WO2016083172A1

WO2016083172A1 - Device for producing a fibrous web

Info

Publication number: WO2016083172A1
Application number: PCT/EP2015/076652
Authority: WO
Inventors: Klaus-Peter OLTROGGE; Thomas RÜHL; Marc HARMS; Daniel Gronych
Original assignee: Voith Patent Gmbh
Priority date: 2014-11-28
Filing date: 2015-11-16
Publication date: 2016-06-02

Abstract

A device (10) for producing a fibrous web, in particular for producing packaging paper or corrugated board, comprises a former (12) for dewatering a fibre suspension and forming a fibrous web from the fibre suspension, a press section (14) for further dewatering the fibrous web and a drying section (16) for drying the fibrous web. The former, which comprises a single-layer or multiple-layer stock inlet (18), is designed as a hybrid or gap former. The press section comprises a press unit (20), in particular a shoe press unit, having a single press nip (22) extended in the direction of movement (L) of the web.

Description

Apparatus for producing a fibrous web

The invention relates to a device for producing a fibrous web, in particular a packaging paper or pulp web, with a former for dewatering a pulp suspension and to form a fibrous web from the pulp suspension, a press section for further dewatering of the fibrous web and a dryer section for drying the fibrous web. Together with paperboard, packaging papers make up the largest share of packaging materials in practice. They are universally applicable, clean and flexible. The packaging papers include all types of corrugated board, sack paper for the paper sacks, classic brown packaging paper and also the top layers of plasterboard. They usually have a high proportion of recovered paper. Corrugated material is used in the production of corrugated cardboard as a middle layer between two liner layers, i. the two layers used on the inside and outside of the corrugated cardboard packaging or cardboard used. It is usually made from 100% recycled paper. The required strengths are achieved by applying starch.

For the production of packaging papers with a weight per unit area in the range of 50 g / m ² to 170 g / m ² , two-ply paper machines with a four-felted TandemNipcoFlex press, ie a press unit with two press nips extended in the direction of web travel, are used as standard. In order to meet the sheet compaction and strength requirements, in particular when the paper produced is used as corrugating medium, and in order to ensure a sufficiently high dry content for reliable further web guidance. lent, were always always at least two press nips required, which is associated with relatively high investment costs.

The invention has for its object to provide a suitable in particular for the production of packaging paper or corrugating medium device of the type mentioned, which brings less investment costs while maintaining the highest possible quality of the fibrous web to be produced. The device should in particular also meet the respective Blattverdichtungs- and strength requirements for the fibrous web to be produced and ensure safe web guiding.

The object is achieved by a device having the features of claim 1. Preferred embodiments of the device according to the invention will become apparent from the dependent claims, the following description and the drawings.

The apparatus according to the invention for producing a fibrous web, in particular a packaging paper or corrugated web, comprises a former for dewatering a pulp suspension and for forming a fibrous web from the pulp suspension, a press section for further dewatering the fibrous web and a dryer section for drying the fibrous web. In this case, the shaper comprising a single-layer or multi-layer casserole is designed as a hybrid or gap former. The press section comprises a press unit, in particular a shoe press unit, with only one press nip extended in the web running direction. In this case, the press section preferably has only this one press unit. The headbox may be provided as a single-layer headbox or as a multi-layer headbox, in particular a two-layer headbox.

Under a hybrid former is a former with an at least substantially horizontal pre-dewatering zone and an adjoining, in particular special to be understood by a twin-wire former formed further dewatering zone, wherein the pre-dewatering zone may be formed by a horizontal portion of the lower wire of the Doppelsiebformers. The sieves are endless circulating sieve belts. A gap former is a special twin-wire former which can be provided with forming strips arranged in the loop of at least one of the two screens and in particular can be inclined relative to the horizontal.

