DRYING HOOD, DRYING ARRANGEMENT AND USE THEREOF

Abstract

A drying hood for drying a fibrous web, such as a tissue paper web, includes a plurality of nozzle boxes for supplying or discharging air and a housing that at least partially surrounds the nozzle boxes. The nozzle boxes are each individually mounted on the housing by a first bearing and a second bearing. The two bearings allow at least one movement of the nozzle box relative to the housing along a longitudinal axis of the nozzle box and/or at least one movement in a direction transverse thereto, along a transverse axis of the nozzle box. The two bearings have translational degrees of freedom differing by one. A drying arrangement having a drying cylinder and the drying hood is also provided.

Claims

1-15. (canceled)

16. A drying hood for drying a fibrous web or a tissue paper web, the drying hood comprising: a plurality of nozzle boxes for supplying or discharging air, each of said nozzle boxes having a longitudinal axis and a transverse axis being transverse to said longitudinal axis; a housing at least partially surrounding said nozzle boxes; first and second bearings, a respective one of said first bearings and a respective one of said second bearings individually mounting each of said nozzle boxes on said housing; said first and second bearings allowing at least one movement of said nozzle boxes relative to said housing along at least one of said longitudinal axis or said transverse axis; and said first and second bearings having translational degrees of freedom differing from one another by one degree of freedom.

17. The drying hood according to claim 16, wherein said first bearings have two translational degrees of freedom, and said second bearings have one translational degree of freedom.

18. The drying hood according to claim 17, wherein said first bearings permit a movement of said nozzle boxes relative to said housing in said longitudinal direction and in said transverse direction, and said second bearings permit a movement of said nozzle boxes relative to said housing in said transverse direction.

19. The drying hood according to claim 17, wherein: said first bearings are doubly displaceable and are configured to permit displacement of said nozzle boxes relative to said housing along said longitudinal axes of said nozzle boxes and along said transverse axes; and said second bearings are configured to be singly-displaceable bearings allowing displacement of said nozzle boxes relative to said housing along said transverse axis.

20. The drying hood according to claim 16, wherein said first and second bearings are linear bearings or pure linear bearings.

21. The drying hood according to claim 16, wherein said nozzle boxes have axial ends, and said first and second bearings mounting a respective one of said nozzle boxes are each disposed in a region of a respective one of said axial ends.

22. The drying hood according to claim 16, wherein said housing and said nozzle boxes have end faces facing each other, and said first and second bearings mounting a respective one of said nozzle boxes are each disposed in a region of a respective one of said end faces.

23. The drying hood according to claim 16, wherein said first and second bearings are each configured as a respective guide rail including a groove and a bolt engaging in said groove, said grooves are associated with said housing and said bolts are each associated with a respective nozzle box or bounded or formed by said respective nozzle box.

24. The drying hood according to claim 23, wherein each of said bolts has a rotationally symmetrical outer contour, and each of said grooves is a straight longitudinal groove formed to be complementary to said bolt engaging in said longitudinal groove.

25. The drying hood according to claim 23, wherein said bolt of at least one of said first or second bearings has an axial end facing said housing and being connected to or connectable to said housing by a force-locking, form-locking or material connection.

26. The drying hood according to claim 25, wherein said bolt of at least one of said first or second bearings has an axial end facing a respective one of said nozzle boxes and engaging said groove associated with said respective one of said nozzle boxes.

27. The drying hood according to claim 16, which further comprises at least one linear stop being associated with or formed by said first bearing and forming a defined gap between end faces of said housing and said nozzle box facing each other.

28. The drying hood according to claim 16, wherein said first and second bearings are sliding bearings.

29. A drying arrangement for drying a fibrous web or a tissue paper web, the drying arrangement comprising: a drying cylinder; and a drying hood according to claim 16 at least partially surrounding said drying cylinder.

30. The drying arrangement according to claim 29, wherein said drying cylinder has an outer circumference, and said plurality of nozzle boxes is disposed around said drying cylinder over at least a part of said outer circumference.

31. The drying arrangement according to claim 29, wherein said drying cylinder is heated or is configured to be heated.

32. The drying arrangement according to claim 31, wherein said drying cylinder is a Yankee cylinder.

33. A method for drying a fibrous web or a tissue paper web, the method comprising the step of using the drying hood according to claim 16 to dry the fibrous web or the tissue paper web.

