EP0988417A1

EP0988417A1 - Dryer section

Info

Publication number: EP0988417A1
Application number: EP98937437A
Authority: EP
Inventors: Guenter Halmschlager; Walter Holzer; Karl Steiner
Original assignee: Voith Sulzer Papiermaschinen GmbH
Current assignee: Voith Patent GmbH
Priority date: 1997-06-03
Filing date: 1998-06-03
Publication date: 2000-03-29
Anticipated expiration: 2018-06-03
Also published as: DE19723163A1; EP0988417B1; US6189233B1; DE59813698D1; WO1998055687A1

Abstract

The invention relates to a dryer section (1) of a machine for producing and/or processing a web of material (9), especially a paper or cardboard web, comprising at least one heatable drying cylinder (3) which around part of its circumference is surrounded by the material web and at least one support band (5, 7), and an overpressure cap (27) which is able to impinge upon the drying cylinder with a pressurized liquid or gaseous medium. Said drying section is characterized in that the temperature of the medium is lower than the temperature on the outside of the partial circumference of the drying cylinder surrounded by the material web and the support band.

Description

DRY LOT

description

The invention relates to a dryer section of a machine for producing and / or processing a material web, in particular paper or cardboard web, according to the preamble of claim 1.

Dryer sections of the type mentioned here are known (DE-OS 195 40 003.8). A known dryer section comprises a heatable drying cylinder, over which a material web and a porous support belt are guided. The material web is pressed onto the circumference of the drying cylinder by the prestressed support belt. An overpressure hood is assigned to the drying cylinder, which acts on a partial circumference of the drying cylinder with a pressurized gaseous medium. The gas pressure is directly on the side of the material web facing away from the drying cylinder. This improves the drying contact between the material web and the surface of the drying cylinder. It has been found to be particularly disadvantageous that the discharge of the liquid emerging as vapor from the material web is hindered by the support belt, so that only relatively low drying rates can be achieved. It is therefore an object of the invention to provide a dryer section of the type mentioned which does not have this disadvantage.

To solve this problem, a dryer section is proposed which has the features mentioned in claim 1. Because the temperature of the liquid or gaseous medium is lower than the temperature on the outside of the part circumference of the drying cylinder which is wrapped by the material web and the support belt, a high liquid discharge from the material web can be achieved. The support belt and the side of the web of material lying against the support belt are cooled by the preferably liquid medium, so that a temperature gradient arises from the heated drying cylinder in the direction of the support belt. As a result, the heat flow is increased and the discharge direction of the liquid, which partially emerges as vapor from the material web, is adjusted. The liquid therefore preferably emerges from the material web on the side lying against the support band. Due to the cooling of the support belt by means of the medium, the liquid precipitates as condensate in the support belt immediately after it leaves the material web and is absorbed by the latter. A high drainage capacity is achieved by cooling the support belt and the material web, so that the drying capacity of the dryer section can be increased while the overall length remains the same.

An exemplary embodiment of the drying section is preferred in which at least one further, second support belt is guided around the outside of the drying cylinder becomes. The second support belt is thus guided such that the first support belt is arranged between the material web and the second support belt. Characterized in that the second support belt is cooled directly with the medium under pressure, its temperature is lower than that of the first support belt, so that the liquid emerging as vapor from the material web is reflected in the second support belt as condensate. The steam emerging from the material web thus initially penetrates the porous first support band and is taken up by the second support band, so that the rewetting of the material web can be kept low. It is of course also possible to guide more than two support belts, for example three support belts, around the outside of the drying cylinder, which are cooled by the gaseous medium.

In an advantageous embodiment it is provided that the second support band has a coarser structure than the first support band. The support bands usually have a fabric-like structure. The fabric can have threads intertwined with one another, for example threads consisting of several individual threads. In connection with the present invention, the term "structure" is understood to mean the structure of the fabric, that is to say that a support band with a coarse structure has larger gaps between the intertwined threads than a support band with a finer structure, the threads of which are more closely intertwined. The first support band, on which the material web rests, therefore has a finer structure than the second support band, so that markings against the material web can be safely avoided.

An embodiment of the drying section is particularly preferred, which is characterized in that a medium-impermeable sealing tape is guided around the outside of the drying cylinder. In connection with the present invention, an "impermeable sealing tape" is understood to mean a fluid and / or gas impermeable tape. At least one support tape is arranged between the sealing tape and the material web and serves to receive the liquid emerging from the material web. Due to the impermeability of the sealing tape, the media pressure applied to the outside of the sealing tape can be transferred in a defined manner to the support tape without the medium being connected to the material web. As a result, the material web is pressed onto the circumference of the drying cylinder, which leads to increased heat transport from the drying cylinder to the material web and thus increases the discharge rate of the liquid bound in the material web. In addition, the media web compresses the material web and thus significantly improves its web properties. The pressure of the preferably liquid medium, in particular water, is in a range from 0.001 bar to 12 bar absolute. The media pressure is preferably set as a function of the desired heating output and / or the type of material web and can optionally also be higher than 12 bar.

Furthermore, an embodiment of the dryer section is preferred in which the first support belt, the second support tape and / or the sealing tape between the discharge area in which the tapes / the tape run from the drying cylinder and the run-up area in which the tapes / tape run on the drying cylinder are / are guided outside the pressure chamber of the pressure hood. This ensures good accessibility to guide devices, for example guide rollers, over which the belts are guided. In addition, the construction of the pressure hood can be simplified.

Finally, an embodiment of the dry end is preferred in which the seals, for example sealing strips, by means of which the pressure space of the overpressure hood can be sealed off from the environment, interact in a contactless or contacting manner with rollers which are pressed against at least one sealing tape / support tape or the material web or only a small distance away from them. In an advantageous embodiment it is provided that at least one seal interacts directly with the surface of a roller. Sealing takes place in a circumferential area of the roller in which neither the material web nor a support tape or sealing tape lie. In the case of a touching seal, that is to say when the seal lies on the surface of the roller, wear on the strips and seals or damage to the material web can be avoided or kept small.

Further advantageous embodiments result from the remaining subclaims. The invention is explained in more detail below with reference to the drawing. Show it:

Figure 1 is a schematic side view of part of a first embodiment of a dryer section;

Figures each a schematic view of a 2 and 3 part of another embodiment of the dryer section;

Figure 4 shows a detail from a fourth embodiment of the dryer section;

FIG. 5 shows a schematic diagram of a fifth exemplary embodiment of a pressure device designed as an overpressure hood;

Figures each a schematic view of the 6 and 7 end face of a further embodiment of the dryer section and

Figures each show a section of an embodiment of the drying section in a side view.

