Drying section

Information

  • Patent Grant
  • 6493962
  • Patent Number
    6,493,962
  • Date Filed
    Friday, May 11, 2001
    23 years ago
  • Date Issued
    Tuesday, December 17, 2002
    22 years ago
Abstract
Drying section of a machine for producing a material web. The drying section includes at least one web guidance device and at least one wire arranged to guide the material web through the at least one web guidance device. The at least one web guidance device is structured and arranged to direct pressurized gas at the material web so that, in a web travel direction, the material web is alternately lifted from the at least one wire and resting against the at least one wire.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The invention relates to a drying section of a machine for producing a material web, in particular a paper or cardboard web. The invention further relates to an airborne web dryer for such a drying section.




2. Discussion of Background Information




In the multi-cylinder drying sections that have been common up to now, the paper web is guided over steam-heated cylinders or over steam-heated cylinders and wire suction rolls for the purpose of drying. Especially at the beginning of drying, when the moist paper web does not yet have sufficient strength, problems often occur with respect to web guidance, which can particularly be attributed to the fact that the web, which is still moist and poorly ventilated, sticks to the smooth contact surfaces, which are absolutely necessary for a sufficient heat transfer. In order to be able to remove the web from the cylinders, a sufficient web tension is necessary, which can be produced before or directly after the initial smooth contact surfaces by pulling, i.e., corresponding differential speeds. However, this often leads to web tears and an overstretching of the web edges. Therefore, as a rule, care should be taken that the drying occurs more slowly, i.e., e.g., a lower steam pressure is present at the beginning, which also means that the necessary drying section becomes longer overall. The problems mentioned above occur more intensely at higher web speeds.




SUMMARY OF THE INVENTION




The present invention provides a drying section of the type mentioned at the outset which, at high speeds, simultaneously guarantees as optimal a drying rate as possible at the beginning of the drying and a secure web guidance. Moreover, an airborne web dryer is provided that is appropriate for such a drying section.




In particular, the instant invention includes at least one web guidance device through which the material web is guided along with a wire, and in which the material web can be impinged with pressurized gas in such a way that, in the web travel direction, it is alternately lifted up from the wire and rests against it.




Because of this construction, the material web, which is still relatively moist, must no longer be prematurely removed from a smooth surface. As a result of avoiding smooth contact surfaces at the beginning of drying, the danger of web tears and of an overstretching of the web edges is virtually eliminated. In particular, high drying rates are now possible as well, whereby the total length of the drying section is shortened correspondingly. Since the web must not be subjected to high removal stresses caused by pulling until it has higher dry contents, the stressing of the web after the pressing section is minimized. Finally, correspondingly higher machine speeds are possible.




In a preferred practical embodiment of the drying section according to the invention, at least one pressurized gas-driven web guidance device embodied or formed as an airborne web dryer is provided. Such an airborne web dryer, e.g., can be provided directly after the pressing section and before the first drying cylinder. As a result of the combination of the airborne web dryer with a drying wire, even a web with a lower strength (for example, a web with higher moisture, e.g., before cylinder drying) can be dried.




While the material web can be deflected by a corresponding gas pressure distribution in the respective web guidance device, e.g., in a waveform, and can, e.g., be stabilized in a sine wave, the wire in the respective pressurized gasdriven web guidance devices tends to have a progression at least essentially in a straight line.




The web guidance device appropriately includes several nozzles arranged one behind the other for the purpose of impinging the material web with pressurized gas. Preferably, such nozzles are provided on both sides of the material web. Here, in particular, several banks of nozzles can be provided which extend in the direction of the web width.




In a preferred practical embodiment of the drying section according to the invention, at least one pressurized gas-driven web guidance device is arranged before the first drying cylinder.




In particular, air can be used as the pressurized gas.




It is also advantageous for at least one impingement dryer provided with a drying hood to be provided, by which the material web can be impinged with a hot air and/or a hot steam. Here, the material web is preferably guided over at least one support roll, in particular a larger support roll, with an impingement dryer assigned to it.




