DE102010038875A1 - Apparatus and method for producing a material web - Google Patents

Abstract

The invention relates to a dryer section (1) of a machine for producing and / or finishing a paper, cardboard, tissue or other fibrous web (11), with several dryer groups (3, 4, 5), which drying cylinders (8, 8.1 , 8.2, 8.3) and deflecting rollers (6), the fibrous web (11) lying on a drying wire (9.1, 9.2, 9.3) in a meandering shape, alternating around the drying cylinders (8, 8.1, 8.2, 8.3) and around the deflecting rollers (6) is guided and touches the outer surface of the drying cylinder (8, 8.1, 8.2, 8.3). The drying section according to the invention is characterized in that at least one drying cylinder (8, 8.1, 8.2, 8.3) in at least one drying group (3, 4, 5) is free of machine-wide doctors (10.1, 10.3).

Description

The invention relates to a dryer section of a machine for producing and / or finishing a paper, board, tissue or another fibrous web, with a plurality of dryer groups, which comprise drying cylinders and guide rollers. The fibrous web is lying on a drying wire meandering alternately around the drying cylinder and guided around the guide rollers and touches the lateral surface of the drying cylinder.

The invention also relates to a method for operating a dryer section.

Drying sections of this type are known and are used for high-speed paper machines. The energy consumption in dryer sections is considerable, especially at high production speeds. In the context of current discussions on the subject of sustainability, both paper machine manufacturers and paper manufacturers strive to minimize the energy expenditure in the production process.

It is therefore the object of the invention to provide a solution for reducing the energy consumption and increasing the cost-effectiveness in the production and / or refinement of a paper, board, tissue or another fibrous web.

This object is solved by the features of claim 1 and the features of claim 12.

According to the invention, it is provided that in at least one drying group of the dryer section, for example a paper machine, at least one drying cylinder is free of machine-wide scrapers. The inventor has recognized, on the one hand, that the contact pressure of the machine-wide scrapers on the drying cylinder surfaces during paper production causes a proportion of 50% -70% of the drive energy of the dryer section. On the other hand, he has recognized that the use of machine-wide scrapers in the dryer section, depending on the existing boundary conditions, only at certain positions in the manufacturing process is advantageous and machine-wide scrapers can be eliminated at other positions. As a result, the drive energy of the drying cylinder can be significantly reduced. The invention also reduces investment costs by eliminating scrapers and smaller drive motors, in addition to saving energy.

In a practical embodiment, in the at least one dryer group ( 3 . 4 . 5 ) only the last drying cylinder ( 8.1 . 8.2 . 8.3 ) a machine-wide scraper ( 10.1 . 10.3 ). This is especially true in the event that the dryer group is the last of the dryer section.

It is also possible if the at least one dryer group ( 3 . 4 . 5 ) is free of machine-wide scrapers.

In a particularly advantageous embodiment, the at least one dryer group ( 3 . 4 . 5 ) in the dryer section ( 1 ) at a mean dry content of the fibrous web ( 11 ) of greater than 70%, in particular greater than 75%.

The at least one drying group is preferably arranged in the rear region of the drying section, pre-drying section or after-drying section, for example as last and / or as penultimate and / or as third-third drying group.

In a practical dryer section concept, the first two dryer sections may be equipped with machine-wide scrapers and one or more of the following dryer sections according to the invention, wherein at least one dryer cylinder of a dryer group is free of machine-wide scrapers. Thus, for example, at least 1/4, or at least 1/3, or at least half of the drying cylinders of a dryer section according to the invention can be designed without machine-wide scrapers.

Preferably, the at least one dryer group ( 3 . 4 . 5 ) as a single-row dryer group with overhead drying cylinders ( 8th . 8.1 . 8.2 . 8.3 ).

In a further embodiment variant, the drying section is completely single-row with overhead drying cylinders.

Conveniently, at least the pre-drying section is executed completely single-row with overhead drying cylinders.

The machine-wide scrapers ( 10.1 . 10.3 ) are preferably to the drying cylinder ( 8.1 . 8.2 . 8.3 ) executed on and swiveled.

According to another preferred practical embodiment, between the drying cylinders ( 8th . 8.1 . 8.2 . 8.3 ) and the guide rollers ( 6 ) Web stabilizers ( 7 ) for stabilizing the run of the fibrous web ( 11 ) by means of negative pressure, arranged. The guide rollers are evacuated via a connected vacuum system.

