EP1069236A2 - Regulating the pressure in a headbox - Google Patents

Abstract

To control the pressure at the pulp suspension (100) delivery jet (5) of a stock inlet (1), at a papermaking or cardboard prodn. machine, at least one sensor (10) measures the pressure in the hydraulic zone linked to the delivery jet (5). The sensor (10) is within a channel (8) where the pulp suspension (100) is forced through by a pump (9). The pressure level, registered by the sensor (10), is used by a control unit to set the rotary speed of the pump (9). The pulp delivery jet (5) has at least one measurement point formed by at least one sensor (10) within the jet (5) and/or in the feed channel (8) and/or in the recirculation take-off channel (6). At least one measurement point with at least one sensor (10) is at least at one distributor. At least one pulp distributor (2) and/or at least one feed channel (8) has at least one additional take-off with at least one throttle set by a sensor. The opening and closing actions of the throttle control the timed pressure development at the pulp delivery jet (5). A time filter allows disturbances with a time constant of ≥ 0.5 sec. and pref. 1 sec. to be used for fine control. At least one distributor (2) is a lateral pulp distributor (3) and a central distributor. The stock inlet delivers the pulp suspension in a single layer or in multiple layers. An Independent claim is included for a pulp suspension pressure control operation, at a stock inlet, where the pressure is measured at or in the pulp suspension delivery jet (5) to control the rotary speed of the pump (9) in the feed channel (8) which carries the pulp suspension (100). Preferred Features: The hydraulic pressure is measured at the pulp delivery jet (5) and/or the feed channel (8) and/or a recirculation channel (6) and/or a pulp distributor (2). The conditions in the additional take-off channel are set by a valve. The lateral distributor (3) delivers the pulp suspension and/or extracted water from the fourdriniers.

Description

The invention relates to a control device for control, preferably for fine control, of pressure in a headbox with a headbox nozzle a paper or board machine hydraulically connected space, with at least a feed line for a fiber suspension, at least one distribution device for the fiber suspension and at least one derivative for the Excess fiber suspension from the distribution device (recirculation line). Furthermore, the invention relates to a control device according to the invention feasible procedure.

An essential quality factor of a paper or board web is that Uniformity of the properties, such as the weight per unit area or the formation, the manufactured track. In the manufacturing process of such a web there are numerous disruptive factors that affect the uniformity of the properties both across the machine width (CD) and in the longitudinal direction (MD) influence. A major disruptive factor that is mainly in the longitudinal direction affects, is the temporal variation in the amount of ejected through the headbox Fibrous suspension, which in turn directly with the course of time the pressure in the headbox nozzle and the pulp suspension feed system related. The pressure is made up of a dynamic and a static portion, which form the total pressure in the headbox nozzle. Pressure fluctuations lead to fluctuations in the output per unit of time Amount of fiber suspension through the outlet gap of the headbox nozzle and thus to changes in basis weight and fluctuations in the basis weight longitudinal profile of the paper or cardboard produced. For this Basically, the fiber suspension supplied is used in modern paper or board machines Regulated for the headbox as precisely as possible.

From the two German patent applications DE 197 36 047 A1 (PA10611 DE) and DE 197 36 048 A1 (PA10605 DE) of the applicant is both a control device also known as a control method in which the basis weight longitudinal profile the paper or cardboard web by measuring the basis weight the paper or cardboard web and subsequent speed regulation a feed pump is regulated in the feed line to the headbox.

The disadvantage of such a regulation is that the regulation on the one hand is relatively sluggish and on the other hand due to the inertia of the impeller Feed pump only relatively rough corrections are possible. Roughly means in this Context that the pressure fluctuations Δp down to a range of 4% to 3%, at best 2%. Here it should be noted that pressure fluctuations can be regulated the better the greater their time constant t, that is to say the time interval between two successive disturbances. The shorter the disturbances, the more they are worse and less precise to compensate.