Due to this design, while maintaining the highest possible quality of the fibrous web to be produced results in a simpler compact design, whereby the investment costs for the device are minimized accordingly. The device is particularly suitable for the production of packaging paper or corrugating medium. The respective Blattverdichtungs- and strength requirements for the fibrous web to be produced can be met in a simple manner in particular by a suitably adapted form of extended in web running direction press nips or the shape of the shoe of the shoe press concerned and length of the press nips and higher line loads. In addition, results from the two-sided drainage in the former a good symmetrical pre-compression.

Preferably, the press nip of the press unit has a length measured in the web running direction in the range of about 100 mm to about 500 mm, and preferably in the range of about 250 mm to about 400 mm. The pressing unit is preferably designed for a line load in the press nip of at least 1000 kN / m, in particular at least 1200 kN / m and preferably at least 1400 kN / m.

With a press nip or press unit adapted in this way in conjunction with the former designed as a hybrid or gap former, in particular the sheet compaction and strength requirements for use of the fibrous web produced as packaging paper or corrugating met and ensures a sufficiently high dry content for safe further web guide. The pressing unit is advantageously designed as a shoe press unit with in particular a shoe press roll and a counter roll.

According to a preferred practical embodiment of the device according to the invention, the former is designed as a hybrid former which comprises a predewatering zone formed by an at least substantially horizontal section of a lower screen onto which pulp suspension can be applied by means of the single-layer or multi-layer casserole, wherein the former subsequently also comprises a double-wire zone formed by the lower wire and an upper wire, in which the pulp suspension is further dehydrated. In this case, the twin-wire zone can be provided in particular in the form of a so-called Duoformers or D-part, which may comprise at least one suction element such as a Obersiebsaugkasten, in particular pneumatically employed Formierleisten and in particular a separating sucker for subsequent separation of the fibrous web of one of the two wires at the end of the twin-wire zone ,

In particular, the former can also be formed by a gap former, which is a special twin-wire former, which can again be provided with molding strips and, in particular, can be inclined at an angle to the horizontal.

The extended in the web running direction press nip the press unit is preferably double felted, whereby a two-sided drainage is effected.

In this case, the fibrous web is extended after the stretched in the running direction double felted Pressnip the pressing unit preferably separated by means of a arranged in the loop of the lower felt of the pressing unit separating suction from the upper felt and passed through the lower felt. The two felts are endless circulating felt ribbons.

According to an advantageous embodiment, the respective separation duration is provided with less than five and preferably with three suction slots.

After the double-felted press nip of the press unit, which has been elongated in the web running direction, the fibrous web can be separated from the top felt, for example, by means of a suction felt roll arranged in the loop of the bottom felt of the press unit, and passed on through the underfelt.

In this case, the lower felt may in particular be guided around the Saugfilzwalze corresponding to a wrap angle greater than 15 °, in particular greater than 30 ° and preferably greater than 40 °.

According to a preferred practical embodiment, the device for producing a fibrous web having a dry weight basis weight or at one of these downstream roller for rolling up the finished fibrous web in the range of about 40 g / m ² to about 120 g / m ² , preferably in Range of about 50 g / m ² to about 90 g / m ² executed.

The fiber material contained in the pulp suspension may in particular consist of 100% recycled fibers.

According to a further preferred practical embodiment, the former comprises a high-vacuum suction element which is in particular subjected to a negative pressure in the range from about 50 kPa to about 80 kPa. In doing so, this high Vacuum suction, for example, be arranged in the loop of one of the two screens of a twin-wire zone of the former.

In the preferably a twin-wire zone with a top wire and a bottom wire comprising former, the proportion of dewatering amount through the top wire is advantageously at least 30% of the total dewatering amount.

The press section can expediently also include a steam blower box 72 (see Fig. 3). The steam blower box 72 is expediently arranged in front of the shoe press, acting upwards in the area downstream of a removal suction roll 74.

The transfer path 70, along which the fibrous web is continued from the top felt of the press unit with separating sucker 42 on the lower felt of the press unit to the transfer to the dryer section, is expediently shorter than 2 m, preferably shorter than 1, 6 m.

