FI84086B - Method and arrangement to develop turbulence and diffusion in a headbox of a paper machine - Google Patents

Description

84086 1 Method and apparatus for generating turbulence and diffusion in a paper machine headbox Förfarande och anordning för att utveckla turbulens och diffusion i inloppsladan av en pappersmaskin 5

The invention relates to a method for providing turbulence and diffusion for a pulp suspension flow in a paper machine headbox lip channel, which method comprises applying a flow controller composed of a plurality of flow controllers for generating turbulence and diffusion in the pulp suspension flow.

In addition, there is provided a flow controller for a pulp suspension flow channel in a paper machine headbox, which provides turbulence and diffusion for the pulp suspension flow past the flow-15 controller.

The invention further relates to a paper machine headbox turbulence generator located on the inlet side of the paper machine headbox lip passage 20, the turbulence generator comprising a flow control.

It is known that the fibers of the pulp suspension flowing in the headbox tend to be profitably oriented in the direction of flow, i.e. in the machine direction, as if the logs were in the flow. The predominance of the machine direction orientation 25 is further enhanced by the speed difference between the pulp jet and the wire, which often has to be used for many reasons. Therefore, with the previously known machines, the tensile strength ratio MD / CD tends to become far too high and the profile of the tensile strength ratio in the transverse direction is uneven, which is a very big disadvantage, especially with printing papers. This disadvantage has become more pronounced in modern printing methods, such as laser printing, in which one surface of the paper is suddenly heated. Particularly high excessively high tensile strength ratios MD / CD appear with kit formers.

35 The headbox of a paper machine uses various turbulence generators and diffusers to provide a level of diffusion and turbulence suitable for lip flow and lip jet, which is important for good paper formation and a sufficiently low tensile strength CD ratio. It is known that headboxes most commonly use velocity differences due to friction in the flow directions, which transversely affect the mass flow velocity, consistency and turbulence intensity profiles, as well as the fiber orientation profiles, to produce turbulence. It is known that a series of vortex flows occurs next to said walls so that the vector defining the eddies is perpendicular to the direction of flow (Figures 3B and 3C). The disadvantage of said previously known j0 turbulence field is that its vortex shape changes (Fig. 3D) as the mass suspension flow accelerates in the shrinking lip channel. This deformation of the vortices takes place according to the accompanying figure 3D so that the vortices are elongated in the accelerating mass flow of the lip channel.

15

In the lip channel of the headbox of a paper machine, individual vortices in the pulp suspension are difficult to detect because the flow is completely turbulent.

However, it is obvious that the direction of the plane of vortices is important for the orientation distributions of the fibers of the pulp suspension. The vortices of the pulp suspension provided by the previously sensed planar walls, the vector of which is perpendicular to the main direction of flow (Figs. 3B and 3C), cannot be said to affect the fiber orientation.

When designing a headbox turbulence generator, there has been a fundamental contradiction between providing a sufficient turbulence level and generating speed and consistency profile errors, as raising the turbulence level generally increases said profile errors when using a previously known turbulence generator.

30 Another problem with the known headboxes is that the level of turbulence in the lip channel of the headbox has time to decrease before the lip opening and the discharge of the lip jet, so that too high a tensile strength ratio MD / CD and other problems due to low turbulence begin to appear in the finished paper.

The basic problem with the previously known headboxes is that they do not work optimally in all conditions in terms of stability, uniformity of different profiles and suitable turbulence vortex size and turbulence intensity.

With respect to the state of the art most closely related to the present invention, we refer to U.S. Patent 4,812,208 and FI Application 883375, as well as Applicant's Non-Public FI Application 893997 (filed August 25, 1989).

It is an object of the present invention to provide a new method and apparatus which can efficiently provide both turbulence and diffusion into a headbox flow without too large aforementioned profile errors.

The object of the invention is to provide a method and a device with which the main level or levels of vortices 15 produced for the headbox flow of the pulp suspension are such that the generated turbulence keeps the MD / CD tensile strength ratio sufficiently low also with planar wire sections and hybrid formers.

