DE102020111746A1 - MACHINE FOR THE MANUFACTURE OR TREATMENT OF A FIBER WEB - Google Patents

Abstract

A machine for producing or treating a fibrous web, in particular a paper or cardboard web, comprises a wire section, a press section and a dryer section. In this case, following the last press nip of the press section, the fibrous web is taken over by a first revolving dryer wire of the dryer section from a revolving lower clothing guided through the last press nip of the press section. The fibrous web, together with the first dryer wire of the dryer section, is guided generally vertically upwards along an impingement drying section along which the underside of the fibrous web is dried by at least one impingement dryer.

Description

The invention relates to a machine for producing or treating a fibrous web, in particular a paper or cardboard web, with a wire section, a press section and a dryer section.

Conventional high-performance paper machines usually have a closed web guide or web guide without free tension between the press section and the pre-dryer section. The paper web is taken over by a dryer wire of the first dryer group either from a transfer belt or a felt. The paper web is preferably removed from a lower covering. This is also the case, among other things, with machines for the production of corrugated cardboard base paper. With such solutions that have been customary up to now, corrugated cardboard base paper can be produced in a stable manner at machine speeds of more than 1500 to a maximum of 1650 m / min. Stable here means production with a runtime efficiency> 90%.

By means of an impingement air or impingement flow dryer, the machine speed can be further increased by approx. 100 to 150 m / min to approx. 1800 m / min without any loss of run time efficiency. Papers contaminated with adhesive particles (stickies, etc.) can be almost completely freed from stickies on the web surface by means of impingement flow or impingement air technology. In all probability, the hot impact air (T> 200 ° C) evaporates the adhesive particles and thus cleans the paper surface. This circumstance would be of great importance for the use of waste paper, if the hypothesis is correct, which has so far been reliably confirmed in practice.

However, the previous solutions mentioned have a number of disadvantages. For example, to transfer the paper web from the press section to the dryer section, a transfer wire group is required, which brings with it a further pick-up or removal position for the paper web. Such a further removal position not only requires a more complex structure of the paper machine, it also represents a potential disturbance point which can lead to breaks, creases, a machine crash or the like. There is always the risk that the edges of the web will fold down, which leads to web breaks and results in a lower running time efficiency.

The invention is based on the object of specifying a machine of the type mentioned at the beginning with which the advantages of the previous solutions are obtained, but whose disadvantages are eliminated in the simplest and most efficient way possible.

This object is achieved by a machine with the features of claim 1. Preferred embodiments of the machine according to the invention emerge from the subclaims, the present description and the drawing.

The machine according to the invention for producing or treating a fibrous web, in particular a paper or cardboard web, comprises a wire section, a press section and a dryer section. In this case, following the last press nip of the press section, the fibrous web is taken over by a first revolving dryer wire of the dryer section from a revolving lower clothing guided through the last press nip of the press section. Together with the first dryer wire of the dryer section, the fibrous web is then guided generally vertically upwards along an impingement drying section, along which the underside of the fibrous web is dried by at least one impingement dryer. The underside of the fibrous web is to be understood as the side of the fibrous web which was in contact with the surrounding lower covering guided through the last press nip of the press section. The upper side is the side of the fibrous web opposite this lower side.

Because of this design, the previously required transfer wire group for transferring the fibrous web from the press section to the dryer section is no longer necessary. Since the fibrous web no longer has to be suspended from a transfer screen or transferred with an overhead web guide, the risk of the web edges folding down is eliminated, so that the risk of web breaks is also minimized and the running time efficiency is increased accordingly. In addition, the transmission time is shortened. In addition, the lower covering of the last press nip of the press section, which is used for the transfer, in combination with the vertical impingement drying, significantly reduces the number of nip passes and enables very high production times from belt change to belt change, which results in less downtime or downtime. The lower covering of the last press nip of the press section, which is used to transfer the fibrous web from the press section to the dryer section, can be relatively heavy and relatively stiff, so that it is difficult to manipulate. Since the fibrous web to be removed from the lower covering of the last press nip of the press section is on top, there is better runability. The more compact design of the machine is also an advantage. With impingement flow or impingement air drying, hot air is blown from nozzles at high speed onto the fibrous web. The hot air gives off heat and absorbs the resulting water vapor.

The lower one, which is guided through the last press nip of the press section, preferably comprises Covering a transfer ribbon. This transfer belt can be relatively long in order to facilitate the transfer to the first dryer fabric of the dryer section.

The transfer tape can be water-impermeable or water-permeable, whereby it is preferably water-impermeable.

