EP0824157A2 - Headbox and process for the distribution of a fibrous suspension in the headbox of a paper making machine - Google Patents

Abstract

In a process for distributing a suspension of fibrous material (stock) in the head box of a paper machine, different additive materials are injected into the stock at two or more different levels relative to the plane of the paper. Also claimed is a process in which different stock streams are supplied through two or more separate distributors, guiding devices, nozzles and slots in the head box. The stock supplied to form the outer (i.e. surface) layers of the paper contains: (i) fibres with a higher degree of milling; (ii) more filler or fines; or (iii) fibrous material which has been refined with a lesser amount of chemicals and has stronger fibres than the stock forming the inner layers. Further claimed is a head box in which the processes are carried out. Preferably the additives may be injected into the stock in the middle section (12), the nozzle (14), and/or the distributor (11) parts of the head box. The additives are fillers, chemicals (especially retention media), starch, suspensions of fibrous materials, or mixtures thereof. Less retention medium and/or less filler and/or fines are added to the centre of the stock flow than to the outer layers. The additives supplied to the centre of the web are those which increase strength, and those supplied to the outer layers increase printability. The concentration of the fibrous material in the stock may be adjusted in zones across the web width, whilst the volume flow rate of the suspension is kept substantially constant. Similarly, the additive streams may be adjusted in zones across the machine width and/or in the direction perpendicular to the web surface volume whilst flow rate is kept constant by the addition, as necessary, of water.

Description

The invention relates to a method for distributing a fiber suspension in the headbox of a paper machine, at which the fiber suspension from at least one distributor a guide device is guided into a nozzle from which it exits through a gap.

The invention further relates to a headbox for a paper machine with a distributor for distributing a fiber suspension across the machine width, via a guide device is connected to a nozzle from which the fiber suspension exits through a gap and with a metering device with dosing lines for the addition of additives.

A device and a method according to the above Art are known from DE 44 16 898 C2.

The headbox then comprises a guide device with a first turbulence insert in the form of a pipe distributor, the opens into a mixing chamber and a second turbulence insert in the form of a manifold that connects to the Nozzle passes over. A plurality of approximately opens into the mixing chamber Pipes arranged perpendicular to the main flow direction one from which an aggregate is stacked over different ones arranged outlet openings in the fiber suspension can be added.

In this way a local admixture of dilution water is said reached to the main flow of the pulp suspension in this way be admixed with simple means if possible evenly over the entire height of the suspension layer can be done so that a uniform influence on the Thickness of the sheet produced is possible.

In paper production there are often special paper properties desired on the web surface or in the boundary layers. For example, if good printability is desired, then For example, a high filler content is required on the surface. On the other hand, it is desirable to have the necessary Surface properties or edge properties only in the Realize surface layers or boundary layers in order to Keep the cost of the aggregates low.

With single-layer headboxes, it has so far not been possible to to vary the fabric properties in such a way that different Characteristics in the z direction can be generated.

To enable a variation of the properties in the z direction, multilayer headboxes were therefore often used, where the fibrous web e.g. from a middle class, from an upper layer and a lower layer is generated.

Such multi-layer headboxes have so far been predominant used for packaging and cardboard paper production. In this case e.g. into the middle layer of a three-layer Inferior waste paper and brought into the Outer layers of paper stock with higher strength or whiteness in Comparison to the middle class.

An application of multilayer headboxes to create Papers with increased filler content and improved printability so far only in the marginal layers theoretically considered (see T. Schaible, A. Bublik, "experiences and perspectives with multilayer sheet formation ", Das Papier, 1993, No. 10A, p. V140-V149), has however in practice not yet enforced due to various problems can.

The invention is therefore based on the object of a method for the distribution of a fiber suspension in the headbox To create paper machine and a headbox, with which a targeted influencing of the paper properties even with highly filled Papers on the sheet surface or in the marginal zones is made possible in the simplest possible way, and with what additional or alternatively a targeted influencing of the printability properties with graphic papers.

A suitable headbox is also to be created, with the benefits of optimizing paper properties in z-direction especially for graphic papers with one or multi-layer design can be used. It should also the pressure losses in the relevant metering lines kept as low as possible and as uniform as possible Distribution of the aggregates are made possible.

The object of the invention is in a method according to the initially mentioned type solved in that the fiber suspension on at least two different levels in the z direction different additives are added.

The object of the invention is completely achieved in this way.

According to the invention, a single-layer system is now used Headbox a targeted influence on the properties enables the pulp suspension in the z direction by different at different levels in the z direction Additives are added.

