AT13495U1 - Heat transfer roller - Google Patents

Abstract

A roll or cylinder comprising a shell (1) consisting of an inner shell part (2) and an outer shell part (3), which latter is tautly joined to the inner shell part to form a flow space for the heat transfer medium, and to end portions of the shell having fixed end portions for forming a heat transfer medium supply channel and discharge channel on the roller, the inner shell portion (2) having flow channels (4, 5) for the heat transfer medium, the roller or cylinder having longitudinal distribution channels (12) Vertical distribution channels (13) and / or distribution grooves (14) for providing a directional flow connection for the heat transfer medium to one or more heat transfer medium flow channels (4, 5).

Description

Austrian Patent Office AT13 495U1 2014-01-15

description

HEAT TRANSFER ROLLER TECHNICAL FIELD

The present invention relates to a heat transfer roller, such as a Thermowal ze or a cylinder that can be used in a fiber web machine for the treatment of a fibrous web, such as for drying, pressing or smoothing paper or cardboard. In the roll according to the invention, the roll shell consists of an inner and an outer shell part, wherein the outer shell part is fastened tightly on the inner shell part, for example by shrink connection technology or welding or in another corresponding manner. The invention particularly, but not exclusively, relates to the arrangement of flow channels for the heat transfer medium with the aim of providing a roll of high heat transfer efficiency and uniform heating effect.

STATE OF THE ART

In paper, board and pulp machines web-like material can be heated, dried, calendered, wet-pressed and / or cooled by means of heat transfer rollers such as thermo rolls or drying cylinders. For example, the heat output required in the drying of paper and cardboard is generated with heatable rollers, which include u. a. the traditional drying cylinders to be heated with condensing steam belong. The jacket of the drying cylinder is mainly loaded by the screen and web tension. Especially in calanders, the heat output required by the railway is generated by more powerful thermo rolls, in which high temperatures (almost 300 ° C) heat transfer oil is used as the heat transfer medium. Exposing nip forces act on the jacket of the thermo roll, which is why the design of its jacket construction is significantly stronger than with the drying cylinder. With the conventional peripherally drilled hot oil heated thermo rolls, based on the surface area of the roll shell outside, typically a specific heat transfer performance of 15-40 kW / m2 can be achieved. The induction-heated rollers of the Tokuden type can achieve a specific power of 50 kW / m2. For today's newest high-performance thin-walled thermo rolls, the maximum heat output is 65 kW / m2.

In order to achieve the required heating and drying performance, the surface temperature of the thermo rolls under demanding process conditions must be raised to 200-250 ^ or even higher. The thermal power to be transferred by the roller is known to depend on the heat transfer contact between the web to be heated and the roller and the type of material to be heated, such as the length of the contact, the basis weight and the moisture of the web. High production speed combined with long-lasting contact, wet web and high thermo roll surface temperature mean that the heat output to be transferred from the thermo roll has to be very high. For certain new drying processes, a heat transfer capacity of 300-850 kW / m is desired.

It is known that the heat of the thermo roll by supplying serving as a heat transfer medium fluid or heat transfer medium gas in the existing inside the thermowell flow channels and especially in the existing holes in the jacket, from where the heat in the jacket and on to the roll surface wanders, generates.

Known, present in the interior of the thermo roll peripheral bores substantially from one to the other end of the roll shell reaching channels. When flowing through a peripheral bore, the heat transfer medium cools, which is why in the end of the channel has a lower temperature. As a result, the heat distribution in the roll shell is not completely uniform. In addition, due to thermal expansion differences on the roller, small dimensional changes occur, which in turn can lead to vibration problems on the rotating roller. These known problems have been attempted by arranging flow-accelerating displacement bodies in the duct systems and by opposing flow directions in adjacent ducts, for example in accordance with the duopass or tripass principle.

As is known, the production of peripheral bores on thermo rolls is a demanding task, and the production of peripheral holes close to the outside of the roll can not be accomplished with good dimensional accuracy. Drilling is possible in practice only in the axial direction of the roller. The inaccuracy and limitations in the arrangement of the channel system lead to an uneven heat distribution and increase the vibration problems.

In the utility model FIU 7470 a heat transfer roller is described in the outer jacket between the inner and the outer shell part heat transfer medium flows. The outer shell part is made thin such that the heat transfer capacity is 50-250 kW / m or even up to 500 kW / m web width.

The object of the present invention is to reduce the disadvantages associated with the prior art and weaknesses and to provide a solution for heating and / or cooling in situations where a high heat transfer capacity and a uniform heating effect are needed.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a roller or a cylinder which comprises a sheath consisting of an inner sheath portion and an outer sheath portion, the latter joined tightly against the inner sheath portion to form a flow space for the heat transfer medium and at the ends of the shell having fixed end portions for forming a heat transfer medium supply channel and -Abführkanals on the roller, the inner shell portion having flow channels for the heat transfer medium and the roller or the cylinder means for forming a directional flow connection for the heat transfer medium to having one or more heat transfer medium flow channels.

