DE102007055689A1 - Paper machine and method for influencing the zonal water weight - Google Patents

Abstract

The invention relates to a method for adjusting, in particular control, the water weight of a pulp of a paper machine, in particular a dilution hydrogen casserole, wherein the pulp is guided as at least one fibrous web. The fibrous web comprises at least two zones in which the fibrous material for influencing, in particular for stabilizing and equalizing, its zonal water weight Addivitve zones are zugebbar. Due to the additives, the dewatering of the pulp can be influenced in zones, in particular zonewise steigerbar or reducible. Furthermore, the invention relates to a dewatering device, in particular as part of a paper machine having a fibrous web. The dewatering device has, in particular in a wet end, zonal distributed over the fibrous web, operating according to the inventive method, in particular networked control devices.

Description

The The present invention relates to a method for adjusting, in particular control, of the water weight of a pulp of a paper machine, in particular a dilution hydrogen casserole, wherein the pulp is guided as at least one fibrous web is. Furthermore, the present invention relates to a dewatering device, especially as part of a paper machine implementing the method.

to It has been producing paper since the end of the 18th century paper machines, in particular long-screen paper machines, use. As an example, the Fourdrinier paper machine may be mentioned which are a long-screen paper machine with steam-heated dryer section is. There are also other types of paper machines such as the rotary screen paper machine, the archery machine, the Paper machine with jet shapes, which is a screenless machine, or the paper machine with anhydrous foliar formers after electrostatic principle. The latter species only fall so far under the paper machine term used here, if these Machines of pulp, albeit only partially, as watery Fiber web is guided. Since middle / end of the 80's of the last century find paper machines with twin-wire formers in use of gap formers their use.

The quality of the paper produced with the help of a water-based paper machine, such as the basis weight (FG), which is also referred to as basis weight and after DIN ISO 536 depends on the processes in the wet end of the paper machine. At the beginning of the wet end of a paper machine, it is known that the pulp, that is to say the aqueous pulp or wood pulp suspension, is applied to a sieve by a device, the so-called headbox. In the case of this screen, for example in the case of the wire screening machine, it is usually a close-meshed wire screen in the form of an endlessly circulating belt. The sieve can also consist of a particularly coarse-meshed fabric, such as a plastic net.

To when applied to the sieve, the pulp loses gravity or for additional vacuum extraction with the help of drainage elements continuously water, that is the water weight of the Fibrous material on the wire increases in the machine direction (MD, Machine Direction). This will change the formation of the pulp to paper, that is, the sheet formation allows. Also in subsequent lots of the paper machine, such as the press and the dryer section, the water weight is further reduced.

When leaving the dryer section one speaks of "oven-dry" paper, short otro, formerly also atro for "absolutely dry" called. This term is in DIN 6730 "Paper and cardboard terms" or for pulp in DIN EN 20638 "Pulp, content, dry content" standardized.

Because of the ongoing water weight reduction in the machine direction, short MD direction, a paper machine can be used essentially as a dewatering device be considered for the pulp. As machine direction is usually referred to that direction in which the Pulp during the papermaking process of the paper machine is moved.

At the Headbox becomes the consistency, which is essentially the water weight, of the pulp in the cross-machine direction (CD, Cross Direction), that is, in the direction normal to the machine direction, usually first by means of dilution water set. This setting is useful because it is for example because of locally different lip openings of the headbox or because of different drainage in the cross machine direction on the screen to FG / Otro deviations in the cross machine direction of Fiber web, that is to deviations of the basis weight in the cross-machine direction of the oven-dry paper, can come. Such deviations adversely affect the formation cross profile and are therefore undesirable. One with dilution water working headbox is used as dilution hydrogen casserole designated. Instead of the "cross profile" is in the jargon The paper manufacturer also likes to talk about "CD profile". It is known to influence the dilution hydrogen casserole of the Otro / BW CD profile, where "BW" for "Basis Weight" translates Basis weight (FG), stands.

In spite of the adjustment of the consistency, in particular the water weight, of the pulp by means of dilution water at the dilution hydrogen casserole It may be in the machine direction, but in particular also in the cross machine direction, for example because of uneven Drainage on the screen, to unsatisfactory formation profiles, in particular to unacceptable Formationsquerprofilen the paper come.