The drying section described below can generally be used in connection with a machine for producing and / or processing a material web, for example in a coating machine. By way of example only, it is assumed that this is a dryer section of a paper making machine. Figure 1 shows schematically a part of an embodiment of a dryer section 1 in side view, namely a drying cylinder 3, over which a first support belt 5 and second support belt 7 are guided together with a material web 9. The support belts 5, 7 are also referred to as dryer fabrics or felts. In this embodiment, the material web 9 lies directly on the surface of the drying cylinder 3. The porous, that is gas and liquid permeable support belts 5, 7 are guided together via guide rollers 11, 13, 15, 17, 19 and 21 such that the first support belt 5 abuts the material web 9 and the second support belt 7 on the outside against the first support belt 5 . The support belts 5, 7 are prestressed so that the material web is pressed onto the circumference of the drying cylinder 3, which leads to an increase in the drying contact. It is possible to pretension the support tapes differently, so that, for example, the second support tape 7 has a lower pretension (tape tension) than the first support tape 5. To avoid inadmissibly coarse markings on the material web 9 by the first support tape 5 resting on the material web 9 , the support band 5 has a fine structure. “Fine structure” is understood to mean a small / distance between the pores or threads of the support band. The second support band 7 preferably has a coarse, but at least a coarser structure than the first support band 5, which will be discussed in more detail below. In order to enlarge the contact area between the heated surface of the drying cylinder 3 and the material web 9, the guide roller 11 arranged in the run-up area 23 and that in the run-off area 25 arranged guide roller 21 a relatively small distance from each other. The guide rollers 11, 21 each form a nip with the drying cylinder 3, through which the support belts 5, 7 and the material web 9 are passed.

In connection with the present invention, a “support band” is also understood to mean a band which is not used to support or press on the material web, but rather, for example, only to hold a liquid. The pretensioning of a support band not serving to support the material web can be chosen to be very small, preferably set.

In order to improve the drying contact of the material web 9 with the surface of the drying cylinder 3, an overpressure hood 27 is provided, which preferably extends over the entire length of the drying cylinder 3. The overpressure hood 27 here has an annular housing 28 which can be formed in one part or in several parts. As can be seen from FIG. 1, the guide rollers 11 to 21, over which the support belts 5, 7 are guided, are arranged in the interior of the overpressure hood 27. The overpressure hood 27 is closed to limit a pressure space 29 on its end faces by means of covers / not shown. The side covers are optionally sealed against the circumference, the end faces and / or on bearing journals of the drying cylinder and the guide rollers by means of contactless or suitable devices. The pressure chamber 29 is in the area in which the annular housing 28 of the overpressure hood 27 has an opening 31 has, through which the material web 9 is guided into the interior of the overpressure hood 27 into the pressure chamber 29, by means of seals 33 formed here as sealing strips and sealed with the drying cylinder forming a nip guide rollers 11, 21 from the environment. The guide rolls 11, 21 can be designed as press rolls, for example shoe presses, and pressed against the drying cylinder 3. The power transmission between the two unpressurized ends of the housing 28 of the overpressure hood 27, which is loaded by the overpressure in the pressure chamber 29, is preferably produced by a mechanical connection 32.

The seals 33 interact with a peripheral region of the guide rollers 11, 21, over which the support belts 5, 7 are guided. In the exemplary embodiment shown in FIG. 1, the seals 33 bear against the support belt 7 guided over the guide rollers 11, 21 in order to largely prevent pressure loss from the pressure chamber 29. Alternatively, it is possible that the seals 33 are at a small distance from the guide rollers 11, 21 or from the support belt 7 guided on the outside. When a pressurized gaseous medium is applied to the pressure chamber 29, so-called air knives can also be used instead of the seals 33, by means of which contactless sealing of the pressure chamber 29 can also be realized.

In the following it is assumed that the pressure chamber 29 is pressurized with a pressurized gaseous medium. Of course it is it is also possible to introduce a liquid under pressure, preferably water, into the pressure chamber 29. The generation of a pressure in the pressure chamber 29 with the aid of a liquid is particularly advantageous because, in comparison with a gaseous medium, a higher pressure with a lower flow, in particular with a smaller amount of the pressure medium, can be achieved with a liquid. The overpressure under which the liquid or gaseous medium introduced into the pressure chamber 29 is in a range from 0.001 bar to 12 bar absolute. The liquid / gas pressure in the pressure chamber 29 is preferably set as a function of the type of material web and / or the desired heating output of the drying cylinder or dryer section. It is also possible to vary the medium pressure during the drying process.

In the interior of the overpressure hood 27 there are a plurality of feeds 35, here a total of six, from which, as indicated by arrows, a pressurized liquid or gaseous medium, for example air, can be blown into the pressure chamber 29. The temperature of the gaseous medium, hereinafter referred to briefly as gas, is, for example, in a range from 40 ° C. to 80 ° C. The temperature of the gas is generally lower than the temperature on the outside of the partial circumference of the drying cylinder 3 wrapped by the material web 9 and the support bands 5, 7 and can accordingly also be, for example, 20 ° C. or 100 ° C. The pressure and the temperature of the gas blown into the pressure chamber 29 can be varied as desired. bar, preferably adjustable, for example as a function of the temperature of the drying cylinder 3. The internally heated drying cylinder 3 has a temperature which is preferably in a range from 140 ° C. to 190 ° C. The drying cylinder 3 can be heated with steam, oil, water, an infrared device, combustion gases or the like. Regardless of the heating of the drying cylinder 3, the heat input to the outside of the drying cylinder 3, that is to say on the cylinder surface, can be set in a defined manner. It is therefore possible to heat the drying cylinder 3 over its circumference or over its length so that the outside of the drying cylinder 3 has different temperatures.

The material web 9 is pressed onto the circumference of the drying cylinder 3 by the pressurized gas, so that the drying contact and thus the heat transfer both from the drying cylinder 3 to the material web 9 and within the material web 9 is increased. The gas also serves to cool both the support belts 5, 7 and the material web 9 on the side facing away from the drying cylinder 3. This results in a temperature gradient from the heated drying cylinder 3 in the direction of the support belts 5, 7. As a result, both the preferred discharge direction of the liquid emerging partly from the material web 9 as steam and partly as a liquid is set, and the heat flow is also increased if necessary. After the steam emerges from the material web 9, it is deposited directly as condensate in the support belts 5, 7 and is taken up by these. men. The temperature of the second support belt 7 guided on the outside is at least in some areas lower than the temperature of the first support belt 5 resting on the material web 9. The liquid emerging from the material web 9 is therefore largely or completely reflected in the outer second support belt 7, which as already described, has a coarser structure than the first support band 5 resting on the material web 9.

A relief zone 37 is provided in the pressure chamber 29 of the overpressure hood 27 and has a plurality of pressure zones 39, 40, 41, here a total of three. The relief zone 37 serves to prevent a too large and / or too rapid pressure drop at the exit of the material web 9 from the pressure chamber 29, which can lead to the destruction of the material web 9 by delamination. Furthermore, the pressure drop when leaving the pressure chamber 29 can be set in a targeted manner. In the embodiment shown in Figure 1, the pressure zones 39, 40, 41 are each formed by a chamber 43 provided with at least one flow channel. The pressure drops in the running direction of the material web 9 from one pressure zone to another, that is to say a lower pressure is present in the pressure zone 39 than in the pressure chamber 29 and a greater pressure than in the subsequent pressure zone 40. The pressure in the pressure zones 39, 40, 41 is - as indicated by arrows 45 - defined via the openings provided in the chambers 43. To discharge the liquid condensed in the support belts 5 and 7, the liquid is sealed off from the pressure chamber 29 by means of a seal. lines 33 'and 33 "sealed pressure zone 41 through a through opening 47 introduced into the housing 28 of the pressure hood 27 with the environment in flow connection.

