Patent Application
20080005921
1. Field of the Invention
The present invention relates to a device for producing and/or finishing a web of fibrous material, in particular a paper or paperboard web, having a heatable and rotatable cylinder, in particular a drying cylinder of a drying section, having a cylinder shell which can be loaded from the inside with a heating fluid.
2. Description of the Related Art
A heated cylinder of this type is known from DE 102 60 509.2. In the known cylinder, tensile stresses which are produced because the inner region of the cylinder expands in a more pronounced manner than the outer region are minimized by the fact that the cylinder shell includes at least two shell layers and the material of the outer shell layer has a greater coefficient of thermal expansion at an assembly temperature which lies below the mean operating temperature and a smaller coefficient of thermal expansion at an assembly temperature which lies above the mean operating temperature than the material of the inner shell layer. A further measure consists in that the layer thickness of the outer shell layer is smaller than that of the inner shell layer.
In drying cylinders of this type, a temperature gradient toward the surface is produced during paper drying. The surface temperature of the cylinder is lower than the temperature of the steam, with which the cylinder is heated; the drying capacity is therefore restricted. Increasing the saturated steam temperature is usually not appropriate for economic reasons.
EP 0 559 628 B1 has disclosed a dryer for drying a web of fibrous material, in which dryer a throughflow cylinder is used in conjunction with a blowing hood. The latter is provided with a nozzle arrangement, with the aid of which drying gas jets are applied to the outer surface of the web which is to be dried, while said web is guided around the heated cylinder over a sector of approximately 270° or more. The circumference of the cylinder is provided with a system of channel lines, into which a coolant can be guided from a coolant source. Water in the web is evaporated outward as a result of the drying gas jets and removed via spaces in the blowing hood. Secondly, water from the web condenses on the cooled circumferential surface of the cylinder and is extracted by suction via the perforation in the outer shell of the cylinder and a vacuum which prevails in the interior of the cylinder. The entire inner space of the cylinder is available for receiving the condensate. As a result, the inner wall of the cylinder has to have a certain minimum wall thickness, in order for it to be possible to withstand the pressure loadings in the case of the cylinder diameters which are used.
What is needed in the art is to increase the drying performance of a heatable cylinder.
The present invention provides at least one channel for passing the heating fluid through which is formed below the outer surface of the cylinder shell.
As a result of the present invention, the heating fluid can be brought very close to the outer surface of the heatable cylinder. As a result, the temperature gradient is lower than in the case of the known devices of the abovementioned type, and the drying performance is increased accordingly.
According to a refinement of the invention, in order to form the at least one channel, a further cylinder shell which is spaced apart from the outer cylinder shell is arranged within the cylinder shell. This can be achieved satisfactorily in structural terms and has the advantage that the entire inner side of the outer cylinder shell can be loaded with heating fluid.
According to a further refinement of the invention, the outer cylinder shell is supported on the inner cylinder shell. As a result, the wall thickness of the outer cylinder shell can be kept small, as the inner cylinder shell acts as a carrying cylinder. As a result, the drying performance can be increased still further.
In order to support the outer cylinder shell on the inner cylinder shell, in particular webs, rods, pins, rivets, bolts, screws and/or other connecting ways can be provided. It is important that the connecting ways are distributed over the surface of both cylinder shells, in order to ensure uniform support.
The webs or other connecting elements can extend axially, in the circumferential direction and/or in a direction which lies between them. In all cases, satisfactory support can be achieved.
In particular in the case of webs which extend in the circumferential direction, it is advantageous if they are provided at least partially with passage openings for the heating fluid. The heating fluid can then flow not only in the circumferential direction but also in the longitudinal direction of the drying cylinder.
The inner shell and the outer shell can be composed of the same or of a different material. In any case, it is advantageous if it is a metallic material, as satisfactory thermal conduction and sufficient stability are then ensured.
As material, in particular, for the outer shell, material having high thermal conductivity can be used. In particular, steel, such as boiler steel, copper, aluminum or bronze, may be suitable. Satisfactory thermal transmission onto the web of fibrous material can therefore be ensured.
The configuration of the inner cylinder as a thick-walled tube is advantageous in structural terms. A satisfactory carrying property is therefore also ensured.
The inner cylinder can also include two or more individual shells. As a result, the thermal expansion behavior and the loadability can be improved.
However, the inner cylinder can also be configured as a framework or as a frame/rib construction. This can also be advantageous in specific applications.