From the WO 99/64963 A1 is a Scherungs- and formation control or regulation for the pulp of a paper machine known. The main factors for influencing the formation and the strength of the paper produced are, in particular, (1) the ratio of the speed of the pulp as it exits the paper Dilution water headbox to the speed of the sieve, (2) the angle between the pulp jet of the dilution hydrogen headbox and the sieve surface and (3) the rate of dewatering of the pulp on the sieve.

The The document describes a water weight sensor which can be arranged under the sieve, with the three properties of a material, especially the pulp a paper machine that can be measured: the conductivity or the resistance, the dielectric constant and the distance of the material to the water-weight sensor, depending the material dominates one or more than one of these properties. The response time of such a water-weight sensor is approx. one millisecond, so sampling frequencies of about 600 measurements can be reached per second.

The Water weight sensors are placed in the paper machine along the Positioned MD direction, where to keep the distance constant between fiber and sensor the individual sensors touch the screen. A sensor arrangement is used to increase the water weight in Measure MD direction on the screen of a Fourdrinier paper machine and water weight or drainage profiles to customize.

By the detection of the water weight history of each water weight sensor The sensor arrangement in the MD direction, it is possible, the individual To correlate water weight courses. Out the determined temporal offset of the individual water weight gradients can the control system result in the speed ratio, that is the ratio of pulp jet velocity to record sieving speed and adjust to an optimal Formation, ie sheet formation and strength to realize.

With Help of the water weight sensor assembly can be made by hand and with the help of laboratory measurements for a certain type of paper optimally configured paper machine the optimal drainage profile locally and measured in time and recorded respectively get saved. The records of this optimal drainage profile are subsequently processed by curve fitting to be parameterized Curves (nominal profile), such as exponential functions, too which approximate and interpolate the data sets and at the same time a smoothing in terms of unwanted Cause noise in the record values.

In subsequent production runs of the paper machine the goal is to get the optimal drainage profile (target profile) to reproduce. If the measured moisture content, that is Water weight at a certain point of the fibrous web, either over or below the setpoint for that location, the Machine parameters, such as pulp jet velocity, pulp web speed, the screen speed or the drive load controller adapted or adjusted to the deviating value closer to the setpoint introduce.

The doctrine of WO 99/64963 A1 draws the attention of the skilled in the sensor assembly and the detection of the water weight profile in the MD direction, as well as for guiding the papermaking process close to the target profile on the control of conventional machine parameters such as the speed ratio of pulp jet and wire. A disadvantage in this context is that influencing, in particular control, of the transverse profile of the method described in this document or of the device of this document is not provided.

The EP 1 021 729 B1 describes a control of the wet end of a paper machine, in particular by means of the addition of paper chemicals. Paper chemicals are known to be used to impart certain properties to the paper or to improve certain paper properties or to achieve or support other necessary goals, such as improved control of the process. For process control, paper chemicals such as drainage aids, defoamers, retention aids, that is, agents that improve retention of fines and fillers on the fiber surface during dewatering, while accelerating dewatering through the papermaker's fabric and thus drying, pitch detergents (pitch dispersants). , Slimicides or corrosion inhibitors used. The production of quality paper requires the addition of appropriate amounts of these paper chemicals. The addition of paper chemicals and the subsequent reactions or interactions between the paper chemicals and the aqueous pulp suspension, as well as the chemical-physical processes in the wet end are referred to in the jargon as wet-end chemistry.

Particular attention is paid to the retention of non-fibrous additives, especially solids. In order to improve the retention, that is, the retention of these paper chemicals, it is useful to cause the corresponding paper chemicals, particularly the solids among the paper chemicals, to form bonds or aggregates which affect the cross-relationship caused by the dewatering on and in the fibrous web shear resist forces. This is achieved through the use of synthetic polymers. Correct wet-end chemistry, in particular control or regulation of wet-end chemistry, is required in order to produce a uniformly high-quality paper.

