Method and apparatus for improving drying process in a paper machine

Abstract

The invention relates to a method for improving the efficiency of the drying process in a paper machine by means of a process control system when manufacturing a fibrous web, for drying purposes the fibrous web being guided in at least one drying group in a meandering, alternating manner through a plurality of steam-heated drying cylinders and a plurality of dryer felts, and between these steam-heated drying cylinders there are provided web stabilizers, which each have a removal device loaded with underpressure and a stabilizing device loaded with underpressure, the stabilizing device serving to stabilize the fibrous web removed from the respective drying cylinder by means of the removal device and also to stabilize the run of the fibrous web past the stabilizing device. The method according to the invention is characterized in that a plurality of web stabilizers are equipped with at least two sensors for measuring operating parameters, the measured operating parameters are jointly analyzed in a computing unit with the process data of the process control system, and the resulting control signals are used to optimize the drying process.

Description

Technical Field

[0001] This invention relates to a method for improving the efficiency of the drying process in a paper machine by means of a process control system during the manufacture of fiber webs. For drying, the fiber web, together with a permeable dry wire, is zigzag-guided alternately through multiple steam-heated drying cylinders and multiple dry wire suction rolls in at least one drying unit. A web stabilizer is provided between these steam-heated drying cylinders, each having a negatively pressured removal device and a negatively pressured stabilizing device. The stabilizing device stabilizes the fiber web removed from the respective drying cylinder by the removal device and also stabilizes the fiber web as it passes through the stabilizing device until it reaches the subsequent negatively pressured dry wire suction rolls. Preferably, two overpressure chambers are provided to form the sides of an air knife. Background Technology

[0002] This type of equipment is known. Document DE 102019124500 A1 discloses an apparatus for drying fiber webs used in the manufacture or finishing of fiber webs. The apparatus includes two drying cylinders, which, together with guide rollers, form a hopper. Within this hopper, the drying cylinders are equipped with removal devices for removing the fiber webs from the drying cylinders at removal points. The removal devices have a negative pressure space in the area of ​​the removal point, and this negative pressure space has seals of machine width at both the inlet and outlet of the fiber web, viewed from the direction of fiber web travel. Furthermore, a stabilization zone following the negative pressure zone is disclosed, which can also be placed in a vacuum. The negative pressure of this negative pressure space can be adjusted and controlled separately from the vacuum of the stabilization zone.

[0003] These known devices have different drawbacks. Various variable and disruptive effects can occur during paper machine operation. The drying process must be designed to operate well, to a greater or lesser extent. Therefore, the type of paper produced, the operating speed, the type of material, etc., may vary. The drying process must operate at the high productivity of the paper machine with as little risk as possible of web breakage or damage that could lead to failures in further processing of the fiber web. However, this is not always possible. For example, to maintain a stable drying process, the speed of the paper machine must often be reduced. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a method and apparatus to optimize the efficiency of the drying process and reduce or avoid known disadvantages.

[0005] The technical problem described herein is solved by a method for improving the efficiency of the drying process in a paper machine through a process control system during the manufacture of fiber webs. A method is proposed for improving the efficiency of the drying process in a paper machine through a process control system during the manufacture of fiber webs, wherein, for drying, the fiber web, together with a permeable dry wire, is zigzag-guided alternately through multiple steam-heated drying cylinders and multiple dry wire suction rolls in at least one drying unit, and a web stabilizer is provided between these steam-heated drying cylinders. The web stabilizer has a negative pressure removal device and a negative pressure stabilizing device, which stabilizes the fiber web removed from the corresponding drying cylinder by the removal device and also stabilizes the fiber web through the stabilizing device until the subsequent negative pressure dry wire suction rolls. Preferably, two overpressure chambers are provided to form the sides of the air knife.

[0006] Its features are,

[0007] a) Each of the multiple web stabilizers is equipped with at least two sensors for measuring operating parameters, and the subsequent dry web suction roller is preferably equipped with sensors for measuring operating parameters.

[0008] b) A computing unit is provided, and

[0009] c) The computing unit is connected to the process control system of the paper machine, and

[0010] d) The measured operating parameters are analyzed together with the process data of the process control system in the calculation unit, and control signals are output to multiple actuators effectively connected to the material width stabilizer.

[0011] e) Control multiple actuators of multiple material width stabilizers through the control signal.