34. A method for drying a fibrous web or a tissue paper web, the method comprising the step of using the drying hood of the drying arrangement according to claim 29 to dry the fibrous web or the tissue paper web.

Description

[0040] The invention is explained in greater detail below with reference to the drawings, in terms of a preferred exemplary embodiment, without restricting the invention's generality. The drawings show the following:

[0041] FIG. 1 a schematic side view of a drying arrangement comprising a drying hood and a drying cylinder,

[0042] FIG. 2 a schematic drawing of a bearing arrangement according to one exemplary embodiment of the invention,

[0043] FIG. 3 a partially cut-away view of an exemplary embodiment of a nozzle box designed according to the invention along the longitudinal axis thereof, and

[0044] FIGS. 4a, 4b structural detail views of the nozzle box shown in FIG. 3 as seen in the direction of the longitudinal axis L.

[0045] FIG. 1 shows a schematized simplified representation of a drying arrangement 1 for use in a machine for manufacturing or treating a material web, in particular a fibrous web in the form of a paper, cardboard or tissue web.

[0046] The drying arrangement 1 is shown as installed in the machine in a side view in with the viewing direction toward the rotation axis AL of a drying cylinder 3. In the illustration, the rotation axis AL runs perpendicularly into the drawing plane.

[0047] Depending on the design of the drying arrangement 1, the drying cylinder 3 may be designed as a heatable cylinder with a closed surface ornot shown hereas a suction-capable cylinder. In the direction of rotation of the drying cylinder 3 (indicated here by the arrow), the fibrous web to be dried is carried along the drying cylinder's outer circumference 6 and fed through the drying arrangement 1. The direction of rotation of the drying cylinder 3 (here clockwise) therefore corresponds to the machine direction, i.e. the longitudinal direction of the fibrous web to be dried.

[0048] The drying arrangement 1 further comprises at least one drying hood 2 which at least partially encloses the drying cylinder 3 in the circumferential direction. To enable straightforward positioning while enclosing a larger area of the drying cylinder 3 in the circumferential direction, the drying hood 2 is designed in two parts. In principle, the drying hood 2 may be a gas-heated creping cylinder hood.

[0049] The drying hood 2 comprises a plurality of nozzle boxes 8. These nozzle boxes comprise a wall and, together with the outer circumference 6 of the drying cylinder 3, define a gap 4 over at least a part 5 of the cylinder's outer circumference 6. Each nozzle box 8 has a multiplicity of outlet openings 9 for discharging air to dry the fibrous web, i.e. discharging the air toward the outer circumference 6 of the drying cylinder 3. The nozzle boxes 8 arranged in the circumferential direction around the axis of rotation AL of the drying cylinder 3 thus run parallel to each other and parallel to the axis of rotation AL with regard to their longitudinal axes. They may be arranged so that their longitudinal axes lie on a circumference around the drying cylinder 3 that has a greater diameter than the drying cylinder 3 itself. The longitudinal axes run parallel to the machine transverse direction, i.e. the width direction of the fibrous web. The length of the nozzle boxes 8 is such that they extend at least over the entire width direction of the fibrous web.

[0050] In this case, adjacent nozzle boxes 8 form intermediate spaces that act as suction openings 7. Via these openings, moist exhaust air may be fed out of the interior of the drying hood 2.

[0051] An air routing system 11, for feeding supply air to the drying hood 2 and removing exhaust air from it, is associated with the drying hood 2. This system may be a part of the drying arrangement 1. The air routing system 11 has at least one supply duct 12 for carrying the (hot and comparatively dry) supply air, and this duct is connected to the individual nozzle boxes 8 in a flow-conducting manner via corresponding distribution ducts, one of which designated as 13 here by way of example. Thus at least one individual distribution channel 13 may be associated with each nozzle box 8. Via the suction openings 7 arranged between or formed by the nozzle ducts 8, moisture-laden exhaust air is discharged from the drying hood 2, or more precisely (in part) from the gap 4 that the suction openings and the outer surface of the drying cylinder 3 delimit. For this purpose, the individual suction openings 7 are connected in a flow-conducting manner to an exhaust duct 15 via individual suction ducts associated with them, one of which is designated as 14 by way of example. The exhaust air (which is more humid than the supply air) is conveyed out of the drying hood 2 via the exhaust duct 15 via the suction openings 7. The suction openings 7 and outlet openings 9 may extend over the entire length of the respective nozzle boxes 8. The drying hood 2 or the drying arrangement are associated with corresponding devices (for example blowers, exhaust systems, heaters), not shown here, for conveying and preparing the air.

