EP1754822A2 - Method for operating a pressing arrangement - Google Patents

Abstract

Operating a paper machine press arrangement with press nips (18, 22) through which the paper web passes together with a transfer belt (12) comprises selecting a peak pressure in the press nips of less than 10 MPa. Independent claims are also included for: (1) operating a paper machine press arrangement with press nips through which the paper web passes together with a transfer belt, comprising using a transfer belt with a Pusey-Jones hardness of 30 or less on the inside and outside under standard conditions when the belt is uncompressed; (2) operating a paper machine press arrangement with press nips through which the paper web passes together with a transfer belt, comprising using nip-forming rolls (14, 16, 20) covered with rubber, polyurethane or a similar soft material; (3) operating a paper machine press arrangement with press nips through which the paper web passes together with a transfer belt, comprising using nip-forming rolls with a cover thickness of 10-40 mm; (4) operating a paper machine press arrangement with press nips through which the paper web passes together with a transfer belt, comprising removing entained air and water from the inside of the transfer belt; (5) operating a paper machine press arrangement with press nips through which the paper web passes together with a transfer belt, comprising removing dirt from the inside and outside of the transfer belt.

Description

The invention relates to a method for operating a press arrangement serving to produce and / or treat a fibrous web, in particular paper or board web, with at least one press nip, through which the fibrous web is passed together with a transfer belt. It further relates to a corresponding operable press arrangement.

For pressing out water from fibrous webs, central roller press arrangements are frequently used.

In this case, the fibrous or paper web is transferred from a transfer belt or an at least substantially impermeable dewatering medium, for example a felt, to a smooth central roller. As far as in the following of an impermeable medium or volume is mentioned, this can basically still have a certain residual permeability. On the smooth central roller is a further pressing in an additional nip. An example of such a press is the so-called "DuoCentri II" press. This can also be provided with a shoe press nip as a preceding nip or as the last nip.

To remove the paper web in the subsequent drying section, a free train is required, in which the paper web is unsupported pulled by a covering medium on the drying wire. In such a free train, it often comes to a web break.

To avoid such web breaks already solutions have been specified in which the web is guided by an impermeable belt in the dryer section. In this case, the impermeable band, i. the so-called central band the central roller.

Since an absolute impermeability is not feasible in many cases, the band can, as already mentioned, also have a residual permeability.

With regard to the mechanical load, such impermeable belt or central belt as a result of combination loads of a shoe and a roll nip or two roll nips high demands arise. In particular, high peak pressures and high pressure gradients and, for shoe presses, high line loads and wide press zones are characteristic for roll nips.

The service life of a transfer belt or impermeable belt serving, for example, as a central belt depends essentially on the height of the peak pressure. In particular, roller presses have the property of producing extremely high peak pressures, since the pressing load is applied only to a small area. There is thus the risk of damage to the central belt. In any case, its life is significantly reduced. In the case of shorter central bands, the result is correspondingly shorter circulation times, so that the service life can definitely be regarded as critical, especially with a higher mechanical resistance. So far, no shorter belts were used in the production plants due to the high mechanical load and short running times. However, longer central belts now require a cellar guide and possibly a corresponding conversion of the press pulp, which involves considerable costs brings. In addition, such longer central belts lead to relatively high maintenance times for the band change. So far, central belts were used from a length of 20 to 25 m, and due to the required Kellerfilzführung always a corresponding conversion of the existing pulper was required. In systems with a central roller press and associated central belt so far central belts have been used, which at a web or machine speed of 900 m / min a belt length of about 14 m, at a machine speed of 1000 m / min a belt length of about 18 m and at a machine speed of 750 m / min partially also had a band length of 20.5 m. The number of cycles, ie the number of cycles of a respective central band during its run time is about 16 million cycles for a typical central or transfer belt. For the papermaker or operator of a paper machine, the relevant key figure is the running time in days. The usual systems require a value of 0.0155 or larger for the ratio transfer belt length / machine speed for a sufficient running time in days with a fixed number of cycles.

In practice, peak pressures can be determined by means of pressure-sensitive films which react with a color change corresponding to the respective pressure load (cf., for example, Fuji prescale film). With such films, the nip width and the peak pressure can be determined. Due to the compressibility of the material web in the nip, a surface pressure results from the theoretical line pressure (area = nip width x roll width). The peak pressure is measured at the point with the shortest distance of the press rolls. Another possibility known to a person skilled in the art for measuring the nip forces is the use of pressure-sensitive sensor films. The measurement data are generated by means of a computer evaluated and provide detailed values on the pressure curve in each nip.

The impermeable belts previously available on the market are used in paper machines in most cases in individual shoe press nips, where the mechanical stress of the tape is relatively low. In contrast, the life or number of cycles, i. greatly limits the number of passes of the belt during its travel time to the impermeable belts previously available on the market when used in a central roll press.

The aim of the invention is to provide an improved method and an improved press arrangement of the type mentioned, with which the mechanical stress of the transfer belt, in particular a short belt, which wraps around the central roller of a central roller press, in particular as so-called central belt, is lowered.

This object is achieved according to a first aspect of the invention in terms of the method in that the peak pressure is selected in the press nip <10 MPa.

Thus, the ratio transfer belt length (m) / web travel speed (m / min) <0.0155, in particular <0.014 and preferably <0.01 can be advantageously selected.

The peak pressure in the press nip is advantageously chosen to be <8 MPa and preferably <6 MPa. The press nip in question may be formed by a roll nip or by a shoe press nip.

The peak pressure occurs in the press nip at the point with the smallest possible spacing of the press rolls and can be measured by pressure-sensitive measuring sheets which function according to a chemical process or as sensors with measured data output.

For example, an at least substantially impermeable band can be used as the transfer band. In this case, such an impermeable tape may have a residual permeability.

If the transfer belt wraps around a central roller which forms two press nips with two press units, then according to a preferred practical embodiment of the method according to the invention the line load in the first press nip ≤ 100 kN / m provided in the web running direction is considered and / or the line load in the web running direction second provided on the central roll press nip in the case of a roll nip ≤ 120 kN / m and in the case of a shoe press nips ≤ 1000 kN / m is selected.

Due to this embodiment of the method can be achieved for the transfer belt or the central roller wrapping impermeable band without the use of a special tape a relatively long life or high life or number of cycles, ie high number of cycles of the tape during its term. This is achieved according to the present first aspect of the invention primarily by a corresponding reduction of the peak pressure. The dry content loss resulting from the corresponding relief of at least one respective nip provided on the central roll can be at least partially compensated for by corresponding increase of the line load in at least one other nip and / or a shoe nip provided on the central roll.

Thus, the load of the transfer belt is reduced in favor of the life or number of cycles. In practice, this brings considerable advantages not only in the use of a transfer belt offering a relatively lower mechanical resistance, but also in particular when using a transfer belt which offers a relatively higher mechanical resistance. In particular, shorter belts can now be used in which the service life is critical due to the shorter circulation times.

On account of the embodiment according to the invention, on the one hand, in general, an extension of the service life for any desired transfer belt and, on the other hand, an extension of the service life for relatively short transfer belts is achieved. Since the tape length alone is not meaningful, a key figure is introduced below, which also takes into account the different web running or machine speeds.