The fibrous web is expediently taken over by the lower clothing guided through the last press nip of the press section in the area of a suction roll looped around by the first dryer wire of the dryer section. A reliable transfer of the fibrous web to the first dryer fabric is guaranteed by the suction guide roll.

At least two, preferably at least three, impingement dryers are advantageously provided along the impingement drying section. The underside of the fibrous web is thus dried by an impingement flow over a relatively long impingement-flow drying section, as a result of which efficient drying is achieved.

In order to ensure the most reliable web guidance possible along the impingement drying section, the first dryer fabric of the drying section is guided along the impingement drying section on its side opposite the at least one impingement dryer, advantageously over support rollers and / or stabilizers, in particular stabilizer boxes, which are subjected to negative pressure.

Following the impingement drying section of the first dryer fabric, the fibrous web is expediently taken over from the first dryer fabric by a second circulating dryer fabric of the dryer section.

It is particularly advantageous if the fibrous web is taken over by the first dryer fabric in the area of a suction roll looped around by the second dryer fabric of the dryer section, which ensures reliable transfer to the second dryer fabric.

According to a preferred practical embodiment of the machine according to the invention, the fibrous web is guided together with the second dryer wire of the drying section along a further impingement drying section, along which the upper side of the fibrous web is dried by at least one further impingement dryer. The fact that the upper side of the fibrous web is also dried by an impingement flow results in a more even, more efficient drying of the fibrous web.

In this case, at least two further impingement dryers can advantageously be provided along the further impingement drying section, with at least three or four further such impingement dryers preferably being provided.

In order to ensure the most reliable and stable guidance of the fibrous web along the further impingement drying section, the second dryer wire of the drying section along the further impingement drying section is on its side opposite the at least one impingement dryer, preferably again via support rollers and / or stabilizers, in particular stabilizer boxes, which are subjected to negative pressure , guided.

The last press nip of the press section is advantageously elongated in the direction of travel of the web, whereby it is preferably formed by a shoe press nip. With such an extended or shoe press nip, there is a gentler and more efficient dewatering of the fibrous web.

The fibrous web is passed through the last press nip between the lower covering and a preferably water-absorbing press felt, which loops around an overhead shoe press roll.

In this case, the shoe press nip is preferably formed between an overhead shoe press roll and a lower counter roll of a shoe press that is wrapped around by the lower covering. The mean line force of such a wide-nip press can be> 950 kN / m, in particular> 1200 kN / m.

It is particularly advantageous if the fibrous web, which is guided around the counter roll of the shoe press together with the lower covering, is acted upon by the steam of at least one steam box, in particular high-performance steam box, in the area of the counter roll in front of the shoe press nip. This allows the dewatering performance in the shoe press to be increased accordingly. On the counter roll of the shoe press an additional press roll with an additional, water-absorbing covering wrapped around it, can be provided to form an additional press nip through which the lower covering, the fibrous web and the additional, water-absorbing covering run.

According to an expedient practical embodiment of the machine according to the invention, the press section comprises, in addition to the last press nip, at least two further press nips, one of which is preferably a rotating one The central press roll wrapped around the upper press felt to form a first press nip and a second press nip following it in the direction of travel of the web are assigned to two counter rolls, and the fibrous web between the circulating upper press felt and a circulating lower press felt through the first press nip and between the upper circulating press felt and the circumferential lower covering of the last press nip of the press section is guided through the second press nip. This ensures optimal dewatering of the fibrous web with a relatively compact construction of the press section.

A suction press roll, for example, can be provided as the central press roll.

The central press roll and the counter roll are preferably arranged at a distance.

According to a preferred alternative practical embodiment of the machine according to the invention, the first and the second press nip are formed by shoe press nips of a duo-centri-NipcoFlex press comprising a central deflection adjusting roller.

With such a Duo-Zentri-NipcoFlex press, the line forces of the relevant press nips can be variably adjusted across the width.

The fibrous web is preferably taken over by the upper press felt wrapping around the central press roll from a forming wire of the wire section.

Subsequent to the further impingement drying section, the fibrous web is preferably taken over from the second drying wire by a circulating drying wire of an in particular single-row drying group.

The invention is explained in more detail below using an exemplary embodiment with reference to the drawing.

The single figure of the drawing shows an exemplary embodiment of a machine 10 for the production or treatment of a fibrous web, which can in particular be a paper or cardboard web.

The machine 10 includes a wire section 12th , a press section 14th and a dryer section 16 . The machine or web running direction is shown in the figure with " L. “Indicated.

The fibrous web is after the last press nip 18th the press section 14th through a first circulating dryer wire 20th the dryer section 16 from one through the last press nip 18th the press section 14th guided all-round lower covering 22nd accepted. Then the fibrous web is together with the first dryer wire 20th the dryer section 16 along an impingement drying section 24 , along which the underside of the fibrous web through at least one impingement dryer 24 ' is dried, generally guided vertically upwards.

