SEALING ELEMENTS IN A TWIN-WIRE PAPER MACHINE

Abstract

Twin-wire presses are disclosed for dewatering fiber suspensions comprising endless upper and lower wires defining a dewatering space, upper and lower wire guides for guiding the wires obliquely towards the inlet end of the dewatering space, and upper and lower wedge-shaped seals extending from an inlet box towards the dewatering space inlet to create a seal in the tapering space between the wires and the fiber suspension entering the dewatering space. The inner surfaces of the wedge-shaped seals define a passage for the fiber suspension and the outer surfaces extend at an acute angle towards the inner surfaces so that at least part of the seals are sealed against the wires and the distance between the inner surfaces of the seals is substantially equal to the distance between the wires at the dewatering space inlet.

Description

FIELD OF THE INVENTION

The present invention relates to a twin-wire press.

BACKGROUND OF THE INVENTION

Twin-wire presses for the dewatering of a fiber suspension and forming of a continuous web thereof are previously known. Dewatering of the pulp is usually done from an inlet pulp concentration of from 3 to 8 percent by weight to an outlet pulp concentration of from 30 to 50 percent by weight. According to the state of the art, such twin-wire presses comprises lower rolls, an endless lower wire running in a path around the lower rolls, upper rolls, and an endless upper wire running in a path around the upper rolls. The two wires co-operate with each other along dewatering sections of these paths, in which the wires form a wedge-shaped dewatering space for the fiber suspension between each other. During displacement of the wires along these dewatering sections, the wires thus successively compresses the fiber suspension in the wedge-shaped dewatering space, whereby the fiber suspension is initially pressed and dewatered and formed into a continuous fiber web between the wires.

An inlet box provides for supply of the fiber suspension to the wedge-shaped dewatering space between the wires. The known twin-wire presses further comprise two dewatering tables supporting the respective wires in these dewatering sections of the path, such that the wedge-shaped dewatering space is formed between the wires, and a roll arrangement is situated after the dewatering tables, as seen in the direction of movement of the wires, for finally pressing and dewatering of the fiber web between the wires, so that the fiber web will obtain a desired dryness. Alongside the longitudinal direction of the wires, in the wedge-shaped dewatering space, there are perforated dewatering elements that are arranged against the wires outside the dewatering space. Formed filtrate thus flows through the wires and the perforated dewatering elements and is led away to upper and lower outlet boxes, respectively, arranged at the dewatering tables. The upper and lower outlet boxes, respectively, may be divided into several chambers, whereby a filtrate that flows through the upper and lower dewatering elements, respectively, may be divided into partial filtrate in two or more chambers in the respective outlet boxes.

A traditional twin-wire press comprises sealing members in the shape of an upper resilient sealing blade, that extends from the inlet box into the wedge-shaped dewatering space, where it is sealingly arranged against the upper wire, and a lower resilient sealing blade, that extends from the inlet box into the wedge-shaped dewatering space, where it is sealingly arranged against the lower wire. Between the upper and lower sealing blades is formed a passage for the fiber suspension between the inlet box and the wedge-shaped dewatering space. The ends of the sealing blades are usually located a short distance into the dewatering space. The sealing blades usually have a thickness of about 1.5 to 2 mm.

The geometry for the inlet box with adjusting sealing blades in the conventional twin-wire press, for supply of the fiber suspension to the wedge-shaped dewatering space between the wires, is very complicated to set in order to obtain the correct and desired flow of the fiber suspension. This geometry is thoroughly tested by many tests and trials during a long period before the twin-wire press is put into operation. The geometry for the inlet box and the distances between the sealing blades are thus fixed. An increase in the thickness of the sealing blades results in a decreased distance between the blades, which consequently is not desired. In addition, since the free ends of the sealing blades bear against the insides of the wires in the dewatering space, thus results in a limited possibility of raising and lowering the dewatering tables in order to change the geometry in the wedge-shaped dewatering space. Hence, the thickness of the sealing blades implies a limitation with respect to the possibility to be able to produce fiber webs in the twin-wire press having different grammage, and in particular lower grammages.