[0012] This invention enables the optimization of the drying process in terms of drying and drying process, as well as the operability of the fiber web, by analyzing process data of the paper machine, such as machine speed and / or the unit area weight of the fiber web and / or the pulp composition in the calculation unit, together with the operating parameters of the web stabilizers and / or drying cylinders, and sending new control signals to the actuators of multiple web stabilizers to selectively influence the operating parameters. By considering the operating parameters of multiple web stabilizers simultaneously or at least at time intervals, effects that influence the drying process or operating characteristics of the fiber web, for example, by changing machine speed and / or the unit area weight of the fiber web and / or the pulp composition, can also be taken into account. Relatedly, for example, the tendency of the fiber web to stick together, which is not easily perceived immediately by the operator. If the effects of different pulp feed rates on the fiber web running capacity of different paper types are compared, the sticking tendency of the first paper type in multiple drying cylinders may be higher than that of the second paper type. According to the invention, the higher sticking effect can be offset by increasing the negative pressure in the removal and stabilizing devices, thereby avoiding fiber web breakage or machine speed reduction. Lowering the negative pressure when the adhesion effect weakens can also be considered. This predictive operating method enables higher paper machine productivity. The removal device has a negative pressure space, also known as a negative pressure chamber, in the area of ​​the removal point. Viewed from the direction of fiber web movement, this negative pressure space has machine-width seals at the fiber web's inlet and outlet. In this area, the fiber web is in direct contact with the dryer cylinder and is pressed against it by the dry wire. Two machine-width seals seal the negative pressure space relative to the dry wire. Therefore, during operation, clumping may cause the dry wire to come into contact with the seals. Consequently, these seals will wear and therefore must be adjusted or replaced from time to time. Pre-adjustment advantageously improves operational productivity and allows for predictive and efficient planning of replacements for upcoming maintenance.

[0013] To laterally seal the corresponding negative pressure chambers of the removal and stabilizing devices, air knives (not shown) can be provided on both sides, namely the edges of the guide side and the drive side of the first and second web stabilizers. These air knives are connected to overpressurized air chambers that generate air jets deflected by the Coanda effect. Air knives for sealing the space relative to a moving wall, in the current case, a moving dry-net space, are known and constitute an air curtain. Mechanical seals can also be used instead of air knives.

[0014] In a feasible extended design, multiple material spread stabilizers are each equipped with multiple independent actuators. For example, each material spread stabilizer can be equipped with an exhaust fan or a throttling element to generate or affect negative pressure in the removal device and / or stabilizing device.

[0015] In practice, these independent actuators can be controlled by multiple independent control signals. This achieves particularly good optimization of the drying process.

[0016] Another option is to group multiple actuators together for control purposes. The actuators in the group are controlled by the same control signal.

[0017] Another feasible approach is to combine multiple material width stabilizers into a material width stabilizer group in order to optimize the drying process.

[0018] In an advantageous practical design, the negative pressure in the removal device and / or the negative pressure in the stabilizing device and / or the negative pressure in each dry web suction roller is generated by at least one exhaust fan, which is directly or indirectly connected to the removal device and / or the stabilizing device and / or the subsequent dry web suction roller via piping.

[0019] In one feasible extended design, at least one exhaust fan is driven by a motor with controllable speed, and / or the piping is equipped with at least one controllable throttling element.

[0020] Preferably, the motor and / or the throttling element can be used as an actuator.

[0021] At least two sensors of the material width stabilizer are selected from the group consisting of a pressure sensor, a displacement sensor, a position sensor, and a wear sensor.

[0022] In addition to other process data, at least two sensors and actuators continuously provide operating parameters or data to the process control system.

[0023] Data from at least two sensors and / or actuator settings, preferably independent actuators, combined with process data, allows for the derivation of different developments or trends in process parameters based on operational variations. For example, the data can be used to identify early material width rise and / or adhesion, which can be offset by reducing and / or increasing the negative pressure in the material width stabilizer. Furthermore, subsequent material width stabilizers can be pre-controlled based on previous data. This ensures continuous optimization and monitoring.

[0024] The identified data can also be advantageously used for proactive maintenance of included components without the need for additional sensors. Changes recorded during operation can advantageously determine trends through implemented and / or autonomous learning algorithms, and output to operators as an indication of the next maintenance to be performed. For example, the wear condition of seals can be advantageously determined from sensor and / or actuator data combined with known process data. For example, data from pressure sensors and / or vacuum actuators can be used to determine seal wear.

