CA1314166C - Method for use in the press section of a paper machine - Google Patents
Method for use in the press section of a paper machineInfo
- Publication number
- CA1314166C CA1314166C CA000550936A CA550936A CA1314166C CA 1314166 C CA1314166 C CA 1314166C CA 000550936 A CA000550936 A CA 000550936A CA 550936 A CA550936 A CA 550936A CA 1314166 C CA1314166 C CA 1314166C
- Authority
- CA
- Canada
- Prior art keywords
- press
- web
- roll
- felt
- nip
- 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 - Fee Related
Links
- 238000000034 method Methods 0.000 title claims abstract description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 5
- 230000008030 elimination Effects 0.000 abstract 1
- 238000003379 elimination reaction Methods 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 19
- 230000035611 feeding Effects 0.000 description 7
- 238000001035 drying Methods 0.000 description 2
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
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
Landscapes
- Paper (AREA)
Abstract
Abstract The invention relates to a method for use in the press section of a paper machine. In the method, a web to be dried is led through the press section by closed feeding by passing it through nips between press rolls as a closed feeding through the press sec-tion. The web is led through at least two nips remov-ing water from the web, one nip being formed between two press rolls having a separate felt loop and the other between a suction roll having the separate felt loop and belonging to the first nip as the other press roll thereof and a third press roll having a separate felt loop. For the elimination of the rewetting after the second nip the web is after the second nip separ-ated at least from the surface of the felt moving around the suction roll belonging to the first nip.
(Figure 1)
(Figure 1)
Description
13~16~
A method for use in the press section of a paper machine The invention relates to a method for use in the press section of a paper machine, wherein a web to be dried is led through the press section by closed feeding by passing it through nips between press rolls so that the web is constantly in contact with the sur-face of at least one felt, and wherein the web is led through at least two nips removing water from the web, one nip being formed between two press rolls having a separate felt loop and the other between a suction roll provided with the separate felt loop and belong-ing to the first nip as one press roll thereof and a third press roll having a separate felt loop.
This kind of press solutions are well-known in connection with paper machines. An example of prior solutions would be the method described in U.S. Patent Specification 4 272 316. In this prior solution the nips are formed by three press rolls in such a manner that a suction roll forming the middlemost press roll forms one of the press rolls in both nips. Each one of the three press rolls is provided with a separate felt loop, so that the web to be dried is positioned be-tween two felts in both nips.
A drawback of this prior solution is that the web to be dried is passed on to a subsequent treating step between two felts, i.e. in such a manner that after having passed through the nip the web makes con-tact with a felt moving around the suction roll. This results in rewetting problems, whereby the water re-moved from the web to the felt during the pressing tends to return to the web after the nip.
However, this solution has been used, because it has been taken for granted in the art that the web ~¢, 13~416~
~ 2 cannot be detached from th~ surface of a felt after having been sucked thereto without damaging the web surface. ~ compromise has thereby been resorted to by accepting the rewetting of the web due to the fact t!hat it is simpler to remove the moistness than to re-pair a damaged web surface.
Other examples of slightly different applica-tions include the solutions disc:losed in Finnish Patent Specifications 50 652 and 66 666. These sol-utions differ from the solution of U.S. Patent Speci-fication 4 272 316 in that one of the nips is formed between a third press roll which does not have a felt loop and a suction roll having a felt loop.
A drawback of the above solutions is the diffi-cult use thereof since the web feeding, for instance, is difficult to carry out. In addition, these prior solutions provide poor draina~e properties. In this kind of prior press solutions, clifficulties arise in the web feeding at running speeds exceeding 10 m/s.
The object of the invention is to provide a method by means of which the drawbacks of the prior art can be eliminated. This is achiaved by means of a method according to the invention which is character-ized in that the web is after the second nip se-parated at least from the surface of the felt moving around the suction roll belonging to the first nip According to a broad aspect of the present invention there is provided a method for use in a press section of a paper machine and wherein a wet web to be dried is led through the press section by closed feeding by passing it through nips between press rolls so that the web is constantly in contact with the surface of at least one felt. The web is led through at least two nips for removing water from the web. A first nip is B
131~66 - 2a -formed between a first press roll and a suction roll constituting a second press roll. Each of the rolls has a respective separate felt loop. A second nip is formed between the suction roll and a third press roll, which also has a respective separate felt loop, wherein the web is after the second nip separated at least from the surface of the respective felt loop which moves around the suction xoll.
