PULP DEWATERING CLOTHING FOR A PULP DEWATERING MACHINE

Abstract

A pulp dewatering fabric includes a pulp-side first woven fabric layer for receiving the cellulose pulp material to be dewatered and a running-side second woven fabric layer. The first woven fabric layer is formed with first longitudinal threads which run in a belt longitudinal direction and first transverse threads which run in a belt transverse direction. The second woven fabric layer is formed with second longitudinal threads which run in the belt longitudinal direction and second transverse threads which run in the belt transverse direction. The first woven fabric layer and the second woven fabric layer are joined to one another by connecting threads. Second floats are formed by the second longitudinal threads or the second transverse threads on a running-side outer side.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of PCT application No. PCT/EP2012/051003, entitled “PULP DEWATERING FABRIC FOR A PULP DEWATERING MACHINE”, filed Jan. 24, 2012, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The current invention relates to a pulp dewatering clothing which is utilized in a pulp dewatering machine in the embodiment of a continuous belt, in order to move the cellulose pulp material forward through the machine while removing liquid, generally water from the cellulose pulp material.

2. Description of the Related Art

To provide a dewatering characteristic of this nature, pulp dewatering clothing is generally composed of a woven structure, comprising a pulp-side first fabric layer on which the pulp material to be dewatered is placed and a machine-side second woven fabric layer, whereby this second woven fabric layer is in contact with the various rollers which move the clothing forward, or respectively redirect it in a pulp dewatering machine. The two woven fabric layers each comprise first and respectively second longitudinal threads progressing in the longitudinal direction of the belt, and first and respectively second cross threads which are interwoven with these longitudinal threads. The interconnection of the two woven fabric layers occurs through binding threads, tied partially into the first woven fabric layer and partially into the second woven fabric layer and respectively tying off with wires of these two woven fabric layers.

What is needed in the art is a pulp dewatering fabric for a pulp dewatering machine which, with favorable dewatering characteristic, offers a high retention capacity for fibers contained in the pulp and at the same time a high mechanical stability.

SUMMARY OF THE INVENTION

The present invention provides a pulp dewatering clothing for a pulp dewatering machine, including a pulp-side first woven fabric layer for receiving the cellulose pulp material to be dewatered and a machine-side second woven fabric layer, wherein the first woven fabric layer is formed with first longitudinal threads which progress substantially in a longitudinal direction of the belt, and first cross threads which progress substantially in a direction transverse to the longitudinal direction of the belt. The second woven fabric layer is formed with second longitudinal threads which progress substantially in the longitudinal direction of the belt, and second cross threads which progress substantially in the transverse direction. The first woven fabric layer and the second woven fabric layer are joined to one another by binding threads. Second floats are formed by the second longitudinal threads or the second cross threads on a machine-side outer side, wherein a maximum and/or mean float length of the second floats is greater than a maximum and/or mean float length of first floats which are formed by the first longitudinal threads or the first cross threads on a pulp-side outer side.

The current invention combines two aspects with the respective float lengths in the two woven fabric layers. On the one hand, through comparatively shorter floats on the side intended to receive the pulp material a greater number of support points, or respectively a comparatively uniform structure, is achieved, ensuring increased mechanical retention, in other words improved retention capacity for fibers contained in the pulp material and at the same time providing good dewatering characteristics. On the other hand, because of longer floats on the side of the clothing which is in contact with the drive- or turn rollers, the threat of so-called fibrillating, in other words disintegration of the longitudinal or respectively cross threads in the second woven fabric layer into individual fibers due to mechanical load during operation, as occurs especially due to the tensile load caused by the forward movement in longitudinal direction and also in press nips which contribute to intensified dewatering, is reduced.

A very efficient reduction in the threat of fibrillating can be achieved in that the second floats have a float length in the range of between approximately 2 to 11, for example 3 to 9, or approximately 7, and/or the first floats have a float length of a maximum of 4.

