DE102004056033A1 - Material supplier for machine for producing fibrous sheets, especially of paper or cardboard, having distributor with tubular body and mixer to give even distribution of fiber suspension over machine widfh - Google Patents

Abstract

In a material supplier (1) for a fibrous sheet production machine having a device (2) for distributing a fibrous material suspension (3) in partial streams over the width (M) of the machine, the distributor (2) is in the form of a linear tubular body (11) and is arranged in series in the machine running direction with a mixer (12) for evening the flow distribution over the machine width. In a material supplier (1) for a fibrous sheet production machine, having a device (2) for distributing a fibrous material suspension (3) in partial streams over the width (M) of the machine, with a turbulence inducer (5) and a material supply nozzle (6) (having an outlet gap providing a jet (8) of fibrous material suspension) arranged in series in the machine running direction (L), the distributor (2) is in the form of a linear (preferably at least approximately cylindrical) tubular body (11) and is arranged in series in the machine running direction with a mixer (12) for evening the flow distribution over the machine width.

Description

The The invention relates to a headbox for a machine for manufacturing a fibrous web, in particular a paper or board web, with at least one distribution device for distributing a pulp suspension in partial streams over the Machine width, which in the machine direction a turbulence generator and a headbox downstream that is with a fibrous suspension jet delivering Exit gap is provided.

Such a headbox is for example from the European patent specification EP 0 708 201 B1 known.

One essential quality factor a fibrous web, in particular a paper or board web, lies in the uniformity properties, such as basis weight or formation, the manufactured track. This uniformity of properties can only be ensured if a uniform and constant flow through the Headbox is given. An important prerequisite for this is one Pressure equal distribution of the pulp suspension in the distribution device in the form of a round, rectangular or polygonal distribution tube. The one for it necessary parabolic shape of the manifold with decreasing clear width is very expensive to manufacture. There have to be many small Blechabwicklungen made, welded together and finally sanded become. Thus, the distribution devices currently in use are in the form of a parabolic manifold very expensive in production, procurement and, if necessary, the case a repair. moreover is a parabolic manifold usually only for one designed specific operating point, while the continuous Deduction of Fasestoffsuspension and friction losses for the purpose of Pressure equal distribution of the pulp suspension in the distributor tube taken into account become.

Farther a distributor in the form of a tubular body is known. The tube body points a preferably rectangular cross section, which is usually longitudinal of the tubular body rejuvenated. Such a distributor is usually used as a rectangular distributor designated. Among other things, it has the disadvantage of a fluidic not optimal geometry.

Although it is also a distribution device in the form of a rotary distributor known, for example from the German patent DE 40 05 281 C2 , However, this type of distribution device is not always usable because of its space requirement. In addition, the operating and maintenance costs of a rotary distributor are not exactly negligible.

It So is the object of the invention, a headbox of the beginning to create the type mentioned, the uniformity of the properties of a produced fibrous web using a simplified and thus cheaper Distributor allows.

These Task is solved in a headbox, characterized in that the distribution device the shape of a linear, preferably a cylindrical or approximately cylindrical tubular body and that the distributor in the machine direction a mixing device for equalizing the machine widths flow distribution the pulp suspension is connected downstream.

Of the Headbox according to the invention Ensures that when using a simple and inexpensive Distributor tube in the form of a linear tube body equalization of Machine width flow distribution the pulp suspension due to the use of the mixing device guaranteed is.

Of the pipe body in this case preferably has a cylindrical or approximately cylindrical Contour on. However, the tubular body may also have a conical contour exhibit.

The Mixing device preferably comprises a plurality of transversely to the machine direction arranged side by side and preferably by a respective partial flow flowed through mixing units that equalize the Machine width flow distribution the pulp suspension due to different pressure losses and velocities in the partial streams of pulp suspension effect in the individual mixing units.

In this case, the mixing units advantageously each have a flow channel whose lateral wall plates are at least partially formed as structural plates which have a turbulence-generating corrugated surface structure. This surface structure causes in each case a pressure drop and a decrease in speed in the flowing pulp suspension with the aim of equalizing the machine-width flow distribution of the pulp suspension. This achieves a similar effect as using a parabolic manifold. The change in the downstream pressure loss on the structural plates is proportional to the width of the flow channel and approximately with calculate the following formula:

Where Δp is the pressure drop, ρ is the density, V _is the manifold velocity, λ is the resistance, ALB is the outlet _width , Φ _is the manifold diameter and μ is the recirculation number.

