EP1586701A1 - Drying arrangement - Google Patents

Abstract

A papermaking assembly has a drying station (1) with a heated dying cylinder (3) in contact with the paper web (2). A pressure hood (4) is applied to the cylinder. The paper runs through the gap between the cylinder and pressure hood in contact with a single water take-up closed loop belt (5). The closed loop belt has an impermeable outer face in contact with the pressure hood, and a single or double moisture-permeable layer in contact with the paper. The moisture permeable layer is a felt fleece or woven fabric. The fleece or woven layers are joined by needle action, bonding or welding. The impermeable layer is metal foil, thin sheet metal or plastic.

Description

The invention relates to a drying arrangement with a heated drying cylinder for dewatering a paper, board, tissue or other fibrous web in a machine for producing and / or finishing the fibrous web, above of which a pressure is applied to the drying cylinder applying means, wherein the fibrous web between the drying cylinder and the means is guided.

EP 0 949 377 A2 discloses a drying arrangement for continuous drying a porous web known. The drying arrangement comprises a drying cylinder, which is wrapped by the web over at least two thirds of its lateral surface. On top of the drying cylinder are next to nozzles for applying a Coolant arranged a plurality of rotating rollers, which in their interior one each hydraulic unit for applying a contact pressure against the Have drying cylinder.

In DE 35 32 853 C2 discloses a method and an apparatus for drying a fibrous web of paper, cardboard or the like described. The Fibrous web becomes, while at a water and water vapor receiving intermediate band, before reaching a drying area of a Subjected to deaeration treatment. The intermediate band will be in one Drying area led around the drying cylinder. The fibrous web becomes covered by a metal band during its rotation around the drying cylinder. The Metal strip becomes after leaving the drying cylinder in a return loop returned to the drying area. The intermediate band will after the Leaving the drying cylinder freed of condensed water. The Fibrous web is between the intermediate band and the metal band around the Drying cylinder led while it is cooled. The warming of the Metal strip takes place in the return loop, and the heated metal strip is heated the outside of the circulating around the drying cylinder web in direct contact.

Furthermore, arrangements are possible in which between a heated Drying cylinder and arranged above the drying cylinder pressure hood a fibrous web together with two sieves and a water-impermeable one Tape is passed. There is the fibrous web as a result of heating through the heated drying cylinder moisture from the sieves, which in turn over Cool the impermeable tape so that the moisture in them condensed. Each of the two screens must as well as the impermeable band after exiting the area of the hood covered by the pressure hood Drying cylinder individually via a plurality of guide rollers to the entry point the fibrous web in the area between the pressure hood and the Drying cylinders are returned.

From WO 98/42913 a method and a dry arrangement are known in which a fibrous web to be dried horizontally between two belts is passed. The lower band is passed through a chamber filled with water cooled while the upper band is heated by a pressure chamber. Between the upper band and the fibrous web a felt belt is guided, to which the Fibrous web gives off its moisture.

It is the object of the invention, the structure of the aforementioned Dry arrangement simplify.

This object is achieved in a dry arrangement of the above mentioned type solved in that together with the fibrous web a single, the moisture from the fibrous web absorbing or receiving Covering between the drying cylinder and the means can be passed. The Means is in particular a pressure hood.

According to the invention, the number of guide or guide rollers is reduced and the Screen guide simplified. This will reduce the cost of producing the Dry arrangement lowered, but also reduces downtime and the Energy consumption reduced. According to the invention, the properties of the two previously used screens combined in a single screen.

Advantageous developments of the invention will become apparent from the dependent claims, the description and the drawing.

As advantageous proves to be a dry arrangement in which the absorbent or receiving covering and one absorbing or receiving Covering against the means sealing fabric in a single band summarized and integrated. The band has at least one Moisture-storing layer and an impermeable layer. Through this simple and compact design rollers for the deflection of two individual Ribbons from the exit of the fibrous web from the area between the Drying cylinder and the pressure hood to the inlet of the fibrous web in the Saved area between the drying cylinder and the hood.

The band preferably consists of a plurality of layers, each fulfill different functions. One of the fibrous web facing Outer layer should either have a high capillarity to get as fast as possible Absorbing moisture from the fibrous web, or the layer has a possible fine surface texture to prevent the appearance of marks on the surface To avoid fibrous web during contact with the outer layer. On the Outside layer follows within the band, a first storage layer, the for example via a narrow binding layer with a second storage layer connected to store the water taken up from the fibrous web. The second storage layer is followed by an impermeable layer which forms the Tape seals against the pressure hood.

