FI121277B - Apparatus and method for treating a fibrous web - Google Patents

Description

APPARATUS AND METHOD FOR HANDLING FIBER FIBER FIELD OF THE INVENTION

The invention relates to an apparatus and method for treating a fibrous web. More particularly, but not exclusively, the invention relates to the control of currents in the sink between a web and a movable support member supporting a web in connection with surface sizing or coating.

BACKGROUND OF THE INVENTION

A surface adhesive, a pigment and a coating material are applied to the surface of the fibrous web, such as paper and board, for example by spraying the moving material with spray nozzles directed to the web.

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In some processing devices, the spray nozzles are arranged to spray the processing agent on a fibrous web web through a chamber-like space.

A chamber-like space is formed inside the injection housing, in which the treatment zone is applied to the web and the resulting 20 treatment mist and air are removed from the injection housing by suction. The web can be treated by spraying treating agent on one or both sides of the web. After spraying with the treating agent, the web can be compressed in a press nip to enhance the absorption of the treatment agent.

25 This application relates to surface sizing, pigmentation and coating as well as calendering of fiber web and control of air and processing mist streams in a fiber web machine. In the following, the invention will be described with reference to spray sizing and coating as preferred embodiments of the invention.

Surface sizing can be carried out using, for example, a starch aqueous mixture which is applied by spray nozzles to the surface of the web and pressed into the web, for example in a nip between rollers. The diluent mixture may comprise many additives and binders. After the treatment agent is sprayed, the web is pressed in a press nip, the press member of which can be a belt in addition to the roll. Surface glue is used to increase the strength of the web. The surface adhesive also improves the surface properties and printability of the paper. For some board grades, the strength of the product is one of the most important characteristics of the product. Because surface sizing can improve the flexural and surface strength of a product, some products tend to use large amounts of sprayable curing agent.

10 As the yield requirements for paper and board manufacture increase, the speed of the line has been increased. As a result of the increase in velocity, the amount of air transported to the spray zone by the web and the surfaces of the movable pressing members, such as the roller surfaces, causes problems in removing the air to be removed from the spray housing and the spray mist. In addition, preventing the spray mist from leaking into the environment 15, for example sealing the spray housing, has proven difficult.

The spray mist may condense on the structures of the spray housing and fall into the web as drops, which may cause runnability problems and defects in the coating or adhesive layer of the web being treated. Getting drops of detergent into the web to be treated can lead to an error in the final product. The use of spraying equipment, especially at high driving speeds, causes environmental leaks of treatment agent. dirty hardware. Since the spray casing cannot be constructed to be completely airtight, the spray mist tends to escape even small gaps, such as the gap between the end of the movable pressing member and the spray casing.

FI20075348 discloses an apparatus for applying a treatment agent such as a surface adhesive to a surface of a fibrous web. The apparatus comprises at least one spray chamber opening towards the track, having an inlet slot for the track 30 and spray nozzles for applying the treatment agent. An exhaust duct is provided to remove air and curing agent mist from the spray chamber. A portion of the walls of the injection chamber are formed by web pressing members, such as rollers, through which the web is removed from the injection chamber.

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The known injection chamber discharge arrangement, particularly at high driving speeds, is not capable of sufficiently reducing the undesirable spread of spray agent mist formed in the injection chamber into the environment.

The fibrous web can be coated in a coating station, for example, by a blade coating technique. Particularly at high speeds, air conveyed by the surface of the moving web and the surface of the moving back roll is carried between the coating roll and the web. The phenomenon where the web is detached from the surface of the backing roll is called 10 sachets. The puncturing phenomenon is described in Fl 110956, in which the air located between the web and the counter roll prior to the coating layer smoothing affects the web distance from the appliance, causing variations therein and thereby coating problems such as uniformity of the coating, applicator nozzle. In Fl 110956 15, pouching is reduced by bringing the web into contact with the backing roll shortly before or even after application.