The support belts 5, 7 pass through the printing zones 39, 40 and 41 together with the material web 9 resting on the drying cylinder 3. After the material web 9 has run off the drying cylinder 3, it is guided over a deflection roller 48 to a subsequent part of the paper making machine, while the support belts 5, 7 are guided to the run-up area via the guide rollers arranged inside the overpressure hood. The support bands pass through the pressure zone 41 in which the gas is passed through the support bands. As a result, the liquid taken up by the support bands 5, 7 is blown out and thus dried. Likewise, the drying of the support belts can be carried out, for example, by means of vacuum suction devices (pipe suction devices). The liquid is collected in a container 49 arranged outside the overpressure hood 27 and discharged from there together with the liquid.

Figure 2 shows schematically a part of another embodiment of the dryer section 1 in side view, namely a single-row dryer group, which comprises several, here a total of three drying cylinders 3a, 3b and 3c and two web guide rollers 51 and 53. Parts that correspond to those in Figure 1 are provided with the same reference numerals, so that reference is made to the description of Figure 1. In the following, only the sub- will be discussed in more detail. The overpressure hood 27 has a multi-part housing 28 which comprises a first housing part 28a and a second housing part 28b which essentially surround the drying cylinders 3a, 3b, 3c and the web guide rollers 51 and 53. The pressure chamber 29 of the overpressure hood 27 is sealed from the surroundings both by the guide rollers 11 and 21 and by seals 33. The guide roller 11 forms a nip with the first drying cylinder 3a or is arranged at a short distance from it and the guide roller 21 forms a nip with the drying cylinder 3c or is arranged at a small distance from the latter. The material web 9 and the support belts 5, 7 are guided through the respective nip or gap between the roller and drying cylinder. The sealing strips 33 attached to the second housing part 28b interact in a contactless or touching manner directly with the outside, that is to say a peripheral region of the drying cylinders 3a, 3c, which is not wrapped by either of the support bands 5, 7 or the material web 9. The sealing strips 33 attached to the first housing part 28a interact with or without contact with the circumferential region of the guide rollers 11 and 21 which is wrapped around by the support bands 5, 7.

As can be seen from FIG. 2, the support belts 5, 7 are guided together with the material web 9 in a meandering manner over the drying cylinders 3a, 3b, 3c and the web guide rollers 51, 53. The fact that the pressure hood 27 and the support belts 5, 7 are assigned to several drying cylinders, the structure of the drying section can be simplified. Figure 3 shows schematically a schematic diagram of a third embodiment of a dryer section 1. The same parts are provided with the same reference numerals, so that reference is made to the description of Figure 2. The pressure chamber 29 is sealed off from the environment here in the area of the material web 9 by two roller arrangements, each comprising two rollers 55 and 57. Between the rollers 55, 57, which are arranged at a distance from one another, either a small space is provided or are preferably designed as press rollers, that is to say that the rollers 55, 57 lie against one another on their circumference along a clamping pressure contact line and form a press nip through which the material web 9 is guided. Alternatively, it is possible for one or both rollers 55, 57 to be designed as so-called shoe presses. The pressure chamber 29 is sealed between the housing 28 and the rollers 55, 57 by means of sealing strips 33 which interact directly with the surface of the rollers 55 and 57.

The guide rollers 11 and 21 arranged in the run-up area 23, in which the material web 9 runs onto the first drying cylinder 3a, and in the run-off area 25, in which the material web 9 runs from the last drying cylinder 3c, are at a distance from the drying cylinders 3a, 3c arranged and are not used to seal the pressure chamber 29, but only to guide the support bands 5, 7th

Figure 4 shows schematically a section of an embodiment of a dryer section, namely one Overpressure box 27 in side view. Parts that correspond to those in Figure 1 are provided with the same reference numerals, so that reference is made to the description of Figure 1. The material web 9 is guided around the drying cylinder 3 together with the support tapes 5, 7 and an external, gas-impermeable sealing tape 59. The sealing tape 59 lies on the second support tape 7, so that the support tapes 5, 7 and the material web 9 are not in direct contact with the medium located on the opposite side of the sealing tape 59 in the pressure chamber 29 of the pressure hood 27. By means of the sealing tape 59, which consists, for example, of at least one metal, for example steel, the gas pressure applied to this outside can be transferred in a defined manner to the second support tape 7, so that the pressure on the material web 9 is increased to the circumference of the drying cylinder 3. The pressing force acting on the material web 9, which is caused without the sealing tape 59 only by the pretensioning of the support tapes 5, 7, can thus be increased by the gas under pressure. By increasing the pressure of the medium in the pressure chamber 29, that is to say the gas pressure in this exemplary embodiment, such high contact forces can be applied via the sealing tape 59 and the supporting tapes 5, 7 to the material web 9 as they would otherwise, if at all, only with a high one Biasing of the support bands 5, 7 can be achieved. With the help of the medium under pressure, even higher / contact forces can be generated than with a prestressing of the support bands, the maximum longitudinal tension of which is relatively small and limited by the properties of the support band material is can be achieved. The properties of the material web can be significantly improved by the high contact forces; in particular, the material web is compressed at high contact forces. A high pressure or a high pressure can therefore be applied to the material web 9 by the sealing tape 59, which is advantageous, for example, in the production of packaging papers. The material from which the sealing tape 59 is made preferably has good thermal conductivity.

A space is delimited from the circumference of the drying cylinder 3 and the sealing tape 59 guided over the drying cylinder 3, within which the material web 9 and — in the exemplary embodiment shown in FIG. 4 — the support tapes 5, 7 are arranged during their circulation over the drying cylinder 3. In a particularly preferred embodiment variant, it is provided that this space is sealed with the aid of a seal (not shown in FIG. 4) from the overpressure hood 27, which here only comprises a pressure space 29. Due to the complete sealing of the space from above by the sealing tape, from below by the drying cylinder and on the sides by the seal to the overpressure hood, penetration of the preferably liquid or gaseous medium, which serves to cool the sealing tape 59, and thus prevents moistening of the material web. In all of the exemplary embodiments, the drying section, in which such a sealing tape 59 is used, is preferably a space delimited on the sides by the circumference of the drying cylinder and the sealing tape itself. sealed with a seal against the pressure hood or its pressure chamber / pressure chambers. The design of the seal can be chosen arbitrarily.

In the embodiment shown in FIG. 1, the sealing tape 59 is cooled by the medium under pressure, which in turn cools the second support tape 7 which is in contact with the sealing tape 59. This results in a temperature gradient in the heated drying cylinder 3 in the direction of the sealing tape 59, which in turn leads to increased heat transfer from the drying cylinder 3 to the material web 9. The liquid, which partially emerges as vapor from the material web 9, penetrates the porous first support band 5 and preferably condenses as condensate in the second support band 7, which is cooler than the first support band 5, and is taken up by the latter.

