FI12965Y1 - Pulper - Google Patents

Description

The invention relates to a pulper for recycling a fibrous suspension contained in a container, having at least one screen swept over a screen surface provided with elongate screen openings by a rotor, the rotor comprising a rotor head rotating about a rotor shaft and having a plurality of rotor blades attached to its outer circumference.

The invention also relates to a pulper for recycling a fibrous suspension contained in a container having at least one screen swept over by a rotor through a screen surface provided with elongate screen openings, the rotor comprising a rotor head rotating about a rotor shaft, having a plurality of rotor blades attached to its outer circumference. bumps on the rotor circumference of the screen over which the rotor blades sweep.

Pulps of this type are mainly used for slurrying dry cellulosic material or waste papers of different compositions. They consist essentially of a suspension tank and at least one rotor. The fed material is thoroughly mixed with water in large pieces, webs or compression bales, whereby the O mass is hydraulically recirculated by means of a rotor. g N 30 It is understood that such devices are optimized, with the goal of essentially fast E and energy efficient decomposition. In many cases, the rotor is arranged in the immediate vicinity of the flat screen so that it does not become clogged. The decomposed mass is separated from the N 35 coarse impurities through the openings of the sieve and S is removed as a suspension.

The upright cylindrical tank with a rotor at the bottom has established itself as a standard type of pulper. Water is added to this tank from above and the mass to be disintegrated and the rotor produces a vortex flow in the suspension, in which the rotor pulls the mass downwards in the inner part and pushes it radially outwards in the lower part, as a result of which a spiral flow is created.

Another typical design type is a top-open pulper tank with a rotor mounted on its side. In it, the suspension is conveyed approximately horizontally to the rotor and directed to the side wall of the tank supporting the rotor.

This hydraulically often less advantageous shape has the advantage that it can be placed under a paper machine as a waste pulp.

The function of said screen is, firstly, to carry out a separation in which the portions of already sufficiently decomposed pulp are removed through the openings of the screen and the insufficiently decomposed material is retained. This makes the decomposition process more economical in a manner known per se, in particular the pulper can be used continuously if desired. Impurities, i.e., substantially non-paper components, are retained or separated.

It is also known to further enhance the disintegration effect described above by providing the inlet side of the screen plates z with strips, as is known, for example, * from DE 101 16 367. The purpose of these strips is mainly to protect the screen element from wear. For this reason, they are also often made of a highly wear-resistant material, e.g. carbide. > In addition to the wear-reducing effect, they can

however, it also improves the operation of the separator. As the rotor blades move relatively close past the screen element, this relative movement can create additional vortices which help to keep the separation opening clean. If the pulp is fluffy, the interaction of the rotor blade and the bar can lead to a completely undesired flock disintegration. WO 03/033152 A1 discloses a screen plate with apertures cut with a laser or water jet. These openings are not round but angular and are preferably mosaically distributed on the screen plate. The purpose of this is to enhance the dispersing effect.

The known screens of such pulpers are mainly provided with round holes or, as described in EP1677403, with elongated screen openings, in which case a compromise must be found between the optimum sorting requirement, i.e. the smallest possible separation apertures, and the highest possible flow rate, i.e. between a large open area.

The characteristics of such a screen arise essentially from the size, shape and number of screen openings therein.

N N In addition to high flow, 3 30 high hydraulic pressure resistance is also required. To achieve this goal, DE19547585 discloses a screen with a support and separation layer.

a 2 However, the screen openings are still problematic, especially in terms of fabrication, flow-through and N clogging risk.

The object of the invention is to improve the dispersing efficiency while keeping the flow rate as high as possible.

According to the invention, the object is achieved in that the screen has a plurality of annular screen openings arranged in concentric rows around the axis of rotation, and all the screen openings in one row are oriented in the same direction with respect to the direction of rotation. Since all screen openings at the same distance from the axis of rotation are also oriented in the same direction of rotation, the working edge of the rotor blades also sweeps one row over all the screen openings in the same way. The result is a uniform screening effect over the entire screen surface over which the rotor sweeps.

In addition to this, this also makes it possible to adapt the position of the screen openings optimally to the respective part of the working edge of the rotor blades. For this purpose, it may be advantageous if the orientation of the screen openings in the rows is different from the direction of rotation. This is particularly important when the working edge of the rotor blades pointing in the direction of rotation runs at least partially inclined or curved perpendicular to the radial direction from the rotor shaft.