It is a particular object of the invention to provide a method and a device with which all vertical walls can be eliminated from the discharge end of a turbulence generator, whereby substantially better flow profiles in the transverse direction can be realized.

It is a particular object of the invention to provide a method and apparatus in which the flow guides can be dimensioned in the transverse direction to suit their critical dimensions so that the just-desired transverse profile of the turbulence plane can be realized.

It is a particular object of the invention to provide a method and device in which different flow controllers can be easily interchanged so that it is possible to adjust the level of turbulence intensity, e.g. when changing the machine speed and / or changing the quality to be manufactured. In connection with the above, the object of the invention is to provide a method and flow controllers applying it, the sizing of which makes it possible to implement several different flow controllers from which very different flow controllers can be assembled, with which the different flow profiles of 4,84086 headboxes can be controlled quite precisely.

In order to achieve the above-mentioned and later-achieved objects, the method of the invention is mainly characterized in that in the method, The directions of the -10 den vortex vectors are substantially parallel to the main direction of the vortex mass suspension flow.

The flow guide according to the invention is mainly characterized in that the flow guide has substantially vertically flowing, downwardly shrinking side surfaces and flow-widening opposite second side surfaces connecting said opposite side surfaces, which join on the outlet side of the flow guide.

The method and flow controllers according to the invention provide helical vortices whose direction of the flow vector is substantially parallel to the mass suspension flow. Such a vortex is stable and effectively reduces the tensile strength ratio MD / CD and its vortex size can be dimensioned to suit.

25

The delta bodies according to the invention can be made up of very different flow guides and, in addition, when the flow guides are arranged to be replaced, e.g. or when changing the paper quality or machine speed, all or some of the flow guides can be replaced so that the headbox can be adjusted exactly to the new operating conditions.

The invention will now be described in detail with reference to a number of different application examples of the invention shown in the figures of the accompanying drawing, to the details of which the invention is in no way limited.

5,84086 1 Figure 1 shows a schematic machine direction vertical cross-section of a paper machine headbox, in which the method and apparatus according to the invention are preferably applicable.

g Fig. 2 shows an axonometric view of, for example, the flow guide located at the discharge end of the turbulence generator according to Fig. 1.

Figure 3A schematically shows the flow field and the generation of helical vortices in connection with the flow controllers according to the invention.

10

Figure 3B shows the principle of vortex generation in previously known headboxes.

Fig. 3C shows the previously known orientation of the vortex vector of Fig. 3B.

Figure 3D shows the elongation of vortices generated by previously known devices in the accelerating mass flow of the lip channel.

Fig. 3E shows, in a manner similar to Fig. 3D, the deformation of the vortices provided according to the invention as the lip channel narrows and the mass flow accelerates.

Figure 4 shows in the x-z coordinate system the dimensions essential for the dimensioning of the guide piece 25 according to the invention.

Fig. 5 shows graphically the cross-sectional area A (x) of a guide body according to the invention in the flow direction x.

Figure 6 shows the outlet end of the headbox turbulence piping to which the flow guide according to the invention can be attached.

Figure 7 shows a top view of a typical flow controller according to the invention.

Figure 8 shows the same as Figure 7 seen from the side.

35 6 84086 1 Figure 9A shows a side view of a flow controller according to the invention.

Fig. 9B shows a front view of the flow guide 5 according to Figs. 7 and 8, for example located in the central region of the turbulence generator.

Fig. 9C is a front view of the flow guide of Fig. 9A.

Fig. 10A is a side view of a flow guide for positioning the flow guide, in particular in the bottom and top rows.

Fig. 10B is the same as Fig. 10A seen from the front.

Fig. 11A shows a top view of an alternative extended flow guide for fitting to the bottom and bottom rows of the guide, in particular.

Fig. 11B shows the same as Fig. 11A seen from the side.

Fig. 11C is the same as Figs. 11A and 11B seen from the front (from the direction K indicated in Figs. 1 and 2).

Figures 12A, 12B, 12C, 12D, 12E and 12F show some flow guides according to the invention with different modifications at the leading edge.