SUMMARY

According to a first aspect of the invention, there is provided an apparatus for treating a fibrous web comprising at least one support member supporting the fibrous web, the supporting member comprising a movable surface adapted to the fibrous web, and in use a supporting member and fibrous web. At least one end of the throat is provided with a flow outlet means 25.

In another aspect of the invention, there is provided a method of treating a fibrous web by supporting a movable fibrous web web with at least one support member comprising a movable surface to be fitted against the fibrous web and forming a sink between the web and the fibrous web.

The outlet means preferably comprises an outlet channel. The outlet means preferably comprises at least one of the following: a second outlet, a co-outlet, and a third outlet.

The flow can be removed at the level of the support member end or outside. 5 Flow removal may occur between the end of the support member and the edge of the web. The flow can be removed between the support member and the track.

The apparatus may comprise at least one injection chamber. The support member may comprise a press roll or a press belt or a corresponding press member 10 disposed in the injection chamber. The flow may comprise a mixture of air and a treatment agent. The air / treating agent mixture may be removed from the throat between the web and the press member from the injection chamber.

For each sink in the injection chamber, at least one discharge means may be provided for discharging the air / treatment mixture.

A common removal means may be provided for two adjacent sinks.

The outlet means preferably comprises a channel for establishing a flow connection to the suction source 20 of the outlet suction. The injection chamber may comprise a first outlet duct extending across the transverse length of the injection chamber. The channel may be arranged in flow communication with the suction source of the first outlet channel.

According to some embodiments, the support member comprises a counter roll and the flow 25 comprises air. Air can be removed from the throat between track and counter roll.

Overpressure in the pharynx can be reduced by removing lateral flow from the pharynx.

30 The removal of overpressure in the throat between the track and the track support member is very effective as it occurs in a high pressure zone with high flow velocities and laterally oriented in the discharge direction.

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In some embodiments, suctioning the exhaust means can collect fog that may otherwise leak into the environment at the edges of the nip, thereby improving environmental cleanliness. The condensation of the detergent mist 5 into droplets can be reduced by providing suction to the removal means.

Various embodiments of the present invention will be described or described only in connection with some or some aspects of the invention. One skilled in the art will appreciate that any embodiment of an aspect of the invention may be applied to the same and other aspects of the invention, alone or in combination with other embodiments.

BRIEF PRESENTATION OF THE PATTERNS

The invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which: Figure 1 is a side elevational view of a first fibrous web treatment device in which air is sprayed from a spray chamber on the first side of a web and a pressurized outlet between the web and a press roll; Figure 2 is a side elevational view of another fibrous web treatment device in which air and a spray mist are drawn from both sides of the web from the sides of overpressure sinks formed between the web and the pressing members 25; Figure 3 is a top view of the flow directions in the drain of Figure 1, the sides of which are provided with second outlet channels; and Fig. 4 is a side elevational view of a third fibrous web treatment device for sucking air from the sides of a sink formed between the web and the counter roll via third outlet channels.

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DETAILED EXPLANATION

Throughout the specification, like reference numerals refer to like parts. It should be noted that the figures shown are not in their entirety on a 5 scale, and that they serve primarily the purpose of illustrating embodiments of the invention.

The fibrous web web W is shown in the figure in the horizontal position, but the web W can be guided to the injection device 100 or the coating device 101 or other fibrous web processing device also in an inclined position or in an upright position. For purposes of simplicity of presentation, the invention is described in this specification when the web W is in a horizontal position.

Figure 1 illustrates an injection device 100 comprising a first injection case 1 on the first side 15 of the web W. The injection case 1 is arranged in connection with the fiber web W and the first press roll 21 such that the press roll 21 defines the injection chamber 5 to the right. The inner wall 8 of the injection housing 1 defines a first injection chamber 5 opening in the direction W of the track in Figure 1 to the left and up. Spray nozzles 6 are arranged to spray toward the treatment medium 7 in the spray web 5 moving web W. The web W is pressed in a press nip 23 between the web supporting press roll 21 and a second press member 22 beneath it. The first and second press members may be roll or belt or felt or similar. suitable support body.