According to a further refinement of the invention, the inner side of the outer cylinder shell is provided with elevations. As a result, the condensate which collects on the inner side of the outer cylinder shell is subjected to turbulence, as a result of which the thermal transfer is improved. The condensate which collects namely has a thermally insulating effect and increases the temperature gradient to the cylinder surface.
According to a refinement of the invention, the inner side of the outer cylinder shell face is configured with ribs and/or lugs and/or a grid or honeycomb structure. Satisfactory swirling of the condensate can therefore be achieved.
The height of the elevations on the inner side of the outer cylinder shell can be selected in such a way that they protrude out of the fluid condensate which is formed during operation. In this way, the elevations have direct contact with the heating fluid, as a result of which the heat can be transferred in an improved manner to the outer surface of the drying cylinder. Moreover, the increase in the surface area as a result of the elevations has a positive effect on the heat transfer. Elevations having a smaller height than the height of the condensate are therefore also advantageous.
The elevations can extend in the cylinder longitudinal direction and/or along a helical line. A special conveying action for condensate discharge can be achieved by a helical line.
According to one refinement of the invention, one or more siphons is/are provided for discharging condensate which is formed during operation. They can be configured such that they are stationary or co-rotate with the drying cylinder. The condensate quantity which collects on the inner side of the outer cylinder shell can be reduced as a result.
The outer surface of the drying cylinder can be provided with a coating or covering. The latter serves, in particular, for corrosion or abrasion protection or for improving the surface, for example in order to avoid adhesion of paper.
According to one special refinement of the invention, web plates which are connected to the inner cylinder shell are provided as connecting elements between the inner and outer cylinder shells. The outer cylinder shell can be formed by covering plates which are likewise connected to the web plates.
In another special refinement of the invention, the web plates and covering plates are combined to form profiles, preferably U-shaped or T-shaped.
According to another special refinement of the invention, the outer shell and the connecting elements are manufactured in one piece, in particular by welding, milling from a tube, casting or by way of other manufacturing processes.
The outer cylinder shell and the inner cylinder shell can advantageously be connected to one another by a press fit. Another possibility includes a screwed connection. Moreover, a conical seat or a form-fitting connection, in particular an L-connection, T-connection or dovetail connection, is advantageous. In order to produce play in the connection, a soldering material can additionally be attached, which melts during subsequent heating of the cylinder and then hardens again. However, the tolerances can also be selected in such a way that there is no play.
Other possibilities for connection include clamping elements, a self-locking or a latching connection. Combinations of all abovementioned connections are also possible, for example a T-groove connection with a conical seat or a T-groove connection with screws.
According to a further refinement of the invention, the inner cylinder shell is formed from individual metal sheets which are connected to the connecting elements and to one another in a suitable manner, for example welding. Both the inner cylinder shell and the outer cylinder shell can also be manufactured in this way.
According to a further special refinement of the invention, bolts are provided as connecting elements between the inner and outer cylinder shells, which bolts are introduced into holes in the outer cylinder shell and are connected to the inner cylinder shell, for example by rotary friction welding or resistance pressure welding or by screwing in. The connection of the bolt and the outer cylinder shell in the holes can take place subsequently, for example by welding. Instead of bolts which are introduced into holes of the outer cylinder shell, bolts can also be provided which are introduced into holes of the inner cylinder shell and are then connected to the outer cylinder shell.
According to a further refinement of the invention, the inner cylinder shell and the outer cylinder shell can be manufactured in each case in one piece over their entire length, for example by casting.
According to another refinement of the invention, only one cylinder shell is provided which is configured as a thick-walled tube and in which channels for the heating fluid are made, for example by deep-hole drilling or milling. In this way, the heating fluid can also be brought close to the outer surface of the drying cylinder and the drying performance can therefore be increased.
In another refinement of the invention, the inner cylinder shell and the connecting elements are manufactured as one piece, to which the outer shell is then fastened by way of a suitable process.
One advantageous connecting type results if the webs between the inner cylinder shell and the outer cylinder shell are divided obliquely over their height. That is to say, one part web is provided in each case on the inner cylinder shell and one part web is provided on the outer cylinder shell. By rotation of the inner and outer cylinder shells with respect to one another, said web parts are brought into connection with one another and a force-transmitting connection is produced.
In order to feed in and discharge the heating fluid, corresponding channels can be provided in the axle of the drying cylinder. The feed channel and the return channel can be nested inside one another here. This saves space and simplifies the construction.
The heating fluid can be distributed onto the hollow space between the inner and outer cylinder shells via radial channels, in particular at least in the cover on the feed side. This is particularly advantageous when, as viewed over the circumference, a large number of individual channels are arranged next to one another, for example in the case of continuous webs in the longitudinal direction of the drying cylinder between the inner and the outer cylinder shells or in the case of a drilled single shell.
