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
  • D21F3/045—Arrangements thereof including at least one extended press nip
• • 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
  • D21F3/0281—Wet presses in combination with a dryer roll
• • 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 present invention relates to a paper machine for manufacturing a paper web, comprising: a wet section including a headbox, a former, a clothing that carries a formed paper web from the former; a press section including a shoe press having a shoe press roll and a counter roll; and a drying section including a drying cylinder close to which said counter roll being arranged, whereby the shoe press roll and said counter roll form an extended, first press nip and said counter roll and drying cylinder form a second press nip, in and after which the paper web is transferred to the drying cylinder.
• the invention also relates to a method of manufacturing a paper web in a paper machine comprising: a wet section including a headbox, a former, a clothing that carries a formed paper web from the former; a press section including a shoe press having a shoe press roll and a counter roll; and a drying section including a drying cylinder close to which said counter roll being arranged, whereby the shoe press roll and said counter roll form an extended, first press nip and said counter roll and drying cylinder form a second press nip, in and after which the paper web is transferred to the drying cylinder.
• the paper web is transferred from a forming wire to the impermeable belt which is to carry the paper web on its under side to the press nip and then transfer the paper web to the drying cylinder.
• the adhesion force between the impermeable belt and the paper web is greater than that between the press felt and the paper web.
• the impermeable belt in question here has a smooth, web-carrying surface.
• both the impermeable belt and the drying cylinder in the paper machine according to US-5, 393, 384 have smooth surfaces with which the paper web is intended to come into contact, there is a great risk of the paper web continuing to adhere to the smooth surface of the impermeable-belt after it is passed the nip at the drying cylinder instead of being transferred to the smooth surface to the drying cylinder, as is desired.
• Probably not even the application of large quantities of adhesive on the envelope surface of the drying cylinder would ensure adhesion of the paper web to the drying cylinder.
• WO 94/28240 describes a compact roll press in a paper machine for thin paper.
• a smooth first roll and a second roll form a first press nip through which a web-carrying felt runs.
• the second roll may be a suction roll or a blind-drilled roll.
• the smooth first roll carries the web to a second extended press nip which it forms together with a shoe press roll.
• the smooth, first roll then carries the web to a large cylinder, which may be a
• US-5, 500, 092 describes a paper machine for the production of tissue paper having a press unit consisting of a suction press roll, a shoe press roll and a press roll with smooth surface, which press roll defines a nip with a drying cylinder.
• the press roll with the smooth surface also forms a press nip with the suction press roll and an extended press nip with the shoe press roll .
• a felt is passed through the two last-mentioned press nips and is returned to a place upstream via turning rolls, after having passed the extended press nip.
• the paper web is carried by said felt and runs through the two press nips together with the felt.
• the paper web is carried by the press roll with smooth surface and transferred from this to the drying cylinder when the paper web runs into the nip between them, as illustrated in the drawings in this patent.
• No fabric is present in the nip between the drying cylinder and the press roll with smooth surface. Since both press roll and drying cylinder have smooth surfaces there is a risk of the web accompanying the smooth press roll after the nip instead of adhering to the drying cylinder. Furthermore, the press roll with the smooth surface will be subjected to high temperatures at the nip with the drying cylinder and will then cool down after the nip during its continued rotation. Such temperature fluctuations in the press roll with smooth surface are unfavourable.
• the nip is described as a press nip but it is not possible to take care of any water pressed out of the web.
• the object of the present invention is to provide an improved paper machine of the type described in the introduction, which has a press section with two press nips but which is still compact, and which paper machine ensures that the paper web follows the intended path of run. It is also an object of the invention to provide an improved method of manufacturing a paper web using such a paper machine .
• the paper machine according to the invention is characterized in that the shoe press has a first endless clothing which carries the formed paper web up to said extended, first press nip and which runs in a loop around the shoe press roll through the extended first press nip, and a second endless clothing which constitutes a felt running in a loop in which the counter roll is situated, through the extended, first press nip and through the second press nip.