This is in the EP 1 021 729 B1 proposed to use the wet-end chemistry, in particular in addition to the above-described conventional control measures, in order to similar to the above under the WO 99/64963 A1 Described obtained target profiles in the production runs of a paper machine to reproduce. If the determined by means of a sensor array of water weight sensors in the MD direction moisture content at a certain point of the fibrous web either above or below the determined for this point setpoint, the machine parameters, such as the mechanical procedure of the refiner, which is a pressure milling machine Corrugated grinding discs, or just the wet-end chemistry adapted to bring the process again closer to the target profile.

In one embodiment, in the EP 1 021 729 B1 a sensor arrangement of water weight sensors in the CD direction described. Each water weight sensor of the sensor array is located below a portion of the screen which guides the pulp in a fibrous web and measures the water weight of the pulp passing above the sensor array. The sensor assembly provides a continuous measurement of the entire pulp along the CD direction at the point where the fibrous web passes the sensor assembly. A profile of a variety of water weight measurements at different positions in the CD direction is created.

In the EP 1 021 729 B1 will be in the appreciation of the state of the art US 3,713,966 in which a device for measuring the transverse profile, that is, the CD profile of the moisture content of a moving fibrous web, in particular paper, is described. This device determines individually and at least approximately simultaneously the moisture content in different areas across the fibrous web. The moisture contents of the individual regions across the fibrous web obtained by these measurements are stored and transferred to display means in order to control the moisture content of the material of the fibrous web.

One A certain disadvantage of the latter two is that that the expert can not infer from them, at which points or places the wet end chemistry in the above Meaning can be influenced or should, in short, the expert does not know where to add the paper chemicals to to guide the process close to the determined nominal profile.

In the doctoral thesis "Investigations on the effect of polymeric retention aids on the filler distribution in papers" from the Department of Chemistry of the Technical University of Darmstadt, submitted by Dipl.-Chem. Alexander Bernal Peña from Bogotá, Colombia, published Darmstadt 2006 , the effects of various polymeric additives, multi-component systems, dry strength agents and fixatives on the regulation of cluster formation and fixation are described, which by clusters does not mean simple aggregation of filler particles such as filler particle aggregates, for example by pre-flocculation, but the formation of secondary particles, consisting of Füllstoffprimärteilchen and polymers. One group of substances that can lead to the formation of such filler clusters are hydrocolloids, which include modified starch. Another group are cationic polymers which, depending on their affinity for fibers and fillers, preferentially bind the latter directly to the fibers of the pulp or form readily regenerable fines and filler clusters.

Of the WO 99/55959 A1 a device and a method for sheet measurement and control in paper machines can be seen. The document describes inter alia the measurement of CD profiles, in particular water weight profiles in the cross-machine direction of the paper machine with the aid of water-weight sensors. By arranging the water weight sensors in the cross machine direction, the CD water weight profile is obtained instantaneously, whereby the MD and CD changes are determined substantially decoupled. As intervention points for the control, the raw material supply rate at the beginning of the wet end, the steam quantity regulation in the dryer section or the variation of the roll contact pressure in the press section are mentioned in the prior art. It mentions the possibilities of intervention in numerous, independently controllable or controllable actuators, which extend in each control range across the width of the pulp. For example, the headbox, the steam generation with numerous steam actuators, which regulate the applied to the individual zones across the sheet amount of heat, called. Similarly, in the calender section, where segmented calender rolls include a plurality of roller pressure control actuators applied to the sheet between the rolls in individual zones in the cross-machine direction. The control can be done by an operator or by means of control systems, which under Evaluation of signals from scanners Automatically adjust actuators in cross machine direction. Factors for uneven cross machine direction dewatering which as a result are responsible for fluctuations in the CD profile of the paper include the uneven supply of the pulp to the headbox, the clogging of the plastic mesh of the wire, the different mechanical tension of the wire and the unbalanced vacuum suction. On the possibilities of regulating paper properties using paper chemicals is not discussed in this document.