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The injection chamber 5 comprises an air inlet 10 formed between a wall portion 11 between the front wall 14 and the inner wall 8 and a movable track W. The front wall 14 is connected to the top wall 15 which extends in the direction of the press roll 21. The top wall 15 is connected to the rear wall 9 near the press roll 21, which extends downwardly near the surface of the press roll 21. The rear wall 9 and the surface of the press roll 21 form a gap 20 between the inner wall 8, the wall section 11, the front wall 14, the top wall 15 and the rear wall 9 of the injection housing 1. Naturally, other functions may also be located within the area delimited by the walls of the injection housing 1, for example, spray treatment agent dispensers or flow chambers in accordance with prior art.

The rear wall 9 and the inner wall 8 form between them a first outlet duct 30 through which a flow connection to the outlet chamber 31 is formed through an outlet opening from the injection chamber 5. Preferably, the first outlet duct 30, in particular its inlet port, extends across the entire length of the injection housing 1 when viewed across the web.

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The track W conveys air through the inlet 10 to the injection chamber 5. The movable surface of the press roll 21 conveys air through the slot 20 to the injection chamber 5.

In Figure 1, air 3 and a spray mist 7 are drawn from the injection chamber 5 on the first side of the web W via the first outlet duct 30. The drain 24 formed between the web W and the press roll 21 has been found to develop at high speeds used for high pressure. It has been found that the first outlet duct 30, known per se, is not capable of adequately removing air and curing agent mist 3, 7 from throat 24. Thus, for controlling the air and curing mist flows 3, 7 in the overpressure zone formed in throat 24, , preferably at the ends of the press roll 21.

More generally, a flow outlet means 40 is disposed on the side of the drain 24 formed between the web W and the at least one support member 21 supporting the web. The second outlet channels 40 may be arranged outside the press roll 21 ends with a very small end slot 42 between the (Fig. 3) for preventing flow or by providing seals between the other outlet channels 40 and the ends 42 of the roller 21.

Air and treatment mist streams 3, 7 are led from sink 24 to other outlet channels 40, i.e. in the direction in which said streams are naturally otherwise directed from overpressure drainage zone 24. By suctioning into other outlet channels 40, mist can be collected which otherwise can leak into the environment environmental cleansing. Since the flow direction of the currents 3, 7 in the drain 24 does not need to be significantly changed, the energy of the exhaust is not consumed by this. Because of the significant lateral velocity of the streams, the streams 3, 7 may be allowed to travel in the upstream direction, so that the suction power and / or vacuum and / or volume flow of the other outlet ducts 40 need not be high to significantly reduce suction 24. In this case, the leakage of the treatment agent mixture can be reduced. According to some embodiments 10, the suction power of the first outlet channel 30 may even be reduced. According to some embodiments, the suction arrangement implemented in the second outlet ducts 40 can increase the processing speed of the web compared to prior art solutions without necessarily increasing the total suction power of the spraying apparatus 100 and without increasing leakage of the treatment agent mixture into the environment. According to some embodiments, the suction arrangement of the second outlet channels 40 may increase the amount of treatment agent applied to the web as a function of time.

The injection device 100 may comprise, in addition to the first injection housing 1, a second injection housing arranged on one side of the web W 20 for double-sided treatment of the web. The second injection case 2 may be a mirror image of the first injection case 1 as shown in Figure 2. With reference to Figure 2, reference is made to the description of Figure 1.

In Figure 2, air 3 and curing spray 7 are drawn from both sides of the web W from the sides of adjacent overpressure drains 24, 24 'formed between the web and the pressing members 21, 22. Track W separates adjacent sinks. For controlling the air and curing spray streams 3, 7 formed in the overpressure zone formed in the sinks 24, 24 ', co-discharge ducts 40' are provided at the sides of the sinks 24, 24 ', preferably at the ends of the pressing members 21, 22. The compression nipple portion above the web W is designated 23 and the compression nip portion 23 'below the web. Correspondingly, the first sink above the web W is labeled 24 and the second sink 24 'below the web. The common outlet duct 40 'may comprise a channel common to both sinks 9 24, 24' or may be provided with its own separately controlled second outlet duct 40. Thus, the first spray housing 1 may be provided with second outlet ducts 40 and separate second outlet ducts 40 fitted to the second injection housing 2 5 for the second drain 24 '. Each of the second outlet ducts 40 for the first sink 24 may be secured to and movable with the first injection housing 1, and respectively the second outlet ducts 40 for the second sink 24 'may be secured to and moved with the second injection housing 2.