The outer shell part may be fixed to the inner shell part, for example by welding or by thermal shrinking.

Preferably, longitudinal flow channels for the heat transfer medium are formed on the outside of the inner shell part. These flow channels preferably run approximately parallel to one another, but not necessarily in the direction of the roll axis. To reduce the tendency of the roller to oscillate, these flow channels can, for example, run helically.

Preferably arcuate flow channels are formed on the outside of the inner shell part to form a flow connection for the heat transfer medium between two or more longitudinal flow channels.

Preferably, the inner shell part has vertical channels for forming a flow connection for the heat transfer medium between the inside and the outside of the inner shell part.

The said vertical channels may, but need not necessarily be deviating from the radial direction of the shell.

Preferably, a flow distributor is disposed within the inner shell portion of the roller or the cylinder having means for forming a directional flow connection for the heat transfer medium to one or more vertical channels.

Preferably, the outer shell part of the roller or of the cylinder to ensure an effective heat transfer is made so thin that the heat transfer resistance from the heat transfer medium to the fibrous web is as small as possible to AT13 495U1 2014-01-15. Preferably, the outer shell part is made of steel of a thickness of 5-30 mm.

The heat transfer capacity of the roller under demanding process conditions is preferably 300-850 kW / m. The outer diameter of the roll may be in adaptation to the process and the plant preferably 800-1850 mm, but even up to 6500 mm.

The roller preferably has a heat transfer region on the casing part, with which heat is to be transferred from the casing part to the fibrous web to be treated or heat is to be transferred from the fibrous web via the casing part. Preferably, the longitudinal flow channels are arranged in the heat transfer area, and the heat transfer area has in web transverse direction the same width as the web area or is slightly narrower than this.

The specific heat transfer capacity of the roller is preferably 65-150 kW / m 2 in terms of the outer surface unit of the heat transfer area.

In one embodiment, the vertical channels formed on the inner roll shell part are preferably arranged laterally from or at the edges of the heat transfer region of the shell part, that is to say essentially the region of the web. The position of the vertical channels can be selected according to the web width in the desired manner and unnecessary heating of the end portions of the roller can be avoided.

In another preferred embodiment, at least part of the vertical channels present on the inner roll shell (part) are within the heat transfer area of the shell part, i. So arranged the railway area. With this solution, heat transfer medium can be supplied to the longitudinal channel system at several points or heat transfer medium can be removed from the longitudinal channel system at several points, or the longitudinal channels can be shorter, thereby shortening the fluidic length of the heat transfer medium circuit in the narrow longitudinal channel. In this way one achieves a lower pressure loss, a more uniform heat distribution in the jacket and a higher heat output.

The flow channels of the roller may also consist of on the inner shell part ausgebil-Deten peripheral holes according to the prior art.

According to some embodiments, flow channels are arranged at different points of the roll in the desired density. Flow channels may be disposed at the interface between the outer and inner shell portions at different distances from the adjacent flow channels.

The flow channels of the roller for the heat transfer medium can be arranged in the determined by the requirements of manufacturing technology and operation permissible minimum distance from the roll surface, whereby the condition caused by the roll shell heat transfer resistance can be reduced. The flow channels can be arranged below the roll surface at desired mutual distances, even several times closer to each other than in the prior art. In conjunction with the roll surface flow channels can be formed whose flow cross section and their mutual distance is smaller than in peripheral bores. The flow channel system makes it easy to realize various known circulation options, such as duo-pass, tripass, multipass and completely new circulation systems.

The fact that it is now possible to decide more freely about the size and the arrangement of the flow channels close to the roll surface, it is easier to achieve a uniform heat transfer effect with the roller.

Thanks to the uniform heat transfer, the roll surface can be consistently heated to the desired temperature, whereby the process caused by cooler surface areas process defects are avoided. In addition, this solution can reduce the dimensional errors caused by uneven heat distribution as well as the tendency to oscillate.

According to one aspect of the invention, the longitudinal, circumferential or vertical flow channels are made by machining the inner shell portion of the roll prior to applying the outer shell portion to the inner shell portion.

Various embodiments of the present invention are or are described only in connection with one or more aspects of the invention. It will be understood by those skilled in the art that any one aspect of the invention may be practiced alone or in combination with other embodiments in the same and other aspects of the invention.

In the following, the invention will be described with reference to the accompanying schematic drawings, but without limiting the invention exclusively to that shown in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a schematic drawing of the inner shell portion of a heat transfer roller according to an embodiment of the invention.