It is therefore an object of the invention to provide a control device and a method for Improvement of the basis weight profile by regulating the pressure in one with the headbox nozzle of a headbox of a paper or board machine hydraulically connected room or duct to indicate which / which it allows a very fine (temporal and absolute) and quick correction the throughput of fiber suspension through a headbox.

The task is characterized by the features of the device claim 1 and Features of the method claim 14 solved.

The inventors have recognized that it is possible to adjust the time fluctuations of the Throughput of fiber suspension through a headbox very sensitive to influence that a control loop between the measured pressure in a room connected to the headbox nozzle, for example in the headbox itself, in particular in the headbox nozzle, or in a feed line of the fiber suspension in the headbox or in front of a throttle device further derivation from the distribution device. With this considered pressure, more precisely the pressure fluctuations, both the Total pressure, consisting of the dynamic and static pressure, or the static pressure alone or the static pressure together with one after Bernoulli calculated dynamic pressure can be used. The temporal Pressure fluctuations are in the total pressure as well as in the dynamic and recognizable in the static pressure component, measurable and usable for regulation. On the preferred location for pressure measurement is naturally the headbox nozzle itself, however, measurements can be taken in the overall fiber suspension supply of the headbox or other hydraulically coupled to the headbox nozzle Rooms can be used. The space in which the pressure is kept constant is preferably the headbox nozzle itself. However, due to the hydraulic connection also has another space in the area of the headbox, such as the distribution device or the feed of the fiber suspension after a conveyor unit or further derivation from the distribution device be used in front of a throttle device.

Accordingly, the inventors propose a control device for control, preferably for fine control, the pressure in one with a headbox nozzle a headbox of a paper or board machine hydraulically connected Space, with at least one supply line for a fiber suspension, at least a distribution device for the fiber suspension and at least one discharge line for the excess fiber suspension from the distribution device (Recirculation line) to further develop that at least one sensor to measure the pressure in the hydraulically connected to the headbox nozzle Space is provided and at least one in the supply line a speed-controlled and acted upon by the at least one sensor Pump (headbox pump) is located by changing its speed controls the pressure over time in the headbox nozzle. This gives the advantage that by means of an inexpensive unit in the form of a speed-controlled Pump the flow rate in the supply line to the headbox nozzle and thus the pressure prevailing in the headbox nozzle and its time Course can be regulated with constant cross sections.

The headbox nozzle is particularly suitable as a measuring point for the pressure measurement sensor. however also the supply line, the discharge line (recirculation line) or the Distribution device.

A particularly advantageous embodiment of the invention results when in the at least one distribution device and / or at least one feed line at least one further derivative with at least one of the at least one a sensor acted throttle device is located by opening and Closing regulates the time course of the pressure in the headbox nozzle. This further derivation with adjustable throttle device in the form of a subordinate Control loop has the advantage that it can be attached to the inlet into the Distribution device the excess fiber suspension very quickly and effectively dissipates from the distribution device, and this with low investment and operating costs.

In a further embodiment of the invention, at least one further sensor is used Measurement of the pressure provided in the at least one distribution device, wherein in the at least one distribution device and / or at least one Supply at least one further derivation with at least one of the at least another sensor acted throttle device is located by opening and closing the pressure over time in the headbox nozzle regulates. By means of this further sensor in the distribution device, the desired control engineering advantage of the shortest possible dead time a subordinate control loop with its own sensor as low as possible reached.

According to a particularly advantageous embodiment of the invention The inventors propose a control device that a time filter is provided in the control circuit which is exclusively disturbances with a time constant t of greater equal to half a second, preferably greater than or equal to one second, for Fine control allows. The time interval between two is used as the time constant t consecutive disorders viewed both periodically and stochastically can be done.

The selection of a very sensitive throttle device, for example, is advantageous a special throttle valve known per se, in particular a control valve, which is very sensitive to the flow rate in a certain range regulates, but does not allow complete curtailment. In this context is for example to the patent applications DE 43 05 688 A1 (PA04956 DE) and DE 44 02 515 A1 (PA10048 DE) of the applicant.

