Drying cylinder of a machine for producing a fibrous web

Abstract

Drying cylinder (1) of a machine for producing a fibrous web (6), comprising a casing (15) which rotates during operation of the machine, and alternative heating means (8) which are designed such that they can at least indirectly heat the casing (15) and the fibrous web (6) in order to dry the fibrous web (6), and wherein a plurality of openings (9) are arranged in the casing (15) of the drying cylinder (1), which openings connect an interior of the drying cylinder (1) with an exterior of the drying cylinder (1), so that an air stream from the interior of the drying cylinder (1) can flow through the openings (9), which just overlap with a removal area (AB) of the drying cylinder (1), in order to facilitate the removal of the fibrous web from the drying cylinder (1).

Description

The invention relates to a drying cylinder of a machine for producing a fibrous web, in particular a paper board web or tissue web, wherein the drying cylinder comprises means for heating the drying cylinder. Such drying cylinders are arranged in the drying section of machines for producing a fibrous web, wherein the drying section can be divided into a plurality of drying groups. Each drying group can then comprise a plurality of drying cylinders.Conventional drying cylinders are heated by means of hot steam. Drying cylinders with alternative heating means have long been known from the prior art, but have not gained acceptance in practice. For example, DE 1 151 724 B published in 1963 discloses a drying cylinder which is electrically inductively heated.The object of the invention is to provide a drying cylinder with alternative heating means which ensures, by a synergistic effect, that the associated machine for producing a fibrous web can be operated at a higher web speed than conventional machines, wherein the risk of web breakage is also reduced.The object is achieved according to the invention by an embodiment according to the independent claim. Further advantageous embodiments of the present invention are found in the dependent claims.The invention is explained below with reference to figures. The figures show in detail: FIG. 1 : Drying group FIG. 2 : Drying cylinder according to the prior art FIG. 3 shows a general structure of a drying cylinder according to the invention FIG. 4 : Means according to the invention for generating an air flow in a first embodiment FIG. 5 : Means according to the invention for generating an air flow in a second embodiment FIG. 6 : Means according to the invention for generating an air flow in a further embodiment FIG. 7 : Means according to the invention for generating an air flow in a further embodiment FIG. 8 : Means according to the invention for generating an air flow in a further embodiment FIG. 9 : Means according to the invention for generating an air flow in a further embodiment FIG. 10 : Alternative heating means according to the invention in a first embodiment FIG. 11 : Alternative heating means according to the invention in a second embodiment FIG. 12 : Alternative heating means according to the invention in a further embodiment FIG. 13 : Alternative heating means according to the invention in a further embodiment FIG. 14 a : Alternative heating means according to the invention in a further embodiment FIG. 14 b : Alternative heating means according to the invention in a further embodiment FIG. 15 : Alternative heating means according to the invention in a further embodimentFIG. 1 shows a schematic representation of, by way of example, a drying group as is used in multiple variations in machines for producing a fibrous web. Generally, such drying groups comprise at least one drying cylinder, at least one suction deflection roller, an air-permeable drying wire guided over the at least one drying cylinder and the at least one suction deflection roller, and at least one stabilization device. The drying group shown in Fig. 1 comprises five drying cylinders, one of which is designated 1, five suction deflecting rollers, one of which is designated 2, five stabilizing devices, one of which is designated 3, and a drying wire, which is designated 4. The machine direction is indicated by the arrow marked MD.FIG. 2 shows a drying cylinder 1 according to the prior art. FIG. 2 also shows two suction deflecting rollers 2, wherein a first suction deflecting roller 2 is arranged in front of the drying cylinder 1 in the machine direction and a second suction deflecting roller 2 behind the drying cylinder 1. FIG. 2 also shows the stabilizing device 3 associated with the second suction deflecting roller. The interior thereof is heated with steam. The vapor condenses on the inner surface of the drying cylinder shell and transfers the condensation energy to the drying cylinder shell, causing it to heat up. The condensate is continuously discharged from the drying cylinder. In the illustration of Fig. 2, two points FL and AL are marked on the drying cylinder jacket, which points stand for lines on the outer