EP1679403B1 - Pulper for comminuting and suspending papermaking material - Google Patents

Abstract

The sieve screen (3) has openings (5) with shapes other than circular. The openings are: oval, especially elliptical. They are alternatively slots and/or wavy. The sieve is rotationally-symmetrical. The length (L) of each sieve opening relative to the radius (6) running through the sieve center includes an angle between -80[deg] and +80[deg], preferably between -45[deg] and +45[deg]. The leading edge (10) of the rotor blade runs at an acute angle relative to the length of the sieve openings. This angle is preferably between -45[deg] and +45[deg]. The sieve opening length-to-width ratio is preferably at least 3. Maximum opening width (B) is 4-20 mm. Maximum length (L) is 10-100 mm. The openings are milled, stamped, produced by laser, or by steel-casting. The sieve is a combination of a sieve plate (11) with openings, and a support plate (12). The support plate is a frame- or coarse sieve construction. Its outer contours correspond with those of the plate; its openings are larger than those of the sieve.

Description

The invention relates to a pulper for comminution and suspension of pulp according to the preamble of claim 1.

Pulpers of this type are mainly used to suspend dried pulp or waste paper of various composition. They consist essentially of a container for the suspension and at least one rotor. The registered material is intensively mixed in large pieces, webs or pressed bales with water, whereby a hydraulic material drive is generated by the rotor. Understandably, such devices are optimized, aiming essentially for a fast and efficient dissolution. In many cases, the rotor is placed in close proximity to a flat screen that keeps it free of blockages. Through the openings of the screen, the dissolved substance is sorted by coarse impurities and withdrawn as a suspension. Such a pulper is eg by the EP-A-1 398 410 known. Another open top pulper with a container whose cross-section is not circular shows the FR-A-1 047 321 , Here the sieve is not flat, but conical. It serves to retain the still insufficiently dissolved pulp in the pulper.

The standard type for a pulper is a vertical cylindrical container with a rotor in the bottom area. In this container, water and the substance to be dissolved is added from above and with the help of the rotor creates a Trombenströmung in the suspension, ie in the inner region of the fabric is pulled down from the rotor and pressed radially outwards in the bottom region, resulting in a Umtriebsströmung results. A Another typical design is the open top pulper container with laterally inserted rotor. Then the suspension is conveyed approximately horizontally to the rotor and deflected on the side wall of the container carrying the rotor. This hydraulically often less favorable form has the advantage of finding space under the paper machine as broke dissolver. An example of a Auschussauflöser shows the DE 101 38 860 A1 ,

The previously mentioned sieve initially serves to carry out a separation in which the already sufficiently dissolved fractions of the pulp are drawn off through the openings of the sieve and not yet retained sufficiently dissolved. As a result, the dissolution process becomes more economical in a manner known per se; in particular, the pulper can, if desired, be operated continuously. Contaminants, ie essentially non-paper components, are retained or sorted out.

From the EP-A-1 357 222 is a flat screen for performing a Nasssiebungsverfahrens with slot-shaped screen openings known. It is about higher throughput with the same sorting quality. The process is carried out in closed sorters in which a separation of paper and impurities takes place.

The sieve but also contributes to pulpers of the type mentioned to enhance the dissolution process. The side of the rotor facing the screen plate interacts with the inlet edges of the screen openings. Although a certain distance between rotor and screen plate is always respected, the shear forces that occur are sufficient to further separate the pulp particles. Larger pieces can also bridge the distance between screen plate and rotor, so that a direct cutting effect occurs. The form and intensity of these processes depends on the requirements and the design of the pulper.

It is also known to further reinforce the dissolution effect just described by the fact that the screen plates are provided on the inlet side with strips, as for example from the DE 101 16 367 is known.

From the WO 03/033152 A1 is known a screen plate whose openings have been introduced by laser or water jet. These openings are not round, but provided with corners and preferably distributed like a mosaic on the screen plate. This should increase the dissolution effect.

The known sieves for such pulpers are usually provided with circular holes, a compromise must be found between the demand for optimum classification, ie the smallest possible Sortieröffenungen, and the demand for the highest possible throughput, so the largest possible open area.

The invention is based on the object to improve the known pulpers for the resolution of pulp so that with them the highest possible throughput of dissolved pulp can be achieved without the cost, especially for equipment and operation, rise. In special embodiments, it should also be possible to reduce the equipment costs or the operating costs.

