EP0608533B1 - Process and apparatus for dewatering a web with presses - Google Patents

Abstract

Wet-press arrangement, in which the flexible press cover (18) of a shoe-press roll (7) picks up the web (2) to be dewatered at a first press point (5), directly from the wire (1) on which the web has been formed. The web then runs together with the press cover (18) through a second press point (8) which is designed as a felted and extended press nip. Thereafter, the web runs through a third press point (14), where it is transferred from the smooth envelope surface of the press cover (18) onto the smooth envelope surface of a press roll (15). The web then runs with the latter through a fourth press point (24), which is again designed as a felted and extended press nip. After this, the web (2) still follows the press roll (15) as far as a pick-up point. <IMAGE>

Description

The invention relates to a method and a device for dewatering a fibrous web formed by means of one or more endless sieve belts, in particular in a paper production machine, through which the web is guided in a (usually) horizontal machine running direction according to the preamble of claims 1, 2 and 4 and 5.

In general, dewatering is carried out by passing the web successively through a plurality of press stations, an endless and water-absorbing porous press belt running through at least one of these press stations, preferably a so-called "felt belt" or "wet felt". The web is guided from press to press in such a way that it never has to run freely, so that it is always supported by a wire belt or by a felt belt or by the outer surface of a roller.

D1:

US 4,285,766

D2:

DE 273783, Figur 2

D3:

DE 3425077 = US 4,662,992

D4:

DE 3808293 = US 4,923,570

D5:

US 4,556,451

D6:

DE 4026021 (Fig. 3) = US 5,178,732

State of the art literature:

D1:

US 4,285,766

D2:

DE 273783, Figure 2

D3:

DE 3425077 = US 4,662,992

D4:

DE 3808293 = US 4,923,570

D5:

US 4,556,451

D6:

DE 4026021 (Fig. 3) = US 5,178,732

In many modern papermaking machines, the web is dewatered using the method described in D1 or a similar method. Thereafter, the web is first passed between the screen belt on which the web is formed and a first felt belt supported by a take-off suction roll through a first press point, after which the web with the first Felt belt continues. The first felt belt, supported by a suction press roll, then guides the web through two further press stations, after which it is passed through the smooth outer surface of a press roll through at least one further press station. This well-known method has become proven. However, the large space requirements and the high costs for the acquisition and operation of such a press section are disadvantageous, particularly with regard to the suction rolls.

According to another proposal described in D2 and originating from the early days of mechanical paper production, the paper web is transferred from the screen belt to the smooth outer surface of a first press roller in the first press point and then guided by this through further press points, namely through two felted and one without felting Pressing point. After the latter, the web is guided into a last felted press point by means of a further smooth press roll. The arrangement is such that the web passes the last press point counter to the machine direction and must therefore first be continued behind this press point using the last felt belt. As a result, rewetting of the web from this felt band (and thus a web dry content that is inadequate in practice) is to be expected. The very large diameter of the first press roll relative to the diameter of the other press rolls is also unfavorable. For this and other reasons, the known device is not suitable for use in modern papermaking machines.

According to D3, the web is again removed from a screen belt by means of a smooth press roll and passed through a felted press station. This is designed as an extended and felted press nip in the web running direction by using a so-called shoe press roll, which has a flexible circumferential press jacket and a press shoe. The press jacket comes into contact with the felt belt in the press nip. Another fundamental difference between D2 and D3 is that the screen belt touches the underside of the web before and in the first press point in D2 (as is usually the case), in D3 in contrast, the top of the web. In D3, the web is formed in a twin-wire zone, behind which the web continues with the top wire in the upward direction. A steam blower box and suction boxes are provided in front of the first press point for draining the web. This results in the disadvantage that the press rolls have to be arranged at a relatively great height above the twin-wire zone and above the subsequent dryer section. The known device is therefore not highly recommended, partly because of the need for expensive and high-quality frames (with the risk of mechanical vibrations), partly because of the hot air rising from the inlet into the dryer section and also because of all of these circumstances, making it difficult to operate and access during operation and from time to time the necessary work to replace rollers, sieve and felt belts. Another disadvantage of the method described in D3 is that the web is drained only on one side. This results in the danger that the finished paper web has unequal properties on both sides (two-sidedness of the paper web). It is also unfavorable for the web to be guided through the subsequent dryer section, namely in such a way that (according to FIGS. 1 and 3) the top of the web comes into contact with the drying cylinders below; this makes it considerably more difficult to remove any waste paper.

Various wet press arrangements are described in D4 with a shoe press roll, the flexible circumferential press jacket of which has a smooth outer jacket surface which comes into direct contact with the paper web. A radially movable press shoe (and a concave sliding surface) is supported on a stationary support body (or several press shoes of this type). In addition, rigid strips with a convex sliding surface are provided.

The wet press arrangement described in D5 includes i.a. three press points arranged one behind the other, namely one with felt, one with no felt and one with last felt. However, there is no shoe press unit, i.e. all press rolls are normal pipe rolls (therefore insufficient drainage capacity).

In Fig. 3 of the D6, two shoe press rolls together form the felt-free press nip. With some types of paper, it is difficult to ensure that the paper web is safely changed from one press jacket to another.

• a) Durch das Pressen soll ein möglichst hoher Bahn-Trockengehalt erzielt werden, u.a. dadurch, daß wenigstens eine an sich bekannte Schuhpreßwalze anwendbar ist.
• b) Die fertige Papierbahn soll auf ihren beiden Seiten möglichst weitgehend gleiche Eigenschaften aufweisen. Insbesondere soll der Unterschied zwischen den Rauhigkeitswerten der beiden Bahnseiten möglichst gering sein (geringe topographische Zweiseitigkeit). Wichtig ist in vielen Fällen auch, daß Porosität und Saugfähigkeit auf beiden Seiten der Papierbahn möglichst gleich sind (geringe strukturelle Zweiseitigkeit).
• c) Die Bahn soll derart geführt werden, daß sie zwischen den Preßstellen stets durch irgendein Bahnführungselement gestützt ist, um Bahn-Abrisse möglichst zu vermeiden. Außerdem soll sie derart in die nachfolgende Trockenpartie geführt werden, daß zumindest am ersten Trockenzylinder die Bahnunterseite mit der Zylindermantelfläche in Kontakt kommt.
• d) Der Platzbedarf für die Vorrichtung, also für die Pressenpartie, soll möglichst gering sein, sowohl in horizontaler Richtung (Maschinenrichtung) als auch in vertikaler Richtung (möglichst geringe Bauhöhe). Hierdurch soll eine möglichst gute Bedienbarkeit erzielt werden, also möglichst weitgehend vom Maschinenboden aus.
• e) Die Kosten für Anschaffung und Betrieb sollen möglichst gering sein, also möglichst weitgehende Vermeidung teurer Walzen, z.B. Saugwalzen mit ihrem relativ hohen Energieverbrauch für Antrieb und Unterdruck-Erzeugung.