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Fig. 12G shows a substantially different modification of the flow guide according to the invention, consisting of a vertical triangular body and a plate-like delta wing body mounted thereon.

Fig. 13A is a front view of a flow guide having a rectangular triangular shank portion on the inlet side of the flow.

Fig. 13B shows the same as Fig. 13A seen from the side.

Fig. 13C shows, in a manner similar to Fig. 13B, an alternative flow guide design with Fig. 13B.

Fig. 14A shows a flow control according to the invention seen from the outlet side.

Fig. 14B shows the top rows of the flow controller of Fig. 14A seen from above.

Fig. 15A is a plan view of an oscillating flow guide with an elongate arm.

Fig. 15B shows the same as Fig. 15A seen from the side.

Fig. 15C shows the same as Figs. I5A and 15B seen from the front.

Fig. 16 schematically shows the structure of the upper and lower wall of the lip channel using a turbulent step-increasing step.

Fig. 17 shows the same as Fig. 16 in an axonometric view.

Figures 18A and 18B illustrate groove mounting options for the top-20 bottom row flow guides of Figures 16 and 17.

Figure 19A shows a schematic side view of a flow software according to the invention.

Fig. 19B is the same as Fig. 19A seen from the front.

Fig. 20A is a schematic side view of a flow guide with unidirectionally tapered guide members.

Fig. 20B is the same as Fig. 20A seen from the front.

Figure 2IA is a side view of a flow control with tapered guide pieces with an even number of rows.

Fig. 21B shows the same as Fig. 21A seen from the front.

35 8 84086 1 Figure 1 schematically shows a substantially known headbox in which the flow control device 300 according to the invention can be advantageously applied. Through the lip gap 22 at the outlet end of the headbox lip channel 21, adjusted by the tip strip 23, a mass-j suspension jet J is fed to the forming wire 10 passing over the breast roll 11.

In the flow direction F of the pulp suspension, the headbox first comprises a manifold 12, then a manifold 13 which opens into the equalization chamber 14. The equalization chamber 14 communicates via the upper duct 15 with the air space V of the tank 16, which dampens pressure fluctuations. Following the equalization chamber 14 follows a turbulence generator comprising a perforated plate 17 having a plurality of parallel and e.g. three overlapping rows of flow holes 18. Each flow hole 18 coaxially joins its turbulence tube 19, which begins in a circular cross-section and ends rectangularly as shown in Figure 6. A flow guide 300 according to the invention is arranged in the discharge level 20 of the turbulence piping 17. After the guide 300, a wedge-shaped tapered lip channel 21 follows, which terminates at the tip strip 23 in the lip opening 22.

The lip channel 21 of the headbox shown in Fig. 1 is bounded above the upper lip wall 24 and below the lower lip wall 25. The headbox rests on the base structures 26. Figure 6 shows the plane 20 of the outlet end 19 of the turbulence piping, to which the flow guide 300 according to the invention is fitted. The discharge ends of the turbulence piping have a rectangular cross-section. The leaving ends of the tubes 19 are delimited by spacers 27 and 25 horizontal walls 29. According to Fig. 6, the overlapping arrangement of the tubes 19 is overlapped.

It should be emphasized in this connection that the flow guide 300 according to the invention functions in part as a turbulence generator and in addition as a diffuser 30, which smooths out, for example, the vanity caused by the vertical walls of the piping 19 and various profile errors.

Figure 2 shows a preferred flow controller 300 according to the invention, comprising three overlapping rows of flow controllers 30.

35 Each guide row has a plurality of guide pieces 30 in the same horizontal plane, which are in adjacent rows laterally offset from each other.

s, 84086 1 Figure 6 shows the discharge level 20 of the turbulence piping 19, to which the flow guide 300 according to the invention can be attached.

According to Fig. 6, the discharge plane 20 of the turbulence piping 19 has intermediate pieces 27 with holes 28 to which the fastening part 31 of the pieces 30 can be fastened. In this case, the guide 300 shown in Fig. 2 is formed, which forms a transition zone between the turbulence piping 19 and the free end of the lip channel 21, which increases the effective turbulence and diffusion into the pulp suspension.