In the present case, the last press nip includes 18th the press section 14th guided lower covering 22nd a transfer belt. This transfer tape can be water-impermeable or water-permeable, whereby it is preferably water-impermeable.

The fibrous web is in the area of the first dryer wire 20th the dryer section 16 wrapped suction guide roller 28 from the one through the last press nip 18th the press section 14th guided lower covering 22nd accepted.

In the present case, there are, for example, three impingement dryers along the impingement drying section 24 ' intended. In principle, however, more or fewer impingement flow dryers are also conceivable.

The first dryer fabric 20th the dryer section 16 is along the impingement drying section 24 on his impingement dryers 24 ' opposite side over backup rollers 30th and stabilizers subjected to negative pressure 32 out, which in the present case are, for example, stabilizer boxes.

Following the impingement drying section 24 of the first dryer fabric 20th the fibrous web is passed through a second circulating dryer wire 34 the dryer section 16 from the first dryer fabric 20th accepted. The transfer takes place in the area of one of the second dryer fabric 34 the dryer section 16 wrapped suction guide roller 36 .

Then the fibrous web is together with the second dryer fabric 34 the dryer section 16 along another impingement drying section 38 out, along which the top of the fibrous web through at least one further impingement dryer 38 ' is dried. In the present case, for example, there are four such further impingement dryers 38 ' intended. In principle, however, more or fewer further impingement dryers can also be used 38 ' be provided.

The second dryer fabric 34 the dryer section 16 is along the further impingement drying section 38 on his impingement dryers 38 ' opposite side over backup rollers 42 and stabilizers subjected to negative pressure 44 out, which in the present case are, for example, stabilizer boxes.

The last press nip 18th the press section 14th is in the direction of web travel L. extended and formed in the present case by a press shoe nip.

Here is this Schuhpressnip 18th in the illustrated embodiment between an overhead shoe press roll 46 , which is wrapped in a water-absorbing press felt, and one of the lower covering 22nd wrapped underlying counter roll 48 a shoe press.

To improve the drainage performance, it is used together with the lower covering 22nd around the counter roll 48 the shoe press 46 , 48 guided fibrous web in the area of the counter roll 48 before the shoe press nip 18th by the steam of at least one steam box 50 applied, which can in particular be a high-performance steam blower box.

The press section 14th includes in addition to the last press nip 18th for example two more press nips 52 , 54 . In the present case, they are one of a circumferential upper press felt 56 wrapped central press roller 58 to form a first press nip 52 and one in the direction of web travel L. subsequent second press nips 54 two counter rolls 60 , 62 assigned. The fibrous web is between the circumferential upper press felt 5 and a circumferential lower press felt 64 through the first press nip 52 and between which the central press roll 58 surrounding upper all-round press felt 56 and the surrounding lower covering 22nd of the last press nip 18th the press section 14th through the second press nip 54 guided.

As a central press roller 58 In the simplest case, for example, a suction press roll can be provided. However, in particular, such designs are also conceivable in which the first and the second press nip are formed by shoe press nips of a duo-centri-NipcoFlex press comprising a central deflection adjusting roller. The line forces of the relevant press nips can be variably adjusted across the width.

In the present case, the fibrous web is through the central press roll 58 surrounding upper press felt 56 from a forming fabric 66 the wire section 12th accepted.

Following the further impingement drying section 38 the fibrous web is passed through a circulating dryer wire 68 a drying group 70 from the second dryer fabric 34 accepted. In the present case it is the drying group 70 for example a single-tier dryer group with overhead dryer cylinders 72 and deflection suction rollers below 74 to which the drying sieve 68 is led.

For cleaning the through the last press nip 18th the press section 14th guided lower covering 22nd this lower covering can, for example, be a high-pressure spray tube as shown 76 , a so-called DuoCleaner 78 with a rotating cleaning head or a cleaning boot and a scraper 80 be assigned. In the event that a DuoCleaner with a cleaning boot is used as the DuoCleaner 78, the cleaning boot can be positioned above the lower covering 22nd stand still until a defined number of clothing revolutions has been reached. Then the cleaning boot is moved and by its working width across the lower covering 22nd drove on. After the entire width of the clothing has been cleaned in many steps, the DuoCleaner, which is equipped with a cleaning boot, moves continuously back to the opposite side of the machine at increased speed and is freed from adhering dirt particles there by a cleaning station. The cycle either starts again immediately afterwards or after a specified waiting time.

In the only figure is the bottom of the machine 10 with 82 and the basement or the zero level is designated by 84.