Instead of the separating sucker, it is also possible, for example, to provide a felt suction guide roll 73 (see FIG. 4). In this case, the transfer section 71 downstream of the suction felt guide roll 73 can be, in particular, less than or equal to 1 m, wherein it is preferably less than or equal to 0.6 m.

The first guide roller within the loop of the lower felt of the press unit after the transfer line, along which the fibrous web is continued from the separation of the upper felt of the press unit on the lower felt of the press unit to the transfer to the dryer section, can be advantageously provided with a drive.

For the removal of the fibrous web from the lower felt of the pressing unit after the extended in the web running direction press nip, for example, a suction roll be provided. In this case, this suction roller may be arranged to transfer the fibrous web to a drying wire in the loop of this dryer. Such a dryer fabric is an endless circulating dryer fabric belt.

It is particularly advantageous if the fibrous web together with the top and bottom felt of the press unit at an angle of about +/- 5 °, preferably from about +/- 3 ° to the normal to the press plane or the connection of the centers of the press rolls the press unit from the extended in the web running direction press nip leak.

The drying section may advantageously comprise a single-row pre-drying section. In particular, it is also advantageous if a first drying group of the dryer section has at most three drying cylinders, such a first drying group preferably having two drying cylinders.

The jacket of the upper press roller of the press unit can advantageously be provided with an open, in particular grooved surface. In this case, this press roll is preferably associated with a trough for water thrown off from the roll.

The invention will be described in more detail below with reference to an embodiment with reference to the drawing; in this show:

1 is a schematic representation of the former of an exemplary embodiment of a device according to the invention for producing a fibrous web, in particular a packaging paper or pulp web, 2 is a schematic representation of the press section and the dryer section of the apparatus of FIG. 1,

3 is a schematic representation of a modified embodiment of the press section and the dryer section,

4 shows a schematic illustration of a further modified embodiment of the press section and the dry section and

Fig. 5 is a schematic representation of another modified embodiment of the press section and the dryer section.

1 and 2 show a schematic representation of an exemplary embodiment of an apparatus 10 according to the invention for producing a fibrous web, in particular a packaging paper or pulp web, with a former 12 for dewatering a pulp suspension and for forming a fibrous web from the pulp suspension, a press section 14 for further dewatering of the fibrous web and a drying section 16 for drying the fibrous web.

In this case, the presser 14 and the dryer section 16 of the device 10 are shown in FIG. 1, the former 12 and in FIG.

The former 12 comprises a headbox 18, which may be provided as a single-layer or multi-layer casserole. In the present case, this head box 18 is designed for example as a two-layer casserole. Incidentally, the former 12 may be provided in particular as a hybrid or gap former, wherein in the present case it is embodied, for example, as a hybrid former. The press section 14 comprises a press unit 20 with only one press nip 22 extended in the web running direction L. In this case, this press unit 20 may, as illustrated, be designed in particular as a shoe press unit. In the present case, this press unit 20 comprises, for example, an upper shoe press roll 26 and an underlying counter roll 24. In the present case, the press section 14 only has this one press unit 20.

The press nip 22 of the press unit 20 may, for example, have a length measured in the web running direction L in the range of about 100 mm to about 500 mm, and preferably in the range of about 250 mm to about 400 mm.

In addition, the pressing unit 20 can be designed, for example, for a line load in the press nip 22 of at least 1000 kN / m, in particular at least 1200 kN / m and preferably at least 1400 kN / m. In the present case, the former 12 is designed as a hybrid former which comprises a predewatering zone 30 formed by an at least substantially horizontal section of a lower screen 28 onto which pulp suspension can be applied by means of the head box 18, and subsequently by a lower wire 28 and a second Upper screen 32 comprises formed twin-wire zone 34, in which the pulp suspension is further dehydrated. The sieves 28, 32 are endless circulating sieve belts.