It is also necessary that the known sealing blades be resilient, because they should seal and press sufficiently against the wire owing to the overpressure that is created by the passing fiber suspension. The sealing blades are extending along the whole width of the machine, which is usually four to five meters. It is also complicated and time-consuming to straighten the sealing blades in order to achieve a correct straightness such that they bear against the insides of the wires. In that respect, it is also difficult and time-consuming to change the sealing blades, which must be done during stoppage of production, which implies wasted production time, and thus another added cost.

In order to be able to manage the aggressive environment, the prior known sealing blades are made of acid-proof steel. In spite of the fact that the sealing blades are made of steel, however, they are worn out relatively quickly, due to certain fillers that are present in the white water that is recirculated from the paper machine to the fiber raw material. It occurs inter alia from precipitation in the form of carbides on the steal sealing blades. An increase of the hardness of the sealing blades such that they exceed the hardness of the carbides, in order to decrease the wear on the sealing blades, means that the necessary resilient properties of the sealing blades are lost.

If the wear of the known sealing blades becomes too large, the wires may be damaged, and in a worst case, break down. For this reason, the sealing blades must be changed in due time, and preferably before the risk of damage to the wire may arise. As a consequence of wear of the sealing blades during operation in the twin-wire press, their actual life is relatively short. Obviously, from the above description, installation and change of the sealing blades are time-consuming and thus costly. Since the known sealing blades are made of steel, they are also very difficult to produce and hence expensive.

In twin-wire presses of the kind mentioned above, also wire guiding members are utilized, which are arranged at the inlet section of the twin-wire press. They are made up of a respective bent sheet metal, against which the respective wire runs, and replaces those rolls that traditionally are used at an inlet section of a twin-wire press. Wear also occurs on the wire guiding members and there is a risk that the wires can be damaged during too large an extent of wear on the wire guiding members. The wire guiding members are in themselves expensive. Installation and exchange of the wire guiding members are also time-consuming and costly.

One of the objects of the present invention is to at least partially eliminate those drawbacks associated with the state of the art as mentioned above. One object in accordance with the present invention is to achieve improved sealing members for a twin-wire press. In particular, it is another object to achieve sealing members having a longer lifetime and/or to achieve a simpler and faster exchange of sealing members in a twin-wire press. Yet another such object is to be able to adjust the geometry of the wedge-shaped dewatering space between the dewatering tables to a larger extent. Yet another object is to reduce the wear of the sealing members. In addition, another object is to decrease the cost for exchange and production of the sealing members in a twin-wire press. In addition, an object is to also decrease the cost for exchange and production of the wire guiding members in a twin-wire press.

SUMMARY OF THE INVENTION

In accordance with the present invention, these and other objects have now been realized by the invention of a twin-wire press for dewatering a fiber suspension comprising an endless lower wire and an endless upper wire defining an elongated dewatering space therebetween having an inlet end and an outlet end for dewatering the fiber suspension during simultaneous displacement of the endless upper and lower wires, an inlet box for supplying the fiber suspension to the inlet end of the elongated dewatering space, upper and lower perforated dewatering elements disposed against the sides of the endless upper and lower wires outside of the elongated dewatering space, an upper outlet box for collection of filtrate flowing from the elongated dewatering space through the upper wire and the upper perforated dewatering element, a lower outlet box for collection of filtrate flowing from the elongated dewatering space through the lower wire and the lower perforated dewatering element, an upper wire guiding member arranged to guide the endless upper wire obliquely downwardly towards the inlet end of the elongated dewatering space, a lower wire guiding member arranged to guide the endless lower wire obliquely upwardly towards the inlet end of the elongated dewatering space, whereby a tapering space is formed between the upper and lower wire guiding members, and upper and lower wedge-shaped sealing members extending from the inlet box towards the inlet end of the elongated dewatering space for creating a seal in the tapering space between the endless upper and lower wires and the fiber suspension entering the elongated dewatering space, the upper and lower wedge-shaped sealing members defining a passage therebetween for the fiber suspension flowing to the elongated dewatering space from the inlet box, each of the wedge-shaped upper and lower sealing elements including an inner surface defining part of the passage for the fiber suspension and an outer surface extending at an acute angle towards the inner surface, at least part of the wedge-shaped upper and lower sealing elements sealingly disposed against its respective upper and lower wire, the distance between the inner surfaces of the upper and lower wedge-shaped sealing elements forming the passage for the fiber suspension being substantially equal to the distance between the upper and lower wires at the inlet end of the elongated dewatering space. In a preferred embodiment, the at least part of each of the upper and lower wedge-shaped sealing elements is sealingly disposed against its respective upper and lower wire only at the location of the respective upper and lower wire guiding member corresponding thereto.