At the same time it is possible to optimize the retention capacity on the side intended to receive the pulp material in that the first woven fabric layer is formed as a plain weave or a rib weave. Other types of weave, for example twill- or satin weave are possible.

The floats formed at the two outer sides can be formed by the same thread types of longitudinal threads and cross threads, so that these floats progress therefore in the same direction, either in the longitudinal direction or in the transverse direction. In an alternative embodiment, different thread types of longitudinal threads and cross threads can be used at the two outer sides, so that for example the floats formed on the pulp-side outside progress in the longitudinal direction, whereas the floats formed on the machine-side outside progress in the transverse direction.

An especially efficient protection of the second longitudinal threads which absorb a substantial share of the longitudinal load and which are heavily stressed mechanically on the machine-side outer side can be achieved in that first longitudinal threads and/or binding threads progressing in the longitudinal direction in the first woven fabric layer are offset relative to second longitudinal threads and/or binding threads progressing in the transverse direction in the second woven fabric layer.

In particular it may be provided that one type of thread of longitudinal threads and cross threads is provided by warp threads and the other type of threads of longitudinal threads and cross threads is provided by weft threads, and that the warp threads of the first woven fabric layer and warp threads of the second fabric layer are offset relative to each other in a weft direction. Due to this offset positioning the longitudinal threads of especially the first woven fabric layer, viewed in a thickness direction of the clothing, support themselves not only on one single longitudinal thread of the second fabric layer positioned directly underneath, but instead on several or respectively two such longitudinal threads in the second woven fabric layer, resulting in an improved load distribution.

To join the two fabric layers it may be provided that the binding threads include binding thread pairs consisting always of two adjacently positioned binding threads assigned to each other as pairs which continue a weave structure of the first woven fabric layer. In an arrangement of this type the binding threads are therefore structure-forming or respectively structure-continuing, whereby it may be provided that each time such a binding thread pair effectively replaces or respectively provides one binding thread of the first woven fabric layer and insofar in regard to the entire weave structure of the first woven fabric layer is also considered as a single binding thread.

Alternatively it may be provided that the binding threads include binding threads not continuing the weave structure of the first woven fabric layer, or tying off with the first longitudinal threads or the first cross threads.

According to an additional aspect, the current invention relates to a pulp dewatering machine, wherein at least one pulp dewatering clothing having the previously discussed structure is provided.

To keep the load on the clothing/clothings provided in such a pulp dewatering machine as low as possible it is suggested that the machine does not include a press nip. Instead, arrangements for dewatering of the pulp material may provide that two pulp dewatering fabrics are routed around at least one turning roller in a twin-wire region.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a top or respectively a thread progression in a pulp dewatering clothing according to the present invention;

FIGS. 2a-c illustrate the progression of the warp threads of the clothing illustrated in FIG. 1, as allocated to the numerically depicted weft threads;

FIG. 3 is an alternative arrangement of the pulp dewatering clothing illustrated in FIG. 1;

FIG. 4 illustrates progressions of the weft threads of the fabric relative to the numerically depicted weft threads shown in FIG. 3;

FIG. 5 is an illustration of an alternative arrangement of the thread progression of the dewatering clothing shown in FIG. 4;

FIG. 6 is an additional illustration of an alternative arrangement of the dewatering clothing shown in FIG. 4;

FIG. 7 is an additional illustration of an alternative arrangement of the dewatering clothing shown in FIG. 4;

FIG. 8 is a top view onto a pulp dewatering fabric of the present invention with the progression of warp- or respectively weft threads shown in FIG. 7;

FIG. 9 is an additional alternative arrangement of a pulp dewatering clothing according to FIG. 1;

FIG. 10 is an additional alternative arrangement of a pulp dewatering clothing according to FIG. 1;

FIG. 11 is a progression of weft threads of the clothing illustrated in FIG. 10 with reference to the numerically depicted warp threads;

FIG. 12 is an illustration of an alternative arrangement of the illustration shown in FIG. 11;

FIG. 13 is an additional illustration of an alternative arrangement of the pulp dewatering clothing in FIG. 1; and

