EP0428768A1 - Dryer section of machines for making webs of fibrous materials - Google Patents

Abstract

A drying section comprises a number of drying groups. Each of these has its own endless support band (171-175) which, together with the web, runs alternately over drying cylinders (101-138) and over guide rollers. In each drying group, at least some of the drying cylinders lie in an approximately vertically arranged cylinder row (161-168). In the first drying group (160/161), the web runs from the top to the bottom through a vertical cylinder row (161), the lower web side touching the cylinders. In the second drying group (162/163), the web runs first from the bottom to the top, the upper web side touching the cylinders. At least two drying groups have two vertical cylinder rows (162-167), the guide roller rows being arranged in one drying group on the outer sides and in the other drying group on the inner sides of the cylinder rows.

Description

The invention relates to a dryer section for a machine for the production of fibrous webs, e.g. Paper webs with a variety of heatable drying cylinders. The drying section is divided in a known manner into several drying cylinder groups ("drying groups"). Each of these dryer groups has its own endless support belt which runs together with the web to be dried over the drying cylinders and over guide rollers. The fibrous web comes into direct contact with the cylinders, while the support belt comes into direct contact with the guide rollers.

• 1. US-PS 3,868,780
• 2. Zeitschrift "Wochenblatt für Papierfabrikation" Nr.22, 1988, Seite 6.

More specifically, the invention relates to a dryer section in which, at least in a large part of the dryer groups, the drying cylinders are arranged in an at least approximately vertically arranged cylinder row. Dryer sections of this type are known from the following publications:

• 1. U.S. Patent 3,868,780
• 2. Magazine "Wochenblatt für Papierfabrikation" No. 22, 1988, page 6.

9 of document 1, each dryer group consists of only a single row of cylinders, and - as already mentioned - each dryer group has its own endless support belt. However, so-called two-row dryer groups are also known from other figures of the US patent mentioned.

For example, FIG. 2 shows a two-row dryer group with drying cylinders arranged vertically one above the other, the fibrous web to be dried first running through the first cylinder row from top to bottom and then through the second cylinder row from bottom to top. Naturally, only one of the two web sides can come into contact with the drying cylinders within such a two-row dryer group. In FIGS. 5 and 7, such a two-row dryer group is followed by a further two-row dryer group. In this second dryer group, the web runs first through the first row of cylinders from bottom to top and then through the second row of cylinders from top to bottom. As a result, the other web side comes into contact with the drying cylinders in this drying group, so that overall a uniform drying of the web can be achieved on both sides. It is disadvantageous in FIGS. 5 and 7 (and also in FIG. 8) that the two two-row drying groups are arranged offset in height from one another.

This disadvantage is avoided in the already mentioned FIG. 9 of document 1. The following is provided there: In the first dryer group, which has only a single row of cylinders, the fibrous web runs from top to bottom over the drying cylinders, one side of the web touching the drying cylinders. In a subsequent second drying group, which also has only a single row of cylinders, the fibrous web runs from bottom to top over the drying cylinders, the other side of the web touching the drying cylinders. This alternating guiding of the two web sides over the cylinders of one cylinder row is continued several times in FIG. A disadvantage of this arrangement is that in the first dryer group the upper web side comes into contact with the drying cylinders and that for this reason those guide rollers which feed the paper web directly to the subsequent drying cylinders are on the side of the drying cylinder row facing away from the press section . This is unfavorable because the paper web is torn off Broke broke off in the area of the mentioned guide rollers from the support belt and because the committee falls back onto the support belt at the bottom. This should be avoided especially on the first row of cylinders, because rejects are much more common in the first dryer group than in the following dryer groups. It is also disadvantageous that all dryer groups each have only a single row of cylinders. The number of dryer groups is therefore relatively high, including the number of support belts, tensioning rollers and regulating rollers.

In the arrangement according to document 2 an attempt was made to avoid these disadvantages. There, the fibrous web to be dried runs in the first dryer group from top to bottom through a vertical row of cylinders, the associated vertical guide roller row being on the side of the row of cylinders which faces the press section. In this series of cylinders, the lower web side always comes into contact with the drying cylinders. The main consequence of this arrangement, however, is that any committee that may be incurred can fall freely. In the direction of travel behind the bottom cylinder of the aforementioned vertical cylinder row, the web is transferred from the support belt of the first drying group to the support belt of the second drying group. The web in the second dryer group thus runs through a vertical row of cylinders from bottom to top, the upper web side now coming into contact with the drying cylinders. The two-row dryer groups then follow these two single-row dryer groups. Each of the transfers from one of these dryer groups to the subsequent dryer group is in turn designed in such a way that the other web side comes into contact with the cylinders in the subsequent dryer group. So that all two-row dryer groups are still at the same height, the guide roller rows are arranged in one dryer group on the outside of the cylinder rows and in the other dryer group on the inside of the cylinder rows.