[0025] At least two sensors are preferably pressure sensors.

[0026] At least two sensors may also include displacement sensors to measure, for example, the wear of the seals. Information from the wear sensor can be used to adjust for negative pressure in the negative pressure space, thereby avoiding negative consequences for the drying process.

[0027] However, it is also feasible to design at least two sensors as velocity sensors or sensors used to determine the volumetric flow rate of air used to generate negative pressure.

[0028] In a favorable extended design, process data are selected from a group consisting of the unit area weight of the fiber web, machine speed, dry web tension, steam pressure in the drying cylinder, and dry content of the fiber web in the regions of each web stabilizer.

[0029] The removal point from the dryer cylinder surface is particularly critical for the runnability of the fiber web, as the fiber web tends to adhere to the cylinder surface to varying degrees depending on operating conditions. This adhesion tendency depends, for example, on the pulp feed rate, paper machine speed, fiber web area weight, and dry content. Therefore, the adhesion tendency changes over time and during the drying process. For this reason, it is also advantageous to measure and, if necessary, influence the operating parameters at least in at least two time-staggered stages of the fiber web manufacturing process. This is achieved by optimizing the drying process using the operating parameters of multiple, at least two, web stabilizers.

[0030] For example, three, four, or five paper width stabilizers can be used to optimize the drying process.

[0031] Therefore, the present invention can also be adapted to individual drying units or even the entire drying section.

[0032] In a potentially advantageous scenario, the computing unit may be equipped with an autonomous learning algorithm for determining control signals in order to optimize the efficiency of the drying process.

[0033] The aforementioned technical problem is further solved by an apparatus for improving the efficiency of the drying process in a paper machine through a process control system during the manufacture of fiber webs. This apparatus is particularly designed for implementing the method according to the invention, in which, for drying, the fiber web, together with a permeable dry wire, is zigzag-intermittently guided through multiple steam-heated drying cylinders and multiple dry wire suction rolls in at least one drying unit. Between these steam-heated drying cylinders are web stabilizers, each having a negatively pressured removal device and a negatively pressured stabilizing device. The stabilizing device stabilizes the fiber web removed from the corresponding drying cylinder by the removal device and also stabilizes the fiber web as it passes through the stabilizing device until it reaches the subsequent negatively pressured dry wire suction rolls. Preferably, two overpressure chambers are provided to form the sides of the air knife.

[0034] Its features are,

[0035] a) Each of the multiple web stabilizers is equipped with at least two sensors for measuring operating parameters, and the subsequent dry web suction roller is preferably equipped with sensors for measuring operating parameters.

[0036] b) A computing unit is provided, and

[0037] c) The computing unit is connected to the process control system of the paper machine, and

[0038] d) The measured operating parameters are analyzed together with the process data of the process control system in the calculation unit, and control signals are output to multiple actuators effectively connected to the material width stabilizer.

[0039] e) Control multiple actuators of multiple material width stabilizers through the control signal.

[0040] The present invention is also explicitly extended to embodiments given by combinations of features not explicitly mentioned in the specification, and thus the disclosed features of the present invention can be arbitrarily combined with each other as long as they are technically reasonable. Attached Figure Description

[0041] Other features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings.

[0042] The only accompanying drawing shows a portion of the drying section of the paper machine in a schematic cross-section. Detailed Implementation