The Paper industry has a need for processes that manufacture of paper with one possible in both MD and in CD direction uniform, that is a flat over the entire fibrous web defined, allow nominal profile corresponding formation profile or on paper machines that implement such methods.

at the method according to the invention for adjusting, In particular regulation, the water weight of a pulp one Paper machine, in particular a dilution hydrogen casserole is the pulp is guided as at least one fibrous web, wherein the fibrous web at least two zones in the cross-machine direction includes. In the zones are the pulp to influence, in particular for stabilization and equalization, his zonal water weight additives zonewise zugebbar. By the additives the dewatering of the pulp can be influenced zone by zone. The dewatering is by means of the additive addition in particular Increasable or reducible zone by zone. By the zonal addition Additives make it possible to even out the retention and to stabilize. This has a more stable and consistent Ash transverse profile, and in the result a more stable and uniform Formation result. Zonal formation disorders, such as Displacements can be reliable in this way be avoided.

The Additions of the additives take place according to the invention by means of zonal distributed over the fibrous web of the paper machine Adding devices. The adding device is preferably as At least zonal water weight a pipe. In particular, the adding device can preferably by be realized a plurality of transverse to the machine direction transverse tubes. Characterized in that the adding devices zonal over the fibrous web distributed, the paper chemicals can advantageously be introduced to places in the papermaking process, where they are needed, for example in places which increases the retention of fillers or should be reduced.

The Addition device is preferably with at least one nozzle fitted. The nozzle preferably influences endlings on the pipe, the flow and distribution of the additives the fibrous web of the paper machine in the respective zone. The In particular, the nozzle can concentrate on the additives Let the fibrous web flow. Furthermore, the nozzle can the additives preferably evenly over apply a zone spread over the fibrous web. By the defined application of the additives on the fibrous web through The nozzle succeeds advantageously, the retention in the respective zone according to the requirements of the overall process adjust or regulate.

Favorable The adjustment of the individual zonal additions takes place with Help from control circuits. By the control circuits are preferably the pressure and / or the flow of the addition devices adjustable. Preferably, the method performs the choice of setting the additive in terms of type and quantity autonomous and self-controlling by. This manages the setting of the required quantities on added additives such as retention agents in defined and meet the requirements of modern quality assurance Wise.

Especially it is advantageous if the setting of the individual zonal additions with the help of control circuits, by which the differential pressure is adjustable between the adding devices. So can a more or less in the addition of additives in those zones where This is required to be set reliably. Advantageously, by the differential pressure control networking the individual zone controller, which, as a result, favorably to an improvement of the formation cross profile of the produced Paper leads.

The Setting the zonal additions can according to the invention by a, preferably human, operator manually carried out be. This is especially true when determining target profiles advantageous for new types of paper.

Especially for ongoing production, it is advantageous if the Setting the zonal additions automatically, in particular by means of at least one feedback loop per zone, in particular with at least one microprocessor, is feasible. An automated control by microprocessor increases advantageously the productivity of the paper machine and the quality assurance of the paper industry is very important opposite.

As an actuator for the addition per zone is min least one valve, in particular a ball valve, usable. By a valve, in particular a ball valve, the addition streams, that is, the addition amounts per unit time of additives in the individual zones can be advantageously controlled reliably.

It is preferred if with at least one one-dimensional sensor arrangement of water weight sensors, the zonal water weight transverse to the machine direction is measured. The sensor arrangement is preferably behind or in at least one dewatering element of the wet end the paper machine arranged. By the arrangement of the water weight sensors transverse to the machine direction, that is in the CD direction, it is possible, advantageously, the deviations of the zonal water weight to determine the nominal profile and subsequently via the controller or regulation of the addition of paper chemicals such as retention aids the drainage respectively the drainage respectively the reluctance of, for example, fillers to accomplish.

Especially it is preferred when for zonal detection of drainage in the MD direction, at least one multi-dimensional sensor arrangement of water-weight sensors is present. That's what the water weight sensors do both in CD and MD direction, thus two-dimensional, are arranged distributed. By the multidimensional, in particular two-dimensional, sensor arrangement succeeds advantageously the areal registration of the water weight of the fibrous web.