As already described above, the contact pressure which presses the material web 9 onto the circumference of the drying cylinder 3 is composed of the forces generated by the pretensioning of the support belts 5, 7 and the gaseous medium under pressure. The size of the forces generated by the pretensioning of the support belts and the gas pressure or their share in the contact pressure can be chosen as desired, preferably adjusted, for example depending on the requirements placed on the material web to be produced. As can be seen from FIG. 4, the support tapes 5, 7 and the sealing tape 59 are guided over guide rollers 11 to 19, 61 and 21, which are arranged outside the overpressure hood 27. This ensures good accessibility to the guide devices of the belts, here the guide rollers. In addition, the structure of the pressure hood 27 can be simplified.

In the embodiment shown in FIG. 4, the sealing tape 59, the support tapes 5, 7 and the material web 9 are led out of the pressure chamber 29 through the nip in the outlet area 25 between the guide roller 21 and the drying cylinder 3. The material web 9 is guided further via a deflection roller 48 to a subsequent area of the paper making machine. The sealing tape 59 is guided directly from the guide roller 21 to the guide roller 19, while the support tapes 5, 7 are initially guided to the guide roller 61 and from there to the guide roller 19. In the area between the guide rollers 21 and 19 there is a blowing device 63 which acts on the support belts 5, 7 with a gaseous medium, as a result of which the liquid taken up by the support belts 5, 7 during the circulation around the drying cylinder 3 is blown out. The liquid is collected in a container 49 which is arranged on the material web side opposite the blowing device 63. Subsequently, the support tapes 5, 7 and the sealing tape 59 are brought together in the region of the guide roller 19 and guided together via the guide rollers 17, 15, 13 and 11 to the drying cylinder 3. In an advantageous embodiment, it is provided that the first support band 5, which has a fine structure, and the second support band 7, which has a coarser structure than the first support band 5, are connected to one another to form a support band, for example glued or woven. In another exemplary embodiment, the support tapes 5, 7 and the sealing tape 59 are connected to one another and form a single support / sealing tape. In a further embodiment it is provided that only the second support band 7 and the sealing band 59 are connected to one another. It is clear from everything that more than three tapes, for example four tapes, or two tapes, for example a support tape and a sealing tape, can be used, with which the functions of the support tapes 5, 7 and / or and the sealing tape 59 can be realized .

In the exemplary embodiments described with reference to FIGS. 1 to 4, the material web 9 lies directly on the outside or surface of the drying cylinder. In another embodiment it is provided that a screen belt is guided between the material web 9 and the drying cylinder 3. The adhesion of the moist material web 9 to the drying cylinder can be reduced by the sieve belt, so that it can be detached from the drying cylinder 3 relatively easily.

It is readily apparent that the exemplary embodiments of the overpressure hood described with reference to FIGS. 1 to 4 can also be used within a finishing machine, for example a coating machine. can be set. In an advantageous embodiment variant, a liquid, preferably water, is provided for cooling a strip, which is under a pressure of preferably 0.001 bar absolute to 12 bar absolute and is introduced into the pressure chamber 29.

To summarize, it can be stated that the drying of a dryer section can be increased by cooling the belt / belt and / or the material web 9 guided together with the material web 9 via the drying cylinder 3 and / or the material web 9 by means of the pressurized, preferably liquid or gaseous medium. It is particularly advantageous that existing dryer sections can be retrofitted relatively easily with the support tapes 5, 7 and / or the sealing tape 59.

In the following, further exemplary embodiments of an overpressure hood are explained in more detail with reference to FIGS. 5 to 7, specifically FIG. 5 shows a schematic illustration of a drying cylinder 101 in a front view. In this exemplary embodiment, only a support belt 103, for example a screen, is guided over a peripheral region of the drying cylinder 101 together with a material web 9, for example a paper web. In order to enlarge the contact area between the heated surface of the drying cylinder and the material web to be dried, deflecting rollers 107 are provided in the feed or run-up area and in the outlet area of the drying cylinder, the direction of rotation of which depends on the running direction depends on the material web and is indicated here by arrows.

The material web 9 is adjusted to improve the heat transfer from the drying cylinder 101 to the material web by means of a predetermined support belt tension. In order to improve the drying contact with the surface of the drying cylinder 101, a pressure device designed as an overpressure hood 111 is provided, which preferably extends over the entire length of the drying cylinder 101.

The overpressure hood 111 has a plurality of inner walls 113 and 115, which preferably extend over the entire length of the overpressure hood and which delimit a plurality, here three, overpressure chambers 117, 119, 121. In the overpressure chambers, a pressure level is set in a suitable manner, for example by supplying a gaseous medium, for example air, or preferably liquid medium, preferably water, on the basis of which the support band 103 and thus the material web 9 are pressed against the surface of the drying cylinder 101, so that there is an improved heat transfer. The pressure levels pi, p ₂ , p ₃ in the pressure chambers 117, 119 and 121 can be set to the desired values in order to ensure optimal drying behavior of the material web. The pressure levels can be set, for example, according to the inequality pi <p ₂ > p ₃ or according to the inequality i> p ₂ > p ₃ . In addition, the pressure chambers can be subdivided in the longitudinal direction, that is to say over the width of the material web 9, in order to be able to set different pressure values transversely to the running direction of the material web.

The longitudinal edges of the housing 123 of the overpressure hood 111 adjoining the surface of the drying cylinder 101, like the longitudinal edges of the intermediate walls 113 and 115 facing the peripheral surface of the drying cylinder 101, are provided with sealing strips 125, which largely prevent pressure loss from the overpressure chambers. So-called air knives can also be used instead of the sealing strips 125, as a result of which a contactless sealing of the overpressure chambers can be implemented. The housing 123 is also provided on the front side and on the opposite rear side with sealing strips 127, which are indicated here by dashed lines.

It is possible to adjust the pressure conditions of the overpressure hood 111 by the sealing behavior of the sealing strips 125 and 127. For example, a gentle pressure transition in the pressure chambers 117, 119 and 121 can be achieved in that the sealing strips 125 provided on the inner walls 113 and 115 enable a medium transition and thus pressure equalization. Likewise, when the material web 9 enters and exits the pressure hood, pressure equalization may be desired in order to ensure a smooth pressure transition here as well. Finally, it is also possible to design the sealing strip 127 provided on the front and rear of the housing 123 in such a way that pressure equalization is also possible here in order to achieve a smooth pressure transition. As a result, the edge of the material web 9 is pressed against the drying cylinder 101 with a lower contact pressure, which counteracts overdrying of the web edges.

FIG. 6 shows, in a highly schematic manner, the end face of a further exemplary embodiment of a drying section 110 which has a plurality of drying cylinders 101 lying next to one another. In the exemplary embodiment shown here, a pressure device designed as an overpressure hood 111 is assigned to each individual drying cylinder. The pressure hoods each have three pressure chambers 117, 119 and 121. The chambers are pressurized via lines 129 with a pressurized gaseous or liquid medium, the pressure medium being supplied via a first connecting line 131 at a pressure level pi, with which the pressure chambers 117 are acted upon. The middle pressure chamber 119 of the pressure hoods 111 is pressurized with a pressure level p ₂ via a second connection line 133. Finally, the pressure chambers 121 of the pressure hoods 111 are supplied with a pressure level p ₃ via a third connection line 135.