[0043] In this example, drying process 2 includes equipment 1 with a single row of drying units having three steam-heated drying cylinders 4.1, 4.2, and 4.3 in a horizontal plane. Fiber web 3, together with dry wire 6, is guided alternately and zigzagly through the drying cylinders 4.1, 4.2, 4.3 and the dry wire suction roll 5. The fiber web 3 is in direct contact with the heated drum surfaces of the drying cylinders 4.1, 4.2, and 4.3. The dry wire suction roll 5 has a perforated cover, which may have its own negative pressure interface via a journal, or, as in this case, be held in place by web stabilizers 7 and 8 through the perforated cover. In the region of the dry wire suction roll 5, the dry wire 6 is located between the perforated cover and the fiber web 3. The negative pressure in the dry wire suction roll 5 ensures that the fiber web 3 does not break when the paper machine is operating at high speeds or with insufficient pulp feed. As illustrated in the diagram, the drying cylinders 4.1, 4.2, 4.3 and the dry web suction roller 5 form pockets between adjacent drying cylinders 4.1, 4.2, 4.3 and the associated dry web suction roller 5. A web stabilizer 7, 8 is installed in each pocket to stabilize the web's movement. The first web stabilizer 7 and the second web stabilizer 8 are constructed identically. They have removal devices 7.1, 8.1 and stabilizing devices 7.2, 8.2. The removal devices 7.1, 8.1 have negative pressure chambers 7.5, 8.5, which are sealed relative to the dry web 6 along the running direction 15 by seals 7.6, 7.7, 8.6, 8.7 having a machine width. The negative pressure chambers 7.5 and 8.5 are arranged relative to the surface of the fiber web 3 away from the drying cylinders 4.1 and 4.2. This is a particularly critical location for the runnability of the fiber web 3, as the fiber web 3 tends to adhere more or less to the roller surface depending on the operating conditions. The tendency to stick depends, for example, on the pulp feed rate, the speed of the paper machine, the area weight per unit area of ​​the fiber web 3, and the dry content. Therefore, the tendency to stick changes over time and during the drying process. The negative pressure chambers 7.5 and 8.5 of the removal devices 7.1 and 8.1 are connected via conduit 16 to an exhaust fan 12 driven by a speed-controlled drive motor to generate negative pressure. The fiber web stabilizers 7 and 8 also have stabilizing devices 7.2 and 8.2 loaded with negative pressure, which are used to stabilize the fiber web 3 on the dry wire 6 between the drying cylinders 4.1 and 4.2 and the dry wire suction roll 5. The stabilizing devices 7.2 and 8.2 loaded with negative pressure are connected via channels to the negative pressure chambers 7.5 and 8.5 of the removal devices 7.1 and 8.1 to generate and maintain negative pressure in the stabilizing devices 7.2 and 8.2, which have throttling elements 7.8 and 8.8 designed as throttling valves 7.8 and 8.8. Since the negative pressure in the stabilizing devices 7.2 and 8.2 is always lower than the negative pressure in the negative pressure chambers 7.5 and 8.5 of the removing devices 7.1 and 8.1, the negative pressure in the stabilizing devices 7.2 and 8.2 can be adjusted by the throttle valve.

[0044] To laterally seal the negative pressure chambers 7.5 and 8.5 of the removal and stabilizing devices 7.1 and 8.1, air knives (not shown here) can be provided on both sides, i.e., at the edges of the guide side and the drive side of the first and second web stabilizers 7 and 8, respectively. These air knives are connected to overpressurized air chambers used to generate air jets deflected by the Coanda effect. Air knives for sealing the space relative to a moving wall, in the current case, a moving dry-net seal, are known and constitute an air curtain. Mechanical seals can also be used instead of air knives.

[0045] Pressure sensors 7.3, 7.4, 8.3, and 8.4 are disposed in the negative pressure chambers 7.5 and 8.5 of the removal devices 7.1 and 8.1 and the stabilizing devices 7.2 and 8.2. These pressure sensors are connected to the computing unit 10 via measurement data lines 11.1, 11.2, 11.3, and 11.4. The measurement data lines transmit the current operating parameters of the material width stabilizers 7 and 8, measured by the sensors, to the computing unit 10. Within the scope of this invention, it is also feasible to connect other sensors to the computing unit 10 via other measurement data lines. These other sensors may be pressure sensors in the dry web suction rollers, pressure sensors in overpressured air chambers for correspondingly generating air jets, or wear sensors for measuring the wear of the machine-width seals 7.6, 7.7, 8.6, and 8.7 of the removal devices 7.1 and 8.1.

[0046] The calculation unit 10 is also connected to the process control system of the paper machine via process data line 9.1. Process data may include, for example, the area weight of the produced fiber web, machine speed, wire tension, steam pressure in drying cylinders 4.1, 4.2, and 4.3, and the dry content of the fiber web 3 in the corresponding web stabilizers 7 and 8. Taking into account the process data from the process control system 9, the calculation unit 10 analyzes the operating parameters transmitted via measurement data lines 11.1, 11.2, 11.3, and 11.4 to determine the control signals affecting the operating parameters. These control signals are transmitted via control signal lines 10.1, 10.2, and 10.3 to the corresponding actuators 7.8, 8.8, 12.1, 13, and 14. In this example, these actuators are throttle valves 7.8 and 8.8, drive motor 12.1, and throttle valves 13 and 14.