In accordance with one embodiment of the twin-wire press of the present invention, the inner and outer surfaces of each of the upper and lower wedge-shaped sealing elements tapers into a narrow, tongue-shaped portion towards a free end of the respective upper and lower wedge-shaped sealing elements in abutment against the inner surfaces of the upper and lower wires, respectively.

In accordance with another embodiment of the twin-wire press of the present invention, each of the upper and lower wedge-shaped sealing elements and the corresponding upper and lower wire guiding members includes adjacent oblique portions abutting against each other with the upper and lower endless wires therebetween.

In accordance with another embodiment of the twin-wire press of the present invention, the upper and lower wedge-shaped sealing elements comprise a polymer.

In accordance with another embodiment of the twin-wire press of the present invention, each of the upper and lower wedge-shaped sealing elements is horizontally adjustable against each of the respective upper and lower wire guiding members in the longitudinal direction of the twin-wire press.

In accordance with another embodiment of the twin-wire press of the present invention, the upper and lower wire guiding members are vertically adjustable against the upper and lower wedge-shaped sealing elements.

In accordance with another embodiment of the twin-wire press of the present invention, the upper and lower wire guiding members include wear element portions disposed against the upper and lower endless wires respectively.

In accordance with another embodiment of the twin-wire press of the present invention, the upper and lower wire guiding members are integrally attached to the upper and lower perforated dewatering elements.

In accordance with another embodiment of the twin-wire press of the present invention, the upper and lower wire guiding members are integral with the upper and lower perforated dewatering elements, respectively.

The objects of the present invention are thus achieved by the invention of a twin-wire press for dewatering of a fiber suspension, according to the present invention, which comprises an endless lower wire and an endless upper wire, that defines an oblong dewatering space, in which the fiber suspension will be dewatered during displacement of the wires. Furthermore, the twin-wire press comprises an inlet box for supply of fiber suspension to the dewatering space, at an inlet end of the dewatering space, lower and upper perforated dewatering elements that are arranged against the wires outside of the dewatering space, an upper outlet box for collection of filtrate that flows from the dewatering space through the upper wire and the upper perforated dewatering element, and a lower outlet box for collection of filtrate that flows from the dewatering space through the lower wire and the lower perforated dewatering element. An upper wire guiding member is arranged to guide the upper wire obliquely downwards towards the inlet end of the dewatering space, a lower wire guiding member arranged to guide the lower wire obliquely upwards towards the inlet end of the dewatering space, such that a tapering space is formed between the upper and lower wire guiding members. Furthermore, the twin-wire press comprises upper and lower sealing members extending from the inlet box, for sealing between the wires and the fiber suspension that enters into the dewatering space. The upper and lower sealing members delimit a passage between each other for the fiber suspension, which flows to the dewatering space from the inlet box. The sealing members comprise an upper wedge-shaped sealing element, that in the tapering space between the upper and lower wire guiding members is sealingly arranged against the upper wire, and a lower wedge-shaped sealing element, that in the tapering space between the upper and lower wire guiding members is sealingly arranged against the lower wire. Each sealing element presents a first side, that delimits part of the passage for the fiber suspension, and a second side, that extends with an acute angle towards the first side and that is arranged to at least in part be sealingly arranged against the associated wire. The twin-wire press is characterised in that the sealing elements are arranged with a substantially equal distance between the first sides of the respective sealing element, which forms the passage for the pulp suspension from the inlet box to the dewatering space, as compared to the distance between the upper and lower wires at the inlet end of the dewatering space.