surface of the drying cylinder jacket. The line marked FL represents the "capture line" on which the fibrous web first touches the relevant drying cylinder jacket. The line marked AL represents the "take-off line" on which the fibrous web is taken off the relevant drying cylinder jacket. The take-off line AL is defined in this manner for ideal conditions, i.e. for the ideal case where the fibrous web follows the dryer fabric perfectly. In reality, however, the conditions are more complicated. Particularly in the case of drying cylinders which are arranged far in front of the drying section, the fibrous web which is still relatively moist there tends to adhere to the surface of the drying cylinder jacket. In order to clarify this, the relevant region (i.e. the region drawn by the dashed circle) has been shown in enlarged form. The enlargement of the jacket of the drying cylinder is shown shaded. The dryer screen is indicated by the dashed line. The fibrous web (shown as a solid line) is still directly located at the top right between the dryer wire and the surface of the dryer cylinder. To the bottom left, the dryer fabric lifts from the surface of the dryer cylinder, while the fibrous web still follows a stretch of the surface of the dryer cylinder jacket and only then lifts from the same and returns to the dryer fabric. In the following, the term "removal region AB" is understood to mean this entire region in which, under normal conditions (i.e. not during web break), the fibrous web follows the surface of the drying cylinder jacket, while the drying wire has already lifted from the latter. This region is marked in the enlargement by the double arrow. In any case, the decreasing line AL belongs to the decreasing range AB.In order to assist the detachment of the fibrous web from the drying cylinder, a suction region is arranged between the relevant drying cylinder 1 and the following stabilization device 2, which suction region is denoted by 5 in FIG. 2 and which provides a vacuum by means of which the fibrous web is sucked in and lifted off the surface of the drying cylinder. Further support is provided by the separation process by the centrifugal forces acting on the fibrous web and by tensile forces in the fibrous web itself. Since for reasons of energy efficiency and cost-effectiveness the vacuum of the suction region cannot be amplified as desired, and since there are also limits to the tensile forces in the fibrous web, when these forces are exceeded, there is a risk of web break (the centrifugal forces play only a minor role), in conventional drying cylinders the web speed must be limited in such a way that the detachment process can take place reliably under the conditions mentioned.The inventors have recognized that by using alternative heating means, a drying cylinder can be modified in such a way that the detachment process can be additionally supported thereby, so that the risk of web break can be reduced and the web speed can be increased. For this purpose, the inventors propose making the cylinder jacket perforated. The detachment process is decisively facilitated solely by the openings in the cylinder jacket, since air can flow through the openings from the interior of the drying cylinder into the removal region. Without such passive ventilation of the take-off area, the tendency of the fibrous web to remain adhering to the drying cylinder jacket is much greater. The detachment process can be further improved by providing for active ventilation of the removal region. To this end, the inventors propose to provide means for creating an air flow directed from the inside of the drying cylinder through the openings therein to at least a part of the take-off area AB.In this document, the term "alternative heating means" is understood to mean all heating means which are described in the document as being compatible with the invention. This term also includes all other known heating means which are suitable for heating a perforated drying cylinder jacket in order to dry the circulating fibrous web according to the invention. This does not of course include the steam heating described above, since the use of the same with a perforated drying cylinder jacket would instead lead to the fibrous web being moistened by the steam or by condensate.FIG. 3 shows the general structure of a drying cylinder according to the invention in a highly schematic illustration. The drying cylinder comprises a plurality of openings which are arranged in the jacket of the drying cylinder and connect the interior of the drying cylinder to the surrounding exterior. One of the openings is designated 9. The fibrous web is indicated by the solid line which wraps around the drying cylinder and is denoted by 6. For better visibility, this line is shown at a distance from the surface of the drying cylinder. The dryer screen is indicated by the dashed line which is denoted by 4. This line is also shown at a distance from the fibrous web for clarification. The drying cylinder according to the invention