In further preferred embodiments of the invention, the known one Distribution device to be a cross or central distributor. Furthermore, the invention Control device a well-known single or multi-layer headbox be assigned.

This fine control according to the invention ensures that - due to the tests now carried out - instead of the currently usual, no longer settable Pressure fluctuations in the range of 3% to 4%, at best 2%, now maximum pressure fluctuations in the range of ± 1%, often ± 0.5%, and partially even only ± 0.3% can be realized.

bei 1,0s ≥ t > 0,5s ist Δp ≥ 1,5%,

bei 2,0s ≥ t > 1,0s ist Δp ≥ 1,0%,

bei 4,0s ≥ t > 2,0s ist Δp ≥ 0,5%,

bei t > 4,0s ist Δp ≥ 0,3%.

If one considers the interrelation of the time constant t of the disturbances and the maximum pressure fluctuations Δp still occurring from the mean total pressure p in connection with the fine control according to the invention, the following results were achieved in practice:

with 1.0s ≥ t> 0.5s, Δp ≥ 1.5%,

with 2.0s ≥ t> 1.0s, Δp ≥ 1.0%,

with 4.0s ≥ t> 2.0s, Δp ≥ 0.5%,

at t> 4.0s, Δp ≥ 0.3%.

According to the inventive concept, the inventors continue to propose a method to control, preferably fine control, the pressure in one with a Headbox nozzle of a headbox of a paper or board machine hydraulic connected space, with at least one feed line for a fiber suspension, at least one distribution device for the fiber suspension and at least one derivation for the excess fiber suspension from the Distribution device (recirculation line), which the following process steps comprises: measuring the pressure in at least one with the headbox nozzle hydraulically connected space, preferably in the headbox nozzle and Regulation of the speed of the at least one in the feed line for the fiber suspension attached pump (headbox pump) depending on the measured Print.

The pressure to be regulated lies, for example, in the supply line, the distribution device, the recirculation line or preferably in the headbox nozzle. As a measuring location the headbox nozzle is particularly suitable for the pressure measurement sensor, however also the supply line, the discharge line (recirculation line) or the distribution device.

A particularly advantageous method of the invention results if the temporal Course of the pressure in the headbox nozzle also by opening and closing at least one in at least one further, in the at least one distribution device and / or attached at least one feed line integrated lead Throttle device, which is acted upon by the at least one sensor is regulated. This procedure using another derivative with adjustable throttle device in the form of a subordinate control loop the advantage that they are very close to the inlet in the distributor the excess fiber suspension from the distribution device quickly and effectively dissipates.

Another method according to the invention provides that the time course the pressure in the headbox nozzle also by opening and closing at least one in at least one other, in the at least one distribution device and / or attached at least one feed line integrated lead Throttle device by at least one other, in the at least one Distributor attached sensor is acted upon, is regulated. Hereby the control engineering advantage results in the shortest possible dead time thanks to a subordinate control loop with its own sensor at low costs.

Another advantageous further development of the method provides that the Fine control only faults with a time constant t greater than or equal half a second, preferably one second.

In addition, it should be noted that the proposed regulation in both Use in connection with single-layer and multi-layer headboxes is. Furthermore, the distribution device used can be in the feed line for the fiber suspension be both a cross and a central distributor, as in the modern paper or board machines that work according to the dilution principle, for controlling the basis weight and fiber orientation cross profile is used. The distribution device can be used both for the fiber suspension and equipped for the white water with the control according to the invention become.

It should also be noted that the time filter specified above is in itself known way electronically or by appropriate computer programs can be realized.

It is understood that the foregoing and those yet to be explained Features of the invention not only in the respectively specified combination, but can also be used in other combinations or alone are without departing from the scope of the invention.

Additional features and advantages of the invention will appear from the following Description of preferred embodiments with reference to FIG the painting.