1q Figure 4 illustrates the sizing of the body 300 30. The pieces 30 are wedge-like constricted in the vertical plane, comprising planar surfaces 34a and 34b which converge at their exit end at the tip edge 33. Seen from above, the guide pieces 30 expand transversely in the flow direction v of the pulp suspension so that the horizontal dimensions are shown in Figure 5. cross-sectional area A (x). Area A (x) at the discharge plane 20 of the turbulence piping 19 at A (0) = D x B. Thereafter, proceeding in the flow direction x, the area of the bodies 30 expands to x where it is at most A. The point x can be calculated o max o 20 as follows: (A - 2B) C (1)

Xo "2 (A - B)

The cross-sectional area A (x) can be calculated from the following formulas: A (x) = (Β + γχ) (D - £ x) (2) n, A-2B A-B 2.

30 - D <B + - x - -Γ x) (3)

The delta bodies 30 according to the invention are characterized in that their cross-sectional area A (x) in the flow direction x first expands at xq to the area A ^ y and this expansion area has a corresponding constriction area in the mass flow. According to Fig. 5, after point xq, the cross-sectional area A (x) of the delta pieces 30 decreases, in which area up to point C there is an area of expansion of the flow cross-section at the beginning of the lip channel 21.

In the following, the flow technical operation of the guide pieces 30 of the flow controller 300 according to the invention will be described mainly with reference to Fig. 3A.

Figure 3A illustrates the flow fields generated by the delta body 30 according to the invention. The flow field Fg 10 associated with the tapered vertical side surfaces 35a and 35b of the delta body 30 (in the flow direction F) is dispersed due to the constriction of the flow cross section and the flow spreads over the delta body edge S to the expanding surfaces 34a and 34b of the delta body 30. In this case, the helical vortices H illustrated in Fig. 3A are generated, the directions of the vortic vectors of which are substantially parallel to the direction r1 of the mass suspension flow. Flows refracting over the edges S are indicated by arrows Fg. Said currents induce the above-mentioned gentle vortices H.

Figure 3D illustrates the mode of deformation of vortices generated in previously known turbulence generators, the vectors t of which are perpendicular to the flow direction, in the accelerating mass suspension flow of the lip channel 21. As shown in Figure 3D, the vortices become elliptical in the direction of the mass suspension flow as it accelerates, resulting in certain disadvantages. In the method according to the invention, the shape of the helical vortices generated, the vortex vectors t of which are substantially parallel to the direction F of the pulp suspension flow, changes according to Fig. 3E so that the gentle vortices Η ^, Η ^, Η ^ as a result, the turbulence size of the mass suspension-30 flow remains correct even in the accelerating flow of the lip channel 21.

The flow fields generated in connection with the delta bodies 30 have been extensively studied in connection with other applications, such as delta airplanes, in part of which reference is made to the theoretical background of our invention in NASA Technical Note, TN D-3767, E.C. Polhamus "A Consept of the Vortex Lift of Sharp-Edge Delta Wings Based on a Leading-Edge-Suction Analogy," 84086 11 1 Washington D.C. December 1966. In addition, the function of delta bodies as diffusers in gas flow fields has been studied. For these studies, reference is made to the journal article in the Journal of Fluids Engineering, June 1989, Vol. 111 p. 111-117 Goenga, Panton, Bogard "Studies of Flow 5 Patterns in a Diffuser Designed to Generate Longitudinal Vortices". The theoretical background of the invention is referred to in the two publications mentioned above.