can furthermore advantageously comprise means for generating an air flow, wherein the means are designed such that an air flow is produced which is directed from the inside of the drying cylinder through the openings in the same onto at least a part of the removal region AB, which adjoins the removal line AL marked in the figure. In this case, the generated air flow can also flow through further regions. In other words, the means 7 for generating an air flow are designed such that during operation of the machine at least a part of the generated air flow can flow from the interior of the drying cylinder 1 through the openings 9 which just overlap with the removal region AB of the drying cylinder 1. The term "overlap" is also understood to mean only partial overlap.In FIG. 3, the means for generating an air flow are only indicated quite schematically by the rectangle designated 7. How the air flow is thereby produced in the individual embodiments according to the invention is described below in connection with FIGS. 4 to 9. The drying cylinder according to the invention further comprises alternative heating means for heating the jacket of the drying cylinder to dry the fibrous web. The alternative heating means are also indicated very schematically in FIG. 3 by the rectangle denoted by 8. The different embodiments of the alternative heating means will be described in connection with Figs. 10 to 13.FIG. 4 shows a first embodiment of the means 7 according to the invention for generating an air flow. To this end, the means 7 for generating an air flow comprise at least one blower or other source of compressed air connected to the interior of the drying cylinder, In Figure 4, the source of compressed air is indicated by 14, and the connection thereof to the interior of the drying cylinder is indicated by the curved dotted line. The connection of the one or more compressed air sources to the interior of the drying cylinder can advantageously be effected by the pins of the drying cylinder. As a result, an overpressure forms in the interior of the drying cylinder, which in turn leads to the air in the interior of the drying cylinder flowing outwards through the openings, insofar as these are not covered by any obstacles. This is indicated in FIG. 4 by the radially outwardly directed arrows. In the region in which the fibrous web does not lie against the drying cylinder, this is best achieved, which is indicated by the longer arrows in this region. Whether or how well the air can escape through the openings in the remaining region depends on the air permeability of the respective fibrous web. FIG. 4 shows the case that the air permeability of the fibrous web is comparatively high, which is the case, for example, with tissue fibrous webs. It is advantageous if the (dry) air of the air stream is heated, so that the fibrous web is dried by the hot air which flows through the fibrous web. In this case, the at least one source of compressed air 14 and at least a part of the alternative heating means advantageously form a unit, e.g. a suitable hot air blower.FIG. 5 shows the embodiment of FIG. 4, which is modified in that the drying cylinder comprises a cover which covers, on the inside of the drying cylinder, a part of the region at which no fibrous web is located on the outside. At these points, the outflowing air would have the least positive effect. The cover is designated 10. The cover prevents or complicates air from escaping through a major part of those openings which are not covered by the fibrous web. On the right side of the cover 10, the cover 10 leaves the openings located in the take-off area AB. By means of radially extending walls arranged on the right and on the left, the central part of the cover is offset radially inward. The right wall of the cover 10 forms a stagnation edge at which the air entrained by the rotating drying cylinder jacket jams, which leads to an advantageous amplification of the air flow in the removal region AB. In this embodiment too, the fans could be designed as hot air fans.The cover 10 could also be designed differently. Thus, the cover 10 could be arranged flat along the inner wall of the drying cylinder, both radial walls being omitted. It would also be possible to dispense with only the left radial wall, with the central part of the cover 10 increasingly conforming to the inner wall of the drying cylinder. The cover 10 could also extend flat on the inner wall in its entire region and be connected on the right side to a baffle plate as shown in FIG. 6. The cover 10 could be arranged on the outside of the drying cylinder. From the foregoing, the skilled person can easily find further suitable embodiments for the cover plate 10 without having to perform the inventor. In any case, the cover plate 10 rests with respect to the rotating jacket of the drying cylinder.In the embodiment shown in FIG. 6, the means 7 for generating an air flow comprise only one baffle plate, which has been designated 11. The air entrained by the rotating drying cylinder