This object is achieved on a pulper according to claim 1 with the features mentioned in the characterizing part of this claim.

Characterized in that the screen plate in the pulper especially with elongated round openings, e.g. Long holes or oval openings is provided, the dissolving power of the pulper, which results from the interaction of rotor and screen plate, can be increased. Due to the curves, the risk of attaching fiber fins or impurities prone to spinning (plastic films) is very low. The elongated shape also means that a larger free screen surface can be produced at approximately the same screen fineness.

It is also possible, by appropriate arrangement of the screen openings, which will be discussed in more detail, to optimize the edges, which form at the inlet into the screen opening, with respect to the dissolution effect. These edges can be arranged at a defined angle (cutting angle) to the sweeping past rotor blade edges.

In many cases, it is possible to ensure a good operation of the pulper even if the sieve is without attached strips, ie that then can be dispensed with the installation of additional strips.

Figur 1:

Den Siebbereich eines erfindungsgemäßen Stofflösers;

Figur 2:

Erfindungsgemäß ausgestaltete Sieböffnungen im Detail;

Figur 3:

Vorteilhafte Anordnung von langlochförmigen Sieböffnungen;

Figur 4 + 5:

Je eine weitere mögliche Anordnung von langlochförmigen Sieböffnungen;

Figur 6:

Sieb, das eine Stützplatte aufweist;

Figur 7:

einen Stofflöser in Seitenansicht;

Figur 8:

einen anderen Stofflöser in Ansicht von oben.

The invention will be explained with reference to drawings. Showing:

FIG. 1:

The sieving area of a pulper according to the invention;

FIG. 2:

In accordance with the invention configured screen openings in detail;

FIG. 3:

Advantageous arrangement of slot-shaped screen openings;

Figure 4 + 5:

Depending on another possible arrangement of slot-shaped sieve openings;

FIG. 6:

Sieve having a support plate;

FIG. 7:

a pulper in side view;

FIG. 8:

another pulper in top view.

In FIG. 1 the sieve region of a pulper according to the invention is shown. It can be seen a rotor 2, which is arranged concentrically with an annular flat screen plate 1 in the pulper, not otherwise shown. The rotor 2 is provided with wings 4 and dimensioned so that it completely or at least for the most part sweeps over the screen surface of the screen 3 during rotation (arrow 7). According to the invention, the screen openings 5 of this screen 3 are not circular as usual but elongated. The graphic representation of the screen openings 5 is not to scale here, but should only identify the screen surface. More details about these screen openings is shown in further figures. For larger sieves, it is customary to first produce these as ring segments, which are then assembled in the pulper to form an entire sieve. In the example shown here, the whole sieve consists of a total of eight segments, four of which are drawn. The sieve segments are screwed for example with an underlying support frame 8. This can - unlike drawn here - be constructed so that it supports the screen even where there are no Siebsegmentgrenzen. Then it is possible to reduce the screen plate thickness and save costs, especially in the production of the screen openings. 5

The FIG. 2 shows a possible embodiment of the screen plate a little more detail. In this case 5 slots are selected for the screen openings with the length L and the width B, wherein the curves are semicircular. The length / width ratio UB here is about 4. In other cases, a length / width ratio of less than 2, for example, 1.7 conceivable. Compared to conventional circular screen openings in pulpers, it may be appropriate to dimension the slot so that its free area corresponds to a circular screen opening. When applying the invention to an open primary pulper (bale or machine broke entry), screen openings having a width B between 10 and 20 mm and length L between 20 and 60 mm are to be regarded as a typical embodiment. In a Sekundärstofflöser, that already works in a closed system, much smaller screen openings, eg with a width B of about 4 mm are provided.

At the opening edges 9, in cooperation with the rotor blades 4 moving close to them, releasing forces are transferred to the suspension, in particular the pulp. Unlike circular screen openings have elongated screen openings in this interaction with the rotor blade 4 a stronger dissolution effect. In addition, they offer an important opportunity to influence the dissolution effect. In particular, the orientation of the elongated screen opening 5 plays an essential role relative to the running through the center of the screen radius 6. In the example shown here, this angle α assumes a value of -5 °. If it is chosen to be relatively small, a stronger dissolution effect is to be expected, since the edge 9 is steep (perpendicular or almost vertical) is flown. With regard to this feature, other forms may be useful, such as FIG. 3 shows, in which the longitudinal side of the slots are aligned exactly in the direction of the radius 6. In the left part of the FIG. 3 For example, sieve openings 5 'with a length / width ratio of 2 are shown.

