EP1105563B1 - Press section in a paper machine, in which press section one or several extended nips is/are applied - Google Patents
Press section in a paper machine, in which press section one or several extended nips is/are applied Download PDFInfo
- Publication number
- EP1105563B1 EP1105563B1 EP99923626A EP99923626A EP1105563B1 EP 1105563 B1 EP1105563 B1 EP 1105563B1 EP 99923626 A EP99923626 A EP 99923626A EP 99923626 A EP99923626 A EP 99923626A EP 1105563 B1 EP1105563 B1 EP 1105563B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- press
- nip
- roll
- zone
- extended
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/04—Arrangements thereof
Definitions
- the invention concerns a paper machine, comprising a press section and a dryer section, according to the preamble of claim 1.
- the structure of paper in particular of printing paper, must also be symmetric.
- Good printing properties required from printing paper mean good smoothness, evenness and certain absorption properties of both faces.
- the properties of paper, in particular the symmetry of density, are affected considerably by the operation of the press section of a paper machine, which operation also has a decisive significance for the evenness of the profiles of the paper in the cross direction and in the machine direction.
- the first nip in a press of the SymPress IITM type is a two-felt nip, and therein the upper roll is a suction roll, by the effect of whose vacuum the web follows the upper felt, which is, at the same time, the pick-up felt.
- This solution operates well in a SymPress IITM press.
- the holding zone subjected to a vacuum starts from the first nip and continues up to the following nip, and the level of the vacuum has been arranged to be adjustable. Further, the coverage of the lower felt on the upper felt after the first nip has been regulated such that the runnability is good and that rewetting is minimized.
- a roll nip in which one of the rolls is a suction roll limits the linear load to a maximal level of 100...150 kN/m.
- the linear load can be raised up to 300...400 kN/m (max. 1500...2000 kN/m, depending on the backup roll), and the length of the nip can be varied, so that the dry solids content of the web that is achieved is higher and better controllable than with a roll nip.
- WO 97/13030 A discloses a paper machine comprising the features of the preamble of claim 1.
- the object of the present invention is to provide novel press section concepts in which it is largely possible to avoid the drawbacks discussed above and to provide a press section that, for its part, permits, if necessary, an increase of the running speed of a paper machine to the range of ⁇ 2000 m/min.
- the rewetting arising from the other felt after the nip is reduced, because the web is no longer in contact with said felt. Also, the rewetting arising from the felt that the web follows is reduced, because the vacuum in the suction roll keeps the water better in the felt, and the web absorbs less water as it expands (in the z-direction). Since, in the press section in accordance with the invention, the web already chooses the correct felt in the nip, after the nip no separate transfer suction roll or equivalent is needed, by whose means the web could be forced to follow the correct felt. By means of such a transfer suction roll, abrasion might be caused in the web, because at a transfer suction roll the felts may have different speeds or tensions.
- an extended-nip zone in the last nip in the press wherein a sufficiently long time of dwell is obtained in the last nip while, nevertheless, employing a sufficiently low peak compression pressure, in which case both a good and reliable transfer of the web, owing to the suction roll applied in the extended nip, and a sufficiently high dry solids content of the web are achieved, which dry solids content is realized partly because an extended nip in itself has a good dewatering capacity, which is increased further by the suction roll also used as a backup roll in the extended nip, at the same time as rewetting is avoided.
- the press section in accordance with the invention is particularly well suitable for the manufacture of all printing and writing paper grades, whose basis weight is, as a rule, lower than 100 g/m 2 .
- a preferred embodiment of the invention is particularly well suited in which two successive extended nips are used, both of which are two-felt nips, in which case a particularly symmetric dewatering and, thereby, symmetry in the z-direction, which is required from printing papers, are achieved.
- a press suction roll when used in an extended nip as the backup roll of the hose roll, owing to the high nip loads it is preferable to use a sufficiently large suction roll diameter D ⁇ 800...2000 mm and a thickness of the mantle of the suction roll higher than normal, s ⁇ 50...120 mm.
- a press suction roll in the present invention, it is also possible to use a variable-crown roll or an adjustable-crown roll, such as the applicant's roll with the trade mark SymZTMRoll.
- the suction zone of the press suction roll is extended to the width of the extended-nip zone only or just slightly beyond said width, in which case the width of the suction sector on the press suction roll is, as a rule, in the range ⁇ 8°...16°, preferably in the range ⁇ 10°...14°.
