EP0647286A1

EP0647286A1 - Heated roller

Info

Publication number: EP0647286A1
Application number: EP94914416A
Authority: EP
Inventors: Heinz-Michael Zaoralek
Original assignee: Schwaebische Huettenwerke Automotive GmbH
Current assignee: Schwaebische Huettenwerke Automotive GmbH
Priority date: 1993-04-23
Filing date: 1994-04-25
Publication date: 1995-04-12
Anticipated expiration: 2014-04-25
Also published as: CA2139114A1; DE4313379C2; JP2002339284A; JPH08500862A; FI946067A0; JP3706595B2; FI946067A; WO1994025670A1; US5662572A; DE4313379A1; EP0647286B1

Abstract

The invention concerns a heated roller for material in continuous-web form, in particular paper. The roller has a cylindrical body with at least one flanged neck (12) and fitted with at least one inlet and one outlet line (24) for a heating fluid, in particular steam. Several lines or bores (16) running at least approximately parallel to each other and located preferably at the roller surface carry the heating fluid through the body of the roller. The invention calls for at least one reservoir (28) to be provided inside the roller to hold the condensate formed by condensation of the heating fluid.

Description

Description heating roller

The invention relates to a heating roller for web-like materials, in particular paper, with a cylindrical roller body and at least one, preferably two flange journals, which are each connected to opposite ends of the cylindrical roller body. At least one supply or discharge line for a heating medium runs through at least one of the flange pins. The heating medium, in particular water vapor, is passed through the heating roller through at least one at least approximately axially parallel, preferably peripheral bore or line. The bores or lines are preferably connected to at least one connection space or at least one connection line to the supply and discharge lines. Such heating rolls, as also described in the preamble of claim 1, are often rolls with a more or less solid roll body, in which a larger number of axial bores mostly close to the roll surface, i.e. are introduced peripherally, a heating medium flowing through these peripheral bores or lines and releasing its thermal energy to the walls of the bores or lines and thus to the roller surface.

Another type of roller has a tubular roller body in which the heating medium is passed through the hollow interior of the roller body and thereby releases its thermal energy to the interior of the roller body.

A significant difference between these two known types of heating rollers is that the generic heating roller type can be used for liquid heating media, such as some water and thermal oil, but has so far not been considered for a particularly advantageous heat transfer medium, namely water vapor. This is due to the fact that the water vapor condenses at least partially within the bores or lines, whereby it emits its heat for the most part or as a whole to the roll body, the roll surface and thus to the web-like material to be processed. The resulting condensate is pressed outwards by the centrifugal forces that usually occur in paper processing machines, such as release supercalenders, etc., so that the condensate cannot flow away. As a result, the holes are increasingly filled with condensate during operation until the entire holes are finally closed by water. This means that the throughput of water vapor and, in parallel, the heating output of the heating roller is practically zero. In this case, the known heating roller of the generic type would have to be braked to such an extent that the centrifugal or centrifugal forces are no longer sufficient to retain the water in the bores or lines. In an extreme case, a known roller of the generic type would even have to be brought to a standstill in order to allow the condensate to run off at least from the bores lying at the top. It is clear that, both during the clogging process and during the subsequent braking and emptying processes, situations occur in any case which lead to a heating roller of the generic type being heated unevenly, so that irregular temperature profiles occur along the heating roller that lead to thermally induced deformations and tension etc.

For such reasons, water vapor as a heating medium has so far not been considered for the generic roller type. Conversely, water vapor is an ideal heating medium, since it always condenses inside the roller and releases its heating power at the coldest points. This property of the heating medium itself ensures that there is always an approximate or precisely coordinated uniform temperature profile over the surface essential for the processing of the web-like material or over the entire surface of the heating roller.

In contrast, the use of steam in heating rollers of the other type presents no problems, since the remaining condensate can be removed from the roller in a known manner either by means of a standing siphon or a commercially available siphon rotating with the roller.