In this way, intensive washing out of fine and Fillers on the leaf surface and poor transport of fine and fillers from the middle of the sheet to the surface, which in the prior art always leads to a depletion of filler on the surface, be balanced.

Fillers or chemicals are used as additives, in particular retention agents or starch, if appropriate also Fibrous suspensions or mixtures thereof into consideration. The individual additives can differ due to their chemical composition, by their concentration or their physical State or distinguish their properties. There may also be different fiber suspensions Origin, such as from old paper or freshly made Suspensions are bleached or unbleached, wood-containing or wood-free or also to aggregates with artificial fibers produced, e.g. Trade plastic fibers. Besides additives that affect printability are special preferred, also substances that have mechanical properties, e.g. affect the firmness or a certain Generate shrinkage behavior, e.g. to create a bias are conceivable.

It is understood that the principles of the invention also apply to one multilayer headbox can be used advantageously can. Here, the properties of the manufactured Paper, particularly with regard to the production, is well printable and / or from highly filled papers to to produce papers with filler contents of at least 12%.

For this purpose, a fiber suspension is seen in the edge regions in the z direction fed, the better printability properties than the suspension fed in the middle of the sheet causes. It can be fiber suspension with higher Degree of grinding and / or with a higher filler or fine substance content act. In addition, a fiber suspension can be found in the middle of the sheet be fed, which causes a higher strength, thus more chemically digested fibers or stronger fibers contains.

This allows the printability and the mechanical properties optimally match the desired paper quality.

According to an advantageous development of the invention The process is seen less in the z direction towards the center of the sheet Retention agent metered in as in the edge areas of the fiber suspension.

In this way, a transport of fine and fillers relieved from the middle of the sheet to the surface and an increased Concentration of fine and fillers on the leaf surface enables.

In a further preferred embodiment of the invention in the z direction seen in the middle of the sheet less fillers and / or Fine substances metered in than in the peripheral areas.

Through these measures, a targeted on the leaf surface stronger concentration of fillers and / or fines and thus improved properties on the leaf surface will. So there can be a depletion of filler on the surface be counteracted, so far even when using a multi-layer headbox due to washout fear of fine and fillers on the leaf surface was.

In an additional development of the invention, the consistency the fiber suspension over the machine width, i.e. in y direction controlled zone by zone, while the zone by volume flows the fiber suspension kept essentially constant will.

According to this known method (compare e.g. EP 0 565 923 A1), it is possible in an advantageous manner Material density of the fiber suspension over the machine width targeted to influence while the fiber orientation cross profile is practically not affected.

It goes without saying that by adding additives the basis weight cross profile and the fiber orientation cross profile should not be influenced if possible.

For this reason, it is according to a further development of the invention provided that the volume flows of the added additives in each case by admixing an aqueous accompanying medium be kept constant.

This measure has the advantage that when the Amount of added additives the respective total flow, which is supplied via a metering line, kept constant and thus compensation currents in the nozzle in the transverse direction can be avoided if the amount of added additives is changed.

According to a further embodiment of the invention, the additives in the guide device, in the nozzle and / or metered in the distributor.

In this way, the properties can be influenced by the addition of different additives to particular targeted way at the required points be performed.

According to a further embodiment of the invention, the metering across the machine width in the y direction and / or in the z direction regulated by zones.

This measure has the advantage that the metered amount of each Aggregates optimally to the desired paper quality can be coordinated.

According to a further embodiment of the invention, a through the addition of aggregates across the machine width Change in basis weight caused in the y direction via a regulation of the material flow from the distributor and one mixed fiber suspension with a different concentration balanced.

Even if the volume flow of the added additives such as previously held constant, it will still run at a larger variation of the added additives if necessary affects the basis weight cross-section. This change is advantageously via a regulation of the material flow from the distributor and a mixed fiber suspension balanced with another concentration, so that despite a variation in the volume flow of individual aggregates desired basis weight cross profile can be maintained.

As seen in the y direction across the machine width in particular the mechanical paper properties at the edges can be worse, can in additional training the invention also in the y-direction in the edge regions different fiber suspensions or aggregates in other quantities or with different properties than in middle area are fed.

The object of the invention is also in a headbox solved according to the type mentioned in that in the area at least one layer of different metering lines on at least flow into two different levels in the z direction.

As previously mentioned, the metering lines can be in the Guide device, open into the nozzle and / or into the distributor.

In this way, targeted influencing can be carried out according to the invention the properties of the fiber suspension in the z direction achieve, for example, improved paper quality on the leaf surface even with a single layer To reach headbox.

According to a variant of the invention are downstream in the x direction seen several dosing lines arranged one behind the other.