Figur 1:

Druckregelung am Stoffauflauf mit einer drehzahlgeregelten Pumpe in der Zuleitung;

Figur 1a:

Druckregelung am Stoffauflauf mit einer drehzahlgeregelten Pumpe in der Zuleitung und mit einer weiteren Ableitung in der Verteilvorrichtung;

Figur 1b:

Druckregelung am Stoffauflauf mit einer drehzahlgeregelten Pumpe in der Zuleitung und mit einer weiteren Ableitung in der Verteilvorrichtung mit getrenntem Sensor;

Figur 2:

Druckregelung am verdünnungswassergeregelten Stoffauflauf in der Verteilvorrichtung für die Faserstoffsuspension mit einer drehzahlgeregelten Pumpe in der Zuleitung für die Faserstoffsuspension, in der Verteilvorrichtung für das Siebwasser und mit einer weiteren Ableitungen in den beiden Verteilvorrichtungen mit getrennten Sensoren;

Figur 3:

Druckregelung am verdünnungswassergeregelten Stoffauflauf mit einem Zentralverteiler und mit einer weiteren Ableitung im Zentralverteiler.

The invention will be explained in more detail below with reference to the drawings. They represent:

Figure 1:

Pressure control at the headbox with a speed-controlled pump in the feed line;

Figure 1a:

Pressure control at the headbox with a speed-controlled pump in the supply line and with another discharge line in the distribution device;

Figure 1b:

Pressure control at the headbox with a speed-controlled pump in the supply line and with another discharge line in the distribution device with separate sensor;

Figure 2:

Pressure control on the dilution water-controlled headbox in the distribution device for the fiber suspension with a speed-controlled pump in the feed line for the fiber suspension, in the distribution device for the white water and with another discharge in the two distribution devices with separate sensors;

Figure 3:

Pressure control on the dilution water-controlled headbox with a central distributor and with a further discharge in the central distributor.

FIG. 1 shows a control device according to the invention using the example of a Headbox 1, consisting of a distribution device 2 in the form of a cross distributor 3, a turbulence generator 4 and a headbox nozzle 5 that machine-width the pulp suspension 100 on sieve, not shown, or distributed between two sieves, not shown. Further there is at least one derivative 6 at the end of the distribution device 2 (Recirculation line) through which the in the distribution device 2 possibly excess fiber suspension 100 removed becomes; the derivation 6 can also consist of several small derivation channels, the flow cross-sections and thus the flow rates individually, in Groups or in their entirety controlled or regulated, for example by a manually operated manual valve or, as shown in Figure 1, by a controlled Control valve, can be. The fiber suspension 100, which is shown as arrow 7 is shown, passes through a feed line 8, in which a speed-controlled pump 9th (Headbox pump) is arranged in the cross distributor 3 and becomes mostly via the turbulence generator 4 to the headbox nozzle 5, in the it creates a pressure. The pressure, especially a temporal change in the Pressure is measured by a sensor 10 and as a measured variable to the two control units 11 and 12 (PIC and SIC) connected in series are forwarded, which according to the laws of a control loop known per se make a possible correction to the speed of the speed-controlled pump 9 and thus the flow rate of fiber suspension and the prevailing Determine temporal pressures in the headbox with unchanged cross sections.

Should be achieved that both a wide range of the control range and at the same time a high level of sensitivity of the control around a given one Average is possible, so is the execution of one of the two following figures 1a and 1b particularly advantageous.

Figure 1a shows a control according to Figure 1, but is additional in addition to the speed-controlled pump 9 in the designed as a cross distributor 3 Distributor 2 attached a further derivative 13, the flow rate is regulated by means of a throttle device 14. The throttle device 14 receives their control variables directly from the two control units connected in series 11 and 12 (PIC and SIC), which, as already mentioned above, their measured variables again from the sensor 10 which is in the headbox nozzle 5 of the headbox 1 is attached, receives, In this embodiment, the rough control of the Pressure in the headbox nozzle 5 by the speed-controlled pump 9, while the fine control exclusively via the throttle device 14 is realized in the further derivation 13. As a rough regulation here Fluctuations in larger time intervals of e.g. Viewed 1.5 seconds, while the fine control of the fluctuations occurring in short intervals (<1.5 s) assumes. The attached in the derivative 6 of the distribution device 2 Control device for the flow of excess Fibrous suspension 100 is in this figure as a manually operated manual valve executed; the leads 6 can also be designed as described in FIG. 1 his. It should also be noted that the fiber suspension 100, which is shown as arrow 7 is represented by a feed line 8, in which a speed-controlled pump 9 (Headbox pump) is arranged, enters the cross-distributor 3.