jacket accumulates on the accumulating plate 11 and is directed by the accumulating plate 11 onto the or a part of the removal region AB.This embodiment is particularly advantageous because it is of very simple construction and does not consume any additional energy. The baffle 11 also rests with respect to the rotating jacket of the drying cylinder. The baffle 11 from FIG. 6 and the cover 10 with the baffle edge from FIG. 5 are also referred to as baffle elements. The embodiment shown in Fig. 6 can be combined with the embodiment of Fig. 4.FIG. 7 shows an embodiment in which the means 7 for generating an air flow comprise a blow box which is arranged on the outside of the drying cylinder in the region in which no fibrous web runs. The blow box is designated 12. The interior of the blow box is connected to at least one source of compressed air 14. Through the openings in the jacket of the drying cylinder, the air flows from the blow box 12 into the interior of the drying cylinder. From there, the air can again pass through the openings into the outer space, provided that the openings are not covered. In order to avoid incorrect flows, it is advantageous if the blow box is sealed off from the environment by suitable seals. In FIG. 7, the arrows indicate the flow conditions that occur when the fibrous web offers a strong obstacle to an air flow. Then the air can only escape through the openings at those locations which are not covered by the fibrous web or the blow box. This includes in any case the region around the removal line AL or around the removal region AB. Since in the embodiment shown the openings on the other side of the blow box are covered by an additional (optional) cover, which is designated 10, the air cannot escape here. In this embodiment too, the blower could be designed as a hot air blower, which would be advantageous in particular if the fibrous web were not as strong an obstacle to the air flow as assumed in FIG. 7. The embodiment shown in FIG. 7 can be combined with a baffle plate.FIG. 8 shows an embodiment in which a blow box 12 is arranged in the interior of the drying cylinder in such a way that at least a part of the removal region AB is subjected to the flow of air through the latter. The blow box 12 is in turn connected to a compressed air source 14, which could also be designed as a hot air blower. In order to avoid incorrect flows, it is advantageous if the blow box is sealed off from the environment by suitable seals.FIG. 9 shows an embodiment in which a blow pipe 13 is arranged inside the drying cylinder in such a way that at least a part of the removal region AB is subjected to the flow of air through the blow pipe. The blow pipe 13 is in turn connected to a compressed air source 14, which could also be designed as a hot air blower.The figures described below relate to the alternative heating means. In this case, the alternative heating means can corotate or not corotate with the drying cylinder. In the latter case, the alternative heating means may be stationary or moved relative to the drying cylinder. Such a relative movement can consist, for example, in a periodic movement of the alternative heating means transversely to the machine direction. This may be advantageous in order to avoid streaking. In certain applications, profilings of the fibrous web may be just desired. In order to force these, the alternative heating means can be divided transversely to the running direction of the fibrous web. In order to avoid the formation of stripes, on the other hand, it is advantageous if the alternative heating means are formed without partitions in the transverse direction. With the drying cylinder, only embodiments of alternative heating means can be co-rotated, which are arranged inside the drying cylinder. For uniform heating, in this case the heating means must be arranged uniformly distributed over the entire cylinder jacket. In electrically powered heating means, the current can be transmitted to the rotating system through slip rings. The alternative is preferred in which the alternative heating means are stationary, since the same requires the least technical outlay. Therefore, all alternative heating means shown in the figures, which are arranged inside the drying cylinder, are designed as stationary heating means.Fig. 10 shows a first embodiment of the alternative heating means 8 according to the invention. The heating means or heating elements are designed such that they can heat the jacket of the drying cylinder. The heating means advantageously extend over the major part of the area of the jacket of the drying cylinder which is covered by the fibrous web. The heating means or heating elements can be designed to be air-impermeable, so that no air can flow outward in the radial direction through the same, or have openings through which air can flow radially outward and further through the openings in the jacket of the drying cylinder into the outer space. The second possibility is advantageous if the fibrous web is to be additionally dried