FI124999B - Ajettavuuskomponentti, järjestelmä ja menetelmä paperirainan kuivattamiseksi - Google Patents

Description

RUNNABILITY COMPONENT, ARRANGEMENT AND METHOD FOR DRYING A PAPER WEB

The invention relates to a runnability component, an arrangement and a method for drying a paper web according to the preambles of the enclosed independent claims.

In a drying section of a paper or board machine the web to be dried is conveyed supported by one or two wires in contact with a plurality of heated drying cylinders. In single-felting the paper web runs supported by a drying wire or fabric through a drying cylinder group so that the drying wire presses the web against the heated cylinder surfaces of the drying cylinders. Thus, in single-felting the drying cylinders are arranged outside the wire loop, and turn rolls are arranged inside the loop. A pocket space is formed, which is defined by the wire/fabric and two adjacent drying cylinders and the turn roll situated between the drying cylinders at a different level. An opening nip, or opening gap, is formed on the entry side of the pocket space on an area where the drying wire/fabric separates from the first drying cylinder and, correspondingly, a closing nip, or a closing gap, is formed on the entry side of the pocket space when the wire/fabric runs to the turn roll. In a similar manner, when the wire leaves the turn roll, an opening nip, i.e. an opening gap, is formed on the exit side of the pocket space and, correspondingly, when the wire runs to the adjacent, second drying cylinder, a closing nip, i.e. a closing gap, is formed on the exit side between the wire and the second drying cylinder.

Runnability problems occur, when the paper web has a tendency to detach, at certain points, from the contact with the drying wire. Problematic points are especially the above described opening nips, i.e. points where the web and the wire disengage from the drying cylinder surface. Up to that point, the web has travelled between the wire and the cylinder, and when the wire detaches from the cylinder, the web tends to follow the cylinder surface and thereby to disengage itself from the wire. Similar problems occur at closing nips, where the web and the wire are brought into contact with the turn roll surface. At that point, the web tends to disengage from the wire due to an overpressure formed in the nip.

Different kinds of runnability components, such as suction boxes or blow boxes, are arranged in the pocket space between the succeeding drying cylinders and the turn roll. Runnability components are used to create suitable underpressure in the pocket space, which promotes the keeping of the web in contact with the wire and improves the runnability of the dryer section of a paper machine. Blow boxes remove air from the pocket space by blowing action and they are typically used in connection with grooved and drilled vacuum suction rolls, where the air is sucked into the roll through holes in the roll shell. The suction is created by using a vacuum forming device, such as a fan or the like, which is arranged in connection with the interior of the roll. The underpressure inside the vacuum suction roll is typically about 2000 - 2500 Pa. On the other hand, suction boxes remove air from the pocket space by suction and they are typically used with so-called passive turn rolls, which have cut-outs in the roll shell. Suction box, which is arranged in the pocket space at the portion of the turn roll free from the wire, is arranged to suck air through the cut-outs of the turn roll. The interior of the passive turn roll has normally no direct connection with the vacuum forming devices.

The publications EP1194641, EP0787854, EP2135994 and WO82/02938 present some known runnability components for a drying section of a paper machine.

Savings in energy consumption is one of the goals when papermachine drying sections are renewed and rebuilt. A decrease in the amount of air that is blown and/or sucked through different runnability components, as well as a more accurate air flow control, would provide possibilities to reduce the energy consumption in the drying section. When rebuilding, it would be also advantageous to reuse existing runnability components, structures and pipelines as much as possible. At the same time a sufficient underpressure in the pocket space must be attained in order to avoid runnability problems.

An object of this invention is to minimise or even totally eliminate the disadvantages existing in the prior art.

An object is also to provide a runnability component with which a good underpressure can be created in the pocket space. A further object of the invention is to provide a runnability component enabling good control of the underpressure in the pocket space.

Another object of the invention is to provide a runnability component which enables the decrease in the amount of used air, and thus an indirect decrease in the amount of consumed energy.

These objects are attained with the invention having the characteristics presented below in the characterising parts of the independent claims.

Typical runnability component according to the present invention for a drying section of a paper machine is defined in claim 1 and it comprises - an entry side and an exit side, which are connected to each other at least by a lower surface, whereby the entry side, exit side and lower surface delimit the inner volume of the box-like elongated runnability component, - a first end and a second end, between which the runnability component extends in its length direction, - a first mechanical sealing element, which is arranged in connection with the surface of the entry side, - a second mechanical sealing element, which is arranged in connection with the surface of the entry side, beneath the first sealing element, and - a suction element, which is arranged in connection with the surface of the entry side, between the first and the second sealing elements.

Typical arrangement according to the present invention for a drying section of a paper machine or the like comprises - a suction roll, which has cut-outs, such as perforations, and - a runnability component according to the invention, arranged at least partially around the surface of the suction roll.