The twin-wire zone 34 may be formed by a twin-wire former and in particular a so-called duo-former, which may be provided, for example, with an upper vacuum suction box 36 and, for example, in the loop of the lower wire 28 arranged pneumatically employed forming strips 38 may be provided. The former 12 may include a suction sieve roll 40 or may be provided without such a sieve suction roll. The former 12 can thus be designed, in particular, as a combined Fourdrinier and Duo-former, wherein, as already mentioned, it may comprise a sieve suction roll or it may also be embodied without such a sieve suction roll.

The upper sieve suction box 36 can in particular be designed as a high vacuum suction element, which is subjected to a negative pressure in the range from about 50 kPa to about 80 kPa.

Subsequent to the twin-wire zone 34, the fibrous web is continued through the lower wire 28. To separate the fibrous web from the upper wire 32 may be provided in the loop of the lower wire 28, for example, a separating sucker 42.

The extended in web direction L press nip 22 of the press unit 20 is double-felted in the present case, for example.

The fibrous web is made after the double-felted press nip 22 of the press unit 20 which is elongated in the web running direction L by means of a separating sucker 56 arranged in the loop of the lower felt 44 of the press unit 20 (see also Figures 3 and 5) or a Saugfilzleitwalze 73 (see FIG. 4) separated from the upper felt 46 and continued through the lower felt 44. If a separating sucker is provided for the purpose of separation, it can be provided in particular with less than five and preferably with three suction slots. The two felts 44, 46 are endless circulating felt tapes. If a suction roll is provided for separating the fibrous web from the upper felt 46, then the lower felt 44 can be guided around the suction roll, for example corresponding to a wrap angle greater than 15 °, in particular greater than 30 ° and preferably greater than 40 °.

The first guide roller 48 within the loop of the lower felt 44 of the pressing unit 20 after the transfer line, along which the fibrous web is continued from the separation from the upper felt 46 of the press unit 20 on the lower felt 44 of the pressing unit 20 to the transfer to the drying section 16, for example be provided with a drive.

To remove the fibrous web from the lower felt 44 of the pressing unit 20 after the extended in the web running direction L press nip 22, for example, a suction roll 50 may be provided. In this case, this suction roller 50 may be arranged for transferring the fibrous web to a drying wire 54 in the loop of this drying wire 54. The dryer fabric 54 is an endless circulating dryer fabric belt.

The drying section 16 comprises a plurality of drying cylinders 52. In particular, it may also comprise a single-row pre-drying section. For example, a drying section with a first drying group is also conceivable which has at most three drying cylinders and preferably two drying cylinders.

The jacket of the upper press roller 26 of the press unit 20 may be provided, for example, with an open, in particular grooved surface. In this case, this pressure roller 26 may be associated with a trough for centrifuged water from the pressure roller 26.

3 shows a schematic representation of a modified embodiment of the press section 14 and the drying section 16 with a web running direction L. arranged in the region after a arranged within the loop of the upper felt 46 take-off roller 74. Following the shoe press again a separating sucker 56 is provided. In this case, in the present case, the transfer path 70, along which the fibrous web is guided from the separation of the upper felt 46 of the pressing unit 20 in the region of the separating sucker 56 on the lower felt 44 of the pressing unit 20 to the transfer in the drying section 16, in particular shorter than 2m, preferably shorter be 1, 6 m. 4 shows a schematic representation of a further modified embodiment of the press section 14 and the drying section 16 without steam blower box, in which instead of the separating suction a Saugfilzleitwalze 73 is provided. In the present case, the transfer distance 71 after the Sauffilzleitwalze 73 in particular less than or equal to 1 m, and preferably less than or equal to 0.6 m.

Fig. 5 shows a schematic representation of another modified embodiment of the press section 14 and the drying section 16, which differs from the embodiment of FIG. 3 essentially only in that it is provided without steam blower box.