The present invention is based on the object of specifying a method and a device according to which as many of the following requirements as possible can be met when the web is dewatered:

• a) The highest possible dry web content is to be achieved by the pressing, inter alia in that at least one shoe press roll known per se can be used.
• b) The finished paper web should have largely the same properties on both sides. In particular, the difference between the roughness values of the two web sides should be as small as possible (low topographic two-sidedness). In many cases it is also important that the porosity and absorbency are as equal as possible on both sides of the paper web (low structural two-sidedness).
• c) The web should be guided in such a way that it is always supported by some web guiding element between the pressing points in order to avoid web breaks as far as possible. In addition, it should be guided into the following dryer section in such a way that the underside of the web comes into contact with the cylinder jacket surface at least on the first drying cylinder.
• d) The space required for the device, that is to say for the press section, should be as small as possible, both in the horizontal direction (machine direction) and in the vertical direction (construction height as low as possible). As a result, the best possible usability is to be achieved, that is to say as far as possible from the machine floor.
• e) The costs for acquisition and operation should be as low as possible, ie avoiding expensive rollers as much as possible, for example suction rollers with their relatively high energy consumption for drive and vacuum generation.

To achieve this object, several combinations of partially known method steps or device features are provided according to the invention. Different combinations of method steps are specified in independent claims 1 and 2 and two correspondingly different devices in independent claims 4 and 5. All of these claims leave it open whether the belt, e.g. Screen belt, touches the bottom or top of the web when the web is brought up to the first press point.

All solutions have in common that the web is removed from the belt (screen belt or felt belt) directly through the smooth jacket surface of a first press roll. If this web take-off takes place directly from the screen belt, then there is no need for a take-off suction roll including a vacuum blower. Nevertheless, the take-off point forms a first press point, which can be used in numerous variants of the invention to drain the web. It is also common that this first press point is followed by a felted and (in most exemplary embodiments) designed as an extended press nip (and thus having a high drainage capacity) second press point. So there is no need for an expensive suction press roll. Furthermore, a third and provided for smoothing the web (and therefore formed by two smooth outer surfaces) press point; or it is ensured by the web guide according to the invention that the space required for such a third press point is available in any case. This ensures the required uniformity of surface quality on both sides of the web.

The combinations of features of claims 1 and 4 have the following additional advantages compared to D2: Lower construction costs, since the required drainage capacity is generally achieved with a smaller number of pressing points. Avoiding rewetting of the web behind the last (felted) press nip through more favorable web guidance, i.e. in that the web runs essentially in the machine direction through the last nip; thus the felt can be separated from the web directly behind the press nip.

The combinations of features of claims 2 and 5 provide that the web comes into direct contact with the flexible press jacket of at least one shoe press roll. This results in the advantage of particularly high dewatering performance of the felted press point in question, because a normal press roll with relatively large recesses for transporting water can be arranged here within the felt loop. In contrast, in other designs of the invention, a shoe press roll with a relatively thin, flexible press jacket is arranged in the felt loop, which can only be provided with rather small recesses for transporting water.

Claims 2 and 3 and claim 5 relate to an important further aspect of the invention. Thereafter, in many designs of the invention, a pair of press rolls available, which forms a felt-free press point (ie between two smooth outer surfaces, both of which come into direct contact with the web), one of the two press rolls being a "normal pipe roll" and the other a "shoe press roll". The latter has a bar that presses the tubular press jacket against the normal pipe roller. The bar is radially displaceable relative to the stationary support body of the shoe press roll in order to be able to open and close the press point and to be able to vary the press force (if necessary during operation). Both press rolls can thus be rigidly supported on the foundation or frame. Overall, an extremely simple yet variable arrangement is thus achieved. The width of the press nip can be determined by the shape of the sliding surface of the bar, namely convex, flat or concave.

Due to these advantages, this pair of feltless press rolls is clearly superior to a pair of rolls consisting of two normal tube rolls (known e.g. from D2 or D5).

The order of the two press rolls (i.e. whether the web changes from the shoe press roll to the normal raw roll or vice versa) can be chosen arbitrarily. However, the first-mentioned variant is preferred because the lateral surface of the second roller generally has to be harder than that of the first roller and because the flexible jacket of the shoe press roller cannot be as hard as desired; on the other hand, the roll cover of the normal tube roll can be made with any hardness.

The press roll pair described is - for the reasons explained above - also superior to a roll pair formed from two shoe press rolls (known from D6); because it is difficult (if at all possible) to produce two flexible press sleeves with sufficient surface hardness values.

According to the invention, the pair of press rolls is combined with other press rolls, in particular in order to form press nips which are used for intensive dewatering of the web. Therefore, the shoe press roll, as known per se, has at least one radially movable and concave press shoe, which forms a felted, extended press nip with another press roll. In addition, the tube roller, together with an additional press roller (preferably a shoe press roller), can form a further felted (preferably extended) press nip. This gives you an extraordinarily compact press section with two felted dewatering press stations of high capacity.

If the belt leading the web, e.g. The belt that touches the top of the web has the following additional advantages compared to D3: the press rolls are at about the same height as the preceding section of the screen and the dryer section below; thus high-quality and vibration-prone frames are avoided; the machine is also easier to operate, namely at least predominantly from the machine floor. It is also possible that in the first dryer group or on the first dryer cylinder the bottom instead of the top of the web comes into cylinder contact, thereby ensuring easier removal of rejects. As already mentioned, it is particularly important that the web is guided more favorably through the second press station, so that space is gained for at least one further press station, including a third press station used to smooth the web.

The subclaims relate to further refinements of the invention. Detailed explanations of the various inventive ideas can be found in the description of the exemplary embodiments shown in the drawings.

Figur 1

zeigt schematisch in der Seitenansicht eine erfindungsgemäße Naßpressen-Anordnung mit drei Preßstellen.

Figur 2 und 3

zeigen Alternativen mit vier Preßstellen.

Figur 4

zeigt eine andere Alternative mit vier Preßstellen und vorangehender Doppelsiebpartie.

Figur 5

zeigt eine Alternative zu Fig. 1 mit drei Preßstellen.

Figur 6

ist eine Alternative zu den Figuren 2 bis 4 mit vier Preßstellen.

Figur 7

ist eine weitere Alternative zu Figur 1.

Figur 8 und 9

sind Anordnungen mit fünf Preßstellen.

