FI115647B - Method of controlling an inlet box in a paper machine / board machine and a construction of an inlet box in a paper machine / board machine - Google Patents

Description

115647

Paper Machine / Cardboard Headbox Adjustment Method and Paper Machine / Board Machine Headbox Design Förfarande för att reglera en inloppsläda i en pappersmaskin / cardboard mask avt inloppsläda 5 i en pappersmaskin / boardboard mask

The invention relates to a method of adjusting the headbox of a paper machine or board machine and to a headbox structure of a paper machine or board machine.

10

One of the major problems with a conventional headbox is the interconnection between the basis weight profile and the fiber casing profile when adjusting the basis weight by means of lip opening. Typically, the lip opening is more open at the center than at the edges, which will inevitably produce transverse velocities towards the machine centerline as the turbulence generator becomes approximately a smooth flow profile. Dilution control provides direct access to the lip opening for a straight flow profile with only consistency profile. However, the dilution control headbox is significantly more expensive than conventional and also requires its own dilution cycle in addition to the short cycle. It is an object of the present invention to provide a solution that achieves the benefits of a dilution control headbox 20 at a lower cost than a conventional headbox.

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In the solution according to the invention, the flow profile of the headbox is adjusted by the valves V1, V2, V3 ... at different widths of the headbox, preferably fitted after the headbox manifold. Preferably, the valves V15 V2, V3 ... are arranged equally. For example, at intervals of 60 mm, each of the single-row bellows pipes in each pipe so that all the flow from the manifold Jj passes through the valve system Vj, V2 .... With valve Vj, V2 ...

adjusting a flow profile that corresponds to the respective opening of the lip opening and the shape of its lip opening profile at the width of the lip opening. Hence, the lip opening profile *. the shape and the shape of the flow profile are the same, that is, where the lip opening with :: 30 larger flow cross-section brings more flow, and again at the lip opening with smaller flow cross-section, the valve flow is reduced . The headbox control thus utilizes the data of the lip opening profile 2 115647 to adjust the openings of the valves V15 V2 ... so that the flow profile shape corresponds as closely as possible to the lip opening profile multiplied by a specific scaling factor, which may be for each headbox.

5

In accordance with the invention, a single row barrel is used, from which the flow without the actual intermediate chamber is conveyed through a conical section to the turbulence generator, so that a controlled flow is led from one barrel pipe to two or three columns of the turbulence generator column. However, in the extreme case, the division may also be performed in 10 more rows of turbulence generators or only in one row of a turbulence generator. In this case, the number of valves in the extreme case is as high as possible. From the turbulence generator, the flow controlled by the valves is further directed to the lip cone and further to the lip opening, which is controlled by the tip strip by means of the adjustment spindles. Usually, the basis weight adjustment is performed by means of the spindle adjusting spindles.

15

The method of adjusting the headbox of a paper machine or board machine according to the invention and the headbox structure of a paper machine or board machine is characterized by what is claimed.

The invention will be described in the following with reference to the invention shown in the accompanying figures: 'explanatory graphs and a schematic drawing of the headbox according to the invention, which are not intended to be limited thereto'.

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FIG. 1A is a side view and a schematic representation of a headbox according to the invention.

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Figure IB is shown in Figure IA to the headbox of Figure IA arrow K • 4-4 '·'; from the direction, ie from above.

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Figures 2A-2E graphically show the values achieved / measured with the flow-controlled headbox of the present invention.

Figure 2A is a graph showing the flow profile after the turbulence generator. 5 The flow profile is formed by adjusting the shape of the flow profile with the valves in the width of the headbox to match the shape of the lip opening. The dashed line represents the graph and behavior of the flow-controlled headbox of the invention, and the solid line (vertical coordinate 1) represents the corresponding graphs in the case where the flow-controlling valves are not 10 and the flow profile is not adjusted. The horizontal axis represents the transverse position or position of the headbox and the vertical coordinate system shows the flow after the turbulence generator.