The Structural plates of the mixing units are in a preferred embodiment of Distributor immediately downstream in the machine direction. Farther can they are displaceable in the machine direction, whereby an optimal Adjustment of the mixing device to different operating points is made possible.

Further they pass through the surface structure the structure plates formed waves perpendicular or approximately perpendicular or at an angle <90 ° to the machine direction. This results in turn different and preferably adjustable flow conditions with the aim of the already mentioned equalization of the machine widths flow distribution the pulp suspension.

The Structural plates each have a wave amplitude in the range of 0.1 to 0.5 x pitch of the mixing units, preferably from 0.3 to 0.5 x division of the mixing units, and one wavelength in each case from 1 to 4 x wave amplitude, preferably from 1.5 to 2.5 x wave amplitude, on.

• – die Strukturplatten einer Mischeinheit weisen eine jeweilige Plattenlänge auf, die quer zur Maschinenlaufrichtung gleich bleibende oder größer werdende Werte annimmt;
• – die Strukturplatten einer Mischeinheit weisen einen jeweiligen Plattenabstand auf, der quer zur Maschinenlaufrichtung gleich bleibende oder kleiner werdende Werte annimmt, wobei die Mischeinheiten bevorzugt eine Teilung aufweisen, die quer zur Maschinenlaufrichtung einen gleichen oder annähernd gleichen Wert annimmt, und die Strukturplatten einer Mischeinheit bevorzugt eine jeweilige Plattendicke aufweisen, die quer zur Maschinenlaufrichtung gleich bleibende größer werdende Werte annimmt; und/oder
• – die Wellenlängen und/oder die Wellenamplituden der Strukturplatten der Mischeinheiten und/oder der Mischeinrichtung sind verschieden.

For the best possible equalization of the machine-width flow distribution of the pulp suspension various possibilities are provided, both alone and in combination with each other:

• The structural plates of a mixing unit have a respective plate length which assumes values which increase or increase transversely to the machine direction;
• The structural plates of a mixing unit have a respective plate spacing which assumes constant or decreasing values transversely to the machine direction, the mixing units preferably having a pitch which assumes an equal or approximately equal value transverse to the machine direction, and the pattern plates of a mixing unit preferably one have respective plate thickness, which assumes transverse to the machine direction constant increasing values; and or
• - The wavelengths and / or the wave amplitudes of the structural plates of the mixing units and / or the mixing device are different.

Of course, at least these possibilities preferably be combined with each other as desired. The goal of a However, individual combination is always the equalization of Machine width flow distribution be the pulp suspension.

In order to in particular optimizes the fiber orientation profile of the fibrous web can be between the mixer and the turbulence generator in the machine direction preferred at least one dilution device, in particular a Siebwasserdosiereinrichtung, the more across the Machine direction comprises juxtaposed mixing chambers, each partial streams different consistency fed are each and provide a mixed stream, and a machine width Intermediate chamber, which receives the respective mixed streams arranged.

The diluter preferably has at least one second distribution device for distribution a low-consistency pulp suspension, in particular of White water, over the machine width on. This ensures the greatest possible flexibility of the dilution water system reached.

Farther the dilution device is preferred a pitch equal to that of the mixing units. This is a good aerodynamic Matching the headbox while evening the machine widths Flow distribution of Pulp suspension possible.

Also can still between the mixing device and the dilution device be arranged machine-width intermediate chamber, the desired homogenization positive supported.

Of the Headbox according to the invention Depending on the intended use, it can also be used as a multi-layer casserole accomplished be.

Further Features and advantages of the invention will become apparent from the following Description of preferred embodiments with reference to the drawing.

It demonstrate

1 a schematic longitudinal view of a head box according to the invention for a machine for producing a fibrous web;

2 and 3 two sectional views of two inventive headboxes in the region of the distributor and the mixing device according to the section line AA of 1 ;

4 and 5 two sectional views each of a mixing unit of a mixing device according to the section line BB of 1 ; and

6 : A side view of a structural plate of a mixing unit.

The 1 shows a schematic longitudinal view of a head box according to the invention 1 for a machine for producing a fibrous web, in particular a paper or board web.

The headbox 1 includes at least one distribution device 2 for distributing a pulp suspension 3 in sub-streams 4 across the machine width M (arrow). The distribution device 2 is a turbulence generator in the machine direction L (arrow) 5 and a headbox nozzle 6 downstream with a pulp suspension jet 8th supplying exit gap 7 is provided. The turbulence generator 5 generally has a plurality of turbulence channels 9 on and in the headbox 6 are in the execution of the headbox 1 according to the 1 two slats 10 arranged. Of course, in the headbox 6 also more than two slats 10 be arranged, for example between each row of turbulence channels 9 , Also, the slats can 10 have different lamellae L _L so that they within the headbox 6 , in the area of the exit gap 7 or outside the headbox nozzle 6 end up.