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Figure 3 is a top view of the directions of flows of the air and treatment mist 3, 7, as shown by arrows, at the throat 24 of the injection housing 1 of Figure 1 formed by a rotary press roll 24 and a movable track W. The drain 24 terminates in the direction of travel of the web to the press nip 23 and the flow 3, 7 extends from the pressurized pressure zone 24 15 in each lateral direction as exemplified by the arrows. In the center of the web, the flow is directed in the opening direction of the pharynx 24, but in the periphery of the pharynx, the flow is naturally directed sideways.

The spillage of treating agent in the direction of the axes of the press rollers 20, which is characteristic of the known injection housing, can be reduced by providing at least one other outlet channel 40 from the sink for a lateral flow path 3, 7. According to some embodiments, the known injection box may be modified by inserting an opening on the side of the sink 24, for example, in the end region of the pressing member, for a second outlet conduit 40. The second outlet duct 40 comprises a suction opening on the side 25 of the sink 24 through which the sink 24 is connected to the suction source via a channel 41 (not shown). The suction source may be the same as the flow connection to the first outlet duct 30 of the injection housing 1. The flow connection to the suction source may be implemented, for example, as shown in the left part of FIG.

According to another embodiment, the flow connection through the duct 41 to the suction source may be effected as shown in the right part of Figure 3 along a by-pass path of the outlet chamber 31. In this case, the flow connection may be formed to the same or different suction source with which the spraying chamber 5 is known to drain the detergent mixture 3, 7. The flow connection may be formed to an external outlet channel 32. For example, a suction blower is suitable.

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In some embodiments, the second outlet duct 40 extends to the side of the drain 24 so that the inlet opening of the second outlet duct 40 is disposed between the web W and the press member 21 (viewed perpendicular to the plane formed by the web assuming a simplified web 10).

According to some embodiments, the second outlet duct 40 extends to the side of the sink 24 so that the suction opening of the second outlet duct 40 is arranged laterally between the edge W 'of the web W and the end 21' of the press member 21. 15

According to some particularly preferred embodiments, the second outlet duct 40 extends to the side of the throat 24 so that the inlet opening of the second outlet duct 40 is arranged laterally to the level or outside of the end 21 'or edge of the press member 21. The gap 20 42 between the end 21 'of the press roll 21 and the second outlet passage 40 can then be narrowed or sealed (for example by means of dragging gaskets) to reduce flow loss and leakage of the injection casing.

Implemented on the side of the throat 24, the targeted removal of the treating agent mixture 3, 7 can effectively reduce the overpressure 25 causing leakage from the injection casing by removing from a high pressure zone with high flow velocities and laterally oriented in the discharge direction.

Fig. 4 is a side elevational view of a fibrous web coating device 101 for drawing air 3 from the sides 30 of a sink 26 formed between the web W and the counter roll 51 through third outlet passages 50. The counter roll 51 is arranged as a track support member against which the track rests and maintains track tension. The purpose of the counter roll 51 is to maintain the track W at a suitable constant distance from the coating applicator means 52 such as spray or jet nozzles. The scraper 53 is adapted to scrape the web in the direction of travel of the web after the application means 52. The scraper 53 presses the web against the counter roll 51 and smoothes the coating layer. The path of the web following the scraper 53 is not shown in Figure 4, but the web may be deflected from the coating device 101 after the scraper 53.