After all, it is clear that the same pressure level sequences pi, p ₂ and p _{3 are} supplied in all overpressure hoods, so that the same contact forces act everywhere. In the drying section 119 shown here, the support belt 103 and the material web 9 are guided in a meandering manner over drying cylinders 101, between which deflection rollers 107 are arranged in each case. An external suction box 137 is arranged between each two drying cylinders, with the aid of which the medium entrained by the material web is sucked off, but in particular guiding the material web is ensured.

FIG. 7 shows a schematic front view of a further exemplary embodiment of a drying section 110, of which four drying cylinders 101 are shown here purely by way of example. Deflection rollers 107 are again provided between each two drying cylinders, so that the support belt 103 and the material web 9 can be guided in a meandering manner over the drying cylinders 101. The tensile force of the support belt 103 presses the material web 9 against the heated surface of the drying cylinders. In addition, pressure devices designed as overpressure hoods 111 are again provided for each drying cylinder. However, the overpressure hoods here each have four overpressure chambers 117, 119, 119 'and 121, each of which is supplied with a pressurized, preferably liquid medium via separate pressure lines 139.

By marking the pressure levels Pi, p ₂ ... Pa,. , , in the various pressure chambers it is indicated in FIG. 7 that all pressure chambers of all pressure hoods 111 have a single genes, can have independent of the other pressure chambers pressure level. With such a configuration of the dryer section 110, it is thus possible to apply different contact forces along the running direction of the material web 9 and thus to ensure an individual drying behavior.

In the embodiment of the dryer section 110 shown in FIG. 7, suction boxes 137 are provided between each two drying cylinders 101. The suction boxes 137 are connected to a suitable negative pressure source, for example a vacuum pump, which is not shown in more detail here. The exhaust air from the suction boxes or the vacuum pump can be dried by downstream units and possibly heated and then fed to the pressure chambers.

From all this it is clear that the contact pressure can be set very variably. It has also been shown that even with a very low overpressure of, for example, 0.05 bar, an additional application of pressure is achieved, which roughly corresponds to a doubling of the maximum screen printing forces customary today. This means that the contact pressure can be increased very effectively with a contact pressure device designed as an overpressure hood.

It can be seen from the explanations for FIGS. 1 to 7 that the contact forces can be adjusted to the desired values not only over the circumference of the drying cylinders but also over their length are. This allows the heat transfer within the dryer section to be set individually. It is also possible to squeeze out an air cushion based, for example, on entrained air by setting a differential pressure rise at the inlet into the dry end and also thereby to have a positive influence on the drying properties by means of an improved heat transfer. This particular advantage can therefore be achieved without additional measures.

In the exemplary embodiments according to FIGS. 5 to 7, it is readily possible for the temperature of the medium, which is under pressure, preferably liquid, and which is introduced into the overpressure chambers 117, 119, 119 'and 121 to be lower than the temperature the outside of the partial circumference of the drying cylinder 101 which is wrapped by the material web and the at least one support band. This results in a temperature gradient from the heated drying cylinder 101 in the direction of the support band, as a result of which both the heat flow can be increased and the discharge direction of those emerging from the material web Liquid. Furthermore, it is possible for different pressure media to be introduced into the pressure chambers 117, 119, 119 'and 121, the temperature of the liquid or gaseous medium being able to vary from one pressure chamber to the next. As a result, a different heat flow can be set on the circumference of a drying cylinder. In an advantageous embodiment variant of the exemplary embodiments of the drying section explained with reference to FIGS. 5 to 7, it is provided that the material web 9 is guided together with at least two support bands and / or a medium-impermeable sealing band 9 over a peripheral region of one or more drying cylinders 101. The support bands can have different structures (coarse / fine). Furthermore, the support tapes can be connected to one another and / or the sealing tape, or one of the support tapes to the sealing tape.

From everything it is readily apparent that even in the case of an overpressure hood 27 described with reference to FIGS. 1 to 4, with suitable means, the pressure space 29 — viewed in the circumferential direction and / or in the longitudinal extent of the drying cylinder — can be subdivided into at least two pressure chambers, so that the same Set advantages as in the case of the overpressure hood 111 described with reference to FIGS. 5 to 7.

All of the exemplary embodiments have in common that the temperature of the medium introduced into the pressure chamber 29 or into the pressure chambers 117, 119, 119 'and / or 121 is lower than that on the outside of the drying cylinder, and that the medium is under a pressure which is preferably is in a range from 0.001 bar to 12 bar. A liquid pressure medium, in particular water, is particularly preferred, since a liquid — in comparison to a gas — can achieve a higher pressure with a lower flow. Through the resulting economic advantages can also reduce the cost of the dryer section.

The sealing tape 59 described above can be made of any material, preferably with good thermal conductivity. In an advantageous embodiment, the sealing tape consists of at least one metal, for example steel, which, among other things, has good strength properties in addition to good thermal conductivity.

In the following, further design variants of the dryer section are explained in more detail with reference to FIGS. The same parts are provided with the same reference numerals, so that reference is made to the description of the preceding Figures 1 to 7. The drying cylinders of the dryer section are each assigned, by way of example only, an overpressure hood 27 comprising a pressure chamber 29. Furthermore, in all of the exemplary embodiments, the material web 9 is guided together with first and second support tapes 5, 7 and a sealing tape 59 over a peripheral region of the drying cylinders. Of course, other guide variants described above are also possible, for example that the material web 9 is pressed onto the circumference of the drying cylinder by means of only a single support belt.

FIG. 8 shows a modified embodiment of the drying section 1 shown in FIG. 4. Only the differences are discussed in more detail below. In the embodiment shown in FIG. 8, which is compared to the embodiment shown in FIG. is rotated by 180 °, suction rollers 65a and 65b are provided, which are arranged at a relatively short distance from one another and each form a nip with the drying cylinder 3. The structure and the structural design of the suction rolls mentioned here are known per se, so that they are not described in more detail. The support belts 5, 7 and the material web 9 are passed through the nip formed by the suction rolls. The suction rolls 65a, 65b are assigned suction boxes 67a and 67b which can be acted upon by a vacuum and are arranged within the closed loop of the support belts 5, 7 and are constructed here essentially identically. The suction box 67a arranged in the space between the suction roll 65a and the guide roll 13 has a first, straight wall section 69 and a second wall section 70 which is adapted to the curvature of the suction roll and which can be vacuumed. In the area of the first wall section 69, over which only the support belts 5, 7 are guided, the material web brought up by a preceding part of the machine is sucked onto the first support belt 5 and together with the support belts via the suction roller 65a into the nip between the latter and the Drying cylinder 3 out.