This measure has the advantage that e.g. anionic and cationic Retention agents in the desired manner one after the other can be added to a particularly effective binding effect of the fine and fillers to reach the fibrils.

The guide device preferably comprises a pipe distributor or plate distributor trained turbulence generator. Turbulence generators of this type have become particularly practical proven.

In a further development of the invention is a control device to regulate the volume flow of the added additives provided, preferably one in the y direction and / or separate regulation of the supply of the aggregates in the z-direction enables.

In this way, a particularly targeted influence can be made the properties of the paper produced both in the y-direction as well as in the z direction.

According to a development of the invention is in the metering lines one device for adding an accompanying substance provided when changing the amount of aggregate in a dosing line keeping the Total volume flow guaranteed in the metering line.

In this way, the total volume flow in the metering line constant with a variation in the amount of aggregate are held so as to influence the fiber orientation cross profile to avoid.

In a preferred development of the invention, at least in the nozzle a slat is provided.

In addition, at least some of the metering lines can be used open out over the lamella.

In this way, the lamella itself can be used for targeted metering of aggregates can be used.

The object of the invention is also in a headbox for a paper machine with a distributor for distributing one Fibrous suspension over the machine width, that over a Guide device is connected to a nozzle from which the Fibrous suspension exits through a gap, the Headbox seen across the machine width a plurality of Sections includes, each of which via metering lines with control organs Aggregates, especially dilution water, about a plurality of outlet openings can be mixed locally, thereby solved that a plurality of sections each have their own Dosing line is assigned, which in a plurality of Line branches is divided with the outlet openings are connected.

Because here the outlet openings, which are in the distributor, the Guide device or in the nozzle of the headbox, directly via a line branch with the respective Aggregate are supplied, the pressure drop in the individual line branches significantly reduced since everyone Line branch directly connected to the source in question through which the aggregate is fed.

This results in a significantly lower pressure drop overall at different outlet openings, so that a total of one significantly more uniform section-wise admixture of the respective Aggregate is guaranteed.

In a further embodiment of the invention, at least one Dosing line the different line branches with one common regulatory body coupled.

This results in a particularly simple construction.

In an alternative embodiment there are at least one metering line a plurality of line branches each with one Provide control body.

In this way, a locally optimized setting of the Reach the amount of the additive mixed.

According to a further embodiment of the invention, at least open the different line branches in a metering line into the section from opposite sides.

In this way, the pressure drops are one after the other outlet openings provided on the line branches reduced because the line branches are not only from one side forth, but from two sides into the relevant section confluence, causing the amount of one line branch to supply outlet openings is reduced accordingly and so that the pressure loss is reduced accordingly.

Such an embodiment is particularly preferred if the different line branches from above and from below open the section, as with a step diffuser high number of rows may be the case of the different Line branches must be supplied.

This makes one largely, especially in the z direction enables even distribution of the admixed additives.

According to a further embodiment of the invention, at least open the different line branches in a metering line seen in the y direction side by side in the section.

In this way, a more even feed is created in one section of the additives to be supplied guaranteed.

According to a further embodiment of the invention, at least open the different line branches in a metering line Main flow direction seen in succession in the section a.

In this way, a particularly targeted dosage of additives to be mixed in the main flow direction.

In this case, targeted quantity control can be carried out in particular reach if the individual line branches each with their own Regulators are provided.

According to a further embodiment of the invention, the sections the additives to be mixed via the metering lines be trained, of different widths.

This measure has the advantage that the effort of the cable routing and the standard effort for the relevant sections the necessary resolution can be adjusted across the machine width can.

It is understood that the above and those below Features to be explained not only in each case specified combination, but also in other combinations or can be used alone, without the scope of to leave the present invention.

Fig. 1

eine erste Ausführung eines erfindungsgemäßen Stoffauflaufes in äußerst schematischer Darstellung;

Fig. 2

eine Abwandlung der Ausführung gemäß Fig. 1;

Fig. 3

eine weitere Abwandlung der Ausführung gemäß Fig. 1;

Fig. 4

eine nochmalige Abwandlung der Ausführung gemäß Fig. 1;

Fig. 5

eine schematische Darstellung zur Erläuterung des optimalen Einströmwinkels beim Mischen zweier Teilströme unter Konstanthaltung des Gesamtvolumenstroms;

Fig. 6

eine Aufsicht einer weiteren Ausführung eines erfindungsgemäßen Stoffauflaufes;

Fig. 7

eine Aufsicht einer Abwandlung der Ausführung gemäß Fig. 6;

Fig. 8

einen Dreischicht-Stoffauflauf, der für das erfindungsgemäße Verfahren verwendet werden kann.

