).

5. The method according to any one of the preceding claims, characterized in that with barriers (4, 4 ^' , 5, 5 ^' ) provided Mahlgarnituren (2, 2 ^' ) on the rotor (9) are used.

6. The method according to claim 5, characterized in that with barriers (4, 4 ^' , 5, 5 ^' ) provided Mahlgarnituren (2, 2 ^' ) are used only on the rotor (9).

7. The method according to any one of claims 1 to 5, characterized in that with barriers (4, 4 ^' , 5, 5 ^' ) provided Mahlgarnituren (1, 1 ^' ) on the stator (8) are used.

8. The method according to claim 5 and 7, characterized in that provided with barriers (4, 4 ^' , 5, 5 ^' ) Mahlgarnituren (1, 1 ^' , 2, 2 ^' ) on the rotor (9) and on the stator ( 8) that the barriers (4, 4 ^' , 5, 5 ^' ) are arranged on the rotor (9) from the radially innermost edge of the grooves at a radial distance (a1) which is at most 50%, preferably at most 30% the radial extent (L) of these grooves (3) is, and that the barriers (4, 4 ^' , 5, 5 ^' ) are arranged on the stator (8) from the radially innermost edge of the grooves at a radial distance (a2) at least 50%, preferably at least 70% of the radial extent (L) of these grooves (3).

9. The method according to claim 5 and 7, characterized in that with barriers (4, 4 ^', 5, ^5') provided with grinding tools (1, 1 ^', 2, ^2') on the rotor (9) and on the stator (8) are used, that the barrier ( 4, 4 ^' , 5, 5 ^' ) are arranged on the rotor (9) from the radially innermost edge of the grooves at a radial distance (a2) which is at least 50%, preferably at least 70% of the radial extent (L) of these grooves (3 ), and that the barriers (4, 4 ^' , 5, 5 ^' ) on the stator (8) from the radially innermost edge of

Grooves are arranged at a radial distance (a1) which is at most 50%, preferably at most 30% of the radial extent (L) of these grooves (3).

10. The method according to any one of the preceding claims, characterized in that the radial distances (a1, a2) of the barriers (4, 4 ^' , 5, 5 ^' ) from the radially innermost edge of the grooves (3) in cooperating Mahlgarnituren (1 , 1 ^' , 2,

2 ^' ) differ by at least 10%, preferably at least 30% from one another.

11. The method according to any one of the preceding claims, characterized in that at least a part of the adjacent barriers (4, 4 ^' , 5, 5 ^' ) of a clothing (1, 1 ^' , 2, 2 ^' ) from the axis of rotation of the rotor ( 9) has the same distance.

12. The method according to any one of the preceding claims, characterized in that at least a portion of the adjacent barriers (4, 4 ^' , 5, 5 ^' ) of a set is arranged offset from one another in the radial direction.

13. The method according to any one of the preceding claims, characterized in that the Mahlleisten (6, 6 ^' ) are provided with rectilinear grinding edges (14).

14. The method according to claim 13, characterized in that the grinding edges (14) in each case a Mahlleiste (6 ^' ) are discontinuous by having at least one inflection point (15).

15. The method according to any one of the preceding claims, characterized in that at least 80% of the grinding surface lying between the grinding bars (6, 6 ^' ) grooves (3) with a tolerance of -10% to + 10% constant

Groove width (N) have.

16. The method according to any one of the preceding claims, characterized in that on at least 80% of the grinding surface, the groove depth (t) of between the

Grooves (6) lying grooves (3) between 3 and 20 mm, preferably between 3 and 10 mm.

17. The method according to any one of the preceding claims, characterized in that on at least 80% of the grinding surface Mahlbar (6, 6 ^' ) with a tolerance of -10% to + 10% have a constant blade width (M).

18. The method according to any one of the preceding claims, characterized in that the Mahlleisten (6, 6 ^' ) at least in the region of the barriers (4, 4 ^' ) a blade width (M) of at least 1 mm and at most 30 mm, preferably at most 5 mm.

19. The method according to any one of the preceding claims, characterized that the barriers (4, 4 ^') have at least 50%, preferably at least 80% of their height (h) at least one chamfer ^(13,13') whose pitch angle (α, α ^') in its relations to the Gru nd the jeweil N ut (3) is at least 15 degrees, in particular at least 45 degrees.

20. The method according to claim 19, characterized in that the bevel (13) on the radially inner side of the barrier (4) on the rotor (9) used Mahlgarnitur (2) or Mahlgarnituren (2).

21. The method according to claim 19 or 20, characterized in that the chamfer (13 ^' ) on the radially outer side of the barrier (4 ^' ) on the stator (8) used Mahlgarnitur (1) or Mahlgarnituren (1).

22. The method of claim 19, 20 or 21, characterized in that the barriers (4, 4 ^' ) on both sides with bevels (13, 13 ^' ) are provided.

23. Method according to one of the preceding claims, characterized in that the height (h, h ^' ) of at least part of the barriers (4, 4 ^' ) above the bottom of the respective groove (3) is between 30% and 100%. the groove depth (t), preferably between 50% and 80%.

24. Method according to one of the preceding claims, characterized in that the height (h, h ^' ) of at least part of the barriers (4, 4 ^' ) over the bottom of the respective groove (3) corresponds to the groove depth (t).

25. Method according to one of the preceding claims, characterized in that each groove (3) is provided with at most two, preferably at most one barrier (4, 4 ^' ).

26. The method according to any one of the preceding claims, characterized in that only every second, third, fourth or fifth groove (3) of the used Mahlgarnituren (1, 1 ^' , 2, 2 ^' ) with a barrier (4, 4 ^' ) is provided.

27. Mahlgarnitur (1, 1 ^' , 2, 2 ^' ) for applying the method according to one of the preceding claims, which is provided with Mahlleisten (6, 6 ^' ), between which grooves (4) are, characterized in that at the Mahlgarnitur (1, 1 ^' , 2, 2 ^' ) at least in a part of the grooves (3) barriers (4, 4 ^' , 5, 5 ^' ) are present, which at least partially close them.

28. grinding set (1, 1 ^' , 2, 2 ^' ) according to claim 27, that the barriers (4, 4 ^' , 5, 5 ^' ) from the radially innermost edge of the grooves (3) arranged in a Rad ialen distance (a1) are at most 50%, preferably at most 30% of the radial extent (L) of these grooves (3).

29. Mahlgarnitur (1, 1 ^' , 2, 2 ^' ) according to claim 27, characterized in that the barriers (4, 4 ^' , 5, 5 ^' ) from the radially innermost edge of the grooves (3) at a radial distance (a2 ) are arranged, which is at least 50%, preferably at least 70% of the radial extent (L) of these grooves (3).

30. Mahlgarnitur (1, 1 ^' , 2, 2 ^' ) according to claim 27, 28 or 29, characterized the milling strips (6, 6 ^' ) are provided with rectilinear grinding edges (14).

31. Mahlgarnitur (1, 1 ^' , 2, 2 ^' ) according to claim 30, characterized in that the grinding edges (14) in each case a Mahlleiste (6 ^' ) are discontinuous by having at least one articulation point (15).