Again, such an impingement dryer is preferably arranged before the first drying cylinder.




Before the material web is pulled off a smooth heated surface for the first time, it can be predried by at least one airborne web dryer and, optionally, at least one impingement dryer. The gas and/or air drying appropriately occurs until a sufficient dry content is reached at which the necessary web tension can be applied in a problem-free manner.




In a preferred practical embodiment, the material web already has a dry content of at least approximately 58% to approximately 65% upon leaving the first drying cylinder or being pulled from a smooth heated surface for the first time. Here, as already mentioned, a part of the gas and/or air drying can also occur by an impingement dryer or an impingement hood.




Advantageously, at least one pressurized gas-driven web guidance device is provided subsequent to the last pressing nip of the pressing section.




In certain cases, it is appropriate for the material web, subsequent to the last pressing nip of the pressing section, first to be guided by at least one pressurized gas-driven web guidance device and subsequently by a support roll, in particular a larger support roll, with an impingement dryer assigned to it before it is guided to the first drying cylinder.




The drying speed in the region of a respective web guidance device embodied as an airborne web dryer and/or a respective impingement dryer can advantageously be regulated using the pressurized gas temperature, speed, and/or moisture.




The air permeability of a wire assigned to a respective web guidance device driven by pressurized gas is advantageously selected to be as high as possible. Thus, in a preferred embodiment, the air permeability of the respective wire is greater than approximately 300 cfm and preferably greater than approximately 500 cfm.




It is also advantageous for the material web to be guided in a closed draw from the last pressing nip of the press section to the first drying cylinder.




In certain cases, it is appropriate for the material web to be transferred directly from the pressing section to the wire assigned to a pressurized gas-driven web guidance device. However, the transfer of the material web from the pressing section to the wire assigned to a pressurized gas-driven web guidance device can also occur by means of at least one transfer belt or the like.




The material web can be removed from a felt (upper or lower felt) guided through the last pressing nip of the pressing section. However, removal directly from a pressing roll assigned to the last pressing nip of the pressing section is also conceivable.




In order to achieve the desired dry content, several airborne web dryers and/or several impingement dryers can also be provided.




A given pressurized gas-driven web guidance device can be arranged horizontally, vertically, or diagonally. In the latter case, the material web can be guided in the pressurized gas-driven web guidance device running diagonally, either generally diagonally upwards or generally diagonally downwards.




If several pressurized gas-driven web guidance devices are provided, at least a part of these web guidance devices can each have its own wire assigned to it.




In certain cases, it is also advantageous for at least one wire to be provided that is guided through several pressurized gas-driven web guidance devices.




In order to hold the material web on the wire, suction rolls, transfer foils and/or suction boxes can be provided before and/or after the pressurized gas-driven web guidance devices assigned thereto and/or between web guidance devices following one another.




For the purpose of transferring the web, the roll (suction roll or cylinder) following the last airborne web dryer can be partially wrapped by the wire assigned to the airborne web dryer or the web can be transferred from a suction roll to a subsequent drying wire.




In order to transfer the material web by a respective pressurized gas-driven driven web guidance device, it is practical for the web to be pressed against the wire and/or suctioned. This is possible, e.g., in that, in a respective pressurized gas-driven web guidance device, the web to be transferred is correspondingly impinged by pressurized gas only on its side facing away from the wire and/or is subjected to vacuum from the wire side.




In the latter case, vacuum boxes can be provided between the banks of nozzles provided on the side of the wire facing away from the material web.




The transfer by the gas and/or air dryers preferably occurs across the entire web width using the air dryers. However, the transfer can also occur partially or entirely with a transfer strip and corresponding transfer zones in suction and blow boxes. In the case of a transfer strip, care must be taken that the rest of the web can be moved by the felt or wire into the pulper or cellar before the corresponding gas and/or air dryer.




