FI92228C - Method and device for headbox adjustment - Google Patents

Description

92228

Method and apparatus in headbox assembly Forfarande and anordning vid regiering av inloppslådan 5

The invention relates to a method and an apparatus for controlling the headbox of a paper machine / board machine, by means of which the method and apparatus according to the invention can reliably influence the basis weight profile of paper from paper / board web width and preferably also paper / board web fiber orientation profile from paper / board web.

10

As is previously known, the lip flow of the headbox pulp suspension must be constant in the transverse direction of the paper / board machine. The transverse flow that creates the distortion of the fiber orientation is due to the quality factors of the paper to be produced, such as the anisotropy of strength and elongation. The level and variation of the anisotropy in the transverse direction also affects the printing properties of the paper. A particularly significant requirement is that the principal axes of the orientation distribution of the paper fiber network coincide with the directions of the major axis of the paper and that the orientation be symmetrical with respect to these axes.

20 At the edges of the headbox mass flow channel, less mass flows. This edge effect causes a very strong linear skew in the profile. Profile defects in the headbox turbulence generator generally cause a non-linear skew within the edge regions of the flow channels of the profile.

25 The unevenness of the square mass profile caused by the drying shrinkage of the paper is compensated by bombarding the lip opening so that the lip opening is thicker in the middle of the pulp jet. When the paper web is dried, it shrinks less from the center of the web than from the edge areas, with the shrinkage generally being about 4% in the middle and about 5-6% in the edge area. Said shrinkage profile causes a change in the corresponding basis weight cross-sectional profile of the web so that due to the shrinkage the dry square weight profile of the web transverse to the basis weight of the press changes during drying so that both edge regions of the web have a slightly larger basis weight than 92228. As is previously known, said square mass profile is adjusted by means of a tip strip so that the tip strip of the headbox is kept open from the central area rather than from the edge areas. By means of said arrangement, the pulp suspension is forced to move towards the central region of the web. This fact continues to affect the orientation of the fiber orientation. The directional distribution of the fiber network, i.e. the main axes, should coincide with the directions of the main axis of the paper and the orientation should be symmetrical with respect to these axes. In said carcass balance, the change of orientation is influenced as the mass suspension flow obtains lateral components.

10 Adjusting the lip of the headbox also causes a change in the transverse flows of the pulp jet, although the purpose of the pulp is to affect only the square mass profile, i.e. the thickness profile of the pulp suspension layer to be fed. The transverse flows thus have a direct relation to the distribution of the fiber orientation.

15 Equipment solutions for adjusting the fiber orientation and equipment solutions for adjusting the track four-weight profile are known separately from the prior art. However, in the solution according to the prior art, adjusting the basis weight by means of a tip strip also inevitably affects the fiber orientation of the web.

A method is known in the art for controlling the skew of the fiber orientation of a paper web in the headbox of a paper machine. In the method, the fluid flows are directed to the edge cells at the headbox turbulence generator and the magnitude and mutual ratio of said flows are influenced to affect the transverse flows of the pulp suspension and thus to adjust the skew of the fiber orientation. The flows introduced into the edge soles generate a transverse flow rate that compensates for the distortion of the fiber orientation.

Applicant's prior F1 patent application 884408 again discloses a method for controlling the distribution of the fiber orientation of a paper web in the headbox of a paper machine in the transverse direction of the machine 30, which method provides a transverse velocity component of a lip jet by directing a turbulence generator.

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With the above-mentioned known methods of controlling the fiber orientation of the paper web, generally only linear skew profiles can be controlled. The known methods are suitable for controlling the fiber orientation, but when used they generally leave even a large nonlinear residual error with respect to the uniform distribution of the orientation. The known methods are well suited to the basic direction of orientation skew. However, with the known methods it is not possible to control the individual errors that can occur in the orientation in the middle region of the track and which are caused, for example, by the errors of the turbulence generator piping.

A number of methods for producing a tip strip are also known, in which measuring the basis weight profile 10 the position of the tuft strip in the headbox of a paper machine is changed and the thickness of the pulp suspension discharged onto the wire and thus the basis weight of the paper web is influenced. However, said flow causes orientation errors as described above, because the flow restricts the flow on the other hand and thus causes lateral velocity components in the flow.

15

FI patent application No. 912230 is known from the prior art, in which a headbox is divided along its width into partitions by a partition and in which the solution in a single compartment has at least one input line for conducting a partial current. In addition, in the solution, a stirrer is connected in front of the single inlet line, with which the mass suspension ratio can be adjusted. However, the solution has not been able to show how the mixing ratio can be reliably adjusted without changing the flow rate. No detailed solution for implementing the såådo has been presented.

