EP0697091B1 - Steam-heated roller - Google Patents

Description

The invention relates to a steam-heated roller in the preamble of the claim 1 described genus.

For the treatment of web-shaped media, e.g. Paper, by pressing, drying and smoothing rollers are used which have large diameters and are heated. In this context, "large" means a diameter of at least 1,000 mm.

These include e.g. in the press section of a paper machine the so-called "Center Rolls", in the dryer section the usual drying cylinders and at Smoothing machines in particular the heated rollers, so-called "gloss calenders" and "Soft calender". The so-called "Yankee cylinders" represent a special case, a combination of drying cylinder and smoothing roller.

Such rollers are preferably heated from the inside by means of fluids Heat transfer medium, preferably with water, steam or thermal oil. The achieved with it Increasing the surface temperature of the rollers either enables their function, by evaporating the moisture in the drying cylinders Paper web causes or promotes its function because the water in the Press at higher temperature and reduced viscosity more easily from the Can squeeze out paper web or because the plasticizability of the paper fibers increased at elevated temperature, making them easier to smooth out.

If steam is used for heating, these are usually rollers cylindrical design. The steam is usually in the interior of the roller cylinder passed where it condenses on the inside. The condensate is over a Siphon led out of the roller.

The disadvantage here is that with such a configuration, the entire interior is under the vapor pressure. This results in restrictions that predominate done for security reasons. They concern the level of the permissible vapor pressure and thus the achievable surface temperature, which in turn is the Process effectiveness limited. Also, depending on the location, you are in limited the application of the roller materials. Because e.g. in the United States so-called chilled cast iron, as it is usually used for a smoothing roller is not standardized, it is out of the question for such applications. Size Rolls for gloss calenders must therefore be made from gray cast iron or nodular cast iron be what in terms of wear behavior of the roller surface is unfavorable.

Because of the mechanical loads, the roller wall cannot be as thin as desired run what a good heat conduction of the heating energy to the heat transfer medium would be desirable.

When certain rotational speeds are reached, it forms depending on Due to centrifugal force, the diameter of the roller on the inside of the roller creates a stable ring Condensate. The steam then no longer condenses on the roller wall, but instead in the condensate ring. On the one hand, this worsens the heat transfer from steam to the roller, but also the temperature profile on the Roller surface.

Some of the disadvantages mentioned, e.g. the bad temperature profile, could be overcome in that with cylindrical rollers for heating with hot water has been passed over. This was done in the central bore of the roller a cylindrical displacement body attached so that a narrow, annular gap remained between the displacer and the inner bore. Through this gap then pushing the hot water through it at speeds above 1 m / s.

The disadvantages of the large, mechanically determined wall thickness and the limitation from the internal pressures remained, however, such rollers build heavy.

The above-mentioned disadvantages could be partially with the so-called peripheral drilled rollers can be overcome. The fluid heat carrier flows - Water or thermal oil - through axially parallel bores just below the roller surface. The way to conduct heat from the heat transfer medium to the roll surface could be reduced significantly.

But this version also has some disadvantages. Water is made Safety considerations only up to a water temperature of max. 170 ° C used. In addition, thermal oil is used. The latter is used in paper mills just accepted as a necessary evil. Smallest leaks on pumps, Sealing heads or the mechanically stressed rollers are considerable Annoyance. The handling of the oil during pumping or other processes is always associated with a risk to the environment.

Even with large rollers, the amount of liquid to be pumped becomes one Problem. When flowing through the roller, the heat transfer medium gives some of it Heat to the roller and loses temperature. Because of Uniformity of the surface temperature is only a limited drop in temperature of the heat transfer medium permitted. It is therefore correspondingly high - depending on the Heating output of the roller - the liquid throughput to choose. The higher this is selected, the lower the temperature drop.