This arrangement known from document 2 has the disadvantage, however, that in the two-row dryer group in which the guide roller rows are arranged on the inside of the cylinder rows (or in other words: between the cylinder rows) Paper web runs through the first row of cylinders from top to bottom and through the second row of cylinders from bottom to top. The result of this arrangement is that any rejects in this drying group cannot fall freely down to the floor of the machine building. It is conceivable to arrange a conveyor belt for the reject extending across the machine below the guide rollers of this dryer group. Nevertheless, there is a risk that any scrap paper that may be produced is wound up on one of the drying cylinders.

The invention is therefore based on the object of further developing the drying section known from document 2 in such a way that the removal of any rejects that may occur is simplified. In particular, the use of a conveyor belt located inside the machine should be avoided.

This object is achieved by the combination of the features of claim 1. After that, the entire dryer section is made up of single-row and two-row dryer groups, similar to document 2. An essential difference compared to document 2 is that in all two-row dryer groups the fibrous web runs from bottom to top through the first row of cylinders and from top to bottom through the second row of cylinders. At the same time, the feature already known from document 2 is retained, according to which, in successive two-row dryer groups, the guide roller rows are arranged in one dryer group on the outside of the cylinder rows and in the other dryer group on the inside of the cylinder rows. This maintains the advantage that alternately both sides of the web to be dried with the Come into contact with drying cylinders. The result of the arrangement according to the invention is that, at least on the two-row dryer groups, the transfer points, where the web to be dried is transferred from the support belt of a previous dryer group to the support belt of a subsequent dryer group, are arranged in the lower region, i.e. in the vicinity of the basement floor of the machine building are. Any committee that is now incurred can now fall down without difficulty in the entire dryer section. Where necessary, the transfer point can be opened if a reject occurs, namely by moving a guide roller, this can ensure that any rejects that may occur at the transfer points can also be discharged down to the basement floor of the machine building.

Further inventive ideas and advantageous refinements of the invention are specified in the subclaims. According to a particularly expedient arrangement is characterized in that the first dryer group has only a single vertical row of cylinders, and that the last dryer group also has only a single vertical row of cylinders (or three vertical rows of cylinders), and that finally in these two dryer groups always the bottom of the web to be dried comes into contact with the cylinders. One consequence of these features is that an odd number of medium drying groups must be provided between the first and the last drying group, all of which are preferably designed as two-row drying groups.

The advantage (compared to conventional dryer sections with only horizontal rows of cylinders) is retained that the length of the dryer section is relatively short (saving on construction costs for the building). This is particularly successful if all of the drying cylinders are arranged in vertical rows of cylinders, that is to say if, in particular in the first drying group, all of the cylinders are essentially in one vertical cylinder row are arranged. However, other considerations may be more important. For example, as is known from document 2, a single cylinder of a row of cylinders can be horizontally offset from the vertical row. It has also been found that it can be of great advantage if the first dryer group is composed of a first, essentially horizontal row of cylinders and an immediately following, essentially vertical row of cylinders, through which the web runs from top to bottom. A slightly increased overall length of the dryer section must be accepted. However, the following advantages outweigh this disadvantage: the broke pulper located below the press section can be extended in the direction of the drying section, and the scrap that may be generated on the first drying cylinders can thus be fed directly into the committee dissolver. In addition, space is created between the press section and the first vertical row of cylinders for auxiliary devices, pipes, etc.

The accompanying drawing shows a schematically illustrated embodiment of the invention.

The drying section shown comprises a first horizontal row of cylinders 160 and a total of eight series-connected, essentially vertical rows of drying cylinders 161-168. This dryer section is part of a paper manufacturing machine. The majority of the drying cylinders, namely the cylinders 105-138, are mounted on large stands, not shown, which stand directly on the basement floor 39 of a machine building. At the left end of the drawing, part of the press section 140 can be seen, which rests on a concrete foundation 141. This concrete foundation has an extension 141 ', on which the cylinders 101-104 of the horizontal row of cylinders 160 rest. At the right end of the drawing, part of a smoothing unit 150 following the drying section can be seen, which rests on a concrete foundation 151. On the top of the Concrete foundations 141 and 151 indicate the level of the paper machine floor with 48 and 49 respectively. So you can see that at least in most of the dryer section the usual concrete foundations (columns and longitudinal beams) are not available. It can also be seen that the arrangement of the majority of the drying cylinders 105-138 in vertical rows means that the longitudinal extent of the drying section is considerably less compared to the usual arrangement of the drying cylinders in a single horizontal cylinder row or in two superimposed horizontal cylinder rows.