List of reference symbols

10

machine

12th

Wire section

14th

Press section

16

Dryer section

18th

last press nip, shoe press nip

20th

first dryer fabric

22nd

lower covering

24

Impingement drying section

24 '

Impingement dryer

28

Suction roll

30th

Back-up roll

32

stabilizer

34

second dryer fabric

36

Suction roll

38

another impingement drying section

38 '

another impingement dryer

42

Back-up roll

44

stabilizer

46

Shoe press roll

48

Counter roll

50

Steam box

52

first press nip

54

second press nip

56

upper press felt

58

central press roll

60

Counter roll

62

Counter roll

64

lower press felt

66

Forming fabric

68

Dryer screen

70

Drying group

72

Drying cylinder

74

Deflection suction roll

76

High pressure spray tube

78

DuoCleaner

80

scraper

82

floor

84

Basement, zero level

L.

Machine or web direction

Claims (15)

Machine (10) for producing or treating a fibrous web, in particular a paper or cardboard web, with a wire section (12), a press section (14) and a drying section (16), the fibrous web following the last press nip (18) of the press section (14) is taken over by a first circulating drying wire (20) of the drying section (16) from a rotating lower clothing (22) guided through the last press nip (18) of the press section (14) and together with the first drying wire (20) of the drying section (16) is guided generally vertically upwards along an impingement drying section (24), along which the underside of the fibrous web is dried by at least one impingement dryer (24 '). Machine after Claim 1 , characterized in that the lower covering (22) guided through the last press nip (18) of the press section (14) comprises a transfer belt. Machine after Claim 2 , characterized in that the transfer tape is impermeable to water. Machine after Claim 2 , characterized in that the transfer tape is permeable to water. Machine according to one of the preceding claims, characterized in that the fibrous web in the area of a suction guide roller (28) wrapped around by the first dryer wire (20) of the dryer section (16) is separated from the lower clothing (14) guided through the last press nip (18) of the press section (14). 22) is adopted. Machine according to one of the preceding claims, characterized in that the first drying wire (20) of the drying section (16) along the impingement drying section (24) on its side opposite the at least one impingement dryer (24 ') via support rollers (30) and / or with negative pressure acted upon stabilizers (32), in particular stabilizer boxes, is performed. Machine according to one of the preceding claims, characterized in that the fibrous web following the impingement drying section (24) of the first dryer wire (20) through a second circulating dryer wire (34) of the dryer section (16) in the area of one of the second dryer wires (34) of the The suction guide roll (36) wrapped around the dryer section (16) is taken over by the first dryer wire (20). Machine after Claim 7 , characterized in that the fibrous web is guided together with the second dryer wire (34) of the dryer section (16) along a further impingement drying section (38) along which the upper side of the fibrous web is dried by at least one further impingement dryer (38 '). Machine after Claim 8 , characterized in that the second drying wire (34) of the drying section (16) along the further impingement drying section (38) on its side opposite the at least one impingement dryer (38 ') via support rollers (42) and / or stabilizers (44) acted upon by negative pressure , in particular stabilizer boxes, is performed. Machine according to one of the preceding claims, characterized in that the last press nip (18) of the press section (14) in Web running direction (L) is extended, it is preferably formed by a shoe press nip. Machine after Claim 10 , characterized in that the shoe press nip (18) is formed between an overhead shoe press roll (46) and an underneath counter roll (48) of a shoe press wrapped around by the lower covering (22). Machine after Claim 11 , characterized in that the fibrous web guided together with the lower covering (22) around the counter roll (48) of the shoe press (46, 48) in the area of the counter roll (48) in front of the shoe press nip (18) by the steam of at least one steam blower box (50 ), in particular high-performance steam box, is acted upon. Machine according to one of the preceding claims, characterized in that the press section (14) comprises at least two further press nips (52, 54) in addition to the last press nip (18), with a central press roll (58) wrapped around by a circumferential upper press felt (56) ) to form a first press nip (52) and a second press nip (54) following it in the web running direction (L), two counter-rollers (60, 62) are assigned and the fibrous web is between the circumferential upper press felt (5) and a circumferential lower press felt (64) passed through the first press nip (52) and between the upper, circumferential press felt (56) surrounding the central press roll (58) and the circumferential lower covering (22) of the last press nip (18) of the press section (14) through the second press nip (54) is. Machine after Claim 13 , characterized in that a suction press roll is provided as the central press roll (58). Machine after one of the Claims 8 until 14th , characterized in that the fibrous web following the further impingement drying section (38) is taken over from the second drying wire (34) by a circulating drying wire (68) of an in particular single-row drying group (70).

Images