Fig. 9

einen Längsschnitt durch eine weitere Ausführung eines Stoffauflaufs mit einer verbesserten Zufuhr für die Zudosierung der Zuschlagstoffe und

Fig. 10

einen Querschnitt durch einen Teil des Rohrverteilers oder Stufendiffusors gemäß Fig. 9 in schematischer Darstellung.

Further features and advantages of the invention result from the following description of preferred exemplary embodiments with reference to the drawing. Show it:

Fig. 1

a first embodiment of a headbox according to the invention in an extremely schematic representation;

Fig. 2

a modification of the embodiment of FIG. 1;

Fig. 3

a further modification of the embodiment of FIG. 1;

Fig. 4

a further modification of the embodiment according to FIG. 1;

Fig. 5

a schematic representation to explain the optimal inflow angle when mixing two partial flows while keeping the total volume flow constant;

Fig. 6

a supervision of another embodiment of a headbox according to the invention;

Fig. 7

a supervision of a modification of the embodiment of FIG. 6;

Fig. 8

a three-layer headbox that can be used for the inventive method.

Fig. 9

a longitudinal section through a further embodiment of a headbox with an improved feed for the addition of the additives and

Fig. 10

a cross section through part of the manifold or step diffuser according to FIG. 9 in a schematic representation.

In Fig. 1, a headbox according to the invention is shown schematically in Cross section shown and designated overall by the number 10.

The headbox 10 comprises a distributor 11, which acts as a cross-flow distributor is trained and in the direction of the material flow rejuvenated in a known manner. To the distributor 11 is followed by a guide device 12 which has a turbulence insert comprises, which as a pipe distributor (plate distributor) known design is formed. The pipe distributor 13 opens in a nozzle 14, at the front end of a gap 19 for exit the fiber suspension is formed.

The nozzle 14 can also be divided into several sections.

Both in the transition area between manifold 11 and pipe manifold 13, as well as in the manifold 13 as well as in the Nozzle 14 each open a plurality of metering lines 20, 21, 22 or 23, 24, 25 or 26, 27, 28 in which valves 29 are provided.

Although not apparent from the plane of the drawing according to FIG. 1, are across the machine width, i.e. seen in the y direction, each a plurality of such metering lines side by side arranged. The metering lines 20 - 22 or 23 - 25 or 26 - 28 each open at different levels in the z direction in the distributor 11 or in the pipe distributor 13 or into the nozzle 14. Thus, via the metering lines 20 - 28 specific at different points of the headbox Additives are added.

The substances added can be fillers, fibrous materials, Chemicals, especially retention agents, starch or also around fiber suspensions or mixtures of these dosing media act.

As indicated by the control device 18, the Dosing quantity of each individual dosing line 20 - 28 separately control, at the same time providing regulation in this way can be that optionally by admixing an aqueous Aggregate, e.g. of white water, the total volume flow each individual dosing line despite a change in the quantity of the added aggregate remains constant. In this way is avoided by varying the individual volume flows Equalization flows in the z direction in the nozzle 14 arise, leading to changes in the fiber orientation cross profile would lead.

The metering lines 20 - 28 can be used to target the center of the sheet less retention aids are dosed than in the peripheral areas. Furthermore, fewer fillers can be metered into the middle of the sheet are considered to be in the fringe areas. In this way, an increased Concentration of fine and fillers on the leaf surface supported. The high fines content in the A filter auxiliary layer through the fine and fillers be held on the surface. By the lesser The amount of retention agent in the middle of the leaf becomes less Binding effect of fine and fillers in this zone which causes the fibers to transport fine and fillers to the leaf surface is supported.

In addition, a can be seen in the edge areas in the z direction Fibrous suspension with a higher freeness than in the middle of the sheet be added.

However, an additional distributor is required for this, since the The degree of grinding of the fiber suspension is not achieved by adding a Aggregate can be changed.

This possibility is explained below with reference to FIG. 7.

In addition, the aforementioned variation in the aggregates or not only the degree of grinding of the fiber suspension in the z direction but also across the machine width in the y direction done to deteriorate properties in the Counteract marginal areas.

A modification of the embodiment according to FIG. 1 is shown in FIG. 2 and designated overall by the number 30.

Here too, the fiber suspension is used as a cross-flow distributor trained distributor 31 supplied and arrives from there via a guide device 32 into a nozzle 34, which exits through a gap 39. The leadership facility 32 comprises a first as a pipe or plate distributor 33 trained turbulence insert, to which a Mixing chamber 35 connects to the second as a pipe or Plate distributor 36 trained turbulence insert connects.