Some web stabilizers have negative pressure zones with respect to the fibrous web and preferably have in the region of detachment of the fibrous web from the drying cylinder surface a machine-wide acceptance zone, where the vacuum is more than 700 Pa. Advantageously, at least 3 web stabilizers have a machine-wide take-off zone, in particular at least 1/4, preferably at least 1/3 of the web stabilizers.

The web stabilizers following a drying cylinder without a scraper preferably have a machine-wide removal zone with a high underpressure of at least 700 Pa.

In a practical further development, tear-off sensors in the dryer section are for detecting breaks in the fibrous web ( 11 ) intended.

In a particularly advantageous variant, the tear-off sensors are designed as vacuum sensors and / or as optical sensors. As a result, a rapid detection of a tear of the fibrous web is possible.

In order to shorten the production downtime after a demolition, web take-off devices for targeted knocking off the fibrous web ( 11 ) intended. The web peeling devices are in operative connection with the tear sensors, so that when the fibrous web is torn off, it can be quickly knocked off at a preferred location, for example in the region of a broke container at the end of a transfer section. This avoids further production disruptions and delays.

Furthermore, it is possible that the at least one dryer group ( 3 . 4 . 5 ) of the dryer section has at least one tear-off sensor.

Advantageously, each dryer group is associated with a tear sensor with one or more dryer cylinders which are free of a machine wide scraper.

In a practical case, a tear-off sensor can be provided after every 5th to 6th drying cylinder.

For certain types of paper, a one-sided or two-sided application of a medium to the surfaces of the fibrous web, such as a glue application. For this purpose, the fibrous web is pre-dried to a certain dry content in a pre-drying section, the medium is applied and then further dried in the after-dryer section or finished.

The invention can also be used advantageously in a post-dryer section and / or a pre-dryer section.

It is expedient if at least six drying cylinders of a drying section or of an after-drying section and / or a pre-drying section are free from machine-wide scrapers.

To prepare the paper production, a narrow edge strip of the fibrous web is guided in sections through the various sections of the paper machine and then widened to the production width of the fibrous web. If a drying group forms the end of a transfer section, it is advantageous if the last drying cylinder of this dryer group is assigned a machine-wide scraper.

The transfer of an edge strip is advantageously carried out without the usual transfer ropes, that is by a ropeless transfer. This type of transfer is reliable tear-off and therefore particularly suitable in connection with the invention.

In a further embodiment, transfer scrapers are provided in the edge region of some or all of the drying cylinders, but in particular in the edge region of the drying cylinders of the dryer section, to which no machine-wide scraper is assigned. The transfer scrapers are preferably designed to swing up and down and are applied only during the transfer of the transfer strip to the drying cylinder. Once after the transfer operation of the transfer strip has been driven to the production width of the fibrous web, the transfer scraper are swung back. This can reduce the drive energy during paper production. The transfer scrapers are up to 1 m, in particular 0.5 m wide.

It can also be advantageous if below the machine-wide scraper on the last drying cylinder of a drying group a reject container is provided for collecting the resulting during Aufführ at the beginning of the production process or after a successful demolition or deduction of the fibrous web pulp web residues.

Another aspect of the invention relates to a method of operating a dryer section of a machine for making and / or finishing a paper, board, tissue or other fibrous web having a plurality of dryer sections comprising drying cylinders and guide rollers, the fibrous web being on a dryer fabric lying meandering alternately around the drying cylinder and guided around the guide rollers and thereby brought into contact with the lateral surface of the drying cylinder. According to the invention, it is provided that during the production operation in at least one drying group at least one Drying cylinder is kept free of touching, machine-wide scrapers.

Furthermore, it can be provided that in the at least one drying group the course of the fibrous web is monitored for a disturbance.

In a practical embodiment, a Bahnabschlageinrichtung is actuated for knocking off the fibrous web when a fault occurs.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings.