In terms of uniform screening effect, the largest part N, preferably all of the screen openings, should be N oriented in the same way with respect to the respective radial part of the working edge of the rotor blades.

N In general, it has proven advantageous for the long side of the elongate screen openings to form an angle of -30 ... + 30 ° with the working edge of the rotor blades pointing in the direction of rotation 2 of the rotor.

= 35 S If the screen has rib-like protrusions, at least> in the direction of rotation of the rotor, the screen openings arranged immediately in front of the protrusions should also be oriented with respect to the cutting edge of the protrusion indicating the direction of rotation. "This also ensures a smooth screening effect. 5 Especially in the area in front of the bumps, there is turbulence and dam action as the rotor blades sweep over. In order to allow only small contaminants to pass through the screen openings, the screen should be parallel to the cutting edge of the bump. Accordingly, the long opening edges of the screen openings arranged immediately in front of the protrusions in the direction of rotation of the rotor should form an angle of 60-120 ° with the process edge of the protrusion showing the direction of rotation and the fiber in the process. depending on the type of fibrous raw material or the shape and size of the tank, screen surface or rotor, it may then be advantageous if the area of the over-swept screen surface is to be adjusted, depending on the type of fibrous raw material or the shape and size of the container, screen surface or rotor. the working edge and / or the cutting edge of the protrusions of the rotors are at least partially, preferably substantially straight or at least partially formed, N preferably substantially straight parts or running at least partially, preferably substantially curved.

N z In terms of load and wear, as well as to simplify the structure, it is advantageous if the screen is configured to be rigid. = 35 8

D

Depending on the size of the tank or the type and location of the rotor, it may then be advantageous if the screen surface is curved or flat.

By providing the pulper screen with particularly elongate screen openings, for example longitudinal holes or oval, in particular elliptical screen openings, the disintegration efficiency of the pulper due to the interaction of the rotor and the screen can be increased.

In addition, the cross-section of the elongate screen openings can advantageously be limited only by four circular sections of different lengths with different radii, whereby the long circular sections with large radii and the short circular sections with small radii alternate.

The circular structure of the screen openings has a positive effect on the production by laser cutting, because there is no need to change the speed, as would otherwise be the case when cutting corners.

In addition, the exclusively rounded edges of the screen openings considerably improve the power of the rotor when wiping over them.

In addition to the reduced risk of clogging, it is also possible to optimize the open surface area and durability of the screen.

N In this case, advantages can arise when one long circular part of the elongate N sieve opening runs concavely 3 30 curved with respect to the center N of the cross section of the sieve opening and the three circular parts run convexly = curved. * Namely, the side of the rotor facing the screen 2 interacts with the inlet edges of the screen openings = 35. However, a certain gap is always kept S between the rotor and the screen, although the shear forces present in this case are still sufficient to break up the pulp particles.

cassette. Larger pieces can also bypass the gap between the screen and the rotor, so that a direct shear effect occurs.

The side of the screen opening in the direction of rotation plays a particularly important role in the interaction with the rotor. Thanks to the concave curvature of this side, the disintegration of the fluff flocs can be substantially improved and the flow-through can be increased.

If the front side of the rotor pointing in the direction of rotation moves towards the concavely curved mouth portion of the screen opening, the pulp flow is distributed at both ends of the concave curvature, which enhances the processing of the pulp.

In order to make the concave curvature as large as possible, the screen openings should have only one concavely curved round part at a time.

The cutting angle between the working edge of the rotor blades pointing in the direction of rotation and the cutting edge of the protrusions pointing against the direction of rotation should remain radially outwards at least partially unchanged and / or increase at least partially.

This ensures that the dirt can travel radially outwards along the cutting edge of the protrusion and does not stick between the rotor blade and the protrusion. This helps keep the screen clean and reduces N wear. In addition, this prevents the further grinding of impurities, in particular plastic particles, so that they can be more easily removed to the wreck. Less comminution also has process technical and energy advantages.

S N 35 Dirt particle size, velocity, and web line S are important factors. If the particles are smaller> than the gap between the rotor and the protrusion, then they are usually also smaller than the perforation of the screen and do not cause major problems.

If, on the other hand, the dirt particle is larger, it must now be led out and must not get caught between the rotor and the bulge or screen.

The dirt particles are brought to a certain speed both by the resistance forces of the suspension and by contact with the rotor.