In an advantageous embodiment of the invention it is provided that the Cover the surface of a felt fleece or fleece or fabric layer on the side facing the fibrous web and that they have a having water-absorbing or water-absorbing tissue. This unites the Covering the properties of a fine mesh screen, as it stands the technique is used adjacent to the surface of the fibrous web, and the properties of a coarse sieve that absorbs the fibrous web discharged moisture is used. The nonwoven layer is for example as a random web or designed as oriented fleece.

Through the felt fleece or the fabric markings can be on the Wholly or at least substantially avoid fibrous web while the sieve have sufficient storage capacity for that through the hood or Press shoes from the fibrous web pressed out water has. The felt or Tissue layer or fleece overlay of the covering takes over the transmission of the perpendicular to the felt plane acting compressive force, while the single or multi-layered Basic fabric of the felt the forces acting in the felt plane, especially the Pulling forces, absorbs. Other functions of the felt layer consist in the storage the absorbed moisture and in a wear protection.

Preferably, the covering consists of at least two permanently together bonded felt fleece or nonwoven or fabric layers, which are also in Insert combination with a mesh. The single ones Stringing or clothing layers are inseparable connected. Also, a plurality of mesh fabrics can be used. A inseparable connection of two meshes comes for example by needling by needling together with a fleece.

The felt fleece or fleece or fabric layers are preferably through Needling, gluing or joined together by welding. additionally The covering can also be layers of a plastic or a Metal mesh, a plastic or metal foil or a thin sheet metal include by gluing or welding with the at least two felt fleeces or fleece or Tissue layers are connected.

The individual meshes preferably differ in their capillarity. The the fibrous web facing side has the function to support the fibrous web. The side facing away from the fibrous web side has the task of the Fibrous web moisture absorbed as condensate and tie to save until the fibrous web removed from the fabric again becomes. As long as the fibrous web is brought into contact with the fabric is the condensed water in particular by the centrifugal force or by Capillary forces prevented from flowing back into the fibrous web.

The capillarity of the fabric is on the side facing the fibrous web advantageously chosen lower than on the side facing away from the fibrous web Page. For this purpose, the covering on the side facing the fibrous web coarser fibers than on the other side, on which the recorded Moisture is stored.

When a barely marks on the fibrous web leaving surface of the Covering is required, an additional thin layer of fine fleece or can be Use fabric fibers, which have a fiber weight between 1 and 140 dtex exhibit. Also fiber weights up to 200 or 300 dtex are possible. Prefers However, a fiber weight is 140 dtex. (The unit "dtex" gives the fiber weight in grams per 10,000 m fiber length.) The capillarity of the felt layers can be achieved among other things by the thickness of the non-woven or fabric-forming fibers and by set their material targeted.

Also, the choice of the thickness of the non-woven or fabric-forming fibers and their material the capillarity of the felt layers can be adjusted. Advantageously, for the Covering, in particular on the side facing the fibrous web, a Mixture of fibers of different thickness and / or different Materials used, in particular made of a plastic, carbon or Glass fibers, or from a natural material, in particular wool or silk.

It also proves to be advantageous to rewet the fibrous web through To obstruct the condensation absorbed by the clothing by the Covering on the fibrous web facing side of a nonwoven with a hydrophobic material.

Likewise, it can additionally be provided that the capillarity of the clothing by a mechanical treatment, by a thermal treatment, in particular the melting of admixed melt bodies, for example in Fiber shape, or by a chemical treatment, especially the subsequent Introduction of chemical materials, in particular of synthetic resins, lacquers or Finishes, is affected. Also, it is possible to do several of these procedures simultaneously or in succession.

A membrane can also be used in conjunction with the sieve or the felt fleece or the fabric layer can be provided.

The covering comprises at least one with the at least two felt fleeces or Nonwoven or fabric layers needled screen fabric or scrim that has an in Machine direction oriented non-woven material forms. Can be used here also come plastic and metal mesh. Alternatively, a Plastic film or a metal foil or a thin sheet can be used.

To seal against the pressure hood, the drying cylinder on his Covered surface, or against any other pressure on the Drying cylinder performing means is the covering with a r impermeable n, in particular by impregnation with a resin, an elastomer, a Thermoplastic, a silicone rubber, a paint or the like incurred Layer or provided with a plastic layer, in particular of polyurethane, consists. The coating preferably has a smooth surface that it seals against the wall of the agent. As opaque or impermeable However, layer also allows a metal layer to be used, which is welded together by welding, Gluing u. Like. Connected to the underlying screen or storage layer.