Exchange and assembly of the sealing elements in a twin-wire press are less complicated compared to the conventional sealing blades, which required accurate straightening. In accordance with the present invention, the cost for production of the sealing elements is decreased, as well as installation and exchange in a twin-wire press, since the time for stoppage of production can be lowered considerably, in comparison with traditionally used sealing blades. In addition, the cost for exchange and production of the wire guiding members for use in a twin-wire press may also be decreased, if according to an embodiment of the present invention, they are formed as wearing parts, as will be evident in more detail below.

When we in the following description mention is made that a sealing element is arranged “sealingly against” a wire guiding member, it is intended by this expression that a wire is arranged between the sealing element and the wire guiding member.

By the expressions “wedge-shape” and “wedge-shaped”, concerning the design of the sealing element according to the present invention, it is intended that the sealing element have a tapering shape. This also means that the sealing element may have chamfered shapes. Thus, that the sealing element have a wedge-shape comprises a surface that is oblique in comparison to another opposite or adjacent surface of the sealing element, as described in detail in the following description. However, the tapering form needs not be continuously tapering.

Each respective sealing element is arranged sealingly only against the respective wire guiding member according to an embodiment of the present invention. Thus, the sealing members according to the present invention do not need to project into the dewatering space, as in the case with conventional sealing blades. In that respect, the same distance can be obtained between the upper and lower sealing members in the passage of the fiber suspension from the inlet box to the dewatering space, as between the upper and lower wires in the very inlet end of the dewatering space. This results in an advantage with respect to capacity, in a manner such that the dewatering can begin earlier in the dewatering space. The conventional sealing blades form a doorstep in the dewatering space at the ends of the sealing blades, and the clearance of the space where the pulp suspension is conveyed in the dewatering space is increased by several millimeters at the ends of the sealing blades, which influences the formation and dewatering process. In accordance with the solution according to the present invention, a more even and gentle transition can be achieved, where the pulp suspension is passing by the ends of the sealing elements, which results in a better formation and dewatering of the pulp suspension. Besides, the grammage becomes lower, thanks to a thinner pulp thickness in this area between the dewatering tables at the inlet end of the dewatering space, which is very desirable when it comes to the properties of the twin-wire press.

The sealing elements may have a certain elasticity/flexibility, but return to their original shape when the load decreases. Thus, deformation of the sealing elements does not become permanent. Owing to that, the respective sealing element can be designed as a wedge-shaped elastic body, the life time of the sealing elements can be extended and the wear may even be decreased. By a suitable material choice, a desired rigidity can be provided for the sealing elements according to the present invention. Consequently, the prior requirements with respect to alignment of the conventional thin sealing blades, according to the prior art, may be eliminated. In addition, this facilitates production in various materials, even materials other than metal, for the sealing members. The sealing elements according to the present invention facilitate both a more cost-efficient production, assembly and exchange than the case of the traditionally used sealing blades.

Each sealing element has a wedge-shaped cross section. In that respect, each sealing element presents a first side, that delimits a part of the passage for the fiber suspension, and a second side that extends with an acute angle towards the first side and that is arranged to at least in part be sealingly arranged against the associated wire. The other design of the sealing elements may be varied for adaptation to various pulp environments and geometries of other twin-wire p