A major advantage of the solution according to the invention is that a press utilizing the method can be operated even at running speeds exceeding 1000 m/min and nevertheless the drying degree is higher than with prior solutions. Improvement in the drying degree is due to the partial prevention of the rewett-ing phenomenon. The method according to the invention is also convenient for the operator because, for in-stance, there are no such web feeding problems as with 131kl~6 prior solutions. This is due to the closed feeding of the web. Another advantage of the invention is that it can be carried out flexibly so that the invention can also be advantageously taken into use in connection with existing press solutions.
The invention will be described in the follow-ing in more detail with reference to the preferred em-bodiments shown in the attached drawings, whereby Figure 1 is a general side view of a press sec-tion of a paper machine utilizing the method according to the invention, and Figure 2 illustrates another embodiment of the method according to the invention in the press section of a paper machine.
In the example of Figure 1, a web 1 to be dried is led to the press section on a wire 3 moving around a roll 2. The web 1 to be dried is detached from the wire 3 by means of a roll 4. The web 1 is d~tached from the wire 3 by suc~ion from within ~he roll 4.
After having been detached, the web is passed forwards on a felt 5 moving around the roll 4.
The web 1 positioned on the felt 5 is led on to the felt 6 so as to be positioned between the felts 5 and 6.
The web 1 is transported between the felts 5 and 6 to a first nip Nl which is formed between press rolls 7 and 8. The felt 5 is thus arranged to move both around the roll 4 and the press roll 8. The felt 6, in turn, is arranged to move around the press roll 7. The press roll 8 is a suction roll and a grip zone 9 thereof sucks the web 1 into contact with the felt 5, whereby the web is detached from the surface of the felt 6 and is passed on the felt 5 ~owards a second nip N2 formed between the press roll 8 and a third press roll 10.
131~1~6 The third press roll 10 is provided with a se-parate felt loop formed by a felt 11. At the second nip N the web 1 to be dried is positioned between the felts 5 and 11.
After the nip N2 the web 1 is separated from the surface of the felt moving around the press roll 8, so that the rewetting is prevented.
The web 1 is passed on towards a subsequent treating step on the surface of the felt 11 moving around the third press roll 10. The subsequent treat-ing step may thereby be e.g. a subsequent press 12 formed by rolls 13, 14. The rolls 13, 14 preferably form an extended press zone N3, a so called extended nip. The felt 11 is thereby preferably arranged to move around the press roll 14, too. The press roll 13 is provided with a separate felt loop 15 as is con-ventional. The moisture transferred to the felt 11 in the second nip can be removed prior to the press 12 e.g. by means of a felt suction box 16.
The embodiment of Figure 1 is preferably used when the invention is applied to a new apparatus, i.e.
in cases where the utilization of the invention has been taken into consideration from the very beginning of the planning of the new apparatus.
The embodiment shown in Figure 2 can be util-ized in an existing apparatus. The example of Figure 2 is fully similar to that of Figure 1 up to the second nip. Accordingly, the same reference numerals as in Figure 1 have been used in Figure 2 at corresponding points.
The web 1 to be dried is brought to the nip N1 quite similarly as is described above in connection with Figure 1. The loops of the felts 5, 6 are ar-ranged similarly as in the example of Figure 1. The nips N1, N2 are formed in the same way as in Figure 1, i.e. by means of the press rolls 7, 8 and 10. The press roll 8 is a suction roll.
The example of Figure 2 differs from that of Figure 1 in that a felt 110 moving around the third press roll 10 is a separate felt which does not move around a press roll 14 of the subsequent press 12. The press roll 14 is thus provided with a separate felt loop 111.
In the solution of Figure 2, the web to be dried is after the nip Nl first separated from the surface of the felt 5 and thereafter also from the surface of the felt 110 moving around the third press roll 10. The web 1 is thereby forwarded by open feed-ing to a subsequent treating step which may be e.g.
the subsequent press 12. In this embodiment the press rolls 13, 14 of the press 12 are have separate felt loops lS, 111. The rolls 13, 14 preferably form an ex-tended press zone N3, a so called extended nip.