For a heated "center roll" of about 8 m in width is after the release a manufacturer of paper machines with a heating capacity of around 1,800 kW going out. If such a roller is heated with water, the result is one permissible temperature drop in water of 6 ° C a required throughput of 72 ltr / s. At 10 ° C it is still 43 ltr / s.

If such a roller is heated with thermal oil, it increases because of the lower specific heat of this heat transfer medium the throughput to about that Double.

It is now part of the generic German utility model No. G 93 06 176.5 has also been proposed as steam in peripherally drilled rollers Use heat transfer and so some of the disadvantages of water or Avoid thermal oil. However, this implementation poses in the transfer large steam-heated rollers according to the principle proposed some problems.

So it is provided that the heating steam from both ends of the roll in the peripheral drilling is initiated. For this purpose, part of the steam, which flows through the sealing head into the heating-side peg, through the central bore in the roll body to the other roll side and from there into the associated Ends of peripheral holes. Especially because of the pressure vessel regulations this central bore with a diameter that is smaller than 150 mm executed. Then rolls in this regard do not fall under the relevant Regulations in countries where US ASME regulations apply.

With large rollers, however, this would mean that these rollers are almost solid would have to be carried out. The weight savings as they are with an enlarged Central drilling is not possible.

It would be possible to have a pipe for the in an enlarged central bore Install the steam guide, which has an inner diameter that is smaller than 150 mm, but the central support of such a pipe is Consideration of the thermal expansion and the vibrations during operation very much complex.

The distribution of the heating steam is also as in this utility model has been proposed not to be realized in this way with large rolls. With the Diameter increases the number of peripheral bores so that they no longer can be individually connected to the central drilling in the pin. Any collection spaces in the tenons or in the roll body or between both also forbid, because then the prerequisite for not applying of the ASME code (diameter <150 mm) would no longer exist. But also if this doesn't matter, gathering rooms from which the connection should be made the peripheral holes could be done with strong pressure caps against that The inside of the roller must be closed if this is to remain free of pressure itself.

Also for the removal of that to be derived from the peripheral bores of the roller Condensate must be considered again. In the event that a siphon completely fills with condensate, the necessary overpressure is calculated, to blow this siphon out of the centrifugal resistance of one Condensate column from the outer edge of the roller to the center. Will be one Applied overpressure, then blow large amounts at all other siphons Blow-through steam with the corresponding losses. Apart from that comes across the constructive realization of the connection of the individual siphons with the central condensate collector on difficulties.

Finally, the return transport of the condensate accumulation on the drive side is done by a central tube structurally very complex, especially if this itself again in a central steam pipe (see above).

It is the object of the present invention to provide a steam heated roller create that overcomes the disadvantages of the prior art mentioned, especially without leading the steam through the central bore of the roller body gets along as well as no substantial weakening of the components by the Experiences steam channels.

This object is achieved by a steam-heated roller, which according to the characteristic Part of claim 1 is designed.

The features of the subclaims provide expedient embodiments Are defined.

The advantage of such a roller according to the invention is in particular that the central bore of the roller body is kept completely free of heating steam, whereby there is no need for them to comply with the relevant regulations keep less than 150 mm in diameter, any more Take measures to prevent the prescribed flow area gets too big.

Another advantage is that the branching according to the invention the connecting bores now without a substantial weakening of the roller body or the flange pin distributes the steam to all peripheral Bores, especially with larger dimensions with a large number such bores is possible.

According to one embodiment of the proposed roller, it is designed such that that the connecting holes in a driver-side flange of the roller are arranged, which is advantageous in that the short Flow path for the heating steam to its destination only small Heat loss during transport.

For rollers that are in the driver flange flange for some reason, e.g. Lack of space, are not suitable for receiving the connecting channels however, also the possibility to choose a configuration in which the connecting holes are arranged in a drive-side flange pin of the roller, the Feeding the heating steam from the driver side of the roller to the drive side a feed pipe arranged centrally in the interior of the roll takes place.