Typical method according to the present invention for drying a paper web or the like in a drying section of a paper machine is defined in claim 15 and it comprises - supporting a paper web with a drying wire, - guiding the paper web over a part of a heated surface of a first drying cylinder, turning travel direction of the paper web by using a suction roll, and guiding the paper web over a part of a heated surface of a succeeding second drying cylinder, - arranging, at least partly, a box-like elongated runnability component, extending over the width of the paper web, to a pocket space defined by the first and second drying cylinders, arranged parallel at a distance from each other, and the suction roll arranged between the first and second drying cylinders, parallel with them and having its axis of rotation on a different level from the axis of the first and second drying cylinder, the pocket space having an entry side on the side of the first drying cylinder and an exit side on the side of the second drying cylinder, - removing air from the space between the runnability component and the suction roll by suction into the suction roll, - sealing the space between the paper web and the surface of runnability component on the entry side by arranging a first mechanical sealing element in connection with the surface of the entry side and a second mechanical sealing element in connection with the surface of the entry side beneath the first sealing element, and - removing air by suction with a suction element, which is arranged in connection with the surface of the entry side, between the first and second sealing element.

The embodiments mentioned in this text relate, where applicable, to the runnability component, the arrangement as well as to the method according to the invention, even if this is not always separately mentioned.

Now it has been surprisingly found out that the air consumption in the drying section may be significantly decreased if two mechanical sealing elements are arranged on the entry side of the runnability component, in vicinity of the opening nip, and air is removed by suction with a suction element between these mechanical sealing elements. A sufficient underpressure can thus be created without blowing elements, which decreases the overall air flow and energy consumption. Furthermore, the suction element located between the mechanical sealing elements may be connected to existing suction devices which decrease rebuilding and renewal costs.

In context of the present application the pocket space is defined by the first and second drying cylinder and a suction roll between them. The drying cylinders are parallel, i.e. their longitudinal axes are parallel with each other, and they are arranged at a distance from each other. Typically the adjacent drying cylinders are arranged horizontally on the same level and the suction roll is arranged between the two adjacent drying cylinders so that the longitudinal axis of the suction roll is substantially parallel with the longitudinal axes of the drying cylinders, but located on a different level in the vertical direction than the axes of the drying cylinders. Suction roll is thus arranged on a higher or lower level than the drying cylinders, typically on a lower level. Furthermore, the suction roll is placed between the drying cylinders so that its surface does not touch the surfaces of the drying cylinders, i.e. is free from contact with the drying cylinder surfaces. In a typical paper machine the box-like runnability component, the drying cylinders and the suction rolls are elongated in the cross direction of the paper machine or the like, and extend substantially over the entire width of the web run. The pocket space is naturally also elongated in the cross direction of the paper machine. The ends of the pocket space are typically sealed, for example by means of end plates according to prior art, such as gap plates. The vertical end plates are arranged in machine direction, on both ends of the pocket space.

In this application, the entry side and the exit side of the pocket space have the following meaning. The pocket space may be divided, in machine cross direction at its centre point, by an imaginary vertical level having the width of the web run into an entry side and an exit side. On the entry side, i.e. between the first drying cylinder and the suction roll, and on the exit side, i.e. between the suction roll and the second drying cylinder, the pocket space is delimited by the wire or fabric, and therefore, during the operation of the paper machine, also by the web path formed by the wire/fabric and the web. The lower surface of the runnability component means the surface of the runnability component, which is located nearest to the suction roll, and which is arranged substantially towards the suction roll.

The runnability component comprises a first mechanical sealing element, which is arranged in connection with the surface of the runnability component on the entry side. The first mechanical sealing element is arranged at a short distance from the opening nip, between the wire and the cylinder, to project from the surface of the runnability component towards the wire.

The runnability component comprises also a second mechanical sealing element, which is arranged in connection with the surface of the runnability component on the entry side, beneath the first mechanical sealing element. The second mechanical sealing element is typically arranged at a distance of 30 - 200 mm, preferably 50 - 150 mm, more preferably 70- 130 mm from the first mechanical sealing element. Typically the second sealing element is arranged at the opening nip between the wire and the cylinder, to project from the surface of the runnability component towards the wire.

The first mechanical sealing element and/or second mechanical sealing element may be a sealing strip or a labyrinth sealing, such as single-chambered labyrinth sealing or multi-chambered labyrinth sealing. The material of the first and/or second mechanical sealing element may be, for example, Teflon®, plastic, rubber, composite or metal, such as steel or aluminium. A requirement for the sealing element material is a sufficient rigidity, with which the free flow of air may be prevented. The first mechanical sealing element and the second sealing element may be similar to each other or they may be different from each other. For example, the first mechanical sealing element may be a single-chambered labyrinth sealing and the second mechanical sealing element may be a multi-chambered labyrinth sealing. According to one embodiment the first mechanical sealing element and the second mechanical sealing element are both multi-chambered labyrinth sealings. By selecting the material and/or structure of the first and second mechanical sealing elements it is possible to optimise the sealing effect at the opening nip on the entry side of the runnability component.