The use according to the invention of particularly relatively short central bands brings a number of advantages. Thus, in a press section with associated central roller and shorter central belt, among other things, considerable costs can be saved that the otherwise imperative cellar guide can be omitted. In addition, significantly shorter maintenance times result for the change of the central belt. If a central roll press is changed over to a driving mode with a central belt, then a shorter central belt loop also has the advantage that the conversion of the press pulper is eliminated. For example, an embodiment is conceivable in which the central belt only has a band length of about 15 m, eliminates the Kellerfilzführung and in particular, the existing pulper does not need to be rebuilt.

As already mentioned, the life of the transfer belt is defined by the number of cycles, ie the number of revolutions of the belt during its transit time. This number of cycles results from the following relationship: $$\mathrm{number\; of\; cycles}\left(\mathrm{\#}\right)\mathrm{=}\frac{\mathrm{machine\; speed}\mathrm{(}\mathrm{m}\mathrm{/}\min \mathrm{)}}{\mathrm{length}\left(\mathrm{m}\right)}\mathrm{\cdot }\mathrm{running\; time}\left(\mathrm{d}\right)$$

In particular, when using relatively shorter transfer belts is due to the higher number of cycles, i. The higher number of rounds of the band during its term to expect a lower duration in days than relatively longer bands at assumed same machine speed. Consequently, the tape length can be shorter on slower running machines than on faster machines, provided that the same running time measured in days is achieved.

The previously mentioned measure results from the following relationship: $$\mathrm{identification\; number}=\frac{\mathrm{length}\left(\mathrm{m}\right)}{\mathrm{machine\; speed}\mathrm{(}\mathrm{m}\mathrm{/}\min \mathrm{)}}$$

This measure is used to compare band lengths at different machine speeds. As can be seen from the relationship given above for the number of cycles, the number of cycles is inversely proportional to this figure. The following relationship applies: $$\mathrm{number\; of\; cycles}=\frac{\mathrm{running\; time}}{\mathrm{identification\; number}}$$

For the duration (d) the following results: $$\mathrm{running\; time}\left(\mathrm{d}\right)=\frac{\mathrm{length}\mathrm{\left(}\mathrm{m}\mathrm{\right)}}{\mathrm{machine\; speed}\mathrm{(}\mathrm{m}\mathrm{/}\min \mathrm{)}}\cdot \mathrm{Zykenzahl}\left(\#\right)$$

Due to the lower stress achieved according to the invention, the number of cycles, i. Number of rounds of the transfer belt increase during its term, and it is possible, e.g. a central band with a much smaller, defined by the ratio band length / machine speed characteristic at about the same, i. in particular to drive a slightly lower or slightly higher duration in days.

As already mentioned, this is not possible in the operation of the previously known typical machines in view of the relatively high mechanical loads occurring there. The ratio defined by the ratio band length / machine speed must be selected to be large in order to achieve a sufficient running time in days for a predeterminable number of cycles. The previously known systems need to achieve a sufficient duration in days at a fixed predetermined number of cycles defined by the ratio band length / machine speed index of 0.0155 or higher.

With the embodiment of the method according to the invention, there is an increase in transit time of the transfer belt, in particular an increase in transit time of a relatively shorter belt with a small characteristic defined by the belt length / machine speed ratio, where In particular, the transfer belt can be a central belt that wraps around the central roller of a central roller press.

As a counterpressure unit with which the central roller forms the first press nip provided on this central roller, in particular a suction press roller can be used.

This counterpressure unit, with which the central roller forms the first press nip provided on this central roller, is expediently assigned a further pressing unit in order to form a press nip preceding the two press nips on the central roller. This preceding press nip can be formed by a roll nip or by a shoe press nip.

The second press nip provided on the central roll may be formed by a roll nip or by a shoe press nip.

In the following, some preferred embodiments of the method according to the invention are indicated for the case in which both press nips provided on the central roll are each formed by a roll nip:

Thus, it is expedient to select the line load in the first press nip provided on the central roll ≦ 100 kN / m. In this case, the line load in this first press nip provided on the central roll is preferably selected to be ≦ 80 kN / m.

Alternatively or additionally, the line load in the second press nip provided on the central roll can be selected to be ≦ 120 kN / m. It is preferred the line load in this second provided on the central roller press nip ≤ 100 kN / m selected.

In order to at least substantially compensate for the loss of dry content resulting from the aforementioned relief, the line load in the press nip preceding the two press nips on the central roll is advantageously selected to be ≥70 kN / m in the case of a roll nip. In this case, the line load in this roll nip, which precedes the two press nips on the central roll, is preferably selected to be ≥ 90 kN / m.

In the event that the press nip preceding the two press nips at the central roll is formed by a shoe press nip, the line load in this preceding shoe press nip is advantageously chosen to be ≥ 120 kN / m and preferably ≥ 150 kN / m.

In the following, some preferred embodiments of the method according to the invention are indicated for the case that the press nip provided in the web running direction is formed by a nip and the second nip provided on the central roll is formed by a shoe press nip, ie the central roll to form the second press nip in particular, a shoe press unit is assigned, which may preferably be formed by a shoe press roll.

In this case, the line load in the roll nip provided on the central roll is advantageously selected to be ≦ 80 kN / m. In this case, the line load in this preceding roll nip is preferably selected to be ≦ 50 kN / m.

Alternatively or additionally, the line load in the shoe press nip provided on the central roller may advantageously be selected to be ≦ 1200 kN / m. In this case, the line load in this shoe press nip provided on the central roller is preferably selected to be ≦ 1000 kN / m.

To compensate for the loss of dry content resulting from this relief, the line load in the press nip preceding the two press nips on the central roll is advantageously selected to be ≥ 70 kN / m in the case of a roll nip. In this case, the line load is preferably chosen to be ≥ 90 kN / m in this roll nip preceding the two press nips on the central roll.

Alternatively or additionally, the line load in the shoe press nip provided on the central roller can advantageously be selected to be ≥ 800 kN / m. In this case, the line load in this shoe press nip provided on the central roller is preferably chosen to be ≥ 1000 kN / m.

Alternatively or additionally, the line load in the press nip preceding the two press nips on the central roll is expediently chosen to be ≥ 120 kN / m and preferably ≥ 150 kN / m in the case of a shoe press nip.

Alternatively or in addition to the solution variant according to the invention and in particular to the abovementioned line load combinations for the nips of the central roller press arrangement according to the invention, the hardness of the transfer belt ≦ 30 P & J in the uncontrolled belt state under standard conditions for the belt inner and band outside.

Alternatively or in addition to the above-mentioned inventive measures according to the invention, at least one of the respective Pressnip limiting roller with rubber or polyurethane or with a similar soft other material or plastic, respectively, to reduce the peak pressure accordingly. For the corresponding reduction of the peak pressure, the coverings of at least one press roll, at least one shoe press roll and / or the central roll can advantageously also be adapted.

Experiments have shown that with peak pressures above 10 MPa, the service life or running time of the belts decreases significantly. At a peak pressure of 8 MPa, 10 to 15 million nip passages are achievable. On the other hand, if 12 MPa and more are applied in a roll nip, the service life or running time is reduced. In roll nips, peak pressures of more than 20 MPa are achieved, depending on the press load and roller design. The service life or running time of a transfer belt is thereby reduced to a few days.

Advantageously, at least one roller of the press arrangement is covered with rubber or polyurethane or with a similar soft other plastic in order to reduce the peak pressure in a respective nip. Roller covers are already known which bring a certain reduction of the peak pressure with it.