- Figure 1 is a schematic illustration of the preferred embodiment of the invention, in which two successive extended-nip zones arranged in accordance with the invention and a fully closed draw of the web from the forming wire to the drying wire are employed.
- Figures 2A, 2B, 2C, 2D, 2E, 2F, 2G, and 2H illustrate different variations of arrangements of the first press nip in a press section in accordance with the invention.
- Figures 3A, 3B, 3C, 3D, 3E, and 3F are illustrations corresponding to Figs. 2A...2H of arrangements of the second and the last nip in a press section in accordance with the invention and of the draw of the web to the dryer section.
- Fig. 1 illustrates the exemplifying embodiment of the invention that is, according to current knowledge, the most advantageous one, in particular in paper machines that produce printing and writing papers.
- the paper web W is separated from the forming wire 10 at the pick-up point P and transferred onto the suction zone 35a of the pick-up roll 35 onto the first upper felt 31, which is guided by its guide rolls 33.
- the upper felt 31 carries the web W into the first extended nip NP1, which is provided with two felts and in which the lower felt is the lower felt 41 guided by the guide rolls 43, which carries the web W further after the extended-nip zone NP1.
- the web W is carried on the top face of the lower felt 41 as a straight run over the blow suction box 44 onto the second upper felt 32, onto which it is transferred on the suction zone 36a of the transfer suction roll 36. After this the web W is carried on the lower face of the second upper felt 32 over the blow suction boxes 34 into the second extended nip NP2, after which the web W follows the second lower felt 42, which is guided by its guide rolls 43.
- the web W is passed from the second extended nip NP2 to the transfer point S, at which the web W is transferred with the aid of the suction zone 50a of the transfer suction roll 50 onto the drying wire 51, which runs over blow suction boxes 52 onto the first drying cylinder 53 in the dryer section and from said cylinder further in a known way.
- the function of the blow suction boxes 34 and 44 placed between the extended-nip zones NP1 and NP2 is to keep the web W in contact with the felt 41,32.
- the extended nips NP1 and NP2 have been formed between an upper shoe roll or hose roll 11 and 12 and a lower press suction roll 21,22 provided with a suction zone 23.
- the construction of the upper hose rolls 11,12 of the extended nips NP1 and NP2 is in itself known and comprises a flexible hose mantle 14, in whose interior there is a press shoe 13 which can be loaded by means of a hydraulic pressure medium and by whose means the necessary compression pressure can be applied to the web W running between the felts 31,41;32,42 so that water is transferred in both nips NP1,NP2 into both felts substantially symmetrically so that a web sufficiently symmetric in the z-direction is obtained, which web has two identical faces.
- Such a paper is particularly suitable for writing or printing paper.
- the vacuum present in the suction zones 23 of the press suction rolls 21,22 it is secured that, after the two nips NP1,NP2, the web W follows the lower felt 41,42, in which case the lower felt 41,42 can be separated from the upper felt 31,32 directly after the nip zone, whereby rewetting of the web is substantially prevented.
- the extent of the suction zones 23 of the press suction rolls 21,22 is, as a rule, just about 8°...16°, preferably ⁇ 10°...14°, and extends to the width of the extended-nip zone or zones.
- the press suction roll 21 and/or 22 is/are used in an extended-nip zone, said roll 21/22 must be measured more robust than a normal suction roll in order to endure the high linear loads in the extended nip.
- the diameter of the press suction roll 21/22 is, as a rule, chosen in the range D ⁇ 800...2000 mm.
- the thickness of the perforated mantle of the press suction roll 21/22 and the perforations in said mantle are also dimensioned in view of high nip loads.
- the thickness s of the mantle of the suction roll 21/22 is, as a rule, chosen in the range s ⁇ 50...120 mm.
- the proportion of the open area in the mantle of the suction roll 21/22 i.e. the percentage of holes R, is, as a rule, chosen in the range R ⁇ 10...40 %.
- the strength of the mantle of the suction roll 21/22 can also be increased by means of choice of its material.
- the level of vacuum P effective in the suction zone 23 of the press suction roll 21/22 is, as a rule, chosen in the range p ⁇ 30...70 kPa, depending on the application.