Incidentally, the press section 14 and the drying section 16 shown in FIGS. 3 to 5 may at least substantially again have the same structure as the press section and the dryer section described with reference to FIG. 2, wherein like reference numerals are assigned to corresponding parts. LIST OF REFERENCE NUMBERS

10 device

12 shaper

14 press section

16 drying section

18 headbox

20 press unit

22 Press nip

24 mating roll

26 shoe press roll

28 lower sieve

30 pre-dewatering zone

32 upper sieve

34 twin-wire zone

36 upper sieve suction box, high vacuum suction nozzle

38 molding strip

40 sieve suction roll

42 vacuum cleaner

44 underfelt

46 top felt

48 guide roller

50 guide roller

52 drying cylinders

54 drying wire

56 Vacuum cleaner

70 transfer line to separating vacuum 56

71 Transfer line to Saugfilzleitwalze73

72 steam box

73 suction felt guide roll Decrease suction web track

Claims

claims

Apparatus (10) for producing a fibrous web, in particular a packaging paper or pulp web, with a former (12) for dewatering a pulp suspension and forming a fibrous web from the pulp suspension, a press section (14) for further dewatering the fibrous web and a dryer section (16 ) for drying the fibrous web, wherein the former (12) comprises a single-layer or multi-layer headbox and is designed as a hybrid or Gapformer and the press section (14) a press unit (20), in particular a shoe press unit, with only one in the web running direction (L) extended press nip (22) includes.

Device according to claim 1,

Thereby, the press nip (22) of the press unit (20) has a length measured in the web running direction (L) in the range of about 100 mm to about 500 mm and preferably in the range of about 250 mm to about 400 mm.

Apparatus according to claim 1 or 2,

characterized in that the press unit (20) is designed for a line load in the press nip (22) of at least 1000 kN / m, in particular at least 1200 kN / m and preferably at least 1400 kN / m.

Device according to at least one of the preceding claims, characterized in that the pressing unit (20) as a shoe press unit with a shoe press roll (26) and a counter-roller (24) is executed.

Device according to at least one of the preceding claims,

characterized in that the former (12) is designed as a hybrid former comprising a pre-dewatering zone (30) formed by an at least substantially horizontal section of a lower wire (28), onto which by means of the single-layer or multi-layer cake (18) fiber suspension and subsequently comprising a double-wire zone (34) formed by the lower wire (28) and an upper wire (32) in which the pulp suspension is further dewatered.

Device according to claim 5,

This means that the former (12) is designed as a gap former.

Device according to at least one of the preceding claims, characterized in that the former (12) is a

Siebsaugwalze includes.

Device according to one of claims 1 to 5,

By doing so, the former (12) is designed without a suction sieve roller.

9. Device according to at least one of the preceding claims,

characterized in that in the web running direction (L) extended press nip (22) of the pressing unit (20) is double felted.

10. Apparatus according to claim 9,

characterized in that the fibrous web after the in the web running direction (L) extended double felted press nip (22) of the pressing unit (20) by means of a in the loop of the lower felt (44) of the pressing unit (20) arranged separating suction from the upper felt (46) and separated by the underfelt (44) is continued.

11. The device according to claim 10,

This ensures that the vacuum cleaner is provided with less than five and preferably three suction slots.

12. Device according to at least one of the preceding claims,

In this way, the fibrous web, after the double-felted press nip (22) of the press unit (20) which is elongated in the web running direction (L), is replaced by a loop in the lower felt (44) of the press unit (20)

Press unit (20) arranged Saugfilzwalze separated from the upper felt (46) and continued through the lower felt.

13. Device according to claim 12,

characterized in that the lower felt (44) is guided around the Saugfilzwalze corresponding to a wrap angle greater than 15 °, in particular greater than 30 ° and preferably greater than 40 °. 14. Device according to at least one of the preceding claims,

characterized in that it is for producing a fibrous web having a basis weight after the dryer section (16) or at one of these downstream roller in the range of about 40 g / m ² to about 120 g / m ² , preferably in the range of about 50 g / m ² to about 90 g / m ² is performed. Device according to at least one of the preceding claims, characterized in that the fiber material contained in the pulp suspension consists of 100% recycled fibers.