• the method according to the invention is characterized in that the formed paper web is carried by a first endless clothing of the shoe press, up to said extended, first press nip, which first clothing runs in a loop around the shoe press roll through the extended first press nip, and in that, at least in the press nip, the paper web is brought into contact with a second endless clothing which constitutes a felt running in a loop in which the counter roll is situated, through the extended, first press nip and through the second press nip .
• Figure 1 shows a paper machine for manufacturing a paper web of soft paper according to a first embodiment of the invention.
• Figure 2 shows a paper machine for manufacturing a paper web of soft paper according to a second embodiment of the invention.
• Figure 3 shows a paper machine for manufacturing a paper web of soft paper according to a third embodiment of the invention.
• Figure 4 shows a paper machine for manufacturing a paper web of soft paper according to a fourth embodiment of the invention.
• Figure 5 shows a paper machine for manufacturing a paper web of soft paper according to a fifth embodiment of the invention.
• Figure 6 shows a paper machine for manufacturing a paper web of machine-glazed paper according to a sixth embodiment of the invention.
• Figure 7 shows a paper machine for manufacturing a paper web of machine-glazed paper according to a seventh embodiment of the invention.
• FIG. 1 shows schematically parts of a paper machine for manufacturing a fiber web 1 of soft paper such as tissue and other sanitary paper products.
• the paper machine comprises a wet section 2, a press section 3 and a drying section 4.
• the drying section 4 comprises a drying cylinder 5, the envelope surface of which is sufficiently strong to withstand high pressures such as those occurring during pressing of the paper web.
• the drying cylinder 5 is suitably a Yankee cylinder.
• the wet section 2 comprises a headbox 7 and a former, which may be generally designed as a double-wire former with a forming roll 8, an endless, carrying, inner clothing 9 and an endless covering, outer clothing 10 consisting of a wire.
• the inner and outer clothings 9, 10 run, each in its own loop, around a plurality of guide rolls 11, 12.
• the inner clothing 9 may consist of a substantially impermeable belt, a wire or a felt.
• the press section 3 comprises a shoe press with a shoe press roll 13 and a counter roll 14, and a first endless clothing 16 running in a loop around the shoe press roll 13.
• the shoe press roll 13 and counter roll 14 between them form an extended, first press nip.
• the counter roll 14 is arranged close to the drying cylinder 5 to form a second press nip therewith.
• the press section 3 also has a second endless clothing 15 which is in the form of a press felt and which runs in a loop around guide rolls and around the counter roll 14 so that it passes through the extended, first press nip and the second press nip between the counter roll 14 and drying cylinder 5.
• the web is transferred from the inner clothing 9 to the clothing 16, which is a pick-up felt, with the aid of a suction roll 17.
• the pick-up felt 16 passes two suction boxes 24 and through the extended, first press nip.
• This embodiment thus has a double-felted, extended, first press nip.
• the counter roll 14 is a suction roll which, via the press felt 15, takes care of the water pressed out of the paper web to the press felt 15.
• a suitable adhesive is applied with the aid of an application device 23 on the envelope surface of the drying cylinder 5 just before the second press nip.
• the paper web 1 is creped off the drying cylinder 5 by means of a creping doctor 6, and is then conveyed to a reel-up (not shown) .
• Figure 2 shows schematically a paper machine similar to that in Figure 1 except for the counter roll 14 which in this case is a grooved roll which, via the press felt 15, takes care of the water pressed out of the paper web to the press felt 15.
• the loop of the press felt 15 is extended after the extended, first press nip so that the press felt 15 runs around two guide rolls 25 and thereafter to the second press nip.
• the press water running down from the grooved roll is collected in a suitable device (not shown) situated in the space below the grooved roll inside the loop of the press felt 15.
• the grooved roll is replaced by a blind-drilled roll.
