AN APPARATUS FOR PROCESSING PULP

Technical Field

The present invention relates to sealing arrangements, for example, for use in sealing between a rotatable drum and a stationary end casing member of an apparatus for dewatering pulp, and to pressure means for a sealing

arrangements, for example, for use in sealing between a rotatable drum and a stationary end casing member of an apparatus for dewatering pulp.

Background of the Invention

Fibre lines producing cellulose-based products may comprise some type of washing equipment for separating the liquor of the cooking from the pulp. Later on in the process, washing equipment is also provided to separate bleaching liquors after the bleaching steps. There is a plurality of different types of washing equipment operating according to different principles.

When producing cellulose-based products, a roll press is frequently used for washing and/or dewatering the cellulose-based pulp. The roll press comprises two co-operating and counter-rotating press rolls, each having a permeable outer surface, a so called mantle surface, whereby the outer surface is permeable to liquid pressed out of the pulp. The pulp is deposited on the permeable outer surface and pressed in the roll nip, or the press nip, between the press rolls, whereby liq- uid is pressed out of the pulp. The roll press may also include one or more washing zones prior to the press nip.

Another known washing equipment is the drum washer, where the cellulose-containing pulp is deposited and dewatered on a single rotating filter drum, which has a permeable outer surface, after the addition of washing liquid, which displaces the liquor remaining on the pulp web after the preceding process step, for example a cooking step or bleaching step. The static pressure causes the contaminated liquid, called filtrate, to pass through the outer surface permeable to liquid. A further development of the original drum washer is the pressurized displacement washer, where the filtrate, under overpressure, is forced to pass through the permeable outer surface.

In general, around at least a portion of the circumference of the permeable outer surface of the drum or press roll, an axially extending and circumferential gap or space may be provided which is sealed off from the atmosphere to produce an overpressure in order to force the filtrate from the pulp, which is located on the outer surface in said gap, to pass through the permeable outer surface. By means of the sealed-off gap, the dewatering of the pulp is enhanced. Sealing arrangements including a plurality of components are generally required to seal off such a gap.

WO2010/036193 discloses sealing arrangements for sealing between a movable side casing member and the outer surface of a rotatable press roll, between the movable side casing member and an end casing member, and between the movable side casing member and a central casing member. Further, sealing arrangements for sealing between each end of a rotatable press roll and the end casing member may also be required.

WO 2012/134373 discloses sealing arrangement for sealing between rotatable drums and respective end casing members. The sealing arrangements comprises an inflatable and stiff tube arranged in a groove for providing pressure when inflated to thereby force a sealing member in a direction towards a drum to bear against a portion of and end surface of the drum.

In these prior art solutions, the inflatable tube is shaped and arranged to expand in only the direction towards the sealing member, that is, the tube has different stiffness in different directions. Accordingly, it is very important that the tube is correctly and accurately oriented in the groove. This makes it cumbersome to install a tube and/or replace a worn out tube with a new one. When installing a new tube, it is manually pushed into the groove from one open end of the groove, which groove is long, narrow and curved. For a correct and proper functioning of the tube and sealing arrangement, it is crucial that the tube is installed into the groove in the correct orientation such that the expansion of the tube when it is inflated takes place in the right direction, i.e. towards the movable sealing member to put pressure on the sealing element. During the installation, when the tube is pushed into the groove, the tube tends to turn in the groove such that it is not correctly oriented in the groove. Furthermore, the length of the inflatable tube is exactly adapted to the extension or length of the circumferential groove for a certain apparatus in order to provide the required pressure on the sealing member along its entire length. Therefore, it is necessary to hold a number of different tube lengths in stock to be able to replace a worn out tube quickly in order to avoid unnecessary long production interruptions. Thus, there is a need within the art for improved sealing arrangements for use in, for example, sealing between a rotatable drum and a stationary end casing member in an apparatus for dewatering pulp, especially cellulose-containing pulp.

Summary of the Invention

An object of the present invention is thus to provide improved sealing arrangements, for example, for use in sealing between a rotatable drum and a stationary end casing member of an apparatus for dewatering pulp.