An advantage is a water-impermeable paint coating, which is a smooth, has sealing surface against the wall of the pressure hood.

The invention also relates to a drying arrangement, in particular in one the embodiments described above, which is characterized in that a the moisture of the fibrous web receiving, at least one absorbent or receiving layer and the at least one layer opposite to the Middle sealing layer comprising band at the outlet side of the fibrous web via at least one arrangement for dispensing the of the fibrous web absorbed moisture is conducted. Both are particularly suitable for this purpose Suction rolls as suction boxes, so that the arrangement at least one suction roll and / or a suction box. It is understood that instead of Deflection rollers or guide rollers around which the band is guided, respectively Suction rollers, in particular in conjunction with suction boxes, are used can.

If a suction roll is used, that is at least one suction roll preferably an outlet-side wedge with a between the band and the Suction roller downstream of a vacuum chamber forming lamella. In the Vacuum space is combined with ambient air also moisture from the Woven fibrous web sucked over that in the suction roll Vacuum chamber is removed.

If a suction box is used, this advantageously has an inlet and a on the outlet side of the absorbing layer of the tape touching bar. The bar can have different shapes; For example, she may be in the tape adjacent area may be tapered or rectangular in cross-section or have a semicircular cross-section.

Fig. 1

einen Querschnitt durch eine Trockenanordnung, in der ein Siebband und ein undurchlässiges Band 6 getrennt voneinander zusammen mit der Faserstoffbahn 2 zwischen dem Trockenzylinder 3 und einer Druckhaube 4 hindurchgeführt werden,

Fig. 2

den Aufbau eines Bandes 15 mit mehreren Siebschichten 16, 17, 18, 19 und mit einer undurchlässigen Schicht 20 in der Schnittansicht zusammen mit einer Darstellung des Verlaufs der Kapillarität über der Dicke des Bandes 15,

Fig. 3

einen Querschnitt durch eine weitere Trockenanordnung, in der ein mindestens eine Siebschicht und eine undurchlässige Schicht umfassendes Band 15 eingesetzt wird,

Fig. 4

einen Keil 28 am Auslauf einer Siebsaugwalze 24 in einer Detailansicht und

Fig. 5 - 8

Siebsaugkästen 35 in verschiedenen Ausgestaltungen.

The invention will be explained in more detail in exemplary embodiments. In the drawings show:

Fig. 1

a cross section through a drying arrangement in which a screen belt and an impermeable belt 6 are separated from each other together with the fibrous web 2 between the drying cylinder 3 and a pressure hood 4,

Fig. 2

the structure of a band 15 having a plurality of screen layers 16, 17, 18, 19 and with an impermeable layer 20 in the sectional view, together with a representation of the course of the capillarity over the thickness of the band 15,

Fig. 3

3 shows a cross section through a further drying arrangement in which a band 15 comprising at least one screening layer and an impermeable layer is used,

Fig. 4

a wedge 28 at the outlet of a Siebsaugwalze 24 in a detailed view and

Fig. 5-8

Siebsaugkästen 35 in various configurations.

A drying assembly 1 (Fig. 1) in a machine for manufacturing a Fibrous web 2 comprises a heated drying cylinder 3, which on its Top is surrounded by a pressure hood 4, in which a cooling medium flows to the heat of a circulating around the drying cylinder 3 Covering 5 absorb moisture absorbed from the fibrous web 2.

Instead of the pressure hood 4, other units above the Drying cylinder 3 may be arranged, for example, rollers or press shoes, in Connection with the heated drying cylinder 3 and the fabric 5 serve To remove the fibrous web 2 moisture. Also in the rollers or the Press shoes can be cooling units, for example from a medium flowed through cooling channels, be present.

The fibrous web 2 is together with the fabric 5 over the Drying cylinder 3 out. In addition, a likewise carried impermeable Band 6 present, which runs between the fabric 5 and the pressure hood 4.

Below the drying cylinder 3 are each at the same distance to perpendicular central axis A of the drying cylinder 3 two support rollers 7, 8 attached, the drying cylinder 3 in the direction of arrows B, C against in the direction of Support arrow D acting weight of the pressure hood 4. The support rollers 7, 8 also have a guide function for the fibrous web 2, the fabric 5 and the band 6, by being passed around the support rollers 7, 8, whereby also the area of action of the drying cylinder 3 on the fibrous web 2 increases and thereby the efficiency of the drying process is improved.