Moreover, it can be advantageous to turn the outer shell face. As a result, a smooth surface can be achieved.
The elevations on the inner side of the outer cylinder shell can be milled, drawn, pressed, rolled or cast. Other manufacturing types are also possible.
The webs, metal sheets or other connecting elements between the inner and outer cylinder shells can be manufactured by removing material, by primary forming technology or by forming technology. A combination of these processes is also possible.
An apparatus of the abovementioned type can be used for producing a web of fibrous material, in particular a paper or paperboard web. Here, a drying cylinder of the abovementioned type or a plurality of drying cylinders of this type can be used. A drying cylinder according to the present invention can also be combined with conventional drying cylinders.
During production, contact with the web of fibrous material can be made by the drying cylinders in each case on the same side. However, contact on both sides is also possible. Depending on the application, one or the other variant is advantageous.
All known auxiliary devices can be used for web guidance, for example a suction or blower box, an evacuated or nonevacuated roll, an airblade or a dryer fabric.
In particular, cylinder drying, the boost dryer process, the Condebelt process, a yankee cylinder and a HiDryer may be suitable as conventional drying processes.
Together with the web of fibrous material and optionally a felt, a metal belt can also be guided over the drying cylinder. The latter can be cooled and under stress. As a result, the temperature gradient over the web of fibrous material can be increased and rapid removal of the moisture can therefore be achieved.
The drying performance can be increased by the method according to the invention and the device according to the invention. As a result, a finished dried paper can be achieved with a relatively low dwell time. This can be utilized firstly by the fact that less space is required in comparison with a drying section according to the prior art, which results in savings in the basic price, the building costs for the hall, the machine frames and the fume extraction hood, and also the operating costs for drives and hood ventilation. Secondly, this can be utilized by the fact that a speed increase is achieved with existing space conditions, for example papermaking machine conversions, with an identical length of the drying section. As a result, the papermaking machine can be operated more economically. Moreover, the steam pressure can be reduced with the same drying performance. For example, the differential steam pressure could be utilized for electricity generation, or the energy for steam generation can be minimized.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Referring now to the drawings, and more particularly to
The outer cylinder shell 1 has an outer surface 7, over which a paper web which is to be dried is guided. The outer surface 7 of the outer cylinder shell 1 is of flush configuration with the circumferential faces 8 of the two covers 4. As a result, a continuous contact face for the paper web is provided.
The outer cylinder shell 1 has a thickness d1 which is smaller than the thickness d2 of the inner cylinder shell 2. The inner circumferential face 9 of the outer cylinder shell 1 is at a spacing from the outer circumferential face 10 of the inner cylinder shell 2, with the result that an annular hollow space 11 is formed between the outer cylinder shell 1 and the inner cylinder shell 2. This annular space 11 is connected to radial channels 12, 13 in the two axles 5, 6 of the covers 4 on both end sides of the two cylinder shells 1, 2 via channels (not shown here) in the covers 4. For their part, the radial channels 12 of the axle 5 of the operator-side cover 4 are connected to an axial channel 14 which is provided centrally in the axle 5 of the operator-side cover 4 and opens in a connection end 15. The radial channels 13 of the axle 6 of the drive-side cover 4 are likewise connected to an axial channel 16. Starting from the drive-side cover 4, said channel 16 is guided concentrically with respect to the rotational axis I of the drying cylinder centrally through the two cylinder shells 1, 2 and the axle 5 of the operator-side cover 4, and likewise opens in a connection end 17. Here, the channel 16 penetrates the channel 14 concentrically, with the result that the channel 14 has an annular cross section.
The above-described construction results in a channel system which makes the circulation of heating fluid possible through the hollow space 11 between the outer cylinder shell 1 and the inner cylinder shell 2. For this purpose, for example, heating fluid is fed into the annular channel 14 via the connection end 15. From there, the heating fluid passes via the radial channels 12 into the channels (not shown) in the operator-side cover 4 and, from the latter, into the hollow space 11 between the outer cylinder shell 1 and the inner cylinder shell 2. The heating medium then flows from the operator side through the hollow space 11 to the drive-side and passes there via the channels (not shown) in the drive-side cover 4 into the radial channels 13 of the drive-side axle 6. From there, the heating fluid in turn flows via the central channel 16 back to its connection end 17.