However, the generic roller has a significant cost advantage over the roller of the other type, namely in that the heating rollers of the other type have a very large cavity located in the roller body, and therefore in many countries, e.g. the USA, subject to particularly complex acceptance conditions, since they are considered to be pressure vessels. It should be borne in mind that the water vapor pressure is approximately 20 bar at a temperature of approximately 211 ° C. and approximately 40 bar at a temperature of approximately 249 ° C. However, these complex acceptance conditions do not apply to containers that have an inside diameter of less than 6 inches, namely less than approx. 152.4 mm, with each of the individual axial bores or lines of the generic roller type being defined when defining the container a single container is viewed.

This consequently has the advantage that a roller of the generic type can be manufactured and offered far more cost-effectively than a roller of the other type while maintaining the same quality, functionality and operational safety.

The following must also be taken into account: To meet the line pressures, the For example, for release supercalenders must be relatively high, namely up to approx. 450 or even 500 kN / M and, in individual cases, moreover, steel must be used as the material for the heating rollers, especially since the roller wall is as possible for heat transfer to the paper must be kept thin. The roller wall made of steel can also be surface hardened. However, in connection with the special acceptance conditions, this increases the manufacturing costs for heating rollers of the other type.

It is the object of the present invention to develop a roller of the generic type in such a way that it can at least substantially overcome the disadvantages of the heating roller according to the prior art; in particular, the generic roller is to be developed in such a way that it can be operated at least partially with gaseous heating media, in particular water vapor.

This object is achieved by a heating roller with the features listed in claim 1.

Advantageous refinements of the heating roller according to the invention can be seen from the subclaims and the other registration documents.

The advantages which can be achieved with the present invention are based on the fact that at least one collecting space for receiving the condensate of the heating medium, preferably water vapor, is arranged in the heating roller.

This makes it possible to use the generic type of roller also for water vapor, since centrifugal forces or centrifugal forces now press the condensate into the correspondingly arranged collecting space, from where the Condensate, preferably water, can be derived.

This means that heating rollers for super calenders or release super calenders, which are preferably operated with steam, can also be designed in accordance with the generic type of roller, as a result of which the costly acceptance conditions and the associated demands on the rollers become obsolete.

In addition, water vapor is available in every conventional paper mill, so that in the case of direct steam heating, an additional heating station with a heat exchanger for converting steam energy into hot water and a separate circulation pump for the heating medium can be dispensed with.

In addition, the essential advantage of the generic roller, namely that the bores or lines lie very close to the roller surface, so that the heat transfer is very cheap, can be combined with the favorable acceptance conditions, since the bores have a smaller inner diameter than 6 inches or 152.4 mm, so that the water vapor-carrying holes or lines are no longer regarded as pressure vessels, the expensive steel mostly used in connection with the difficult acceptance conditions can be dispensed with, and cheaper cast iron can be used.

In addition, the roller according to the invention provides a much higher surface temperature than a displacement roller, that is to say a roller of the type, at a predetermined steam temperature.

In addition, water vapor is almost always present up to pressures of approximately 10 bar, ie approximately 180 ° C., and is therefore unproblematic. The amount of condensate present in the roller according to the invention is also extremely small, so that the risk potential of the roller according to the invention is low, even compared to a correspondingly heated displacement roller.

In addition, there is no drop in temperature of the heating medium, in particular water vapor, as it passes through the roller body, so that a completely balanced temperature profile is present, at least over the area accessible to the web-like material, preferably over the entire roller area.

The controllability of the heating power of the heating roller according to the invention is extremely variable and adjustable from zero to a maximum heating power, which will be discussed in more detail below.

The sealing heads for the flange connections required for the heating roller according to the invention can be made much smaller since, among other things, the amount of condensate at a heating power of 100 kW is only about 3 1 per minute. In addition, it is not necessary to place additional strain on the sealing heads due to the dynamic pressure of a pump which is arranged within a circuit for a heating medium. Ultimately, no additional energy expenditure for heating the movement of the heating medium is required. Very high temperatures, which are associated with correspondingly high pressures, can be achieved with the heating roller according to the invention. Since sealing heads are available that can hold up to 17 bar, temperatures around 207 ° C can be put into practice without any problems.