A lamella 37 is also provided in the nozzle 34, i.e. a slab across the width of the web leading into space protrudes the nozzle 34 and attached either horizontally or inclined is or articulated on its facing the plate distributor 36 End is attached.

A total of four metering lines 40-43 are shown in FIG. which protrude into the mixing chamber 35 and overall three metering lines 44 - 46, which are in the front part of the nozzle 34 protrude. The two metering lines 40, 41 are in Viewed in the direction of the current, arranged one behind the other and flow at the same level in the z direction at the top of the Mixing chamber 35. In contrast, the two following metering lines open 42, 43 at the lower end of the mixing chamber 35 on the same level. They are also in one after the other Flow direction arranged.

The three metering lines 44, 45, 46 open on different Levels in the z direction into the nozzle 34.

Again, there are 40-46 valves 49 in all metering lines provided to meter the additives in the desired manner to be able to.

Another modification of a headbox according to the invention is shown in Fig. 3 and generally designated by the number 50.

The fibrous suspension is in turn via an as Cross flow distributor trained distributor 51 supplied by from them via a guide device 52 in the form of a Pipe distributor 53 enters the nozzle 54, from which the fiber suspension flows out through the gap 59.

In Fig. 3 three metering lines 60-62 are shown, the at different levels in the z direction in the pipe distributor 53 flow into.

In the nozzle 54 are different from that previously described Execution now two superimposed slats 57, 58 provided, which are designed as hollow profiles with Dosing lines 63, 64 are connected so that via the dosing line 63, 64 added additives at the front of the Slats 57 and 58 can emerge.

It goes without saying that, as a modification of this, there is also an exit the top or bottom of the slats may be provided could.

Again, there are valves 69 to 64 in the metering lines for regulation intended.

Another modification of a headbox according to the invention is shown in Fig. 4 and generally designated by the numeral 70.

Again, the pulp suspension is used as a cross flow distributor trained distributor 71 fed and arrives from there via the guide device 72, which acts as a pipe distributor or plate distributor 73 is formed into the nozzle 74 which flows out through a gap 79.

4, three metering lines 80, 81, 82 are shown, the open into the manifold 73 and again from valves 89 are interrupted.

In contrast to the previously described designs, the Dosing lines 80 - 82 not vertically into the pipe distributor 73 one but at an obtuse angle chosen so that even with a change in the flow of the aggregates through the metering lines 80 - 82 the respective total volume flow through the relevant pipeline of the manifold 73 is not changed.

This measure has the advantage that regardless of the quantity of the added additives, the respective total volume flow not changed by the individual pipes of the manifold 73 is, so that despite a change in the amount of metered Aggregates in the nozzle 74 no equalizing flows arise can, so that the fiber orientation profile is not affected.

It is understood that keeping the individual volume flows constant through the metering lines 80 - 82, of course other ways can be achieved by appropriate control loops be provided or by an aqueous stream, in particular of white water, again at an appropriate angle is added so that the total volume flow through the respective metering lines 80 - 82 are not changed, if the individual dosing media are supplied in different quantities will.

5 shows a mixing device for mixing two volume flows shown as used according to EP 0 565 923 A1 can be.

The mixing device designated as a whole by the number 90 comprises a first pipe for carrying a main flow 92 in Direction of an arrow 93 into which a second pipe for guidance a side stream 96 in the direction of an arrow 95 with formation at an angle between the two pipes.

The one flowing into the main flow 92 in the direction of the arrow 95 Secondary flow 96 can be regulated via a valve 94.

The angle between the two streams 92, 96 is selected in such a way that even with a change in volume flow of the secondary flow 96 the total volume flow through the outlet end 98 largely unchanged. The angle is usually in the range between about 85 ° and 87 °. By an additional throttle point 97 after combining the main flow 92 and bypass flow 96, the desired linearity is improved.

Such mixing devices 90 are used to determine the basis weight cross-section to be able to regulate in the y direction like this is basically known from EP 0 565 923 A1 and below is explained with reference to FIG. 6.

6 shows a headbox according to the invention as a whole number 100.

The headbox 100 comprises a first distributor 101 for guidance a fiber suspension with a relatively high fiber concentration and a second distributor 106 with less Diameter in which white water is preferably led.

The second distributor 106 is via valves 107 and lines 108 each connected to a mixing device 109, which after the is constructed on the basis of FIG. 5 and in which Dilution water from the second distributor 106 in the volume flow is mixed from the first distributor 101, without this the total volume flow through the respective line 110 changes becomes. The mixing devices 109 are via the lines 110 connected to a subsequent guide device 102, which in turn connects to the nozzle 104. The leadership facility 102 in turn comprises a plate distributor Pipe distributor 103, in the metering lines 111, 112, 113 merge at different levels in the z direction to different To be able to add additives.