Figuren 10 und 11

sind Anordnungen, bei denen die vom Sieb abgehobene Papierbahn zunächst der glatten Oberfläche eines ersten flexiblen Preßmantels und dann der glatten Oberfläche eines zweiten flexiblen Preßmantels folgt.

Figur 12

zeigt eine weitere Anordnung mit fünf Preßstellen.

Figur 13

zeigt eine Naßpressen-Anordnung mit zwei Preßstellen mit Abnahme der Bahn von einem Obersieb.

Figur 14

zeigt eine ähnliche Anordnung mit zusätzlicher dritter Preßstelle.

Figur 15

ist ähnlich Figur 14, jedoch mit vier Preßstellen.

Figur 16

entspricht Figur 15, jedoch auf fünf Preßstellen erweitert.

Figuren 17 und 18

sind Alternativen zu Figur 16.

Figur 19

entspricht der Anordnung nach Fig. 6, es ist lediglich eine weitere befilzte Preßstelle 8' zwischen die Preßstellen 8 und 14 eingefügt.

Figur 20

zeigt einen Teil der Gestellanordnung und zwei Möglichkeiten der Randstreifenabnahme.

Figur 21

zeigt weitere Möglichkeiten der Randstreifenabnahme.

Figuren 22 und 23

sind Schnitte durch Fig. 21.

Figur 24

zeigt eine alternative Naßpressen-Anordnung mit Abnahmefilz und Abnahmesaugwalze.

Basically applies to the description and for the The following: The technical terms used are to be understood in the scope of all their known variants. For example, the words "felt" or "felt belt" also mean any other type of belt (eg press screen) that serves the purpose of absorbing water that is squeezed out of the paper web. Another example: A "press roll" can have a rotatable roll body (with or without roll cover) or be designed as a so-called shoe press unit with a stationary support body and either with a rotating flexible press belt (which is open on both machine sides) or with a rotating flexible press jacket ( oil-tight on both sides of the machine); in the latter case the shoe press unit is a shoe press roll.

Figure 1

shows schematically in side view an inventive wet press arrangement with three pressing points.

Figures 2 and 3

show alternatives with four press points.

Figure 4

shows another alternative with four press points and preceding twin-wire section.

Figure 5

shows an alternative to Fig. 1 with three pressing points.

Figure 6

is an alternative to Figures 2 to 4 with four pressing points.

Figure 7

is another alternative to Figure 1.

Figures 8 and 9

are arrangements with five press points.

Figures 10 and 11

are arrangements in which the paper web lifted off the screen first follows the smooth surface of a first flexible press jacket and then the smooth surface of a second flexible press jacket.

Figure 12

shows a further arrangement with five pressing points.

Figure 13

shows a wet press arrangement with two press points with removal of the web from a top wire.

Figure 14

shows a similar arrangement with an additional third press point.

Figure 15

is similar to Figure 14, but with four press points.

Figure 16

corresponds to Figure 15, but expanded to five pressing points.

Figures 17 and 18

are alternatives to Figure 16.

Figure 19

corresponds to the arrangement according to FIG. 6, only a further felted press point 8 'is inserted between the press points 8 and 14.

Figure 20

shows a part of the frame arrangement and two possibilities for edge strip removal.

Figure 21

shows further possibilities for edge strip removal.

Figures 22 and 23

are sections through Fig. 21.

Figure 24

shows an alternative wet press arrangement with take-off felt and take-off suction roll.

In all figures, the smooth outer surfaces of the press rolls (7, 15, 33) touched by the web are highlighted by relatively thick lines.

In FIG. 1, a paper web 2 is brought up to a first press point 5 on a wire belt 1 (this touches the underside of the web) via a wire suction roll 3 with suction zone 4. The screen 1 continues over a guide roller 6. The paper web 2 is transferred to the smooth surface of the press roll 7 in the first press point 5 (in which the tensioned screen 1 partially wraps around the press roll 7). The paper web, which adheres to the roller 7 with its upper side, then passes into the second press point 8 between the roller 7 and a further press roller 9. Together with the paper web 2, a press felt 10 (only partially shown) is passed through the press point 8. Its path before and after the press point 8 is determined by felt guide rollers 11. The usual additional devices on the endlessly circulating felt 10, such as are not shown Drainage and cleaning elements (eg pipe suction), felt tensioning roller, regulating roller, possibly other guide rollers; see FIG. 19 for this purpose. The suction suction roll 3 is assigned a water collecting trough 12 with lateral outlet connections 13. In a third press point 14 between the smooth roller 7 and a further smooth roller 15, the paper web 2 adhering to the surface of the roller 7 is pressed again and thereby smoothed; it leaves this press point 14 in contact with the surface of the roller 15 and is removed from the roller 15 in front of a scraper 16, which can be done without the support of the web by train or draft-free by contact with a further (not shown) movable support surface, which the Lane 2 follows after peeling off roller 15 (for example a felt, a dryer fabric, a belt or a roller). Roller 9 is drawn as a tube press roller with a stationary press shoe 17 with a concave pressing surface in the area of the press point 8, over which there is a layer of lubricant in a known manner, on which a flexible tubular press jacket 18 made of plastic slides. The press shoe is radially movable in a known manner in order to be able to vary the press force acting in the press point 8. With regard to the press shoe 17, press rolls of this type are referred to below as "shoe press rolls". In the interest of clarity, the supporting parts such as frames, axles, bearings are not shown; however, see Fig. 20, which shows, inter alia, that the press roll 15 (relative to the press roll 7) is movably mounted.

FIG. 2 shows a wet press arrangement similar to that of FIG. 1. The same parts are again identified by the same numbers. The arrangement in FIG. 2 is expanded by additional components. In the first press point 5, the pressure between screen 1 and roller 7 is generated not only by partially wrapping the tensioned screen 1, but also partially or entirely (as shown) by a pressure element 19. This can be used as a rotating element Roll or be designed as a fixed bar. The pressing element 19 can be moved and pressed radially against the roller 7.

Between press point 14 and scraper 16 there is an additional press point 24 between a press roll 20 with press shoe 23 and circumferential flexible press jacket 25. A press felt 21 is passed through guide press 22 through the press point 24. The symmetrical dewatering of the web in the press point 8 on its underside into the press felt 10 - and in the press point 24 on its upper side in the press felt 21 - ensures minimal structural two-sidedness of the web.