The solution of Figure 2 can be especially ad-vantageously applied to existing apparatuses by pro-viding these with the felt 110 moving around the third press roll. The structures of the press 12 need not be modified.
The above embodiments are by no means intended to restrict the invention' but the invention can, of course, be modified in various ways within the scope of the claims. Accordingly, it is obvious that when applying the method according to the invention, the felt loops need not be exactly similar to those shown in the figures but other kind of solutions are poss-ible as well. Naturally, any suitable solutions can be used in the press rolls and in the guide rolls of the felts, etc.
A method for use in the press section of a paper machine The invention relates to a method for use in the press section of a paper machine, wherein a web to be dried is led through the press section by closed feeding by passing it through nips between press rolls so that the web is constantly in contact with the sur-face of at least one felt, and wherein the web is led through at least two nips removing water from the web, one nip being formed between two press rolls having a separate felt loop and the other between a suction roll provided with the separate felt loop and belong-ing to the first nip as one press roll thereof and a third press roll having a separate felt loop.
This kind of press solutions are well-known in connection with paper machines. An example of prior solutions would be the method described in U.S. Patent Specification 4 272 316. In this prior solution the nips are formed by three press rolls in such a manner that a suction roll forming the middlemost press roll forms one of the press rolls in both nips. Each one of the three press rolls is provided with a separate felt loop, so that the web to be dried is positioned be-tween two felts in both nips.
A drawback of this prior solution is that the web to be dried is passed on to a subsequent treating step between two felts, i.e. in such a manner that after having passed through the nip the web makes con-tact with a felt moving around the suction roll. This results in rewetting problems, whereby the water re-moved from the web to the felt during the pressing tends to return to the web after the nip.
However, this solution has been used, because it has been taken for granted in the art that the web ~¢, 13~416~
~ 2 cannot be detached from th~ surface of a felt after having been sucked thereto without damaging the web surface. ~ compromise has thereby been resorted to by accepting the rewetting of the web due to the fact t!hat it is simpler to remove the moistness than to re-pair a damaged web surface.
Other examples of slightly different applica-tions include the solutions disc:losed in Finnish Patent Specifications 50 652 and 66 666. These sol-utions differ from the solution of U.S. Patent Speci-fication 4 272 316 in that one of the nips is formed between a third press roll which does not have a felt loop and a suction roll having a felt loop.
A drawback of the above solutions is the diffi-cult use thereof since the web feeding, for instance, is difficult to carry out. In addition, these prior solutions provide poor draina~e properties. In this kind of prior press solutions, clifficulties arise in the web feeding at running speeds exceeding 10 m/s.
The object of the invention is to provide a method by means of which the drawbacks of the prior art can be eliminated. This is achiaved by means of a method according to the invention which is character-ized in that the web is after the second nip se-parated at least from the surface of the felt moving around the suction roll belonging to the first nip According to a broad aspect of the present invention there is provided a method for use in a press section of a paper machine and wherein a wet web to be dried is led through the press section by closed feeding by passing it through nips between press rolls so that the web is constantly in contact with the surface of at least one felt. The web is led through at least two nips for removing water from the web. A first nip is B
131~66 - 2a -formed between a first press roll and a suction roll constituting a second press roll. Each of the rolls has a respective separate felt loop. A second nip is formed between the suction roll and a third press roll, which also has a respective separate felt loop, wherein the web is after the second nip separated at least from the surface of the respective felt loop which moves around the suction xoll.
A major advantage of the solution according to the invention is that a press utilizing the method can be operated even at running speeds exceeding 1000 m/min and nevertheless the drying degree is higher than with prior solutions. Improvement in the drying degree is due to the partial prevention of the rewett-ing phenomenon. The method according to the invention is also convenient for the operator because, for in-stance, there are no such web feeding problems as with 131kl~6 prior solutions. This is due to the closed feeding of the web. Another advantage of the invention is that it can be carried out flexibly so that the invention can also be advantageously taken into use in connection with existing press solutions.
The invention will be described in the follow-ing in more detail with reference to the preferred em-bodiments shown in the attached drawings, whereby Figure 1 is a general side view of a press sec-tion of a paper machine utilizing the method according to the invention, and Figure 2 illustrates another embodiment of the method according to the invention in the press section of a paper machine.