Downstream of the suction roll 65a, viewed in the direction of travel of the material web, is a guide roll 11 which forms a nip with the drying cylinder 3 and over which the sealing tape 59 which is separate from the support belts 5, 7 in the region of the guide roll 13 is guided. In the nip between the guide roller 11 and the drying cylinder 3, the sealing tape 59 with the support bands 5, 7 and the material web 9 brought together, that is, before the material web and the bands are guided into the pressure chamber 29 of the pressure hood 27. After the material web 9 and the belts are guided over a circumferential region of the drying cylinder 3, which bears against it, to a guide roller 21 which forms a nip with the drying cylinder, the sealing belt 59 which bears against the second support belt 7 is separated therefrom and via guide rollers 19, 17 , 15 returned to the guide roller 13. The material web lying on the outer circumference of the drying cylinder 3 and the support belts 5, 7 are guided further to the outlet area 25, where they are then lifted off the drying cylinder 3 and deflected by the suction roller 65b. The material web and the support belts 5, 7 are guided together over a first, straight wall section 69 of the suction box 67b, which can be subjected to a vacuum at least in sections, in order to hold the material web on the first support belt. At the guide roller 61 arranged downstream of the suction box 67b, the material web is separated from the first support belt 5 and passed on to a subsequent device (not shown) of the machine (arrow 71), while the support belts 5, 7 are guided via the guide roller 61 to the guide roller 19 which is also the sealing tape 59 is performed. From the guide roller 19, the support belts 5, 7 and the sealing tape 59 resting on the second support belt 7 pass through the guide rollers 17 and 15 to the guide roller 13. In the area between the guide rollers 61 and 19, the two support belts 5, 7 are acted upon by a gaseous medium , so that the liquid which has emerged from the material web and is taken up by the support bands blown out here or is sucked off - in another, not shown embodiment.

With the aid of the guide device (suction box, roller) provided in the transfer area, in which the material web is transferred from a part of the machine upstream of the drying cylinder 3 to the support belts 5, 7 and transported to the run-up area 23, and the one in the run-off area 25 and that located thereon subsequent transfer area, in which the material web is continued on a downstream part of the machine, provided guide device (suction box, roller), good adhesion of the material web to the support belts 5, 7 and thus reliable guidance can be ensured. Due to the good adhesion of the material web to the support belts, the shrinkage of the material web during the drying process, which can lead to an undesirable material web cross profile, is also hindered. By using the devices that can be subjected to a negative pressure in the transfer and takeover area or run-up area 23 and drain area 25 of the drying cylinder 3, reliable guiding of the material web 3, in particular also by a device arranged upstream of the drying cylinder 3, can be ensured there even at high machine speeds. Instead of the suction boxes 67a, 67b, the suction rolls 65a, 65b can also be sucked from the outside through at least one of their bearing journals, not shown in FIG. In the exemplary embodiment shown in FIG. 8, a scraper 73 known per se is also provided, which is arranged in the space between the suction rolls 65a and 65b and which interacts with the outer surface of the drying cylinder 3. When the machine is started up or when the material web is torn off, the scraper 73 prevents the material web from being repeatedly drawn into the nip between the suction roller 65a and the drying cylinder 3. In this exemplary embodiment, the housing 28 of the overpressure hood 27 assigned to the drying cylinder 3 has both ends thereof each have a sealing strip 33 which can be pressed onto the sealing tape 59 guided around the outside of the drying cylinder 3 or cooperates with the latter without contact. As already described above, the sealing strips 33 serve to seal the pressure chamber 29 of the overpressure hood 27.

FIG. 9 shows part of a further exemplary embodiment of the drying section 1, which comprises a drying group 75, here comprising a total of four drying cylinders 3. The first and third drying cylinders 3, viewed in the direction of travel of the material web 9, form a first, lower drying unit 77 and are arranged at a distance from them below the second and fourth drying cylinders 3, which form a second, upper drying unit 77 '. An overpressure hood 27 is assigned to each of the drying cylinders 3, which purely by way of example have the same structure as the overpressure hood described with reference to FIG. The lower and upper drying units 77 and 77 'are first Support tape 5, a second support tape 7 and a sealing tape 59 or 5 ', 7' and 59 'assigned. Each of the drying cylinders 3 is assigned a suction roller 65a in the run-up area 23, which can be subjected to a vacuum from a suction box 67a arranged in the direction of travel of the material web. A suction roller 65b is provided in each of the outlet / outlet region 25 of the drying cylinder 3, wherein here, for example, the suction rollers 65b assigned to the first, second and third drying cylinders can be sucked through at least one of their bearing journals and the suction roller 65b assigned to the fourth drying cylinder with the aid of a suction box 67b. Modified types of suction are also possible.

The guidance of the support belts 5, 7 and 5 ', 7' are selected such that the material web 9 is guided in the transfer path between two drying cylinders 3 of the drying group 75 between the first support belt 5 of the drying unit 77 and the first support belt 5 'of the drying unit 77 , for example in the area of the straight section of the suction box 67a assigned to the second drying cylinder 3, over which the support tapes 5 ', 7' and the sealing tape 59 'of the overhead drying unit 77' are guided and the support tapes 5, 7 of the drying unit 77 below become.

Between the suction roller 65b assigned to the first drying cylinder and the guide device following in the web running direction and assigned to the second drying cylinder, here the suction box 67a the web guide closed. In connection with the present invention, a "closed" web guide is understood to mean that the material web 9 is transported from a guide device (roller, suction box or the like) to the subsequent guide device without the material web 9 having a free train or the at least one support belt , on which the material web lies, runs through a free running path. As can be seen from FIG. 9, the web guide is closed within the entire dryer group 75. In an embodiment variant not shown in the figures, it is provided that the connection between the guide devices of the individual drying cylinders or the drying units can be released or closed as desired. This makes it possible to protect the belts when starting up, i.e. when the machine is started up and in the event of faults. For this purpose, for example, the deflection / guide rollers designated by "B" in FIG. 9 are designed to be displaceable in a suitable manner.

In another exemplary embodiment of the drying group 75 shown in FIG. 9, this comprises only one or more than two drying units which are strung together. The drying cylinders of the drying group are arranged on an imaginary, preferably horizontal plane. This makes it possible for all support and sealing tapes of the drying group to be guided above or below the drying cylinder. The drying cylinders of the drying group 75 are preferably assigned only one set of the bands (support band / bands, sealing band). It is particularly advantageous in the exemplary embodiment shown in FIG. 9 that the guidance selected here for the support tapes 5, 7, 5 ', 7' and the sealing tapes 59, 59 'makes it possible for the water which has accumulated in the support tapes after each drying cylinder 3 can be blown out by a blowing device 63 which, as shown, can preferably be attached to the scraper 73 of the opposite drying cylinder of the other drying unit. For this purpose, the sealing tape is first separated from the support tapes, runs through a free running distance and is then placed directly on the next drying cylinder of the same drying unit.

