Abstract: The object of the invention is an apparatus and a method for improving the detachment of paper (1) from the cylinder of a paper machine in a drying section implemented with a single wire transfer, which drying section comprises means for heating the paper on the drying cylinder (3) and for transporting it onwards on the wire (2) via a hitch roll (8) to the next drying cylinder such that the paper together with the wire in the section between the cylinders is sucked against the wire by means of low pressure. What is essential to the invention is that in order to improve the detachment of the paper (1) an apparatus is installed on the opposite side of the drying wire (2) at the detachment point (7), which apparatus comprises a nozzle (14), with which an air jet (11) is blown against the direction of travel (15) of the drying wire, and a carrying surface (9) such that the air jet (11) ejects secondary air (17) along with it causing an air flow (18) between the planar carrying surface (9) and the drying wire (2).

Abstract: The invention comprises a method and an arrangement in a paper machine or the like close to a moving web (29) usually supported against a wire (1), and a paper machine including such an arrangement, and a sealing device having several such arrangements (100). According to the invention, a movable sealing (5) is arranged in the drying section of a paper machine, between two regions (3, 4) with different pressures. Certain air amounts (V1, V2) are supplied to and/or discharged from each side of the sealing (5) in order to create certain pressures in said regions. Air can move between said regions only through certain paths. In normal operating situations the seal (5) according to the invention is automatically adjusted to the desired position in relation to the web.

Abstract: The invention relates to an arrangement and a method for sealing of a pocket space between drying cylinders (2, 3) in a paper machine or similar. In the method for sealing of the pocket space: a wire (5) is moved supported by the first and the second cylinder (2, 3, 4), a gap between the pocket space (15) and the space outside (24) it is sealed by a runnability component (6), which comprises at least a sealing surface (19, 22) and a blow nozzle (21) provided with a nozzle slot (26) of a size of 0.5-3.5 mm and elongated in the cross direction, the sealing surface (19, 22) is kept at a distance of 5-15 mm from the moving wire (5), air is blown with the blow nozzle (21) from a blow point (27) and along the sealing surface (22) towards a sealing point (16) and further via the sealing point (16) away (24) from the pocket space. The invention comprises also a runnability component (6) and a method for manufacturing the same.

Abstract: A throughdrying process and system for the manufacture of a tissue web conveys a fibrous web of cellulose fibers through a throughair drying station that includes one or more throughair dryers. The throughair drying station is supplied with a heated drying medium from a source. After drying the web, the drying medium is conducted away from the throughair drying station as moisture laden exhaust air that is collected, dried, and at least partially recirculated back to the throughair drying station as a supplement to the source of heated drying medium, thereby reducing the load on the heated drying medium source.

Abstract: A web (16) running from an opening nip (K1) between a cylinder (10) and a supporting fabric (18) toward a roll (14), is supported by a negative pressure created by a blow box (30). In an intensified negative pressure region (34?), i.e. close to the disengaging point (40) between the supporting fabric and the cylinder, the pressure is greater than at a distance from this disengaging point. The negative pressure is controlled according to parameters which act on the runability of the web and which can be varied, such as web velocity, web solid contents, pulp composition, paper or paper board quality, web grammage, a characteristic of the web, such as porosity, traction acting in the web, or web tension, cylinder temperature, and/or the running situation, such as a web break, a threading situation, or a normal run, so the desired runability is maintained between the cylinder and the roll.

Abstract: The device (10) and method are used for ventilating an offset pocket space (12) located in a drying section of a papermaking machine by injecting air from a heated dry air supply inlet (11). The offset pocket space (12) is situated between a set of three axially-parallel drying cylinders (20) over which consecutively runs a paper web (14). The device (10) comprises a first air outlet (50) where a first air stream is directed into a cleft (34) defined where the felt (16) rejoins the felt roll (26), and a second air outlet (52) where a second air stream is directed in close proximity to the felt (16) at a location which is upstream of the cleft (34). In use, the device (10) and the corresponding method allow the first air stream to flow through the felt (16) and lift the paper web (14) away from the felt (16) so as to reach the offset pocket space (12). The second air stream creates an air curtain to lower the pressure in a zone between the first (50) and the second air outlet (52).