In the example of Figure 1, a web 1 to be dried is led to the press section on a wire 3 moving around a roll 2. The web 1 to be dried is detached from the wire 3 by means of a roll 4. The web 1 is d~tached from the wire 3 by suc~ion from within ~he roll 4.
After having been detached, the web is passed forwards on a felt 5 moving around the roll 4.
The web 1 positioned on the felt 5 is led on to the felt 6 so as to be positioned between the felts 5 and 6.
The web 1 is transported between the felts 5 and 6 to a first nip Nl which is formed between press rolls 7 and 8. The felt 5 is thus arranged to move both around the roll 4 and the press roll 8. The felt 6, in turn, is arranged to move around the press roll 7. The press roll 8 is a suction roll and a grip zone 9 thereof sucks the web 1 into contact with the felt 5, whereby the web is detached from the surface of the felt 6 and is passed on the felt 5 ~owards a second nip N2 formed between the press roll 8 and a third press roll 10.
131~1~6 The third press roll 10 is provided with a se-parate felt loop formed by a felt 11. At the second nip N the web 1 to be dried is positioned between the felts 5 and 11.
After the nip N2 the web 1 is separated from the surface of the felt moving around the press roll 8, so that the rewetting is prevented.
The web 1 is passed on towards a subsequent treating step on the surface of the felt 11 moving around the third press roll 10. The subsequent treat-ing step may thereby be e.g. a subsequent press 12 formed by rolls 13, 14. The rolls 13, 14 preferably form an extended press zone N3, a so called extended nip. The felt 11 is thereby preferably arranged to move around the press roll 14, too. The press roll 13 is provided with a separate felt loop 15 as is con-ventional. The moisture transferred to the felt 11 in the second nip can be removed prior to the press 12 e.g. by means of a felt suction box 16.
The embodiment of Figure 1 is preferably used when the invention is applied to a new apparatus, i.e.
in cases where the utilization of the invention has been taken into consideration from the very beginning of the planning of the new apparatus.
The embodiment shown in Figure 2 can be util-ized in an existing apparatus. The example of Figure 2 is fully similar to that of Figure 1 up to the second nip. Accordingly, the same reference numerals as in Figure 1 have been used in Figure 2 at corresponding points.
The web 1 to be dried is brought to the nip N1 quite similarly as is described above in connection with Figure 1. The loops of the felts 5, 6 are ar-ranged similarly as in the example of Figure 1. The nips N1, N2 are formed in the same way as in Figure 1, i.e. by means of the press rolls 7, 8 and 10. The press roll 8 is a suction roll.
The example of Figure 2 differs from that of Figure 1 in that a felt 110 moving around the third press roll 10 is a separate felt which does not move around a press roll 14 of the subsequent press 12. The press roll 14 is thus provided with a separate felt loop 111.
In the solution of Figure 2, the web to be dried is after the nip Nl first separated from the surface of the felt 5 and thereafter also from the surface of the felt 110 moving around the third press roll 10. The web 1 is thereby forwarded by open feed-ing to a subsequent treating step which may be e.g.
the subsequent press 12. In this embodiment the press rolls 13, 14 of the press 12 are have separate felt loops lS, 111. The rolls 13, 14 preferably form an ex-tended press zone N3, a so called extended nip.
The solution of Figure 2 can be especially ad-vantageously applied to existing apparatuses by pro-viding these with the felt 110 moving around the third press roll. The structures of the press 12 need not be modified.
The above embodiments are by no means intended to restrict the invention' but the invention can, of course, be modified in various ways within the scope of the claims. Accordingly, it is obvious that when applying the method according to the invention, the felt loops need not be exactly similar to those shown in the figures but other kind of solutions are poss-ible as well. Naturally, any suitable solutions can be used in the press rolls and in the guide rolls of the felts, etc.
Claims (4)
1. A method for use in the press section of a paper machine, wherein a wet web to be dried is led through the press section by closed feeding by passing it through nips between press rolls so that the web is constantly in contact with the surface of at least one felt, and wherein the web is led through at least two nips for removing water from the web, a first nip being formed between a first press roll and a suction roll constituting a second press roll, each said roll having a respective separate felt loop, and a second nip being formed between the suction roll and a third press roll, which also has a respective separate felt loop, wherein the web is separated immediately after the second nip from the surface of the said respective felt loop which moves around the suction roll.