Fig. 2 shows some cross sections of the jacket of the heat transfer roller. DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description, like reference numerals designate like parts. It should be understood that the appended drawings are not to scale in their entirety and are intended primarily to illustrate embodiments of the invention.

Fig. 1 and Fig. 2 show the jacket 1 to be heated and / or to be cooled heat transfer roller. The shell 1 comprises an inner shell part 2 and an outer shell part 3, which is fixed by thermal shrinking on the inner shell part. On the inner shell part 2, longitudinal channels 4 are formed on the outer surface 6 as flow paths for the heat transfer medium. Further, vertical channels 5 for guiding the heat transfer medium from the inside of the inner shell part into the longitudinal channels 4 are formed on the inner shell part 2. In Fig. 1, the outer shell 6 to be shrunk onto the outer surface 6 of the inner shell part 2 is omitted. The outer shell part 3 is preferably made of metal, for example of steel, and has an outer surface for treating the fibrous web W. In the heat roller application, heat passes from the heat transfer medium through the outer shell part 3 to the fibrous web W, heat dissipates in the cooling roll application the fibrous web W through the outer shell part 3 on the heat transfer medium over.

If the outer casing part 3 is fastened on the inner casing part 2, then the longitudinal ducts 4 present on the outside of the inner casing part form flow channels for the heat transfer medium between the casing parts.

As a heat transfer medium is preferably used at high temperatures use of the oil. However, the heat transfer medium can also consist of water or steam or another suitable suitable for heat transfer liquid or gaseous medium.

The heat transfer roller comprises at each end of the shell one (preferably on the inner shell part 2 attached, omitted in the drawings) front part, which preferably has a flange, for example, by screws and positive fit at the shell end 7 via threaded holes. 8 is attached. The front part can also be attached in other ways. The heat transfer medium is conducted through the front part on the inside of the inner shell part 2 of the heat transfer roller, 4/8 Austrian Patent Office AT 13 495 Ul 2014-01-15 see arrow 9.

The heat transfer roller 1 has inside the inner shell part flow arrangements for conveying the heat transfer medium into the longitudinal flow grooves 4, i. in the longitudinal channels. The heat transfer medium flow arrangements to the longitudinal flow direction grooves 4 heating the outer shell portion can be realized independently of the end portions, which can then simplify the manufacture of the end portion and reduce the problems due to heating of the end portion.

The vertical channel 5 may also extend in a direction deviating from the radial direction of the roller.

Vertical channels 5 are used firstly for conducting heat transfer medium from the interior of the inner shell part 2 into the longitudinal channels 4 and secondly for returning heat transfer medium from the longitudinal channels 4 into the interior of the inner shell part 2.

In dashed rimmed area A (in the longitudinal direction in the middle of the shell part of the roller), the vertical channels 5 are used for conducting heat transfer medium to the outside of the inner shell part 2, from where the heat transfer medium continues through longitudinal channels 4 from the mantel center toward the Mantle front sides and further over located near the end faces vertical channels 5 back into the interior of the inner shell part 2 flows.

The vertical channels 5 may be intentionally scattered in the roll longitudinal direction to increase or decrease the desired heat transfer effect, for example, to reduce the effect of the vertical channels 5 possibly forming annular heat zone or to expand the increasingly heated area , For example, in the end face region of the inner shell part, adjacent vertical channels may be arranged in flow communication vertical channels for reducing the local heating effect in different longitudinal positions.

In dashed rimmed area B of the vertical channel 5 is used to conduct heat transfer medium to the outside of the inner shell part 2, from where the heat transfer medium continues to flow via longitudinal channels 4 from the mantel center toward the mantle end faces, the flow in the vicinity of the End faces from the longitudinal channel 4 (for example, via the dashed line in Fig. 2 circular arc-shaped transverse channel 4 ') in another longitudinal channel 4 and further passed through this longitudinal channel 4 in the central region of the shell, where the flow through the vertical channel 5 back into the interior the inner shell part 2 is passed.

In the dashed rimmed area C located on the front side vertical channels 5 are used to direct heat transfer medium from the inside of the inner shell part 2 on the outside, from where the heat transfer medium continues to flow via longitudinal channels 4 from the shell end side to the middle of the mantel, from where the heat transfer medium is passed through vertical channels 5 back to the inside of the inner shell part 2.

In dashed rimmed area D of the vertical channel located in the middle 5 is used for conducting heat transfer medium from the inside of the inner shell part 2 on the outside, from where the heat transfer medium continues through a longitudinal channel 4 in the direction of the mantle end sides and cross channels. 4 '(illustrated in Fig. 2) flows in the lateral direction transverse in one or more other longitudinal channels 4, through which the heat transfer medium is passed through a plurality of vertical channels 5 back into the inner shell part 2.