The distribution device 2 has the shape of a cylindrical or approximately cylindrical tubular body 11 on and it is in the machine direction L (arrow) a mixing device 12 to even out the machine-width flow distribution of the pulp suspension 3 downstream.

The execution of the headbox 1 according to the 1 includes one between the mixing device 12 and the turbulence generator 5 in the machine direction L (arrow) arranged and preferably controllable / dilution device 13 , in particular a Siebwasserdosiereinrichtung, the several transverse to the machine direction L (arrow) juxtaposed mixing chambers 14 comprises, to each of which partial streams Q _TV1 to Q _{TVN of} different consistency c _V1 to C _{VN can be} fed and which each provide a mixed stream Q _M1 to Q _MN , and a machine-wide intermediate chamber 15 , which receives the respective mixed streams Q _M1 to Q _MN , are arranged. The dilution device 13 has at least one second distribution device 16 for distributing a low-consistency pulp suspension in partial streams Q _TV1 to Q _TVN , in particular white water, across the machine width M (arrow). The dilution device 13 , the mixing chambers 14 , the intermediate chamber 15 and the second distribution device 16 are only shown in dashed lines. If these assemblies are not present, then the turbulence generator can 5 to the mixing device 12 extend.

A headbox with a sectioned consistency control (dilution water technology, "ModuleJet") for setting the basis weight cross profile is for example from the German patent DE 40 19 593 C2 known.

Between the mixing device 12 and the dilution device 13 can also be a dashed shown and machine-wide intermediate chamber 17 be arranged.

The headbox according to the invention 1 In a further embodiment, it is of course also possible to design it as a multilayer headbox known to the person skilled in the art.

The 2 and 3 show two sectional views of two inventive headboxes 1 in the area of the distribution device 2 and the mixing device 12 according to the section line AA of 1 ,

The distribution device 2 has, as already described, the shape of a cylindrical or approximately cylindrical tubular body 11 on. In machine direction L (arrow) it is a mixing device 12 to even out the machine-width flow distribution of the pulp suspension 3 downstream. The feed of the pulp suspension 3 and the expiration of the excess pulp suspension 3 are each shown with an arrow. Furthermore, an exemplary conical contour of the tubular body 11 indicated by dashed lines.

It can also be seen in both figures that the respective mixing device 12 a plurality of transversely to the machine direction L (arrow) arranged side by side and preferably flowed through by a respective partial flow Q _T1 to Q _TN mixing units 18 includes an equalization of the machine-width flow distribution of the pulp suspension 2 as a result of different pressure losses Δp ₁ to Δp _N and speeds v ₁ to v _N in the partial flows Q _T1 to Q _{TN of} the pulp suspension 2 in the individual mixing units 18 cause.

The mixing units 18 So each have a flow channel 19 on, whose side wall plates 20 at least partially as preferably in the machine direction L (arrow) movable structural plates 21 are formed, which is a turbulence generating corrugated surface structure 22 exhibit. The structural plates 21 of the mixing units 18 are the distributor 2 in the machine direction L (arrow) immediately downstream. However, you can also go to the distribution facility 2 be spaced apart.

Furthermore, the mixing units 18 a pitch T _M , which assumes an equal or approximately equal value transversely to the machine direction L (arrow). In addition, the dilution device, not shown, has 13 preferably a pitch T _V on that of the pitch T _{M of} the mixing units 18 equivalent. However, it is also understood that the pitch T _M transversely to the machine direction L (arrow) assumes different values. The various values may, if appropriate, run periodically.

So that now a homogenization of the machine width flow distribution of the pulp suspension 2 as a result of different pressure losses Δp ₁ to Δp _N and speeds v ₁ to v _N in the partial flows Q _T1 to Q _{TN of} the pulp suspension 2 in the individual mixing units 13 causes the structural plates 21 a single mixing unit 18 of the 2 a respective plate length L _P , at a constant or approximately constant pitch T _{M of} the mixing units 18 transverse to the machine direction L (arrow) assumes increasing values. In this case, the respective plate spacing A _{P of} the pattern plates increases 21 Transverse to the machine direction L (arrow) constant values. The structural plates 21 a single mixing unit 18 have a respective plate thickness D _P , which assumes transverse to the machine direction L (arrow) constant values. The structural plates 21 Thus, transverse to the machine direction L (arrow), the length of the wall plates is increasingly approaching 20 at. The illustrated course of the plate length L _P has only an exemplary character; he can depending on the configuration of the distribution device 2 also assume a wave-shaped course.