Figure 1b shows a control according to Figure 1, but is additional in addition to the speed-controlled pump 9 in the designed as a cross distributor 3 Distributor 2 attached a further derivative 13, the flow rate is regulated by means of a throttle device 14. The throttle device 14 receives their controlled variables directly from one of the control unit 15 (PIC), which their measured variables from a sensor 16, which is attached in the distribution device 2 of the headbox 1 is received. In this embodiment, the rough regulation of Pressure in the headbox 5 by the speed-controlled already described above Pump 9 together with control circuit components (attached to the headbox nozzle 5 Sensor 10, control units 11 and 12) made during the Fine control exclusively via the throttle device 14 in the further derivation 13 is realized. As a general rule, fluctuations in larger intervals of e.g. Viewed 1.5 seconds while fine tuning the fluctuations occurring at short intervals (<1.5 s) are accepted. The derivative 6, as shown and described in FIG. 1, for example, be executed.

FIG. 2 shows a pressure control according to the invention on a dilution water-regulated headbox 1 with a distribution device 2.1 for the fibrous suspension 100 and a distribution device 2.2 for the white water 101 as a dilution strand. As already described in FIG. 1, fiber suspension 100, which is shown as arrow 7.1, is fed through the feed line 8.1 and the speed-controlled pump 9.1 (headbox pump) to the distribution device 2.1, whereas the white water 101, which is shown as arrow 7.2, is fed through the feed line 8.2 and the speed-controlled pump 9.2 of the distribution device 2.2 is supplied. Between the distribution device 2.1 and the turbulence generator 4, there are individual feed lines 17.1-17.4 for the fiber suspension and corresponding feed lines 18.1-18.4 for the white water strands (dilution water strands) coming from the distribution device 2.2, which are also regulated by means of a cross profile control, not shown here. The pressure, in particular a change in pressure over time, is, as already explained in FIG. 1, measured by a sensor 10 in the headbox nozzle 5 and passed on as a measured variable to the two control units 11, 12.1 (PIC and SIC) connected in series, which follow Make a possible correction to the speed of the speed-controlled pump 9.1 in accordance with the laws of a control circuit known per se and thus determine the delivery rate of fiber suspension 100 and the resulting temporal pressures in the headbox with unchanged cross sections. Correspondingly, the flow rate of white water 101 is measured in the feed line 8.2 by means of a flow meter 20 and passed on as a measured variable to the two control units 12.2 and 12.3 (FIC and SIC) connected in series, which, as already described for the fiber suspension 100, according to the laws of one make a possible correction to the speed of the speed-controlled pump 9.2 in a known control circuit and thus determine the delivery rate of white water 101.
In FIG. 2 it can also be seen that at least one further discharge line 13.1 and 13.2 are attached to the distribution devices 2.1 and 2.2 designed as cross distributors 3, the flow rates of which can be regulated by means of a respective throttle device 14.1 and 14.2. The throttle devices 14.1 and 14.2 receive their controlled variables directly from the respective control units 15.1 and 15.2 (PIC), which receive their measured variables from their associated sensors 16.1 and 16.2, which in turn are attached in their distributing devices 2.1 and 2.2 of the headbox 1. In this exemplary embodiment, the rough control of the pressure in the headbox nozzle 5 is carried out by the above-described speed-controlled pump 9.1 together with control circuit components (sensor 10, control units 11 and 12.1 attached to the headbox nozzle 5), while the fine controls are carried out exclusively via the throttle devices 14.1 and 14.2 in the further derivatives 13.1 and 13.2 are realized.