A further object of the present invention is to provide improved pressure means for a sealing arrangement, for example, for use in sealing between a rotatable drum and a stationary end casing member of an apparatus for

dewatering pulp.

The above-mentioned objects of the present invention are attained by providing a pressure device for a sealing arrangement, and a sealing arrangement for sealing, for example, between a first drum and an end casing member included in an apparatus for processing pulp, especially cellulose-containing pulp, the first drum being rotatable about an axis of rotation in relation to the end casing member and the sealing arrangement, and the first drum being provided with a permeable outer surface which axially extends between a first end and a second end of the first drum, and at least at the first end the first drum is provided with an end surface.

According to a first aspect of the present invention, there is provided a pressure device for a sealing arrangement including a movable sealing element for mounting in a holder comprising an extended groove. The pressure device comprises an elastic tube, which is expandable by a pressurizing fluid and has a first cross-section area, and the elastic tube has a rotational symmetric cross- section area, a nipple element having a nipple arranged for connection to a pressurizing fluid supply, and at least one collar arranged to connect the

pressurized elastic tube to the nipple element and to fluid-tightly and firmly lock the pressurized elastic tube to the nipple element. By locking the elastic tube firmly to nipple element, it is meant that the elastic tube when locked by the collar will not more relative to the nipple element. When pressurized, the elastic tube acts on the movable sealing element, the movable sealing element being arranged to fit into the groove and is provided with a first sealing surface for sealing against a surface. An inner surface of the movable sealing element is in contact with the elastic tube and when the elastic tube is pressurized, the movable sealing element is pressed in an outward direction by the expanding elastic tube to thereby bear against a surface to provide a seal.

The sealing member may be rigid, and may, for example, be made of a polymer material.

The rotational symmetric elastic tube may be made of a flexible material, e.g. a polymer material.

According to a second aspect of the present invention, there is provided a sealing arrangement including a movable sealing element and a holder comprising an extended groove in which the movable sealing element is mounted, wherein the sealing arrangement comprises a pressure device according to a first aspect of the present invention.

According to a third aspect of the present invention, there is provided an apparatus for processing pulp, comprising at least one first drum rotatable about an axis of rotation and provided with an outer surface permeable to liquid, the outer surface axially extending between a first end and a second end of the first drum, the apparatus is adapted to receive the pulp on the outer surface of the first drum and to process the pulp situated on the outer surface while rotating the first drum, and the apparatus is adapted to process the pulp by at least dewatering the pulp, the first drum being rotatably mounted to two end casing members, at least at the first end the first drum being provided with an end surface, and at least one of the end casing members holds a sealing arrangement according to the second aspect of the present invention, and including a pressure device according to the first aspect of the present invention, for sealing between the first drum and the respective end casing member, the first drum being rotatable in relation to the sealing arrangement.

The holder may be in the form of a circumferentially extending holder, and may e.g. comprise a circumferentially extending groove which may hold the pres- sure device and the sealing element. The sealing element may be elongated in the circumferential direction. The end surface may be formed by a solid circular plate, or by an end ring, or any other structure of the first drum. The end surface may be in the form of an annular surface surrounding the axis of rotation or an annular surface portion surrounding the axis of rotation. The annular surface or surface portion may be formed by an end ring.

According to another advantageous embodiment of the apparatus according to the present invention, at least one of the end casing members holds a second sealing arrangement for sealing between the second drum and the respective end casing member, the second drum being rotatable in relation to the second sealing arrangement, and the second sealing arrangement comprises the features of the first and/or second aspect of the present invention, or the features of any of the embodiments of the sealing arrangement discussed herein.

The features and embodiments of the sealing arrangement and the apparatus, respectively, discussed herein may be combined in various possible ways providing further advantageous embodiments.

Further advantageous embodiments of the sealing arrangement and the apparatus, respectively, according to the present invention and further advantages with the present invention emerge from the detailed description of embodiments.