Especially it is also preferred if the water weight for each zone separately on at least one arbitrarily selectable Place along the fibrous web of the paper machine in the MD direction is controllable. Due to the zonal regulation on a freely selectable Position along the fibrous web can advantageously the ash profile and consequently the formation profile is favorably influenced become.

Especially it is favorable if the drainage curve for Each individual zone can be specified and adjusted separately. Because the Zones both a sub-area in the CD direction and a sub-area in MD direction of the fibrous web can be defined by the definition drainage curves for each zone and the separate adjustment advantageously a particularly uniform and stable formation of the pulp to paper can be achieved.

advantageously, can be used as additive retention aids or fillers, in particular cationic, anionic or neutral polymers. By adding these additives, the drainage can be particularly be effectively and efficiently controlled or regulated.

The Addition of the additives can advantageously be in the HC strand, that is in the "High Consistency" strand, translated in the strand with high consistency, that is on the headbox of the sieve, or in the area of the headbox, the dewatering device or the sieve. However, it is also possible the Additives in the LC strand, ie in the "Low Consistency" strand, translated in the strand with low pulp consistency, that is on the white water side of the screen, to admit. Depending on the type of added Additive is the appropriate place to choose.

Especially it is preferred if a zonal profile of the water weight for the entire longitudinal extent of the fibrous web predetermined and is einregelbar. This allows retention for the entire Area of the fibrous web stable and even be adjusted, resulting in the result over the entire Extension of the fibrous web a particularly stable and uniform Forma tion stops. Advantageously, can on this Way formation disturbances in the entire area of the fibrous web regulated or their occurrence, especially in the on the wet end following games, such as the dry or the Press section, be avoided.

The invention further relates to a dewatering device, in particular as part of a paper machine having a fibrous web, wherein the dewatering device, in particular in a wet end, zonal distributed over the fibrous web, according to the method described above, in particular networked, control devices. In this case, the addition devices, in particular their outlet openings or nozzles, represent the output or connection size of the individual zones. The tubes, in particular their section in the direction of the fibrous web towards the valve, are to be modeled by the person skilled in the art as delay lines. If, as is preferred, the valves, which as actuators are capable of gradually releasing the additive addition, are located close to the respective outlet opening or the nozzle of a tube, then essentially only the delay time it takes for the additive particles to be applied to the Fall down fibrous web, in the control concept to consider. The specification of the zonal profile of the water weight is the multi-dimensional, in particular two-dimensional, field of the setpoint variables, according to which the individual zone controllers are to be designed by a person skilled in the art. The advantage of such a device lies precisely in the fact that by the described embodiments of the invention Device, in particular the zonal control circuits, the retention over the known from the prior art ago can be uniformed and stabilized. This improved retention results in a more stable and uniform ash transverse profile, and as a result, a more stable and uniform formation. Zonal formation disturbances, such as, for example, depressions, can be reliably avoided in this way with the dewatering machine or paper machine according to the invention.

Further advantageous properties and embodiments of the invention are by way of example with reference to the drawings explained below described. In these drawings shows

1 a side view of the wet end of an embodiment of a paper machine according to the invention with arranged below the wire drainage elements and water weight sensors;

2 a plan view of the fibrous web with dashed indication of the zones;

3 a side view of the HC-strand with symbolic representation of the addition of additives, both directly into the HC strand (dashed line) and indirectly via the (recycled) white water;

4 a plan view of the fibrous web including drainage elements, sensor assemblies, control loops and adding devices;

5 a course of the drainage curve for a zone; and

6 a zonal profile of the water weight for the entire longitudinal extent of the fibrous web.

In the following, an embodiment of a paper machine according to the invention 1 which describes the method according to the invention implemented.

The paper machine 1 has a wet end 109 with a dewatering device 110 on, in which a pulp 5 by means of a headbox 9 , in particular a dilution hydrogen casserole on a sieve 169 , For example, a wire, is applied. The headbox 9 points along the machine transverse direction 66 ( 2 ) of the fibrous web 13 at least one zonal unterilte fibrous outlet opening 10 on.