Abstract: Device and process for removing a fibrous material web from a drying section of a machine for producing and/or refining the fibrous material web and into a catch device. The drying section includes heated drying cylinders, guidance rolls, and at least one drying wire arranged such that the fibrous material web is guided through the drying section over the heated drying cylinders and the guidance rolls at least predominately by the at least one drying wire. The device includes at least one controllable separating device arranged to at least reduce an adhesion force between the fibrous material web and the at least one drying wire.

Abstract: The invention concerns a dryer section, comprising at least one dryer group (R) that makes use of single-wire draw and/or twin-wire draw and at least one suction roll (10) with which the web (W) to be dried is in direct contact. The surface construction of the suction roll (10) is of a fine structure so that the web (W) can be passed to run over the suction roll (10) in direct contact with the roll so that the web (W) is not damaged.

Abstract: The ventilator is used to ventilate an offset pocket in the drying section of a papermaking machine. The papermaking machine comprises a row of spaced-apart upper drying rolls and a row of spaced-apart lower drying rolls. It also comprises two rows of spaced-apart felt rolls disposed intermediate the upper drying rolls and the lower drying rolls, respectively, and a paper web intermittently carried by two felts entrained over the upper drying rolls and over the lower drying rolls, respectively. The ventilator comprises a ventral face and a dorsal face. The ventral face comprises at least one ventral orifice disposed adjacent to the felt and the dorsal face comprises at least one dorsal orifice disposed adjacent to a combined draw of felt and paper web.

Abstract: The device (10) and method are used for ventilating an offset pocket space (12) located in a drying section of a papermaking machine by injecting air from at least one heated dry air supply inlet (11). The offset pocket space (12) is situated between three axially-parallel drying cylinders (20) over which consecutively runs a paper web (14). A first and a third of these cylinders (20) are vertically spaced from a second one. The paper web (14) is pressed against the first and the third cylinder (20) by a felt (16) which further runs around a felt roll (26) having a rotation axis parallel to that of the cylinders (20). The felt roll (26) is disposed between the three cylinders (20) in an offset position which is closer to the first cylinder (20) than the third cylinder (20).

Abstract: Apparatus and process for dewatering a material web. The apparatus includes at least one pressure chamber formed by at least four substantially parallel rolls, a device arranged to introduce a pressurized gas into the at least one pressure chamber, and the at least four substantially parallel rolls being displaceable relative to one another to change an effective area of the at least one pressure chamber. The material web is guided through the at least one pressure chamber. The process includes pressurizing at least one pressure chamber with a gas medium, guiding the material web through the pressure chamber, driving water out of the material web using gas pressure within the at least one pressure chamber, and changing an effective area of the pressure chamber so as to adjust a dewatering capacity.

Abstract: A method and apparatus effect drying of a paper web using a plurality of heated drying cylinders and at least one air impingement module having a hood. The paper web is brought into operative contact with the heated drying cylinders, and at least one of the final moisture content, quality, and cross-direction profile of the paper web is regulated. The regulation is effected by adjusting the efficiency of air impingement drying of the paper web, by adjusting at least one of the blowing velocity of the medium (typically air) blown against the paper web, the humidity of the blowing medium, and the distance of the hood of the impingement module from the paper web. At least one of the final moisture content of the paper web and its quality may also be regulated by adjusting the steam pressure of one or more drying cylinder groups.