Brief Description of the Drawings

The present invention will now be described, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, in which:

Fig. 1 is a schematic view of the pressure device according to an embodiment of the present invention;

Fig 2 is a schematic top view of the of the pressure device of Fig. 1 provided in a holder;

Fig 3 is a schematic cross-sectional view of the sealing arrangement according to an embodiment of the present invention illustrating the pressure device provided in the holder shown in

Fig. 2 and a sealing element;

Fig 4 is a schematic view of a collar of the pressure device

according to an embodiment of the present invention;

Fig 5 is schematic cross-sectional view of the collar of Fig. 5;

Fig 6 is a schematic view of a nipple element of the pressure device according to an embodiment of the present invention;

Fig 7 is schematic side view of the nipple element of Fig. 6; Fig. 8 is schematic view of a tube of the pressure device of the

pressure device according to an embodiment of the present invention;

Fig. 9 is schematic cross-sectional view of the tube of Fig. 8;

Fig. 10 is a schematic view of a nipple element of the pressure device according to an embodiment of the present invention;

Fig. 1 1 is schematic view of an end-plug of the pressure device

according to an embodiment the present invention,

Fig. 12 is a schematic side view of an apparatus provided with an em- bodiment of the sealing arrangement according to the present invention; and

Fig. 13 is a schematic top view of the of the vat segments of Fig. 12.

Detailed Description of Embodiments of the present invention

With reference to Figs. 1 - 1 1 , a pressure device according to

embodiments of the present invention will be discussed. The pressure device 10 for a sealing arrangement 50, as shown e.g. in Fig. 3, comprises an elastic tube 20, which is expandable by a pressurizing fluid and has a first cross-section area 22. The sealing arrangement 50 included a movable sealing element 70 and a holder 55 comprising an extended groove 60 in which the holder 55 is mounted. The elastic tube 20 has rotational symmetric cross-section area 22. Further, the pressure device 10 comprises at least one collar 30 having an inner cross-section area 32 corresponding to the first cross-section area 22 of the elastic tube 20. The pressure device 10 further comprises a nipple element 40, 80.

The collar 30 is arranged to connect the elastic tube 20 to the nipple element 40 according to a first embodiment, or the nipple element 80 according to a second embodiment shown in Fig. 10, and to fluid-tightly and firmly lock the elastic tube 20 to the nipple element 40. Firmly locking the elastic tube to the nipple element means that the elastic tube is not able move relative the nipple element.

The nipple element 40, 80 is provided with a nipple 44, 84 arranged for connection to a pressurizing fluid supply, wherein the elastic tube can be pressurized when connected to the fluid supply via the nipple element. When pressurized, the elastic tube 20 acts on the movable sealing element 70 such that the movable sealing element 70 is pressed in an outward direction by the expanding elastic tube 20 to bear against a surface 71 to provide a seal, for example, against an end surface of a rotatable drum.

According to embodiments, e.g. as shown in Fig. 5, an inner surface 35 of the collar 30 is provided with a structure, for example, a thread 34. The structure 34 corresponds to a structure 46, e.g. a thread 46, provided on an outer surface of an extension part 42 of the nipple element 40 arranged to fit into the elastic tube 20.

The extension part 42 is arranged to conduct pressurizing fluid into the elastic tube 20, wherein the collar 30 can be threaded or screwed over a part of the elastic tube 20 enclosing the extension part 42 to fluid-tightly and firmly lock the elastic tube 20 to the nipple element 40 such that when locked, the elastic tube 20 will not move in relation to the nipple element 40.

In Fig. 1 , the collar 30 is shown in a state where it is threaded to lock the tube 20 to the nipple element 40.

In embodiments of the present invention, as shown in Fig. 6, the thread 46 of the outer surface of the extension part 42 of the nipple element 40 is closed at an end adjacent to the nipple 44.

According to a further embodiment of the nipple element 80 shown in Fig.

10, the nipple element 80 is arranged with a first extension part 82 provided with a thread 86 and a second extension part 83 provided with a thread 85, wherein the first and second extension part 82, 83 are arranged to fit into an elastic tube 20. As illustrated, the nipple element 80 is arranged with T-like shape.