Finally, the fibrous web 105 emerges from the nozzle 104.

6, the basis weight cross-section can can be influenced in the desired manner without the fiber orientation cross profile is adversely changed. At the same time, additives can be added via the metering lines 111 - 113 can be added in the desired manner to add properties in the z-direction or y-direction.

7 shows a further modification of an inventive one Headbox shown and generally designated by the number 120.

7 differs from that previously 6 described embodiment in that in addition to the two distributors for the fiber suspension high concentration and for the fiber suspension with low Concentration (white water) provided a third distributor is about the targeted dosing of fiber suspensions with a higher or lower grinding degree.

A first distributor 121 serves for the main supply of the headbox 120 in the middle area except the edge zones in the y direction seen. This distributor 121 becomes a fiber suspension fed with a relatively low degree of grinding.

Another distributor 137 is used to supply fiber suspension with a higher degree of grinding, preferably in the peripheral areas is fed.

A third distributor 126 is used to supply white water for diluting those from the first distributor 121 or the second Distributor 137 branched fiber suspension. The third Distributor 126 is in turn via valves 127 and lines 128 connected to mixing devices 129, the fiber suspension is fed from the second distributor 137, or via Valves 127 and lines 131 connected to mixing devices 132, those fiber suspension from the first distributor 121 is fed.

The mixing devices 129 and 132 are finally via lines 130 or 133 connected to the pipe distributor 123.

Thus, seen in the y direction in the edge areas of the Fibrous web 125 is a fibrous suspension with a higher freeness feed as in the central area that from the first distributor 121 is supplied.

Again, aggregates can be fed through metering lines 134-136 are metered into the pipe divider 123 at different levels, to specifically influence the properties of the fibrous web 125 to achieve.

8 is a three-layer headbox for executing the illustrated method and overall with the Number 140 denotes.

The headbox 140 includes a first manifold 141 for receiving of high concentration pulp suspension for regulation of the consistency cross section from a secondary distributor 142 via valves 143 and lines 144 via mixer devices 145 with throttling points 146 lower fiber suspension Concentration, e.g. White water is added. Two more Distributors 148 and 150 are for receiving fiber suspension provided that fed into the upper and lower edge areas is targeted to the printability in the marginal areas to improve. The three fiber suspensions will be via lines 147, 149, 151 and guide devices 152 in Nozzles 154 guided, from which they form a column Fibrous web 155 between a lower one via a wire guide roller 156 guided screen 157 and an upper one Screen guide roller 158 guided screen 159 are imposed.

9 shows another headbox according to the invention for a paper machine designated overall by the number 210.

The headbox 210 comprises a cross-distributor Distributor 212, which has a guide device 214 a nozzle 218 is connected, from which the fiber suspension supplied exits through a machine-wide gap 220.

The guide device 214 comprises a pipe distributor 16 or Step diffuser with a variety of tubes, the structure of which the sectional view of FIG. 10 can be seen in more detail.

The headbox 210 is divided over the machine width (y direction) into a plurality of sections S ₁ , S ₂ , S ₃ , .., as can be seen from FIG. 10.

An aggregate is regulated for each individual section, in particular Dilution water, admixed so as to enable local consistency control without the gap 220 being adjusted must become.

9, three are exemplary for a single section Dosing lines provided with different outlet openings in manifold 212, in manifold 216 and in open the nozzle 218.

Since each metering line 222, 234, 248 has a plurality of outlet openings the metering lines 222, 234, 248 divided into individual line branches in order to reduce the pressure loss to keep it smaller at the outlet openings and so one more uniform distribution of the aggregate in the z direction to ensure.

The first metering line 222, which is in the transition area between Distributor 212 and pipe distributor 216 opens out of one common feed line 226 fed with white water and is about a common regulator that is controllable as a motor Valve can be designed, adjustable. The dosing line 222 is divided into two line branches 228, 230, the bottom and from above into the transition area between distributors 212 and pipe manifold 216 open and the ends of one closed loop are connected. The dilution water passes through several outlet openings arranged one above the other in the z direction from which three exit openings are exemplary 231, 232, 233 are shown.

By dividing the metering line 222 into two line branches, those from opposite sides the one behind the other arranged outlet openings 231, 232, 233 will supply the pressure loss is significantly reduced and an even distribution of the dilution water in the z direction.

The second metering line 234 becomes a feed line 238 fed with dilution water, whose volume flow over a common regulator 236 can be regulated. According to the regulatory body 236 is the metering line 234 via a distributor 235 in three individual line branches 240, 242, 244 divided, one after the other seen in the x direction at different levels in the z direction open into the manifold 216 and from which the Dilution water emerges through outlet openings from which the outlet openings 245, 246, 247 are shown as examples are.