Preferably, for a particular roll cover, a plastic having a hardness in a range of about 2 to about 90 P & J is selected. Particularly suitable and preferred is a respective roll cover made of a plastic having a hardness in a range of about 5 to about 40 P & J, wherein according to a preferred practical embodiment of the method according to the invention for a respective roll cover a plastic having a hardness in a range of about 7 to about 20 P & J is chosen.

Examples of cover qualities that meet these requirements include brands such as PolyDyne, Aqualis, G2000 as polyurethane or MagnaPress, and TopPress as rubber-based covers.

As a further alternative or additional measure for reducing the peak pressure, it is proposed according to the invention to select the thickness of the cover of at least one roller delimiting the respective press nip in a range from approximately 4 to approximately 50 mm. Particularly good results are achieved with a reference thickness in a range of about 10 to about 40 mm. In view of the particularly good results achieved, the thickness of a respective roll cover is preferably selected in a range of about 12 to about 30 mm.

It is also particularly advantageous if a respective roll cover, which preferably consists of incompressible plastic material, is additionally or alternatively provided with bores.

The incompressible plastic material can deform under pressure into these holes, so that the respective nip wider and the peak pressure is reduced accordingly.

In this case, at least some of the holes only partially penetrate the respective roll cover. In principle, however, it is also conceivable that at least part of the bores completely penetrate the respective roll cover, in which case an even softer nip is achieved.

Advantageously, the diameter of a respective bore is selected in a range of about 0.5 to about 10 mm. Preferably, the diameter of a respective bore is in a range of about 1.5 to about 8 mm, wherein the bore diameter according to a particularly advantageous Embodiment is selected in a range of about 2 to about 5 mm.

The holes are particularly advantageous when the open area of the respective roll cover is selected in a range of about 5 to about 40% of the roll surface. It is particularly advantageous if the open area of a respective roll cover lies in a range of about 20 to about 30% of the roll surface.

Alternatively or additionally, a respective roll cover, which preferably consists of incompressible plastic material, can also be provided with a crease to reduce the peak pressure on its surface.

Such a scoring of the plastic cover on the surface causes a widening of the respective press nips. The incompressible plastic material may expand under pressure into these grooves.

Advantageously, the groove width is selected in a range of about 0.2 to about 5 mm. Preferably, the groove width is in a range of about 0.4 to about 2 mm.

The land width between adjacent grooves is advantageously selected in a range of 0.5 to about 10 mm. Conveniently, the web width is in a range between about 1 to about 7 mm. It is particularly advantageous if the web width between adjacent grooves is selected in a range between about 1.5 to about 5 mm.

The ratio of land width to groove depth is advantageously selected in a range between about 0.2 to about 10. Of particular advantage in view of the softness and service life of the groove, a ratio of ridge width to groove depth in a range between about 0.5 to about 5. Preferably, the ratio of ridge width to groove depth in a range between about 0.8 to about 2 , 0 chosen.

Of particular advantage is when a respective roll cover is both drilled and grooved. The cover becomes even softer and the peak pressure is correspondingly lowered even further.

Of the two rolls forming a respective press nip, in each case only one or both rolls can be provided with a grooved and / or drilled roll cover. If both rolls of a respective press nips are each provided with a grooved or drilled roll cover, the result is a softer nip with lower peak pressures.

Advantageously, at least a portion of the respective roller cover completely penetrating holes simultaneously serves as suction holes.

After a convenient practical embodiment of the method according to the invention, the transfer belt is grooved. The transfer belt is softer. The nip width is increased and the peak pressure is lowered.

Conveniently, the groove depth ≤ 80% of the strip thickness is selected.

The thickness of the impermeable belt wrapping around the center roll is preferably in a range of about 1 to about 10 mm.

An optimal groove geometry is obtained when the ratio of land width to groove depth in a range for the grooved impermeable tape between about 0.5 and about 5 is selected. Preferably, this ratio of ridge width to groove depth is in a range between about 0.8 and about 2.

The roll diameter determines the achievable nip length. In order to keep the peak pressures low, preferably rollers with a respective diameter> 450 mm are used.

In the case where two press nips provided on a central roll are each formed by a roll nip, to reduce the peak pressure, the roll cover may be associated with the press roll associated with the central roll for forming the first roll nip provided at that central roll and / or the roll cover of the press roll , which is assigned to the central roller for forming the second roller nip provided on this central roller, and / or the roller cover of the central roller is designed or adapted accordingly.

To compensate for the loss of dry content resulting from the discharge in question, the line load in the press nip preceding the two press nips on the central roll is chosen to be ≥70 kN / m in the case of a roll nip, the line load being preferably ≥ 90 kN / m.

If the press nip preceding the two press nips on the central roll is formed by a shoe press nip, the line load in this nip press nip is advantageously chosen to be ≥120 kN / m, and preferably ≥150 kN / m.

In the case that the first press nip provided on the center roll is formed by a nip and the second nip provided on the center roll is formed by a shoe press nip, the reduction is made the peak pressure advantageously the roll cover of the press roll, which is associated with the central roll to form the first provided on this central roll press nips and / or the roll cover of the central roll executed or adapted accordingly.

The resulting dry content loss is advantageously at least partially compensated by the line load in the two press nips on the press nip preceding the central roll in the case of a roll nip ≥ 70 kN / m, preferably ≥ 90 kN / m and in the case of a shoe press nip advantageously ≥ 120 kN / m, preferably ≥ 150 kN / m is selected.

Alternatively or additionally, the line load in the second provided on the central roller, designed as a shoe press nip Pressnip ≥ 800 kN / m, preferably ≥ 1000 kN / m is suitably selected to compensate for the dry content loss.

According to a second aspect of the invention, said object with respect to the method is achieved by removing entrained air and water on the inside of the transfer belt, and / or by removing contaminants present on the inside and / or outside of the transfer belt.

According to this second aspect of the invention, a longer service life or transit time of the transfer belt or impermeable belt is thus achieved by measures of conditioning the impermeable belt.

Thus entrained air and water are removed on the inside of the belt in order to prevent floating of the transfer belt or of the central roller embracing impermeable belt and the transmission to ensure the drive power to non-driven rollers. Alternatively or additionally, it is advantageous if on the inside and on the outside of the transfer belt or impermeable belt existing contaminants are removed, for example as a result of residues of the fibrous web, since such contamination run along with the tape, between the press roller and the belt in the Nip and cause damage to the tape.

The removal of air and water or the removal of contaminants is preferably carried out by means of at least one scraper and / or at least one spray tube.

In principle, any combinations of the different embodiments of the two aspects of the invention are also possible.

The higher service life or running time of the transfer belt or the central roller encircling impermeable belt is thus achieved inter alia by the nip width and corresponding to the peak pressure in the press nip reducing design features of the press rolls or the stringing elements, the peak pressures in particular by a suitable choice of process parameters , in particular line loads, can be reduced.

The operation of a press arrangement with at least one of a transfer belt passed through press nip or a centered by a transfer belt or impermeable belt center roller can be done due to the inventive solutions thus without the use of special tapes with an acceptable service life or running time of the transfer belt or impermeable belt. The service life or running time of each transfer belt used is significantly increased, which is a more economical Operation in particular a respective central roller press assembly brings with it.

Further advantageous embodiments of the method according to the invention are specified in the subclaims.