over a large area by a stream of hot dry air, as in FIGS. 4 and 5. If the heating means are designed to be air impermeable, they can serve to cover the openings in the jacket and to concentrate the air flow onto the removal region AB. It is then advantageous if the heating means cover the entire jacket, with the exception of at least a part of the removal region AB (cf. FIG. 11 ). If the heating means are to be combined with the embodiments according to Figures 6, 7, 8 or 9, then the heating means must leave enough space to not interfere with the elements of the means for generating an air flow arranged inside the drying cylinder. The arrangement shown in FIG. 10 in conjunction with air-impermeable heating means can be combined particularly well with the embodiments according to FIGS. 7, 8 or 9, the cover 10 in FIG. 7 being omitted, since the heating means according to FIG. 10 already cover this region. The fact that the heating means also heat the region of the jacket which comes into contact with the fibrous web only a short time later has the advantage that the jacket is already heated at the time of contact. A combination with the arrangement according to FIG. 6 is less advantageous, since the heating means 8 in FIG. 10 prevent or greatly complicate entrainment of the air in front of the baffle plate 11. The compatibility can be improved by arranging the heating means 8 offset radially inward, so that a sufficiently large intermediate space is formed between the heating means 8 and the inner side of the cylinder jacket. The increase in the distance between the cylinder jacket and the heating means 8 can, however, lead to a reduction in the heating power.Fig. 11 shows an embodiment in which the heating means 8 comprise different heating elements. The embodiment shown here represents only a simple example with two different heating elements. In principle, the heating means 8 can comprise any number of different heating elements. In Fig. 11, the heating means comprise a first heating element, indicated 8.1, and a second heating element, indicated 8.2. The heating elements may differ in a variety of ways. One difference may be that the various elements are separated from each other, as indicated in FIG. 11. A further difference can consist in the fact that the different heating elements are operated with different heating power, as indicated in FIG. 11. A further difference can be that the heating elements differ with regard to their air permeability. Thus, in FIG. 11, for example, the heating element 8.1 could be air-permeable in order to allow the fibrous web to be dried by hot air, while the heating element 8.2 is designed to be air-impermeable in order to cover openings which are not covered by the fibrous web. A further difference may be that the different heating means are of different types. In this document, this is understood to mean the physical principle on which the heating effect of the relevant heating elements is based. The various types of heating means are described in more detail below.Fig. 12 shows an embodiment in which the heating means 8 are arranged on the outside of the drying cylinder. External heating elements can be combined with internal heating elements without problems. In Fig. 12, the heating means 8 are arranged in the area of the drying cylinder jacket which is covered by the fibrous web. Depending on the type of heating medium used, not only the drying cylinder jacket but also the fibrous web is directly heated.FIG. 13 shows an embodiment with several different heating elements, which are arranged on the outside of the cylinder jacket. The same applies to heating elements arranged on the outside, as was stated above in connection with FIG. 11 with heating elements arranged on the inside. As an example shown in Fig. 13 comprises two external heating elements 8.1 and 8.2, the heating element 8.2 being arranged in the area of the drying cylinder jacket which is not covered by the fibrous web. External heating elements can be combined without problems with the embodiments of the means for generating an air flow shown in FIGS. 4 to 9. For example, the heating element 8.2 from FIG. 13 could be integrated into the blow box 12 from FIG. 7. For this purpose, the heating element 8.2 is designed to be air-permeable.Drying cylinders can comprise support rings in the interior, which are used in particular in drying cylinders with a thin jacket. FIGS. 14 aand 14 b show how heating elements according to the invention can be formed in the region of such support rings. The figures each show a section of a drying cylinder according to the invention in a section parallel to the drying cylinder axis. The jacket of the drying cylinder is designated by 15. Connected to the inside of the jacket 15 is a support ring, which is designated 16. In FIG. 14a, a heating element 8.1 extends inside the drying cylinder beyond the support ring 16. In order that the jacket 15 and the support ring 16 can move freely relative to the heating element 8.1, a sufficiently wide