Our application presents a detailed method and apparatus solution by means of which the consistency of the pulp suspension can be adjusted without causing a change in the flow rate. RÅÅN. Also shown is a solution in which the pressure level of the total flow and thus the flow rate and flow rate can be adjusted while the mixing ratio remains at its controlled constant value.

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The goal of the consistency yield of the basis weight is to remove the coupling of the cross-sectional profile and the fiber orientation profile. When adjusting the cross-sectional profile of the basis weight by profiling the consistency, for example, when using 0-water, the maximum dilution water volume is 20 1 / m / s. In order not to cause transverse flows in this volume of water and to eliminate the target of consistency-5, the dilution water volume must be compensated so that the flow rate from the turbulence generator in the cross-machine direction is constant. The mixed / thickened flow rate should be kept constant. In the solution according to the invention, an equal overflow flow is implemented with the consistency flow.

In the structure according to the invention, the intermediate chamber divided into zones acts as a mixing chamber. An overflow is arranged in each zone, bounded from above by a common airspace for all overflows. The number and width of the zones correspond to the desired yield resolution.

Process 15 In the invention according to the perålaatikon såådosså is pååasiallisesti TU-characteristic pattern of and working secondary pulp suspension flow konsentraatiosåådosså compound-tåån two osavirtausta by bringing the pulp suspension lisåvirtaus, and and working the flow of the mixture ratio såådetåån sååtåmållå said lisåvirtausta våhentåmållå or lisååmållå said lisåvirtauksen throttling connect-Neen with valves and and working menetelmåsså 20 lisåvirtauksen submerged after the junction of the pulp suspension flow, a part of the combined flow is overflowed and the rest of the flow is led to the headbox pulp suspension, in which case, for example, as the total flow Q1 + Q3 increases, the Qj flow increases in excess, i.e. the flow Q2 exits the overflow and the flow Q4

25

In the invention according to the device perålaatikon såådosså is pååasiallisesti characterized and working lead to the pulp suspension flow is formed from at least two partial flows, wherein the laitejåijestely kåsittaå different width positions perålaatikon lisåvirtausputket, through which a lisåvirtaus stock suspension and and working laitejåijestely kåsittaå 30 of the election to estetåån the combined flow in mixing perålaatikon the width of the mouth-direction, whereby the device solution of comprises, in the width direction of the headbox, the zones, wherein li 92228 5 there is an overflow in each zone, whereby the overflow is used to keep the flow of the combined mass flow Qj + Qj leaving the zone in each zone equal to the flow rate and thus the flow Q4

5

The invention will now be described with reference to some preferred embodiments of the invention shown in the figures of the accompanying drawings, to which, however, the invention is not intended to be exclusively limited.

Fig. 1A schematically shows a headbox of a paper machine / board machine according to the invention, into which 0-water is introduced along its own channel to adjust the mixing ratio at a certain headbox width position and in which the intermediate chamber comprises overflow in a flow rate.

Fig. 1B is a section I-I of Fig. 1A.

Fig. 1C is an axonometric fragmentary view of the widthwise block structure of the paper machine / board machine shown in Figs. 1A and 1B.

Fig. 2A is a schematic cross-sectional view of a paper machine headbox comprising separate zones formed at different widths of a paper machine / board machine headbox, i.e., blocks formed by pipe connections.

Figure 2B shows a section II-II of Figure 2A.

25

Figure 2C shows a section III-III of Figure 2A.

Figure 3A shows an embodiment of the invention in which the flow rate Q4 is controlled by valves arranged in the turbulence tubes of the top row of the turbulence generator.

Figure 3B is a section IV-IV of Figure 3A.

30 92228 6

Fig. 1A shows a headbox of a paper machine / board machine according to the invention, comprising a pulp suspension M in the flow direction S proceeding from the manifold 10, the manifold 11, the intermediate chamber, i.e. the mixing chamber 12, the turbulence generator 13, 13a22 ... and a lip channel 14 into which the turbulence tubes 13alp1, 13a2-1 ..., 13a12,13a2 2 ... of the turbulence generator 13 open. The lip channel 14 is bounded by a fixed lower lip wall IS and an upper lip wall 16 pivoting around the joint. In describing and talking about the paper machine in the following description, it is clear that it can also be a cardboard machine and its headbox.