The collecting space can advantageously have a circumferential annular space on at least one of the axial end regions of the roller body and / or in the region at least have one of the flange pins. This annular space should be arranged opposite the bores or lines in such a way that the centrifugal forces or centrifugal forces cause the condensate that accumulates within the bores to be pressed into the surrounding annular space or spaces, from where the condensate, in particular Water that can be easily removed.

Each bore can advantageously be assigned an annular space which has a corresponding arrangement in order to absorb the condensate via the effect of the centrifugal force.

Advantageously, each of the collecting spaces, however designed, is connected to a discharge opening for the condensate via an outlet, for example in the form of at least one bore or at least one tube. This discharge opening for the condensate can be identical to the supply or discharge for the heating medium, in particular water vapor, but should in any case be provided in the end regions of the heating roller and in particular through one or both flange pins of the heating roller.

In order to achieve an additionally increased uniformity of the temperature professional over the roller body, an axially parallel, generally central bore can preferably be passed through the roller body, through which the heating medium, in particular water vapor, is directed to the other end of the heating roller or the roller body is, so that uniform amounts of steam with uniform temperature can act from both sides of the roller body.

The temperature of the heating roller according to the invention is advantageously regulated via the outflow quantity of the condensate. Such regulation can be make a valve device that could be arranged outside the heating roller according to the invention itself.

In the previously heated steam rollers of the type other than the generic type, it was not possible to regulate the temperature of the roller by throttling the amount of steam without obtaining an extremely uneven temperature profile. A throttling leads to a pressure drop in the roller because the reduced amount of steam that is fed into the roller immediately condenses at the first colder point, so that the distant areas are no longer adequately supplied with thermal energy. These more distant areas consequently remain cold, and a completely non-uniform temperature profile arises, which at the same time is associated with large deviations in the roller diameter, which may well be in the range of the thickness of the web-like material to be processed and beyond.

Even with the roller according to the invention, it is not possible to simply restrict the steam supply, but the above-mentioned regulation of the condensate drainage via a valve located outside the roller enables the roller temperature to be continuously increased over the entire temperature range up to the maximum operating temperature of the heating roller according to the invention regulate.

The bores or lines, which are arranged near the roller surface, increasingly fill with condensate or water, which is not or only partially drained off. In this way, the amount of water held in the holes increases and the free surface area of the holes that can absorb the heat from the condensing steam decreases. In this way, the roller can with an increasing amount of condensate in the bores or lines absorb a smaller amount of heat so that the heating power of the roller according to the invention is possible by regulating the amount of condensate flowing off. In order to create a gradient for the condensate, the bores or the lines can also be inclined slightly outwards from the center. The bores or lines can either deviate from the axial parallel towards the center of the roll by approximately 1 to 10 mm or can also run exactly axially parallel.

Advantageously, at least one of the collecting spaces has at least one end of the holes or lines or a respective hole or line with a rounded pocket with a diameter that is preferably smaller than the diameter of the peripheral hole, the pocket being opposite the peripheral hole or the line can be offset to the outside. This can prevent the condensate located in the bores or lines near the roller surface in the event of the loss of centrifugal forces acting on the condensate in a surge from the bores or lines in the upper region of the roller through the steam-supplying connecting lines or connecting bores flows into the bores or lines of the lower region of the roller according to the invention. If the roller according to the invention is stopped when changing a paper roll, the condensate cannot accumulate excessively in the lower region of the stationary roller, in order in this way to produce an uneven temperature profile over the diameter of the roller or over the circumference of the roller to lead so that relevant tension and bending of the roller body can be prevented even at a standstill. The steam supply lines must of course be attached in such a way that they open into the collecting space in such a way that there is an obstacle to the otherwise draining condensate. On the other hand, the at least substantially axially parallel peripheral bores or lines should pass into the collecting or annular spaces or pockets in such a way that no operating obstacles arise for the condensate flowing from the bores into the annular space or the pocket. Furthermore, the connection to the drain, for example in the form of at least one hole or at least one tube, should be provided in such a way that no condensate congestion can form here either. Thus there should be essentially no restriction for the condensate flow within the drain lines through which the condensate must pass.

Conversely, however, it should be possible, if necessary, to remove the entire amount of condensate from the roller according to the invention during the slow running of the roller according to the invention or while it is stationary.