It shows the

Figure a preferred embodiment of a dryer section according to the invention in a schematic highly simplified representation;

In the figure, the last three drying groups 3 . 4 . 5 a drying section 1 a paper machine shown. This can also be a pre-drying or after-drying section. The drying screens 9.1 . 9.2 . 9.3 meander around the drying cylinders 8th . 8.1 . 8.2 . 8.3 and around the evacuated guide rollers 6 guided. Every dryer 9.1 . 9.2 . 9.3 forms together with the entwined drying cylinders 8th . 8.1 . 8.2 . 8.3 , the looped deflection rollers 6 and further associated units each have a drying group 3 . 4 . 5 , In the dryer groups shown in this example 3 . 4 . 5 These are single-tier dryer groups with overhead drying cylinders 8th . 8.1 . 8.2 . 8.3 , The guide rollers 6 are in one of the drying cylinders 8th . 8.1 . 8.2 . 8.3 lying horizontal plane arranged. The fibrous web 11 is on the respective drying wire 9.1 . 9.2 . 9.3 lying by the dryer groups 3 . 4 . 5 led, whereby the fibrous web 11 in direct contact with the surfaces of the heated drying cylinders 8th . 8.1 . 8.2 . 8.3 comes and is dried. In the area of the last drying cylinders 8.1 . 8.2 . 8.3 a drying group 3 . 4 . 5 the fibrous web is attached to the dryer fabric 8.2 . 8.3 the following drying group 4 . 5 to hand over. The dryer section is due to energetic reasons by a drying hood 2 enclosed. In this embodiment, the invention provides that in at least one drying group 3 . 4 . 5 the drying section, at least one drying cylinder is free of machine-wide scrapers. As a result, the drive energy of the drying cylinder can be significantly reduced. In the present example, only the last drying cylinders 8.1 . 8.3 the last and the third last drying group 5 . 3 a machine-wide scraper 10.3 . 10.2 assigned. All remaining drying cylinders 8th are free from machine-wide scrapers. All drying cylinders 8th the penultimate drying group 4 are also free of machine-wide scrapers. As a result, in addition to saving energy and investment costs by eliminating machine-wide scraper and smaller drive motors for the dryer groups 3 . 4 . 5 reduced. Under the machine-wide scraper 10.3 of the last drying cylinder 8.3 the last drying group 5 an unrepresented waste container is arranged. This last drying cylinder 8.3 forms the end of a transfer section, so that the transferred fibrous web strip and the residual fibrous web are controlled during the transfer process for a short time driven into the rejects container. The last three drying groups 3 . 4 . 5 in the dryer section 1 are at a mean dry content of the fibrous web 11 greater than 70%, in particular greater than 75%. In the present embodiment, the drying cylinders of the first two drying groups, not shown, are each assigned a machine-wide scraper. In this area, the fibrous web has a low dry content, whereby the adhesion to the surface of the drying cylinder is high. The machine-wide scraper 10.1 . 10.3 are preferably to the drying cylinders 8.1 . 8.2 . 8.3 designed to swing in and out. Between the drying cylinders 8th . 8.1 . 8.2 . 8.3 and the guide rollers 6 are web stabilizers 7 for stabilizing the run of the fibrous web 11 by means of negative pressure, arranged. The guide rollers 6 are drained via a connected vacuum system. The web stabilizers 7 with respect to the fibrous web 11 Vacuum zones on and have in the field of detachment of the fibrous web 11 from the drying cylinder surface, a machine-wide decrease zone, in which the negative pressure is more than 700 Pa. Every drying group 3 . 4 . 5 has a tear-off sensor, not shown. The tear-off sensors are designed as vacuum sensors. This will quickly detect a tear of the fibrous web 11 possible. There are also railway teeing devices for targeted knocking off the fibrous web ( 11 ) intended. The web peeling devices are in operative connection with the tear-off sensors, so that at a demolition of the fibrous web 11 this can be quickly knocked off at a preferred location, for example in the region of a reject container at the end of a transfer section. This avoids further production disruptions and delays. The transfer of an edge strip is done without the usual transfer ropes, that is by a ropeless transfer. This type of transfer is reliable, tear-off and therefore particularly suitable in connection with the invention.