10

In the structure according to Fig. 1A, the intermediate chamber 12 is divided in the width direction of the headbox of the paper machine into several adjacent zones, i.e. blocks 12a1,12a2 ... 12an. Each zone 12a1,12a2 ... is associated with an additional flow channel 20a1,20a2 .... 20an, preferably an O-water channel and preferably a pipe. Each flow channel 20a1,20a2 ... provides 15 valves 21a1,21a2 ... 12an for controlling the throttling of the additional flow Qj and thus its velocity and the flow rate to the intermediate chamber 12, its respective zone 12a1,12a2,12a3 .... 12aN.

Each zone ·· is associated with the manifold 11 of the manifold 11 1 lalt 1 la2____ 20 From the manifold 10 is led the manifold 1 lat, 1 la2--. through an average concentration of mass flow into the intermediate chamber 12 of the paper machine headbox to its zones 12aj, 12a2 .... Each additional flow Qj through the channel 20a1,20a2 ... is introduced at high speed, mixing with the zones 12a1,12a2 ... of the intermediate chamber 12 12a1,12a2 ... 12an, the mixed flow Q4 25 is fed to the turbulence generator 13 to its top row turbulence tubes 13a1,13a2,13a3 ..., 13an.

Each mixing zone 12a1,12a2 ... of the mixing chamber 12 is subdivided in the width direction of the headbox so that each zone 12a1,12a2 ... is separate and has no connection to an adjacent zone. In addition, an overflow 22a1,22a2 ... 22an is arranged from each zone 12a1,12a2 .... The overflows 22alt22a2 ... have a common air space 23. Each overflow is preferably formed from a space arranged above the zones 92228 7 12aj, 12a2 ... of the intermediate chamber 12, which comprises a common air space for the overflows 22a1,22a2 ... Each overflow space is delimited by adjacent spaces in partitions 17a, 17a2 ... Thus, in the device solution according to the invention, by adjusting the heights of the overflow threshold 18a1,18a2 ..., the pressure prevailing in the intermediate chamber 12 can be adjusted. the position of the overflow threshold can be adjusted by adjusting the flow rate Q4 leaving the compartments 12a1,12a2 ... of the intermediate chamber. The overflows open into a common outlet channel 19.

10 By introducing an additional flow Qj along the channel 20a1,20a2 ... into the pulp suspension flow Q3 comprising the average concentration of the headbox, an outflow is obtained as an overflow Q2. In this case, the mixed flow Q4 entering and leaving the turbulence generator 13 is equal in volume to the flow Q3 coming from the manifold 11a, 11a. Thus, when adjusting the mixing ratio, introducing an additional flow Qj into the flow Q3 along the channel 20aj, 20a2 ... is kept constant in the flow rate Q4 going to the turbulence tube 13aj, 13a2 of the turbulence generator 13. The overflow flow Q2 is thus equal in volume to the imported additional flow Qj.

The additional flow Qj is preferably a flow containing only water, i.e. the so-called 0-water flow. The additional flow Qj can also be a mass flow, the concentration of which generally differs from the average concentration of the mass suspension in the headbox and thus from the concentration of the flow Q3.

Fig. 1B is a section I-I of Fig. 1A. As shown in the figure, each overflow zone 25, i.e. block 12aj, 12a2 ... 12an, is bounded by partition walls 17aj, 17a2 .... The overflows of the zones 12a1,12a2 ... open to a common outlet 19 on the other side of the overflow threshold 18. Each additional flow channel 20a1. .. comprises a valve 21a1,21a2 ..., whereby in the width direction of the paper machine the desired mixture ratio for the flows Q4 j, Q4 2 ... Q4 n can be set at each width point, which flow further from the turbulence-30 generator 13 from its turbulence tube 13a1,13a2 ... when coming out, acts as a flow rate at the desired width of the pulp suspension jet. The zones or blocks 92228 s 123 ^ 1232 - .. 12¾ can be formed so that the walls 173i, 1732 extend at each point of width vertically at the top of the headbox gap 3l30S3st3 to the top of the belt and further to the overflow trough where they block each block. The zones 123 ^ 1232- .. can also be formed 5 so as to comprise the bottom section D, whereby the blocks, i.e. the zones 123 ^ 1232- .. are formed in the intermediate box 12 of the headbox of the psper machine for each of its width points j3 so that the blocks are located 12 limited walls nsj.najjs pohjsoss D.

Fig. 31C is a schematic partial partial view of the width of the headbox of the psper machine shown above, in order to allow the yield of the fiber orientation of the msssssuspension to be obtained independently of each other.