In certain cases, it can also be advantageous for at least one web guidance device to be provided, by which the material web can be impinged with pressurized air of a lower temperature in the range of preferably approximately 20 to 150°. Thus, in particular, the use of such a pressurized gas-driven web guidance device as a pure transfer element is also possible.




In order to allow a shrinkage in the crosswise machine direction that is as unrestricted as possible and thus to achieve small differences in crosswise shrinkage between the edges and the middle, at least one airborne web dryer without a wire can be provided between the last pressing nip of a pressing section and the first drying cylinder and/or within a predrying section. This possibility exists independently of whether or not another airborne web dryer is provided with a wire.




The airborne web dryer according to the invention includes a wire serving to support the web.




The suspended guidance device according to the invention, for example, embodied as an airborne web dryer, (optionally in connection with at least one impingement dryer) can be used, in particular at the beginning of drying between the press and the first drying cylinder, preferably in combination with a Tandem NipcoFlex press or DuoCentri press with a belt around the central roll or other press configurations in which the web is not pulled off of a smooth roll. Use within the (pre)drying section is also conceivable in order to allow as unrestricted a shrinkage in the machine cross direction as possible and thus to achieve small differences between the edges and the middle. Moreover, the web guidance device can also be operated with a low gas and/or air temperature, for example, in the region from approximately 20 to approximately 150° C. Thus, the guidance device can also be used simply as a transfer element.




The present invention is directed to drying section of a machine for producing a material web. The drying section includes at least one web guidance device and at least one wire arranged to guide the material web through the at least one web guidance device. The at least one web guidance device is structured and arranged to direct pressurized gas at the material web so that, in a web travel direction, the material web is alternately lifted from the at least one wire and resting against the at least one wire.




In accordance with a feature of the instant invention, the material web includes one of a paper and cardboard web.




According to another feature of the invention, the at least one web guidance device is driven by pressurized gas and is formed as an airborne web dryer. The at least one wire is guided in a straight line through the pressurized gas-driven web guidance device.




The at least one web guidance device includes a plurality of nozzles arranged one behind the other in the web travel direction for directing the pressurized gas at the material web. The plurality of nozzles are positioned on both sides of the at least one wire. The plurality of nozzles include nozzle banks extending across a web width.




Moreover, the at least one web guidance device is arranged before a first drying cylinder. The at least one web guidance device includes a pressurized gas driven web guidance device.




In accordance with another feature of the present invention, the pressurized gas is air.




Still further, at least one impingement dryer with a drying hood is provided, and the at least one impingement dryer subjects the material web to at least one of hot air and hot steam impingement. At least one support or suction roll is associated with the at least one impingement dryer. The material web is guided over the at least one support or suction roll. The at least one support or suction roll is arranged so that, as the material web is guided over the at least one support or suction roll, the material web is subjected to the at least one of the hot air and hot steam impingement. The at least one impingement dryer is located before a first drying cylinder. Further, the at least one impingement dryer is located behind the at least one web guidance device in the web travel direction.




In accordance with a further feature of the invention, at least one of when leaving a first drying cylinder and a first time pulled off a smooth heated surface, the material web has a dry content greater than at least about 58% to about 65%.




The at least one web guidance device is located subsequent to a last pressing nip of a pressing section in the web travel direction.




The drying section also includes an impingement dryer and at least one support or suction roll associated with the impingement dryer. Subsequent to a last pressing nip of a pressing section, the material web is guided through the at least one web guidance device and is guided over at the least one support or suction roll before being guided to a first drying cylinder.




Further, the drying section includes an impingement dryer through which the material web is guided. The at least one web guidance device is formed as an airborne dryer, and a drying speed in a region of at least one of the airborne web dryer and the impingement dryer is regulatable via at least one of a pressurized gas temperature, speed, and moisture.