According to embodiments of the present invention, the groove 60 of the holder 55 is square shaped and an outer surface 36 of the collar is square shaped and arranged to fit into the groove 60. However, in other embodiments of the present invention, the outer surface of the collar is circular, rounded or elliptically shaped, and arranged to fit into the groove

According to embodiments of the present invention, as shown in Fig. 1 1 , the pressure device may also comprise an end-plug 90 for fluid-tightly terminate an end of the tube 20. In order to provide sufficient fluid-tightness and to allow an easier introduction of the end-plug into the tube 20, the end-plug is provided with a thread 96, which may be closed at the end part. The end-plug may be tightly locked or connected to the tube by a collar 30.

Fig. 12 shows an embodiment of an apparatus for dewatering cellulose- containing pulp provided with an embodiment of the sealing arrangement and pressure device according to the present invention. The apparatus may also be arranged to wash the pulp. The apparatus may have a substantially symmetric configuration with regard to a symmetry plane 101 , and in Fig. 12, the left side of the apparatus, i.e. to the left of the symmetry plane 101 , illustrates the apparatus in an opened position, whereas the right side of the apparatus, i.e. to the right of the symmetry plane 101 , illustrates the apparatus in a closed and operating position. The apparatus may comprise a first rotatable drum 102 or press roll and a second rotatable drum 104 or press roll, each drum 102, 104 having a permeable outer surface 106, 108. Each permeable outer surface 106, 108 extends axially between a first end and a second end of the respective drum 102, 104. The first drum 102 is rotatable about a first axis of rotation, and the second drum 104 is rotatable about a second axis of rotation. The drums 102, 104 may comprise a plurality of filtrate channels 1 10 radially inwards of the outer surface 106, 108 to lead evacuated filtrate away. The two drums 102, 104 define a press nip 1 12 between them, in which press nip the pulp is pressed, and are arranged to rotate in opposite directions. The apparatus may be arranged to feed the pulp through the press nip 1 12 in a substantially vertical direction from below upwards, however, the pulp can be fed through the press nip 1 12 in other directions.

The apparatus may comprise a casing which includes a vat 1 14, 1 16, 1 18, in which the drums 102, 104 are installed, the vat 1 14, 1 16, 1 18 partly enclosing the outer surface 106, 108 of each drum 102, 104, whereby a space or gap 124, 125 for each drum 102, 104 is defined, limited by the vat 1 14, 1 16, 1 18 and the outer surface 106, 108 of the respective drum 102, 104. The vat 1 14, 1 16, 1 18 may be built up of a first side vat segment 1 14 which partly encloses the outer surface 106 of the first drum 102, a second side vat segment 1 16 which partly en- closes the outer surface 108 of the second drum 104, and a central vat segment 1 18 partly enclosing the outer surface 106, 108 of the drums 102, 104 between the press nip 1 12 and the side vat segments 1 14, 1 16. The central vat segment 1 18 may be movable in a substantially vertical direction for providing additional accessibility to the region in proximity to the press nip 1 12. In Fig. 12, on the left side of the apparatus, the central vat segment 1 18 is shown in an inoperative opened position, whereas on the right side of the apparatus, the central vat segment 1 18 is shown in an operative closed position.

As mentioned above, a gap 124, 125 may be formed between the vat 1 14, 1 16, 1 18 and the outer surface 106, 108 of the drums 102, 104. In Fig. 12, only the right side of the apparatus illustrated the apparatus in a closed and operating position, and thus, only the gap 124 with regard to the second drum 104 and the vat 1 16, 1 18 is shown, whereas the gap 125 with regard to the first drum 102 and the vat 1 14, 1 18 is not present in Fig. 12. However, a corresponding gap 125 with re- gard to the first drum 102 is illustrated by a broken line in Fig. 12. When the left side of the apparatus is in a corresponding closed and operating position, a gap is provided between the first drum 102 and the vat 1 14, 1 18.