Another object of the invention is the adjustment of the optimum cutting angle β, the between the leading edge 10 of the Rotorflüsgels 4 and the opening edge. 9 the screen openings is formed. This intersection angle β is in Fig. 2 with 8 ° relatively small, which leads to a strong dissolving effect.

According to the FIGS. 4 and 5 the angle α = 45 °, or α = - can be 45 °, the version according to FIG. 4 the radial transport of the substance favors, while FIG. 5 at least tends to prolong the residence time of the substance in the screening area, since during deflection at the opening edge 9, a radially inwardly directed flow direction is formed. The angles may also be different, eg changing depending on the distance to the center of the screen.

Although the previously discussed slot shapes and their arrangement are typical examples of practicing the invention, they are not the only ones. Thus, e.g. also other oval / oblong shapes are chosen.

In order to reduce the manufacturing costs for the screen openings, the sieve (according to FIG. 6 In general, then the support plate 12 has the same outer contour as the screen plate 11. The passage openings 13 of the support plate 12 may be uneven and substantially larger than the screen openings 5, since they have no screening effect. Because of the support plate 12, the screen plate 11 can be kept relatively thin, which greatly simplifies the introduction of openings.

The most common form of pulper to which the invention can be applied is the standing cylindrical open-top pulper according to FIG FIG. 7 in which sieve 3 and rotor 2 are located in the bottom area. During operation, stock S and water W are introduced into the container 1. The finished pumpable suspension is withdrawn through the sieve 3 as accept A. Such pulpers have long been known. The same applies to pulpers with side mounted rotors according to FIG. 8 , As already mentioned, such a lying container 1 'particularly advantageous under a Paper machine to be used for the dissolution of production committee.

Claims (14)

1. Pulper for comminuting and suspending papermaking material (S), having a container (1, 1') open at the top and having at least one rotor (2) which is arranged in the container (1, 1'), can be driven and has means for circulating a suspension contained in the container, in order in the process to comminute the papermaking material put in and to suspend it in water, and also having at least one screen (3), of which the screen area provided with screen openings is swept over, for the major part or completely, by the moving rotor (2),
   characterized in that
   the screen (3) is provided with elongated round screen openings (5, 5', 5"), the shape of which deviates from that of a circle.
2. Pulper according to Claim 1, characterized in that the screen openings (5) are oval, in particular elliptical.
3. Pulper according to Claim 1, characterized in that the screen openings (5') are slots.
4. Pulper according to one of the preceding claims, characterized in that the screen is annular and flat and in that, with respect to the radius (6) running through the centre of the screen, the length (L) of the screen openings (5, 5', 5") assumes an angle (α) which lies between -80° and +80°, preferably between -45° and + 45°.
5. Pulper according to one of the preceding claims, characterized in that, relative to the length (L) of the screen openings (5, 5', 5"), the leading edge (10) of the rotor blade (4) runs at an angle of intersection (β) between -80° and +80°, preferably -45° and + 45°.
6. Pulper according to one of the preceding claims, characterized in that the screen openings (5, 5', 5") have a length to width ratio of at least 1.5, preferably at least 3.
7. Pulper according to one of the preceding claims, characterized in that the maximum width (B) of the screen openings (5, 5') lies between 4 and 20 mm.
8. Pulper according to one of the preceding claims, characterized in that the length (L) of the screen openings (5, 5', 5") lies between 10 and 100 mm.
9. Pulper according to one of the preceding claims, characterized in that the pulper has a rotor fitted at the side and is suitable for pulping papermachine broke.
10. Pulper according to one of the preceding claims, characterized in that the screen openings (5, 5', 5") are produced by milling.
11. Pulper according to one of Claims 1 to 9, characterized in that the screen openings (5, 5', 5") are produced by punching.
12. Pulper according to one of Claims 1 to 9, characterized in that the screen openings (5, 5', 5") are produced by a laser beam.
13. Pulper according to one of Claims 1 to 9, characterized in that the screen (3), together with the screen openings (5, 5', 5"), is produced in the steel casting process.
14. Pulper according to one of the preceding claims, characterized in that the screen comprises a screen plate (11) containing the screen openings (5, 5', 5") and a supporting plate (12), the supporting plate (12) being a frame or coarse screen structure, the outer contour of which corresponds substantially to that of the screen plate (11) and which is provided with passage openings (13) which are larger than the screen openings (5' 5', 5'').

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