For the purpose of said homogenization, the structural plates 21 a single mixing unit 18 of the 3 a respective plate spacing A _P , which at constant or approximately constant pitch T _{M of} the mixing units 18 transverse to the machine direction L (arrow) assumes decreasing values. For this purpose, the structure plates 21 a single mixing unit 18 a respective plate thickness D _P , which assumes transverse to the machine direction L (arrow) increasing values. The structural plates 21 So all have the same plate length L _P , which in this embodiment is equal to the plate length L _{W of} the wall panels 20 is.

The 4 and 5 show two sectional views of a mixing unit 18 a mixing device 12 according to the section line BB of 1 ,

The respective mixing unit 18 Thus, as already mentioned, has a flow channel 19 on, whose side wall plates 20 at least partially as preferably in the machine direction L (arrow) movable structural plates 21 are formed, which is a turbulence generating corrugated surface structure 22 exhibit.

The two in the 4 and 5 illustrated mixing units 18 have structure plates 21 different wavelength W _L and / or wave amplitudes W _A on. The structural plates 21 of the 4 have large wavelengths W _L and small wave amplitudes W _A , whereas the pattern plates 21 of the 5 have small wavelengths W _L and large wave amplitudes W _A. As a rule, the at least two structural plates 21 a mixing unit 18 the same geometries; however, they can be different. This also applies to those from a large number of mixing units 18 formed mixing device 12 ,

The structural plates 21 each have a wave amplitude W _A in the range of 0.1 to 0.5 x pitch T _{M of} the mixing units 18 , preferably from 0.3 to 0.5 x pitch T _{M of} the mixing units 18 , and in each case a wavelength W _L in the range of 1 to 4 x wave amplitude W _A , preferably of 1.5 to 2.5 x wave amplitude W _A , on.

The through the surface structure 22 the structural plates 21 formed waves are perpendicular or approximately perpendicular to the machine direction L (arrow).

Like in the 5 is shown, the geometry within a mixing unit 18 not necessarily symmetrical. The possible asymmetry of the structural plates 21 is represented by a dashed upper structural plate.

The 6 shows a side view of a structural plate 21 a mixing unit 18 ,

The through the surface structure 22 the structural plate 21 formed waves extend at an angle α <90 ° to the machine direction L (arrow).

In summary It should be noted that a headbox of the invention is created in the aforementioned type, the uniformity of the Properties of a manufactured fibrous web when using a simplified and thus more cost-effective Distributor allows.

1

headbox

2

distributor

3

Fibrous suspension

4

partial flow

5

turbulence generator

6

headbox

7

exit slit

8th

Fibrous suspension beam

9

turbulence channel

10

lamella

11

pipe body

12

mixing device

13

diluter

14

mixing chamber

15

intermediate chamber

16

Second distributor

17

intermediate chamber

18

mixing unit

19

flow channel

20

wall plate

21

structural panel

22

surface structure

A-A

intersection

A _p

plate spacing

B-B

intersection

c _V1 to c _VN

consistency (Dilution)

D _P

plate thickness

L

Machine direction (Arrow)

L _L

lamellar length

L _P

panel length

M

machine width (Arrow)

Q _M1 to Q _MN

mixed stream

Q _T1 to Q _TN

partial flow

Q _TV1 to Q _TVN

partial flow (Dilution)

T _M

division (Mixing unit)

T _V

division (Dilution means)

v ₁ to v _N

speeds

W _A

wave amplitude

W _L

wavelength

Δp ₁ to Δp _N

pressure drop

Claims (17)