The first dryer group, formed from the cylinder rows 160 and 161, has an endless support belt 171. This first runs over a suction guide roller 180, where the support belt takes over the web from the press section 140 by means of a paper guide roller 179 and feeds it to the first drying cylinder 101. From here, the support belt 171 and the fibrous web run together successively over further suction guide rollers 180 and 181 and the cylinders 102-107, the lower side of the web touching the cylinders. The web is transported from the bottom suction guide roller 181 towards the second dryer group 162/163 by means of the support belt 171.

In total, the dryer section shown comprises five dryer groups, each of which has its own support belt 171-175. The guide rollers for these support belts 171-175 are only shown schematically, a normal guide roller as a simple circle, a suction guide roller as a circle with a point and a tension roller as a circle with a simple arrow (e.g. 170). Some of the normal guide rollers (191 - 194) have a double arrow; this means that they are essentially horizontally displaceable, as will be explained below.

The two vertical cylinder rows 162 and 163 together form a two-row dryer group; ie the eight cylinders 108-115 have a common support belt 172. This guides the web to be dried, starting from a pick-up roller 182a first from bottom to top via cylinders 108-111 and then from top to bottom via cylinders 112-115. In this entire drying group, the upper web side always comes into contact with the cylinders.

Similarly, the two rows of cylinders 164 and 165 (together with an upper middle drying cylinder 120) form a further, likewise two-row drying group with a common support belt 173. This takes over the web by means of a pick-up roller 183a and guides it first from bottom to top via cylinders 116-120 and then from top to bottom via cylinders 120-124. Here, as in the first dryer group 160/161, the lower web side always comes into contact with the drying cylinders. This is followed by another drying group, which is formed from the two rows of cylinders 166 and 167 and has the support band 174. The structure of this dryer group is almost identical to the second dryer group 162/163; only the number of cylinders is two more. Finally, the last four drying cylinders 135-138 form a single-row dryer group 168 with the support belt 175 and with the pick-up roller 185a. Instead of the last single-row dryer group 168, a three-row dryer group could also be provided, in which the web runs first over the cylinders from bottom to top, then from top to bottom and finally from bottom to top.

In any case, the web runs free from the last cylinder 138 (ie without the support belt 175), for example, via a paper guide roller 176 into the smoothing unit 150. It is also important that in each case the web passes through the last drying cylinder row 168 from bottom to top and that the top drying cylinder 138 of this row is closer to the smoothing unit 150 than the other cylinders 135-137. This ensures that the completely dried web runs in the direction from top to bottom of the last cylinder 138. If the web now temporarily does not continue to the smoothing unit 150, it can fall freely and is forwarded via a sloping wall 177 into a reject dissolver, not shown.

In order to enable threading of an edge strip of the paper web (without the otherwise usual cable routing) when starting up the paper machine, also to keep the cylinder surfaces clean and to remove any scrap that may occur, a scraper 98 is arranged on each cylinder, as exemplarily on the Cylinders 101 to 103 and 138 shown. Below the press section 140 and below the three cylinders 101-103, one can see a broke pulper 196 with an inclined wall 197. This inclined wall 197 is arranged in such a way that the committee dissolver not only that in the press section 140, but can also directly accommodate the committee accruing on cylinders 101-103.

It is important that the web runs through all two-row dryer groups 162/163, 164/165 and 166/167 always first in the direction from bottom to top and then in the direction from top to bottom. As a result, all transfer points where the web changes from one support belt to the following support belt are arranged in the lower region of the dryer section. The following is provided in detail at these transfer points, explained using the example of the transfer from the first dryer group 160/161 to the second dryer group 162/163: from the bottom drying cylinder 107, the support belt 171 runs together with the web over the bottom suction guide roller 181 and from there approximately vertically up. Here, the support belt 171 touches the pick-up roller 182a of the subsequent drying group, so that the web runs from here to the next drying cylinder 108. On the further way up the support belt 171 runs over an approximately horizontally displaceable guide roller 191. It is shown with broken lines that by moving the guide roller 191 (to the left in the drawing) a distance a between the support belt 171 and the pick-up Roller 182a can be adjusted. This option will be used if there is scrap in the area of the drying cylinder 108-111 and down should be removed. The same transfer device is provided between the third dryer group 164/165 and the fourth dryer group 166/167, namely with a horizontally displaceable guide roller 193. The same transfer principle, but with support belts running from top to bottom, is realized at the transfer point between the second dryer group 162/163 and the third dryer group 164/165 and also at the transition point from the fourth dryer group 166/167 to the last dryer group 168. In these cases, the horizontally adjustable guide roller 192 or 194 rests on a common frame together with a tension roller 170 , exemplified at 169.