Insofar as larger amounts of condensate are produced during the operation of the roller according to the invention, it may be advantageous to use a retention device, preferably within the bores or lines or within the connection spaces or the connection lines at the end areas of a respective hole or line Check valve, non-return flaps or the like. To provide the condensate at least substantially in the event of slow running or the standstill of the roller according to the invention, in order to collect condensate in the lower region of the roller according to the invention, which leads to an uneven temperature profile and thus to tension and bending of the roller can prevent.

To thermally collect the amounts of condensate that may accumulate in the collecting space or spaces from the roller or the bores or Lines and thus uncoupled from the roller body, the end regions of the bores adjoining the respective collecting spaces should be surrounded by a heat-insulating material.

The roller designed according to the invention can be used not only for the release supercalenders already mentioned above, but also in so-called gloss or soft calenders, in which one or more plastic-coated rollers press the paper web against a heated roller, the surface temperatures usually not higher than must be around 160 to 170 ° C.

As already indicated above, the outstanding advantage of the roller according to the invention lies in the fact that in each of the bores and at every point of the bores or the roller body there is an almost identical vapor pressure and thus almost the same temperature. Even the slightest temperature deviations along a bore or along the roller body mean that more steam condenses at this point, releases a large part of its energy during the condensation, and thus the temperature at this point is adjusted again. Far less steam condenses at adjacent points, so that an area that is too cold is automatically heated up.

For the heating of the heating roller according to the invention, for which preferably steam is possible, there is also the advantageous possibility of regulating the temperature of the incoming steam by moistening the steam pressure. In this way, the steam that can be introduced into the heating roller according to the invention can be saturated or even saturated with moisture, so that in the latter case the heating steam is present as saturated steam. For all other rolls and heating media, when the flow passes through the roll body as a result of the heat given off by the heating medium and the cooling of the heating medium that occurs along its path through the roll body, there are temperature differences which make the treatment of the web material more uniform and in addition to the different temperature Shape inaccuracy of the roll lead, which also adversely affects the web material.

A preferred embodiment of the roller according to the invention is explained in more detail below with reference to the attached figures. Further advantages and features according to the present invention are disclosed. Show it:

FIG. 1 shows a detail from an axial longitudinal section through a roller according to the invention in an end region of the heating roller according to the invention;

FIG. 2 shows a partial cross-sectional representation in a region of the heating roller designed according to the invention in one of its end regions; and

Figure 3 is a flow diagram for the steam supply or condensate removal with respect to the heating roller according to the invention.

In Figure 1, the heating roller designed according to the invention is generally identified by reference number 10. The roller has a flange pin 12, preferably on each side, and a cylindrical roller body or roller jacket 14, the surface 11 of which is used for the pressure processing of a web-like material, in particular paper, plastic or the like. A heating medium is introduced into the heating roller 10 according to the invention via a feed line running through the flange 12. In the embodiment shown in FIG. 1, the incoming water vapor is introduced into connecting lines 24, and part of the water vapor introduced via the supply line 36 is led to the other end of the heating roller 10 via an axially parallel line 20 arranged in the central region of the roller 10 according to the invention. The water vapor passes via the connecting line 24 to the collecting space 28, in which water vapor condensate can accumulate during the operation of the heating roller 10 according to the invention, that is to say when sufficient centrifugal forces occur.

The collecting space 28 connects to the at least approximately, preferably substantially exactly axially parallel bores or lines 16. In each case one collecting space 28 can be assigned to one bore or line 16. On the other hand or in addition, a circumferential collecting space could also be assigned to all the bores 16.

In the present case, the collecting space 28 is provided in the flange 12 connected to the roller body 14 via fastening means 32. However, it could equally well be arranged in the end region of the roller body 14.

The plenum 28 is axially offset from the central axis of the associated bore 16. This is to prevent the condensate from running off through the connecting line 24 into the lower region of the heating roller 10 according to the invention during slow running or standstill of the roller, as a result of which uneven temperature profiles, diameter deviations and an adverse influence on the web-like material to be processed can occur. The design of the collecting space 28 with a smaller diameter and the axial displacement creates an obstacle 38 which prevents the condensate from flowing off the feed 24 prevented.