Fig. 3A shows a basic view of the rear of the psper machine, in which case the embodiment of Figs. 1A-1C otherwise states that the oscillation has been carried out on the pipe connections. A valve is fitted to each overflow pipe 2203!, 22032 ... to control the amount of urine Q4, i, Q4.2 ···. 243 ^ 2432 -... In the embodiment of the figure, each additional flow Qi i, Qj.2 ··· Οι.η is led from the manifold 25 in the additional flow pipes 20S |, 20s2 ... by supplying the valve 213 ^ 2132- .. directly to the outlet pipe 1 of the exhaust piping 11, 1 la2____ 20 Inlet pipe 1 lsj, 1 ls2 ··· further leads to a separate pipe 26at, 26a2 ... in the intermediate chamber 12, to which pipe 263 ^ 2632- .. is connected by an overflow pipe 220aj, 220a2 .... Overflow pipe 2203!, 22032 ... opens into an overflow reservoir 27 comprising a common collection space 28, a common air space 23, a common overflow threshold 29 and a common outlet 19 for the overflows 220ai, 220a2.

25

Figure 2B shows a section II-II of Figure 2A. The pipe 263 ^ 2632 · .. in the intermediate chamber 12 prevents the combined flow Q3 + Qj from mixing with the rest of the mass flow in the intermediate chamber 12.

Figure 2C shows a section III-III of Figure 2A.

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Fig. 3A shows an embodiment of the invention, in which the reference quantity Q4 is obtained by valves 3 ^, 3 ^ 2 ... 3 ^ located in the width direction of the top row of the turbulence generator 13 in adjacent turbulence tubes 13aj, 13a2 ....

Fig. 3B shows a section ΠΙ-HI from Fig. 3A.

• ·

Claims (18)