• FIG. 3 shows schematically parts of a paper machine for manufacturing a fiber web 1 of soft paper such as tissue and other sanitary paper products.
• the paper machine comprises a wet section 2, a press section 3 and a drying section 4.
• the drying section 4 comprises a drying cylinder 5, the envelope surface of which is sufficiently strong to withstand high pressures such as those occurring during pressing of the paper web.
• the drying cylinder 5 is suitably a Yankee cylinder.
• the wet section 2 comprises a headbox 7 and a former, which may be generally designed as a double-wire former with a forming roll 8, an endless, carrying, inner clothing 9 and an endless, covering, outer clothing 10 consisting of a wire.
• the inner and outer clothings 9, 10 run, each in its own loop, around a plurality of guide rolls 11, 12.
• the inner clothing 9 may consist of a substantially impermeable belt, a wire or a felt.
• the press section 3 comprises a shoe press with a shoe press roll 13 and a counter roll 14, and a first endless clothing 16 passing around the shoe press roll 13.
• the shoe press roll 13 and counter roll 14 between them form an extended, first press nip.
• the counter roll 14 is arranged close to the drying cylinder 5 to form a second press nip therewith.
• the press section 3 also has a second endless clothing 15 which is in the form of a press felt and which runs in a loop through the extended, first press nip and the second press nip between the counter roll 14 and drying cylinder 5.
• the inner clothing 9 runs from the wet section 2 to the press section 3 and there also forms the first clothing 16 of the shoe press, which clothing 16 runs around the shoe press roll 13 through the extended, first press nip.
• the inner clothing 9, i.e. said other clothing 16 is a felt a double-felted, extended first press nip is also obtained in this embodiment .
• the inner clothing 9 is a felt or wire it runs past two suction boxes 24.
• the counter roll 14 is a grooved roll which, via the press felt 15, takes care of the water pressed out of the paper web to the press felt 15.
• the loop of the press felt 15 is extended after the extended first press nip so that the press felt 15 runs around two guide rolls 25 and then on to the second press nip.
• the press water running down from the grooved roll 14 is collected in a suitable receptacle (not shown) situated in the space below the grooved roll 14 inside the loop of the press felt 15.
• the grooved roll is replaced by a blind-drilled roll.
• the counter roll 14 is a suction roll and the press felt 15 thus runs as shown in Figure 1, i.e. without said extension of the loop of the press felt 15 and without the guide rolls 25.
• An application device 23 is used to apply a suitable adhesive on the envelop surface of the drying cylinder 5 immediately prior to the second press nip.
• the paper web 1 is creped off the drying cylinder 5 with the aid of a creping doctor 6, and is then conveyed to a reel-up (not shown) .
• Figure 4 shows schematically a paper machine turned upside down in relation to that shown in Figure 3 so that the paper web moves in upward direction towards and through the extended first press nip and then encounters a downwardly moving surface of the drying cylinder 5 in the second press nip.
• the paper machine is otherwise similar to that according to Figure 3 with the exception of the counter roll 14 which in this case is a suction roll which, via the press felt 15, takes care of the water pressed out of the paper web to the press felt 15.
• FIG. 5 shows schematically parts of a paper machine for manufacturing a fiber web 1 of soft paper such as tissue and other sanitary paper products .
• the paper machine comprises a wet section 2, a press section 3 and a drying section 4.
• the drying section 4 comprises a drying cylinder 5, the envelope surface of which is sufficiently strong to withstand high pressures such as those occurring during pressing of the paper web.
• the drying cylinder 5 is suitably a Yankee cylinder.
• the wet section 2 comprises a headbox 7 and a former which is a double-wire former of the crescent former type with a forming roll 8, an endless, carrying, inner clothing 9, which consists of a wire, and an endless, covering, outer clothing 10, also consisting of a wire.
• the inner and outer clothings 9, 10 run, each in its own loop, around a plurality of guide rolls 11, 12.