The press arrangement advantageously operable according to the method of the invention comprises at least one press nip, through which the fibrous web is passed together with a transfer belt. In this case, the respective press nip can be formed either by a roller nip or a shoe press nip. The transfer belt is preferably formed by an at least substantially impermeable belt, wherein this impermeable belt can in principle have a residual permeability.

In a preferred practical embodiment of the press arrangement according to the invention, the transfer belt wraps around a central roll, which form two press nips with two counterpressure units, wherein as a counterpressure unit with which the central roll forms the first press nip provided on this central roll, preferably a suction press roll is provided and / or the counterpressure unit the central roller forms the first press nip provided on this central roller, preferably a further press unit is assigned to form a press nip preceding the two press nips on the central roller.

In this case, the press nip preceding the two press nips on the central roll can be formed by a nip or by a nip.

The counterpressure unit, with which the central roller forms the first press nip provided on this central roller, can therefore be associated, in particular, as a further press unit, with a shoe press unit, wherein this shoe press unit is preferably formed by a shoe press roller.

For example, both press nips provided on the central roll can each be formed by a roll nip, or the press nip provided on the central roll in the web running direction can be formed by a nip and the second press nip provided on the central roll can be formed by a nip. In the latter case, the central roller may thus be associated with a shoe press unit, which is preferably formed by a shoe press roll.

According to a preferred practical embodiment of the press arrangement according to the invention, the hardness of the transfer belt is ≤ 30 P & J in the uncompressed belt state under standard conditions for the inside and outside of the belt.

Advantageously, at least one roll is covered with rubber or polyurethane or with a similar soft other material or plastic.

In this case, a respective roll cover is advantageously made of a plastic having a hardness in a range of about 2 to about 90 P & J, preferably having a hardness in a range of about 5 to about 40 P & J and preferably having a hardness in a range of about 7 to about 20 P & J.

It is also advantageous if the thickness of a respective roll cover in a range of about 4 to about 50 mm, in particular in one area from about 10 to about 40 mm, and preferably within a range of from about 12 to about 30 mm.

A respective roll cover, which preferably consists of incompressible plastic material, can in particular also be provided with bores. These holes can only partially or completely penetrate the respective roll cover.

The diameter of a respective bore is advantageously in a range of about 0.5 to about 10 mm, in particular in a range of about 1.5 to about 8 mm, and preferably in a range of about 2 to about 5 mm.

These bores prove particularly advantageous in the case of an open area of a respective roll cover in a range of about 5 to about 40% of the roll surface, and preferably in a range of about 20 to about 30% of the roll surface.

Alternatively or additionally, a respective roll cover, which preferably consists of incompressible plastic material, may also be provided with a scoring on its surface. The groove width is expediently in a range of about 0.2 to about 5 mm, and preferably in a range of about 0.4 to about 2 mm.

The web width between adjacent grooves is advantageously in a range between about 0.5 to about 10 mm, in particular in a range between about 1 to about 7 mm, and preferably in a range between about 1.5 to about 5 mm.

The ratio of web width to groove depth is advantageously in a range between about 0.2 to about 10, in particular in a range between about 0.5 to about 5, and preferably in a range between about 0.8 to about 2.0.

According to an expedient practical embodiment of the press arrangement according to the invention, a respective roll cover is both drilled and grooved.

Of the two rolls forming a respective press nip, only one or even both rolls can be provided with a grooved or drilled roll cover.

At least part of the respective roller cover completely penetrating bore can serve as suction holes at the same time.

Of particular advantage is also when the transfer belt is grooved. The scoring is preferably provided on the inside of the transfer belt.

The groove depth is preferably ≤ 80% of the strip thickness.

The thickness of the transfer belt or impermeable belt is advantageously in a range of about 1 to about 10 mm.

Advantageously, for the grooved transfer belt, the ratio of land width to groove depth is in a range between about 0.5 and about 5, and preferably in a range of about 0.8 and about 2.

The rollers are preferably provided with a respective diameter> 450 mm.

If both press nips provided on the central roll are each formed by a roll nip, then advantageously the roll cover of the press roll which is assigned to the central roll for forming the first roll nip provided on this central roll and / or the roll cover of the press roll which forms the central roll to form the first roll nip is associated with the second provided at this central roller roller nips and / or the roller cover of the central roller executed or adapted accordingly.

If the first press nip provided on the central roll is formed by a roll nip and the second press nip provided on the central roll is formed by a shoe press nip, then advantageously the roll cover of the press roll is associated with the central roll to form the first press nip provided on this central roll and / or Roller cover of the central roller designed or adapted accordingly.

According to a preferred practical embodiment of the press arrangement according to the invention at least one scraper and / or at least one spray tube is provided to remove entrained on the inside of the transfer belt air and water and / or on the inside and on the outside of the impermeable belt existing contaminants.

The following table shows purely by way of example results of attempts to influence the peak pressures in a press nip formed between two rolls (roll 1, roll 2) by suitable choice of parameters. <U> Table </ u> Roller 1 ∅ Hardness P & J Line load kN / m Roller 2 0 Hardness P & J Groove depth mm RATIOS. Steg / RT reference thickness Peak pressure MPa Nip width mm Comparison: Influence diameter, smooth steel rollers, felt weight 1600 g / m ² 1300 0 130 795 0 - - 14 26 1300 0 130 1200 0 - - 8th 44 Influence reference hardness, standard groove: web 2 mm groove width 0.8 mm; Groove depth 2 mm, felt 1400 g / m ² 1440 5 180 875 0 2 1 15 30 1440 10 180 875 0 2 1 13 32 1440 15 180 875 0 2 1 11 34 Influence of line load; Standard groove: bridge 2 mm groove width 0.8 mm; Groove depth 2 mm; Felt 1200 g / m ² 1200 0 100 420 4 2 1 10 28 1200 0 140 420 4 2 1 13 30 Influence reference thickness; Standard groove: bridge 2 mm groove width 0.8 mm; Groove depth 2 mm; Felt 1600 g / m ² 1290 10 90 1400 0 2 1 8th 5.5 38 1290 10 90 1400 0 2 1 21 4.0 42

The sole figure of the drawing shows a schematic representation of an exemplary embodiment of a press arrangement 10 for the treatment of a fibrous web, which may be in particular a paper, board or tissue web. The press arrangement 10 can therefore be part of a paper machine, in particular. It can be operated in particular according to the method according to the invention.

As can be seen with reference to FIG. 1, the press arrangement 10 comprises a central roller 14 looped by a transfer belt, here for example an at least substantially impermeable belt 12, which has a suction press roller 16, a first press nip 18 provided on this central roller 14 and a shoe press unit , here a shoe press roll 20, a second press nip 22 provided on this central roll 14 forms. The Saugpresswalze 16 and the shoe press roll 20 thus serve each as a counter-press unit to the central roller 14 to the two in the web running direction L consecutive, provided on the central roller 14 Press nips 18 and 22 to form. The impermeable tape 12 may have residual permeability.

The suction press roll 16 is a further press unit, here a shoe press unit such as in particular a shoe press roll 24, assigned to form a press nip 26 preceding the two press nips 18, 22 on the central roll 14.

Around the suction press roll 16 is a circulating belt 28, e.g. a felt, led by the fibrous web was previously taken over by a wire 30 of a former 32. To assist the transfer in question, the air-permeable belt 28 is guided in the transition region around an evacuated guide roller 34.

To the shoe press roll 24 is another circulating belt 36, for example, again a felt out. The preceding press nip 26 can therefore be double felted in particular.

