CN102301068A - Device for producing a material web - Google Patents

Abstract

The invention relates to a drying device (1) for drying a material web (100), in particular a paper, cardboard or tissue paper web, having an upper side (101) and a lower side (102). The drying device (1) comprises at least one first drying section (2) and a second drying section (3), wherein the first drying section (2) extends substantially linearly and has a first impingement hood (4) for applying hot drying agent directly to the upper side (101) of the web (100). The underside (102) of the material web (100) is provided with a first drying wire (20) for guiding the material web (100) through the first drying section (2). The second drying section (3) has a second impingement hood (8) for applying hot drying agent directly to the underside (102) of the web (100), wherein the upper side (101) of the web (100) is provided with a second drying wire (22) for guiding the web (100) through the second drying section (3), and the second drying wire (22) is guided over at least one support surface (103). The drying apparatus (1) according to the invention is characterized in that the at least one bearing surface (103) is designed to be air-permeable and low-pulsed.

Description

Equipment for manufacturing webs

The invention relates to a drying apparatus for drying a web, in particular a paper, board or tissue web, which has an upper side and a lower side. The drying system comprises at least one first drying section and a second drying section, wherein the first drying section extends substantially in a straight line and has a first impingement flow hood for applying hot drying agent directly to the upper side of the web. The underside of the web is here equipped with a first drying wire for guiding the web through the first drying section. The second drying section has a second impingement hood for applying hot desiccant directly to the underside of the web, wherein the upper side of the web is equipped with a second hood for guiding the web through the second drying section. The drying wire and the second drying wire are guided on at least one support surface.

运行。在此纸幅被施加热空气并且强化地干燥。这种高效干燥器的重要性和干燥份额随着速度的增加而逐渐增大。在纸幅在随后的具有干燥筒的干燥部中第一次开式牵引之前，为了使纸幅具有足够的强度并且不破裂，对于每种纸都需要具有一定的最小干重含量。由此使得为布设造纸机的干燥部，高效干燥区间的长度相比后续的具有干燥筒的传统干燥装置不断增加。These dryers are used in modern paper machines with higher production speeds. This high-efficiency dryer is based on the impingement flow principle

run. Here the paper web is applied with hot air and intensively dried. The importance and drying share of such efficient dryers gradually increases with increasing speed. A certain minimum dry weight content is required for each paper in order for the paper web to have sufficient strength and not to break before the paper web is drawn open for the first time in the subsequent dryer section with the drying cylinder. As a result, for laying out the drying section of the paper machine, the length of the high-efficiency drying section is continuously increased compared to subsequent conventional drying devices with drying cylinders.

A drying device of the type according to the invention is described in German patent document DE 10 2007 018 378 A1. After the press section, the upper side of the web is dried in a horizontally extending impingement dryer and is then transferred (for drying the underside of the web) to a vertically arranged impingement dryer. The paper web is supported by drums in two impingement dryers.

In these known installations, the drying capacity required for increased machine speed can be increased by lengthening the impingement flow interval of the first high-efficiency dryer level. A disadvantage, however, is that the web runability decreases at higher machine speeds. This is especially true in the second drying section in which the underside of the paper web is dried in the impingement flow dryer. Each drying wire is supported by drums in the first and second drying sections. As a result, progressively narrowing and widening gaps are created between the drying wire and the drum at the individual drums. This leads to pressure pulses which cause the web to detach from the drying wire, especially at the edges. This can lead to web tears and wrinkles, especially at higher speeds.

Therefore, the technical problem to be solved by the present invention is to provide a drying plant which enables intensive and efficient drying and which has the ability to flexibly and economically match the drying capacity to the production requirements, while ensuring that the paper web is dry at high speeds. Has improved, reliable operating capabilities.

This technical problem is solved by the features of claim 1 . The drying apparatus is designed for drying a web having an upper side and an underside, in particular a paper, cardboard or tissue web. The drying apparatus comprises at least one first drying section and a second drying section, wherein the first drying section extends substantially in a straight line and has a first impingement flow hood for applying hot drying agent directly to the upper side of the web. The underside of the web is here equipped with a first drying wire for guiding the web through the first drying section. The second drying section has a second impingement flow hood for applying hot desiccant directly to the underside of the web, wherein the upper side of the web is provided with a first hood for guiding the web through the second drying section. Two drying wires, and the second drying wire is guided on at least one support surface. The solution according to the invention is characterized in that the at least one bearing surface is designed to be air-permeable and low-pulse.