Fig. 2B is a graph showing the profile of the flow from the lip opening 15 across the width of the headbox, i.e. in the transverse direction of the headbox (CD direction). As shown in the figure, the horizontal coordinate system shows the horizontal position of the headbox, i.e. the CD position, and the vertical coordinate system shows the flow Q (flow rate / time unit) of the lip opening at each position.

Figure 2C shows the CD position (in meters), or headbox width position, in the horizontal coordinate system and the machine speed U (m / s) in the vertical coordinate system.

• * * '«' Figure 2D shows the horizontal position of the paper machine '·' in the horizontal coordinate system. ' and in the vertical coordinate system the associated jet transverse velocity is shown. The dashed lines * * * * · "25a show the values for the flow-adjusted headbox and the dashed values for the flow control valves Vj, V2 ...

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Figure 2E shows an orientation profile. The horizontal coordinate system shows the transverse position of the headboard * · '* and the vertical coordinate system shows the orientation angle in degrees with respect to each horizontal position.

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Figure 3A illustrates a flow-controlled headbox.

Fig. 3B shows the tip list and lip opening structure of the flow controlled headbox.

5

Figure 3C shows the transverse CD drive in the horizontal coordinate system and the flow (flow rate / time unit) in the vertical coordinate system. The function fj represents the flow function over the width of the headbox not corrected by the valves VltV2 ... The function f2 represents the corrected flow function after the valves V1, V2 ....

10

Fig. 4A shows the width position of the headbox in the horizontal coordinate system and the dimensionless lip opening in the vertical coordinate system.

Figure 4B shows the headbox width position in the horizontal coordinate system and the vertical profile in the coordinate system shows the velocity profile at the trailing edge of the turbulence generator at the headbox width.

Figure IA shows the flow rate provided for the headbox 10 according to the invention from the side, and Figure IB is shown in Figure headbox of Figure IA, the direction of the arrow K i a!.! 20 from above. According to the invention, the headbox comprises a manifold J1? which can be constant in cross-section across the width of the headbox because the valves Yl5 V2 ...

• t "adjusts the total flow from the manifold forward or tapering to provide approximately the same flow conditions to the inlet side of each of the • t · 'll * valves. The manifold Jj has a single row bellows 11 having 1a1 (lla2 ... valves Vj, 25 V2) ... are fitted The valves V1, V2 ... are conventional throttle valves for adjusting the flow rate (flow rate / time unit) After the single row bellows, there is a cardboard expansion section 12 through which the flow is led from each in the embodiment of the figure, the mass flow Q from the valve Vj, 30 V2 ... is divided into each of the two valves of the turbulence generator 13 and of these 13; This way, the flow is preferably dispersed into at least two vertical rows, and yet sufficient control t is achieved. From the turbulent sigenerator 11, the flow is led to a lip cone 14, i.e. a lip duct tapering towards its end, through which the flow enters the lip opening 15, which is controlled by the tip strip 16 by means of its adjusting spindles 17aj, 17a2 .... The control spindles 5 adjust the lip opening and thus the basis weight and adjust the flow profile from the valve valve V1 (V2 ...) to the flow profile, however, by scaling or multiplying the flow profile by a given scaling factor. Thus, the flow 10 is provided more at the points of the lip opening having a larger flow cross-section and less at the points with the smaller cross-sectional area. .

15 TECHNICAL IMPLEMENTATION

The invention combines tip list and flow control. Flow control requires no information other than lip profile when the scaling factor is once attached. If the future measurement of the orientation angle profile is successful on-line, it could · · · 20 be used to fix the optimum scaling factor and to verify the adjustment while running '' · *, but it is not necessary.

• · ·; , * Valve control achieves the desired turbo flow profile, minimizing the transverse velocity of the lip · · · · ·> and hence the paper fiber orientation angles

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With 25 lip opening profiles. When the flow profile from the turbo is the lip profile. . shape and flow min-max variation in the case of Figure 2A about 10%, the lip flow (shown in Figure 2B) and machine direction speed (shown in * 2 ♦ / _ in Figure 2C) slightly, but the greatest effect on control is the transverse speed (shown 2D), which can be eliminated almost completely. Corresponding orientation angle-. 30 is shown in Figure 2E. As a reference, the figures have a solid line for the · · 'direct flow profile after the turbulence generator.