According to one embodiment of the invention the first mechanical sealing element and/or second mechanical sealing element is provided with means for adjusting the distance of the sealing element(s) to the wire and the first drying cylinder. Thus the length of the mechanical sealing element extending outwardly from the entry side surface of the runnability component may be adjusted with the adjusting means. For example, the distance between the first drying cylinder surface and the second mechanical sealing element may be adjusted according to the needs of the process situation, and air may be leaked from the pocket space to the first suction zone between the first and second mechanical sealing element, if need be. This allows for better control of the underpressure in the pocket space and improves the runnability and energy economy.

The first and second mechanical sealing elements are preferably elongated in the cross direction of the paper machine or the like and extend substantially over the entire width of the web run. According to an embodiment of the invention, the first and/or second mechanical sealing are formed of at least two parts, preferably of several parts, in the lateral direction of the machine. Thus their mounting, transportation and storage is easier. A suction element is arranged in connection with the entry side surface of the runnability component, between the first and second sealing elements. The suction element removes air from a first suction zone, which is the area near the opening nip on the entry side, from the space between the wire and the surface of the runnability component. The suction element is connected to a suction channel, extending from the first end of the runnability component to the second end of the runnability component, and arranged inside the runnability component.

The suction element may be formed by at least one suction gap or by at least one row of suction holes, extending from the first end of the runnability component towards the second end, preferably to the second end, of the runnability component. The suction holes may have a diameter of 10 - 50 mm, preferably 15 - 30 mm, and the distance between two adjacent holes in a row is typically 20 -200 mm, preferably 30- 100 mm. The form of the suction holes may be selected freely, for example they may be circular or oval-shaped. The suction element may also comprise a plurality of adjacent suction gaps or a plurality of adjacent rows of suction holes. For example, the suction element may preferably comprise 2-4 adjacent rows of suction holes or adjacent suction gaps. Distance of the adjacent rows or gaps from each other is typically in the range of 5 - 35 mm.

In case the suction element comprises one or several uniform suction gaps, the width of an individual gap is 2 - 15 mm, typically 2-8 mm, preferably 2-6 mm.

The runnability component normally comprises a suction channel extending from the first end to the second end of the runnability component. The suction channel is arranged inside the runnability component, inside the space, which is defined by the outer walls of the runnability component. According to one embodiment of the invention the runnability component comprises a tapering suction channel extending from the first end to the second end of the runnability component. Tapering suction channel is advantageous as it enables the keeping of the underpressure on even level along the length of the channels, in cross direction of the paper machine. The suction element is in connection with the suction channel, which in its turn is usually arranged in contact with an external suction or vacuum device.

According to one embodiment of the invention the suction through the suction element on the entry side of the runnability component may be controlled according to the requirements of the process parameters, such as web speed, web tension or weight of the paper web which is produced. For example, the suction element may be connected to a connection, which is provided with a damper with which the direct suction from the negative pressure space between the entry side of the runnability component and the wire may be adjusted. Alternatively, the suction through the suction element may be controlled or adjusted by using a damper arranged in connection with the suction channel. It is also possible to adjust the suction of the suction element by adjusting the size of the suction holes or the width of the suction gap with adjustment means. The adjustment means may be, for example, a movable hole plate, which is arranged on top of the suction hole row in the cross direction of the paper machine. When the holes of the hole plate and the suction holes completely overlap, the suction is as the strongest. When the hole plate is moved, the overlap of the holes of the hole plate and the suction holes decrease, and the suction through the suction holes is reduced.

The suction element or the suction channel may be connected to an external suction device or vacuum air system, such as vacuum air system of the suction roll. This means that it is possible to connect the suction element, directly or indirectly, to existing suction air systems intended for creating an underpressure to the pocket space or to the suction roll. This is advantageous when existing paper machine drying sections are rebuilt, as no new suction systems need to be built, which saves time, costs and usually also space. The suction element may be connected to the external suction device or vacuum air system with a connection, which is provided with a regulating means for regulating the air flow, such as valve, damper or a throttle. The regulating means may be automatically adjustable or they may be adjustable manually. Thus the suction of the first suction means may be adjusted and optimised according to the process parameters and/or process situation.

The suction roll, which is used in the arrangement according to the present invention, has cut-outs, such as perforations, on its peripheral or circumferential surface. The suction roll may be a perforated suction roll, a grooved suction roll or a suction roll provided with both perforations and grooves. According to one embodiment of the present invention the suction roll has an open area of at least 0.5 %, typically 1 - 5 %, more typically 1.5-4 %, and it is connected to an external suction device or vacuum air system.