intermediate space extends between the jacket 15 and the support ring 16 on the one hand and the heating element 8.1 on the other hand. For the support ring 16, the heating element 8.1 has a recess for this purpose. The arrangement shown in FIG. 14a can result in the temperature of the jacket 15 being somewhat lower in the region of support rings 16 than in the other regions of the jacket 15. The arrangement shown in FIG. 14 bdiffers in that a plurality of heating elements are provided in order to heat the region shown. A first heating element, indicated 8.1, extends on the left as far as the support ring 16, which extends somewhat further into the interior of the drying cylinder than in FIG. 14a. A second heating element, which is denoted by 8.2, extends on the right side as far as the support ring 16. A third heating element, which is denoted by 8.3, extends between the two heating elements 8.1 and 8.2 and connects the two heating elements 8.1 and 8.2 to one another mechanically and optionally electrically or with heating media technology. The third heating element 8.3 is designed in such a way that it can directly heat the support ring 16 and indirectly heat the jacket 15 via the latter.The heating means may be of the following types. In a first type of heating element, the heating energy is provided by the combustion of a fuel, for example by the combustion of gas. In a further type of heating elements, the heating energy is generated inductively in the cylinder jacket and in the support rings (if present). These elements must comprise a material suitable for induction. In a further type of heating elements, the heating energy is provided by infrared radiation. In a further type of heating elements, the heating energy is provided by an effect which is based on the principle of action of an eddy current brake. That is to say, the heating elements provide a static magnetic field which penetrates the cylinder jacket or the support rings. Due to the relative movement of the cylinder jacket or the support rings with respect to the magnetic field, eddy currents are induced in these elements, which heat these elements. For this purpose, these elements must comprise conductive material. In this case, the energy required for heating is provided by the drive of the drying cylinder, which must be designed to maintain the movement of the drying cylinder counter to the braking action of the heating elements. In a further type of heating elements, the heating heat is generated by microwave radiation. For this purpose, the relevant lateral surface (inside and / or outside) of the drying cylinder or the surface of the supporting rings is covered with a microwave absorber. The microwave absorber forms a part of the cylinder jacket or of the support rings. If the heating elements thus formed are arranged on the outside in the region of the cylinder jacket which is covered by the fibrous web, then a portion of the microwave radiation is absorbed in the fibrous web and heats the fibrous web directly. Experience shows, however, that this direct heating proportion is rather low. Another type of heating means has already been described above (hot air blower). A hot air blower also heats the fibrous web directly. In a further type of heating elements, the heating energy is provided by electrical heating elements, as in a heating ceiling. This type of alternative heating means is arranged inside the drying cylinder and rotates therewith.In general, it can be said that the alternative heating means are designed such that they can heat the jacket and the fibrous web at least indirectly in order to dry the fibrous web.Fig. 15 shows another embodiment of the drying cylinder according to the present invention. The drying cylinder comprises means for blowing open the openings. The means for blowing free the openings are formed in FIG. 15 as a blowing tube which is arranged in the interior of the drying cylinder and is formed such that it can blow free the openings from the inside to the outside. The blow pipe is denoted 17. The means for blowing free the openings could also be designed as a blow box. In order to prevent the material blown out of the openings from passing between the fibrous web and the drying cylinder, it is advantageous if a scraper is arranged on the outside of the drying cylinder in the direction of rotation behind the means 17, which scraper removes this material from the drying cylinder (not shown in FIG. 15 ).List of reference characters1 Drying cylinder 2 Suction deflection roller 3 Stabilizing device 4 Drying wire 5 Vacuum region 6 Fibrous web 7 Means for generating an air stream 8 Alternative heating means or heating element 8.1 Heating element 8.2 Heating element 8.3 Heating element 9 Opening 10 Cover 11 Baffle plate 12 Blow box 13 Blow pipe 14 Blower, hot air blower or compressed air source 15 Jacket 16 Supporting ring 17 Means for blowing open the openings AB Removal region AL Removal line FL Collecting lineReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 1 151 724 B