The fabric 5 is about deflection rollers 9 to 14 to the drying cylinder 3 and led the pressure hood 4 around. Likewise, for the band 6, if its Function not integrated in the fabric 5, separate (not shown here) Deflection rollers required. The fabric 5 is in (also not shown) Suction or pressing devices taken from her from the fibrous web 2 Moisture removed again.

A band 15 (Figure 2) comprises an outer layer 16 which, while the fibrous web 2 is guided over the drying cylinder 3, is in direct contact with this and deprives her of moisture. Within the band 15 this is then on Memory layers 17 and 18 forwarded via a bonding layer 19th connected to each other. Opposite the pressure hood 4, the band 15 through an impermeable layer 20 sealed. The bonding layer 19 can be omitted, if the storage layers 17, 18 directly because of their surface texture or can be connected together by means of an adhesive.

Depending on the desired properties of the fibrous web 2 can be use different materials for the layer structure of the band 15.

As a rule, a high capillarity K in the outer layer 16 is desired. In In this case, a course of capillarity K over the thickness of the band 15th used as represented by the curves 21, 22. It turns out that in As a rule, the capillarity K is higher, the coarser the tissue or the structure the respective layer is. In the case of the outer layer 16, this means that Markings on the fibrous web 2 must be accepted if a high capillarity K is desired.

On the other hand, if marks on the fibrous web 2 are avoided must, accepted that an outer layer 16 of a fine-meshed Tissue has a lower capillarity K, so that in this case the course of Capillarity K is represented by a curve 23, wherein in the case of the curves 21, 22, 23 and the courses of the capillarity K in the other layers 17 to 18 can be customized by choosing different materials. The Layer 17 should, so that in it the moisture is stored as well as possible and not back into the outer layer 16 flows, preferably a lower capillarity K than the Outer layer 16 have.

The band 15 (Figure 3) can be replaced by the string 5 and the impermeable band Insert band 6 (see Fig. 1). It is like the fabric 5 via guide rollers. 9 led to 12 For drainage serve in the case of the band 15, for example Suction rollers 24, 25, each having a stationary suction zone 26 and 27 respectively. to better suction of moisture are at the outlets of the suction rolls 24, 25th each wedges 28, 29 arranged.

These are constructed in detail, as shown in Fig. 4 on the basis of the wedge 28. The wedge 28 has one in the gusset between the shell wall of the suction roll 24 and the band 15 tapered body 30, above which a Slit 31 is sucked in the direction of an arrow E air in a cavity 32, the at the same moisture from the water-containing layers of the tape 15th entraining. This mixture of water and air is then through holes 33 in the Mantle wall of the suction roller 24 sucked in the suction zone 26 in this and derived from there. To form the cavity 32, the wedge 28 has at its front end a lamellar thickening 34, which attached to the body 30 is.

Instead of using the suction rolls 24, 25 or in addition to them can be also use at least one suction box 35 (Fig. 5) to remove the moisture from the Layer sequence 16, 17, 19, 18 of the strip 15 to withdraw. The suction box 35 has inside a negative pressure chamber 36. Adjacent to the band 15 the suction box 35 in each case via an inlet or outlet side the absorbent or receiving outer layer 16 of the band 15 touching bar 37, 38 or a Sidewall on. Also in the construction of the suction box 35 is in the direction of Arrows F, G sucked in a mixture of water and air, which subsequently from the Chamber 36 is discharged.

In a further alternative, the strips have 37, 38 or side walls in the Area in which they adjoin the band 15, semi-circular terminations 39, 40th (Figure 6). In a further alternative, rib-shaped strips 41, 42 may also be used (Figure 7). To ensure sufficient stability can provide support ribs 43, which have the same width as the strips 37, 38th or side walls. In another embodiment, on the strips 37, 38 narrow strips 44, 45 (FIG. 8) with a rectangular cross-section.