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ADJUSTED FLOW PROFILE

For a given lip opening profile, an optimal flow profile can be found to eliminate fiber orientation angles. The optimum flow profile is shaped as a lip opening 5, scaled with a suitable constant so as to properly account for changes in profiles in the lip channel (flattening of the flow profile from the turbo and development of the "desired" flow profile of the lip profile). Thus, finding the optimum adjustment is in fact seeking the optimal scaling factor so that the transverse velocities are minimized.

The idea of the present invention is to utilize existing technology to adjust an optimum flow profile for lip duct inflow (Fig. 2A), which is in the form of a lip opening profile and eliminates transverse lip velocities (Fig. 2D) and thus paper orientation angles (Fig. 2E). In addition, the machine mouth-15 nanometer speed is more uniform than that of the conventional headbox (Fig. 2C). shower / wire ratio and thus the formatting and tensile strength ratio.

Using the lip profile shape in the adjustment allows for quick adjustment because the adjustment system knows the lip profile directly without the need for 20 indirect measurements of finished paper at the dry end of the machine. The scaling factor between the lip opening profile and the corresponding optimum flow profile depends on the lip channel geometry, so it has to be specified per headbox. It can be solved I * by either numerical simulation of lip channel flows or current response times »· ·

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like experiments.

25

BENEFITS

• * *, ·. (A) The flow-controlled headbox achieves the following benefits: '1 · Adjusting the basis weight profile corresponding to the drying shrink profile without a significant fiber orientation profile (Figure 2E). From the wire section, it does not make much difference whether> · * * · 7 115647 has a constant flow and adjusted consistency profile (dilution strain) or constant consistency and controlled flow profile (idea of the present invention).

• The velocity of the lip jet in the machine direction is constant, since more flow is introduced where the lip opening is more open, which results in a constant machine direction speed 5 (Fig. 2C).

(B) No additional inputs are required in the flow-controlled headbox because the same effect is obtained by controlling the flow to the lip duct. Ts. the auxiliary feed would be smoothly supplied with the adjusted flow profile.

10 (C) In a conventional headbox, the fiber orientation angles are toward the machine centerline and the jet / wire ratio is lower in the center of the machine than at the edges, with the lip opening more open in the center than the edges. As shown in Figure 2C, the flow profile can influence not only the orientation, but also the jet / wire ratio and thus the jet / wire ratio. and tensile strength. However, the fiber orientation and shower / wire ratio control are interdependent in the flow controlled headbox. As shown in Figures 2C and 2E, they can simultaneously be as smooth as possible (better than in a conventional headbox), but if one were to profile one as desired, the other would also change. However, it would be possible, for example, to adjust the machine direction tensile strength at the edges of the paper web to greater than the center web to provide runnability and / or main tension [t] [better.

»« · (D) Flow controlled headbox is cheaper than conventional headbox 25 or dilution headbox because, ··· 1 · No dilution cycle required • · · 2. Flow control valves are simple throttle valves, », ·, 3. Single row manifold significantly cheaper than the current multi-line,

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4. Intermediate chamber is no longer needed because the manifold does not become an incorrect flow profile-30, · * 5. Additional feeds are omitted because they are part of the adjusted flow profile, «1 t 8 115647 6. The form of the manifold can be simplified since lower operating costs for the bypass, since a few percent is enough for the bypass, eliminating the 10% bypass required in the conventional headbox.