The following also applies to FIG. 1 and to most of the following figures: In the press point 14, little or no water can be removed from the web 2 because there is no water-absorbent felt there. This press point serves to transfer the web 2 from the roller 7 to the roller 15 while smoothing the web. The transfer of roller 7 to roller 15 is effected either by roller 15 having a harder surface than roller 7 and / or by moistening the surface of roller 15 e.g. by means of a doctor blade or a spray tube 26. A water collecting trough (12 in FIG. 1) under the screen suction roller 3 is not shown in FIG. 2, but can be carried out. To increase the drainage capacity, the outer surface of the press sleeves 18 and / or 25 can be provided with fine recesses (e.g. blind bores) (symbolically represented by dashed lines). However, if (on the contrary) relatively low drainage performance is required, the shoe press roll 20 can be replaced with a normal (e.g. grooved) pipe roll.

Figure 3 corresponds in detail to Figures 1 and 2, only the pressure element 19 is missing. For this, the first press point 5 is directly between the rollers 3 and 7 educated. Because of the large diameter of the rollers 3 and 7, pressing can already be carried out with considerable line force in this pressing point, so that the paper web 2 already reaches the second pressing point 8 with a higher dry content, which makes this pressing point 8 more efficient.

FIG. 4 largely corresponds to FIG. 3 in structure and function. Only the two press felts 10 and 21 loop around the press sleeves 18, 25 of the rolls 9 and 20 instead of additional guide rolls at the inlet to the press points 8 and 24. In addition, the screen 1 is the bottom screen of a twin wire former. The paper web 2 is fed between the lower wire 1 and the upper wire 27 to a wide mouth suction device 28 and, together with the wire 27, is deflected upward in an arc in the vacuum slot 29. As a result, the fibers of the web 2 projecting loosely downward into the mesh of the screen 1 are pulled out of the screen 1 and lie flat against the paper web 2 by means of surface tension forces and vacuum action in the suction device 28. In addition, the longer path of sieve 27 relative to sieve 1 causes the two sieves to shift in the running direction, so that the loose fibers in the renewed contact between sieve 1 and web 2 after suction cup 28 no longer fit into the same sieve mesh. As a result of this consolidation of the paper web 2, a higher paper dry content is already achieved at the first press point 5. This also reduces screen markings in web 2. After separation from the web 2, the top wire 27 runs back over guide roll 30 to the forming zone of the former. The width of the slot 29 is preferably between 50 and 150 mm. Several slots over 40 mm wide can also be used.

Figures 5 and 6 show further alternatives to Figures 1 to 4, wherein the press roll 7 is a shoe press roll with press shoe 17, flexible press jacket 18 and jacket cleaning device 44. The roller 9 has a normal tubular roller body. While with the Examples of Figures 1 to 4, the press jacket 18 may contain grooves 47 or blind bores (see FIG. 2) on its outer surface, it is designed in the installation position according to FIGS. 5 and 6 with a smooth outer surface. For this purpose, the outer surface of the roller 9 contains grooves or blind bores, symbolically represented in FIG. 5 by a dashed circle 47.

The pressing force to be applied in the pressing points 5 and / or 14 can be varied in that the flexible pressing jacket 18 is more or less bulged outwards with the aid of radially movable support strips 31, 38. In particular, thanks to the movable bar 38, which cooperates with the normal tube roller 15, an adjustment of the (e.g. four, see Fig. 6) heavy rollers 7, 9, 15 and 20 is not necessary. In other words, this aspect of the invention makes it possible for each of the two pairs of rollers 9 and 7 or 15 and 20 to be rigidly supported on machine frames, foundation plates or the like. Not a single roller has to be stored in swivel levers or the like, e.g. 20 at roller 15. Nevertheless (in Fig. 6) there are four pressing points 5, 8, 14 and 24, the pressing force being individually adjustable in each pressing point. These advantages are also achieved with the designs according to FIGS. 8, 11, 12, 15, 16, 18, 19 and 24. However, the designs are preferred in which there is only a single shoe press roll with a smooth press jacket, in which case a radially displaceable bar cooperates with a normal pipe roll (which rests in immovable bearings), see FIGS. 5-8, 12, 15, 16, 19 and 24.

The sliding surface of the support strip 31 is convexly curved, the radius of curvature determining the degree of bulging of the press jacket 18. The sliding surface of the support strip 38 can also be convexly curved; but also a flat or concave curved sliding surface (similar to the press shoe 17) is possible.

Figure 7 is an alternative to Figure 5, wherein the first press point 5 is located directly between the rollers 3 and 7. Because a higher line force is intended in the press point 5, the flexible press jacket 18 must in turn be supported in the area of the press point 5 by a press bar 31 (guided on the fixed support body of the roller 7, not shown). In order to make it unnecessary to move the large rollers, the strip 31 is expediently designed to be movable radially against the roller 3 and to be able to be pressed against it. A lubricant layer, which is generated hydrostatically or hydrodynamically, ensures that the jacket 18 slides over the bar 31 with little friction. The sliding surface thereof can in turn be convex, flat or concave. In the latter case, the curvature is adapted to the diameter of the roller 3.

Figure 8 is a further development of Fig. 6. In a fifth press point 32 between the rollers 15 and 33, the paper web is smoothed on both sides. In order for the paper web 2 to follow the roller 33 when it leaves the press point 32, the surface layer of the roller 33 is designed to be harder than that of the roller 15. An additional effect of this difference in hardness occurs on the upper side of the paper web 2, which is structured more roughly by felt 21 a stronger smoothing effect than on the underside, so that the outgoing paper web 2 has largely equally good smoothness on both sides. The web 2 continues via guide roller 35 to the dryer section. A scraper 34 cleans the surface of the roller 33. A scraper 16 can be assigned to the roller 15 if necessary.

The surface layer of the roller 15 is preferably harder than that of the press jacket 18. Thus, the surface hardness on roller 15 is higher than on roller 7 and on roller 33 higher than on roller 15. Moistening spray tubes 26 and 36 may be provided in front of the nips 14 and 32 to further facilitate transfer of the web to the desired roll surface. A conveyor belt 37 that runs across the machine width is used to remove the scrap that can occur on the scraper 34. In the pressing points 5 and 14, the flexible press jacket 18 is in turn dented outward by supporting strips 31 and 38.

Figure 9 corresponds to the wet press arrangement according to Figure 8. Only the roller 7 is designed here as a normal tube roller and roller 9 as a shoe press roller with a flexible jacket. Instead of a conveyor belt 37 below the scraper 34, there is only a collecting trough 39 here.