A roller according to the invention can be designed so that the connecting bores from the central hole in a first flange spigot to everyone branch out to the second peripheral hole, while the neighboring ones lying in between Drilling through passages in a second opposite Flange pins are connected.

In this way, the return of the heating steam to the first flange pin can be guaranteed, the second flange pin only a slight weakening experienced through the passages and the roller body itself free of connecting holes and can thus remain undiminished. The amounts of steam are in this ratio the peripheral bore cross sections so small that an adequate steam supply is possible at low steam speeds.

In a preferred embodiment, a connecting bore is from the Central bore branches to four mouths of the peripheral holes.

In this way it can be achieved that, especially with large rolls, a small one Number of connecting holes starting from the central hole four times the number of peripheral holes supplied. The flange pin is thereby only slightly weakened in its central area, but the steam supply to all peripheral bores to be heated.

There is an advantageous possibility of a steam-heated roller according to the present invention so that a connecting hole from one of the central bore of the flange pin leading to the central bore of the roller first hole from several, from the mouth of the first hole to the Roller body central bore made of second ones made in the flange journal Holes and from again several, the ends of the second holes with there are several mouths of the holes connecting the peripheral bores, wherein the mouth of the first bore at the central bore of the roller body is sealed against this.

In the manner described above, the connection bores are simple to produce feasible by suitable drilling of the flange pin, while by a suitable arrangement of the various sub-holes of the connecting holes Wide branching of the first hole starting from the central hole possible becomes. Since the individual holes within relatively large areas of the axial and radial angles are freely selectable, it can be ensured that despite a Large number of holes in the peripheral flange area no substantial weakening of the flange takes place. Furthermore, the mouth of the first hole which starts from the central bore of the flange and on the inside in the central bore of the roller body opens, there to seal easily because of space required for this inside the roller is not required for further components and is not under pressure or with a damaging seal Medium is filled.

Preferably in the region of the ends of the peripheral bores in the flange pin at least one ring-shaped collecting space for the accumulating in the bores Condensate provided.

This configuration can ensure that the condensate is not collects in undesirable places on its flow path and the steam flow as well as the heat transfer hindered. In addition, several can be used for the condensate peripheral holes in this way central, the roller components only a little debilitating transfers are made available.

Accordingly, the steam-heated roller may have siphons that make up the plenum for draining off the condensate and any blow-by steam with the mouth areas of the peripheral bores at their ends in Connect flange spigot. This is a quick and effective removal of the Condensate ensured, the amount of condensate in the roller is extraordinary remains low.

Around the peripheral holes almost completely free of accumulating The collecting spaces in the first and second flange journals can hold condensate be connected to one another by axially parallel return bores. Hereby can also lead to a central discharge of the condensate and blow-by steam the side of the first flange pin.

In a further advantageous embodiment, the roller according to the invention is thereby characterized in that the collecting space of the flange pin for deriving the Condensate and any blow-by steam through radial channels with one Collection space is connected in the center of the flange, which in turn is connected a double sealing head of the central bore is connected to the outside of the roll.

This radial division of the return transport of the condensate has the advantage that also the pressure difference from the peripheral holes to the central hole is divided. Pressure equalization takes place in the collection rooms. Of the Pressure difference from this point to the peripheral bores means there is a pressure drop opposite, which consists of a centrifugal component and a flow resistance put together. Is the centrifugal force component so large that it alone Corresponds to the pressure difference, a flow can no longer take place. The Pressure difference is adjustable by the proposed design so that the Flow resistance with pure steam flow is greater than the maximum possible Centrifugal resistance, which occurs when the contents of the siphon is pure condensate, so no flow is possible. Stable drainage is so secured.

Preferably, an open connection hole through a flange pin Connect the central bore of the roller to the environment. By this measure it is ensured that there is always ambient pressure in the roller, so that the Roller itself is no longer to be regarded as a pressure vessel and the interior for one large roller can be designed so that relatively thin roller walls are present and thus a lightweight roller is created.