According to one preferred embodiment of the present invention the turn roll is a grooved suction roll. Possible grooving is typically arranged perpendicularly with respect to the axis of the roll, i.e. arranged to travel around the periphery of the roll. The width of the grooves is typically 3-8 mm, preferably 4-7 mm, and their depth is about 2-6 mm, preferably about 3-5 mm. The distance between adjacent grooves is typically 10-25 mm, preferably 12-20 mm. In an embodiment, the suction roll is grooved and perforated, i.e. the jacket of the roll is provided with cut-outs or openings and grooves. The grooves are preferably arranged to travel via the openings, whereby the advantage is achieved that the suction effect spreads in the groove on the area of the periphery, over a long distance and area, thereby intensifying the adhesion between the paper and the roll. According to one preferred embodiment of the present invention the grooved suction roll has an open area of at least 0.1 %, preferably 0.15 - 1.0 %, more preferably 0.2 - 0.4 %, and it is connected to an external suction device or vacuum air system.

The suction roll is used to create an underpressure in the second suction zone, which is the space between the lower part of the runnability component and the suction roll. The underpressure in the second suction zone is created by means of an underpressure prevailing inside the turn roll, which underpressure is effective through the cut-outs on the entire periphery of the roll. Thus, a higher underpressure is created inside the suction roll and an air flow is created towards the inside of the suction roll. The underpressure in the suction roll may be created by using internal or external suction devices or vacuum air system. According to an embodiment of the invention, the suction roll is connected to the external suction device or vacuum air system with a connection, which is provided with a regulation means for regulating the air flow, such as valve, damper or a throttle.

In this application, a higher underpressure means a lower absolute pressure. Respectively, a lower underpressure means a higher absolute pressure. An underpressure means a pressure, which is lower than the normal atmospheric pressure ca. 1 bar, i.e. 100 kPa. Typically the underpressure in the pocket space is < 400 Pa, typically 150 - 350 Pa. This means that the pressure in the pocket space is reduced with less than 400 Pa, typically 150 - 350 Pa from the normal prevailing atmospheric pressure. Typically the underpressure in the first suction zone near the opening nip at the entry side is < 1800 Pa, typically 500 - 1500 Pa This means that the pressure in the first suction zone is reduced with less than 1800 Pa, typically 500 - 1500 Pa from the normal prevailing atmospheric pressure.

According to one embodiment of the invention the arrangement comprises means for measuring the suction from the suction roll and/or from the suction element of the runnability component. When the suction air flow, which is removed from the suction element and/or suction roll, is measured, the different underpressure and/or suction zones may be controlled more accurately and carefully optimised. It is even possible to arrange a control system that controls and/or changes the different suction flows through the suction element and/or the suction roll on basis of the measurement results. For example, if the suction flow to the suction roll increases, it is possible to increase or decrease the suction through the suction element in the same proportion or by using a predetermined coefficient. Thus, the suction air flow from the suction element and/or the suction roll is measured, and, optionally, the suction through the first suction means and/or the suction roll is controlled on basis of the measurement results.

According to one embodiment of the invention the suction roll and the suction element of the runnability component are connected to the same external suction device or vacuum air system. The external suction device or vacuum air system may be an existing external suction device or vacuum air system, which is already present in the paper mill. It has been observed that the first and second mechanical sealing elements, as well as an additional sealing member, provide such an effective sealing of the pocket space that the suction element of the runnability component may be connected, for example, to an existing external suction device of the suction roll. The suction provided by the external suction device is strong enough for providing a sufficient underpressure both at the opening nip on the entry side and the space between the runnability component and the suction roll. Use of only one external suction device and or vacuum air system makes it possible to minimise the need for rebuilding when renewing the drying section and saves also valuable mill space.

According to one preferred embodiment of the invention the runnability component further comprises at least one additional sealing member, possibly a plurality of additional sealing members, arranged in connection with the lower part of the runnability component, preferably with the lower surface of the runnability component. The additional sealing member is a mechanical sealing element, and it typically extends outwards from the lower part, preferably from the lower surface, of the runnability component, preferably towards the suction roll. The sealing member may be arranged to the lower surface of the runnability component on the exit side, or to the middle of the lower surface of the runnability component. According one preferred embodiment, the sealing member is arranged at at least one, preferably at both lower corners of the runnability component, extending towards the surface of the turn roll. The sealing member(s) serve(s) as a concrete physical obstacle(s) for the entry of air into the space between the runnability component and the suction roll. Thus, only a minute amount of air possibly enters into the said space. The sealing member seals the gap between the runnability component and the suction roll, in order to intensify the suction to the turn roll from the space between the lower surface of the runnability component and the turn roll.

The additional sealing member may be a sealing strip or a labyrinth sealing, such as single-chambered labyrinth sealing or multi-chambered labyrinth sealing. The material of the additional sealing member may be, for example, Teflon®, plastic, rubber, composite or metal, such as steel or aluminium. A requirement for the material is a sufficient rigidity, with which the free flow of air may be prevented.