• the press section 3 comprises a shoe press with a shoe press roll 13 and a counter roll 14, and a first endless clothing 16 running 10
• the press section 3 also has a second endless clothing 15 which is in the form of a press felt and which runs in a loop through the extended, first press nip and the second press nip between the counter roll 14 and the drying cylinder 5.
• the web is transferred from the outer clothing 10 to the clothing 16 which may be a pick-up felt, with the aid of a suction roll 17.
• the clothing 16 may also be an impermeable transfer belt.
• the pick-up clothing 16 runs through the extended, first press nip.
• the pick-up clothing 16 is a felt a double-felted, extended first press nip is also obtained in this embodiment.
• the pick-up clothing 16 is a felt it runs past two suction boxes 24.
• the counter roll 14 is a grooved roll which, via the press felt 15, takes care of the water pressed out of the paper web to the press felt 15.
• the loop of the press felt 15 is extended after the extended first press nip so that the press felt 15 runs around two guide rolls 25 and then on to the second press nip.
• the press water running down from the grooved roll 14 is collected in a suitable device (not shown) situated in the space below the grooved roll 14 inside the loop of the press felt 15.
• the grooved roll is replaced by a blind-drilled roll.
• the counter roll 14 is a suction roll and the press felt 15 thus runs as shown in Figure 1, i.e. without said extension of the loop of the press felt 15 and without the guide rolls 25. 11
• An application device 23 is used to apply a suitable adhesive on the envelop surface of the drying cylinder 5 immediately prior to the second press nip.
• the paper web 1 is creped off the drying cylinder 5 with the aid of a creping doctor 6, and is then conveyed to a reel-up (not shown) .
• FIG. 6 shows schematically parts of a paper machine for manufacturing a fiber web 1 of machine-glazed paper.
• the paper machine comprises a wet section 2, a press section 3 and a drying section 4.
• the drying section 4 comprises a drying cylinder 5, the envelope surface of which is sufficiently strong to withstand high pressures such as those occurring during pressing of the paper web.
• the drying cylinder 5 is suitably a Yankee cylinder.
• the wet section 2 comprises a headbox 7 and a former, which can be generally called a fourdrinier former, having a couch roll 19 and an endless clothing 18 in the form of a wire running in a loop around the couch roll 19, a wire suction roll 20 and a plurality of guide rolls 21.
• the press section 3 comprises a shoe press with a shoe press roll 13 and a counter roll 14, and a first endless clothing 16 running in a loop around guide rolls 22 and the shoe press roll 13.
• the shoe press roll 13 and counter roll 14 between them form an extended, first press nip.
• the counter roll 14 is arranged close to the drying cylinder 5 to form a second press nip therewith.
• the press section 3 also has a second endless clothing 15 which is in the form of a press felt and which runs in a loop through the extended, first press nip and the second press nip between the counter roll 14 and the drying cylinder 5.
• the web is transferred in an open draw from the wire 18 to the clothing 16 which may be a pick-up felt or an impermeable 12
• the pick-up clothing 16 passes around the extended, first press nip.
• the pick-up clothing 16 is a felt a doublefelted, extended first press nip is also obtained in this embodiment.
• the pick-up clothing 16 is a felt it runs past two suction boxes 24.
• the counter roll 14 is a grooved roll which, via the press felt 15, takes care of the water pressed out of the paper web to the press felt 15.
• the loop of the press felt 15 is extended after the extended first press nip so that the press felt 15 runs around two guide rolls 25 and then on to the second press nip.
• the press water running down from the grooved roll 14 is collected in a suitable device (not shown) situated in the space below the grooved roll 14 inside the loop of the press felt 15.
• the grooved roll is replaced by a blind-drilled roll.
• the counter roll 14 is a suction roll and the press felt 15 thus runs in the way shown in
• the paper web leaves the drying cylinder 5 in a direction tangential to and around a guide roll 26, to be conveyed to a reel -up (not shown) .