- Figs. 2A...2H illustrate different variations of embodiments of the first press nip in accordance with the invention.
- Figs. 3A...3F illustrate different variations of carrying out the second nip in accordance with the invention and the last nip in the press section.
- the first press nips shown in Figs. 2A, 2B, 2C, and 2D are suitable for use in particular in connection with the last nip in any one of the press sections shown in Figs. 3A and 3B.
- press sections can be carried into effect favourably as the combinations 2A + 3A, 2A + 3B, 2B + 3A, 2B + 3B, 2C + 3A, 2C + 3B, 2D + 3A, 2D + 3B.
- combinations of Figs. 2E + 3C, 2E + 3D, 2F + 3C, 2F + 3D, 2G + 3E, 2G + 3F, 2H + 3E, 2H + 3F are particularly usable.
- the first two-felt 31,41 nip is a roll nip N1, which is formed between two, preferably water-receiving hollow-faced press rolls 61 and 71.
- the first nip N1 is a roll nip which is formed between an upper, preferably hollow-faced press roll 61 and a lower press suction roll 21, which is provided with a suction zone 23.
- the first nip is an extended nip NP1, which is formed between an upper hose roll 11 and a lower press suction roll 21 provided with a suction zone 23.
- Fig. 2A the first two-felt 31,41 nip is a roll nip N1, which is formed between two, preferably water-receiving hollow-faced press rolls 61 and 71.
- the first nip N1 is a roll nip which is formed between an upper, preferably hollow-faced press roll 61 and a lower press suction roll 21, which is provided with a
- the first nip is an extended nip NP1, which is formed between an upper hose roll 11 and a lower smooth-faced or hollow-faced 72 press roll 71, which is not a suction roll, but which, if necessary, can be a variable-crown roll, such as a roll marketed by the applicant with the trade mark SymZLTM Roll.
- the second and the last nip in the press in accordance with Fig. 3A, is formed between an upper press suction roll 22 and a lower hose roll 12.
- the hose roll 12 and the press suction roll 22 are placed in an inverse order, as compared with Fig. 3A.
- the roll nips N1, the extended nips NP1 and the second extended nips NP2 shown in Figs. 2A...2D and 3A and 3B are, all of them, two-felt 31,41;32,42 nips.
- the web is passed on the upper felt 32 placed at the side of the press suction roll 22 as a closed draw onto the drying wire 51 of the dryer section, onto which wire the web is transferred while secured by the vacuum present in the suction zone 50a of the transfer suction roll 50.
- the web W is passed after the last nip NP2 on the top face of the lower felt 42 placed at the side of the press suction roll 22 onto the drying wire 51.
- the first nip NP1 is an extended nip, in which the lower roll is a hose roll 11 and the upper roll a press suction roll 21, owing to whose suction zone 23 the web W follows the upper felt 31, from which the web W is separated onto the suction zone 45a of the transfer suction roll 45 and is transferred onto the lower felt 42 passing into the second nip.
- the lower roll is a hose roll 11 and the upper roll a press suction roll 21, owing to whose suction zone 23 the web W follows the upper felt 31, from which the web W is separated onto the suction zone 45a of the transfer suction roll 45 and is transferred onto the lower felt 42 passing into the second nip.
- the first nip is a roll nip N1
- the lower roll is a press roll 71, whose mantle is smooth-faced or hollow-faced
- the upper roll 21 is a press suction roll, owing to whose suction zone 23 the web W follows the upper felt 31, from which it is transferred onto the suction zone 45a of the transfer suction roll 45 onto the lower fabric 42 that passes into the second nip.
- the last nip in the press section shown in Figs. 3C and 3D, is an extended nip NP2, which is formed between a hose roll 12 and a press suction roll 22.
- the web W follows the upper felt 32 owing to the suction zone 23 of the press suction roll 22, on which felt 32 the web is transferred onto the drying wire 51, and, similarly, in Fig. 3D, the web follows the lower felt 42.
- the first nip NP1 is an extended nip, in which the upper roll is a hose roll 11 and the lower roll a press roll 71, which is smooth-faced 72.
- the lower fabric in the first extended nip NP1 is a smooth-faced transfer belt 41B, which does substantially not receive water and which, thus, does not rewet the web W.