It is often sufficient for the cutting angle between the working edge and the cutting edge to remain the same radially outwards. However, in order to achieve the desired effect, it is advantageous if the cutting angle between the working edge and the cutting edge remains radially outwards the same for at least 2/3 of the length of the working edge or even the entire length of the working edge.

The least wear in the protrusions occurs when the same constant cutting angle between the working edge of the rotor and the cutting edge of the protrusion is 90 ”, because the fibers and impurities then move radially outwards parallel to the respective protrusion.

However, the radially outward displacement of the impurities can be enhanced by increasing the cutting angle between the working edge and the cutting edge radially outwards. The impurities are thus pushed out of the nip.

N In this connection, it is advantageous if the cutting angle between the working edge z and the cutting edge increases radially outwards by at least 2/3 of the length of the working edge or even over the entire length of the working edge.

= 35 S In this case, it has proved to be optimal for the disintegration and wear of the mass when the cutting angle between the working edge and the cutting edge is 80-120 ”, preferably 80-110”. The invention will be explained in more detail below by means of several embodiments.

In the accompanying drawing: Fig. 1: shows a schematic longitudinal section through a pulper; Figure 2: shows a partial section through the sieve 2 of the pulper; Fig. 3: shows a top view of a screen 2 provided with a rotor 4; Fig. 4: shows another partial top view of the screen 2 and the rotor 4 with the cutting angle 15 being the same constant and partially increasing; Fig. 5: shows a partial top view of the screen 2 and the rotor 4 with the working edges 8 straight; Fig. 6: shows a partial top view of a screen 2 with concentrically arranged rows 19 of screen openings 3 and protrusions 9; Figures 7 to 10: show elongate screen openings 3 with different cross-sections, and Figures 11: show a partial top view of a screen 2 with a protrusion 9. As shown in Figure 1, the pulper is formed from above an open cylindrical container 10, N to which fiber raw material and water are added.

The rotor 4 used 3, which has a plurality of rotor blades 7, takes care of thorough mixing z and grinding of the fibrous raw material and slurrying in water.

The pulp density of the pulper is then 2-7%. 3 = 35 The circular screen 2 divides the container 10 into two chambers.

The material discarded by the screen 2 is discharged through a discharge 16.

The accept in the form of a fiber suspension 1 removed through the screen openings 17 through the screen openings 17 is further processed in the following devices and processed into paper webs in a paper machine.

During rotation, the rotor 4 or its rotor blades 7 sweep the screen 2 over the screen surface provided with elongate screen openings 3 and thus prevent it from clogging. The rotor 4 is dimensioned with its rotor blades 7 so that, as it rotates, it sweeps completely or at least for the most part over the screen surface of the screen 2. The screen 2 and the rotor 4 in front of it are most often located at the bottom of the container 10, as can be seen from Figure 1.

However, it may also be advantageous or necessary to arrange this in the wall of the container. Such horizontal powders are used especially below the paper machine for handling the reject.

Due to the load on the screen 2 and to simplify manufacturing, this is configured to be flat and rigid. In the case of larger screens 2, it is customary to make these first into ring segments, which are then assembled in a pulper into a single whole screen 2, as shown in Fig. 6.

NN The elongate sieve openings 3 consist essentially of two opposite long opening edges N 13 and, in between, two short opening edges 18. In particular, in the long opening edges * 13 the disintegrating forces are transmitted to the suspension 1 by interaction with the rotor blades 7, which move - = 35 vat from near them. In contrast to the round sieve openings 3, the elongate sieve openings 3 have a stronger dispersing effect. Their orientation also offers an important opportunity to influence the decomposition efficiency.

In this regard, Figs. 9 and 11 show oval screen openings 3, Fig. 8 a bean-shaped screen opening 3 and Fig. 10 a screen opening 3 in the form of a longitudinal hole.

The cross-section of the elongate screen openings 3 is limited at least approximately exclusively by four circular sections of different lengths of different radii, with the long circular sections with large radii and the short circular sections with small radii alternating.

In the embodiment shown in Fig. 7, one long circular portion of the elongate screen opening 3 runs concavely curved with respect to the center of the cross section of the screen opening 3, while the three circular portions run convexly curved. The concave round part projecting into the screen opening 3 then promotes the disintegration effect.

The rotor 4 takes care of the decomposition of the fibrous raw material and the decomposition of the flocs on the one hand, and on the other hand of removing any impurities or foreign substances from the screen surface. The axis of rotation 5 of the rotor 4 is then perpendicular to the screen surface.