With the help of drainage elements 69 a first dewatering step takes place in a fibrous web 13 guided pulp 5 on the sieve 169 , The paper machine 1 includes even more games, such as a dryer section and a press section, as well as a spool, which, however, for the sake of clarity not in 1 are shown.

In the machine direction 65 are behind at least one drainage element 69 Water weight sensors 54 for measuring the water weight of the pulp 5 arranged. The machine direction 65 is in 1 indicated by an arrow. The water weight sensors 54 could also be in the drainage elements 69 be arranged, for example, be integrally formed with these.

The sieve 169 becomes headbox side by means of a breast roll 165 deflected and driven. The fibrous web 13 lies on top of the sieve 169 on and is running from this in the machine direction 65 and thus from the headbox 9 moved away, the pulp 5 running over the drainage elements 69 is drained. The drainage can be done by gravity or additionally by vacuum extraction.

The fibrous web 13 here includes two zones 17 . 21 ( 2 ). The zones 17 . 21 each extend over half of the entire transverse extent B of the fibrous web 13 , The fibrous web 13 could also have more than two zones 17 . 21 For example, it could include as many zones as zonal dilution water addition sites on the headbox 9 available. The zones 17 . 21 extend both in the machine direction 65 as well as in the cross machine direction 66 , The zones 17 . 21 extend here over the entire longitudinal extent L of the fibrous web 13 , However, they could also be shorter. For example, each of the zones could 17 . 21 in the machine direction 65 be divided at least once, which would result in at least four zones. There could also be more, in particular significantly more than four zones.

In the zones 17 . 21 are the pulp 5 for influencing, in particular for stabilizing and equalizing, its zonal water weight additives 25 zone-assignable. By the additives 25 is the drainage of the pulp 5 can be influenced zone by zone. In particular, the drainage of the pulp 5 through the additives 25 Increasable or reducible zone by zone. The addition of the additives can, for example, in the HC strand 93 respectively. The addition of the additives 25 However, it can also indirectly via the white water from the LC strand 97 respectively. This is schematically in 3 shown. Other possible addition locations are in the area of the headbox 9 , the dewatering device 110 or the sieve 169 ,

Additions of additives 25 take place by zonal over the fibrous web 13 the paper machine 1 distributed dispensers 29 ( 4 ). Such an adding device 29 is here as a zorbing instrument for the zonal water weight here a pipe 33 , It's like in 4 exemplified, two adding devices 29 present, which together several, namely two pipes 33 exhibit.

Each adding device 29 is with a nozzle 37 equipped, the endlings on the pipe 33 the flow and distribution of the additives 25 on the fibrous web 13 the paper machine 1 in the respective zone 17 . 21 affected. The additives 25 are directly or mixed with white water from the LC strand 97 of conveyors, such as pumps, into the pipes 33 pumped. These conveyors or pumps are not shown in FIG. 0 for the sake of clarity.

The setting of the individual zonal additions takes place with the aid of first control loops 41 through which the pressure or the flow of the adding devices 29 is adjustable. That in the paper machine 1 implemented method leads the choice of adjustment of additives 25 autonomous and self-controlling in terms of type and quantity.

The setting of the individual zonal additions takes place here additionally with the help of second control loops 45 through which the differential pressure between the adding devices 29 is adjustable. The control circuits 41 . 45 are thus networked.

The setting of the zonal additions is automatically carried out here. It could also be done manually by an operator. By means of several feedback loops 49 per zone 17 . 21 Be the ones from the water weight sensors 54 measured water weight values to a microprocessor 53 transfer. The feedback loops 49 For example, they may be implemented in their transmission parts by a bus. The microprocessor 53 compares the measured water weight values from the running process with stored zonal drainage curves 81 or with a stored zonal profile 101 and, on the basis of any deviations occurring, the actual control instructions corresponding to the desired values, with which the adding devices 29 over the first and second control circuits 41 . 45 be charged.

The microprocessor 53 is part of the controller of the control circuits 41 . 45 , The running in the machine direction 65 moving fibrous web 13 with the pulp 5 , whose water weight changes continuously in the machine direction, but also in the cross machine direction and can deviate from the predefinable setpoints, represents the controlled system.