FIG. 3 shows a further, modern variant of a fiber suspension supply system for a headbox 1 with a central distributor 19 and the control according to the invention similar to Figure 1b. The difference is here however, the supplied pulp suspension 100, which is shown as arrow 7, through a feed line 8 to a central distributor 19 and from there via a large number of feeds 17.1 to 17.5, which are not shown here Cross section control are regulated, headed into the headbox 1. Moreover 17.1 to 17.5 are regulated white water supplies 18.1 to for each feed 18.5 shown, which are also connected to the cross profile control and in a manner known per se, the cross profile of the paper or Set the cardboard web. As already described in detail in FIG. 1b, the coarse control is speed-controlled in the supply line 8 Pump 9 together with control circuit components (attached to the headbox nozzle 5 Sensor 10, control units 11 and 12) made during the fine control based on that measured in the central distributor 19 by means of a sensor 16 Pressure exclusively on the attached in the further derivation 13 and throttle device 14 controlled by the control unit 15 is realized. In the derivation 6, a valve is attached that in a known manner as a manual valve (manual actuation) or as a control valve (actuation by means of a control circuit) can be executed.

Through these configurations of the regulation shown above, it is possible to two control loops relatively simple speed-controlled pumps and Use throttle valves and still achieve a high control quality.

In addition, by this invention, a control device and an overall Process for regulating the pressure in the headbox nozzle of a headbox a paper or board machine, which allow a very fine correction of the pressure in the headbox nozzle and thus the throughput to make fiber suspension through a headbox.

Reference list

1

Headbox

2, 2.1, 2.2

Distribution device

3rd

Cross distributor

4th

Turbulence generator

5

Headbox nozzle

6

Derivation (recirculation line)

7, 7.1, 100

Fibrous suspension

7.2, 101

White water

8, 8.1; 8.2

Supply

9, 9.1, 9.2

Speed controlled pump

10, 16, 16.1, 16.2

sensor

11, 15, 15.1, 15.2

Control unit (PIC)

12, 12.1, 12.3

Control unit (SIC)

12.2

Control unit (FIC)

13, 13.1, 13.2

Further derivation

14, 14.1, 14.2

Throttling device

17.1-17.5

Supply lines for the fiber suspensions

18.1-18.5

Supply lines for the white water strands

19th

Central distributor

20th

Flow meter

Claims (26)