FIG. 10 is a further alternative to FIGS. 1 and 5. Here, the rollers 7 and 15 are shoe press rolls with flexible, smooth, tubular press sleeves 18 and 40. Shoe press roll 7 has a press shoe 17 with a concave sliding surface. Shoe press roll 15 does not yet have such a press shoe because it does not yet form a felted dewatering press nip. It has a support bar 41 and 42 only at the pressing point 14 and opposite the blade of the scraper 16. All the support bars 31, 38, 41, 42 can optionally be rigid or radially movable. Of the two cooperating support strips 38 and 41, usually only one is movable. The width of the press nip 14 can in turn be determined by the shape of the sliding surfaces (convex with any radius or even). It is also possible for one support strip (e.g. 38) to be concave and the other (41) to be convex. The schematically indicated support body 40A of the roller 15 has a recess 40B for a press shoe 25, if such should be retrofitted together with rollers 20, 22 and felt 21 (see FIG. 11).

FIG. 11 is an alternative to FIG. 9, the rollers 7 and 15 being designed as shoe press rollers, as in FIG. 10 but the rollers 9 and 20 as normal tube rollers.

FIG. 12 is another possible variant of FIGS. 8, 9 and 11, roller 7 being a normal tube roller compared to FIG. 11 and roller 9 being a shoe press roller with a flexible circumferential press jacket 18. Below the scraper 34 there is a reject suction nozzle 43. The surface hardness the rollers 7, 15 and 33 are in turn preferably stepped: roller 33 is harder than press jacket 40, and this is harder than roller 7. In a variant of FIG. 12, not shown, the shoe press roller 9 can be replaced by a normal, for example grooved tube roller, namely if a relatively low drainage capacity is sufficient at the pressing point 8.

In FIG. 13, a paper web 2 is fed with a top wire 1 (the upper side of the web is touched by the wire) via a wire suction roll 3 with suction zone 4 to a first pressing point 5, which is arranged only a short distance above the wire suction roll 3. The screen continues from here via a guide roller 6. The paper web 2 is transferred in the first press point 5 to the smooth surface of the press roll 7 and, with its underside adhering to the roll 7, reaches the second press zone 8 between the roll 7 and a further press roll 9. Together with the paper web 2, a Press felt 10 (only partially shown) passed through the press point 8. Before and after the pressing point, the felt 10 runs over guide rollers 11. The rest of the endless felt loop along with the usual associated components is not shown. The suction suction roll 3 is assigned a water collecting trough 12 with two lateral outlet connections 13. The roller 6 can be moved horizontally to open and close the press point 5 - and to vary the contact distance of the screen 1 on the press roll 7 - as indicated by a double arrow. The circumference of the roller 7 is cleaned by a scraper 46. The sieve 1 runs in Difference from Figures 1-12 counterclockwise by (arrows). The direction of travel of the felt 10 through the pressing point 8 deviates only slightly from the horizontal. Therefore, a dryer fabric roller 54 can be arranged directly next to the roller 7, over which a dryer fabric 53 runs. This transports the web 2 in a known manner to a first drying cylinder 57, which contacts the underside of the web, and via further rollers and cylinders, of which only the roller 58 is visible.

In FIG. 14, the wet press arrangement of FIG. 13 is expanded by a further feltless press point 14, in which the roller 15 pressed against the paper web 2 is used to smooth the top of the paper web 2, which has become rough due to the felt 10. Scraper 46 on roller 7 can be omitted in some cases. Scrap material accumulating on the scraper 16 is transported laterally out of the machine by the conveyor belt 37.

In Figure 15, a second shoe press roll 20 with felt 21 is added. In addition (contrary to FIG. 14) roller 7 is a shoe press roller and roller 9 is a normal tube roller. Radially movable support strips 31 and 38 transmit the pressing forces in the pressing points 5 and 14 to the flexible jacket 18 of roller 7.

In FIG. 16, in comparison to the arrangement in FIG. 15, a further press roll 33 with a hard, smooth surface is provided. The upper side of the paper web 2 roughened by the felt 10 is smoothed in the pressing point 32. The hardness of the outer layers of the rolls increases in the running direction from roll 7 via roll 15 to roll 33.

In the case shown, roller 20 is not a shoe press roller; the third press zone 24 is therefore not an extended press zone in this example. A moistening spray tube 36 additionally ensures the transfer of the web from the press roll 15 on the press roller 33. Roller cleaning devices 44 are provided for the continuous or discontinuous cleaning of the rollers 7 and 15. The scraping material accumulating on the scraper 34 falls down, for example into a reject chest.

An alternative embodiment of the press according to FIG. 16 is shown in FIG. It differs in that roller 7 is a rigid tube roller and roller 9 is a shoe press roller. In addition, roller 20 is also a shoe press roller; in this roller as well as in principle in every roller lying in a felt, the outer surface in contact with the felt can be provided with grooves or blind bores (as shown at 47, FIG. 16).

Figure 18 is another alternative to Figures 16 and 17, in which the two rolls 7 and 15 are shoe press rolls.

In Figure 19 one of a porous tape 1, e.g. Sieve belt, transported paper web 2 dewatered or smoothed in five pressing points. Then, guided by a drying wire 53, it reaches the first drying cylinder 57.

On the belt 1, the paper web 2 is guided around a suction roll 3 with suction zone 4 into a first press point 5 between roll 3 and roll 7. After the press point 5, the belt 1 runs over the guide roller 6, while the paper web 2 continues on the outer surface of the press jacket 18 of the shoe press roller 7 to a second press point 8. The pressing force in the first pressing point 5 is exerted by a pressure bar 31 (which is radially displaceable in the stationary support body of the roller 7, not shown). The press point 8 is formed by the pressure shoe 17, which is also radially displaceable and presses on the paper web 2 from one side via a lubricating film and press jacket 18, and by counter-roller 9 which presses on the press felt 10 from the other side presses on the paper web. The press felt 10 runs over guide, regulating and tensioning rollers 11, 48 and 52 back to the press inlet on the roller 9. The roller 48 has a scraper 49. A spray tube 50 is used for washing the felt 10, and for removing the press and wash water Pipe suction device 51. An additional supplementary press point 8 'identical to the second press point 8' is provided with exactly the same elements as the press point 8, which are identified by the "dash" in the numbering. This supplementary press point is an option for paper webs that are difficult to drain. The web passes from the press point 8 'into the ("third") press point 14 between the rollers 7 and 15 and adheres to the surface of the roller 15 in another ("fourth") press point 24 between the rollers 15 and 20.