A roller according to the invention can be designed so that for the return of the Condensate from the drive-side flange pin centrally in the inside of the roll arranged return pipe is provided. Although this embodiment is like described in the introduction is very complex, sometimes there is Necessity of such a measure, which is then in an inventive Roller with little effort due to the absence of pressure in the interior of the roller is feasible.

There is also the option of being arranged centrally inside the roll To design supply and return pipes as concentrically arranged pipes, advantageously avoiding unbalance of the entire roller body can be.

Figur 1

einen Längsschnitt durch eine dampfbeheizte Walze mit zwei angeschraubten Flanschen, und

Figur 2

einen teilweise ausgeschnittenen Querschnitt durch einen Sektor des rechten Flansches der in Figur 1 dargestellten Walze.

An embodiment of the steam-heated roller according to the invention is described below with reference to the accompanying figures. Show it:

Figure 1

a longitudinal section through a steam-heated roller with two screwed-on flanges, and

Figure 2

a partially cut cross section through a sector of the right flange of the roller shown in Figure 1.

The roller described in FIGS. 1 and 2 is shown on the left in FIG. 1 Flange 8 driven. In such rollers is between the leader Pin 3 with a double sealing head for steam inlet and condensate drainage and to distinguish the drive-side pin 8.

All connection channels for the steam are according to the invention as bores 4, 5, 6 housed in the driver-side pin 3. To larger distribution spaces too avoid, the holes branch out according to the type of branch Tree. Should e.g. the 48 peripheral bores of a roller with 1850 mm Outside diameter can be supplied with steam, which through the central bore 16 of the pin flows in, six of this central bore 16 initially run radial bores 6 obliquely inwards to the inner flange surface. Of each Exit openings at this point are then two blind holes 5 led out into the journal flange. The flange is by means of cover plates 17th closed at these points. At the ends of the now 12 blind holes of two peripheral holes inclined connecting holes 4 in Spigot flange introduced. This means that every second of the 48 peripheral holes is included Steam supplied.

Instead of the openings closed with the covers 17 on the inside of the An annular channel could also be provided. Then this would be to close with a ring instead of the cover 17.

The connection of the adjacent holes, which are still without Steam supply are carried out in such a way that in the drive-side pin 8 through passages 7 a connection to the steam-carrying neighboring holes will be produced. The amount of steam required in the holes connected in this way first flows as surplus steam through the neighboring hole and then from the drive side. The amount of steam is in the ratio of the peripheral Bore cross sections so small that an adequate steam supply low steam speeds is possible.

The drainage of condensate from the peripheral bores takes place via a small one Siphon tube 9 in the flange in the area of each end of the peripheral Bores 2. This is a quick and effective removal of the condensate ensured. The amount of condensate in the roller remains extraordinary low, especially if you use this construction with one of the usual steam heated structures.

The condensate - possibly together with a small percentage of blow-by steam - is from the steam pressure against the centrifugal force direction radially towards the middle of the roller annular collecting spaces 10 pressed at both roller ends. On the roller circumference these collecting spaces are distributed through a plurality of axially parallel bores 11 connected to each other in the roller body. This passes through these holes 11 Condensate from the drive side back to the driver side of the roller. Enough here then a few radial connecting pipes 12, also in the manner of siphons, to the condensate in a central condensate collector 13 in the middle of the driver's side To guide pin 13 and from there through the double sealing head again Roller out.

In addition, the interior 14 of the roller can be free of steam in the manner described and condensate are kept. A direct open hole 15 from the inside of the roll this ensures through the pin flange to the outside. The roller body can should not be viewed as a pressure vessel.