FIG. 14 is a schematic diagram of a pulp dewatering machine according to the present invention.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly to FIGS. 1 and 2, there is shown a top view of respectively thread progressions in a pulp dewatering clothing 10. Pulp dewatering clothing 10 is in the embodiment of a woven fabric and includes a pulp-side first woven fabric layer 12 and a machine-side second woven fabric layer 14. First woven fabric layer 12 is arranged with a multitude of first longitudinal threads 16 extending in a longitudinal direction L, in other words in a machine direction of the generally continuous clothing 10, and with first cross threads 18 extending in a transverse direction, in other words in a cross-machine direction. The second woven fabric layer is arranged with second longitudinal threads 20 extending in longitudinal direction L, and second cross threads 22 extending in cross-direction Q. In one variation first longitudinal threads 16 and second longitudinal threads 20 are provided as warp threads, whereas first cross threads 18 and second cross threads 22 are provided as weft threads.

Clothing 10 illustrated in FIG. 1 is warp tied, meaning that the connection between first woven fabric layer 12 and second woven fabric layer 14 occurs through binding threads 24 in the embodiment of warp threads extending in longitudinal direction L. Here, always immediately adjacent binding threads are allocated to each other, forming a respective binding thread pair in such a way that they continue the weave structure provided in first woven fabric layer 12, in this case a plain weave. In regard to the weave structure provided in first woven fabric layer 12, such a pair of immediately adjacent binding threads 24 effectively provides a single binding thread. As can be seen in FIGS. 2a to 2c, at the location where one of binding threads 24 which are allocated to each other in pairs ties off in the first fabric layer 12 in a plain weave, the other of the two binding threads of a respective binding thread pair is always arranged between the two woven fabric layers 12, 14 and ties off on cross threads 22 under—in other words on the machine side—of second woven fabric layer 14. By repetitively alternating between the two woven fabric layers a plain weave structure is formed overall also in the first woven fabric layer 12 through the two binding threads 24 which are allocated to each other in pairs.

It is also seen in FIG. 1 that second cross threads 20, that is cross- or respectively weft threads 22, arranged in second woven fabric layer 14 provide two floats 28 on machine-side outer side 26, extending always under two second longitudinal threads 20. In first woven fabric layer 12, within the framework of the therein formed plain weave, first cross threads 18 provide first floats 32 on a pulp-side outside 30, extending always over a first longitudinal thread 16. This means, that the maximum float length as well as the median float length in second woven fabric layer 14 is greater on the machine-side outside 26 than the float length of the first floats on the pulp-side outside 30.

Various advantages are gained by this previously discussed structure. Firstly, a very uniform distribution of support points is provided on pulp-side outside 30 for the pulp and respectively for the pulp fibers contained therein, received on this side. This results in a very effective retention capacity, thus preventing penetration of pulp fibers through the fabric structure. At the same time the longer second floats 28 in second woven fabric layer 14 protect second longitudinal threads 20 which, due to the forward movement of clothing 10 in longitudinal direction L, absorb a substantial share of the load, in particular if a clothing of this type is moved through press nips. The threat of fibrillating, in other words disintegration, of the comparatively heavily stressed first longitudinal threads 20 into individual fiber elements can thereby be clearly reduced.

It can also be seen in FIG. 1 that first longitudinal threads 16 and/or first cross threads 18, as well as binding threads 24 providing first woven fabric layer 12 have a smaller diameter than second longitudinal threads 20 and/or second cross threads 22 substantially providing second woven fabric layer 14. For the threads providing the weave structure of first woven fabric layer 12, a diameter in the range of approximately 25 to 100% of the threads providing second woven fabric layer 14 may be provided, which may be intended for first longitudinal threads 16 and for second longitudinal threads 20 in the embodiment of warp threads.