According to one embodiment of the invention the additional sealing member is provided with means for adjusting the distance of the additional sealing member to the suction roll, whereby the length of the additional sealing member extending outwardly from the lower surface of the runnability component may be adjusted with the adjusting means. For example, the additional sealing member may be attached to a rotatable pipe, which is arranged in connection with the runnability component. When the pipe is rotated, distance between the additional sealing member end and the suction roll surface changes. Thus, the distance between the additional sealing member and the suction roll may be adjusted and the air leaked to the area between the lower surface of the runnability component and the suction roll. Sometimes the first and/or second mechanical sealing elements and additional sealing member(s) create such an effective sealing that the underpressure in the pocket space or at the opening nip is significantly enhanced. The location of the additional sealing member may then be adjusted further away from the suction roll, whereby a gap between the sealing member and the suction roll is formed or increased. From this gap air may be allowed to leak to the pocket space or to the space between the lower surface of the runnability component and the suction roll from the opening nip on the exit side.

According to another embodiment of the invention the runnability component may comprise also a sealing blow nozzle, arranged in the connection with the exit side of the runnability component, i.e. on the side of the opening nip from the suction roll, and delimiting the air flows on the exit side. The control of the underpressure in the pocket space between the drying cylinders and the suction roll may be improved with the exit side sealing blow nozzle, with which air is ejected out of the pocket space and/or the entry of the air into the pocket space via the gap between the exit side of the runnability component and the second drying cylinder is prevented. Typically, no additional sealing member is arranged on the exit side of the lower part of the runnability component, in case the sealing blow nozzle is used. An additional sealing member may be arranged in the middle of the lower surface or on the entry side of the lower surface of the runnability component, in case the exit side comprises a sealing blow nozzle.

According to one embodiment of the invention the runnability component comprises further a tail threading zone. The tail threading zone may be located, with respect to the web run, on the tending side and/or on the driving side, in the area of the first end and/or the second end of the runnability component. During tail threading the suction force in the tail threading zone may be controlled into one value and after the tail threading, i.e. in a normal running situation with a wide web run, to a second value. The tail threading zone is defined by a dividing wall arranged inside the runnability component, dividing the suction channel in a tail threading zone and normal operation zone. The dividing wall is normally vertical and it is arranged perpendicular to the length axis of the runnability component, i.e. the dividing wall is vertical and arranged parallel with the machine direction and with direction of web movement. The adjustment of suction force between the tail threading zone and the normal operation zone may be achieved by appropriate control means. For example, the tail threading zone may be connected to a separate and individual suction means, which are controlled independently from the suction devices or the like that create the suction to the normal operation zone of the suction channel.

According to one preferred embodiment of the present invention the control of the suction force at the tail threading zone and at the normal operation zone is achieved by using an integrated control means. The integrated control means comprise a first and a second coaxial pipe with different diameter. The first pipe is in contact the suction element of the tail threading zone and the second pipe is in contact with the suction element of the normal operation zone. Both the first and the second pipe of the integrated control means are in contact with the suction device or vacuum air system. A damper is arranged to the second pipe, so that the air flow through it may be restricted or totally terminated. When the damper is open, the suction is evenly divided to both the first and the second pipe, and the suction through suction element on the tail threading zone is equal to the suction through the suction element on the normal operation zone. When the damper is partially or wholly closing the second pipe, the suction is mainly or only occurring through the first pipe, i.e. mainly or only through suction element on the tail threading zone. According to one preferred element the cross section of the first pipe is circular and cross section of the second pipe is angular, preferably rectangular.

The invention is described in more detail below with reference to the enclosed schematic drawings, in which

Figure 1 shows a schematic view of a pocket space between two drying cylinders and one turn roll,

Figure 2 shows an arrangement according to a first embodiment of the present invention,

Figure 3 shows an arrangement according to a second embodiment of the present invention, and

Figure 4 shows an arrangement according to a third embodiment of the present invention.

Figure 1 shows a schematic general view of a pocket space 9 between two drying cylinders 1, 2 and one turn roll 3 in the drying section of a paper machine. The pocket space 9 is delimited by a first drying cylinder 1, a second drying cylinder 2, a turn roll 3 and a web run 5a, 5b. Described more in detail, the pocket space 9 is delimited, on its entry side 9a, by a web run 5a between the first drying cylinder 1 and the turn roll 3, and on the exit side 9b of the pocket space, by a web run 5b between the turn roll 3 and the second drying cylinder 2. The location of the turn roll in a horizontal direction x and in a longitudinal direction L of the paper machine is between the drying cylinders 1, 2, but in a vertical direction y lower than said cylinders 1, 2. The directions of rotation of the cylinders 1, 2 are shown by arrows R. It is to be understood, that the above-presented arrangement is repeated by its substantial parts in the drying section of a paper or a board machine.