An air permeability of the at least one wire is greater than approximately 300 cfm, and the air permeability can be greater than approximately 500 cfm.




According to another feature of the present invention, the material web departing from a last pressing nip of the pressing section is guided to a first drying cylinder in a closed draw.




In accordance with still another feature of the instant invention, the material web is transferred from a pressing section directly to the at least one wire.




According to a still further feature of the invention, the at least one web guidance device includes a plurality of web guidance devices and the at least one wire comprises a plurality of wires respectively associated with each of the plurality of web guidance devices.




Further still, the material web is transferred from a pressing section to the at least one wire via at least one transfer belt.




A felt is arranged through a last pressing nip of a pressing section, and the material web is transferred to the at least one wire from the felt.




Moreover, the material web is removed directly from a pressing roll of a last pressing nip of a pressing section.




In accordance with another feature of the invention, the dryer section includes at least one impingement dryer, and the at least one web guidance device includes an airborne web dryer. At least one of the at least one web guidance device comprises a plurality of web guidance device and the at least one impingement dryer comprises a plurality of impingement dryers.




The at least one web guidance device is oriented to guide the material web in a substantially horizontal direction.




Further, the at least one web guidance device is oriented to guide of the material web in a substantially vertical direction.




Still further, the at least one web guidance device is oriented to guide the material web in a generally diagonally upward direction.




Moreover, the at least one web guidance device is oriented to guide the material web in a generally diagonally downward direction.




In accordance with a feature of the invention, the at least one web guidance device includes a plurality of web guidance devices, and at least some of the plurality of web guidance devices are associated with the at least one wire.




According to still another feature of the invention, the at least one web guidance device includes a plurality of web guidance devices, and the at least one wire is guided through the plurality of web guidance devices.




The at least one web guidance device includes a plurality of web guidance devices arranged to follow one another to guide the material web on the at least one wire, and the dryer section further includes at least one of suction rolls, transfer foils, and suction boxes which are located at least one or before, between, and after the plurality of web guidance devices.




Further, in the at least one web guidance device, at least one of the pressurized gas is directed at a surface of the material web facing away from the at least one wire and a vacuum is applied to a surface of the material facing the at least one wire.




The at least one web guidance device includes nozzle banks positioned on a side of the at least one wire opposite the material web to direct the pressurized gas toward the material web and vacuum boxes arranged between the nozzle banks.




Moreover, the pressurized gas directed at the material web has a temperature of in a range of approximately 20° C. to approximately 150° C.




The present invention is directed to a drying section of a machine for producing a material web that includes at least one airborne web dryer with at least one wire positioned at least one of (a) between a last pressing nip of a pressing section and a first drying cylinder and (b) inside a predrying section.




According to a feature of the invention, the material web includes one of a paper and cardboard web.




The present invention is directed to an airborne web dryer including a wire arranged to support the web.




Further, the airborne web dryer includes a plurality of nozzles arranged in a web travel direction so that the material web alternatingly is lifted off the at wire and resting on the wire.




Also, the material web includes one of a paper and cardboard web.




The present invention is directed to a process for transporting a material web through a drying section of a machine that includes at least one web guidance device and at least one wire. The process includes guiding the material web through the at least one web guidance device on the at least one wire, and directing pressurized gas at the material web, whereby, in a web travel direction, the material web is alternately lifted from the at least one wire and resting against the at least one wire.




The process further includes suctioning, between the areas at which pressurized gas is directed in the web travel direction, the material web toward the at least one wire.




Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.











BRIEF DESCRIPTION OF THE DRAWINGS




The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:





FIG. 1

schematically illustrates a pressurized gas-driven web guidance device, for example, embodied as an airborne web dryer, with an assigned wire;





FIG. 2

schematically illustrates an embodiment of a drying section with two pressurized gas-driven web guidance devices, for example, embodied as airborne web dryers, and an impingement dryer, with a common wire being guided through both web guidance devices; and





FIG. 3

schematically illustrates another embodiment of a drying section with two pressurized gas-driven web guidance devices, for example, embodied as airborne web dryers, with each of these two web guidance devices having its own wire.