Abstract: A sheet stabilizer is provided for a dryer section of a paper-making machine which conveys a wet sheet of paper by way of a felt or fabric, the dryer roller including a leading upper dryer roller, a lower dryer roller, and a trailing upper dryer roller. The sheet stabilizer comprises upper and lower Venturi boxes, which are disposed between the leading upper dryer roller and the lower drying roller. Each Venturi box provides a respective space defined by fixed parallel outer and inner plates. In use, the wet sheet of paper is in sliding contact with the upper outer plate. The upper and lower Venturi boxes cooperate to draw air from the nip between the wet sheet of paper and the lower dryer roller and into both the upper fixed space and the lower fixed space. The sliding contact between the supported wet sheet of paper and the upper outer plate assures that the air flow does not result in fluttering of the wet sheet of paper.

Abstract: A blow box used in the drying section of a papermaking machine and a method for sealing a pocket provided with a blow box, and a blow nozzle. The blow box is arranged to eject air away from the space between a wire and the blow box and/or maintain an underpressure zone in this space. In the interface between the desired underpressure zone and an outside volume, the blow box is provided with a sealing element, such as a blow nozzle, protruding towards the wire to a certain distance “d” seen from the wire, for forming a seal between the underpressure zone and the area remaining outside the underpressure zone. The sealing element is connected to the blow box so that the element may be moved away from the wire to a distance “D” by a push and/or by an actuator, the distance “D” being greater than the distance “d”.

Abstract: A dry end of a machine for manufacturing a material web, in particular a paper or cardboard web, includes at least one convection drier, having at least one drying section. The material web passes through the at least one drying section, and is guided between two air-permeable wire belts.

Abstract: A system (20) and associated process for use in the dryer section (18) of a papermachine for promoting complete support of the paper web (32) by the carrier fabric (34) as the fabric and web are transferred between adjacent drying cylinders (22, 24) by way of a turning roll (26) utilizes a blowbox assembly (50) positionable within the pocket region (40) bounded by the drying cylinders and the turning roll. The blowbox assembly is adapted to direct air out of the pocket region to reduce the likelihood of separation of the web from the carrier fabric as the web is moved onto and off of the turning roll.

Abstract: A web drying apparatus, e.g., for a paper web, includes several heatable drying cylinders arranged in at least one row with at least one respective endless loop drying wire and preferably arranged in two rows of cylinders with two respective wires. A wire guide roll is between and offset from two of the adjacent cylinders in the one row. The one endless loop dryer wire carries the web thereon on a first part of the web loop path from the first cylinder to the wire guide roll. There the web separates from the wire and travels to a second cylinder in the second row. The wire wraps around the wire guide roll and returns on a second part of the web loop path to the next cylinder in the first row, without supporting a web. On the path between the first and third cylinders and around the wire guide roll, the wire defines a loop. An air guide box and a blower are arranged within the loop. The air guide box produces a vacuum at the first part of the wire loop path for drawing the web against the wire.

Abstract: A dryer section in a papermaking machine has two reversing rolls to form a pocket between each pair of dryers in a dryer tier. The first reversing roll is a vacuum roll and the second reversing roll is a grooved roll. A blow box is disposed between the two rolls, the blow box provides suction for the grooved roll and provides vacuum which restrains a web on the dryer fabric as it travels between the first and the second rolls. The blow box also provides a supply of make-up air which extends in a cross machine direction along the pocket formed by the two reversing rolls. The blow box also supports a pivoting foil which is positioned against the dryer fabric as it moves from a first dryer, towards the first reversing roll. The foil defines a region of low pressure which restrains the web as it travels between the first dryer and the first reversing roll.

Abstract: A method for drying a cellulose web, in particular a moist paper web evincing a dry-state specific surface weight of between 10 and 80 g/m.sup.2 and initially a solids content between 8 and 30% approximately, and including supporting the web on a permeable conveying fabric and having a high-speed flow of hot air pass through the web, is characterized in that the flow of air is generated by a relative negative pressure of 100 to 500 mbars generated underneath the fabric.