An alternative arrangement is shown in FIGS. 3 and 4. Here it can be seen that woven fabric layers 12, 14 are weft- connected, in other words the binding threads 24 which are provided for interconnection and which also in this case are, for example, assigned to each other in pairs are provided by weft threads. Whereas the float length of first floats 32 formed on the pulp-side outside 30 is 1 also in this case, second floats 28 formed on machine-side outside 26 have a float length of 7, meaning that they extend over 7 second longitudinal threads 20. It can be further seen in FIG. 3 that the mutual distance of first longitudinal threads 16 varies or alternates between a larger distance a′ and a smaller distance a. This also contributes to a better mechanical retention.

It is also pointed out that in the structure illustrated in FIGS. 3 and 4 the warp ratio between the warp threads provided in first woven fabric layer 12 and the warp threads provided in second woven fabric layer 14 is 1:1, whereas the weft ratio is 3:2.

Referring now to FIG. 5, there is shown a variation of the structure illustrated for example in FIG. 3, wherein at a float length of second floats 28 of 7 and of first floats 32 of 1, and at a warp ratio of 1:1 the weft ratio is 2:1.

Referring now to FIG. 6, there is shown the thread progressions of clothing 10 for a pattern repeat (as is the case with the other arrangements) wherein a rib weave is formed in first woven fabric layer 12. This means, first cross threads 18 extend alternating always over and under two first longitudinal threads 16, so that a float length of 2 of first floats 32 is provided here. The float length of second floats 28 is 7 also in this arrangement. Here too a warp ratio of 1:1 is provided, whereas the weft ratio is 2:1.

Whereas FIG. 6 shows clothing 10 having a uniform rib structure in first woven fabric layer 12 as well as in second woven fabric layer 14, clothing 10 having a uniform rib structure only in second woven fabric layer 14 is illustrated in FIGS. 7 and 8. As in the arrangement illustrated in FIG. 6, binding threads 24 connecting woven fabric layers 12, 14—in this case provided by weft threads—are tied into the weave structure of first woven fabric 12, thus continuing same.

Referring now to FIG. 9, there is shown clothing 10 wherein the pulp-side, that is the first woven fabric layer 12 is arranged as a plain weave. Binding threads 24—in this case provided by weft threads—are basically not tied into the plain weave structure of first woven fabric layer 12. In reality they tie off only selectively over first longitudinal threads 16, that is warp threads of first woven fabric layer 12; other than that however they progress between the two woven fabric layers 12, 14 or respectively tie off under second longitudinal threads 20 of second woven fabric layer 14.

In the lower depiction of FIG. 9, which is a cross sectional view in cross direction Q, it can be clearly seen that first longitudinal threads 16 of first woven fabric layer 12 are offset relative to first longitudinal threads 20 of second woven fabric layer 14 in cross direction Q, whereby basically a warp ratio of 1:1 is provided between first woven fabric layer 12 and second woven fabric layer 14. This results in that first longitudinal threads 16 are positioned approximately centered between two second longitudinal threads 20. Under pressure load this results in that not only one straight-line support contact is created between one first longitudinal thread 16 and a second longitudinal thread 20 disposed directly under same, but instead the load is always distributed to two threads in the other layer. This reduces the threat of fibrillation. At the same time very good dewatering characteristics are achieved through the open structure of second woven fabric layer 14, which is supported by provision of a weft ratio of 2:1.

Protection of second longitudinal threads 20 of second woven fabric layer 14 is achieved by second cross threads 22 floating always under four such second longitudinal threads 22.