N The rotor 4 has a relatively large rotor N head 6, on the outer circumference of which six rotor blades 7 are attached by way of example 3 30. The large N rotor head 6 can be used to effectively prevent the movement of insoluble, rotating raw material (plates or bales). ).

N 35 S On the side facing the rotor 4, a screen 2 with a plurality of rib-like protrusions 9 is provided, as shown in Figs. 1 and 2, which enhances the disintegration and cleaning effect. These rib-like protrusions 9 have a height of at least 2 mm from the screen surface and can be configured as a fixed screen with the screen 2 or as a separate element, or they can in each case be formed from a welding fire. The cutting edge 14 of the protrusions 9 pointing against the direction of rotation 11 can then pass at least partially straight or curved.

In order to achieve a better disintegration effect, in particular also in interaction with the protrusions 9, it is most often advantageous if the working edge 8 of the rotor blades 7 pointing at least partially inclined (Fig. 5) or curved (Figs. 3 and 4) perpendicular to the rotor shaft 5 . In order to ensure that the working edge 8 of the rotor blades 7 interacts as evenly as possible with the elongate screen openings 3 during rotation, all the screen openings swept by the rotor blades 7 are arranged in a plurality of annular rows 19 around the axis 5 of rotation. all the screen openings 3 of one row 19 are likewise oriented with respect to the direction of rotation 11. To complete this, all the screen openings 3 are N oriented in the same way with respect to their respective radial part of the working edge 8 of the rotor blades 7. Since the working edge 8 3 30 runs obliquely or curved with respect to the radial direction 12 N, it follows that the orientation of the screen openings z 3 of the rows 19 is different with respect to the direction of rotation 11. * In order to achieve a better dispersing effect, the long opening edge 13 of the sieve openings 3 forms here = 35 in connection with an angle of -30 ... + 30 ° with the working edge 8> of the rotor blades 7 pointing in the direction of rotation 11 of the rotor 4.

In order to have a uniform effect, the screen openings 3 arranged in the direction of rotation 11 of the rotor 4 immediately in front of the protrusions 9 should also be oriented with respect to the cutting edge 14 of the protrusion 9 indicating the direction of rotation 11.

Regardless of this, the long opening edges 13 of the screen openings 3 arranged immediately in front of the protrusions 9 against the direction of rotation 11 of the rotor 4 should form an angle of 60-120 *% with the cutting edge 14 of the protrusion 9 indicating the direction of rotation 11. This orientation of the elongate screen openings 2 prevents the passage of larger contaminants, which is important due to the dynamic pressure generated in front of the protrusions 9.

With respect to the interaction between the rotor blade 7 and the protrusion 9, it is essential that the cutting angle 15 between the working edge 8 of the rotor blades 7 and the cutting edge 14 of the protrusions 9 pointing against the direction of rotation 11 remains radially outward over the entire radial dimension of the protrusions 9 or is shown in Figure 3, it grows radially outwards and is thus 90-110 ”.

Fig. 4 shows in this respect another variant in which the cutting angle 15 remains the same in the case of the protrusion 9 shown by the solid line and increases in the case of the protrusion 9 shown by the broken line in the radially outer part of the screen 2N.

N 3 30 In order to simplify operation with as many N rotor structures as possible, it may be advantageous to assemble the protrusions 9 from several straight parts, although * this keeps the cutting angle 15 only partially unchanged and / or partially increased.

= 35 S The working edge 8 of the rotor blades 7 pointing in the direction of rotation 11 of the rotor 4 is convexly curved in the direction of rotation 11, as can be seen from Figures 3 and 4. However, if necessary, the working edges 8 can also have completely or at least partially straight parts according to Fig. 5.

Particularly in parts where the wear of the protrusions 9 is higher, for example in the case of a radially outwardly increasing cutting angle 15 between the working edge 8 and the cutting edge 14, it may be advantageous if the width of the protrusions 9 increases radially outwards. In addition, the protrusions 9 can also extend only to the radial part of the screen 2. This allows optimizations, especially when the wear of the protrusions 9 is uneven.

Irrespective of the special structure of the working edge 8 of the rotor 4 and the cutting edge 14 of the protrusions 9, it is generally ensured that the working edges 8 of the rotor blades 7 push the impurities radially outwards along the cutting edges 14 of the protrusions 9. As a result, the risk of dirt sticking between the rotor vane 7 and the protrusion 9 is reduced, which has a correspondingly positive effect on wear. Thus, in addition, the optimization of resistance and shear forces is realized, combined with better dissipation and lower energy consumption.