10 92228 A method in a headbox control, in which a flow (Q | i, Q4 2 --- Q4.11)> j00 ^ concentration of the flow 5 is adjustable at different points from the width of the headbox to the pulp suspension (M), whereby the desired rain is influenced by said flow. to a basis weight profile, characterized in that in the concentration yield of said flow (04.1,04.2 ···) introduced into the pulp suspension (M), two partial flows are combined by introducing an additional flow (0ι.ι, 0ι.2 ·) into the pulp suspension flow (Q3.1,03.2 ·· -Q3.il) ·· 0ι.η) »And that the mixture ratio of the combined flow is controlled by adjusting said additional flow 10 (Qi.i, Qi.2 - Qi.n) i by reducing or adding said additional flow restrictor at the valve (218 ^ 2 ^ 2 - .. In the method, after the junction of the additional flow (Qi.i, Qj.2 ···) and the mass suspension flow (Q3.1,03.2 ···), part of the combined flow (Qj Λ + 031; 012 + Q3.2) P ° is and the remainder as flow (Q4.1 , 04.2 ···) is introduced into the headbox pulp suspension (M), in which case, for example, as the total flow (Q1 + Q3) increases (when the Qjj flow increases in excess, i.e. the flow (Q2) exits the overflow and the flow (Q4) into the lip channel remains constant. Method according to Claim 1, characterized in that in the flow direction, after the overflow, a flow (Q4.i, Q4.2 ···) with a mixture ratio of 20 is passed from the intermediate chamber (12) to the turbulence generator (13) and in that method an additional flow (0 ^ ^ 0 ^ 2 - 01 ^) is introduced into the flow (Q3. ^ 3.2 - OJon, the concentration corresponds to the average mass suspension concentration of the headbox and that the additional flow (Qi.i, Qi.2-.) Is the water flow. Method according to one of the preceding claims, characterized in that the mixing of the combined flow (Qj ^ + Q3 j; Qj 2 + Q3.2; Q1.3 + Q3.3) in the width direction of the headbox is prevented by partitioning the headbox intermediate chamber (12) so that the headbox is divided at least across its width into zones (12a1,12a2 ... 12an), each zone being isolated from adjacent zones, thereby preventing combined flow (QM + Q31; Qt 2 + Q3.2; Q1.3 + Q3). 3) mixing in the • width direction of the headbox. • · 92228 11 Method according to one of the preceding claims, characterized in that the intermediate chamber (12) is divided by a partition wall (Ha ^ na ^ ..) into zones or blocks, in which method each zone (12ai, 12a2 ...) has its own overflow (22aj, 22a2). . ··). 5 Method according to one of the preceding claims, characterized in that the flow rate of each flow (Q4.i, Q4 2 ···) leaving the intermediate chamber (12) is controlled by adjusting the zones (12aj, 12a2 ...) associated with the intermediate chamber (12). (22aj, 22a2 ...). 10 Method according to the preceding claim, characterized in that the flow rate of the flow (Q4) is adjusted in the flow rate by adjusting the throttle of the valve (24a!, 24a2 ...) associated with each overflow (22aj, 22a2 ...). Method according to Claim 5, characterized in that the throttle of the valve (31aj, 31a2 ...) in the turbulence tube of the turbulence generator and thus the flow resistance of the flow (Q4) are controlled by adjusting the flow rate (Q4). Method according to one of the preceding claims, characterized in that in the method an additional flow (Qi.i * Qi.2 ···) is led directly to the manifold (11a}, 11a2 ...) of the headbox manifold (11) and from the manifold further through the tube (26aj, 26a2 ...) in the intermediate chamber (12) to the turbulence tube (13aj, 13a2 ...) of the turbulence generator (13) · Method according to one of the preceding claims, characterized in that an additional flow (Qi.i »Qi.2 *** Qi.n) is led from the manifold (25) to each of the additional flow pipes (203 ^ 2082 ... 2 (2) at different width positions of the headbox). ^). 1. T «» Apparatus in the headbox control, in which the device solution introduces a flow (Q4.i, Q4.2 ”* Q4.n) into the headbox pulp-30 suspension (M)« j00 ^ by adjusting the flow concentration, the basis weight of the paper can be adjusted to the desired width. , characterized in that 92228 12 that the flow (Q ^ Q ^ ···) to the pulp suspension (M) is formed from at least two partial flows, whereby the device arrangement comprises additional flow tubes (20a1,20a2 ... 20an) at different width positions of the headbox, through which the additional flow (tucxla) Ql j, Qj 2- "Qi.n) for the mass suspension flow (Q3.i» Q3.2 ·· -Q3.il) And that the device arrangement 5 handles means for preventing the combined flow (QL1 + Q31; Q12 + Q3-2 ;. ..) mixing perål in the width direction of the box, whereby the device solution covers the zones (12a1 (12a2 ...)) in the width direction of the headbox, whereby each zone (12a1,12a2 ...) has an overflow (22a1,22a2 ...), whereby by means of an overflow is kept in each zone12 ...) the flow rate of the combined mass flow 10 (Q3 + Q3) leaving the zone and thus the flow (Q4) constant, regardless of the amount of the additional flow (Q1.1.Q1.2 ···) introduced into the mass suspension flow (Q3). Device according to the preceding claim, characterized in that the additional flow channels (20a1,20a2 ...) comprise a flow control valve (21a1,21a2 ...) 15, by means of which the flow resistance and thus the flow (Q1.1 .Q1.2- ··) and that the zoning (12a1,12a2 ...) is carried out in the intermediate chamber (12). Device according to Claim 10 or 11, characterized in that each overflow (22a1, 22a2 ... 22an) associated with the different zones (12a!, 12a2 ...) feeds the means 20 for delivering the overflow flow, in which case in the flow rate of the combined flow (Q4 i, Q4 2 ...) leaving the intermediate chamber (12). Device according to one of the preceding claims 10 to 12, characterized in that each zone (12aj, 12a2 ...) of the intermediate chamber (12) is connected to a turbulence generator (13) at least one turbulence station in said relative width position. to the generator turbulence tube (13a1,13a2 ...). Device according to one of the preceding claims 10 to 13, characterized in that the device comprises an additional flow channel (20a1, 20a2 ...) which is connected 30 directly to the distribution pipe (1 species, 11a2 ...) of the distribution pipe (11). 92228 13 Device according to one of the preceding claims 10 to 14, characterized in that the partitioning of the flows (Qi.i, Qi.2; Q3.i> Q3.2 ···) after the junction is effected by means of a pipe (26ai, 26a2 ...), and that the pipe (26aj, 26a2 ...) is associated with an overflow connection (220a1,220a2 ...), which is preferably also a pipe and comprises a valve (24aj, 24a2 ...) 5, by means of which the overflow flow is regulated. (Q2.i »Q2.2 ···) · Device according to one of the preceding claims 10 to 15, characterized in that the overflow pipe (26a], 26a2 ...) is arranged in the intermediate chamber (12) in such a way that a combined flow (Qj + Q3) is passed from the distribution pipe to the turbulence system. to the generator turbulence tube. Device according to one of the preceding claims 10 to 14 or 16, characterized in that the device supplies a valve (31aj, 31a2 ...) in the turbulence tube of the turbulence generator, by means of which the flow resistance of the flow (Q4) and thus the flow rate of the flow (Q4) is regulated. Device according to Claim 10, characterized in that each overflow (22al522a2 ...) comprises an overflow threshold (18aj, 18a2 ...) which can be adjusted in height. 20. · · 92228 14