Abstract: In the device disclosed, a paper web is carried on a belt and stabilized by an underpressure produced by a box opposite the roll, the paper web being sucked by the underpressure against the belt. Located in the box, immediately following the underpressure zone, may be a pressure zone which assists to transfer the paper web to the roll. In an alternative embodiment, a fan can be avoided. Instead the air entrained by the rapidly running belt is deflected by a wedge-shaped deflector and passed over a slit to generate an underpressure inside the box.

Abstract: When drying a paper web (4) in a dryer section (1) of a paper machine provided with drying cylinders (2, 3) and drying wires (5, 6), shrinkage of the paper web in cross direction is counteracted by applying forces at its edge portions (11). According to the invention partial vacuum is maintained along the edge portions of the web within substantially the entire free draw (10) and is applied from the side of the drying wire (5, 6) facing away from the web (4) so that the web is sucked firmly against the drying wire by forces greater than the contracting forces acting in cross direction, thereby counteracting shrinking, said partial vacuum being set within the interval 0.1-0.8 bar, preferably 0.2-0.5 bar.

Abstract: A method and apparatus for impingement drying and/or through-drying of a paper or material web in which the web is dried by blowing hot air and/or superheated steam and/or equivalent from an impingement drying device in a direction substantially perpendicular to the web, and the web is passed on support of a wire or equivalent past the impingement drying device. In the area of the impingement drying device, the web and wire are supported from the opposite side of the wire, opposite in relation to the web, by blowings produced from vacuum blow box substantially across the entire width of the web. One set of blowings from the blow box are blown at a speed substantially higher than the speed of the drying wire. The outlet direction of the blowings is substantially the same as the running direction of the drying wire in this area, and as such, steam and/or air is/are ejected out of the space between the drying wire and the wall placed in connection with the blow boxes that produce the blowings.

Abstract: A machine for producing a material web, e.g., a paper or cardboard web, with a dryer section including at least one dryer group having a plurality of dryer cylinders and a plurality of web guide rolls, e.g., suction web guide rolls. At least one web guide roll, and preferably all, may be associated with an external suction box. Further, a jacket of the at least one web guide roll may include a plurality of through openings and at least one groove formed in an outer surface of the jacket. A predetermined number, and preferably all, of the through openings may be coupled with a bottom portion of the at least one groove to enable the external suction box to suction the at least one web guide roll.

Abstract: An improved two-tier, single-felted dryer section has an upper tier of spaced apart dryer drums and a lower tier of spaced apart dryer drums. The section includes at least one dryer drum group consisting of a first and second adjacent drum in one tier, a third drum in the other tier located between the adjacent first and second drums, and two reversing rolls positioned one on each of the opposite sides of the third drum. A felt-supported paper web follows a serpentine path about the dryer drums and reversing rolls. As a result, the felt-supported web passes through the dryer drum group with the web in direct contact with each of the three dryer drums in the dryer drum group.

Abstract: A limiting orifice through-air-drying apparatus for papermaking or other absorbent embryonic webs. The apparatus has a first zone and a second zone. The first zone is maintained at a differential pressure less than the breakthrough pressure, while the second zone is maintained at a differential pressure greater than the breakthrough pressure. The residence time of the embryonic web to be dried with the apparatus is maintained at preferably less than 35 milliseconds on the first zone. Using the dual zone system described above, the overall energy required to run the apparatus can be reduced.

Abstract: The present invention is a method and apparatus for eliminating the flutter of a paper web in the dryer section of a papermaking machine between two single felt configurations in which the web is transferred from a dryer fabric of a first configuration onto a dryer fabric of a second configuration along a common run of the fabrics, the transfer being effected from one fabric to the other by means of a vacuum transfer roll, with the second configuration dryer fabric being brought into contact with the web and around which the fabric is winding, whereby on the side of the first configuration dryer fabric upstream of a contact point between the web carried thereon and the second configuration dryer fabric winding around the vacuum transfer roll there is provided a vacuum zone defined by the first configuration dryer fabric for retaining the web in contact with the first configuration dryer fabric.