5

Fig. 3A shows and illustrates a headbox structure according to the invention and Fig. 3B shows the shape of a lip opening. The figure shows the shape of the lip of the headbox. The shape of the bottom bar defining the lip opening is linear and the upper surface of the lip is limited by the curved edge of the tip. Generally, the 10 lip openings are at their maximum opening in the centerline of the headbox. Figure 3C shows the flow quantities corresponding to the flow graph fj in the vertical coordinate system, which can be read directly from each headbox width position in the vertical coordinate system. The figure shows the flow rates Q1, Q2 ... (liters / minute) at different width points Y1 (Y2, Y3, Y4, Y5 ...) of the headbox lip opening corresponding to a headbox where the flow profile 15 has not yet been adjusted according to the invention by valves V1, V2, V3 ... Flow Q1, Q2 ... is the mass flow out of the lip opening.

Figure 3C also shows the corrected flow function f2, whereby the corrections are made by adjusting the valves V}, V2 .... Thus, in Figure 3C, an embodiment is shown which, when executed with the correction valves V (, V2 ..., adjusts all the valves, however, by increasing the flow separately. However, in practice, the preferred embodiment is to reduce the flow through the other valves and; In such an embodiment, the total flow rate of the headbox will be kept as constant as possible and deviations from the average flow rate will be kept small, thereby keeping the stern supply pump operating mode constant, i.e. without increasing or decreasing pressure on the pump.

The average flow rate corresponding to the average lip opening is then calculated. The coordinate system (Y coordinate system) is fixed to this average • »*

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! opening the lip opening and forming a tip list approximating the position of its leading edge 16 '. 30 wavy function bd (y). A solution illustrating said preferred embodiment of the control is shown in Figures 4A and 4B below. The graphs fj, f2 represent flows Q1, Q2 ... out of the lip opening.

Figures 4A and 4B illustrate an embodiment of the control according to the invention. Figure 5 shows a preferred embodiment of the adjustment, first calculating the average opening of the lip opening and the corresponding dimensionless lip opening shape. Figure 4A shows the width of the headbox in the horizontal coordinate system and the dimensionless lip opening in the vertical coordinate system. The horizontal coordinate b represents the average lip opening and bd (y) is a dimensionless lip opening with a mean of zero. Thus, from the actual lip opening 10, a dimensionless shape bd (y) = (b (y) / B) -1 is first calculated, where b (y) is the original true lip opening, B is the mean lip opening and bd (y) is a dimensionless lip opening having a mean of zero .

After this, the optimal scaling factor c is sought.

15

The optimal scaling factor c is selected for each headbox so that no transverse currents occur and the fibers are then parallel. In this case, the transverse velocity of the flow is as close as possible to zero and the machine velocity of the mass flow is as constant as possible. The coefficient c can be experimentally selected by looking at • · 20 the finished paper or board and its fiber directions and, when the fibers are •> * parallel, the coefficient c used for that test run. This coefficient represents * t then the scaling factor c associated with that headbox.

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In Fig. 4B, a dimensional velocity profile corresponding to c is calculated at the trailing edge of the turbulence generator k · * 25: Uin (y) = [1 + c - bd (y)], where U (m / s) is an average. flow rate and c is the dimensional constant.

»T * • · ·. ·. From the corrected velocity profile Uin (y), the flow profile Q (y) is calculated to the manifold *! from valves V1.V2 ... Knowing the velocity profile at the headbox width and knowing the 30 tip adjustments associated with that velocity profile, the flow profile Q (y) can be calculated at the respective headbox width point. The graph for the corrected flow profile may be similar to the graph of function f2 in Figure 3C.

115647 ίο Thus, when we have a non-flow controlled headbox and the tip mold comprises a certain 5 shapes of the headbox width with the largest lip opening, it flows more through (1 / min) than those with a smaller opening or smaller lip opening. Thus, when the flow of throttle strokes more towards a certain direction than on the other hand, the flow tends to turn in the direction where the flow resistance is lower. Thus, the fiber orientation tends to change due to the aforementioned side flow. The invention has been realized to perform flow rate correction based on the lip aperture shape and thus on the tip position adjustment position. Thus, by utilizing the orifice shape, a correction factor is applied to the uncorrected flow profile by a certain factor c. This correction for flow rates is in the order of a few percent, but its effect on orientation angles is crucial. The fibers are machine-oriented.