[0052] The drying hood 2 forms a housing 16 that houses the components shown. Thus, the housing here partially surrounds the nozzle boxes 8. These nozzle boxes are suspended on the housing 16. When the drying arrangement 1 is operating, the nozzle boxes 8 are subjected to different temperatures due to the supply and exhaust air. This may lead to locally different thermal expansions. Stresses and displacements of the nozzle boxes 8 result, which the housing 16 of the drying hood 2 must absorb.

[0053] For that purpose, according to one embodiment of the invention, the nozzle boxes 8 are specially mounted. FIG. 2 shows, by way of example, another embodiment of a basic bearing arrangement for a single nozzle box 8.

[0054] The nozzle box 8 is mounted on the housing 16 by two bearings 17, 18. The bearings 17, 18 are arranged here in the area of the axial ends of the nozzle box 8viewed from the longitudinal axis L thereof. The first bearing 17 here is designed in such a way that it allows the nozzle box 8 to move relative to the housing 16 along both the longitudinal axis L and a transverse axis Q of the nozzle box 8, the transverse axis being perpendicular to the longitudinal axis. In contrast, the second bearing 18 is arranged in such a way as to allow only a relative movement of the nozzle box 8 relative to the housing 16 along the transverse axis Q (or along a line parallel to that axis). Thus, the two bearings 17, 18 differ by one with regard to their translational degrees of freedom: The first bearing 17 enables two such translational degrees of freedom, while the second bearing 18 allows only one. The representation of the first bearing 17 by quarter circles is intended to indicate that it has the corresponding two translational degrees of freedom. The representation of the second bearing 18 by semicircles is intended to indicate, in contrast, that this bearing only permits one translational degree of freedom. The lines above and below the two bearings 17, 18 indicate stops that limit the corresponding linear movement along the direction shown. Such a limitation may be realized in the exemplary embodiment in relation to the representation of FIGS. 4a and 4b, which will be discussed later, by the contour of the groove 21here, for example, by the end areas of the groove 21: The bolt 19 that engages in the groove 21, in its movement along the transverse direction Q, is prevented by the contour of the groove 21 on both sides from moving laterally outside the contour of the groove 21.

[0055] FIG. 3 shows a schematic and not-to-scale representation of a partially cut-away embodiment of a drying arrangement 1 according to the invention. The diagram shows the two respective axial ends of a nozzle box 8, and the box's suspension on the housing 16 of the drying hood 2. The underlying principle of the arrangement of FIG. 3 corresponds to the bearing arrangement of FIG. 2.

[0056] Both bearings 17, 18 are designed here as a kind of guide rail. An opening 20 is furnished in the housing 16 of the drying hood 2, more precisely in the area of the axial ends of the nozzle box 8. A bolt 19 engages through an opening 20 into a respective groove 21 of the nozzle box 8, namely from outside the housing 16 via the interior of the drying hood 2 enclosed by the housing, into the area of the axial end of the nozzle box 8. The bolts 19 are connected or connectable to the side (outside) of the drying hood 2 that faces away from the nozzle box 8 or to the housing 16, in a nonpositive, positive and/or material fit, preferably by welding. To prevent supply air from escaping at the point where the bolt extends into the nozzle box 8, corresponding seals 22 may be furnished at the respective points on the nozzle box 8.

[0057] The at least one groove 21 of at least one of the two bearings 17, 18 could in principle also be formed by the housing 16 of the drying hood 2 and the bolt 19 of the respective nozzle box 8. The groove 21 or the bolt 19 of at least one bearing 17, 18 could likewise be formed from separate elements for the housing 16 or nozzle box 8.