In addition, reference may be made to Article A.M. Skow, A. Titiriga: "A survey of Analytical and experimental techniques to predict 10 aircraft dynamic characteristics at high Angles of attack." NATO AGARD-CP 235, No. 19, 1978, which describes water tests performed with deltaives and the effect of sizing on flow detachment and stability.

j5 Figures 3B and 3C illustrate vortices T generated in connection with the walls W used in previously known turbo-lens generators. The vortex vectors t of these vortices T are perpendicular to the direction of the mass vector v of the pulp suspension flow according to Figures 3B and 3C. In this respect, a very essential feature of the invention is that the vortex vectors v1, vT of the helical vortices H1, H1, are substantially parallel to the flow vector v of the flow in the lip channel 21, with the result that said helical vortices efficiently orient the pulp fibers in the transverse direction. and provide a level of turbulence such that a sufficiently large transverse orientation of the fibers relative to the machine direction is provided to reduce the tensile strength ratio. It should be emphasized that Figures 3A, 3B and 3C are very schematic and are intended only to illustrate the flow engineering principles and differences underlying the present invention compared to previously known turbulence generators.

The properties of the delta bodies 30 include that their cross-sectional area in the direction of flow initially increases (x <xq), accelerating the flow and forcing it to rotate over the angular edge S of the bodies 30, whereby said helical vortices are generated. Hi Ikaal vortices are known to be stable, flow-retaining structures. At the same time, the guide 300 formed of the delta bodies 30 is a powerful diffusion booster and produces more properly sized turbulence of the correct size. The software 300 eliminates all vertical walls from the trailing end of the turbulence generator, so that the profile errors caused by these walls do not occur or at least are attenuated. In addition, by means of friction, the surface area of the 5 turbulence-generating surface can be increased.

Since the Helium caliber from the vortices provided by the delta bodies 30, 30 'of the invention is relatively stable, a sufficient level of turbulence is maintained in the pulp seal discharged from the lip opening and until the fiber network "solidifies" on the wire 10. In this way, good formation and a sufficiently low MD / CD tensile strength ratio are obtained.

Figures 7 and 8 show a top and side view of the basic structure of a preferred delta body 30 according to the invention. The delta 30 is * 15 symmetrical with respect to its central vertical and horizontal planes. The expansion angles a of the vertical sides 35a and 35b in the flow direction are generally in the range a = 4 ° ... 40 ° and the corresponding convergence angles b of the horizontal sides 34a and 34b are in the range b = 4 ° ... 30 °. 30 tracks the input side of the hoist 32 is dimensioned spacers of FIG sizing June 25, so that 20 square pipes 19 extend continuously tracks 30 of the box.

The fastening arms 31 fit into the holes 28 of the pieces 27 with a sufficiently tight fit.

The following is a limiting example of the 10 different dimensions A, B, C and D of the delta body, their widest ranges, and the most suitable, most commonly used ranges.

30 35

TABLE 1

i3 84086

WIDER The most suitable ranges ranges 5 _________ A 10 ... 100 am 20 ... 35 mm B 1 ... 30 mm 3 ... 12 mm 10 _________ C 20 ... 600 mm 40 ... 120 mm D 5. ..40 mm 20 ... 30 mm 15 angles OC 4 ° ... 40 ° 4 ° ... 12 ° / b 4 ° ... 40 ° 4 ° ... 15 ° 20

Fig. 9A shows a delta body 30 for use in particular in the top and bottom rows of the flow guide 300, with the plane side 34c of the body 30 facing the top or bottom wall 24,25 of the lip channel of the turbulence generator. On the opposite side of the downstream side 34c 25 is a planar side 34d, the angle b of which in the flow direction is in the range b = 4 ° ... 40 °. Fig. 9B shows, for example, the guide piece 30 according to Figs. 7 and 8 seen from the front, and Fig. 9C shows the delta piece 30 of Fig. 9A seen from the front.

Figures 10A and 10B show a delta 30 which is also suitable for use in the top and bottom rows of the guide 300. These pieces 30 have a flat side 34e which is parallel to the flow and a trailing edge 33 'transverse to the flow.

Figures 11A, 11B and 11C show extended flow guides 30 'corresponding to Figures 9A and 9C, for use in particular in the top and bottom rows of the guide 300 (Figures 19A and 19B). Fig. 11A shows a top view of the guide 30 'from. Λ n ~' 14 «'fUÖÖ 1. The dimensioning of the delta 30 'shown in Figures 11A.11B and 11C is most suitably as follows: C = 40 ... 120 mm, A = 20 ... 35 mm, B = 3 ... 12 mm and angle b 4 ° ... 15 °.