The third metering line 248 is in turn made up of a common one Feed line 256 powered, but includes the metering line 248 three completely separate line branches 258, 260, 262, each with a control unit 250, 252, 254 with the feed line 256 are connected and at their lower ends open at different levels in the nozzle 218 to dilution water via outlet openings, of which the example Outlet openings 263, 264, 265 are shown on different To be able to feed in levels in the z direction.

10 shows a section of a pipe distributor in an enlarged view Representation shown in cross section. The pipe distributor or step diffuser consists of a large number of individual tubes, which are in the main flow direction, i.e. extend in the x direction and expand gradually in the x direction. In the z direction dosing lines are provided to dilution water to be able to mix.

Like the entire headbox, the pipe distributor is divided into individual sections S ₁ , S ₂ , S ₃ , .., viewed in the y direction, which can be individually controlled to enable local consistency control over the machine width. A section S ₁ , S ₂ is supplied with dilution water by a metering line 282, 284. Each metering line 282, 284 is divided into two line branches 266, 268 and 286, 288, which open into the pipe distributor from above and from below. The line branches are each divided into two sub-strands within the pipe distributor themselves, which extend in the z-direction between the individual pipes 270, as exemplified by the sub-strands 274, 276, and from which dilution water via outlet openings 272 into the pipes 270 des Pipe distributor passes.

Because the dilution water comes from above and from below via the sub-branches of the respective metering line into the pipe distributor is supplied, as indicated by the arrows 278, 280 is the total within each metering line 282 or 284 a significantly reduced pressure drop along the Way through the manifold, as compared to conventional Dosing lines that only come from above or from below with one Open the line branch in the pipe distributor, the amount of halved via an outlet openings to be supplied is.

Furthermore, the opposite direction of flow results in two sides ago a further equalization of the amount of admixed fluids seen in the z direction.

It goes without saying that this version is of course also special advantageous for the supply of the additives in the form of Fillers, chemicals, especially retention aids, starch, Fibrous suspensions or the like, or mixtures thereof, at different levels in the z direction for targeted influencing the paper properties can be used. For this purpose, the metering lines 258, 260, 262, the different levels in the z direction open into the nozzle 218, formed as ring lines in individual sections be fed from individual distributors. This version can also be used with the previously mentioned versions can be combined, i.e. only for the supply of dilution water used while additionally different Additives are added in the z direction.

Claims (26)