Headbox ( 1 ) for a machine for producing a fibrous web, in particular a paper or board web, with at least one distributor device ( 2 ) for distributing a pulp suspension ( 3 ) in sub-streams ( 4 ) across the machine width (M), in the machine direction (L) a turbulence generator ( 5 ) and a headbox nozzle ( 6 ), which has been treated with a fibrous suspension jet ( 8th ) delivering exit slit ( 7 ), characterized in that the distribution device ( 2 ) the shape of a linear, preferably a cylindrical or approximately cylindrical tubular body ( 11 ) and that the distribution device ( 2 ) in the machine direction (L) a mixing device ( 12 ) for equalizing the machine-width flow distribution of the pulp suspension ( 3 ) is connected downstream. Headbox ( 1 ) according to claim 1, characterized in that the mixing device ( 12 ) a plurality of transversely to the machine direction (L) arranged side by side and preferably of each a partial flow (Q _T1 to Q _TN ) through which flow mixing units ( 18 ), which is an equalization of the machine-width flow distribution of the pulp suspension ( 3 ) due to different pressure losses (Δ _P1 to Δ _PN ) and velocities (v ₁ to v _N ) in the partial flows (Q _T1 to Q _TN ) of the pulp suspension ( 3 ) in the individual mixing units ( 18 ) cause. Headbox ( 1 ) according to claim 2, characterized in that the mixing units ( 18 ) each have a flow channel ( 19 ) whose lateral wall plates ( 20 ) at least in regions as structural plates ( 21 ), which form a turbulence-generating corrugated surface structure ( 22 ) exhibit. Headbox ( 1 ) according to claim 3, characterized in that the structural plates ( 21 ) of the mixing units ( 18 ) of the distribution device ( 2 ) are immediately downstream in the machine direction (L). Headbox ( 1 ) according to claim 3 or 4, characterized in that the structural plates ( 21 ) of the mixing units ( 18 ) are displaceable in the machine direction (L). Headbox ( 1 ) according to any one of claims 3 to 5, characterized in that the surface texture ( 22 ) of the structural plates ( 21 ) formed perpendicular or approximately perpendicular to the machine direction (L). Headbox ( 1 ) according to any one of claims 3 to 5, characterized in that the surface texture ( 22 ) of the structural plates ( 21 ) formed at an angle (α) <90 ° to the machine direction (L). Headbox ( 1 ) according to one of claims 3 to 7, characterized in that the structural plates ( 21 ) each have a wave amplitude (W _A ) in the range of 0.1 to 0.5 x pitch (T _M ) of the mixing units ( 18 ), preferably from 0.3 to 0.5 x pitch (T _M ) of the mixing units ( 18 ), and each having a wavelength (W _L ) in the range of 1 to 4 x wave amplitude (W _A ), preferably from 1.5 to 2.5 x wave amplitude (W _A ), have. Headbox ( 1 ) according to one of claims 3 to 8, characterized in that the structural plates ( 21 ) a mixing unit ( 18 ) have a respective plate length (L _P ), which assumes transversely to the machine direction (L) constant or increasing values. Headbox ( 1 ) according to one of claims 3 to 9, characterized in that the structural plates ( 21 ) a mixing unit ( 18 ) have a respective plate spacing (A _P ), which assumes transversely to the machine direction (L) constant or decreasing values. Headbox ( 1 ) according to claim 10, characterized in that the mixing units ( 18 ) have a pitch (T _M ) which assumes an equal or approximately the same value transversely to the machine direction (L), and in that the structural plates ( 21 ) a mixing unit ( 18 ) have a respective plate thickness (D _P ), the transversely to the machine direction (L) assumes constant increasing values. Headbox ( 1 ) according to one of claims 3 to 11, characterized in that the wavelengths (W _L ) and / or the wave amplitudes (W _A ) of the structural plates ( 21 ) of the mixing units ( 18 ) and / or the mixing device ( 12 ) are different. Headbox ( 1 ) according to one of the preceding claims, characterized in that between the mixing device ( 12 ) and the turbulence generator ( 5 ) in the machine direction (L) at least one dilution device ( 13 ), in particular a Siebwasserdosiereinrichtung, the several transverse to the machine direction (L) juxtaposed mixing chambers ( 14 ), to each of which substreams (Q _TV1 to Q _TVN ) of different consistency (c _V1 to c _VN ) can be fed and which each provide a mixed stream (Q _M1 to Q _MN ), and a machine-wide intermediate chamber ( 15 ) accommodating the respective mixed streams (Q _M1 to Q _MN ) are arranged. Headbox ( 1 ) according to claim 13, characterized in that the dilution device ( 13 ) at least one second distribution device ( 16 ) for distributing a low consistency pulp suspension ( 3 ), in particular white water, across the machine width (M). Headbox ( 1 ) according to claim 13 or 14, characterized in that the dilution device ( 13 ) has a pitch (T _V ) equal to that of the mixing units ( 18 ) corresponds. Headbox ( 1 ) according to one of claims 13 to 15, characterized in that between the mixing device ( 12 ) and the dilution device ( 13 ) a machine-wide intermediate chamber ( 17 ) is arranged. Headbox ( 1 ) according to one of the preceding claims, characterized in that the headbox ( 1 ) is a multi-layer casserole.