According to an embodiment of the present invention, it is possible to arrange the sealing elements such that their position towards the wire guiding members can be adjusted in the longitudinal direction of the twin-wire press. According to yet another embodiment of the present invention, the wire guiding members can be adjustably arranged in the vertical direction towards the sealing elements. According to another embodiment of the present invention, the wire guiding members can be integrated with the perforated dewatering elements that are arranged against the respective wire in the dewatering space. By the wedge-shape of the sealing elements, the distances of the dewatering space may in that respect vary by horizontal movement of the sealing elements according to another embodiment hereof, in a direction towards and away from the wire guiding members, respectively, when they are integrated with the perforated dewatering elements. According to yet another embodiment of the present invention, the wire guiding members can comprise perforated dewatering elements, at least in connection towards the inlet end of the dewatering space, such that dewatering can be started immediately at the entrance of the pulp suspension between the dewatering tables and immediately after the pulp suspension has passed by the sealing members, that is at the position where the respective wire leaves the end of the sealing members at the abutment against the respective wire guiding member.

The wire guiding members, respectively, can be provided with a wear element on their surfaces against the respective wires. The wear elements can be designed such that they are an exchangeable wear part on the wire guiding member. The wear element is suitably made of a polymer. In that respect an increase of the lifetime for wire guiding members to a twin-wire press can be achieved. The respective sealing elements associated with respective wire guiding member suitably have a shape such that they are at least partially form-fitted for each other, i.e. a respective geometric form that is adapted for each other, along a portion where they abut against each other.

The sealing elements may substantially be made of a polymer, such as e.g. polyethylene, which has proved to quite perfectly resist wear in various pulp environments and to a very large extent resist wear of carbides that are formed from fillers. In that respect, an increase of the lifetime of the sealing members for a twin-wire press can be provided.

The wire guiding members need not necessarily show any elasticity. The wear element of the wire guiding members may also be produced from a very hard material, such as e.g. a ceramic material. Thus, according to one embodiment of the present invention, form one starting point, the wire guiding members can be said to control the shape of the sealing elements. The wire guiding members need not be elastic, but the sealing elements may suitably be elastic.

It is also possible that the sealing elements and the wire guiding members can be designed with a core of metal having a surface treatment, such as an outer portion of a plastic material.

Additional preferred features, advantages and preferred embodiments according to the invention are evident from the dependent claims, and also from the following description of embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail with reference to the following detailed description which, in turn, refers to the accompanying drawings, without restricted interpretation of the invention thereof, in which:

FIG. 1 is a side, elevational, partial, cross-sectional schematic view of an inlet section of a conventional twin-wire press;

FIG. 2A is a side, elevational, partial, cross-sectional schematic view of an inlet section of a twin-wire press according to an embodiment of the present invention;

FIG. 2B is a side, elevational, partial, cross-sectional schematic view of an inlet section of a twin-wire press according to another embodiment of the present invention; and

FIG. 2C is a side, elevational, cross-sectional schematic view of a twin-wire press, according to another embodiment of the present invention, which can comprise any of the embodiments shown in FIGS. 2A and 2B.

DETAILED DESCRIPTION

To make it clear, a conventional twin-wire press is first described with reference to FIG. 1, that schematically shows a part of an inlet section 3 of the conventional twin-wire press 2, to be precise a section at an inlet end 4 of a dewatering space 6 in the area at and around an inlet box 8. The fiber suspension that is to be dewatered is supplied from the inlet box 8 to the dewatering space 6 delimited between an endless lower wire 10 and an endless upper wire 12 during displacement of the wires, 10 and 12. Perforated dewatering elements, 14 and 16, abut against the wires outside the dewatering space. Such perforated dewatering elements are used along the whole length L1 of the dewatering space for removal of filtrate from the dewatering space. The wire guiding members, 18 and 20, shown in FIG. 1, that are arranged at the inlet section 3 of the twin-wire press, are made, respectively, of curved sheet metal against which the respective wire runs, and replaces those rolls that are conventionally used at an inlet section of a twin-wire press. The wire guiding members, 18 and 20, have an oblique surface, 18′ and 20′, against which each respective wire runs, having a longitudinal extension L2 which forms an acute angle towards the longitudinal extension L1 of the dewatering space. Thus, an upper wire guiding member 20 is arranged to guide the upper wire obliquely downwards towards the inlet end of the dewatering space and a lower wire guiding member 18 is arranged to guide the lower wire obliquely upwards towards the inlet end of the dewatering space. In that way a tapering space 21 is formed between the upper and lower wire guiding members. Filtrate flows through the wires, 10 and 12, from the dewatering space and are colleted in outlet boxes, 22 and 24. The lower outlet box 22, arranged in a lower dewatering table, collects filtrate that flows from the dewatering space through the lower wire 10 and lower dewatering elements, while the upper outlet box 24, arranged in an upper dewatering table, collects filtrate that flows from the dewatering space through the upper wire 12 and upper dewatering elements. Furthermore, the conventional twin-wire press comprises perforated dewatering elements, 14 16, arranged in direct connection to sealing blades, 26 and 28, extending from the inlet box 8, whose free ends abut against a respective inside, 30 and 32, of the wires, 10 and 12, in the dewatering space.