DETAILED DESCRIPTION OF THE PRESENT INVENTION




The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.





FIG. 1

shows in a schematic partial depiction a web guidance device


10


driven by pressurized gas, pressurized air in this case, which can be embodied as an airborne web dryer in particular.




A wire


12


, serving to support the web is assigned to web guidance device


10


, which wire is guided through web guidance device


10


along with material web


14


. Material web


14


can, in particular, be a paper or cardboard web.




In web guidance device


10


, material web


14


is impinged with pressurized air in such a way that it is alternately lifted from and resting against wire


12


in web travel direction L. Because of the air permeability, wire


12


has an at least essentially straight progression inside web guidance device


10


.




In order to correspondingly impinge material web


14


, web guidance device


10


has several nozzles


16


arranged one after the other in web travel direction L. Nozzles


16


are provided on both sides of wire


12


and, therefore, of material web


14


. In the present case, several nozzle banks


16


, each running in the direction of the web width, are arranged on both sides.




The air permeability of wire


12


is appropriately greater than approximately 300 cfm and preferably greater than 500 cfm.




Moreover, nozzles


16


can be embodied and/or controllable in such a way that, in order to transfer material web


14


, web


14


is impinged with pressurized gas, in this case pressurized air, in web travel direction L in web guidance device


10


only on the side facing away from wire


12


. However, in order to transfer material web


14


, material web


14


can also be subjected to a vacuum from the wire side through wire


12


. For this purpose, vacuum boxes (not shown) can be arranged between nozzle banks


16


provided on the lower side of wire


12


.




In principle, it is also possible to operate web guidance device


10


with pressurized gas, in particular pressurized air, with a lower temperature in the range of preferably approximately 20° C. to approximately 150° C. Thus, web guidance device


10


can also be used in particular as a pure transfer element.





FIGS. 2 and 3

each show in a purely schematic depiction a drying section


18


of a machine for producing a material web, which can particularly be a paper or cardboard web.




In the embodiments of

FIGS. 2 and 3

, two web guidance devices


10


,


10


′ of the type described in

FIG. 1

are provided. These two web guidance devices


10


,


10


′ are respectively arranged after a last pressing nip


20


of a pressing section


22


and before a first drying cylinder


24


of a drying section


18


.




In the embodiment according to

FIG. 2

, an impingement dryer


28


with a drying or impingement hood


26


is provided subsequent to the two web guidance devices


10


,


10


′, by which dryer material web


14


can be subjected to hot air and/or hot steam impingement. Here, material web


14


is guided with its own wire


30


assigned to impingement dryer


28


over a larger support roll


32


provided with drying hood


26


.




The drying speed in the region of a respective web guidance device


10


,


10


′, for example, embodied or formed as an airborne web dryer, as well as impingement dryer


28


provided in the embodiment according to

FIG. 2

may be regulated using pressurized air temperature, speed, and/or moisture. Here, the drying can occur in the various embodiments, for example, in such a way that the material web


14


(see also FIG.


1


), upon leaving the first drying cylinder


24


or the first time it is pulled off of a smooth heated surface, already has a dry content that is preferably greater than approximately


60


to approximately 65%.




In both cases, as can be discerned from

FIGS. 2 and 3

, material web


14


is guided in a closed draw beginning from last pressing nip


20


of pressing section


22


to first drying cylinder


24


. Here, material web


14


is removed in each embodiment from lower felt


34


that is guided through last pressing nip


20


of pressing section


22


.




In the embodiment according to

FIG. 2

, a common wire


12


is guided through the two web guidance devices


10


,


10


′. Material web


14


is removed from lower felt


34


that is guided through last pressing nip


20


of pressing section


22


in region of a suction roll


36


.