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It has been found that, especially at high travel speeds, the air 3 carried by the track W and the surface of the counter roll 51 forms an overpressure zone in the throat 26 formed between the track and the track supporting roll. A third outlet channel 50 is provided on each side of the throat 26 to reduce air passage from the pressurized throat from zone 26 between the counter roll 51 and track W 10 and to reduce bagging on at least one side of the throat 26. Preferably, both sides of the throat 26 have a third outlet 3, since the removal takes place in the high pressure zone, where the flow rates 15 are high and are oriented sideways in the discharge direction, as shown in connection with Figure 3. In adapting the third outlet channel 50 to the end of the counter roll 51, the principles set forth in the description of Figures 1-3 in connection with the second outlet channel 40 may be utilized mutatis mutandis.

The foregoing description provides non-limiting examples of some embodiments of the invention. However, it will be apparent to one skilled in the art that the invention is not limited to the details set forth, but that the invention may be practiced in other equivalent ways.

Some features of the embodiments shown may be utilized without the use of other features. The foregoing description is to be construed as merely describing the principles of the invention and not limiting the invention. Thus, the scope of the invention is limited only by the appended claims.

Claims (15)

Apparatus for treating a fibrous web (W), said device comprising at least one supporting member (21, 22; 51) supporting the fibrous web (W) and comprising a movable surface adapted to the fibrous web, and in use the supporting member and the fibrous web are adapted to forming between them a throat (24, 24 '; 26), characterized in that a removal tool (40, 40'; 50) for a flow (3, 7) is adapted at the connection of at least one end of the throat (24, 24); '; 26). Device according to claim 1, characterized in that the removal tools (40, 40 '; 50) comprise at least one of the following: a second removal channel (40), a common removal channel (40') and a third removal channel (50). Device according to claim 1 or 2, characterized in that the removal of flow (3, 7) is adapted to take place at the level or outside the level of the end of the support member (21, 22; 51). Device according to claim 1 or 2, characterized in that the removal of flow (3, 7) is adapted to take place in the region between the end of the support member (21, 22; 51) and the channel of the web (W). Device according to claim 1 or 2, characterized in that the removal of flow (3, 7) is adapted to take place between the support means (21, 22; 51) and the edge of the web (W). Device according to any of claims 1-5, characterized in that the device comprises at least one spray chamber (5, 5 '), and the support means (21, 22) comprises a pressure roller or pressure band or a corresponding pressure means adapted as part of the spray chamber. , and the flow (3, 7) comprises an air and treatment blend. Device according to any one of claims 1-6, characterized in that for each throat (24, 24 ') located in the spray chamber (5, 5'), at least one removal tool (40, 40 ') is provided for removing the air. and treatment compound (3, 7). 8. Apparatus according to claim 7, characterized in that a common removal tool (40 ') is provided for two adjacent rods (24, 24'). Device according to any one of claims 1-8, characterized in that the removal tools (40, 40 '; 50) comprise a channel (41) for forming a flow connection with a suction source of a removal source. 10. Device according to claims 6 and 9, characterized in that the spray chamber (5, 5 ') comprises a first removal channel (30) extending to a transverse length of the spray chamber, and the channel (41) is adapted for flow communication with the suction source of the spray chamber. first removal channel. Device according to any of claims 1-5, characterized in that a counter roll (51) is adapted as a support member and the flow (3) comprises air. 20 A method of treating a fibrous web (W), wherein: - a movable fibrous web (W) is supported by at least one support member (21, 22; 51) comprising a movable surface adapted to the fibrous web, and - a throat (24, 24). 26; is formed between the support member and the fiber web, characterized in that in the process: 25. a flow (3, 7) is removed with a removal tool (40, 40 '; 50) at the connection of the at least one end of the throat (24, 24). '; 26). 13. A method according to claim 12, characterized in that overpressure in the throat (24, 24 '; 26) is lowered to remove the lateral flow from the throat. 30 Method according to claim 12 or 13, characterized in that the air and treatment blend (3, 7) is removed from a spray chamber (5.5 ') in the throat (24, 24') between the web (W) and a pressure means (21). , 22) adapted as a support body. 15. A method according to claim 12 or 13, characterized in that air (3) is removed from the throat (26) between the web (W) and a counter roll (51) adapted as a support member.