Referring now to Figures 12A-12G, some preferred delta bodies 30 having a modification substantially at the trailing edge 33 will be described. The delta bodies 30 of Figures 12A-12F are substantially in accordance with the basic version of the invention shown in Figures 7.8 and 9C. The variations of Figures 12A-F are designed to increase turbulence, especially in the area of the delta piece attachment point 32 where there is no inclined edge S to generate helical turbulence. Fig. 12A has a circular notch 33a at the trailing edge of the guide, Fig. 12B has a planar notch 33b extending over the entire horizontal width A of the body 30, and Fig. 12C has a V-notch 33c having a smaller dimension. In Fig. 12D there is a plane 33d at the trailing edge, the vertical dimension d of which is generally in the range d = 1 ... 4 mm. The notches 33a, 33b, 33c and the planar surface 33d are intended to promote the turbulence generated by the guide edge 30 for the mass suspension flow. Fig. 12E shows oblique triangular planar surfaces 33e at the trailing edge 33 of the delta body 30 and Fig. 12F has a spear-shaped guide body 331 which also promotes the turbulence of the trailing edge 33.

Fig. 12G shows a particular embodiment of the invention in which the body of the delta body 30A is formed by a triangular portion having parallel planar side surfaces 35g which are triangular in shape 25 and narrow side surfaces 34h, one of which is joined by a plate-like delta wing 34g having a sharp trailing edge 33g.

Fig. 13A is a top view of a delta body 30 according to the invention to which is attached an arm portion 36 having a rectangular cross-section 30 and a delta body as shown in Figs. 7 and 8 as an extension thereof. Fig. 13B shows the same as Fig. 13A seen from the side. The length of the arm part 36 is generally => 100 ... 400 mm, whereby dimension A

is class A = 20 ... 45 mm and dimension R is class B = 5 ... 20 mm.

Fig. 13C shows a modification of the guide according to Figs. 13A and 13B, which is particularly suitable for use in the top and bottom rows of the flow guide 300 1 so that the flat side 34C abuts the top or bottom of the lip channel. The planar sides 35c are triangular in Fig. 13C.

is 04086

Figures 14A and 14B show the use of the guides 30 of Figures 13A and 13B to form a guide 300 in connection with a turbulence piping or perforated plate 41 having circular cross-sectional flow openings 19a. From said openings 18a, the mass flows discharge after the expansion stage in the plane 20 into the spaces between the planar walls of the arm parts 36 of the delta bodies 30, followed by the following delta bodies 30 according to the invention.

Figures 15A, 15B and 15C show a version of the invention in which the delta bodies 30 are at the end of a relatively long arm 37. The arms 37 are attached, for example, to the plane of the discharge end of the turbulence generator or to a corresponding perforated plate. The arms 27 are so long that they can vibrate (arrows T) under the influence of the flow and caused by turbulence, especially in the pedal direction and to some extent also in the vertical direction. Torsional oscillations of the arms and the guides 30 at their ends are also possible, as illustrated by the arrows T shown in Fig. 15C. Said oscillation 20 generates further turbulence and vortex vanes in the pulp suspension flow.

Fig. 16 schematically shows the lower or upper wall of the headbox lip channel 21 with a step 38. The height of the step 38 is H = 0 ... 10 mm and the distance of the step from the trailing edge 33 of the guide pieces 30 is 25 = 0 ... 200 mm. The step 38 can be provided, for example, by a separate plate piece, the edge of which forms the step 38. Fig. 17 illustrates the same as Fig. 16 in an axonometric view.

Figures 18A and 18B illustrate the attachment of the delta pieces 30 to the lip channel wall 25. As shown in Figure 18A, the bottom side groove 39a of the delta pieces 30 and the corresponding protrusion 40a of the wall 25 are used in this attachment. As shown in Fig. 18B, the underside 37c of the delta pieces 30 has a protruding portion 39b which fits snugly into the corresponding groove 40b of the wall 25. The delta pieces 30 can be attached to the wall 25 or the like-35 but also by gluing or the groove-protrusion attachment is ensured by gluing.