LIST OF REFERENCE NUMBERS

1

drying section

2

Trockenhaube

3

drying group

4

penultimate drying group

5

last drying group

6

deflection rollers

7

web stabilizers

8th

drying cylinders

8.1

last drying cylinder of the dryer group

8.2

last drying cylinder of the penultimate drying group

8.3

last drying cylinder of the last drying group

9.1

dryer

9.2

Dry sieve of the penultimate drying group

9.3

Dry sieve of the last dryer group

10.1

scraper

10.3

Scraper of the last drying group

11

Fibrous web

Claims (15)

Drying section ( 1 ) of a machine for producing and / or finishing a paper, board, tissue or another fibrous web ( 11 ), with several drying groups ( 3 . 4 . 5 ), which drying cylinders ( 8th . 8.1 . 8.2 . 8.3 ) and guide rollers ( 6 ), wherein the fibrous web ( 11 ) on a drying wire ( 9.1 . 9.2 . 9.3 ) lying meandering alternately around the drying cylinders ( 8th . 8.1 . 8.2 . 8.3 ) and around the guide rollers ( 6 ) is guided and the lateral surface of the drying cylinder ( 8th . 8.1 . 8.2 . 8.3 ), characterized in that in at least one drying group ( 3 . 4 . 5 ) at least one drying cylinder ( 8th . 8.1 . 8.2 . 8.3 ) free from machine-wide scrapers ( 10.1 . 10.3 ). Drying section ( 1 ) according to claim 1, characterized in that in the at least one dryer group ( 3 . 4 . 5 ) only the last drying cylinder ( 8.1 . 8.2 . 8.3 ) a machine-wide scraper ( 10.1 . 10.3 ) assigned. Drying section ( 1 ) according to claim 1 or 2, characterized in that the at least one dryer group ( 3 . 4 . 5 ) is free of machine-wide scrapers. Drying section ( 1 ) according to one of the preceding claims, characterized in that the at least one dryer group ( 3 . 4 . 5 ) in the dryer section ( 1 ) at a mean dry content of the fibrous web ( 11 ) of greater than 70%, in particular greater than 75%. Drying section ( 1 ) according to one of the preceding claims, characterized in that the at least one dryer group ( 3 . 4 . 5 ) as a single-row dryer group with overhead drying cylinders ( 8th . 8.1 . 8.2 . 8.3 ) is executed. Drying section ( 1 ) according to one of the preceding claims, characterized in that the scrapers ( 10.1 . 10.3 ) machine width and / or to the drying cylinder ( 8.1 . 8.2 . 8.3 ) are executed on and swiveled. Drying section ( 1 ) according to one of the preceding claims, characterized in that between the drying cylinders ( 8th . 8.1 . 8.2 . 8.3 ) and the guide rollers ( 6 ) Web stabilizers ( 7 ) for stabilizing the run of the fibrous web ( 11 ) are arranged by means of negative pressure. Drying section ( 1 ) according to one of the preceding claims, characterized in that tearing sensors for detecting tears of the fibrous web ( 11 ) are provided. Drying section ( 1 ) according to claim 8, characterized in that the tear-off sensors are designed as vacuum sensors and / or as optical sensors. Drying section ( 1 ) according to claim 8, characterized in that Bahnabschlagvorrichtungen for knocking off the fibrous web ( 11 ) are provided and these are in operative connection with the breakaway sensors. Drying section ( 1 ) according to claim 8, characterized in that the at least one dryer group ( 3 . 4 . 5 ) has at least one tear-off sensor. Method for operating a dryer section ( 1 ) of a machine for producing and / or finishing a paper, board, tissue or another fibrous web ( 11 ), with several drying groups ( 3 . 4 . 5 ), which drying cylinders ( 8th . 8.1 . 8.2 . 8.3 ) and guide rollers ( 6 ), wherein the fibrous web ( 11 ) on a drying wire ( 9.1 . 9.2 . 9.3 ) lying meandering alternately around the drying cylinders ( 8th . 8.1 . 8.2 . 8.3 ) and around the guide rollers ( 6 ) and thereby in contact with the lateral surface of the drying cylinder ( 8th . 8.1 . 8.2 . 8.3 ), characterized in that during the production operation in at least one dryer group ( 3 . 4 . 5 ) at least one drying cylinder ( 8th . 8.1 . 8.2 . 8.3 ) free from touching machine width scrapers ( 10.1 . 10.3 ) is held. Method according to claim 12, characterized in that the at least one drying group ( 3 . 4 . 5 ) in the dryer section ( 1 ) at a mean dry content of the fibrous web ( 11 ) of greater than 70%, in particular greater than 75%. Method according to claim 12, characterized in that in the at least one dryer group ( 3 . 4 . 5 ) the course of the fibrous web ( 11 ) is monitored for a disturbance. A method according to claim 14, characterized in that when a fault occurs a Bahnabschlageinrichtung for knocking off the fibrous web ( 11 ) is pressed.

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