Thus, as described above, in a given driving situation, the pumping pressure applied to a certain mass distributor and certain valve V1; With the V2 ... adjusting positions placed on the headbox bogie along its width, the mass flow flow profile at different headbox widths is detected and then the shape of the tip edge associated with the 20 tip tip adjustment position is detected from the headbox width. The method then assigns to the valves * * '· (Vj, V2 ...) new setpoints that implement the corrected flow profile calculated from a · lip aperture approximating function e.g. bd (y) multiplied by a given headbox-selected scaling factor c, the scaling factor »· · * 25 c has been determined experimentally so that there is no orientation error in the fibers and. . The lateral flows are minimized so that the fibers are oriented in the machine direction and the machine speed V (m / s) of the mass flow I «» is as constant as possible.

In summary, it can be said that in a preferred embodiment of the invention the headbox. 30, through the flow-adjusting valves, the flow rate is preferably: · * such that for those headbox widths with a smaller orifice opening of 11,55647, the flow rate is reduced and for the headpiece flow rate, increasing the flow rate when the reference point is an uncorrected flow profile situation.

5

The flow profile can also be adjusted as follows: a) Observe the tip position adjustment position and encounter the headbox width at which the tip position is at its lowest, ie the lip opening at its lowest, no additional 10 flows are obtained. Additional flow is introduced at other locations along the headbox width and the larger the lip opening at that location.

The opposite mode of adjustment is as follows: b) Detecting the shape of the tip strip and at the position of the headbox width at which the tip tip opening is greatest does not result in a change in the flow profile. For other points of the headbox width, a corrected flow is introduced by increasing the throttling, i.e., those points where the mouthpiece is smaller are throttling more flow than those where the mouthpiece is larger.

20 c) The adjustment method may be between a) and b) by selecting a particular lip opening between the maximum lip opening and the minimum lip opening with the calculation • · • * »*; '* is performed as shown on page 12. Adjustment of the valves V1, V2 ... is performed by increasing the throttling of the valves V1, V2 ... at the * 25 headbox widths with smaller apertures than that of the selected lip opening. . larger openings than that selected lip opening will reduce _T # the throttling of the valves Vj, V2 ... at their respective openings. Prior to the adjustment in the initial setting, the valves V1, V2 ... are preferably set to the middle adjustment position, whereby the adjustment margin '·; both ways are enough.

»T · t · 30 12 115647 The adjustment method is most advantageously as follows.

The position of the tip or lip opening is observed and the maximum and minimum opening of the lip are observed. From the 5 vertex positions implementing the above openings, select one of the vertex positions between the maximum and minimum openings and make the adjustment as follows. At those points in the headbox width where the tip strip is above the selected tip strip position, i.e., the lip opening is larger than the selected opening, more flow is introduced, and in those headbox widths where the tip strip is in the lower opening 10 position.

In all of the above adjustments a), b) and c), the calculation model is the same as the one described above for the most advantageous case, that is, based on the average lip opening and average tip position. Ie 15 - first observe the position of the tip list, then at certain valve positions, for example the average control position, the velocity profile of the outflow from the turbulence generator, then calculate the corrected flow velocities by adding the selected orif an approximating function with a scaling factor selected on a headbox basis such that, after correction, it terminates; , * as a result of the fiber orientation, an error-free flow is obtained, that is, a flow in which the fibers are located in the machine direction.

25th • t Thus, once a corrected flow rate profile has been calculated, this * * can be used to calculate the corrected flow for each headbox width by knowing. *, The position of the toothed ridge, and the corrected flow rate calculated for each tooth.