Referring now to FIGS. 10 and 11, there is shown clothing 10 with second cross threads 22 always floating over 7 second longitudinal threads 20, in other words a float length of 7 of second floats 28. On outside 30 or respectively in first woven fabric layer 12, a plain weave is provided. Immediately adjacently located binding threads 24—in this case also in the embodiment of weft threads—are tied into the fabric structure, that is into the plain weave of first woven fabric 12. In the lower part of FIG. 10 and also in FIG. 11 it is clearly visible that with a warp ratio of 3:2 always groups of 5 threads consisting of three first longitudinal threads 16 and two second longitudinal threads 20 develop in which the first longitudinal threads 16 are offset in cross direction Q relative to second longitudinal threads 20 positioned under them, and for example also have a small cross sectional dimension. Thereby a more uniform load on first longitudinal threads 16 and second longitudinal threads 20 is achieved. Due to the clearly visible difference in drawing 10 of the cross sectional dimension between first longitudinal threads 16 and second longitudinal threads 20, a very fine structure is achieved in first woven fabric layer 12 at high stability of second woven fabric layer 14. The weft ratio in this arrangement is also at 3:2.

A variation of the arrangement described above is illustrated in FIG. 12. Here too, first longitudinal threads 16 are offset in the cross direction—in this case in the weft direction—relative to second longitudinal threads 20—in this case in the weft direction. In this arrangement however, the weft ratio is at 2:1, wherein here too binding threads 24 in the embodiment of weft threads are assigned to each other in pairs, and wherein through such a binding thread pair a collective binding thread is effectively provided, continuing the weave structure of first woven fabric layer 12.

Referring now to FIG. 13, there is illustrated clothing 10, wherein second cross threads 22 of second woven fabric layer 14 float under ten second longitudinal threads 20, thereby protecting them on machine-side outside 26. Binding threads 24 which in this case are in the embodiment of warp threads are basically assigned to each other in pairs so that they continue the plain weave structure of first woven fabric layer 12. The lateral distance of binding threads 24 assigned to each other in pairs is however somewhat greater in this instance, so that in the cross direction between the two binding threads 24 representing such a pair always a second longitudinal thread 20 is positioned. This results in that here too, binding threads 24 are offset in cross direction Q relative to second longitudinal threads 20 and that as a result of this a more uniform support of them can be achieved.

Referring now to FIG. 14, there is shown a schematic illustration of pulp dewatering machine 40 in which the previously discussed pulp dewatering clothing may be used. Pulp dewatering machine 40 includes in particular two such pulp-dewatering clothings 10, 10′. After turning around breast roll 42, clothing 10′ travels through pre-dewatering zone 44 in which liquid, more specifically water, is removed from pulp material Z which is placed on pulp dewatering clothing 10 by use of vacuum generating device 46 supported by gravity. During this process clothing 10 moves in the direction of arrow P through pre-dewatering zone 44. After pre-dewatering zone 44, clothings 10 and 10′ run together through a twin-wire or respectively twin-clothing zone 48, whereby the already pre-dewatered pulp material Z is positioned between clothings 10 and 10′. After turn roller 50, which essentially only redirects clothing 10, both clothing 10 and 10′ between which pulp material Z is located move first around a turn roller 52 whose roll turning axis A_l is located substantially above pre-dewatering zone 44. The angle of wrap at this turn roller 52 is almost 180°. Following turn roller 52 is an additional turn roller 54 with roll turning axis A₂ which is positioned above roll turning axis A₁ and around which clothing 10, and 10′ also wrap at an angle range of almost 180°.

Both, clothings 10 and 10′ of which at least one is arranged as previously described are accommodated in pulp dewatering machine 40 at a tension of approximately 3 to 100 kilonewtons per meter (kN/m), for example 8 to 80 kN/m, or 5 to 50 kN/m in the longitudinal direction of the clothing. Through this tension a comparatively strong pressure is exerted in the region of the two turn rollers 52, 54 onto pulp material Z disposed between clothing 10, 10′ so that, supported also by centrifugal force effect water is pressed or spun out of pulp material Z. Here, the two clothings 10, 10′ may be moved forward at a speed of approximately 50 to 500 meters per minute (m/min), 80 to 400 m/min, or 100 to 300 m/min.