Process for the distribution of a fiber suspension in the Headbox of a paper machine in which the fiber suspension from at least one distributor (11, 31, 51, 71, 101, 106, 121, 126, 137, 141, 142, 148, 150) a guide device (12, 32, 52, 72, 102, 122, 152) into a nozzle (14, 34, 54, 74, 104, 124, 154) from which it emerges via a gap (19, 39, 59, 79), characterized in that the fibrous suspension on at least two different levels Different additives are added in the z direction will. A method according to claim 1, characterized in that as additives, fillers, chemicals, in particular Retention agent, starch, fiber suspension, or mixtures of which are added. Method according to one or more of the preceding claims, characterized in that seen in the z direction less retention aid is metered into the middle of the leaf is considered in the edge areas of the fiber suspension. Method according to one or more of the preceding claims, characterized in that seen in the z direction less fillers and / or fines in the middle of the sheet are added as in the peripheral areas. Method according to one or more of the preceding claims, characterized in that seen in the z direction additives are metered into the middle of the sheet, which increase the strength, and that in the marginal areas Additives are added, which increase the printability improve. Method according to one or more of the preceding claims, characterized in that the consistency of the Pulp suspension across the machine width (y direction) is regulated by zones, while the zones Volume flows of the fiber suspension essentially be kept constant. Method according to one or more of the preceding claims, characterized in that the volume flows of the added additives in each case by admixing of an aqueous accompanying medium can be kept constant. Method according to one or more of the preceding claims, characterized in that the aggregates in the guide device (12, 32, 52, 72, 102, 122, 152), in the nozzle (14, 34, 54, 154) and / or in the distributor (11, 141, 148, 150) are added. Method according to one or more of the preceding claims, characterized in that the metering over the machine width (y direction) and / or in the z direction is regulated zone by zone. Method according to one or more of the preceding claims, characterized in that one by the metering of aggregates across the machine width (y direction) caused change in basis weight via a regulation of the material flow from the distributor (101, 121, 137, 141) and a mixed fiber suspension is balanced with a different concentration. Process for the distribution of a fiber suspension in a multi-layer headbox of a paper machine, in which the fiber suspension from at least two distributors (11, 31, 51, 71, 101, 106, 121, 126, 137, 141, 142, 148, 150) via guide devices (12, 32, 52, 72, 102, 122, 152) in nozzles (14, 34, 54, 74, 104, 124, 154), from which it is displayed via columns (19, 39, 59, 79) emerges, especially after one or more of the previous ones Claims, characterized in that in the z direction seen in the edge areas a fiber suspension with a higher degree of grinding, with a higher filler or Proportion of fines, or with less chemically digested and stronger fibers than in the middle of the sheet becomes. A method according to claim 11, characterized in that Seen in the y direction, a fiber suspension in the edge areas with different properties than in the Middle of the sheet is fed. Method according to one or more of the preceding claims, characterized in that seen in the y direction in the middle of the leaf aggregates in other quantities or with other properties than in the border areas be added to the fiber suspension. Headbox for a paper machine with a distributor (11, 31, 51, 71, 101, 106, 121, 126, 137, 141, 142, 148, 150) for distributing a fiber suspension over the Machine width, which is guided by a guide device (12, 32, 52, 72, 102, 122, 152) with a nozzle (14, 34, 54, 74, 104, 124, 154) is connected, from which the fibrous suspension exits through a gap (19, 39, 59, 79), and with a metering device with metering lines (20-28, 40-46, 60-64, 80-82, 111-113, 134-136) for metering of aggregates, characterized in that different dosing lines on at least two different ones Merging levels in the z direction. Headbox according to claim 14, characterized in that the metering lines (20-28, 40-46, 60-64, 80-82, 111-113, 134-136) into the guide device (12, 32, 52, 72, 102, 122), into the nozzle (14, 34, 54, 74, 104, 124) and / or in the distributor (11, 31, 51, 71, 101, 106, 121, 126, 137). Headbox according to claim 15, characterized in that downstream (seen in the x direction) several metering lines (40, 41, 42, 43) arranged one behind the other are. Headbox according to one or more of claims 14 to 16, characterized in that a control device (18) to regulate the volume flow of the added additives is provided, which is preferably in the y direction and / or separate regulation of the z-direction Allows the addition of additives. Headbox according to one or more of claims 14 to 17, characterized in that in the nozzle (34, 35) at least one lamella (37, 57, 58) is provided, and that at least some of the metering lines (63, 64) over open the lamella (57, 58). Headbox for a paper machine with a distributor (212) for distributing a fiber suspension over the machine width, which is connected via a guide device (214) to a nozzle (218) from which the fiber suspension exits via a gap (220), the headbox via seen the machine width (y-direction) comprises a plurality of sections (S ₁ , S ₂ , S ₃ ), each of which has metering lines (222, 234, 248, 282, 284) with control elements (224, 236, 250, 252, 254) additives, in particular dilution water, can be admixed locally via a plurality of outlet openings (231, 232, 233, 245, 246, 247, 263, 264, 265, 272), in particular according to one of claims 14 to 18, characterized in that one A plurality of sections (S ₁ , S ₂ , S ₃ ) each has its own metering line (222, 234, 248, 282, 284) which is divided into a plurality of line branches (228, 230, 240, 242, 244, 258, 260, 262, 266, 268, 286, 288), which mi t the outlet openings (231, 232, 233, 245, 246, 247, 263, 264, 265, 272) are connected. Headbox according to claim 19, characterized in that in at least one metering line (222, 234) the different Line branches (228, 230, 240, 242, 244) with a common control element (224, 236) are coupled. Headbox according to claim 19 or 20, characterized in that in at least one metering line (222, 282, 284) the different line branches (228, 230, 266, 268, 286, 288) from opposite sides into the section (S ₁ , S ₂ , S ₃ ) lead into. Headbox according to claim 21, characterized in that in at least one metering line (222, 282, 284) the different line branches (228, 230, 266, 268, 286, 288) from above and from below into the section (S ₁ , S ₂ , S ₃ ) lead into. Headbox according to one or more of claims 14 to 22, characterized in that at least one Dosing line the various line branches in the y direction seen flowing into the section side by side. Headbox according to one or more of claims 14 to 23, characterized in that, in the case of at least one metering line (234, 248), the different line branches (240, 242, 244) one behind the other in the main flow direction (x direction) into the section (S ₁ , S ₂ , S ₃ ) merge. Headbox according to one or more of claims 14 to 24, characterized in that at least one Dosing line (248) a plurality of line branches (258, 260, 262) each with a control element (250, 252, 254) is provided. Headbox according to one or more of claims 14 to 25, characterized in that the sections differ are wide.

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