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Claims (9)

115647 A method for adjusting the headbox (10) of a paper machine / board machine, wherein the mass flow support (Jj) is used to derive a mass flow through valves (Vj, V2 ···) set at different width points 5 of the headbox. (Jp substantially all the mass flow is passed so that it passes through the valves (V1, V2 ...) and thus the headbox flow profile is adjustable by adjusting or decreasing the throttling of the valves (V1, V2 · ···), determining the shape of the lip opening of the headbox, calculating the flow profile of the headbox by multiplying the lip shape of the headbox by a constant (c) determined by the lip channel geometry and adjusting the flow profile h of the headbox using valves (Vj, V2.) 15 in the shape of a hole profile Method according to Claim 1, characterized in that the method adjusts the flow profile across the headbox width by means of a valve (Vj, V2 ···) such that the valves (Vj, V2 ...) are first set at a particular position and at that particular position t,> '. preferably the center valve position is used to measure or calculate the flow profile after the turbo: 20 lens generator with a certain tip adjustment, and that the method then performs a correction of the flow profile with the valves (Vj, V2 ...) so that the flow is corrected. ': The map profile is calculated from that uncorrected flow profile and the associated lip opening. • · «· The method of claim 1, the headbox of a paper machine / board machine; (10) in a method wherein the headbox comprises flow control valves * f (Vj, V2 · ..) across the width of the headbox, wherein the method directs substantially all flow through the flow valves (Vj, V2 ···) , whereby the valves (Vj, V2) control the flow rate of the mass flow from the manifold supports: 30 profile at headbox width (flow rate / time unit / headbox width), •: characterized in that the flow through the valves (Vj, V2 ···) is 115647 first uncorrects an uncorrected flow profile after the turbulence generator at a headbox width corresponding to a particular tip list adjustment position, and that the correction associated with that tip list opening, i.e. the tip list adjustment position, is performed with the point can be calculated from the lip opening, that is, the position of the vertex at that point, which opening and thus the position of the vertex is multiplied by a given scaling factor (c), and which scaling factor (c) is experimentally selected so that the flow profile after valves (Vj, V2 ···) is constant across the machine and that no cross currents occur. 10 A method according to any one of the preceding claims, characterized in that the valves (Vj ^ · ·) adjust the flow rate (flow rate / time unit) of the mass flow support at each width section of the headbox (10), adjusting the flow profile across the headbox width After (vi> V2 · · ·), the lip opening (15) of the headbox (10) is scaled with a constant, thereby providing more flow with larger opening (15) and lower opening (15), respectively, less flow is introduced, whereby the flow profile has the same shape as the lip opening profile. The method of adjusting the headbox (10) of the paper machine / board machine according to the preceding claim, characterized in that the headbox (10) comprises flow control valves (V ^, λ). ^ ...) the width at which the valves (Vj, V2 ···) adjust the flow (volume / time unit) of the mass flow from the manifolds at each width of the headbox (10), whereby the flow is controlled by the valves 25 (Vj, V2 ···) so that more flow is applied to the lip opening (15), whereby the opening (15) is larger than the average opening, and correspondingly, where the opening is smaller than the average opening, it is provided with less flow, the corrected flow profile graph has the same '·; · 'Shape other than a lip profile, the method first detecting an uncorrected flow profile (flow rate / time unit: flow unit) from the headbox :: 30 turbulence generator and then correcting it to a flow profile across the width of the headbox 115647 ... thereafter, the lip opening (15) of the headbox (10) is scaled with a constant. A method according to any one of the preceding claims, characterized in that conventional throttle valves (V1, V2 ...) are used for adjusting the flow profile, which are arranged at regular intervals at different widths of the headbox (10) over the entire width of the headbox. Method according to one of the preceding claims, characterized in that the valves (Vj, Vj) 10 are disposed at different widths on the headbox (10) in a single row barrel (H). A method according to any one of the preceding claims, characterized in that the method uses a headbox (10) in which the valves (Vj, V2 ...) are placed in a single row barrel (11) immediately after the manifold (Jj), and having a flow profile defined by the lip opening (15) is led from the valves (Vj, V2 ···) to the tubes (13aj, 13a ^ 2 ···) of the turbulence generator (13) and further to the lip channel (14) and the lip channel (14) and lip opening ) through the forming wire (Hj). <t Method according to one of the preceding claims, characterized in that the method adjusts the basis weight of the paper by adjusting the tip strip (16) with the adjusting spindles (17a ^, ': 1¾ ....). 115647