The solution according to the invention achieves that the underside of the paper web rests securely against the drying wire even at higher speeds. This is especially advantageous when drying with an impingement dryer, in which the web is not guided between two drying wires, so that hot drying agent can be sprayed directly on the underside of the web and thus effectively dry the underside. Due to the low-pulse design of the support surface of the drying wire, there are no pressure pulses that cause the web to fall off the drying wire. The air-permeable support surface provides the possibility of suctioning the support surface and thus fixing the web more firmly on the drying wire. This is especially important when drying the underside of the web in order to fix the web on the drying wire against the force of gravity.

Hot air and/or steam can be used as desiccant.

The invention produces particularly advantageous effects at speeds of greater than 1700 m/min, especially greater than 1800 m/min.

Through the linear arrangement of the first drying section, the drying capacity can be flexibly adapted to production needs in its design by adapting the length of the first drying section. This makes it possible to achieve longer drying intervals compared to impingement flow drying devices which cannot be arbitrarily large on support rolls or support drums. A "straight line" is understood according to the invention to mean the straight and/or slightly curved course of the drying section. A slightly curved course has the advantage of better stabilizing the web on the drying wire. The radius of curvature is here greater than 10 meters, preferably greater than 15 meters.

In an advantageous refinement of the invention, at least one bearing surface is sucked off. A low negative pressure is sufficient here. The negative pressure can be in the range of 1 hPa to 200 hPa, especially in the range of 1 hPa to 100 hPa.

According to the invention, the first drying section can also be designed with a supporting surface corresponding to the supporting surface of the second drying section.

The bearing surface advantageously has perforations or bores or perforations. This simultaneously achieves a good support of the web and a low-pulse stability.

In another low-pulse embodiment, the support surface is designed as a stationary plate that is flat and/or curved in the direction of web travel. This design is inexpensive to manufacture.

In another, preferably practical, low-pulse embodiment, the support surface of the second drying section is formed by the sleeve of the support roll. Compared to the plates described, this solution has the advantage that no relative movement occurs between the drying wire and the support surface and thus no wear due to friction. The backing roll has a perforated, for example perforated, roll shell. A diameter in the range of 3 meters to 6 meters is sufficient to provide sufficient drying capacity.

In another practical embodiment, the inner surface of the backup roll sleeve is equipped with a suction box at least in the partial area surrounded by the second drying wire, wherein the sealing plate at the beginning of the suction box is placed upstream. Winding wire for the web. This prevents pressure pulses generated by the sealing disc from lifting the web off the drying wire and thus causing runnability problems. The suction box can be divided into several sections with different pressures viewed along the web running direction.

Preferably, a second drying section follows the first drying section, in which the web is transferred from the first drying wire to the second drying wire by means of a suction zone arranged in the second drying wire.

In a practical variant, the first impingement flow shield and/or the second impingement flow shield are formed by a plurality of partial shields along the running direction and/or transverse direction of the web.

Advantageously, the drying efficiency of the first impingement flow hood and/or the second impingement flow hood can be adjusted or adjusted in sections in the web running direction and/or transversely.

In a practical embodiment, the first drying wire is also guided on at least one air-permeable and low-pulse supporting surface corresponding to the supporting surface of the second drying wire.

In another aspect, the invention relates to a paper machine for producing a web, especially a paper, board or tissue web, comprising a press section and a drying section, wherein the drying section comprises at least one drying equipment.

In a preferred embodiment, a press section consisting of at least one extended press nip is upstream of the drying device according to the invention. This press section is also called a single NipcoFlex press. For certain kinds of paper it is also conceivable to use a press section consisting of two extended press nips arranged in succession. This press section is called a tandem Nipcoflex press. These extended press nips are preferably each formed by shoe rolls with counter rolls, wherein the paper web is guided through these press nips between two belts. The two straps can consist of two felts or also a felt and a smooth air-permeable or air-impermeable strap.

In a further embodiment of the invention, for those paper types which place high demands on surface roughness, such as supercalendered papers, with at least one extended press nip and calendering equipment arranged behind it The press section is placed in front of the drying equipment. The calendering apparatus consists of a drum and/or a belt with a smooth surface and a suctioned counter-roll. Here, the web is transferred from the smooth-surfaced lower clothing of the last press nip to a conveyor belt and from there to an air-permeable clothing that wraps around counter-rolls and is guided through the calendering zone of the calendering plant .