Between the two web guidance devices


10


,


10


′, wire


12


is guided over a further suction roll


38


. A suction roll


40


is provided behind the web guidance device


10


′ in the web travel direction L, over which wire


12


is guided. Subsequently to this, the material web


14


is accepted by the wire


30


assigned to the impingement dryer


28


. For example, a transfer foil


44


, a suction box


46


, or the like can be provided at the acceptance point. In the region of a further suction roll


48


, material web


14


is transferred by wire


30


to a drying wire


45


, by which the web is finally guided to first drying cylinder


24


.




In the embodiments shown in

FIGS. 2 and 3

, material web


14


is guided generally diagonally downwards in first web guidance device


10


and is guided generally diagonally upwards in second web guidance device


10


′.




In the embodiment according to

FIG. 3

, only two pressurized gasdriven web guidance devices


10


,


10


′ are used. In other words, an impingement dryer is not provided here. Each web guidance device


10


,


10


′ has its own wire


12


,


12


′ assigned to it. Here, the transfer of material web


14


from lower wire


34


of pressing section


22


to wire


12


guided through first web guidance device


10


occurs by a transfer belt


50


. Here, the removal from lower wire


34


occurs in the region of a suction roll


52


over which transfer belt


50


is guided. The web transfer onto wire


12


again occurs in the region of a suction roll


36


assigned to wire


12


. The transfer of the material web


14


from wire


12


to wire


12


′ guided through second web guidance device


10


′ occurs in the region of another suction roll


54


, which is assigned to wire


12


′. Wire


12


′ serves simultaneously as a drying wire by which the material web


14


is guided over another suction roll


56


to first drying cylinder


18


subsequently to second web guidance device


10


′.




As already mentioned, at least one of the pressurized gas-driven web guidance devices


10


,


10


′ can be embodied as an airborne web dryer. In principle, however, it is also conceivable to operate at least one of these web guidance devices


10


,


10


′ with pressurized gas or pressurized air with a lower temperature and, for example, use it at least predominately as a transfer element.




In principle, it is also possible to provide at least one airborne web dryer without a wire between last pressing nip


20


of pressing section


22


and first drying cylinder


18


and/or within a predrying section.




It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.