As an actuator for the addition of additives 25 each zone becomes a valve 57 used. Here, each feed device 29 a ball valve 57 on. The ball valve valves 57 effect actuated by the control signals of the first and second control circuits 41 . 45 the addition of the additives 25 by gradually releasing or blocking the additive addition ( 4 ).

The behind a drainage element 69 arranged water weight sensors 54 form a one-dimensional sensor arrangement 61 , The sensor arrangement 61 measures the zonal water weight across the machine direction 65 , that is in the cross machine direction 66 ,

The one-dimensional sensor arrangement 61 form in their entirety for the zonal detection of drainage in the machine direction 65 a multi-dimensional, here a two-dimensional, sensor arrangement 73 of water weight sensors 54 ,

The water weight for each zone 17 . 21 is separately on a freely selectable place 77 along the fibrous web 13 the paper machine 1 adjustable in machine direction.

The drainage curve 81 is for each individual zone 17 . 21 specifiable and separately adjustable ( 5 ).

The additives 25 are retention aids or fillers, in particular cationic, anionic or neutral polymers. It could also be other paper chemicals, such as starch, but which may then have other purposes and other effects. The addition of the additives 25 takes place here in the HC-strand 93 , It could also be in the LC strand 97 respectively.

A zonal profile 101 the water weight is for the entire longitudinal extent of the fibrous web 13 specifiable and einregelbar. The flat zonal profile 101 points for each zone 17 . 21 a nominal profile of the water weight. Here is the nominal profile of all zones 17 . 21 identical. However, the nominal profiles could, especially in more than one zone in the machine direction 65 , especially in the machine direction 65 also differ from each other ( 6 ).

The described wet end 109 includes a dewatering device 110 , the part of the paper machine 1 is that the fibrous web 13 having. The dewatering device 110 the wet end 109 has zonal over the fibrous web 13 distributed, according to the inventive method working, networked, control devices 41 . 45 . 53 having.

Other embodiments of the method according to the invention or the dewatering device according to the invention are conceivable and possible. For example, the nozzles could 37 depending on the requirement of the process, different jet geometries of the added additives 25 , as a cone-shaped beam geometry realize. The process could also be used outside the paper industry. It could, for example, be used in industrial textile cleaning and care. Of course, the additives 25 then not paper chemicals, but specific fabrics for textile conditioning, such as starch for ironing large, after cleaning still wet fabric webs, wherein the addition of ironing strength according to a defined transverse or longitudinal profile (target profile) takes place. The sensors could also measure other variables than the water weight. The addition of the additives was then carried out in accordance with these feedback measured variables. The addition of the additives 25 could also be done for example with a kind of watering can or sieve, each opening of the Gießkannensiebs is assigned to a zone of the fibrous web. In this way, particularly small zones could be regulated separately, if necessary, depending on each other.

1

paper machine

5

fiber

9

headbox

10

Fiber exit port

13

Fibrous web

17

Zone

21

Zone

25

additive

29

adding device

33

pipe

37

jet

41

loop

45

loop

49

Feedback loop

53

microprocessor

54

Water weight sensor

57

Valve, Ball valve

61

sensor arrangement

65

Machine direction

66

CMD

69

dewatering element

73

sensor arrangement

77

Job

81

zonal drainage curve

93

HC loops

97

LC-strand

101

zonal profile

109

wet end

110

dehydrator

165

breast roll

169

scree

B

transverse extension

L

longitudinal extension

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 99/64963 A1 [0009, 0015, 0018]
• - EP 1021729 B1 [0016, 0018, 0019, 0020]
• US 3713966 [0020]
• WO 99/55959 A1 [0023]

Cited non-patent literature

• - DIN ISO 536 [0003]
• - DIN 6730 [0005]
• - DIN EN 20638 [0005]
• - "Investigations on the effect of polymeric retention aids on the distribution of fillers in papers" from the Department of Chemistry of the Technische Universität Darmstadt, submitted by Dipl.-Chem Alexander Bernal Peña from Bogotá, Colombia, published Darmstadt 2006 [0022]

Claims (16)