[0047] Although only a portion of the drying section with two material width stabilizers 7 and 8 is shown in the example, the invention can also be adapted to individual drying units or even the entire drying section.

[0048] List of reference numerals

[0049] 1 device

[0050] 2. Drying process

[0051] 3 Fiber width

[0052] 4.1 Drying cylinder

[0053] 4.2 Drying Cylinder

[0054] 4.3 Drying Cylinder

[0055] 5 Dry Net Suction Rollers

[0056] 6 Dry Net

[0057] 7 First material width stabilizer

[0058] 7.1 Removal of the device

[0059] 7.2 Stabilizing Device

[0060] 7.3 Pressure Sensor

[0061] 7.4 Pressure Sensor

[0062] 7.5 negative pressure chamber

[0063] 7.6 Sealing device

[0064] 7.7 Sealing device

[0065] 7.8 Throttling element

[0066] 8 Second material width stabilizer

[0067] 8.1 Removal of the device

[0068] 8.2 Stabilizing Device

[0069] 8.3 Pressure Sensor

[0070] 8.4 Pressure Sensor

[0071] 8.5 negative pressure chamber

[0072] 8.6 Sealing device

[0073] 8.7 Sealing device

[0074] 8.8 Throttling element

[0075] 9 Process Control Systems

[0076] 9.1 Process Data Line

[0077] 10 computing units

[0078] 10.1 Control signal lines

[0079] 10.2 Control signal lines

[0080] 10.3 Control signal lines

[0081] 11.1 Measurement data cable

[0082] 11.2 Measurement data cable

[0083] 11.3 Measurement data cable

[0084] 11.4 Measurement data cable

[0085] 12-row fans

[0086] 12.1 Actuators and drive motors

[0087] 13 Actuators and throttle valves

[0088] 14. Actuators and throttle valves

[0089] 15. Direction of movement

[0090] 16 pipes

Claims

1. A method for improving the efficiency of the drying process in a paper machine by means of a process control system (9) during the manufacture of a fiber web (3), wherein, for drying, the fiber web, together with a permeable dry wire (6), is zigzag-intermittently guided through a plurality of steam-heated drying cylinders (4.1, 4.2, 4.3) and a plurality of dry wire suction rolls (5) in at least one drying unit, and web stabilizers (7, 8) are provided between these steam-heated drying cylinders (4.1, 4.2, 4.3), the web stabilizers having respectively a negative pressure removal device (7.1, 8.1) and a negative pressure stabilizing device (7.2, 8.2) for stabilizing the fiber web (3) removed from the respective drying cylinders (4.1, 4.2, 4.3) by the removal device and also for stabilizing the fiber web (3) through the stabilizing device (7.2, 8.2) until the subsequent operation of the negative pressure dry wire suction rolls (5), Its features are, a) Multiple web stabilizers (7, 8) are each equipped with at least two sensors (7.3, 7.4, 8.3, 8.4) for measuring operating parameters, and the subsequent dry web suction roller (5) is equipped with a sensor for measuring operating parameters, and b) A computing unit (10) is provided, and c) The computing unit (10) is connected to the process control system (9) of the papermaking machine, and d) In the calculation unit (10), the measured operating parameters of the web stabilizers (7, 8) and / or the dry web suction roller (5) are analyzed together with the process data of the process control system (9), and control signals (10.1, 10.2, 10.3) are output to multiple actuators (7.8, 8.8, 12.1, 13, 14) effectively connected to the web stabilizers (7, 8), wherein the process data is selected from a group consisting of the unit area weight of the fiber web, machine speed, dry web tension, steam pressure in the drying cylinders (4.1, 4.2, 4.3), and dry content of the fiber web (3) in the regions of each web stabilizer (7, 8), and e) Controlling multiple actuators (7.8, 8.8, 12.1, 13, 14) of multiple material width stabilizers (7, 8) via the control signals (10.1, 10.2, 10.3), The negative pressure in the removal device (7.1, 8.1) and / or the negative pressure in the stabilizing device (7.2, 8.2) and / or the negative pressure in each dry web suction roller (5) are pre-adjusted, i.e., reduced or increased, by multiple actuators (7.8, 8.8, 12.1, 13, 14).

2. The method according to claim 1, characterized in that, Multiple material width stabilizers (7, 8) are each equipped with multiple independent actuators.