The scrapers 73 are arranged in the space between the suction rolls 65a, 65b. In order to avoid undesired drawing of a damaged or torn material web into the drying cylinder in the event of malfunctions, further blowing devices 63 arranged in the area of the scrapers 73 are provided here. The air jets emerging from these additional blowing devices are marked with an "L". When the additional blowing device 63 (air jets L) is activated, the material web - for the most part between the first support belts 5, 5 '- is guided to an area of the drying group 75 marked "A", which is in the vicinity of the inlet and outlet area of the fourth drying cylinder 3 lies. In area "A", the material web is discharged downward from dryer section 1. The press 81 upstream of the dryer section 1 comprises rollers 83 and 84, between which a closed nip is formed. Press felts 85, 86 are also provided, between which the material web 9 is guided through the press nip. Thanks to the double felted press, the material web can be guided safely even at high machine speeds. Downstream of the press 81 is a suction box 87, which in sections is opposite the suction box 67a assigned to the first drying cylinder 3 of the drying group 75. As can be seen from FIG. 9, the press felt 85 is discharged downwards via a deflection roller 88 after the start of the suction box 87, while the upper press felt 86 and the material web 9 are guided over a straight section of the suction box 87 which can be subjected to a vacuum. The material web is sucked in by the latter in the area in which the suction boxes 87 and 67a overlap, so that it adheres to the support belts 5, 7 guided over the suction box 67a. It is clear from everything that the transfer of the material web from the press 81 to the first drying cylinder 3 can be carried out particularly safely and trouble-free with the aid of the suction boxes 87, 67a.

In FIG. 9, a section of a further embodiment of the drying section is shown on a larger scale within a dashed circular line, namely the transfer area between the press 81 and the first drying cylinder of the drying group 75. The sealing tape 59 is here via an additional deflection roller 90 to the guide roller 11 out before the support bands 5, 7 with the on the Press felt 86 adjacent material web 9 are brought together in the area of the suction boxes 87, 67a.

The drying section 1 shown in FIG. 9 is - seen in the direction of travel of the material web - a conventional, single-row dryer group 89 downstream in the closed web guide, which here comprises a plurality of drying cylinders, via which the material web 9 is guided in a meandering manner together with a support belt also referred to as a conveyor belt. After the last drying cylinder 3 of the drying group 75 has run off, the material web is guided over the straight section of the suction box 67b to the first drying cylinder 91 of the drying group 89. The web guide between the suction box 67b and the drying cylinder 91 is closed. In a further exemplary embodiment (not shown in the figures), the drying section 1 is followed by a conventional, two-row drying group (not shown in the figures), a closed connection of the drying group to the drying section 1 being also possible here for the safe transfer of the material web.

In order to reduce the rewetting of the material web 9 by means of the support belts 5 ', 7' which have been filled with water after the last drying cylinder of the drying group 75 has run out, before the material web is transferred from the last drying cylinder 3 of the drying group 75 to the first drying cylinder 91 of the drying group 89 the first support belt 5 ', which has a finer structure, is separated from the coarser, second support belt 7' in such a way that only the first support belt 5 'is used to transfer the material web 9 is applied. The second support belt 5 'can, for example, be brought together again with the support belt 7' and dried together with the support belt 7 'via a further guide roller, not shown in FIG. 9, in front of the blowing or suction device 63.

FIG. 10 shows part of a further exemplary embodiment of the dry group 75 shown in FIG. 9. The same parts are provided with the same reference symbols, so that reference is made to the preceding figures for description. In the exemplary embodiment shown in FIG. 10, straight transfer paths between the lower drying unit 77 and the upper drying unit 77 'are avoided, which is possible due to a smaller distance between the drying cylinders of the drying units 77, 77'. The suction roller 65b provided in / outflow region of the first drying cylinder, over which the support belts 5, 7 and the material web 9 are guided together, forms with the suction roller 65a provided in the run-up region of the second drying cylinder, over which the support belts 5 ', 7' of the drying unit 77 'are performed, a closed nip. The material web is here transferred from the drying unit 77 to the drying unit 77 'without the aid of a suction box. It can also be seen from FIG. 10 that the suction roller 65b provided in the outlet area of the second drying cylinder and the suction roller 65a provided in the opening area of the third drying cylinder likewise form a closed nip. In an advantageous embodiment it is provided that at least one of the suction rollers 65a and 65b which are adjacent to one another can be displaced, preferably pivoted, so that the connection between the two suction rollers, that is to say the nip, can be opened or closed. This makes it possible to protect the support belts when the machine is started up or in the event of an accident.

FIG. 11 shows an embodiment variant of the coupling between a press 81 arranged upstream of the dryer section 1, viewed in the direction of travel of the material web, which essentially differs from that in FIG. 9 only in that only one press felt 86 through the closed nip between the rollers 83, 84 is performed. The press felt 86 is first passed over a suction roll 94, on which the material web 9 is sucked onto the press felt 86. A deflecting roller 95 downstream of the press 81, over which the press felt 86 is guided, can be displaced purely by way of example in the direction of an arrow 96 and can be pressed against the circumference of a suction roller 97, over which the support belts 5 and 7 are guided. In the embodiment shown in FIG. 11, the nip between the movable deflecting roller 95 and the suction roller 97 can be closed, so that a closed web guide with reliable transfer of the material web from the press 81 to the support belts 5, 7 of the dryer section can be realized. A transfer with other known, appropriately designed devices is also possible before the nip is closed. Of course, it is also possible, for example, while the machine is running, for an open web guide, as shown in FIG. 11 is realized so that the tapes and the press felt are protected.

FIG. 12 shows a section of an embodiment of the drying section 1 that can be produced particularly cost-effectively, in which the material web 9 is transferred directly from the first drying cylinder of the drying section 1 or the drying group 75 to the second drying cylinder 3. Guide devices, for example guide rollers, suction boxes or the like, in the area between two drying cylinders are therefore not required. As shown in FIG. 12, there can be a small distance between the two drying cylinders 3, that is to say a short free draft, or else the drying cylinders lie against one another on their circumference under a preferably slight pressure. The arrangement of the other elements and devices of a dryer section is preferably unchanged. To transfer the material web 9 from the first drying cylinder 3 to the next, a scraper 73 and possibly also a blowing device, not shown in FIG. 12, are used.

All of the exemplary embodiments described with reference to the figures have in common that they can also be operated in such a way that a fine porous sieve, which preferably has a high thermal conductivity, is guided on both sides in direct contact with the material web. The web guidance can be simplified due to these additional screens. Suction rolls and suction boxes can be omitted where they are not required for feeding the material web onto a subsequent device. In this variant, the web guide in the transition from the press upstream of the dryer section and in the transition downstream of the machine section, for example to a conventional, single-row or double-row dryer group, must be modified in a suitable manner so that the additional screens at these points applied to the material web or separated from it and can be returned from the point of discharge to the point of contact of a cylinder.

In all of the exemplary embodiments shown in FIGS. 1 to 12, corresponding web guiding elements, for example wire or belt run regulators, tensioning devices, conditioning devices, transfer devices or additional blowpipes and scrapers are required, which are known per se and are therefore not shown.