In the press point 24, the web 2 is pressed by a press shoe 23 via a lubricating film, press jacket 25 and felt 21 onto the press roll 15 and continues on its surface to a separation point "A", from which it is sucked onto the drying wire 53 . This is done by means of the suction zone 55 of the suction guide roller 54. A further suction device 56 can be installed in order to prevent the web 2 from detaching from the drying wire on the route from the suction guide roller 54 to the first drying cylinder 57. From the first drying cylinder 57, the paper web 2 passes together with the drying wire 53 via a drying wire guide roller 58 to the second drying cylinder 57A etc. The press felt 21 is detached from the paper web 2 behind the press point 24, via a guide roller 22 to a doctor roller 60 and further via a tension roller 64, regulating roller 65 and another guide roller 22 to get back to the press point 24. The scraper roller 60 is cleaned by a scraper 61, the felt 21 by the spray tube 62. Splash water and press water are sucked off by means of pipe suction 63.

In FIG. 20, a paper web 2 is guided on a belt 1 over roller 3 into a first press point 5 between belt 1 and the smooth pressing surface of roller 7. Volume 1 there delivers the paper web 2 to the roller 7 and runs over roller 6 to further process stations, not shown, in order to finally return again with a web 2 in the direction of roller 3. Adhering to the surface of the roller 7, the paper web 2 passes into a second press point 8 and a third press point 14 between the roll 7 and the roll 15, the circumference of which leaves it in front of the scraper 16. The second press point 8 is formed between the rollers 7 and 9. A press shoe 17 presses the press jacket 18 and a felt 10 against the paper web 2 supported by the roller 7. The felt 10 detaches after the press point 8 from the paper web 2 and overflows Guide roller 11 downwards. He returns from the bottom left with the jacket 18 to the press point 8. By pressing the guide roller 6 horizontally to the right, the press point 5 is closed (operating position); by moving the guide roller 6 to the left, it can be opened. On both sides of the machine, stands 66 carry a bearing block 69, on which the roll neck 70 of the press roll 7 is supported, via removable intermediate pieces 67 and brackets 68. The bearing pin 70 either rotates with the roller 7 or is stationary when roller 7 is a deflection compensation roller.

The stands 66 stand on foundation plates or supports 71. A press 73 with pivot bolts 74 is attached to both sides of the machine on press frames 72 which are only shown as a partial piece. On this bolt 74, the press lever 75 is pivotally attached, which holds the roller bearing 78 in which the axis 79 of the press roll 15 is mounted. A sprue 80 of the bearing housing 78 has bearing bores 81 for the pivot pins of the scraper 16 and 82 for articulating the piston rod of the hydraulic cylinder 83. On the opposite side, the hydraulic cylinder 83 is connected to the bearing block 69 via a bearing bracket 84. With one on the driver's side and drive side of the machine mounted hydraulic cylinder 83, the press roll 15 is either swiveled to the right of the press roll 7 or pressed to the left (operating position).

A pair of rollers 85, 86 is also shown in FIG. 20 at the top left, over which an endless smooth belt 87 rotates at approximately the same speed as belt 1. The tape 87 is pressed by the roller 85 onto an edge strip sprayed off from the paper web to be processed further by means of the water nozzle 76 and carries it away with it to the roller 86, on the circumference of which a scraper 88 scrapes the edge strip 99 into a collecting trough 89. Dilution water from a nozzle arrangement 90 rinses the edge strip out of the tub 89 through a lateral outlet connection 91. A moistening spray tube 92 moistens the tape surface in the return. As an alternative to the edge strip removal device 85 to 92, the edge strips can also be held in place by a suction pad 105 with a vacuum connection 105 'at the pressing point 5, so that they continue to run with the belt 1, while the center of the web runs along with the surface of the roller 7. Another alternative to edge strip removal is by scraping off the surface of the roller 7 by means of edge scrapers 103.

FIG. 21 shows another arrangement, in which a screen 1 feeds a paper web 2 over a roller 3 from bottom to top to a first press point 5 and continues via guide roller 6. The paper web 2 reaches the circumference of the roller 7 through the press point 8 and is detached from the roller 7 in front of the scraper 46. Felt 10 runs through the press point 8 and continues via guide roller 11. In front of the roller 3, a roller 93 is pressed against the edge strip 99 of the web 2 and lifts it off the screen 1. Edge strip parts which are not thrown off the roller 93 by centrifugal force are scraped off by a scraper 94. Roller 93 rotates about axis 95 and is synchronized with the speed of the screen 1 Peripheral speed driven (Fig. 21 and 22).

Another possibility of edge strip removal is shown further to the left (FIGS. 21 and 23). The edge strip 99 is sprayed out of the sieve by a spray pipe 98. Partitions or better still suction pad 96 ensure that the edges of the web to be continued are also not detached from the screen by the spray water of the spray tube 98. The suction box 96 is evacuated via line 97.

22 shows in cross section the screen 1 and the web 2 adhering to it, as well as the edge strip 99 separated from it. Such edge strips 99 (as shown) usually become thinner and weaker towards the outermost edge and would cause web breaks if they were not would cut off from lane 2 in time. The edge strip 99 comes with the surface of the roller 93 to the scraper 94. The axis of the roller 93 is slightly inclined, the roller 93 is pressed against the resilient screen 1. The roller 93 can alternatively be designed with a conical outer surface instead of a cylindrical one (truncated cone).

In FIG. 23 (section XXIII of FIG. 21) the web 2 and the severed edge strip 99 hang on the screen 1. The edge of the paper web 2 is held by the edge suction device 96 with suction nozzle 97, through which air is extracted. A spray pipe 98 with nozzles 98 'is fed with pressurized water. The water emerging from the nozzles is sprayed onto the screen 1 and detaches the edge strip 99 from the latter.

In FIG. 24, just like in FIG. 15, a paper web 2, hanging on a porous belt, reaches the suction roll 3 with suction zones 4 and 4 'and is transferred to the circumference of the shoe press roll 7 in the first press point 5. Volume 1 runs over guide, tensioning and regulating rollers 6, 100 and 102 to a take-off suction roller 104, which draws the paper web 2 over from a web forming screen 101 onto the belt 1. Band 1 is cleaned by spray tube 106 and sucked through slot suction device 107. Band 1 can be a sieve (press sieve) or needle felt or the like. In the press point 5 (by the interaction of the press roll 3 with the radially movable bar 31), water pressed out is collected in the tub 12 and drained through the lateral outlet 13. After the press point 5, the paper web 2 follows the surface of the roller 7 and is pressed again in the press nip 8. The pressing force acts on the one hand from a lubricated press shoe 17 through a flexible press jacket 18 on one side of the paper web 2, and on the other hand from the press roller 9, which is held with its pins 109 in blocks 110, via the press felt 10 on the other side of the paper web. The felt 10 runs over guide rolls 11 and over tensioning roll 52 and regulating roll 48 back to the press roll 9. The paper web 2 runs with the smooth surface of the press cover 18 of the roll 7 through a third press point 14 (on a further radially movable bar 38) and from here with the smooth surface of the normal tube roller 15 by a fourth pressing point 24, which is formed between the rollers 15 and 20. The web 2 is detached from the surface of the roller 15 and fed to the subsequent treatment units. A scraper 16 with a collecting trough 39 cleans the surface of the roller 15.