In the following discussion, the twin-wire press according to the present invention is described, with reference to the embodiments shown in FIGS. 2A-C. Corresponding conventional features and components are denoted with the same reference numerals for the embodiments according to the invention shown in FIGS. 2A-C as for the inlet section of the conventional twin-wire press shown in FIG. 1.

FIGS. 2A-B show an inlet section 51 of a twin-wire press 50 according to the present invention, that like the twin-wire press 2 in FIG. 1 shows a dewatering space 6, an inlet box 8, an endless lower wire 10, an endless upper wire 12, perforated dewatering elements, 14 and 16, wire guiding members, 18 and 20, a tapering space 21 and outlet boxes, 22 and 24. The dewatering space 6 has an inlet end 52.

As is evident from the embodiments in FIGS. 2A and B according to the present invention, the twin-wire press 50 comprises sealing members, 53 and 54, in the shape of a respective sealing element, 53′ and 53″, and 54′ and 54″, arranged on each side at an inlet end 52 of the dewatering space 6 in direct connection to the inlet box 8. The sealing elements, 53′ and 53″, and 54′ and 54″, extend along substantially the entire width of the twin-wire press (perpendicular the plane of the paper in FIGS. 2A and 2B). An upper sealing element, 53″ and 54″, abuts in the tapering space 21 between the upper and lower wire guiding members, 18 and 20, sealingly against the upper wire 12. A lower sealing element, 53′ and 54′, abuts in the tapering space between the upper and lower wire guiding members, 18 and 20, sealingly against the lower wire 10. The upper and lower sealing elements, 53′ and 53″, and 54′ and 54″, delimit between each other a passage 55 for the fiber suspension, that flows to the dewatering space 6 from the inlet box 8. In accordance with an embodiment of the present invention, the respective sealing element, 53′ and 53″, and 54′ and 54″, abut substantially only sealingly against the respective wire guiding member, 18 and 20. In accordance with the previous conventional sealing blades, the abutment was also against the dewatering elements, 14 and 16 (see FIG. 1).

The respective sealing element, 53′, and 53″, and 54′ and 54″, has a wedge-shaped cross-section, as seen in the longitudinal direction L1 of the twin-wire press, as is evident from FIGS. 2A and 2B, which show a first side 56 that delimits a portion of passage 55, and a second side 60 facing from and opposite the first side and that passage. Furthermore, the respective sealing elements show a third side 61 that is arranged to the inlet box 8. The respective wire runs against the oblique surface, 18′ and 20′, of the respective wire guiding members, 18 and 20. According to the present invention, a seal is achieved by means of the respective oblique surface on the second side 60 of the sealing elements, 53 and 54, against the respective oblique surface, 18′ and 20′, of the wire guiding members. Consequently, with the present invention, a gentle and even transition between the sealing surface and the dewatering space is achieved in the position where the respective wire, 10 and 12, leaves the end 58 of the sealing element.

According to the present invention, as is evident from FIG. 2A, the first side 56 and the second side 60 form a tongue-shaped, tapering, sharp portion 57 where the sides are met at the respective free end 58 of the sealing element in abutment against the inside of the respective wire. This is one example of how the respective sealing element with associated respective wire guiding member suitably may have a design that is at least partially form-fitted with each other, i.e. a respective geometric shape that is adapted after each other, along an oblique portion where they abut against each other.