• the reference number 27 indicates a cleaning doctor arranged to scrape deposits off the envelope surface.
• FIG. 7 shows schematically parts of a second paper machine for manufacturing a fiber web 1 of machine-glazed paper.
• the paper machine comprises a wet section 2, a press section 3 and a drying section 4.
• the drying section 4 comprises a drying cylinder 5, the envelope surface of which is sufficiently strong to withstand high pressures such as those occurring during pressing of the paper web.
• the drying cylinder 5 is suitably a Yankee 13
• the wet section 2 comprises a headbox 7 and a former, which can be generally called a fourdrinier former, having a couch roll 19 and an endless clothing 18 in the form of a wire running in a loop around the couch roll 19, a wire suction roll 20 and a plurality of guide rolls 21.
• the press section 3 comprises a shoe press with a shoe press roll 13 and a counter roll 14, and a first endless clothing 16 running in a loop around a suction roll 17, guide rolls 22 and the shoe press roll 13.
• the shoe press roll 13 and counter roll 14 between them form an extended, first press nip.
• the counter roll 14 is arranged close to the drying cylinder 5 to form a second press nip therewith.
• the press section 3 also has a second endless clothing 15 which is in the form of a press felt and which runs in a loop through the extended, first press nip and the second press nip between the counter roll 14 and the drying cylinder 5.
• the web is transferred from the wire 18 to the clothing 16, which is a pick-up felt, with the aid of the suction roll 17.
• the pick-up clothing 16 runs through the extended, first press nip.
• This embodiment thus has a double-felted, extended first press nip.
• the counter roll 14 is a grooved roll which, via the press felt 15, takes care of the water pressed out of the paper web to the press felt 15.
• the paper web is conveyed in upward direction towards and through the extended, first press nip and then encounters a downwardly moving surface of the drying cylinder 5 at the second press nip.
• the loop of the press felt 15 is extended after the extended first press nip so that the press felt 15 runs around two guide rolls 25 and then on to the second press 14
• the press water spraying upwards from the grooved roll 14 is collected in a suitable device (not shown) situated in the space above the grooved roll 14 inside the loop of the press felt 15.
• the grooved roll is replaced by a blind-drilled roll.
• the counter roll 14 is a suction roll, in which case the press felt 15 runs in the way shown in Figure 4, i.e. without said extension of the loop of the press felt 15 and without the guide rolls 25.
• the paper web leaves the drying cylinder 5 in a direction tangential to and around a guide roll 26, to be conveyed to a reel-up (not shown) .
• the reference number 27 indicates a cleaning doctor arranged to scrape deposits off the envelope surface.
• the extended, first press nip of the shoe press is separated from the drying cylinder.
• the distance is in any case so short between the extended first press nip and the drying cylinder that the risk of the web becoming rewetted by the felt is slight, even when the loop of the press felt 15 is extended after the extended, first press nip to pass around the two guide rolls 25.
• the suction roll 17 can in certain cases be replaced by a smooth roll, one or more suction boxes or a suitable guide element which alters the direction of the pick-up felt 16.
• the dry solids content of the paper web before the extended first press nip is within the interval 12-16%.
• pressing in a shoe press instead gives maximum dry solids content and high density, which promotes the properties of machine-glazed paper.
• a high-beaten pulp is generally used for making machine-glazed paper, whereas low-beaten pulp is used for making soft paper.
• the drying cylinder 5 is also used for pressing the paper web.
• the drying cylinder has a hot envelope surface which is beneficial to the pressing process.

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Cited By (6)

Citations (3)

• 1998
  • 1998-02-04 SE SE9800308A patent/SE511485C2/sv not_active IP Right Cessation
• 1999
  • 1999-01-22 WO PCT/SE1999/000090 patent/WO1999040255A1/en active Application Filing

Patent Citations (3)

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