Claims (14)

1. A steam-heated roll comprising

   a) a roll body (1) having

   a1) a central bore (14) and

   a2) peripheral axially drilled passages (2) for guiding the steam, and having

   b) at least one bolted-on flange pin or trunnion (3) having

   b1) a central bore (16) and

   b2) drilled communicating passages (4, 5, 6) between the central bore (16) of the flange pin (3) and the ports of the peripherally drilled passages (2) of the roll body (1) at the flange pin (3)

   characterized in that

   c) said drilled communicating passages (4, 5, 6) are multiply branched from said central bore (16) of said flange pin (3) in said flange pin (3) to said ports of said peripheral drilled passages (2).
2. The steam-heated roll as set forth in claim 1, characterized in that said drilled communicating passages (4, 5, 6) are disposed in said flange pin (8) of the roll at the guide end.
3. The steam-heated roll as set forth in claim 1, characterized in that said drilled communicating passages (4, 5, 6) are disposed in said flange pin (8) of the roll at the drive end, the supply of the heating steam from the guide end of the roll to the drive end thereof being provided via a supply tube disposed centrally in the interior of the roll.
4. The steam-heated roll as set forth in any of the claims 1 to 3, characterized in that said drilled communicating passages (4, 5, 6) are branched from said central bore (16) in a flange pin (3) to every second peripheral drilled passage (2) whilst the neighbouring drilled passages located in between are connected by passages (7) in the flange pin (8) located at the opposite end.
5. The steam-heated roll as set forth in any of the claims 1 to 4, characterized in that a drilled communicating passage (4, 5, 6) is branched from said central bore (16) to four ports of said peripheral drilled passages (2).
6. The steam-heated roll as set forth in any of the claims 1 to 5, characterized in that a drilled communicating passage (4, 5, 6) comprises a first drilled passage (6) leading from the central bore (16) of a flange pin (3) to the central bore (14) of the roll, a plurality of second drilled passages (5) emanating from the port of said first drilled passage (6) at said roll body central bore (14) and incorporated in said flange pin (3), and in turn a plurality of drilled passages (4) connecting the ends of said second drilled passages (5) to a plurality of ports of said peripheral drilled passages (2), the port of said first drilled passage (6) being sealed off from said roll body (1) at the central bore (14) thereof.
7. The steam-heated roll as set forth in any of the claims 1 to 6, characterized in that in the region of the ends of the peripheral drilled passages (2) in the flange pin at least one ring-shaped receiver space (10) is provided for the condensate occurring in said drilled passages (2) and any stripping or blow-through steam.
8. The steam-heated roll as set forth in claim 7, characterized in that said receiver spaces are provided at both ends of the roll body (1).
9. The steam-heated roll as set forth in claim 7 or 8, characterized in that syphons (9) connect every receiver space (10) for discharging the condensate and any stripping or blow-through steam received therein to the port regions of the peripheral drilled passages (2) at the ends thereof.
10. The steam-heated roll as set forth in any of the claims 8 or 9, characterized in that said receiver space (10) in said second flange pin (8) is connected by axially parallel return drilled passages (11) to said receiver space in the first flange pin (3).
11. The steam-heated roll as set forth in any of the claims 7 to 10, characterized in that said receiver space (10) of said flange pin (3) for discharging the condensate and any stripping or blow-through steam is connected via radial passages (12) to a receiver space (13) in the center of said flange pin (3) which, in turn, is connected via a double sealing head of the central bore to the outside of the roll.
12. The steam-heated roll as set forth in any of the claind 1 to 11, characterized in that an open connecting drilled passage (15) through a flange pin connects said central bore (14) of the roll (1) to the environment so that ambient pressure exists in the central bore (14).
13. The steam-heated roll as set forth in any of the claims 1 to 12, characterized in that for returning the condensate from the drive-end flange pin a realm tube is provided centrally disposed in the interior of the roll.
14. The steam-heated roll as set forth in claims 3 and 13, characterized in that the supply and return tubes centrally disposed in the interior of the roll are configured as a concentric arrangement of tubes.

Images