Returning to the common description of the two embodiments shown in FIGS. 2A and 2B, the sealing elements, 53′ and 53″, and 54′ and 54″, may comprise a recess 62 such as a groove or the like, that can be installed on a rail or a similar attachment device on the inlet box. The sealing elements can be arranged such that their position against the wire guiding members can be adjusted in the horizontal direction in the longitudinal direction L1 of the twin-wire press, which is a preferred embodiment in particular for the sealing element 54 according to FIG. 2B. The wire guiding members, 18 and 20, can be adjustably arranged in a vertical direction V1 against the sealing elements, 53′ and 53″, and 54′ and 54″.

A substantially similar distance H2 between the first sides 56 of the respective the sealing elements, 53 and 54, that form the passage 55 for the pulp suspension from the inlet box, is achieved in accordance with the present invention, like distance H1 between the upper and lower wires, 10 and 12, at the very inlet end of the dewatering space 6. In accordance with the solution of the present invention, a more even and gentle transition can be provided, where the pulp suspension is passing by the end 58 of the sealing elements.

Said sealing elements, 53′ and 53″, and 54′ and 54″, are suitably made of a polymer, partially or completely. A polymer may for instance be polyethylene.

In the embodiments shown in FIGS. 2A-B, the wire guiding members, 18 and 20, are provided with a wear element, 64 and 66, in the form of an exchangeable wear part, on the oblique surfaces, 18′ and 20′, against each wire 10, 12. The wear element may e.g. be a ceramic material or a polymer. The wear element is e.g. polyethylene. The wear element may be designed as a separate exchangeable part that can be pushed on or off by means of a slot, or alternatively a rail, on the body of the wire guiding member.

The wire guiding members, 18 and 20, and the sealing elements, 53′ and 53″, and 54′ and 54″, respectively, can also comprise a core of metal, surrounded by a wear element, e.g. a polymer.

According to an embodiment of the present invention (not shown) the wire guiding members, 18 and 20, can be integrated with the perforated dewatering elements, 14 and 16, i.e. can be arranged connected in one piece, for abutment against the respective wire in the dewatering space. The distance H1 of the dewatering space may in that respect, according to an embodiment hereof, be varied by horizontal movement of the sealing elements, in the longitudinal direction L1 of the twin-wire press, in a direction towards and from, respectively, the wire guiding members when they are integrated, i.e. be formed in one piece, with the perforated dewatering elements. The wire guiding members may at least partially comprise perforated dewatering elements (not shown) adjacent to the dewatering space such that dewatering can immediately be started already at the inlet end of the dewatering space, at the position where respective wire leaves the respective end 58 of the sealing elements.

FIG. 2C shows an exemplifying performance of the whole twin-wire press 50 that may comprise the inlet section 51 shown in the embodiments according to FIGS. 2A and 2B according to the present invention. The twin-wire press 50 comprises three lower rolls, more specifically a drive roll 100, a guide roll 102 and a stretch roll 104. The above mentioned endless lower wire 10 runs in a path around the lower rolls, 100, 102, and 104. In a corresponding way, the above mentioned upper endless wire 12 runs in a path around three upper rolls, specifically a drive roll 106, a guide roll 108 and a stretch roll 110. The above mentioned upper outlet box 24 in the upper dewatering table, that supports the upper wire 12, and the above mentioned lower outlet box 22 in the lower dewatering table, that supports the lower wire 10, forms the dewatering space 6 between the wires, 10 and 12. The twin-wire press shown in FIG. 2C comprises the sealing members, 53 and 54, (not shown in FIG. 2C) in accordance with the present invention, which have been described above with reference to FIG. 2A and FIG. 2B, respectively. The twin-wire press comprises an ordinary roll arrangement 112 according to the state of the art.