Subsequent to the preceding press nip 26, the fibrous web, together with the band 28, is guided further around the suction press roll 16 and subsequently into the first press nip 18 provided on the central roll 14, in the region of which it is taken over by the impermeable strip 12 wrapping around the central roll 14.

Subsequent to the first press nip 18 provided on the central roll 14, the fibrous web, together with the impermeable belt 12, is guided further around the central roll 14 into the second press nip 22 provided on this central roll 14, which, in the present case, is the same as the preceding press nip 26 Schuhpressnip is executed.

In contrast, a roll nip is formed between the suction press roll 16 and the central roll 14.

The shoe press roll 20 associated with the central roll 14 is also recessed from a circulating belt 38, e.g. a felt, entwined.

Following the second press nip 22 provided on the central roll 14, here shoe press nip, the fibrous material is e.g. taken over by a drying wire 40 a drying section 42 of the impermeable tape 12, wherein the drying wire 40 is guided in the transfer area to a sucked guide roller 44.

With the drying wire 40, the fibrous web is then fed, for example, to a first drying cylinder 46 of the drying section 42. In principle, however, the fibrous web can also be transferred to another unit, e.g. a smoothing device, the paper machine are passed.

In the present case, therefore, as viewed in the web running direction L first provided on the central roller 14 nip 18 is formed by a roller nip and the second provided on the central roller 14 press nip 22 by a shoe press nip.

To increase the service life or running time of the impermeable belt 12, the previously described measures for reducing the peak pressure and / or the conditioning measures described above can now be applied correspondingly.

LIST OF REFERENCE NUMBERS

10

Press arrangement

12

Transfer tape, impermeable tape

14

central roll

16

suction press

18

first press nip

20

Shoe press roll

22

second press nip

24

Shoe press roll

26

previous press nip

28

circumferential band, felt

30

screen belt

32

molder

34

suctioned guide roller

36

circumferential band, felt

38

circumferential band, felt

40

dryer

42

drying section

44

suctioned guide roller

46

drying cylinders

L

Web direction

Claims (176)