LIST OF REFERENCE CHARACTERS






10


Web guidance device, airborne web dryer






10


′ Web guidance device, airborne web dryer






12


Wire






12


′ Wire






14


Material web






16


Nozzles, banks of nozzles






18


Drying section






20


Last pressing nip






22


Pressing section






24


First drying cylinder






26


Drying hood






28


Impingement dryer






30


Wire






32


Support roll






34


Felt






36


Suction roll






38


Suction roll






40


Suction roll






42


Suction roll






44


Transfer foil






45


Drying wire






46


Suction box






48


Suction roll






50


Transfer belt






52


Suction roll






54


Suction roll






56


Suction roll




L Web travel direction



Claims
  • 1. A drying section of a machine for producing a material web comprising:at least one web guidance device; and at least one wire arranged to guide the material web through the at least one web guidance device; and said at least one web guidance device is arranged before, relative to a web travel direction, a first drying cylinder and after a last press nip, wherein said at least one web guidance device is structured and arranged to direct pressurized gas at the material web so that, in a web travel direction, the material web is alternately lifted from said at least one wire and resting against said at least one wire.
  • 2. The drying section in accordance with claim 1, wherein the material web comprises one of a paper and cardboard web.
  • 3. The drying section in accordance with claim 1, wherein said at least one web guidance device is driven by pressurized gas and is formed as an airborne web dryer.
  • 4. The drying section in accordance with claim 3, wherein said at least wire is guided in a straight line through said pressurized gas-driven web guidance device.
  • 5. The drying section in accordance with claim 1, wherein said at least one web guidance device comprises a plurality of nozzles arranged one behind the other in the web travel direction for directing said pressurized gas at the material web.
  • 6. The drying section in accordance with claim 5, wherein said plurality of nozzles are positioned on both sides of said at least one wire.
  • 7. The drying section in accordance with claim 5, wherein said plurality of nozzles comprises nozzle banks extending across a web width.
  • 8. The drying section in accordance with claim 1, wherein said at least one web guidance device is arranged before a first drying cylinder.
  • 9. The drying section in accordance with claim 8, wherein said at least one web guidance device comprises a pressurized gas driven web guidance device.
  • 10. The drying section in accordance with claim 1, wherein said pressurized gas is air.
  • 11. The drying section in accordance with claim 1, further comprising at least one impingement dryer with a drying hood, wherein at least one impingement dryer subjects the material web to at least one of hot air and hot steam impingement.
  • 12. The drying section in accordance with claim 11, further comprising at least one support or suction roll associated with said at least one impingement dryer, wherein the material web is guided over said at least one support or suction roll.
  • 13. The drying section in accordance with claim 12, wherein said at least one support or suction roll is arranged so that, as the material web is guided over said at least one support or suction roll, the material web is subjected to the at least one of the hot air and hot steam impingement.
  • 14. The drying section in accordance with claim 12, wherein said at least one impingement dryer is located before a first drying cylinder.
  • 15. The drying section in accordance with claim 12, wherein said at least one impingement dryer is located behind said at least one web guidance device in the web travel direction.
  • 16. The drying section in accordance with claim 1, wherein at least one of when leaving a first drying cylinder and a first time pulled off a smooth heated surface, the material web has a dry content greater than at least about 58% to about 65%.
  • 17. The drying section in accordance with claim 1, wherein said at least one web guidance device is located subsequent to a last pressing nip of a pressing section in the web travel direction.
  • 18. The drying section in accordance with claim 1, further comprising an impingement dryer and at least one support or suction roll associated with said impingement dryer,wherein, subsequent to a last pressing nip of a pressing section, the material web is guided through said at least one web guidance device and is guided over said at least one support or suction roll before being guided to a first drying cylinder.
  • 19. The drying section in accordance with claim 1, further comprising an impingement dryer through which the material web is guided,wherein said at least one web guidance device is formed as an airborne dryer, and wherein a drying speed in a region of at least one of said airborne web dryer and said impingement dryer is regulatable via at least one of a pressurized gas temperature, speed, and moisture.
  • 20. The drying section in accordance with claim 1, wherein an air permeability of said at least one wire is greater than approximately 300 cfm.
  • 21. The drying section in accordance with claim 20, wherein the air permeability is greater than approximately 500 cfm.
  • 22. The drying section in accordance with claim 1, wherein the material web departing from a last pressing nip of the pressing section is guided to a first drying cylinder in a closed draw.
  • 23. The drying section in accordance with claim 1, wherein the material web is transferred from a pressing section directly to said at least one wire.
  • 24. The drying section in accordance with claim 1, wherein said at least one web guidance device comprises a plurality of web guidance devices and said at least one wire comprises a plurality of wires respectively associated with each of said plurality of web guidance devices.