In another preferred embodiment of the paper machine, the press section with the compact press section and the downstream calendering installation is upstream of the drying installation. The calendering apparatus consists of drums and/or belts with smooth surfaces and suctioned counter-rolls. Here, the web is transferred from a central belt with a smooth surface surrounding the central roll to a conveyor belt and from there to an air-permeable clothing which surrounds the calender pair of rolls and guides the calender through the calender district.

In another preferred embodiment, the web is guided through the press section and through the drying device with a closed draw.

In addition to achieving a stable web run during production operation, the solution according to the invention also allows a wider transfer of the paper web after tearing or when the paper machine is put into operation again. This can only be achieved reliably with a low-pulsation bearing surface.

Additional features and advantages of the invention emerge from the following description of preferred embodiments with reference to the drawings. In the attached picture:

Figure 1 is a first embodiment of a paper machine with a drying installation according to the invention, which has an upstream press section,

Figure 2 is a second embodiment of a paper machine with a drying device according to the invention, which has an upstream press section with a calendering device,

FIG. 3 shows a third embodiment of a paper machine with a drying installation according to the invention, which has an upstream press section with a calender.

FIG. 1 shows an embodiment of a paper machine drying installation 1 . The drying device consists of a slightly curved first drying section 2 and a directly adjoining second drying section 3 . The paper web 100 is transferred from the transfer belt 30 in the area of the suction roll 5 onto the drying wire 20 . The drying wire 20 is supported by guide rollers 6 in the region of the first drying section 2 . The arrangement of guide rollers 6 forms a polygonal traction path corresponding to a radius of 15 meters. The paper web 100 is thus reliably guided. The upper side 101 of the paper web 100 is bare and not covered by another wire. Therefore, the hot desiccant ejected from the impingement flow shield 4 can reach the paper surface 101 without hindrance. At the end of the first drying section 2 the paper web 100 and the first drying wire 20 are guided around a suction roll 7 . In the next run, the web 100 is transferred to the second drying wire 22 . Suction elements are arranged in the transfer area to transfer the paper web 100 from the first drying wire 20 to the second drying wire 22 . The suction element can also be realized by a suction zone in the support drum 10 . The second drying wire 22 partially surrounds the support drum 10 , the steam-heated drying drum 11 , the suction deflection roll 12 and the further drying drum 13 . On this drying drum 13 , a second drying wire 22 is separated from the paper web and is led back via guide rolls 9 . The web is drawn to the next drying section by an open draw. The support drum 10 has a perforated drum jacket surface 103 which is sucked by suction boxes in the area surrounding the second drying wire 22 . The underside 102 of the web 100 is exposed and not covered by another wire. Therefore, the hot desiccant ejected from the impingement flow shield 8 can reach the paper surface 101 without hindrance. The impingement flow shield 8 is divided into two parts in this embodiment. However, a one-piece design structure is also possible. Air volume flow and temperature can be adjusted individually in each section. In the event of a tear in the paper web 100, the two hood parts 8 can be opened so that paper residues can be dropped into the mechanical stack for cleaning. To prevent the web run on the support cylinder 10 from becoming unstable due to gravity, the negative pressure in the suction box of the support cylinder 10 is 40 hpa.

The drying device 1 is preceded by a press section 200 . The paper web 100 is transferred from the forming zone onto the upper felt 50 of the first press nip and is co-guided with another felt 51 through the shoe nip 201 . The shoe nip is composed of a shoe roll 52 and a counter roll 53 . In the following operation, the paper web is unloaded from the lower felt 51 of the first press nip 201 by means of the upper felt 40 and by means of the suction roll 44 and guided through the second shoe nip 202 . Subsequently, the paper web 100 is unloaded from the lower belt 41 of the second nip 202 by the transfer belt 30 and transferred to the drying apparatus 1 .

The paper machine in FIG. 2 differs from the paper machine shown in FIG. 1 only in the design of the press section 205 . The press section 205 consists only of an extended press nip 203 and a downstream calender 300 . The paper web is discharged from the forming wire 500 by the upper felt 40 of the press nip 203 , which consists of a shoe roll 42 and a counter roll 43 , and is guided through the press nip 203 . The web is then conveyed to a calendering apparatus 300 via a conveyor belt 304 . The calendering unit consists of a suctioned counter roll 302 surrounded by an air-permeable fine felt 303 and a smooth calender roll 301 . The calender roll calenders the upper side 101 of the paper web.