Method for operating a press arrangement (10) serving to produce and / or treating a fibrous web, in particular a paper or board web, with at least one press nip (18, 22) through which the fibrous web is passed together with a transfer belt (12),
characterized,
that the peak pressure (P _max) in the press nip (18, 22) <10 MPa is chosen. Method according to claim 1,
characterized,
that the ratio of transfer tape length (m) / web speed (m / min) <0.0155, in particular <0.014 and preferably <0.01 is chosen. Method according to claim 1 or 2,
characterized,
that the peak pressure (22 18) <8 MPa and preferably <6 MPa is chosen (P _max) in the press nip. Method according to one of the preceding claims,
characterized,
in that at least one press nip (18) is formed by a roller nip. Method according to one of the preceding claims,
characterized,
in that at least one press nip (22) is formed by a shoe press nip. Method according to one of the preceding claims,
characterized,
in that an at least substantially impermeable belt is used as the transfer belt (12). Method according to claim 6,
characterized
in that the at least substantially impermeable band has a residual permeability. Method according to one of the preceding claims,
characterized,
in that the transfer belt (12) encloses a central roller (14) which forms two press nips (18, 22) with two counterpressure units (16, 20). Method according to claim 8,
characterized,
that the line load considered in the web running direction (L) first on the central roll (14) provided for the press nip (18) ≤ 100 kN / m and / or the linear load in the direction of web travel (L) of the second of the central roll (14) provided for the press nip (22 ) in the case of a roll nip ≤ 120 kN / m and in the case of a shoe press nip ≤ 1000 kN / m is selected. Method according to claim 8 or 9,
characterized,
in that a suction press roll (16) is used as the counterpressure unit, with which the central roll (14) forms the first press nip (18) provided on this central roll. Method according to one of the preceding claims,
characterized,
in that the counterpressure unit (16), with which the central roller (14) forms the first press nip (18) provided on this central roller (14), is associated with a further press unit (24) in order to apply a press nip (18, 22) to the press nip (18, 22) Central roller (14) preceding press nip (26) to form. Method according to claim 11,
characterized,
in that the press nip (26) which precedes the two press nips (18, 22) on the central roll (14) is formed by a roll nip. Method according to claim 11,
characterized,
in that the press nip (26) preceding the two press nips (18, 22) on the central roll (14) is formed by a shoe press nip. Method according to claim 13,
characterized,
in that the counterpressure unit (16), with which the central roller (14) forms the first press nip (18) provided on this central roller (14), is assigned, as a further press unit, a shoe press unit (24). Method according to claim 14,
characterized,
in that a shoe press roll (24) is used as the shoe press unit. Method according to one of the preceding claims,
characterized,
in that the two press nips (18, 22) provided on the central roller (14) are each formed by a roller nip. Method according to claim 16,
characterized,
that the line load provided in the first of the central roll (14) press nip (18) ≤ 100 kN / m is chosen. Method according to claim 17,
characterized,
that the line load provided in the first of the central roll (14) press nip (18) ≤ 80 kN / m is chosen. Method according to one of claims 16 to 18,
characterized,
that the line load provided in the second of the central roll (14) press nip (22) ≤ 120 kN / m is chosen. Method according to claim 19,
characterized,
that the line load provided in the second of the central roll (14) press nip (22) ≤ 100 kN / m is chosen. Method according to one of claims 16 to 20,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of nip rollers kN / m is chosen ≥ 70th Method according to claim 21,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of nip rollers kN / m is chosen ≥ 90th Method according to one of claims 16 to 20,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of a Schuhpressnips kN / m is chosen ≥ 120th Method according to claim 23,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of a Schuhpressnips kN / m is chosen ≥ 150th Method according to one of claims 1 to 15,
characterized,
in that the press nip (18) provided on the central roller (14) in the web running direction (L) is provided by a roller nip and the nip second press nip (22) provided on the central roll (14) is formed by a shoe press nip. Method according to claim 25,
characterized,
in that the central roller (14) is associated, for forming the shoe press nip (22), with a shoe press unit, which is preferably formed by a shoe press roll (20). A method according to claim 25 or 26,
characterized,
that the line load provided in at the central roller (14) roll nip (18) ≤ 80 kN / m is chosen. Method according to claim 27,
characterized,
that the line load provided in at the central roller (14) roll nip (18) ≤ 50 kN / m is chosen. Method according to one of claims 25 to 28,
characterized,
that the line load provided in at the central roll (14) shoe press nip (22) ≤ 1,200 kN / m is chosen. Method according to claim 29,
characterized,
that the line load provided in at the central roll (14) shoe press nip (22) ≤ 1000 kN / m is chosen. Method according to one of claims 25 to 30,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of nip rollers kN / m is chosen ≥ 70th Method according to claim 31,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of nip rollers kN / m is chosen ≥ 90th Method according to one of claims 25 to 32,
characterized,
that the line load provided in at the central roll (14) shoe press nip (22) ≥ 800 kN / m is chosen. Method according to claim 33,
characterized,
that the line load provided in at the central roll (14) shoe press nip (22) ≥ 1000 kN / m is chosen. Method according to one of claims 25 to 34,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of a Schuhpressnips kN / m is chosen ≥120. Method according to claim 35,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of a Schuhpressnips kN / m is chosen ≥ 150th Method for operating a press arrangement (10) serving to produce and / or treat a fibrous web, in particular a paper or board web, with at least one press nip (18, 22), through which the fibrous web is passed together with a transfer belt (12), in particular one of the preceding claims,
characterized,
that the hardness of the transfer belt (12) ≦ 30 P & J in the uncompressed belt state under standard conditions for the inside and outside of the belt is selected. Method according to claim 37,
characterized,
that the ratio of transfer tape length (m) / web speed (m / min) <0.0155, in particular <0.014 and preferably <0.01 is chosen. Method according to claim 37 or 38,
characterized,
in that at least one press nip (18) is formed by a roller nip. Method according to one of claims 37 or 39,
characterized,
in that at least one press nip (22) is formed by a shoe press nip. Method according to one of claims 37 to 40,
characterized,
in that an at least substantially impermeable belt is used as the transfer belt (12). Method according to claim 41,
characterized,
in that the at least substantially impermeable band has a residual permeability. Method according to one of claims 37 to 42,
characterized,
in that the transfer belt (12) wraps around a central roller (14) which forms two press nips (18, 22) with two counterpressure units (16, 22). Method for operating a press arrangement (10) serving to produce and / or treating a fibrous web, in particular paper or board web, with at least one press nip (18, 22) through which the fibrous web is passed with a transfer belt (12), in particular one of the preceding claims,
characterized,
in that at least one roller (14, 16, 20) delimiting the press nip (18, 22) is covered with rubber or polyurethane or with a similar soft other material or plastic. A method according to claim 44,
characterized,
that the ratio of transfer tape length (m) / web speed (m / min) <0.0155, in particular <0.014 and preferably <0.01 is chosen. Method according to claim 44 or 45,
characterized,
in that at least one press nip (18) is formed by a roller nip. Method according to one of claims 44 to 46,
characterized,
in that at least one press nip (22) is formed by a shoe press nip. Method according to one of claims 44 to 47,
characterized,
in that an at least substantially impermeable belt is used as the transfer belt (12). Method according to claim 48,
characterized,
in that the at least substantially impermeable band has a residual permeability. Method according to one of claims 44 to 49,
characterized,
in that the transfer belt (12) wraps around a central roller (14) which forms two press nips (18, 22) with two counterpressure units (16, 20), the counterpressure unit (16) with which the central roller (14) is the first at this central roller (14) provided press nip (18), preferably a further pressing unit (24) is assigned to form a two nips (18, 22) on the central roller (14) preceding nip (26), as a pressing unit (16, 20, 24) each used a press roll or a shoe press roll and at least one of the rollers (14, 16, 20, 24) is covered with rubber or polyurethane or with a similarly soft other material or plastic. Method according to one of claims 44 to 50,
characterized,
that for a respective roll cover, a plastic having a hardness in a range of about 2 to about 90 P & J is selected. Method according to claim 51,
characterized,
that for a respective roll cover, a plastic having a hardness in a range of about 5 to about 40 P & J is selected. Method according to claim 52,
characterized,
that for a respective roll cover, a plastic having a hardness in a range of about 7 to about 20 P & J is selected. Method for operating a press arrangement (10) serving to produce and / or treating a fibrous web, in particular paper or board web, with at least one press nip (18, 22) through which the fibrous web is passed with a transfer belt (12), in particular one of the preceding claims,
characterized,
in that the thickness of the cover of at least one roller (14, 16, 20) bounding the press nip (18, 22) is selected within a range of approximately 10 to approximately 40 mm. Method according to claim 54,
characterized,
that the ratio of transfer tape length (m) / web speed (m / min) <0.0155, in particular <0.014 and preferably <0.01 is chosen. Method according to claim 54 or 55,
characterized,
in that at least one press nip (18) is formed by a roller nip. Method according to one of claims 54 to 56,
characterized,
in that at least one press nip (22) is formed by a shoe press nip. Method according to one of claims 54 to 57,
characterized,
in that an at least substantially impermeable belt is used as the transfer belt (12). Method according to claim 58,
characterized,
in that the at least substantially impermeable band has a residual permeability. Method according to one of claims 54 to 59,