Figure 1 also shows - an opening nip 7a of the first drying cylinder 1 on the entry side 9a, i.e. the point where the wire and the web detach from the periphery of the first drying cylinder 1 towards the turn roll 3, - a closing nip 8a of the turn roll 3 on the entry side 9a, i.e. the point where the wire enters into connection with the turn roll 3 after the first drying cylinder 1, - an opening nip 8b of the turn roll 3 on the exit side 9b, i.e. the point where the wire detaches from the periphery of the turn roll 3 towards the second drying cylinder 2, and - a closing nip 7b of the second drying cylinder 2 on the exit side 9b, i.e. the point where the wire and the web enter into connection with the second drying cylinder 2 after the turn roll 3.

Figure 2 shows an arrangement according to a first embodiment of the present invention. A runnability component 10 is arranged in connection with a pocket space between the drying cylinders 1, 2 and the suction turn roll 3 of a paper machine. The entry side 10a of the runnability component 10 is provided with a first mechanical sealing element 20, and a second mechanical sealing element 20'. Sealing elements 20, 20' may be as a labyrinth seals. The first and second mechanical sealing elements 20, 20' are arranged in connection with the surface of the entry side 10a of the runnability component 10 and in vicinity of the opening nip 7a between the runnability component 10 and the first drying cylinder 1. The second mechanical sealing element 20' is arranged beneath the first mechanical sealing element 20, at a distance from it. The negative pressure space on the entry side of the pocket space is divided into an intensified first negative pressure space 91 and a second negative pressure space 92. A suction element 31 is arranged on the entry side 10a of the runnability component 10, between the first mechanical sealing element 20 and the second mechanical sealing element 20'. The suction element 31 may comprise, for example, three parallel rows of suction holes, through which the air is sucked from the intensified first negative pressure space or first suction zone 91. A suction channel 32 is arranged inside the runnability component 10. The air flows are indicated with arrows.

The suction created by the suction roll 3 removes air from the space 93 between the lower part of the runnability component and the suction roll 3, through cut-outs or perforations on the surface of the suction roll 3.

Additional sealing members 19, 19', such as sealing strips are arranged in connection with the lower part of the runnability component 10. Additional sealing members 19, 19' define a second suction zone 93 between the lower surface of the runnability component 10 and the suction roll 3. The additional sealing member 19' guides also the air flow 16 so that it does not enter the suction zone 93 but is guided after the opening nip 8b of the turning suction roll 3 on the exit side away from the pocket space in the direction of the web run 5b.

Figure 3 shows an arrangement according to a second embodiment of the present invention. In a similar manner as in Figure 2 a runnability component 10 is arranged in connection with a pocket space between the drying cylinders 1, 2 and the suction roll 3 of a paper machine. The structure of the runnability component 10 corresponds generally to that what is presented in Figure 2, except that the runnability component 10 comprises one additional sealing member 19, such as sealing strip, which is arranged in connection with the lower part on the entry side 10a of the runnability component 10. Furthermore, a sealing blow nozzle 15 is arranged on the exit side 10b of the runnability component 10. The exit side blow nozzle 15 blows air in the travelling direction of the web run 5b according to arrow 14, and thereby ejects air away from the pocket space and prevents the air from entering into the pocket space via the gap between the exit side 10b of the runnability component 10 and the second drying cylinder 2.

Figure 4 shows an arrangement according to a third embodiment of the present invention. The runnability component 10 is located in the pocket space between first drying cylinder 1, second drying cylinder 2 and suction roll 3. The suction connection 40 of the suction roll and the suction connection 41 of the runnability component are connected to the same external suction device (not shown). The suction connections 40, 41 may be provided with regulation means, such as valve or a throttle, for regulating the air flow.

Even if the invention was described with reference to what at present seems to be the most practical and preferred embodiments, it is appreciated that the invention shall not be limited to the embodiments described above, but the invention is intended to cover also different modifications and equivalent technical solutions within the scope of the enclosed claims.

Claims (18)