Figures 19A and 19B illustrate a guide 300, 16 84086 1 of the invention in which three rows of delta 30 are used in the middle and edge pieces 30 'in connection with the upper leg 24 and lower leg 25 of the lip channel 21 so that the angles α between the side surfaces 34a and 34d are equal to the flow direction F. The magnitude of said angle α is preferably 5 in the range a = 4 ° ... 15 °. Figure 19B shows the lateral arrangement of the delta pieces 30,30 '. The delta pieces 30,30 'are laterally offset so that the pieces in each row are in the middle of the pieces in the row of pieces above and below.

Figures 20A and 20B show an embodiment of the invention in which the software 300 consists of delta pieces 30 'tapering on one side, all pieces 30' of equal length. The delta bodies 30 'are arranged so that their downstream sides 34c are alternately above and below.

15

Figures 2JA and 21B show, in a manner similar to Figures 20A and 20B, a modification of the invention using unidirectionally tapered delta 30 'with planar sides 34c always on the same side and in the top and bottom rows against the walls 24 and 25 of the lip duct 21, and with an even number of spacers .

As shown in Figures 19A, 19B; 20A, 20B and 21A, 21B in part, very different guides 300 can be assembled from the delta pieces according to the invention. the figures show structures in which the delta-25 pieces in the edge rows are different from those in the middle rows, but even in the middle rows the delta pieces 30 may be different from each other in different rows. In addition, the polygonal profiles can also be adjusted and controlled so that in the transverse direction the different delta pieces 30 are dimensioned differently so that the different transverse profiles are desired and generally uniform.

Finally, it should be emphasized that the method and flow software 300 according to the invention can be applied to a wide variety of headboxes, and the invention is by no means limited to e.g. a headbox as shown in Fig. 1. The flow control system according to the invention can be used alone as a turbulence generator or in combination with e.g. a perforated plate 41 or a turbulence piping 19. The length of the delta pieces 30 can also vary within quite wide limits, even so that the delta pieces extend over a large or even most of the length of the lip channel 21 in the flow direction F. Also delta pieces 30 according to the invention placed at the end of an elongate shaft that the delta bodies 30 can vibrate can be applied within the scope of the invention. Several other variations other than those described above are possible.

The following claims set forth within the scope of the inventive idea, the various details of the invention may vary and differ from those set forth above by way of example only.

15 20 25 30 35

Claims (16)