Control device for controlling, preferably for fine control, the pressure in a space hydraulically connected to a headbox nozzle (5) of a headbox (1) of a paper or board machine, with at least one feed line (8) for a fiber suspension (100), at least one distribution device ( 2) for the fibrous suspension (100) and at least one derivative (6) for the excess fibrous suspension (100) from the distribution device (recirculation line) (2), characterized in that at least one sensor (10) for measuring the pressure in the Headbox nozzle (5) hydraulically connected space is provided and in the at least one feed line (8) there is at least one speed-controlled pump (headbox pump) (9) which is acted upon by the at least one sensor (10) and which changes the speed over time by changing its speed Regulates pressure in the headbox nozzle (5). Control device according to claim 1, characterized in that at least one measuring point of the at least one sensor (10) is located in the headbox nozzle (5) itself. Control device according to one of the preceding claims 1 to 2, characterized in that at least one measuring point of the at least one sensor (10) lies in the at least one feed line (8). Control device according to one of the preceding claims 1 to 3, characterized in that at least one measuring location of the at least one sensor (10) lies in the at least one discharge line (recirculation line) (6). Control device according to one of the preceding claims 1 to 4, characterized in that at least one measuring point of the at least one sensor (10) is located in the at least one distribution device (2). Control device according to one of the preceding claims 1 to 5, characterized in that in the at least one distribution device (2, 2.1, 2.2) and / or at least one feed line (8, 8.1, 8.2) at least one further derivative (13, 13.1, 13.2 ) with at least one throttle device (14, 14.1, 14.2) acted upon by the at least one sensor (16, 16.1, 16.2), which regulates the time profile of the pressure in the headbox nozzle (5) by opening and closing. Control device according to one of the preceding claims 1 to 5, characterized in that at least one further sensor (16, 16.1, 16.2) for measuring the pressure is provided in the at least one distribution device (2, 2.1, 2.2) and in the at least one distribution device (2, 2.1, 2.2) and / or at least one feed line (8, 8.1, 8.2) at least one further discharge line (13, 13.1, 13.2) with at least one throttle device (at least one further sensor (16, 16.1, 16.2)) 14, 14.1, 14.2), which regulates the time course of the pressure in the headbox nozzle (5) by opening and closing. Control device according to one of the preceding claims 1 to 7, characterized in that a time filter is provided which only permits interference with a time constant t of greater than or equal to half a second, preferably one second, for fine control. Control device according to one of the preceding claims 1 to 8, characterized in that a control valve is provided to influence the further discharge line (13). Control device according to one of the preceding claims 1 to 9, characterized in that the at least one distribution device (2) is a cross distributor (3). Control device according to one of the preceding claims 1 to 9, characterized in that the at least one distribution device (2) is a central distributor (19). Control device according to one of the preceding claims 1 to 11, characterized in that it is assigned to a single-layer headbox. Control device according to one of the preceding claims 1 to 11, characterized in that it is assigned to a multi-layer headbox. Method for controlling, preferably for fine control, the pressure in a space hydraulically connected to a headbox nozzle (5) of a headbox (1) of a paper or board machine, with at least one feed line (8) for a fiber suspension (100), at least one distribution device ( 2) for the fiber suspension (100) and at least one discharge line (6) for the excess fiber suspension (100) from the distribution device (recirculation line) (2), the method comprising at least the following process steps: 14.1. Measuring the pressure in at least one space hydraulically connected to the headbox nozzle (5), preferably in the headbox nozzle (5), 14.2. Regulation of the speed of the at least one pump (headbox pump) (9) mounted in the feed line (8) for the fiber suspension (100) as a function of the measured pressure. A method according to claim 14, characterized in that the pressure in the headbox nozzle (5) is measured. Method according to one of the preceding claims 14 to 15, characterized in that the pressure in the at least one feed line (8) is measured. Method according to one of the preceding claims 14 to 16, characterized in that the pressure in the at least one discharge line (recirculation line) (6) is measured. Method according to one of the preceding claims 14 to 17, characterized in that the pressure in the at least one distribution device (2) is measured. Method according to one of the preceding claims 14 to 18, characterized in that the time course of the pressure in the headbox nozzle (5) also by opening and closing at least one in at least one further, in the at least one distribution device (2, 2.1) and / or at least one feed line (8, 8.1) integrated discharge line (13, 13.1) attached throttle device (14, 14.1), which is acted upon by the at least one sensor (10). Method according to one of the preceding claims 14 to 18, characterized in that the time course of the pressure in the headbox nozzle (5) also by opening and closing at least one in at least one further, in the at least one distribution device (2, 2.1, 2.2) and / or at least one feed line (8, 8.1, 8.2) integrated discharge line (13, 13.1, 13.2) attached throttle device (14, 14.1, 14.2), which is used by at least one other, in the at least one distribution device (2, 2.1, 2.2 ) attached sensor (16, 16.1, 16.2) is regulated. Method according to one of the preceding claims 14 to 20, characterized in that the fine control only regulates faults with a time constant t greater than or equal to half a second, preferably one second. Method according to one of the preceding claims 14 to 21, characterized in that the further derivation (13) is influenced by a control valve. Method according to one of the preceding claims 14 to 22, characterized in that at least one transverse distributor (3) is used as the distribution device (2) for the fiber suspension feed and / or for a white water feed, if present. Method according to one of the preceding claims 14 to 22, characterized in that at least one central distributor (19) is used as the distribution device (2) for the fiber suspension feed and / or for an optionally available white water feed. Method according to one of the preceding claims 14 to 24, characterized in that it is applied to a single-layer headbox. Method according to one of the preceding claims 14 to 24, characterized in that it is applied to a multi-layer headbox.

Images