1. Ajettavuuskomponentti paperikoneen tai vastaavan kuivatusosaa varten, käsittäen - tulopuolen (10a) ja jättöpuolen (10b), jotka ovat yhteydessä toisiinsa ainakin alapinnan välityksellä, jolloin tulopuoli (10a), jättöpuoli (10b) ja alapinta rajaavat laatikkomaisen, pitkänomaisen ajettavuuskomponentin (10) sisätilavuuden, ajet-tavuuskomponentin (10) alapinnan sijaitessa lähimpänä imutelaa (3) ja ollessa järjestetty oleellisesti kohti imutelaa (3), - ensimmäisen pään ja toisen pään, joiden välillä ajettavuuskomponentti (10) ulottuu pituussuunnassaan, - ensimmäisen mekaanisen tiivistyselimen (20), joka on järjestetty tulopuolen (10a) pinnan yhteyteen, - toisen mekaanisen tiivistyselimen (20’), joka on järjestetty tulopuolen (10a) pinnan yhteyteen ensimmäisen tiivistyselimen (20) alapuolelle, ja - imuelimen (20’), joka on järjestetty tulopuolen (10a) pinnan yhteyteen, ensimmäisen ja toisen tiivistyselimen (20, 20’) väliin, tunnettu siitä, että ensimmäinen mekaaninen tiivistyselin (20) ja toinen mekaaninen tiivistyselin (20’) on labyrinttitiiviste, kuten yksikammioinen labyrinttitiiviste tai monikammioinen la-byrinttitiiviste ja että ensimmäiseen ja toiseen mekaaniseen tiivistyselimeen (20, 20’) on järjestetty välineet tiivistyselinten (20, 20’) etäisyyden säätämiseksi viirasta ja ensimmäisestä kuivatussylinteristä (1) prosessitilanteen tarpeiden mukaan ja ilman vuotamiseksi taskutilasta ensimmäisen ja toisen mekaanisen tiivistyselimen (20, 20’) väliselle ensimmäiselle imuvyöhykkeelle.

2. Patenttivaatimuksen 1 mukainen ajettavuuskomponentti, tunnettu siitä, että se käsittää ainakin yhden lisätiivistyselimen (19, 19’), joka on järjestetty ajettavuuskomponentin (10) alaosan yhteyteen ja joka on mekaaninen tiivistyselin.

3. Patenttivaatimuksen 1 tai 2 mukainen ajettavuuskomponentti, tunnettu siitä, että lisätiivistyselin (19, 19’) on tiivistyslista tai labyrinttitiiviste, kuten yksikammioi-nen labyrinttitiiviste tai monikammioinen labyrinttitiiviste.

4. Patenttivaatimuksen 3 mukainen ajettavuuskomponentti, tunnettu siitä, että lisätiivistyselimeen (19, 19’) on järjestetty välineet tiivistyselimen (19, 19’) etäisyyden säätämiseksi imutelasta (3).

5. Patenttivaatimuksen 1 mukainen ajettavuuskomponentti, tunnettu siitä, että se käsittää tiivistävän puhallussuuttimen (15), joka on järjestetty ajettavuuskom-ponentin (10) jättöpuolen (10b) yhteyteen.

6. Patenttivaatimuksen 1 mukainen ajettavuuskomponentti, tunnettu siitä, että imuelin (31) on muodostettu ainakin yhdestä imuraosta tai ainakin yhdestä rivistä imuaukkoja, ulottuen ajettavuuskomponentin (10) ensimmäisestä päästä kohti ajettavuuskomponentin (10) toista päätä.

7. Patenttivaatimuksen 1 mukainen ajettavuuskomponentti, tunnettu siitä, että imuelin (31) on liitetty ulkoiseen imulaitteeseen tai tyhjiöjärjestelmään.

8. Patenttivaatimuksen 7 mukainen ajettavuuskomponentti, tunnettu siitä, että imuelin (31) on liitetty ulkoiseen imulaitteeseen tai tyhjiöjärjestelmään liitoksella, jossa on ilmavirran säätämiseksi säätöelin, kuten venttiili tai kuristin.

9. Järjestely paperikoneen tai vastaavan kuivatusosaa varten, käsittäen - imutelan (3), jossa on reikiä, kuten lävistyksiä, ja - jonkin patenttivaatimuksen 1 - 8 mukaisen ajettavuuskomponentin (10), joka on järjestetty ainakin osittain imutelan (3) pinnan ympärille.

10. Patenttivaatimuksen 9 mukainen järjestely, tunnettu siitä, että imutelan (3) avoin alue on ainakin 0,5 %, 1 - 5 %, tyypillisemmin 1,5-4 % ja se on liitetty ulkoiseen imulaitteeseen tai tyhjiöjärjestelmään.

11. Patenttivaatimuksen 9 mukainen järjestely, tunnettu siitä, että imutela (3) on uritettu imutela, jonka avoin alue on ainakin 0,1 %, edullisesti 0,15-1,0 %, edullisemmin 0,2 - 0,4 %, ja se on liitetty ulkoiseen imulaitteeseen tai tyhjiöjärjestel-mään.

12. Jonkin edeltävän patenttivaatimuksen 9-11 mukainen järjestely, tunnettu siitä, että imutela (3) on liitetty ulkoiseen imulaitteeseen tai tyhjiöjärjestelmään liitoksella, jossa on ilmavirran säätämiseksi säätöelin, kuten venttiili tai kuristin.