Method for adjusting, in particular regulating, the water weight of a pulp ( 5 ) of a paper machine ( 1 ), in particular a dilution hydrogen casserole ( 13 ), whereby the pulp ( 5 ) as at least one fibrous web ( 13 ), characterized in that the fibrous web ( 13 ) at least two zones ( 17 . 21 ) in the cross-machine direction ( 66 ) in which the pulp ( 5 ) for influencing, in particular for stabilizing and equalizing, its zonal water weight additives ( 25 ) are assignable zonewise, whereby by the additives ( 25 ) the dehydration of the pulp ( 5 ) can be influenced zone by zone, in particular zonewise steigerbar or reducible. Process according to claim 1, characterized in that the additions of the additives ( 25 ) by zonal over the fibrous web ( 13 ) of the paper machine ( 1 ) distributed adding devices ( 29 ), preferably the adding device ( 29 ) as a zonal water-weighting instrument at least one tube ( 33 ). Method according to claim 1 or 2, characterized in that the adding device ( 29 ) with at least one nozzle ( 37 ), preferably endings on the pipe ( 33 ) the flow and distribution of the additives ( 25 ) on the fibrous web ( 13 ) of the paper machine ( 1 ) in the respective zone ( 17 . 21 ). Method according to one of claims 1 to 3, characterized in that the adjustment of the individual zonal additions by means of first control circuits ( 41 ), by which the pressure of the adding devices ( 29 ), wherein preferably the method of selecting the setting of the additives ( 25 ) is autonomous and self-controlling in terms of type and quantity. Method according to one of claims 1 to 4, characterized in that the adjustment of the individual zonal additions by means of second control circuits ( 45 ), by which the differential pressure between the adding devices ( 29 ) is adjustable. Method according to one of claims 1 to 5, characterized in that the adjustment of the zonal additions manually by an operator. Method according to one of claims 1 to 6, characterized in that the adjustment of the zonal additions automatically, in particular by means of at least one feedback loop ( 49 ) per zone ( 17 . 21 ), preferably with microprocessor ( 53 ), is feasible. Method according to one of claims 1 to 7, characterized in that as an actuator for the addition per zone at least one valve ( 57 ), in particular a ball valve, can be used. Method according to one of claims 1 to 8, characterized in that with at least one one-dimensional sensor arrangement ( 61 ) of water weight sensors ( 54 ) the zonal water weight transverse to the machine direction ( 65 ), the sensor arrangement ( 61 ) behind or in at least one drainage element ( 69 ) is arranged. Method according to one of claims 1 to 9, characterized in that for the zonal detection of dewatering in the machine direction ( 65 ) at least one multi-dimensional sensor arrangement ( 73 ) of water weight sensors ( 54 ) is available. Method according to one of claims 1 to 10, characterized in that the water weight for each zone ( 17 . 21 ) separately on at least one arbitrary digit ( 77 ) along the fibrous web ( 13 ) of the paper machine ( 1 ) in the machine direction ( 65 ) is controllable. Method according to one of claims 1 to 11, characterized in that the drainage curve ( 81 ) for each individual zone ( 17 . 21 ) can be specified and separately einregelbar. Method according to one of claims 1 to 12, characterized in that the additives ( 25 ) Retention aids or fillers, in particular cationic, anionic or neutral polymers. Method according to one of claims 1 to 13, characterized in that the addition of the additives ( 25 ) in at least one, preferably both, of the strands ( 93 . 97 ), the HC strand ( 93 ) and the LC strand ( 97 ), or in the area of the headbox ( 9 ), the dewatering device ( 110 ) or the sieve ( 169 ) he follows. Method according to one of claims 1 to 14, characterized in that a zonal profile ( 101 ) of the water weight for the entire longitudinal extent of the fibrous web ( 13 ) can be specified and is einregelbar. Drainage device ( 110 ), in particular as part of a paper machine ( 1 ), which is a fibrous web ( 13 ), characterized in that the dewatering device ( 110 ), especially in a wet end ( 109 ), zonal over the fibrous web ( 13 ), according to the method of any one of claims 1 to 15 working, in particular crosslinked, control devices ( 41 . 45 . 53 ) having.