In summary, it should be noted that in all of the exemplary embodiments of the drying section 1 and the drying group 75 described with reference to the preceding figures, the overpressure hood described with reference to FIGS. 1 to 7 can be assigned to the drying cylinders. The structural design of the overpressure hood is preferably adapted to the guidance of the material web 9, if provided the support bands 5, 7 and / or the sealing band 59. Each of the drying cylinders can be assigned its own set of belts (support tapes, sealing tape and the like) or else the belts are guided over several drying cylinders, such as in the exemplary embodiments shown in FIGS. 9 and 10.

Claims

Expectations

1. Drying section of a machine for the production and / or processing of a material web, in particular paper or cardboard web, with at least one heatable drying cylinder which is wrapped on part of its circumference by the material web and at least one support belt, and one with the drying cylinder pressurized hood or pressurized liquid or gaseous medium, characterized in that the temperature of the medium is lower than the temperature on the outside of the material web (9) and the support belt (5; 7; 103; 5 '; 7') Part of the drying cylinder (3; 101).

2. Drying section according to claim 1, characterized in that at least one further, second support belt (7; 7 ') is guided around the outside of the drying cylinder (3; 101).

3. Drying section according to claim 2, characterized in that the second support belt (7; 7 ') has a coarser structure than the first support belt

(5; 103; 5 ').

4. Drying section according to one of the preceding claims, characterized in that a medium impermeable sealing tape (59; 59 ') is guided around the outside of the drying cylinder (3; 101).

5. Drying section according to one of the preceding claims, characterized in that the first support tape (5; 103; 5 '), the second support tape (7; 7') and the sealing tape (59; 59 ') or the first support tape

(5; 103; 5 ') and the second support band (7; 7') or the second support band (7; 7 ') and the sealing band (59; 59') are connected to one another.

6. Drying section according to one of the preceding claims, characterized in that the material web (9) rests directly on the heated drying cylinder (3; 101).

7. Drying section according to one of claims 1 to 5, characterized in that between the web

(9) and drying cylinder (3; 101) a belt is guided.

8. Drying section according to one or more of the preceding claims, characterized by a plurality of drying cylinders (3a, 3b, 3c), to which an overpressure hood (27) is assigned and that in each case at least one band (support band (5; 7), sealing band ( 59)), preferably one and the same band (support band (5; 7), sealing band (59)) is guided.

9. Drying section according to one of the preceding claims 1 to 7, characterized by a plurality of drying cylinders, some of which, preferably all, are provided with an overpressure hood (27; 111) and that at least one belt (5,7,59,103), preferably one and the same belt (5,7,59,103), is guided over the drying cylinders.

10. Drying section according to one of the preceding claims, characterized in that the first support band (5; 103; 5 '), the second support band (7; 7') and / or the sealing band (59; 59 ') within the pressure hood (27 ) are / will be managed.

11. Drying section according to one of the preceding claims 1 to 9, characterized in that the first support band (5; 103; 5 '), the second support band (7; 7') and / or the sealing band (59; 59 ') between the

/ Drain area (23) in which the belts (5; 7; 59; 103; 5 '; 7') / the belt run from the drying cylinder (3; 101) and the run-up area (25) in which the belts / the belt runs onto the drying cylinder, is / will be guided outside the pressure chamber (29; pressure chamber (117; 119; 119 '; 121)) of the pressure hood (27; 111).

12. Drying section according to one of the preceding claims, characterized in that the pressure chamber (29; pressure chamber (117; 119; 119 '; 121)) of the pressure hood (27; 111) by means of seals (33,33') can be sealed from the environment .

13. Drying section according to claim 12, characterized in that the seals (33, 33 ') interact in a contactless or contacting manner with rollers (guide rollers (11, 21)) which act against at least one belt (5, 7, 59, 5', 7 ', 59', 103) and / or the material web (9) are pressed or are a short distance away from them.

14. Drying section according to one of the preceding claims, characterized in that the pressure hood (27; 111) from the end faces by means of the circumference, the end faces and / or journals of the drying cylinder (3) and the rollers cooperating covers can be sealed in a contactless or touching manner.

15. Drying section according to one of the preceding claims, characterized in that at least one roller (guide roller (11, 21)) can be pressed onto the drying cylinder.

16. Drying section according to one of claims 1 to 13, characterized in that at least one roller (guide roller (11, 21)) is arranged at a — preferably small — distance from the drying cylinder.

17. Drying section according to one of the preceding claims, characterized in that at least one seal (33, 33 ') interacts directly with the surface of a roller (55, 57 (guide roller (11, 21))).

18. Dryer section according to one of the preceding claims, characterized in that the material web (9) is guided into the pressure chamber (29) between two rollers (55, 57) arranged at a distance from one another or forming a nip.

19. Drying section according to one of the preceding claims, characterized in that the press nip formed between two rollers is formed by a shoe press.

20. Drying section according to one of the preceding claims, characterized in that the belt tension is adjustable.

21. Drying section according to one of the preceding claims, characterized in that the liquid or gaseous medium introduced into the pressure chamber (29; pressure chamber (117; 119; 119 '; 121)) is under a pressure which is in the range from 0.001 bar absolute to 12 bar absolute.

22. Drying section according to one of the preceding claims, characterized by a pressing device which presses the material web (9) onto the drying cylinder (101) and which is designed such that the pressing forces extend over subregions of the circumference and / or the width of the drying cylinder

(101) are of different sizes.

23. Drying section according to one of the preceding claims, characterized in that the pressing device is designed as an overpressure hood (111) which has zones which can be acted upon by different pressure values.

24. Drying section according to one of the preceding claims, characterized in that the zones are designed such that in the running direction and / or transversely different contact forces can be realized for the direction of travel of the material web (9).

25. Drying section according to one of the preceding claims, characterized in that the pressure hood (27; 111) with compressed air, dry air and / or steam or a liquid, in particular water, can be acted upon.

26. Drying section according to one of the preceding claims, characterized in that the pressure in the individual zones is variable.

27. Drying section according to one of the preceding claims, characterized in that the same pressure conditions are present in all overpressure hoods (111).

28. Drying section according to one of the preceding claims, characterized in that the zones with different pressure levels in an overpressure hood

(111) can be controlled independently of one another.

29. Drying section according to one of the preceding claims, characterized in that the overpressure hood (111) has at least two, preferably three to four, overpressure chambers which are arranged transversely to the direction of travel of the material web (9) and are sealed against one another and / or against the environment.

30. Drying section according to one of the preceding claims, characterized in that the seals (sealing strips (125, 127)) between the overpressure chambers and / or the environment are preferably a adjustable- allow air outlet to set a smooth pressure transition.

31. Drying section according to one of the preceding claims, characterized in that the sealing tape (59; 59 ') can consist of any materials / materials which preferably have good thermal conductivity.

32. Drying section according to claim 32, characterized in that the sealing tape (59; 59 ') consists of at least one metal, preferably steel.

33. Drying section according to one of the preceding claims, characterized in that the space delimited by the circumference of the drying cylinder and the sealing tape (59; 59 ') guided over the drying cylinder, within which the material web (9) and at least one support tape (5; 7; 5 '; 7') are arranged during their circulation over the drying cylinder and are sealed with the aid of a seal against the overpressure hood (27; 111) comprising at least one pressure chamber / one overpressure chamber.