Fig. 2 shows some preferred embodiments for directing the flow from the interior of the inner shell part 2 to the outside thereof. In Fig. 2, the jacket is divided into three sectional sectors I, II and III, with which various embodiments are illustrated in the same drawing. The heat transfer roller preferably comprises a flow distributor 10 with an inner surface 10 '. The flow distributor 10 is installed inside in the inner shell part. With the flow distributor 10 of the heat transfer medium flow to the vertical channels 5 and the return from the vertical channels 5 are directed.

In the cross-sectional sector I, the flow distributor 10 forms a displacement body in such a way that a flow space 11 forms between the distributor and the inner jacket part. There is free flow connection between the flow space 11 and the vertical channels 5.

With the cross-sectional sectors II and III specifically such manifolds 10 are illustrated with which a directional flow connection to each desired vertical channels 5 can be made. In addition to the illustrations shown in the diagram of Figure 2, such manifolds may consist of tubing, hoses, and, for example, lightweight box-type ductwork, each connecting desired vertical passages.

In the cross-sectional sector II 10 longitudinal distribution channels 12 and vertical distribution channels 13 are formed in the interior of the flow distributor, with which a flow connection to the outside of the distribution channels 12 is made. The heat transfer medium flow is distributed with the vertical distribution channels 13 targeted to each desired vertical channels 5.

In the cross-sectional sector III 10 distribution grooves 14 are formed on the outside of the flow distributor, with which a directional flow connection to each desired vertical channels 5 is made.

The passage of the heat transfer medium from a longitudinal channel 4 in one or more other longitudinal channels 4 can be realized with one or more formed on the outside of the 8 inner shell part 2 transverse channels 4 '. The crossflow may also be realized by directing the heat transfer medium flow first via a vertical channel 5 to the inside of the inner shell part 2 and then using the flow distributor 10 of any embodiment again to the outside of the inner shell part 2.

The outer shell part 3 of the heat transfer roller is substantially thin to ensure intensive heat transfer, specifically such that the heat transfer capacity is preferably 300-850 kW / m. This allows a specific output of 65-150 kW / m2 to be achieved. Such specific services have not been achieved with the previously known roller heating solutions.

According to one embodiment, condensing steam serves as the heating medium. The condensation of the steam can take place in the longitudinal channels 4. To collect the condensate serve (omitted in the drawings) arcuate grooves from which the condensate is sucked into the vertical channels 5. The longitudinal channels are incorporated into the outer side of the inner shell part, and the intersecting arcuate transverse grooves for the condensate are incorporated into the inside of the outer shell part, so are located on a more circular line and thus collect the condensate in an external recess of the longitudinal channels. 4

The invention is described above by way of example with reference to the accompanying drawings. The invention includes all embodiments, aspects and combinations thereof described in this document in such a way that the invention is limited solely by the appended claims. 6.8

Claims (7)

Austrian Patent Office AT 13 495 U1 2014-01-15 Claims 1. A roll or cylinder comprising a shell (1) consisting of an inner shell part (2) and an outer shell part (3), the latter being used to form a shell Flow space for the heat transfer medium is tightly joined to the inner shell part, and attached to the ends of the shell end portions for forming a Wärmeübertragungsme- dium supply channel and -Abführkanals on the roller, wherein the inner shell part (2) flow channels (4, 5) for the heat transfer medium, characterized in that the cylinder comprises longitudinal distribution channels (12), vertical distribution channels (13) and / or distribution grooves (14) for forming a directional flow connection for the heat transfer medium to one or more heat transfer medium flow channels (4, 5). 2. Roller or cylinder according to claim 1, characterized in that on the outer side of the inner casing part (2) longitudinal flow channels (4) are formed. 3. roll or cylinder according to claim 2, characterized in that on the outer side of the inner shell part (2) arcuate flow channels (4 ') are formed to form a flow connection for the heat transfer medium between two or more longitudinal flow channels (4). 4. Roller or cylinder according to one of claims 1 to 3, characterized in that the inner shell part (2) has vertical channels (5) for forming a flow connection for the heat transfer medium between the inside and the outside of the inner shell part (2). 5. roll or cylinder according to claim 4, characterized in that the vertical channel (5) of the radial direction of the jacket (1) is designed differently. 6. Roller or cylinder according to one of claims 1 to 5, characterized in that the roller or the cylinder in the interior of the inner shell part (2) has a flow distributor (10), which longitudinal distribution channels (12), vertical distribution channels (13) and Distribution grooves (14) for forming a directional flow connection for the heat transfer medium to one or more vertical channels (5). Roller or cylinder according to one of claims 1 to 6, characterized in that the outer shell part (3) of the roller or cylinder is substantially thin so as to ensure intensive heat transfer such that the heat transfer capacity is 300-850 kW / m. 1 sheet of drawings 7/8