[0058] A first linear stop 23.1 and second linear stop 23.1 are furnished in the area of the axial end of the nozzle box 8 at which the second bearing 18 is arranged (shown here on the right). Both of these stops serve to prevent linear movement of the second bearing 18 in the longitudinal direction of the nozzle box 8 and also to set a defined gap between the mutually-facing end faces of housing 16 and nozzle box 6 at the respective axial end of the nozzle box 8. The linear stop 23 prevents the movement of the axial end of the nozzle box 8 in either direction in the area where the second bearing 18 is arranged along the longitudinal axis L. In other words, the second axial bearing 18 prevents the relevant axial end from moving in the direction of the longitudinal axis. In the embodiment shown, the two linear stops 23.1, 23.2 are formed by two separate parts. Thus, the second linear stop 23.2 may be an elevation that is arranged in the gap between the facing axial end faces of nozzle box 8 and housing 16, and is preferably fastened to the nozzle box 8 or designed integrally therewith. In addition, the first linear stop 23.1 may serve as a counter stop that is connected to the bolt 19 (or may be designed integrally with the bolt) and is supported on the nozzle box 8 in such a way that the stop prevents the nozzle box from moving in an opposite direction along its longitudinal axis. Both the counter stop and the elevation may also be connected or (detachably) connectable to the bolt 19. They may be designed integrally with the bolt 19 or the element on which they are arranged. The two linear stops 23.1, 23.2 may thus be part of or associated with the second bearing 18.

[0059] FIGS. 4a and 4b respectively show a schematic, partially cut-away representation through the two bearings 17, 18 of FIG. 3, viewed perpendicular to the longitudinal axis. FIG. 4a shows a section along line A-A in FIG. 3, and FIG. 4b shows a section along line B-B in FIG. 3. As may be seen from FIGS. 4a, 4b, the grooves 21 of the two bearings 17, 18 are designed as longitudinal grooves (linear grooves that bound an oval contour). The longitudinal axis or symmetry axis of the grooves 21 coincides with the transverse axis Q of the corresponding nozzle box 8 (or a line parallel thereto). The bolts 19 have an external shape that is complementary to the contour of the grooves 21, so these bolts they may move along the transverse axis Q in the groove 19, into which they engage when the drying arrangement 1 is operating. Here, the bolts 19 are designed as rotationally symmetrical bodies, i.e. as cylinders. Other shapesand also other shapes of the grooves 21would also be possible in principle, as long as they combine to form a guide rail.

[0060] Thus, the mutually-facing end faces of the groove 21 and the outer surface of the bolt 19 form corresponding bearing surfaces of the bearing 17, 18. If both bearings 17, 18 are designed as sliding bearings, the bearing surfaces are the sliding surfaces of the sliding bearing.

[0061] Thus, according to FIG. 4a, the first bearing 17 may be designed in such a way that it has a translational degree of freedom of two, thus allowing the nozzle box 8 to move both in the direction of the longitudinal axis L and the direction of the transverse axis Q.

[0062] As indicated by the dashed lines in FIG. 4b, the outer contour of the first linear stop 23.1, here the counter stop, is designed in such a way that the stop may be inserted axially into the groove 21 in a first position, and through this groove may be inserted above and behind the wall of the nozzle box 8. By turning the bolt 19 around its longitudinal axis, which here coincides, for example, with the longitudinal axis of the nozzle box 8, the bolt is interlocked with the wall of the nozzle box 8. As a result, the bolt is held securely to the wall of the nozzle box 8 and blocks it from moving along its longitudinal axis. Thus, an opposite movement of the nozzle box 8 toward the first bearing 17 along the longitudinal axis L of the respective nozzle box 8 is prevented in both directions. In the interlocked position shown, the bolt 19 may then be connected to the housing 16 in a nonpositive, positive and/or material fit. The counter stop or generally the first linear stop 23.1 may thus be designed as a (detachable) bayonet joint. To summarize, with this bearing 18, only a single translational degree of freedom may be achieved, namely in the direction of the transverse axis.

LIST OF REFERENCE SIGNS

[0063] 1 Drying arrangement [0064] 2 Drying hood [0065] 3 Drying cylinder [0066] 4 Gap [0067] 5 Part of circumference [0068] 6 Outer circumference [0069] 7 Suction openings [0070] 8 Nozzle boxes [0071] 9 Outlet openings [0072] 11 Air routing system [0073] 12 Supply duct [0074] 13 Distribution duct [0075] 14 Suction duct [0076] 15 Exhaust duct [0077] 16 Housing [0078] 17 First bearing [0079] 18 Second bearing [0080] 19 Bolts [0081] 20 Opening [0082] 21 Groove [0083] 22 Seal [0084] 23 Linear stop [0085] 20 Wall region [0086] 21 Support structure [0087] 22 Support unit [0088] 23 Thermal insulation [0089] AL Rotation axis [0090] L Longitudinal axis [0091] Q Transverse axis