characterized,
in that the transfer belt (12) wraps around a central roller (14) which forms two press nips (18, 22) with two counterpressure units (16, 20), the counterpressure unit (16) with which the central roller (14) is the first at this central roller (14) provided press nip (18), preferably a further pressing unit (24) is associated to form a two nips (18, 22) on the central roller (14) preceding the press nip (26) as a pressing unit (16, 20 , 24) each a press roll or a shoe press roll is used, and the thickness of at least one roll cover is selected in a range of about 4 to about 50 mm. Method according to one of claims 54 to 60,
characterized,
that the thickness of a respective roll cover is selected in a range of about 10 to about 40 mm. Method according to claim 61,
characterized,
that the thickness of a respective roll cover is selected in a range of about 12 to about 30 mm. Method according to one of claims 44 to 62,
characterized,
in that a respective roll cover, which preferably consists of incompressible plastic material, is provided with bores. Method according to claim 63,
characterized,
that at least a portion of the holes penetrates the respective roller cover only partially. Method according to claim 63 or 64,
characterized,
that at least some of the holes completely penetrate the respective roll cover. Method according to one of claims 63 to 65,
characterized,
that the diameter of a respective bore is selected in a range of about 0.5 to about 10 mm. Method according to claim 66,
characterized,
that the diameter of a respective bore is selected in a range of about 1.5 to about 8 mm. Method according to claim 67,
characterized,
that the diameter of a respective bore is selected in a range of about 2 to about 5 mm. Method according to one of claims 63 to 68,
characterized,
that the open surface of a respective roll cover is selected in a range from about 5 to about 40% of the roll surface. Method according to claim 69,
characterized,
that the open surface of a respective roll cover is selected in a range of about 20 to about 30% of the roll surface. Method according to one of claims 44 to 70,
characterized,
in that a respective roll cover, which preferably consists of incompressible plastic material, is provided with a scoring on its surface. Method according to claim 71,
characterized,
that the groove width is selected in a range from about 0.2 to about 5 mm. Method according to claim 72,
characterized,
that the groove width is selected in a range from about 0.4 to about 2 mm. Method according to one of claims 71 to 73,
characterized,
that the land width between adjacent grooves in a range between about 0.5 to about 10 mm is chosen. Method according to claim 74,
characterized,
that the land width between adjacent grooves in a range between about 1 to about 7 mm is selected. Method according to claim 75,
characterized,
that the land width between adjacent grooves in a range between about 1.5 to about 5 mm is selected. Method according to one of claims 71 to 76,
characterized,
that the ratio of ridge width is selected to the groove depth in a range between about 0.2 to about 10 degrees. Method according to claim 77,
characterized,
that the ratio of ridge width is selected to the groove depth in a range between about 0.5 to about. 5 Method according to claim 78,
characterized,
that the ratio of ridge width is selected to the groove depth in a range between about 0.8 to about 2.0. Method according to one of claims 63 to 79,
characterized,
that a respective roll cover is both drilled and grooved. Method according to one of claims 63 to 80,
characterized,
in that at least one press nip (18, 22, 26) is formed between rolls, of which only one is provided with a grooved or drilled roll cover. Method according to one of claims 63 to 81,
characterized,
in that at least one press nip (16, 18, 26) is formed between rollers, both of which are respectively grooved and bored. Method according to one of claims 63 to 82,
characterized,
that at least a portion of the respective roller cover completely penetrating holes simultaneously serves as suction holes. Method according to one of the preceding claims,
characterized,
that the transfer belt (12) is grooved. Method according to claim 84,
characterized,
that the scoring is provided on the inside of the transfer belt (12). Method according to claim 84 or 85,
characterized,
that the groove depth ≤ 80% of the strip thickness is selected. Method according to one of the preceding claims,
characterized,
that the thickness of the transfer belt (12) is selected in a range of about 1 to about 10 mm. Method according to one of claims 84 to 87,
characterized,
that the grooved transfer belt (12) is selected, the ratio of web width to the groove depth in a range between about 0.5 and about. 5 Method according to claim 88,
characterized,
that the ratio of ridge width is selected to the groove depth in a range between about 0.8 and about. 2 Method according to one of the preceding claims,
characterized,
that rollers (14, 16, 24) are used with a respective diameter> 450 mm. Method according to one of claims 44 to 90,
characterized,
in that both press nips (18, 22) provided on the central roll (14) are each formed by a roll nip and that the roll cover at least of the press roll (16), that of the central roll (14) to form the first roll nip provided on this central roll (14) (18) is assigned, is carried out accordingly. Method according to one of claims 44 to 91,
characterized,
in that both press nips (18, 22) provided on the central roll (14) are each formed by a roll nip, and in that the roll cover at least of the press roll, that of the central roll (14) to form the second roll nip (22) provided on this central roll (14). is assigned, is carried out accordingly. Method according to one of claims 44 to 92,
characterized,
in that both press nips (18, 22) provided on the central roll (14) are each formed by a roll nip and that the roll cover at least of the central roll (14) is designed accordingly. Method according to one of claims 91 to 93,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of nip rollers kN / m is chosen ≥ 70th Method according to claim 94,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of nip rollers kN / m is chosen ≥ 90th Method according to one of claims 91 to 93,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of a Schuhpressnips kN / m is chosen ≥ 120th Method according to claim 96,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of a Schuhpressnips kN / m is chosen ≥ 150th Method according to one of claims 44 to 90,
characterized,
in that the first press nip (18) provided on the central roll (14) is formed by a nip and the second press nip (22) provided on the central roll (14) is formed by a shoe press nip and in that the roll cover is at least the press roll (16), that of the central roll (14) is associated with the formation of the first at this central roller (14) provided Pressnips (18) is carried out accordingly. Method according to one of claims 44 to 90 and 98,
characterized,
in that the first press nip (18) provided on the central roll (14) is formed by a nip and the second press nip (22) provided on the central roll (14) is formed by a shoe press nip and in that the roll cover is carried out correspondingly at least to the central roll (14). A method according to claim 98 or 99,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of nip rollers kN / m is chosen ≥ 70th Method according to claim 100,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of nip rollers kN / m is chosen ≥ 90th Method according to one of claims 98 to 101,
characterized,
that the line load provided in the second of the central roll (14), designed as a shoe press nip press nip (22) ≥ 800 kN / m is chosen. Method according to claim 102,
characterized,
that the line load provided in the second of the central roll (14), designed as a shoe press nip press nip (22) ≥ 1000 kN / m is chosen. Method according to one of claims 98 to 103,
characterized in that
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of a Schuhpressnips kN / m is chosen ≥ 120th Method according to claim 104,
characterized,
that the line load in the two press nips (18, 22) on the central roll (14) preceding the press nip (26) in the case of a Schuhpressnips kN / m is chosen ≥ 150th Method for operating a press arrangement (10) serving to produce and / or treating a fibrous web, in particular paper or board web, with at least one press nip (18, 22) through which the fibrous web is passed with a transfer belt (12), in particular one of the preceding claims,
characterized,
that on the inside of the transfer belt (12) entrained air and water are removed. Method according to claim 106,
characterized,
that the ratio of transfer tape length (m) / web speed (m / min) <0.0155, in particular <0.014 and preferably <0.01 is chosen. Method according to claim 106 or 107,
characterized,
in that at least one press nip (18) is formed by a roller nip. Method according to one of claims 106 to 108,
characterized,
in that at least one press nip (22) is formed by a shoe press nip. Method according to one of Claims 106 to 109,
characterized,
in that an at least substantially impermeable belt is used as the transfer belt (12). Method according to claim 110,
characterized,
in that the at least substantially impermeable band has a residual permeability. Method according to one of claims 106 to 111,
characterized,
in that the transfer belt (12) wraps around a central roller (14) which forms two press nips (18, 22) with two counterpressure units (16, 20). Method for operating a press arrangement (10) serving to produce and / or treating a fibrous web, in particular paper or board web, with at least one press nip (18, 22) through which the fibrous web is passed with a transfer belt (12), in particular one of the preceding claims,
characterized,
that on the inside and on the outside of the transfer belt (12) existing contaminants are removed. Method according to claim 113,
characterized,
that the ratio of transfer tape length (m) / the web running speed (m / min) <0.0155, especially <than 0.014 and preferably <0.01 as selected. Method according to claim 113 or 114,
characterized,
in that at least one press nip (18) is formed by a roller nip. Method according to one of claims 113 to 115,
characterized,
in that at least one press nip (22) is formed by a shoe press nip. Method according to one of claims 113 to 116,
characterized,
in that an at least substantially impermeable belt is used as the transfer belt (12). Method according to claim 117,
characterized,
in that the at least substantially impermeable band has a residual permeability. Method according to one of claims 113 to 118,
characterized,
in that the transfer belt (12) wraps around a central roller (14) which forms two press nips (18, 22) with two counterpressure units (16, 20). Method according to one of claims 113 to 119,
characterized,