On both end sides, the outer cylinder shell 1 has in each case tapered sections 18, with which the outer cylinder shell 11 rest in each case on a corresponding seat 19 on the circumferential sides of the covers 4. As a result, the outer cylinder shell 1 is supported on the two covers 4. However, the main support of the outer cylinder shell 1 takes place over its length by way of connecting elements 20, as are shown by way of example in
Different variants of the connecting elements 20 between the outer cylinder shell 1 and the inner cylinder shell 2 are shown in FIGS. 3 to 5 and will be described in the following text.
FIGS. 3 to 5 show a circumferential section of a drying cylinder according to the invention having an outer cylinder shell 1 of small thickness d1 and an inner cylinder shell 2 of greater thickness d2 in comparison. There is a hollow space 11 for guiding a heating fluid through between the outer cylinder shell 1 and the inner cylinder shell 2.
At A1 in
At A2, a similar connection is shown between the inner cylinder shell 2 and the outer cylinder shell 1. The only difference is that here, lying opposite the radial projection 24, in each case one tangentially milled seat 26 is provided on the outer circumferential face 10 of the inner cylinder shell 2. As a result, improved support can be achieved.
At A3, a connection is shown which largely corresponds to the connection of A2. The only difference is that the diameter of the screw holes 22 and the screws 23 is smaller here than the corresponding diameters at A2. For example, screws of the size M10 can be used at A2 and screws of the size M8 can be used at A3. The smaller screws save weight in comparison with the larger screws.
A further variant of the connection of A3 is shown at A4. The difference is that the seat 26 here is not milled tangentially but at an angle of 2° with respect to the tangential direction. The milling serves to clamp the outer cylinder shell 1 with respect to the inner cylinder shell 2. For this purpose, after it has been fed onto the inner cylinder shell 2, the outer cylinder shell is rotated in the direction of the rising seat 26, that is to say to the right in
A stronger clamping action is realized in the connection which is shown at A5. Here, the angle of the milling is 5° with respect to the tangential direction. Otherwise, this connection corresponds to the connection of A4.
In the variant which is shown at A6, there is in turn a seat 26 which is milled at 5° with respect to the horizontal direction. However, the radial projection 24 of the outer cylinder shell 1 is not of straight configuration as in the above-described variants, but has an L-shape. The base 27 of the L-shaped projection 24 is supported here on the milled seat 26. As a result, the support becomes more stable.
It is shown at A7 that an L-shaped projection 24 can also be combined with a seat 26 which is milled at 0° or a seat 26 which is milled at 10°.
Finally, it is shown in
In the variant which is shown at B2, likewise T-shaped grooves 33 are provided in the outer surface 10 of the inner cylinder shell 2. However, projections 34 of T-shaped cross section on the shell inner side 9 of the outer cylinder shell 1 engage into them. Assembly takes place here by simply pushing the outer cylinder shell 1 onto the inner cylinder shell 2. The connection can also be configured with or without play here.
Like the groove 31 in the above-described variant, the groove 33 can be milled into the outer surface 10 of the inner cylinder shell 2. However, other production processes are also possible.
The variant which is shown at B3 differs from the variant which is shown at B2 in that the groove 33 for receiving the projection 34 of T-shaped cross section is not milled into the outer surface 10 of the inner cylinder shell 2 but is formed by a corresponding groove profile 35 being welded on. The projection 34 is of correspondingly shorter configuration and is supported on the outer surface 10 of the inner cylinder shell 2 via the groove profile 35. The connection can also be configured here with rearward and lateral play. In comparison with the variant of B1, no groove is therefore required here in the inner cylinder shell 2.
The variant of B4 corresponds largely to the variant of B3. The difference is only in that the groove profiles 35 are not welded to the inner cylinder shell 2 but are screwed via screws 36. For this purpose, the groove profiles 35 have lateral threaded holes 37.
The variant which is shown at B5 is distinguished by the fact that profiles 38 are screwed onto the outer circumferential side 9 of the inner cylinder shell 2, which profiles 38 have, on their radial outer side, a section 39 of T-shaped cross section which can be introduced into the groove 30 of a projection 29 which corresponds in principle to the projection 29 which is shown at B1. For this purpose, screws 36 are screwed into corresponding threaded holes 41 which are provided in lateral flanges 40 of the profile 38. In this variant, there can also be rearward and lateral play between the T-section 39 and the groove 30.
The variant which is shown at B6 is similar to the variant which is shown at B5. Instead of the profile 38, a T-profile 42 is provided here, which is inserted into a groove 43 on the outer side 10 of the inner cylinder shell 2. Moreover, for fastening of the profile 42, only one row of screws 36 are inserted into corresponding threaded holes 44 of the profile 42.