- the web W follows the smooth outer face of the transfer belt 41B, from which it is transferred with the aid of the suction zone 36a of the transfer suction roll 36 onto the upper fabric of the second nip N2. As is shown in Fig.
- the upper fabric in the first extended nip NP1 is a smooth transfer belt 31B.
- the upper roll in the nip NP1 is a hose roll 11, and the lower roll 71 is a hollow-faced 72 press roll. After the nip NP1, the web follows the smooth face of the transfer belt 31B, from which it is transferred onto the lower felt 42 of the second nip. As is shown in Fig.
- the second and the last nip in the press section which nip is an extended nip NP2
- nip is an extended nip NP2
- the web follows the upper fabric 32, from which it is transferred as a closed draw onto the drying wire 51.
- hose roll 12 and the press suction roll 22 have inverse positions, so that, after the nip NP2, the web W follows the lower felt 42.
- the run of the web through the whole press section is highly linear so that there are no major curves in the run of the web, which curves might subject the web to such high dynamic forces that the web is separated from the supporting face, such as a press felt or a transfer belt.
- the largest angle a of change in direction of the web W is in connection with the second extended nip NP2, a ⁇ 30°...40°.
- said maximal angle of change in direction is in a range a ⁇ 45°, preferably a 30°.
- the angle of change in direction corresponds to the width of the suction sector 23 of the press suction roll 21, 22, which sector 23 is, as was stated above, relatively little and extends just over the extended-nip zone NP1/NP2 or slightly beyond said zone.
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- Paper (AREA)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI981089A FI111859B (fi) | 1998-05-15 | 1998-05-15 | Paperikoneen puristinosa, jossa sovelletaan yhtä tai useampaa pitkänippiä |
FI981089 | 1998-05-15 | ||
PCT/FI1999/000394 WO1999060202A1 (en) | 1998-05-15 | 1999-05-11 | Press section in a paper machine, in which press section one or several extended nips is/are applied |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1105563A1 EP1105563A1 (en) | 2001-06-13 |
EP1105563B1 true EP1105563B1 (en) | 2004-03-17 |
Family
ID=8551740
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99923626A Expired - Lifetime EP1105563B1 (en) | 1998-05-15 | 1999-05-11 | Press section in a paper machine, in which press section one or several extended nips is/are applied |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP1105563B1 (fi) |
AT (1) | ATE262074T1 (fi) |
CA (1) | CA2333280A1 (fi) |
DE (1) | DE69915645T2 (fi) |
FI (1) | FI111859B (fi) |
WO (1) | WO1999060202A1 (fi) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FI116401B (fi) * | 2000-02-22 | 2005-11-15 | Metso Paper Inc | Paperi- tai kartonkikone, jossa on muodostusosa ja puristinosa |
FI116400B (fi) | 2002-11-19 | 2005-11-15 | Metso Paper Inc | Paperi- tai kartonkikoneen puristinosa |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FI95610C (fi) * | 1994-10-06 | 1996-02-26 | Valmet Paper Machinery Inc | Tasauspuristimella varustettu paperikoneen puristinosa |
FI98843C (fi) * | 1995-10-03 | 1997-08-25 | Valmet Corp | Menetelmä ja laite veden poistamiseksi paperi- tai kartonkiradasta puristamalla |
-
1998
- 1998-05-15 FI FI981089A patent/FI111859B/fi not_active IP Right Cessation
-
1999
- 1999-05-11 WO PCT/FI1999/000394 patent/WO1999060202A1/en active IP Right Grant
- 1999-05-11 AT AT99923626T patent/ATE262074T1/de not_active IP Right Cessation
- 1999-05-11 DE DE69915645T patent/DE69915645T2/de not_active Expired - Fee Related
- 1999-05-11 EP EP99923626A patent/EP1105563B1/en not_active Expired - Lifetime
- 1999-05-11 CA CA002333280A patent/CA2333280A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
FI981089A (fi) | 1999-11-16 |
DE69915645D1 (de) | 2004-04-22 |
CA2333280A1 (en) | 1999-11-25 |
FI981089A0 (fi) | 1998-05-15 |
DE69915645T2 (de) | 2005-02-03 |
ATE262074T1 (de) | 2004-04-15 |
FI111859B (fi) | 2003-09-30 |
EP1105563A1 (en) | 2001-06-13 |
WO1999060202A1 (en) | 1999-11-25 |
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