in that the removal of air and water or the removal of soiling is effected by means of at least one scraper and / or at least one spray tube. Press arrangement (10) for producing and / or treating a fibrous web, in particular paper or board web, with at least one press nip (18, 22), through which the fibrous web is passed together with a transfer belt (12), in particular operable according to the method of one of the preceding claims. Method according to claim 121,
characterized,
that the ratio of transfer tape length (m) / web speed (m / min) <0.0155, in particular <0.014 and preferably <0.01 is chosen. Press arrangement according to claim 121 or 122,
characterized,
in that at least one press nip (18) is formed by a roller nip. Press arrangement according to one of claims 121 to 123,
characterized,
in that at least one press nip (22) is formed by a shoe press nip. Press arrangement according to one of claims 121 to 124,
characterized,
that the transfer belt (12) is formed by an at least substantially impermeable belt. Press arrangement according to claim 125,
characterized,
in that the at least substantially impermeable band has a residual permeability. Press arrangement according to one of claims 121 to 126,
characterized,
that the transfer belt (12) wrapped around a central roller (14) with two counter-pressing units (16, 20) comprises two press nips (18, 22), wherein as a counterpressure unit (16) with which the central roller (14) forms the first press nip (18) provided on this central roller (14), preferably a suction press roll is provided and / or the counterpressure unit (16) with which the central roller (14) engages first press nip (18) provided on this central roller (14), preferably associated with a further press unit (24), in order to form a press nip (26) preceding the two press nips (18, 22) on the central roller (14). Press arrangement according to claim 127,
characterized,
in that the press nip (26) preceding the two press nips (18, 22) on the central roll (14) is formed by a roll nip. Press arrangement according to claim 128,
characterized,
in that the press nip (26) preceding the two press nips (18, 22) on the central roll (14) is formed by a shoe press nip. Press arrangement according to claim 129,
characterized,
in that the counterpressure unit (16) with which the central roller (14) forms the first press nip (18) provided on this central roller (14) is associated with a shoe press unit (24) as the further press unit. Press arrangement according to claim 130,
characterized,
in that a shoe press roll is provided as the shoe press unit (24). Press arrangement according to one of the preceding claims,
characterized,
in that the two press nips (18, 22) provided on the central roll (14) are each formed by a roll nip. Press order according to one of claims 121 to 131,
characterized,
in that the press nip (18) provided on the central roller (14) in the web running direction (L) is formed by a roller nip and the second press nip (22) provided on the central roller (14) is formed by a shoe press nip. Press arrangement according to claim 133,
characterized,
in that the central roller (14) for forming the shoe press nip (22) is associated with a shoe press unit, which is preferably formed by a shoe press roll (20). Press arrangement according to one of the preceding claims,
characterized,
in that the hardness of the transfer belt (12) is ≦ 30 P & J in the uncompressed belt state under standard conditions for the inside and outside of the belt. Press arrangement according to one of the preceding claims,
characterized,
in that at least one roller (14, 16, 24) is covered with rubber or polyurethane or with a similarly soft other material or plastic. Press arrangement according to claim 136,
characterized,
that a respective roll cover consists of a plastic having a hardness in a range of about 2 to about 90 P & J. Press arrangement according to claim 137,
characterized,
that a respective roll cover consists of a plastic with a hardness in a range from about 5 to about 40 P & J. Press arrangement according to claim 138,
characterized,
that a respective roll cover consists of a plastic with a hardness in a range from about 7 to about 20 P & J. Press arrangement according to one of the preceding claims,
characterized,
that the thickness of each roll cover is in a range of about 4 to about 50 mm. Press arrangement according to claim 140,
characterized,
that the thickness of a respective roll cover is in a range of about 10 to about 40 mm. Press arrangement according to claim 141,
characterized,
that the thickness of each roll cover is in a range of about 12 to about 30 mm. Press arrangement according to one of claims 136 to 142,
characterized,
in that a respective roll cover, which preferably consists of incompressible plastic material, is provided with bores. Press arrangement according to claim 143,
characterized,
that at least a portion of the holes penetrates the respective roller cover only partially. Press arrangement according to claim 143 or 144,
characterized,
that at least some of the holes completely penetrate the respective roll cover. Press arrangement according to one of claims 143 to 145,
characterized,
that the diameter of a respective bore is in a range of about 0.5 to about 10 mm. Press arrangement according to claim 146,
characterized,
that the diameter of a respective bore is in a range of about 1.5 to about 8 mm. Press arrangement according to claim 147,
characterized,
that the diameter of a respective bore is in a range of about 2 to about 5 mm. Press arrangement according to one of claims 143 to 148,
characterized,
that the open surface of a respective roll cover is in a range of about 5 to about 40% of the roll surface. Press arrangement according to claim 149,
characterized,
that the open surface of a respective roll cover is in a range of about 20 to about 30% of the roll surface. Press arrangement according to one of claims 136 to 150,
characterized,
in that a respective roll cover, which preferably consists of incompressible plastic material, is provided with a scoring on its surface. Press arrangement according to claim 151,
characterized,
that the groove width is in a range of about 0.2 to about 5 mm. Press arrangement according to claim 152,
characterized,
that the groove width is in a range of about 0.4 to about 2 mm. Press arrangement according to one of claims 151 to 153,
characterized,
that the land width between adjacent grooves in a range between about 0.5 to about 10 mm. Press arrangement according to claim 154,
characterized,
that the land width between adjacent grooves in a range between about 1 to about 7 mm. Press arrangement according to claim 155,
characterized,
that the land width between adjacent grooves in a range between about 1.5 to about 5 mm. Press arrangement according to one of claims 151 to 156,
characterized,
that the ratio of web width to the groove depth is in a range between about 0.2 to about 10 degrees. Press arrangement according to claim 157,
characterized,
that the ratio of web width to the groove depth in a range between about 0.5 to about. 5 Press arrangement according to claim 158,
characterized,
that the ratio of web width to the groove depth is in a range between about 0.8 to about 2.0. Press arrangement according to one of claims 143 to 159,
characterized,
that a respective roll cover is both drilled and grooved. Press arrangement according to one of claims 143 to 160,
characterized,
in that at least one press nip (18, 22, 26) is formed between rolls (14, 16, 20, 24), of which only one is provided with a grooved or drilled roll cover. Press arrangement according to one of claims 143 to 161,
characterized,
in that at least one press nip (18, 22, 26) is formed between rollers (14, 16, 20, 24), both of which are each provided with a grooved or drilled roll cover. Press arrangement according to one of claims 143 to 162,
characterized,
that at least a portion of the respective roller cover completely penetrating holes simultaneously serve as suction holes. Press arrangement according to one of the preceding claims,
characterized,
that the transfer belt (12) is grooved. Press arrangement according to claim 164,
characterized,
that the scoring is provided on the inside of the transfer belt (12). Press arrangement according to claim 164 or 165,
characterized,
that the groove depth is ≤ 80% of the strip thickness. Press arrangement according to one of the preceding claims,
characterized,
that the thickness of the transfer belt (12) is in a range of about 1 to about 10 mm. Press arrangement according to one of claims 164 to 167,
characterized,
that the grooved transfer belt (12), the ratio of web width to the groove depth in a range between about 0.5 and about. 5 Press arrangement according to claim 168,
characterized,
that the ratio of web width to the groove depth is in a range between about 0.8 and about. 2 Press arrangement according to one of the preceding claims,
characterized,
that rollers (16, 14, 24) are provided with a respective diameter> 450 mm. Press arrangement according to one of claims 136 to 170,
characterized,
in that both press nips (18, 22) provided on the central roll are each formed by a roll nip, and in that the roll cover at least of the press roll (16), that of the central roll (14) to form the first roll nip (18, 18) provided at this central roll (14). 22) is assigned, is executed accordingly. Press arrangement according to one of claims 136 to 171,
characterized,
in that both press nips (18, 22) provided on the central roll (14) are each formed by a roll nip and that the roll cover at least of the press roll (20), that of the central roll to form the second roll nip (22) provided on this central roll (14). is assigned, is carried out accordingly. Press arrangement according to one of claims 136 to 172,
characterized,
in that both press nips (18, 22) provided on the central roll (14) are each formed by a roll nip and that the roll cover at least of the central roll (14) is designed accordingly. Press arrangement according to one of claims 136 to 170,
characterized,
in that the first press nip (18) provided on the central roll (14) is formed by a nip and the second press nip (22) provided on the central roll (14) is formed by a shoe press nip and in that the roll cover is at least the press roll (16), that of the central roll (14) for forming the first at this central roller (14) provided Pressnips (18) is assigned, is carried out accordingly. A press arrangement according to any one of claims 136 to 170 and 174,
characterized,
in that the first press nip (18) provided on the central roll (14) is formed by a nip and the second press nip (22) provided on the central roll (14) is formed by a shoe press nip and that the roll cover at least the central roller (14) is carried out accordingly. Press arrangement according to one of the preceding claims,
characterized,
in that at least one scraper and / or at least one spray tube is provided in order to remove air and water entrained on the inside of the transfer belt (12) and / or contaminants present on the inside and on the outside of the transfer belt (12).

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