13. Jonkin edeltävän patenttivaatimuksen 9-12 mukainen järjestely, tunnettu siitä, että se käsittää välineet ajettavuuskomponentin (10) imutelan (3) ja/tai imuelimen (31) imun mittaamiseksi.

14. Jonkin edeltävän patenttivaatimuksen 9-13 mukainen järjestely, tunnettu siitä, että ajettavuuskomponentin (10) imutela (3) ja imuelin (31) on liitetty samaan ulkoiseen imulaitteeseen tai tyhjiöjärjestelmään.

15. Menetelmä paperirainan tai vastaavan kuivattamiseksi paperikoneen tai vastaavan kuivatusosassa, jossa menetelmässä - tuetaan paperirainaa kuivatusviiran avulla, - ohjataan paperiraina yli osasta ensimmäisen kuivatussylinterin (1) kuumaa pintaa, käännetään paperirainan kulkusuunta käyttäen imutelaa (3) ja ohjataan paperiraina yli osasta seuraavan toisen kuivatussylinterin (2) kuumaa pintaa, - järjestetään, ainakin osittain, paperirainan leveydelle ulottuva laatikkomainen pitkänomainen ajettavuuskomponentti (10) taskuillaan, jota rajaavat toisistaan välimatkan päähän yhdensuuntaisesti järjestetyt ensimmäinen ja toinen kuivatussylin-teri (1, 2) ja imutela (3), joka on järjestetty ensimmäisen ja toisen kuivatussylinterin (1, 2) väliin yhdensuuntaiseksi niiden kanssa ja siten, että sen pyörimisakseli on eri tasolla kuin ensimmäisen ja toisen kuivatussylinterin (1, 2) akseli, jossa taskuti-lassa (9) on tulopuoli (9a) ensimmäisen kuivatussylinterin (1) puolella ja jättöpuoli (9b) toisen kuivatussylinterin (2) puolella, jolla ajettavuuskomponentilla (10) on tulopuoli (10a), jättöpuoli (10b) ja alapinta, jotka rajaavat laatikkomaisen pitkänomaisen ajettavuuskomponentin (10) sisätilavuutta, ajettavuuskomponentin (10) alapinnan sijaitessa lähimpänä imutelaa (3) ja ollessa järjestetty oleellisesti kohti imutelaa (3), - poistetaan ilmaa imulla ajettavuuskomponentin (10) ja imutelan (3) välisestä tilasta (93) imutelaan (3), - tiivistetään paperirainan ja ajettavuuskomponentin (10) välinen pinta tulopuolella (9a) järjestämällä ensimmäinen mekaaninen tiivistyselin (20) ajettavuuskomponentin (10) tulopuolen (10a) pinnan yhteyteen ja toinen mekaaninen tiivistyselin (20’) tulopuolen (10a) pinnan yhteyteen ensimmäisen tiivistyselimen (20) alapuolelle, ja - poistetaan ilmaa imemällä imuelimellä (31), joka on järjestetty tulopuolen (10a) pinnan yhteyteen, ensimmäisen ja toisen tiivistyselimen (20, 20’) väliin, tunnettu siitä, että - säädetään ensimmäisen tiivistyselimen (20) ja toisen tiivistyselimen (20’) etäisyyttä ensimmäiseen kuivatussylinteriin (1) prosessitilanteen tarpeiden mukaan, tiivistyselimien (20, 20’) ollessa labyrinttitiiviste, kuten yksikammioinen labyrinttitii-viste tai monikammioinen labyrinttitiiviste, ja - vuodetaan ilmaa taskutilasta (9) ensimmäisen ja toisen mekaanisen tiivistyselimen (20, 20’) väliselle ensimmäiselle imuvyöhykkeelle.

16. Patenttivaatimuksen 15 mukainen menetelmä, tunnettu siitä, että imuelin (31) ja/tai imutela (3) liitetään ulkoiseen imulaitteeseen tai tyhjiöjärjestelmään liitoksella, jossa on ilmavirran säätämiseksi säätöelin, kuten venttiili tai kuristin.

17. Patenttivaatimuksen 15 tai 16 mukainen menetelmä, tunnettu siitä, että mitataan imuilmavirtausta imuelimestä (31) ja/tai imutelasta (3) ja, valinnaisesti, ohjataan ensimmäisen imuvälineen ja/tai imutelan (3) kautta tapahtuvaa imua mittaustulosten perusteella.

18. Jonkin edeltävän patenttivaatimuksen 15-17 mukainen menetelmä, tunnettu siitä, että tiivistetään ajettavuuskomponentin (10) ja kääntötelan (3) välinen rako ainakin yhdellä ajettavuuskomponentin (10) alaosan yhteyteen järjestetyllä lisätii- vistyselimellä (19, 19’), edullisesti usealla lisätiivistyselimellä, ja valinnaisesti säädetään lisätiivistyselimen (19, 19’) etäisyyttä kääntötelaan (3).