With pulp dewatering machine 40 configured in this way, pulp material having a basis weight of approximately 400 to 2500 grams per meter squared (g/m²), 500 to 2000 g/m², or 800 to 1500 g/m² can be received and processed. It is of essential significance that in pulp dewatering machine 40, dewatering occurs without use of a press nip. An excellent dewatering capacity is achieved merely through the provision of a comparatively high tension of pulp dewatering clothings 10, 10′ in conjunction with redirecting same in twin-wire zone 48. Due to the omission of a press nip, in other words due to the longitudinal holding, for example between two rolls which are pressed against each other, the mechanical load on clothings 10, 10′ and thereby the threat of fibrillation is clearly reduced.

It must be pointed out that the dewatering characteristic in twin-wire zone 48 can be influenced by the arrangement of the two turn rollers 52, 54. It is possible, for example, to arrange them with a closed, grooved or drilled shell. It is also possible to vary the wrap angle, for example within the range of 120 to 210°. In an alternative pulp dewatering machine which is known from WO 2008/090052 the two dewatering rolls are not arranged above the pre-dewatering zone 44, but underneath same. This machine too, which can be equipped with at least one clothing according to the present invention works without a press nip and consequently with comparatively low mechanical load on the pulp dewatering clothing provided therein.

In conclusion it must be pointed out that fundamentally the inventive pulp dewatering clothings—in particular because of the floats on the machine-side, which protect the load absorbing longitudinal threads, and due to the improved load distribution can also be used in pulp dewatering machines which are equipped with a press nip. Herein it may for example be provided that the line press forces occurring in the press nip are in the range of approximately 5 to 1000 kN/m, 6 to 800 kN/m, or 10 to 600 kN/m.

While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

1. A pulp dewatering clothing for a pulp dewatering machine, the pulp dewatering clothing comprising:

a plurality of binding threads;

a pulp-side first woven fabric layer for receiving a cellulose pulp material to be dewatered, said pulp-side first woven fabric layer being formed with a plurality of first longitudinal threads which progress substantially in a longitudinal direction of the clothing and a plurality of first cross threads which progress substantially in a transverse direction of the clothing, wherein a plurality of first floats are formed by one of said first longitudinal threads and said first cross threads on a pulp-side outer side of the clothing; and

a machine-side second woven fabric layer formed with a plurality of second longitudinal threads which progress substantially in said longitudinal direction of the clothing and a plurality of second cross threads which progress substantially in said transverse direction of the clothing, said first woven fabric layer and said second woven fabric layer being joined to one another by said binding threads, wherein a plurality of second floats are formed by one of said second longitudinal threads or said second cross threads on a machine-side outer side of the clothing and at least one of a maximum float length and a mean float length of said second floats is greater than at least one of a maximum float length and a mean float length of said first floats.

2. The pulp dewatering clothing according to claim 1, wherein at least one of said second floats have a float length in a range of between approximately 2 and 11, and said first floats have a float length of a maximum of 4.

3. The pulp dewatering clothing according to claim 2, wherein said float length of said second floats is in a range of between approximately 3 to 9.

4. The pulp dewatering clothing according to claim 3, wherein said float length of said second floats is approximately 7.

5. The pulp dewatering clothing according to claim 1, wherein said first woven fabric layer is one of a plain weave fabric and a rib weave fabric.

6. The pulp dewatering clothing according to claim 1, wherein said longitudinal threads and said cross threads forming said first floats and said second floats have a thread type which is the same.

7. The pulp dewatering clothing according to claim 1, wherein said longitudinal threads and said cross threads forming said first floats and said second floats have a thread type which is the different.

8. The pulp dewatering clothing according to claim 1, wherein at least one of said first longitudinal threads and said binding threads progressing in said longitudinal direction in said first woven fabric layer are offset relative to at least one of said second longitudinal threads and said binding threads progressing in said transverse direction in said second woven fabric layer.

9. The pulp dewatering clothing according to claim 1, wherein one type of thread of said longitudinal threads and said cross threads is provided by warp threads and another type of threads of said longitudinal threads and said cross threads is provided by weft threads, said warp threads of said first woven fabric layer and said warp threads of said second fabric layer being offset relative to each other in a weft direction.