OF O OF

O <Q

OF

I Jami a

O

O +

OF O OF D

Claims (20)

PROTECTION REQUIREMENTS A pulper for recycling a fiber suspension (1) contained in a container (10) having at least one screen (2) swept over by a rotor (4) over a screen surface provided with elongate screen openings (3), the rotor (4) comprising a rotor shaft ( 5) a rotating rotor head (6) with a plurality of rotor blades (7) attached to its outer circumference, characterized in that the screen (2) has screen openings (3) arranged in a plurality of annular rows (19) concentric around the axis of rotation (5) and all the screen openings (3) of one row (19) are likewise oriented with respect to the direction of rotation (11). Pulper according to Claim 1, characterized in that the orientation of the screen openings (3) in the rows (19) is different from the direction of rotation (11). Pulper according to Claim 2, characterized in that a plurality, preferably all, of the screen openings (3) are also oriented with respect to their radial part of the working edge (8) of the rotor blades (7). Pulper according to one of the preceding protective claims, characterized in that the long opening edge (13) of the screen openings (3) forms an angle of -30 ... + 30 ° to the rotor blades (11) pointing in the direction of rotation (11) of the rotor (4). 7) with the working edge (8). Pulper according to one of the preceding claims, in particular for recirculating the fibrous suspension (1) contained in the container (10), having at least N one screen (2), which is swept over by a rotor N over a screen surface with elongate screen openings 3 30 (3). (4), wherein the rotor (4) comprises a rotor head (6) rotating about a rotor shaft (5) Ek, on the outer circumference of which a plurality of rotor blades (7) are attached * and having 2 several rib-like protrusions (9) on the rotor head of the screen (2). with which the rotor blades (7) sweep, characterized in that the long opening edges (13) of the screen openings (3) arranged immediately in front of the protrusions (9) of the rotor (4)> 60-120% with the cutting edge (14) of the protrusion (9) indicating the angle of rotation (11). Pulper according to Claim 5, characterized in that the screen openings (3) arranged in the direction of rotation (11) of the rotor (4) immediately in front of the protrusions (9) are also directed towards the cutting edge (14) of the protrusion (9) pointing against the direction of rotation (11). ). Pulper according to Claim 5 or 6, characterized in that the cutting edge (14) of the protrusions (9) runs at least partially straight. Pulper according to one of Claims 5 to 7, characterized in that the cutting edge (14) of the protrusions (9) runs at least partially curved. Pulper according to one of the preceding protective claims, characterized in that the elongate screen openings (3) are oval, in particular elliptical. Pulper according to one of Claims 1 to 8, characterized in that the elongate screen openings (3) are longitudinal holes. Pulper according to one of Claims 1 to 8, characterized in that the cross-section of the elongate screen openings (3) is limited exclusively by four circular parts of different lengths of different radii and long circular sections with large radii and short circular sections with small radii alternating. . OF Pulper according to protective claim 11, characterized in that one long circular part of the elongate screen opening (3) runs concavely curved with respect to the center of the cross-section of the screen opening (3) and * the three round parts run convexly curved. 2 Pulper according to one of Claims 5 to 12 = 35, characterized in that the working edge (8) of the rotor blades (7) pointing in the direction of rotation (11) and the protrusions (9) pointing against the direction of rotation (11) intersect. the cutting angle (15) between the fringe edge (14) remains radially outwards at least partially unchanged and / or increases at least partially. Pulper according to Claim 13, characterized in that the cutting angle (15) between the working edge (8) and the cutting edge (14) remains radially outwards the same for at least 2/3 of its length, preferably over the entire length of the working edge (8). Pulper according to Claim 13 or 14, characterized in that the same constant cutting angle (15) between the working edge (8) and the cutting edge (14) is 90 °. Pulper according to Claim 13, characterized in that the cutting angle (15) between the working edge (8) and the cutting edge (14) increases radially outwards by at least 2/3 of its length, preferably over the entire length of the working edge (8). Pulper according to one of the preceding protective claims, characterized in that the working edge (8) of the rotor blades (7) runs at least substantially straight. Pulper according to one of Claims 1 to 16, characterized in that the working edge (8) of the rotor blades (7) runs at least substantially curved. Pulper according to one of the preceding protection claims, characterized in that the screen (2) is configured flat. N pulper according to one of Claims 1 to 18, characterized in that the screen (2) is curved. & O <Q OF I Jami a O O + OF O OF D