3. The method according to claim 2, characterized in that, These independent actuators (7.8, 8.8, 12.1, 13, 14) are controlled by multiple independent control signals (10.1, 10.2, 10.3).

4. The method according to claim 1, characterized in that, Analyze the operating parameters of at least two sensors and / or signals from multiple actuators (7.8, 8.8, 12.1, 13, 14) to pre-determine the wear of at least one seal (7.6, 7.7, 8.6, 8.7) included in the removal device (7.1, 8.1).

5. The method according to claim 1, characterized in that, The negative pressure in the removal device (7.1, 8.1) and / or the negative pressure in the stabilizing device (7.2, 8.2) and / or the negative pressure in each dry web suction roller (5) is generated by at least one exhaust fan (12), which is directly or indirectly connected to the removal device (7.1, 8.1) and / or the stabilizing device (7.2, 8.2) and / or the subsequent dry web suction roller (5) via a pipe (16).

6. The method according to claim 5, characterized in that, At least one exhaust fan (12) is driven by a motor (12.1) with controllable speed, and / or the duct (16) is equipped with at least one controllable throttling element (7.8, 8.8, 13, 14).

7. The method according to claim 6, characterized in that, The motor (12.1) and / or the throttling element (7.8, 8.8, 13, 14) are used as actuators.

8. The method according to claim 1, characterized in that, The sensors (7.3, 7.4, 8.3, 8.4) of the material width stabilizers (7, 8) are selected from the group consisting of pressure sensors, displacement sensors, position sensors and wear sensors.

9. The method according to claim 1, characterized in that, The computing unit (10) is equipped with an autonomous learning algorithm for determining control signals (10.1, 10.2, 10.3) in order to optimize the efficiency of the drying process (2).

10. The method according to claim 1, characterized in that, It is equipped with two overpressure chambers on the sides for forming the air knife.

11. An apparatus for improving the efficiency of the drying process (2) in a paper machine by means of a process control system (9) during the manufacture of a fiber web (3), the apparatus being used to implement the method according to claim 1, wherein, for drying, the fiber web, together with a permeable dry wire (6), is zigzagly and alternately guided through a plurality of steam-heated drying cylinders (4.1, 4.2, 4.3) and a plurality of dry wire suction rolls (5) in at least one drying unit, and web stabilizers (7, 8) are provided between these steam-heated drying cylinders (4.1, 4.2, 4.3), the web stabilizers having respectively a negative pressure removal device (7.1) and a negative pressure stabilizing device (8.2), the stabilizing device being used to stabilize the fiber web (3) removed from the respective drying cylinders (4.1, 4.2, 4.3) by the removal device and also for stabilizing the fiber web (3) through the stabilizing device (7.2, 8.2) until the subsequent operation of the negative pressure dry wire suction rolls (5), Its features are, a) Multiple web stabilizers (7, 8) are each equipped with at least two sensors (7.3, 7.4, 8.3, 8.4) for measuring operating parameters, and the subsequent dry web suction roller (5) is equipped with a sensor for measuring operating parameters, and b) A computing unit (10) is provided, and c) The computing unit (10) is connected to the process control system (9) of the papermaking machine, and d) In the calculation unit (10), the measured operating parameters of the web stabilizers (7, 8) and / or the dry web suction roller (5) are analyzed together with the process data of the process control system (9), and control signals (10.1, 10.2, 10.3) are output to multiple actuators (7.8, 8.8, 12.1, 13, 14) effectively connected to the web stabilizers (7, 8), wherein the process data is selected from a group consisting of the unit area weight of the fiber web, machine speed, dry web tension, steam pressure in the drying cylinders (4.1, 4.2, 4.3), and dry content of the fiber web (3) in the regions of each web stabilizer (7, 8), and e) Controlling multiple actuators (7.8, 8.8, 12.1, 13, 14) of multiple material width stabilizers (7, 8) via the control signals (10.1, 10.2, 10.3), The negative pressure in the removal device (7.1, 8.1) and / or the negative pressure in the stabilizing device (7.2, 8.2) and / or the negative pressure in each dry web suction roller (5) are pre-adjusted, i.e., reduced or increased, by multiple actuators (7.8, 8.8, 12.1, 13, 14).

12. The device according to claim 11, characterized in that, It is equipped with two overpressure chambers on the sides for forming the air knife.

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