[0002]

Claims

Drying cylinder (1) of a machine for producing a fibrous web (6) comprising a jacket (15) which rotates during operation of the machine, and alternative heating means (8) which are designed such that they can heat the jacket (15) and the fibrous web (6) at least indirectly in order to dry the fibrous web (6), characterized in that a plurality of openings (9) are arranged in the jacket (15) of the drying cylinder (1), said openings connecting an interior space of the drying cylinder (1) to an exterior space of the drying cylinder (1) such that an air stream from the interior space of the drying cylinder (1) can flow through the openings (9) which overlap just with a removal region (AB) of the drying cylinder (1) in order to facilitate removal of the fibrous web from the drying cylinder (1).Drying cylinder (1) according to claim 1, wherein the drying cylinder (1) comprises means (7) for generating an air flow, and wherein the means (7) for generating an air flow are designed such that during operation of the machine at least a part of the generated air flow can flow from the interior of the drying cylinder (1) through the openings (9) which just overlap with a removal region (AB) of the drying cylinder (1).Drying cylinder (1) according to claim 2, wherein said means (7) for generating an air flow comprise at least one source (14) of pressurized air connected to the interior of said drying cylinder (1).Drying cylinder (1) according to claim 3, wherein the means (7) for generating an air flow comprise a cover (10) which covers at least a part of an area of the jacket (15) at which no fibrous web is located on the outside during operation of the machine.Drying cylinder (1) according to one of the preceding claims, wherein the means (7) for generating an air flow comprise a ram element (11, 10), on which during operation of the machine the air entrained in the interior of the drying cylinder by the jacket (15) is rammed and can be directed onto at least part of the removal region (AB).Drying cylinder (1) according to one of claims 2 or 5, wherein the means (7) for generating an air flow comprise a blow box (12) and at least one compressed air source (14), and wherein the blow box (12) is arranged on the outside of the drying cylinder (1) in a region of the jacket (15) at which no fibrous web (6) is located during operation of the machine, and wherein the compressed air source (14) is connected to the interior of the blow box (12).Drying cylinder (1) according to one of claims 2 or 5, wherein the means (7) for generating an air flow comprise a blow box (12) and at least one compressed air source (14), and wherein the blow box (12) is arranged inside the drying cylinder (1) such that at least a part of the removal region (AB) can be supplied with air through the blow box (12), and wherein the compressed air source (14) is connected to the interior of the blow box (12).Drying cylinder (1) according to one of claims 2 or 5, wherein the means (7) for generating an air flow comprise a blowing pipe (13) and at least one compressed air source (14), and wherein the blowing pipe (13) is arranged inside the drying cylinder (1) such that at least a part of the removal region (AB) can be supplied with air through the blowing pipe (13), and wherein the compressed air source (14) is connected to the interior of the blowing pipe (13).Drying cylinder (1) according to one of the preceding claims, wherein the alternative heating means (8) comprise at least one heating element (8, 8.1, 8.2, 8.3) which is arranged in the interior of the drying cylinder (1).Drying cylinder (1) according to claim 9, wherein the alternative heating means (8) comprise at least one heating element (8, 8.1, 8.2) arranged on the outside of the drying cylinder (1).Drying cylinder (1) according to claim 9 or 10, wherein the heating elements (8, 8.1, 8.2, 8.3) are designed to be impermeable to air or permeable to air.Drying cylinder (1) according to one of claims 9 to 11, wherein heating energy can be provided in at least one heating element by the combustion of a fuel.Drying cylinder (1) according to one of claims 9 to 12, wherein heating energy can be provided by induction in at least one heating element.Drying cylinder (1) according to one of claims 9 to 13, wherein heating energy can be provided by infrared radiation in at least one heating element.Drying cylinder (1) according to one of claims 9 to 14, wherein heating energy can be provided by eddy currents in at least one heating element.Drying cylinder (1) according to one of claims 9 to 15, wherein heating energy can be provided by microwave radiation in at least one heating element.Drying cylinder (1) according to one of the preceding claims, wherein the compressed air source (14) is designed as a hot air blower.Drying cylinder (1) according to any one of the preceding claims, wherein the drying cylinder (1) comprises means (17) for blowing free the openings (9) arranged inside the drying cylinder (1).

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