FIG. 3 shows the drying installation 1 according to the invention in combination with a further variant of the press section 206 . The press section 206 consists of a so-called compact press section 400 with three press nips and a calendering apparatus 300 similar to FIG. 2 . The compact press section 400 produces a double-sided web 100 in terms of web smoothness. After pressing, the upper side 101 is rougher than the lower side 102 . This difference in roughness is compensated by calendering of the upper side 101 in the subsequent calendering plant 300 .

list of reference signs

1 drying equipment

2 The first drying section

3 Second drying section

4 First impingement flow shield

5, 7 suction roller

6 guide rollers

8 Second impingement flow shield

9 guide roller

10 support roller

11 drying drum

12, 13 steering roller

14 Format running direction

20 The first drying net

22 second drying net

30 conveyor belt

31 suction roller

40, 50 felt

41 pressure belt

42, 52 shoe roller

43, 53 pairs of rollers

44 suction roller

54 suction roller

100 material web, paper web

101 The upper side of the material web and paper web

102 Underside of material web, paper web

103 bearing surface

200 Press section

205, 206 press section

201, 202 extended press nip

203 Extended press nip

300 calendering equipment

301 calender roller

302 suction rollers

303 breathable belt

304 conveyor belt

400 compact press section

401 suction roller

402 pressure roller

403 shoe press roller

404 center roll

405 lower felt

406 center belt

407 Pick up Felt

500 forming wire

Claims (15)

1. A drying apparatus (1) for drying a web (100), especially a paper, board or tissue web, the web (100) having an upper side (101) and a lower side (102), The drying plant (1) comprises at least one first drying section (2) and a second drying section (3), wherein the first drying section (2) extends substantially in a straight line and has a The upper side (101) of (100) applies a first impingement flow hood (4) of hot desiccant, wherein the lower side (102) of the web (100) is equipped with a device for guiding the web (100) A first drying wire (20) leading through said first drying section (2), said second drying section (3) having a device for directly applying heat to the underside (102) of said web (100) A second impingement flow hood (8) for the desiccant, wherein the upper side (101) of the web (100) is equipped with a device for guiding the web (100) through the second drying section ( 3) the second drying wire (22), and wherein the second drying wire (22) is guided on at least one support surface (103), characterized in that the at least one support surface (103) is designed as Breathable and low-pulse. 2. Drying apparatus (1) according to claim 1, characterized in that the support surface (103) is suctioned. 3. The drying device (1) according to claim 1, characterized in that the support surface (103) has perforations or drilled holes or perforations. 4. The drying plant (1) according to one of claims 1 to 3, characterized in that the support surface (103) is designed as a stationary, flat and/or curved plate in the web running direction (14) . 5. The drying apparatus (1) as claimed in one of claims 1 to 4, characterized in that the bearing surface (103) is formed by a roller sleeve of a bearing roller (10). 6. The drying equipment (1) as claimed in claim 5, characterized in that, the inner surface of the roller sleeve of the support roll (10) is at least configured in the partial area surrounded by the second drying wire (22). There is a suction box, wherein a sealing sheet at the beginning of the suction box is placed before the winding line of the web (100). 7. The drying apparatus (1) according to claim 1, characterized in that, the second drying section (3) is immediately after the first drying section (2). 8. The drying device (1) according to claim 1, characterized in that, the first impingement flow cover (4) and/or the second impingement flow cover (8) is along the web running direction (14) and/or The horizontal direction is composed of multiple sub-hoods. 9. The drying device (1) according to one of claims 1 to 8, characterized in that, the drying efficiency of the first impingement flow hood (4) and/or the second impingement flow hood (8) runs along the web The direction ( 14 ) and/or transverse direction can be adjusted or adjusted in sections. 10. The drying equipment (1) according to claim 1, characterized in that, said first drying wire (20) is air-permeable and low-pulse, especially according to one of claims 2, 3, 4. guide on the bearing surface described above. 11. A paper machine for producing a web (100), especially a paper, board or tissue web, comprising a press section (200) and a dryer section, characterized in that the dryer section comprises At least one drying plant (1) according to one of claims 1 to 10. 12. The paper machine according to claim 11, characterized in that a press section (200) consisting of at least one elongated press nip (201, 202) is placed before the drying apparatus (1 ). 13. The paper machine according to claim 11, characterized in that a press section (200) with at least one elongated press nip (203) and a calender (300) arranged behind it is placed in the drying device(1) before. 14. The paper machine according to claim 11, characterized in that the press section (200) with the compact press section (400) and the calendering equipment (300) arranged thereafter is placed in the drying equipment (1) Before. 15. The paper machine as claimed in one of claims 11 to 14, characterized in that the web (100) is guided with closed traction through the press section (200) and through the drying device (1 ).

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