The paper web is pressed against the roller 15 by means of the shoe press roller 20, namely by means of a radially movable press shoe 23 via the flexible press jacket 25 and the press felt 21, which is guided over guide rollers 22. The press shoe 23 is supported on a stationary support body, from which a pin 111 is visible. The bearing blocks 110 supporting the two pins 109 of the press roll 9 are connected via intermediate pieces 112 to a stationary cross member 113 which is part of a (for the sake of Clarity is not shown) press frame. The bearing blocks 115 holding the pins 114 of the stationary support body of the roller 7 are connected to the bearing blocks 110 by means of tie rods 116. When changing the felt, roller or jacket, the tie rods 116 can be removed or their length interrupted.

A similar arrangement also exists for the pair of rollers 15/20. Base plates 118 rest on foundation plates or machine substructures 117, and intermediate pieces 119 rest on them. Bearing blocks 120 rest on them, in which the already mentioned pins 111 of the roller 20 are mounted. The pins 122 of the roller 15 are mounted in bearing blocks 121 and these are in turn connected to the bearing blocks 120 by means of removable tie rods 123.

Again, thanks to the movable bar 38, it is possible for each of the two pairs of rollers 7, 9 and 15, 20 to be supported in immobile bearing blocks 110/115 and 120/122; i.e. a movable roller bearing (similar to that of Fig. 20) is unnecessary. The result is an extremely compact press section, with two felted, high-capacity dewatering presses, namely with the second press 8 for dewatering one side of the web, and with the fourth press 24 for dewatering the other side of the web, and in between with the feltless third press 14 for smoothing and turning the web. If necessary, the smooth tube roll 15 with an additional (not shown) smooth tube roller can form a final press nip for a further smoothing of the web, in order to achieve the highest web quality.

Claims (39)

1. Process for dewatering a fibre web delivered by means of a continuous belt, in particular in a paper manufacturing machine, in which the web is guided in an essentially horizontal movement direction of the machine, comprising the following features:

   a) the web (2) is guided, essentially in the movement direction of the machine, between the belt (1) and a smooth casing surface (7) through a first press point (5) and thereafter between the smooth casing surface and a felt web (10), through a second press point (8);

   b) the web (2) is guided, after the second press point (8) between the smooth casing surface (7) and a second smooth casing surface (15), through a third press point (14),

   and the process is characterised in that
   c) the web (2) in the second press point (8) is guided through an extended press gap formed by means of a shoe-press roller (9), and the web (2) is behind the third press point, again essentially in the horizontal direction, either removed from the second smooth casing surface or between the second smooth casing surface and a second felt web (21), guided through a fourth press point (24).
2. Process for dewatering a fibre web delivered by means of a continuous belt (for example sieve belt 1), in particular in a paper manufacturing machine, by means of which the web is guided in an essentially horizontal movement direction of the machine, comprising the following features:

   a) the web (2) is guided, between the web (1) and a smooth casing surface (7), through a first press point (5) and thereafter between the smooth casing surface and a felt web (10) essentially in the horizontal direction, through a second press point (8);

   b) the web (2) is after the second press point (2) guided between the smooth casing surface (7) and a second smooth casing surface (15) through a third press point (14),

   and the process is characterised in that
   c) the web (2) is, whilst running through at least one of the press points (5, 8, 14, or 24) and therebehind, held in contact with the outer smooth casing surface of the flexible press casing (18 or 40) of a shoe-press roller (7 or 15), and the web (2) is guided, again essentially in the horizontal direction, behind the third press point, either removed from the second smooth casing surface or between the second smooth casing surface and a second felt web (21), through a fourth press point (24).
3. Process according to Claim 2, characterised in that the flexible press casing (18 or 40) is pressed by means of a radially displaceable ledge (38 or 41 or 42) against the smooth casing surface of a press roller (15 or 7 or 33).
4. Wet-press arrangement for dewatering a fibre web (2), in particular in a paper manufacturing machine, by means of which the web is guided essentially in the horizontal movement direction of the machine, comprising a continuous belt which delivers the web and with the following features:

   a) a first press roller (7) has a smooth casing surface which has direct contact with the web (2);

   b) at the periphery of the first press roller (7) are formed at least three press points (5, 8, 14) which are successively passed through by the web (2) and between which the web adheres to the smooth casing surface;

   c) the first press point (5) is established between the first (smooth) press roller (7) and the web (1);

   d) a continuous press felt (10), which separates itself from the web behind the second press point, moves essentially in the horizontal direction through the second press point (8) which is established between the first press roller (7) and a second press roller (9);

   e) the first press roller (7) together with a third smooth press roller (15) form a third press point (14);

   characterised by the following additional features:

   f) the second press roller (9) is a shoe-press roller, so that the second press point (8) is arranged to be a press gap which is extended in the movement direction of the web;

   g) the arrangement is such that the web (2) runs, behind the third press point, again essentially in the horizontal direction, either off the third press roller (15) or, together with a second felt web (21) between the third press roller (15) and a fourth press roller (20), through a fourth press point (24).
5. Wet-press arrangement for dewatering a fibre web (2), in particular in a paper manufacturing machine, through which the web is guided essentially in the horizontal movement direction of the machine, comprising a continuous belt which delivers the web. and with the following features:

   a) a first press roller (7) has a smooth casing surface which makes direct contact with the web (2);

   b) at the periphery of the first press roller (7) are formed at least three press points (5, 8, 14) which are successively passed through by the web (2) and between which the web adheres to the smooth casing surface;

   c) the first press point (5) is established between the first (smooth) press roller (7) and the web (1);

   d) through the second press point (8), established between the first press roller (7) and a second press roller (9), moves essentially in the horizontal direction a continuous press felt (1) which separates itself from the web behind the second press point;

   e) the first press roller (7) together with a third smooth press roller (15) form a third press point (14);

   characterised by the following additional features:

   f) at least one of the smooth press rollers (7 or 15) is developed as a shoe-press roller with an externally smooth flexible press casing (18 or 40) which moves around a stationary support element (114);

   g) the shoe-press roller (7 or 15) has a press shoe (17 or 45), which is radially displaceable relative to the support element and provided with a concave glide surface, which presses the pressure casing (18) against one of the press rollers (9 or 20) for the purpose of forming an extended and felted press gap (8 or 24;