During operation of the twin-wire press according to FIGS. 2A-C, movement of the wires, 10 and 12, is carried out by rotation of the rolls, 100 through 110. The fiber suspension, that is to be dewatered, is fed to the oblong dewatering space 6 by means of the inlet box 8 at the inlet end 52 thereof. The fiber suspension is dewatered in the dewatering space 6 during movement of the wires, such that a filtrate flow is created from the dewatering space 6 through the wires, 10 and 12, and the perforated dewatering elements, 14 and 16. The filtrate that flows from the dewatering space through the wires is collected in the outlet boxes, 22 and 24.

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1-10. (canceled)

11. A twin-wire press for dewatering a fiber suspension comprising an endless lower wire and an endless upper wire defining an elongated dewatering space therebetween having an inlet end and an outlet end for dewatering said fiber suspension during simultaneous displacement of said endless upper and lower wires, an inlet box for supplying said fiber suspension to said inlet end of said elongated dewatering space, upper and lower perforated dewatering elements disposed against the sides of said endless upper and lower wires outside of said elongated dewatering space, an upper outlet box for collection of filtrate flowing from said elongated dewatering space through said upper wire and said upper perforated dewatering element, a lower outlet box for collection of filtrate flowing from said elongated dewatering space through said lower wire and said lower perforated dewatering element, an upper wire guiding member arranged to guide said endless upper wire obliquely downwardly towards said inlet end of said elongated dewatering space, a lower wire guiding member arranged to guide said endless lower wire obliquely upwardly towards said inlet end of said elongated dewatering space, whereby a tapering space is formed between said upper and lower wire guiding members, and upper and lower wedge-shaped sealing members extending from said inlet box towards said inlet end of said elongated dewatering space for creating a seal in said tapering space between said endless upper and lower wires and said fiber suspension entering said elongated dewatering space, said upper and lower wedge-shaped sealing members defining a passage therebetween for said fiber suspension flowing to said elongated dewatering space from said inlet box, each of said wedge-shaped upper and lower sealing elements including an inner surface defining part of said passage for said fiber suspension and an outer surface extending at an acute angle towards said inner surface, at least part of said wedge-shaped upper and lower sealing elements sealingly disposed against its respective upper and lower wire, the distance between said inner surfaces of said upper and lower wedge-shaped sealing elements forming said passage for said fiber suspension being substantially equal to the distance between said upper and lower wires at the inlet end of said elongated dewatering space.

12. The twin-wire press of claim 11 wherein said at least part of each of said upper and lower wedge-shaped sealing elements is sealingly disposed against its respective upper and lower wire only at the location of said respective upper and lower wire guiding member corresponding thereto.

13. The twin-wire press of claim 11 wherein said inner and outer surfaces of each of said upper and lower wedge-shaped sealing elements tapers into a narrow, tongue-shaped portion towards a free end of said respective upper and lower wedge-shaped sealing elements in abutment against the inner surfaces of said upper and lower wires, respectively.

14. The twin-wire press of claim 11 wherein each of said upper and lower wedge-shaped sealing elements and said corresponding upper and lower wire guiding members includes adjacent oblique portions abutting against each other with said upper and lower endless wires therebetween.

15. The twin-wire press of claim 11 wherein said upper and lower wedge-shaped sealing elements comprise a polymer.

16. The twin-wire press of claim 11 wherein each of said upper and lower wedge-shaped sealing elements is horizontally adjustable against each of said respective upper and lower wire guiding members in the longitudinal direction of said twin-wire press.

17. The twin-wire press of claim 11 wherein said upper and lower wire guiding members are vertically adjustable against said upper and lower wedge-shaped sealing elements.

18. The twin-wire press of claim 11 wherein said upper and lower wire guiding members include wear element portions disposed against said upper and lower endless wires respectively.

19. The twin-wire press of claim 11 wherein said upper and lower wire guiding members are integrally attached to said upper and lower perforated dewatering elements.

20. The twin-wire press of claim 11 wherein said upper and lower wire guiding members are integral with said upper and lower perforated dewatering elements, respectively.