Part of the steam is guided to one of the corresponding line arrangements shown in FIG. 1 or in FIG. 2 on the opposite side of the heating roller 10 and from there in the opposite direction into the drilling portions by the boring 20 arranged centrally and axially parallel within the heating roller 10 according to the invention or lines 16 and thus introduced into the roller body 14 in order to achieve an even temperature profile in this way.

Insulations 30 are arranged in the edge region or in the end region of the bores 16 in order to bring about a thermal decoupling of the condensate, which can be contained within the collecting space 28. Here, further insulation can be provided in the border area between the flange pin 12 and the roller body 14, e.g. on the side of the flow obstacle 38 pointing toward the roller body 14.

In order to ensure the drainage of the condensate during operation, a boring or a tube 26 is provided which is connected to the collecting space 28. The condensate is conveyed from the collecting space 28 into a condensate collecting space 22 and from there into a condensate drain line 18 via this tube 26. The condensate can be conveyed via the steam pressure or via a negative pressure applied to the space 22 and thus to the line 18. In order to arrange the tube 26 in the flange 12, a radial channel can be drilled into the flange 12, the tube 26 can be inserted into this resulting radial channel, closed to the outside by means of a closure 34 and fixed within the channel. The tube 26 has an opening 27 which extends as far as possible to the radially outer end of the collecting space 28 in order not to form an obstacle for the condensate.

In the end area of the bore 16 or in the area of the collecting space 28, retention devices, such as a check valve or the like may be provided in order to prevent the condensate from flowing off and the condensate from accumulating in the lower region of the roller 10 according to the invention when the roller according to the invention is at a standstill or running slowly. In this case, the flow obstacle 38 according to FIG. 1 is not absolutely necessary, so that the connecting line 24 can also open directly into the bore 16 without having a direct connection to the collecting space 28.

Instead of the direct supply of the steam to each peripheral Bohmng 16 and the individual discharge of the condensate from each Bohmng 18 via tubes 26, annular spaces can also be provided at the roller ends, which are connected to all peripheral Bohmngen 16 and via which the distribution of the steam and from which the condensate is removed in the manner according to the invention.

Outside the roller 10 according to the invention, a valve device can be provided following the line 18, via which the condensate outflow and thus the temperature of the roller can be controlled, the condensate being driven via the flow path shown above, driven by the centrifugal force and / or the vapor pressure and / or a suction created from outside can be withdrawn.

The condensate collection spaces 22 can also be located in the flange spigot 12, through which the condensate can reach the central axially located line 18.

If the central axial line 18 is to be dispensed with, it is advantageous if the water vapor can be conducted via supply and discharge lines 36 provided in both flange journals 12.

FIG. 2 shows a partial cross section through a heating roller designed according to the invention, from which in particular the position of the collecting space 28 for the condensate, which is offset to the drilling or line 16, can be seen.

Otherwise, the parts shown in Figure 2 have the same reference numerals as the parts shown in Figure 1.

In the connecting line 24, which is arranged obliquely with respect to the horizontally oriented connecting line 24, the necessary parts, such as the collecting space 28 and the parts connected to the pipe 26, are not shown, in addition to the parts required in connection with the vertically oriented connecting line 24 stand to emphasize again separately.