   h) the shoe-press roller is additionally fitted with a ledge (38 or 41, 42), which is displaceable relative to the carrier, which presses the press casing (18) or (40) against a smooth press roller (15 or 7, 33) for the purpose of establishing a feltfree press gap (14 or 32).
6. Wet-press arrangement according to Claim 5, characterised in that the first press roller (7) is a shoe-press roller.
7. Wet-press arrangement according to Claim 5, characterised in that the third press roller (15) is a shoe-press roller.
8. Wet-press arrangement according to Claim 6, characterised in that the shoe-press roller (7) comprises a further ledge (31), which is displaceable relative to the carrier element and which can press the press casing (18) against the belt (1) for the purpose of forming the first press gap (5).
9. Wet-press arrangement according to Claim 4 or 6, characterised in that the third press roller (15) comprises a rotary roller element.
10. Wet-press arrangement according to Claim 9, characterised in that the smooth casing surface of the third press roller (15) is formed by a plastic cover, a stone element or the like.
11. Wet-press arrangement according to Claim 4 or 5, characterised in that the third (smooth) press roller (15) together with a fourth press roller (20) establish a fourth felted press gap (24).
12. Wet-press arrangement according to Claim 11, characterised in that the fourth press gap (24) is arranged to be a press gap which is extended in the movement direction of the web.
13. Wet-press arrangement according to Claim 11 or 12, characterised in that the web and a continuous press felt (21) pass essentially in the movement direction of the machine through the fourth press gap (24).
14. Wet-press arrangement according to Claim 4 or 7, characterised in that the first press roller (7) comprises a rotary roller element, i.e. it is arranged as a "normal tubular roller".
15. Wet-press arrangement according to Claim 14, characterised in that the smooth casing surface of the first press roller (7) is formed by a plastic coating, preferably by an elastomer layer,
16. Wet-press arrangement according to Claim 4 or 5, characterised in that the smooth casing surface of the third press roller (15) is harder than the one of the first press roller (7).
17. Wet-press arrangement according to Claim 4, 5 or 16, characterised in that a moistening spray pipe (26) is arranged on the smooth casing surface of the third press roller (15) ahead of the third press point (14).
18. Wet-press arrangement according to Claim 4 or 5, characterised in that behind the fourth press point (24) is formed a fifth press point (32), i.e. between the third press roller (15) and a fifth press roller (33).
19. Wet-press arrangement according to Claim 18, characterised in that the smooth casing surface of the fifth press roller (33) is harder than that of the third press roller (15).
20. Wet-press arrangement according to Claim 18 or 19, characterised in that a moistening spray pipe (36) is arranged on the smooth casing surface of the fifth press roller (33) in front of the third press point (32).
21. Wet-press arrangement according to Claim 4 or 5, characterised in that on at least one of the smooth press rollers (7, 15, 32) is arranged a cleaning mechanism (44), for example a spray pipe and/or a brush roller and/or stripper and/or scraper (16, 34, 36, 46).
22. Wet-press arrangement according to Claim 21, characterised in that the cleaning mechanism comprises a device for removing dirt and/or paper waste which extends over the entire width of the machine, for example conveyer belt (37), collecting trough (39) and/or vacuum nozzle (43).
23. Wet-press arrangement according to Claim 7, characterised in that the third press roller (15), designed as a shoe-press roller, comprises a further ledge (42), which is displaceable relative to the carrier and can press the press casing (40) against a fifth press roller (33) for the purpose of establishing a fifth press gap (32) (Figure 11, 12 or 18), and the fifth press roller (33) is a normal tubular roller.
24. Wet-press arrangement according to Claim 6, characterised in that the shoe-press roller comprises an additional press shoe (17'), which is radially displaceable relative to the carrier and provided with a concave glide surface, which can press the press casing against an additional press roller (9') for the purpose of establishing an additional extended and felted press gap (8').
25. Wet-press arrangement according to Claim 4 or 5, characterised in that the first press roller (7) makes contact with the top surface of the web.
26. Wet-press arrangement according to Claim 4 or 5, characterised in that the first press roller (7) makes contact with the bottom surface of the web.
27. Wet-press arrangement according to one of Claims 4 to 26, characterised in that the casing surface of the press roller (9 or 20), which supports the individual continuous press felt (10 and/or 21) in the respective press point (8 or 24), comprises cutouts (grooves or pocket bores 47).
28. Wet-press arrangement according to one of Claims 4 to 27, characterised in that the individual continuous press felt (10 and/or 21) is, prior to entry into the respective press point (8 or 24), guided directly through the casing surface of the respective press roller (9 or 20).
29. Wet-press arrangement according to Claim 4 or 11, characterised in that the press planes of both the second press point (8) and the fourth press point (24) are at least virtually parallel to each other and preferably at least virtually vertically arranged.
30. Wet-press arrangement according to one of Claims 4 to 29, characterised in that in the first press point (5) a convex section of the smooth casing surface of the first press roller (7) diverts the sieve belt (1), so that the sieve tension generates a press load on web (2).
31. Wet-press arrangement according to one of Claims 4 to 31, characterised in that on the first press point (5) inside the loop of the sieve belt (1) is arranged a press element (ledge or roller 19).
32. Wet-press arrangement according to Claim 31, characterised in that the press element is a suction roller (3).
33. Wet-press arrangement according to one of Claims 4 to 32, characterised by a device, arranged in front of the first press point (5), for the removal of edge strips (99) separated at the sieve belt (1) from the web (2).
34. Wet-press arrangement according to one of Claims 4 to 32, characterised in that the first press roller (7) comprises on both roller ends outside the smooth casing surface which is touched by the web (2) a respective edge zone, i.e. in the area of the edge strips separated from the web (2) at the sieve belt (1), and characterised by a design of the edge zones which prevents adherence of the edge strips to the first press roller.
35. Wet-press arrangement according to Claim 34, characterised in that the edge zones comprise a surface which repels the edge strips.
36. Wet-press arrangement according to Claim 5 or 8, characterised in that the ledge (31; 38; 41; 42) comprises a convex curved glide surface for the press casing.
37. Wet-press arrangement according to Claim 36, characterised in that the curvature radius of the glide surface is equal to, or preferably smaller than the radius of the rotary path of the press casing.
38. Wet-press arrangement according to Claim 7, characterised in that the stationary carrier (40A) of the shoe-press roller (15) comprises a receiving mechanism (40B) for a radially displaceable press shoe.
39. Wet-press arrangement according to one of Claims 4 to 38, in which at least a portion of the press rollers (7, 9, 15, 20) has different roller diameters, characterised in that the largest roller diameter is maximum 2 times, preferably maximum 1.6 times the nearest smaller roller diameter.

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