10. The pulp dewatering clothing according to claim 1, wherein said binding threads include binding thread pairs consisting always of two of said binding threads adjacently positioned and assigned to each other as pairs, said pairs continuing a weave structure of said first woven fabric layer.

11. The pulp dewatering clothing according to claim 1, said plurality of binding threads including binding threads not continuing a weave structure of said first woven fabric layer and not tying off with said first longitudinal threads or said first cross threads.

12. The pulp dewatering clothing according to claim 1, wherein the clothing is configured to handle a tension of approximately 3 to 100 kilonewtons per meter (kN/m)

13. The pulp dewatering clothing according to claim 12, wherein the clothing is configured to handle a tension of approximately 8 to 80 kN/m.

14. The pulp dewatering clothing according to claim 13, wherein the clothing is configured to handle a tension of approximately 5 to 50 kN/m.

15. A pulp dewatering machine, comprising:

at least one pulp dewatering clothing, comprising:

a plurality of binding threads;

a pulp-side first woven fabric layer for receiving a cellulose pulp material to be dewatered, said pulp-side first woven fabric layer being formed with a plurality of first longitudinal threads which progress substantially in a longitudinal direction of the clothing and a plurality of first cross threads which progress substantially in a transverse direction of the clothing, wherein a plurality of first floats are formed by one of said first longitudinal threads and said first cross threads on a pulp-side outer side of the clothing; and

a machine-side second woven fabric layer formed with a plurality of second longitudinal threads which progress substantially in said longitudinal direction of the clothing and a plurality of second cross threads which progress substantially in said transverse direction of the clothing, said first woven fabric layer and said second woven fabric layer being joined to one another by said binding threads, wherein a plurality of second floats are formed by one of said second longitudinal threads or said second cross threads on a machine-side outer side of the clothing and at least one of a maximum float length and a mean float length of said second floats is greater than at least one of a maximum float length and a mean float length of said first floats.

16. The pulp dewatering machine according to claim 15, said at least one pulp dewatering clothing being two pulp dewatering clothings guided around at least one turn roller in a twin-wire zone of the pulp dewatering machine.

17. The pulp dewatering machine according to claim 15, wherein the pulp dewatering machine is not equipped with a press nip.

18. The pulp dewatering machine according to claim 16, including a pre-dewatering zone located before said twin-wire zone and through which said pulp dewatering clothing is routed.

19. The pulp dewatering machine according to claim 18, wherein said at least one turn roller includes a first turn roller and an additional turn roller and in said twin-wire zone both of said two pulp dewatering clothings move first around said first turn roller having a first roll turning axis located substantially above said pre-dewatering zone, and subsequently move around said additional turn roller having another roll turning axis positioned above said first roll turning axis.

20. A method of using a pulp dewatering clothing, the method comprising the steps of:

providing at least one pulp dewatering clothing, comprising: a plurality of binding threads; a pulp-side first woven fabric layer for receiving a cellulose pulp material to be dewatered, said pulp-side first woven fabric layer being formed with a plurality of first longitudinal threads which progress substantially in a longitudinal direction of the clothing and a plurality of first cross threads which progress substantially in a transverse direction of the clothing, wherein a plurality of first floats are formed by one of said first longitudinal threads and said first cross threads on a pulp-side outer side of the clothing; and a machine-side second woven fabric layer formed with a plurality of second longitudinal threads which progress substantially in said longitudinal direction of the clothing and a plurality of second cross threads which progress substantially in said transverse direction of the clothing, said first woven fabric layer and said second woven fabric layer being joined to one another by said binding threads, wherein a plurality of second floats are formed by one of said second longitudinal threads or said second cross threads on a machine-side outer side of the clothing and at least one of a maximum float length and a mean float length of said second floats is greater than at least one of a maximum float length and a mean float length of said first floats; and

routing said at least one pulp dewatering clothing through a pre-dewatering zone located before a twin-wire zone in a pulp dewatering machine to dewater the pulp suspension with said at least one pulp dewatering clothing.