A method for providing turbulence and diffusion to a pulp suspension flow of a paper machine headbox lip channel (21), the method comprising applying a flow controller (300) comprising a plurality of flow controllers (30) for generating turbulence and diffusion in the pulp suspension flow; 30) at the edge edges (S) between the substantially planar surfaces (34a, 34b and 35a, 35b) and the constriction (x <xn) and expansion (x> x0) of the flow cross-sections formed in connection with the flow guides (30) in the flow direction (x) provide the edges (S) overflowing flows (Fc) into helical (corkscrew) vortices (H), the directions of the vortex vectors (vH) of which are substantially parallel to the main direction (F) of the turbulent mass suspension flow. 15 Method according to Claim 1, characterized in that a flow guide (300) is used, the flow guides of which consist of delta bodies (30; 30 ', 30A) whose rectangular cross-sections are perpendicular to the flow direction (F) of the pulp suspension. and that the delta bodies (30) are dimensioned so that their cross-sectional area (A (x)) from the outlet side initially expands in the flow direction to a certain point (xc), after which the area (A (x)) decreases (Fig. 5). Method according to Claim 1 or 2, characterized in that delta bodies (30) with triangular, flow-constricted vertical sides (35a, 35b) and trapezoidal horizontal sides (34a, 34b) which are used in the flow direction are used as flow guides. expand (A> B). 30 Method according to one of Claims 1 to 3, characterized in that the method is applied on the discharge side of the headbox turbulence piping (19) and / or perforated plate (17; 41), the flow guide (300) is located on the inlet side of the headbox lip channel (21) and the flow guide (300) such turbulence is provided that a level of turbulence in the lip jet (J) 19 84086 discharged through the lip opening (23) of the discharge end of the lip channel (21) achieves a sufficiently low tensile strength ratio (MD / CD) of the paper. Method according to one of Claims 1 to 4, characterized in that the method uses a flow guide strip (300), the delta pieces (30) of which are attached to the end of an elongate (L) shaft (37) of such material and length that the flow guide the delta bodies (30) oscillate (T) induced by mass flow (Figures 15A.15B and 15C). 10 A flow guide (30; 30 ', 30A) for a pulp suspension flow channel of a paper machine headbox, which can provide turbulence and diffusion for the pulp suspension flow past the flow guide, characterized in that the flow guide (30; 30'; 30A) has substantially 15 vertical ) the tapered side surfaces (35a, 35b, 35c, 35g) and the opposing side surfaces are connected by oppositely flowing opposite second side surfaces (34a, 34b) which join on the outlet side of the flow guide to the edge (33) or the narrow outlet surface (33a-33g). Flow guide according to Claim 6, characterized in that the side surfaces are essentially planar surfaces (35a, 35b, 35c, 35g; 34a, 34b), the boundary section of the flow guide (30; 30 '; 30A) in a plane perpendicular to the flow being rectangular, and 25 that the cross-sectional area (A (x)) from the flow guide inlet side (32) initially increases to a certain point (xQ), after which the area (A (x)) decreases to the discharge edge (33) or surface (Fig. 5 ). Flow guide according to Claim 6 or 7, characterized in that the flow guide (30; 30 '; 30A) has a rectangular inlet side (32) whose height (D) is substantially greater than its transverse width (B), which the width (B) is substantially less than the width (A) of the outlet end of the flow guide (30). Flow guide according to Claims 6 to 8, characterized in that the flow guide (30A) consists of a substantially vertically tapered triangular guide body (35g) with a plate-like delta body (34g) connected to one edge side and having a leading edge width ( B) is substantially smaller than the width (A) of the trailing edge (33g) (Fig. 12G). 10. any one of claims 6-9 flow controller according to tun characterized in that the flow control is from the flow of the main plane parallel to the horizontal plane surface (34c) and facing flow direction-in relation to a small angle (b) a planar surface (34d), which surfaces converge the downstream rim ( 33) or on the surface (Figs. 9A, 11A, 11B). 10 Flow guide according to one of Claims 6 to 10, characterized in that the inlet side of the flow guide has a fastening part, preferably a fastening pin or rod (31), which fits into a corresponding fastening hole (28). 15 Flow guide according to one of Claims 6 to 11, characterized in that the inlet side of the flow guide has an elongate stem (36; 37), which stem is preferably steplessly connected to the planar delta (30) of the flow guide (30) and that the stem length (L ) is in the range L - 100-400 mm. A paper machine headbox turbulence generator disposed in a paper machine headbox flow channel, preferably on the inlet side of a lip channel (21), the turbulence generator comprising a flow control system (300), characterized in that the flow control system (300) is composed of a plurality of parallel (30; 30 '; 30A). Turbulence generator according to claim 13, characterized in that the flow guide (300) consists of two or more overlapping cross-rows of flow controllers (30; 30, 30A), each row being adjacent to each other in a large number, and that the flow guides of the overlapping rows are offset . Turbulence generator according to one of Claims 13 or 14, characterized in that flow guides (30 ') with a lower and / or upper wall (24) of the lip channel (21) are used in the lower and / or upper rows of the flow guide (300). , 25). Turbulence generator according to one of Claims 13 to 15, characterized in that the inlet side of the flow guides (30) has a fastening part (31), preferably a circular cross-section loss part, which can be fitted in the turbulence generator turbulence piping (19) or corresponding perforated plate mounting hole (28). 10 22 84086