FIG. 3 shows a possible circuit for a roller 10 according to the invention. The supply of heating medium or steam to the heating roller 10 according to the invention can be controlled via a supply line 40 and a steam shut-off valve 42 which controls the supply line. In this case, the water vapor which is preferably introduced into the heating roller 10 according to the invention is, if appropriate, partially moistened or completely saturated after a pressure release, so that the water vapor supplied to the heating roller 10 is saturated steam or saturated steam. The embodiment shown indicates that the water vapor through one Flange pin supplied to the roller 10 according to the invention and the condensate with or without steam content is removed from the opposite flange of the heating roller 10 according to the invention. Of course, both measures could also be carried out over the same flange of the heating roller 10 according to the invention. A discharge line 44 for the condensate is optionally provided with steam admixture on the outflow side. The circuit has a condensate separator 46, which works in one of the known ways. A bypass valve 48 is arranged parallel to the condensate separator and can be provided, for example, for safety purposes. In addition, the circuit for a heating medium for the heating roller 10 according to the invention has a condensate control valve 50, by means of which the amount of condensate which is removed from the heating roller 10 can be controlled. This results in a continuous regulation of the temperature of the heating roller 10, namely by making the discharge for the condensate in the bores 16 or lines 16 near the roller surface in the heating roller 10 according to the invention more or less high. If a lot of condensate is removed, that is, the condensate control valve 50 is completely open, the steam introduced into the heating roller 10 can completely release its thermal energy to the surface of the bores 16. If, on the other hand, the condensate is only partially discharged, a large part of the surface of the Bohmngen 16 is occupied by condensate and is not accessible to the water vapor, so that the water vapor can only release its thermal energy to parts of the surface of the Bohmngen 16. If the condensate control valve 50 is completely closed, then no more condensate runs off, the bores 16 become clogged with condensate and the steam flow is prevented. In this case, the heating roller 10 immediately cools down together with the condensate contained therein.

Claims

1. heating roller (10) for web-like materials, in particular paper, with a cylindrical roller body (14), with at least one flange pin (12), with at least one inlet or outlet (36) for a heating medium, in particular water vapor, with several, at least approximately axially parallel, preferably peripheral bores or lines (16) in order to conduct the heating medium through the roller body (14), characterized in that at the ends of the peripheral bores or lines (16) at least one collecting space (28) within the heating roller (10) is designed to receive the condensate which arises from the condensation of the heating medium, preferably water vapor.

2. Heating roller according to Anspmch 1, characterized in that at least one connection space or at least one connection line (24) for the Bohmngen or lines (16) is provided.

3. Heating roller according to one of claims 1 or 2, characterized in that each collecting space (28) has a circumferential annular space on at least one of the axial end regions of the roller body (14) and / or in the region of at least one of the flange pins (12).

4. Heating roller according to one of claims 1 to 3, characterized in that each Bohmng or line (16) is assigned a collecting space (28).

5. Heating roller according to one of claims 1 to 4, characterized in that a drain, for example in the form of at least one Bohmng or at least one tube (26), is provided corresponding to a respective collecting or annular space (28).

6. Heating roller according to one of claims 1 to 5, characterized in that in particular within the roller body (14) a line (20) is provided to the heating medium, in particular water vapor, to another end of the heating roller (10) or the roller body (14).

7. Heating roller according to one of claims 1 to 6, characterized in that the discharge amount of the condensate is preferably adjustable via a valve device.

8. Heating roller according to one of claims 1 to 7, characterized in that at least one of the Bohmngen or lines (16) is inclined either to the center of the roll and to the roll axis, in particular deviates by approximately 1 to 10 mm from the axial parallelism, or exactly axially parallel.

9. heating roller according to one of claims 1 to 8, characterized in that at least one of the collecting spaces (28) at least at one end of the Bohmngen or lines (16) has a rounded pocket (28) with a diameter which is preferably smaller than the diameter of the peripheral Bohmng or line (16), wherein the pocket (18) relative to this Bohmng or line (16) is offset to the outside.

10. Heating roller according to one of claims 1 to 9, characterized in that the Temperature control by a pressure control of the steam, preferably with subsequent humidification of the steam, can be carried out.

11. Heating roller according to one of claims 1 to 9, characterized in that at least six at least approximately axially parallel peripheral Bohmngengen or lines (16) are arranged.

12. Heating roller according to one of claims 1 to 10, characterized in that in the or the connection spaces or connecting lines (24) at the end regions of a respective line or Bohmng (16), a retaining device, preferably a check valve, check valves or the like. , is arranged to retain the condensate.

13. Heating roller according to one of claims 1 to 12, characterized in that the end regions of the lines or Bohmngen (16) are provided with a heat insulating material (30).

14. Heating roller according to one of claims 1 to 13, characterized in that at least one constriction (38) is provided in the end regions of at least approximately axially parallel Bohmngen or lines (16), in particular to retain condensate when the roller is at a standstill.