Claims (19)

Dry arrangement (1) with a heated drying cylinder (3) for dewatering a paper, cardboard, tissue or another fibrous web (2), above which a pressure on the drying cylinder (3) performing means (4), is arranged the fibrous web (2) can be guided between the drying cylinder (3) and the means (4),
characterized in that together with the fibrous web (2), a single, the moisture from the fibrous web (2) absorbing or receiving fabric (5) between the drying cylinder (3) and the means (4) can be passed. Dry arrangement (1) according to claim 1,
characterized in that the absorbing or absorbing clothing (16-19) and a clothing (20-19) which absorbs or absorbs the clothing (16-19) in relation to the means (4) are combined in a single band (15) comprising at least one the moisture-storing layer (17, 18) and an impermeable layer (20). Dry arrangement (1) according to claim 1 or 2,
characterized in that the fabric (5) has the surface of a felt fleece or a fleece or a fabric layer on the side facing the fibrous web (2) and that it has a water-absorbent fabric. Dry arrangement (1) according to one of claims 1 to 3,
characterized in that the covering (5) consists of at least two permanently bonded felt fleeces or fleece or fabric layers. Dry arrangement (1) according to claim 4,
characterized in that the felt fleeces or the fleece or fabric layers are joined together by needling, gluing or welding. Dry arrangement (1) according to one of claims 1 to 5,
characterized in that the covering (5) comprises a metal or a plastic fabric, a plastic or metal foil or a thin sheet, which are in particular connected by gluing or welding with the at least two felt fleeces or fleece or fabric layers. Dry arrangement (1) according to one of claims 1 to 6,
characterized in that the capillarity of the fabric (5) on the fibrous web (2) facing side is less than on the side facing away from the fibrous web (2). Dry arrangement (1) according to one of claims 1 to 7,
characterized in that the fabric (5) on the fibrous web (2) facing side has a thin layer of fine nonwoven or fabric fibers, in particular with a fiber weight between 1 and 300 dtex, preferably with a fiber weight of 140 dtex. Dry arrangement (1) according to one of claims 1 to 8,
characterized in that the covering (5), in particular on the side of the fibrous web (2) side, of a mixture of fibers of different thickness and / or of different materials, in particular of a plastic, carbon or glass fibers, or of a natural material , in particular of wool or silk. Dry arrangement (1) according to one of claims 1 to 9,
characterized
the covering on the side facing the fibrous web (2) consists of a hydrophobic material. Dry arrangement (1) according to one of claims 1 to 10,
characterized in that the capillarity of the fabric (5) by a mechanical treatment, by a thermal treatment, in particular the melting of admixed fused bodies, for example in fiber form, or by a chemical treatment, in particular the subsequent introduction of chemical materials, in particular of synthetic resins, paints or seasonings is affected. Dry arrangement (1) according to one of claims 1 to 11,
characterized in that the covering (5) comprises at least one needled with the at least two felt fleeces or fleece or fabric layers screen cloth or scrim. Dry arrangement (1) according to one of claims 1 to 12,
characterized in that the covering (5) by an impermeable, in particular by impregnation with a resin, an elastomer, a thermoplastic, a silicone rubber, a varnish or the like resulting layer or by a plastic layer, in particular of polyurethane, or by a metal layer relative to the Pressure on the drying cylinder (3) applying means (4) is sealed and has a smooth against the wall of the means (4) sealing surface. Dry arrangement (1) according to one of claims 1 to 13,
characterized in that the covering (15) has an outer layer (16) facing the fibrous web (2), an impermeable coating (20) facing the means and at least two storage layers (17, 17) arranged between the outer layer (16) and the coating (20). 18). Dry arrangement (1) with a heated drying cylinder (3) for heating a paper, cardboard, tissue or another fibrous web (2), above which a pressure on the drying cylinder (3) performing means (4), is arranged the fibrous web (2) can be passed between the drying cylinder (3) and the means (4), in particular according to one of claims 1 to 14,
characterized in that a band (15) which absorbs the moisture of the fibrous web (2), at least one absorbent or receiving layer (17, 18) and a layer (20) covering the at least one layer with respect to the middle sealing layer (15) is provided on the outlet side of the fibrous web ( 2) via at least one arrangement (24, 25, 35) for delivering the moisture from the fibrous web (2) recorded. Dry arrangement (1) according to claim 15,
characterized in that the arrangement comprises at least one suction roll (24, 25) and / or a suction box (35). Dry arrangement (1) according to claim 16,
characterized in that the at least one suction roll (24, 25) is arranged downstream of a run-out wedge (28, 29) with a between the belt (15) and the suction roll (24, 25) forming a vacuum space blade (34). Dry arrangement (1) according to claim 16,
characterized in that the suction box (35) has an inlet and a discharge side of the absorbent layer of the strip touching strip (37, 38) or side wall. Dry arrangement (1) according to claim 18,
characterized in that the strips (37, 38) in the area adjacent to the strip (15) are tapered in the shape of a ridge or have a rectangular cross section or have a narrow web or a semicircular cross section.

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