The transfer of the paper web from the press section 140 to the dryer section takes place, as already mentioned, by means of a paper guide roll 179 and the first suction guide roll 180. The distances between the paper guide roll 179 and suction guide roll 180 and between this and the first drying cylinder 101 are very short, so that the suction boxes required earlier within the loop of the first support belt can be dispensed with. The transfer facilities described above and located between the dryer groups have i.a. the advantage that, unlike document 2, there are no suction boxes required. There is also the advantage that no cable guide is required for threading the edge strip of the paper web into the dryer section. Thanks to the horizontally displaceable guide rollers 191-194, any rejects that may occur in the entire dryer section can be discharged down to the basement floor 39 of the machine hall without difficulty, without the need for a conveyor belt located inside the machine.

The cylinders 102-104 of the first dryer group and the associated suction guide rollers 180 'are with dash-dotted lines Lines shown. This illustrates that the embodiment shown in FIG. 2 can be modified by omitting these cylinders 102-104 and suction guide rollers 180 'and the foundation extension 141'. In this case, the first drying cylinder 101 would belong to the first vertical cylinder row 161, similarly to FIG. 1. Accordingly, the entire dryer section would be a little shorter.

Claims (8)

1. Drying section for a machine for producing fibrous webs, for example paper webs, with a large number of heatable drying cylinders (101-138) and with the following features: a) the dryer section comprises a plurality of dryer groups (drier groups), wherein a guide roller (181) is arranged between two drying cylinders (eg 101, 102); b) each dryer group has its own endless support belt (171-175) which, together with the fibrous web, runs alternately over the drying cylinders and over the guide rollers, so that the fibrous web comes into direct contact with the cylinders; c) in each drying group at least some of the drying cylinders are arranged in an at least approximately vertically arranged row of cylinders (161-168); d) in the first dryer group, which has only a single vertical row of cylinders (161), the fibrous web runs from top to bottom through the vertical row of cylinders (161), the lower side of the web touching the drying cylinders; e) there are at least two immediately successive two-row dryer groups (eg 162/163 and 164/165), the guide roller rows in one dryer group (162/163) being arranged on the outer sides of the cylinder rows, while the guide roller rows Rows in the other dryer group (164/165) are arranged on the inside of the cylinder rows, and in each of these two-row dryer groups the fibrous web through the first cylinder row (162, 164) from bottom to top and through the second cylinder row (163 , 165) runs from top to bottom. 2. Drying section according to claim 1, characterized in that the said two-tier dryer groups (162/163 and 164/165) immediately follow the first dryer group (161). 3. Drying section according to claim 1 or 2, characterized in that the last dryer group (168) is a single-row dryer group through which the fibrous web runs from bottom to top, the lower web side touching the drying cylinder (135-138). 4. Drying section according to claim 2 or 3, characterized in that in addition to the first and the last drying group there are only two-row drying groups (162/163; 164/165; 166/167), the fibrous web, in each of these drying groups, runs from bottom to top through the first row of cylinders and from top to bottom through the second row of cylinders 5. Drying section according to one of claims 1-4, characterized in that the first dryer group has a first, essentially horizontal cylinder row (160) and immediately thereafter a second, essentially vertical cylinder row (161), through which the fibrous web runs from top to bottom. 6. Drying section according to one of claims 1 to 5, characterized in that (in a manner known per se) each drying group following the first drying group (61) (eg 62; 63/64) has a suction guide roller (82a ; 83a), which is designed as a pick-up roller, the support belt (71, 72) of the preceding drying group affecting the pick-up roller. 7. Drying section according to claim 6, characterized in that the following is provided for the purpose of transferring the fibrous web from a preceding drying group (eg 160/161) to a subsequent drying group (162/163): a) from the last drying cylinder (107) of the preceding drying group, the support belt (171) runs together with the fibrous web over a last suction guide roller (181) and from this on a substantially vertical path to a substantially horizontally displaceable guide roller (191), the The pick-up roller (182a) of the following drying group is affected; b) by horizontally adjusting the displaceable guide roller (191), a distance (a) between the support belt (171) of the preceding drying group and the pick-up roller (182a) of the following drying group can be set. 8. Drying section according to claim 7, characterized in that the horizontally adjustable guide roller (194) and a tensioning roller rest on a common frame (169).

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