The casing may comprise a first side casing member 1 15 which extends between the ends of the first drum 102 and to which the first side vat segment 1 14 is mounted, and a second side casing member 1 17 which extends between the ends of the second drum 104 and to which the second side vat segment 1 16 is mounted. The side casing members 1 15, 1 17, together with their side vat segments 1 14, 1 16, may be pivotable about a pivot axis 121 , 123, and movable between a closed position and an opened position for providing access to the drums 102, 104. In Fig. 12, on the left side of the apparatus, the first side casing member 1 15 is in the opened position, whereby access to the drum 102 is provided, whereas on the right side of the apparatus, the second side casing member 1 17 is in the closed position. Alternatively, only one of the side casing members could be movable, whereas the other could be stationary, or both side casing members could be stationary. The movable side casing member could also be movable in other ways than by pivoting about the respective pivot axis 121 , 123.

Further, the casing may include a central casing member 140, in the form of a stationary base unit 140 positioned substantially below the first and second drums 102, 104, a stationary first end casing member 210 in the form of a first ga- ble, and a stationary second end casing member 212 in the form of a second gable (the end casing members 210, 212 being shown in Fig. 13). The drums 102, 104 may be rotatably mounted to the end casing members 210, 212, and thus be rotatable in relation to the end casing members 210, 212. The central casing member 140 may be mounted to the end casing members 210, 212. Each side casing member 1 15, 1 17 may be pivotally attached to the central casing member 140, and each side casing member 1 15, 1 17 may also be connected to the central casing member 140 via a respective hydraulic cylinder 178, 179 for controlling the movement of the respective side casing member 1 15, 1 17. The central vat seg- ment 1 18 may be mounted to the central casing member 140.

Sealing arrangements may be provided between each movable side casing member 1 15, 1 17 and the central casing member 140, and between each movable side casing member 1 15, 1 17 and the end casing members 210, 212. Further, axial sealing units 180, 182 may be mounted to each side casing member 1 15, 1 17, each axial sealing unit 180, 182 extending along to the longitudinal extension of the respective drum 102, 104 and is adapted to abut the outer surface 106, 108 of the drum 102, 104 when the side casing member 1 15, 1 17 is in its closed position. The sealing arrangements and the axial sealing units 180, 182 are adapted to seal off the gap 124, 125 from the external surroundings, i.e. the at- mosphere, at the position where the pulp is distributed to the gap 124, 125. Each axial sealing unit 180, 182 may be in the form of a scraper. Thus, by way of the above-mentioned sealing arrangements and axial sealing units 180, 182, the gap 124, 125 and the surfaces defining the gap 124, 125 are sealed off from the atmosphere.

The apparatus may comprise a first pulp distribution device 126 for distributing pulp on the first drum 102 and a second pulp distribution device 128 for distributing pulp on the second drum 104. Pulp to the distribution devices 126, 128 may be supplied in various ways known to the skilled person. The pulp distribution devices 126, 128 may be arranged to distribute pulp to the gap 124, 125 along the whole axial length of each drum 102, 104. The pulp distributed on the outer surface 106, 108 of the drum 102, 104 may form a mat on the drums 102, 104. From the pulp distribution devices 126, 128 to the press nip 1 12, the pulp is fed in the gap 124, 125 in the direction of rotation Ri, R2 of the drums 102, 104 while being dewatered, or dewatered and washed.

Fig. 13 shows the central vat segment 1 18 in the apparatus as viewed from above with the drums excluded. The apparatus may rest on the ground via four legs 186, 187, 188, 189 (only two legs are shown in Fig. 12). In Fig. 13, the end casing members 210, 212 of the casing are schematically shown. However, a pulp dewatering apparatus provided with the sealing arrangement according to the present invention may have a casing without movable side casing members.

According to another advantageous embodiments of the apparatus according to the present invention, at least one of the end casing members holds a second sealing arrangement for sealing between the second drum and the respective end casing member, the second drum being rotatable in relation to the second sealing arrangement, and the second sealing arrangement comprises the features of the first and/or second aspect of the present invention, or the features of any of the embodiments of the sealing arrangement discussed herein.

The features and embodiments of the sealing arrangement and the apparatus, respectively, discussed herein may be combined in various possible ways providing further advantageous embodiments.

Hence, the invention shall not be considered limited to the embodiments illustrated, but can be modified and altered in many ways by one skilled in the art, without departing from the scope of the appended claims.