The variant which is shown at B7 corresponds largely to the variant of B4. Here, however, the groove profile 45 is configured with two in each case outwardly pointing flanges 46, in which in each case threaded holes 47 are provided for screwing in the screws 36. Moreover, the groove profile 45 is moved more closely to the inner surface 9 of the outer cylinder shell 1, with the result that the projection 34 of T-shaped cross section is correspondingly shorter.
The variant which is shown at B8 in turn corresponds largely to the variant of B3. Here, however, the groove profile 48 is not welded to the inner cylinder shell 2 but is connected via screws 36 again. For this purpose, the groove profile 48 has corresponding threaded holes 49 on its side which faces the inner cylinder shell 2. Here, as in the variant of B7, the groove profile 48 is also moved closer to the inner surface 9 of the outer cylinder shell 1 and interacts with projections 34 of correspondingly shorter configuration on the inner side 9 of the outer cylinder shell 1.
In the form-fitting variants which are shown in
For assembly, the outer cylinder shell 1 is pushed axially onto the inner cylinder shell 2 in the position of the projection 51 which is shown with dashed lines at C1. The outer cylinder shell 1 is then rotated with respect to the inner cylinder shell 2 in the direction of the angled profile 50, that is to say to the right in
The variant which is shown at C2 corresponds largely to the variant of Cl. Instead of the self-locking profiling of the projection 51, only a screwed connection is provided here for fixing the outer cylinder shell 1 with respect to the inner cylinder shell 2. For this purpose, the inner cylinder shell 2 is provided with holes 54, through which screws 55 are guided which can be screwed into threaded holes 56 which are provided in extensions 57 which are provided at suitable spacings in the axial direction on that side of the projection 51 which faces away from the base 52 of the L-shaped projection 51. The assembly takes place in a corresponding manner to the variant of C1, only the screws 55 also being screwed in after rotation of the two cylinder shells 1, 2 with respect to one another.
In the variant which is shown at C3, the two cylinder shells 1, 2 are also fixed with respect to one another via screws 55. However, in a difference from the variant of C2, these are screwed into threaded holes 58 here which are provided in the angled profile 59 which is connected to the inner cylinder shell 2. Moreover, in this variant, there is no milled seat on the outer side 10 of the inner cylinder shell 2.
There is a milled seat of this type in turn in the variant which is shown at C4. This seat 60 is milled tangentially in this variant. Otherwise, this variant corresponds to the variant of C3. In both variants of C3 and C4, the assembly takes place by rotation of the outer cylinder shell 1 with respect to the inner cylinder shell 2 after the outer cylinder shell 1 has been pushed on and the screws 55 have subsequently been screwed in, in accordance with the variant of C2.
The partial longitudinal section of
In the variant which is shown in
Finally,
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
1 Outer cylinder shell
2 Inner cylinder shell
3 Fastening screw
4 Cover
5 Operator-side axle
6 Drive-side axle
7 Outer side of 1
8 Circumferential face of 4
9 Inner side of 1
10 Outer side of 2
11 Hollow space
12 Radial channel
13 Radial channel
14 Axial channel
15 Connection end of 14
16 Axial channel
17 Connection end of 16
18 Tapered section of 1
19 Seat
20 Connecting element
21 Siphon
22 Hole
23 Screw
24 Projection
25 Threaded hole
26 Seat
27 Base of 24
28 Elevation
29 Projection
30 Groove
31 Groove
32 I-beam
33 Groove
34 Projection
35 Groove profile
36 Screw
37 Threaded hole
38 Profile
39 T-section of 38
40 Flange
41 Threaded hole
42 T-profile
43 Groove
44 Threaded hole
45 Groove profile
46 Flange
47 Threaded hole
48 Groove profile
49 Threaded hole
50 Angled profile
51 Projection
52 Base of 51
53 Seat
54 Hole
55 Screw
56 Threaded hole
57 Extension
58 Threaded hole
59 Angled profile
60 Seat
61 Annular seal
62 Seal
63 Screw
I Rotational axis
II Flow direction
d1 Thickness of 1
d2 Thickness of 2
r Spacing
r2 Spacing
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 000 795.3 | Jan 2005 | DE | national |
This is a continuation of PCT application No. PCT/EP2005/056144, entitled “DEVICE AND METHOD FOR PRODUCING AND/OR TRANSFORMING A WEB OF FIBROUS MATERIAL”, filed Nov. 22, 2005, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP05/56144 | Nov 2005 | US |
| Child | 11773725 | Jul 2007 | US |