  • 25. The drying section in accordance with claim 1, wherein the material web is transferred from a pressing section to said at least one wire via at least one transfer belt.
  • 26. The drying section in accordance with claim 1, wherein a felt is arranged through a last pressing nip of a pressing section, and the material web is transferred to said at least one wire from said felt.
  • 27. The drying section in accordance with claim 1, wherein the material web is removed directly from a pressing roll of a last pressing nip of a pressing section.
  • 28. The drying section in accordance with claim 1, further comprising at least one impingement dryer, and said at least one web guidance device comprises an airborne web dryer,wherein at least one of: said at least one web guidance device comprises a plurality of web guidance device and said at least one impingement dryer comprises a plurality of impingement dryers.
  • 29. The drying section in accordance with claim 1, wherein said at least one web guidance device is oriented to guide the material web in a substantially horizontal direction.
  • 30. The drying section in accordance with claim 1, wherein said at least one web guidance device is oriented to guide of the material web in a substantially vertical direction.
  • 31. The drying section in accordance with claim 1, wherein said at least one web guidance device is oriented to guide the material web in a generally diagonally upward direction.
  • 32. The drying section in accordance with claim 1, wherein said at least one web guidance device is oriented to guide the material web in a generally diagonally downward direction.
  • 33. The drying section in accordance with claim 1, wherein said at least one web guidance device comprises a plurality of web guidance devices, andwherein at least some of said plurality of web guidance devices are associated with said at least one wire.
  • 34. The drying section in accordance with claim 1, wherein said at least one web guidance device comprises a plurality of web guidance devices, andwherein said at least one wire is guided through said plurality of web guidance devices.
  • 35. The drying section in accordance with claim 1, wherein said at least one web guidance device comprises a plurality of web guidance devices arranged to follow one another to guide the material web on said at least one wire, and said dryer section further comprises:at least one of suction rolls, transfer foils, and suction boxes which are located at least one or before, between, and after said plurality of web guidance devices.
  • 36. The drying section in accordance with claim 1, wherein, in said at least one web guidance device, at least one of:the pressurized gas is directed at a surface of the material web facing away from said at least one wire and a vacuum is applied to a surface of the material facing said at least one wire.
  • 37. The drying section in accordance with claim 1, wherein said at least one web guidance device comprises nozzle banks positioned on a side of said at least one wire opposite the material web to direct said pressurized gas toward the material web and vacuum boxes arranged between said nozzle banks.
  • 38. The drying section in accordance with claim 1, wherein the pressurized gas directed at the material web has a temperature of in a range of approximately 20° C. to approximately 150° C.
  • 39. A drying section of a machine for producing a material web comprising:at least one airborne web dryer with at least one wire positioned at least one of (a) between a last pressing nip of a pressing section and a first drying cylinder and (b) inside a predrying section, wherein the at least one airborne web dryer is structured and arranged to direct pressurized gas at the material web so that, in a web travel direction, the material web is alternately lifted from said at least one wire and resting against said at least one wire.
  • 40. The drying section in accordance with claim 39, wherein the material web comprises one of a paper and cardboard web.
  • 41. An airborne web dryer comprising:a single wire arranged to support the web, wherein said single wire is arranged to transport the web after a last press nip and before a first drying cylinder.
  • 42. The airborne web dryer in accordance with claim 41, further comprising a plurality of nozzles arranged in a web travel direction so that the material web is alternatingly lifted off the wire and resting on the wire.
  • 43. The airborne web dryer in accordance with claim 41, wherein the material web comprises one of a paper and cardboard web.
  • 44. A process for transporting a material web through a drying section of a machine that includes at least one web guidance device and at least one wire, said process comprising:pressing the material web in a last press nip; guiding the material web from the last press nip through the at least one web guidance device on the at least one wire; directing pressurized gas at the material web, whereby, in a web travel direction, the material web is alternately lifted from said at least one wire and resting against said at least one wire; and guiding the material web from the at least one guidance device to a first drying cylinder.
  • 45. The process in accordance with claim 44, further comprising suctioning, between the areas at which pressurized gas is directed in the web travel direction, the material web toward the at least one wire.
Priority Claims (1)
Number Date Country Kind
100 24 358 May 2000 DE
CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of German Patent Application No.100 24 358.4, filed on May 17, 2000, the disclosure of which is expressly incorporated by reference herein in its entirety.

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Number Name Date Kind
2671279 Blanchard Mar 1954 A
4965918 Magin Oct 1990 A
5770015 Grossmann Jun 1998 A
5865955 Ilvespaa Feb 1999 A
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6004430 Ilvespaa Dec 1999 A
6189233 Halmschlager Feb 2001 B1
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Foreign Referenced Citations (1)
Number Date Country
2942030 May 1980 DE