2. A method according to claim 1, wherein the web is separated only from the surface of the said respective felt loop which moves around the suction roll and is led to a subsequent treatment zone on the surface of the said respec-tive felt loop which moves around the third press roll.
3. A method according to claim 1, wherein the web is first separated from the surface of the said respective felt loop which moves around the suction roll and thereafter also from the surface of the said respective felt loop which moves around the third press roll whereafter the web is led to a subsequent treatment zone by feeding known per se.
4. A method according to claim 2 or 3, wherein the subsequent treatment zone is an extended press zone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI864735A FI90097C (en) | 1986-11-20 | 1986-11-20 | FOERFARANDE VID PRESSPARTI FOER PAPPERSMASKIN |
| FI864735 | 1986-11-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1314166C true CA1314166C (en) | 1993-03-09 |
Family
ID=8523527
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000550936A Expired - Fee Related CA1314166C (en) | 1986-11-20 | 1987-11-03 | Method for use in the press section of a paper machine |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1314166C (en) |
| DE (1) | DE3737332A1 (en) |
| FI (1) | FI90097C (en) |
| GB (1) | GB2197667B (en) |
| SE (1) | SE467624B (en) |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4075056A (en) * | 1974-08-15 | 1978-02-21 | Beloit Corporation | Press section structure |
| FR2343858A1 (en) * | 1976-03-12 | 1977-10-07 | Neyrpic Bmb | IMPROVEMENT IN THE PRESSED SECTIONS OF PAPER MACHINES AND FIBER SAILS |
| FI770542A (en) * | 1977-02-18 | 1978-08-19 | Valkama P J | PRESS RELEASE FOR THE CONSTRUCTION OF VAT ON FIBER BAN |
| FI770540A (en) * | 1977-02-18 | 1978-08-19 | Schauman Wilh Oy | FRAMEWORK FOR THE FRAMEWORK OF PAPERBOARD ELLER ANNAN DYLIK FIBERBANA MED TAENJBARHET OCH / ELLER HOEG FRIKTIONSKOEFFICIENT |
| US4197158A (en) * | 1978-03-16 | 1980-04-08 | Beloit Corporation | Paper making machine press section |
| US4272316A (en) * | 1979-05-29 | 1981-06-09 | Beloit Corporation | Steam shower |
| FI813875L (en) * | 1981-12-03 | 1983-06-04 | Valmet Oy | PRESS SPART WITH NYP FOER PAPPERS- ELLER CARTON MASK |
| US4483745A (en) * | 1982-09-29 | 1984-11-20 | Beloit Corporation | Method and apparatus of sheet transfer using a nonporous smooth surfaced belt |
| SE466660B (en) * | 1986-06-03 | 1992-03-16 | Valmet Paper Machinery Inc | MAJORLY ENDED PRESS PARTY IN A PAPER MACHINE |
-
1986
- 1986-11-20 FI FI864735A patent/FI90097C/en not_active IP Right Cessation
-
1987
- 1987-10-30 SE SE8704236A patent/SE467624B/en not_active IP Right Cessation
- 1987-11-03 CA CA000550936A patent/CA1314166C/en not_active Expired - Fee Related
- 1987-11-04 DE DE19873737332 patent/DE3737332A1/en active Granted
- 1987-11-18 GB GB8727001A patent/GB2197667B/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| FI864735A (en) | 1988-05-21 |
| FI90097C (en) | 1993-12-27 |
| GB2197667A (en) | 1988-05-25 |
| DE3737332A1 (en) | 1988-06-01 |
| FI864735A0 (en) | 1986-11-20 |
| FI90097B (en) | 1993-09-15 |
| SE467624B (en) | 1992-08-17 |
| DE3737332C2 (en) | 1993-01-14 |
| GB8727001D0 (en) | 1987-12-23 |
| SE8704236L (en) | 1988-05-21 |
| SE8704236D0 (en) | 1987-10-30 |
| GB2197667B (en) | 1990-11-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |