Method and device in the regulation of a headbox

Abstract

A method and device in the regulation of a headbox. The headbox includes a pulp inlet header, after the pulp inlet header, seen in the pulp flow direction, a distributor manifold whose pipes are opened into an intermediate chamber. The headbox comprises an attenuation chamber placed in connection with the intermediate chamber and, after the intermediate chamber, a turbulence generator having tubes which are opened, at their outlet end, into a discharge duct and, at their inlet end, into the intermediate chamber. In the method, into different positions along the width of the headbox, a pulp suspension flow is introduced, the concentration of this flow is adjustable by combining two component flows. In the method, in the regulation of the concentration of the flow passed into the pulp suspension, two component flows are combined by into the pulp suspension flow introducing an additional flow. The mixing ratio of the combined flow is regulated by adjusting the additional component flow. In the method, the additional component flow is passed into the pulp flow taken out of the inlet header.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a method and device in the regulation of the headbox of a paper/board machine, by means of which method and device it is possible to reliably act upon the grammage profile of the paper reliably across the width of the paper/board web and advantageously, it is also possible to act upon the fiber-orientation profile of the paper/board web across the width of the paper/board web.

As is known from the prior art, the discharge flow of the pulp suspension out of the headbox should have a uniform velocity in the transverse direction of the paper/board machine and. A transverse flow produces distortion of the fiber orientation and adversely affects the quality factors of the paper produced, such as anisotropy of strength and stretch. The level and variation of anisotropy in the transverse direction also affect the printing properties of the paper. In particular, it is an important requirement that the main axes of the directional distribution, i.e. orientation, of the fiber mesh in the paper coincide with the directions of the main axes of the paper and that the orientation is symmetric in relation to these axes.

At the edges of the pulp-flow duct in the headbox, a smaller amount of pulp flows. This edge effect produces a very strong linear distortion in the fiber-orientation profile. Profile faults in the turbulence generator of the headbox usually produce a non-linear distortion in the fiber-orientation profile inside the lateral areas of the flow ducts.

Attempts have been made to compensate for an unevenness of the grammage profile arising from the drying-shrinkage of paper by means of a crown formation of the slice, so that the slice is thicker in the middle of the pulp jet. However, it is a phenomenon in the manufacture of paper that when the paper web is dried, it shrinks in the middle area of the web to a lower extent than in the lateral areas. The shrinkage is typically in the middle of the web about 4% and in the lateral areas of the web from about 5% to about 6%. This shrinkage profile produces a corresponding change in the transverse grammage profile of the web. As a result of the shrinkage, the dry grammage profile of a web whose transverse grammage profile was uniform after the press is changed during the drying so that, in both of the lateral areas of the web, the grammage is slightly higher than in the middle area. As known from the prior art, the grammage profile has been regulated by means of the profile bar so that the profile bar of the headbox is kept more open in the middle area of the headbox than in the lateral areas of the headbox.

By means of this type of arrangement, the pulp suspension is forced to move towards the middle area of the web. However, there circumstances further affect the alignment of the fiber orientation. The main axes of the directional distribution, i.e. orientation, of the fiber mesh should coincide with the directions of the main axes of the paper, and the orientation should be symmetric in relation to these axes. In the regulation of the profile bar, a change in the orientation is produced as the pulp suspension flow receives components in the transverse direction.

Regulation of the lip of the headbox also produces a change in the transverse flows of the pulp jet even though the objective of the regulation is exclusively and only to affect the grammage profile, i.e. the thickness profile of the pulp suspension layer that is fed. Thus, the transverse flows have a direct relationship with the distribution of the fiber orientation.

From the prior art, specific devices are known by whose means attempts are made to regulate the fiber orientation, and other devices are known by whose means attempts are made to regulate the grammage profile of the web. However, when the grammage profile is regulated in a prior art devices by means of the profile bar, the fiber orientation in the web is unavoidably also affected at the same time.

From the prior art, a method is known in the headbox of the paper machine to control the distortion of the fiber orientation in the paper web. In such a method, medium flows are passed into lateral passages placed at the level of the turbulence generator of the headbox, and, by regulating the magnitudes and the mutual proportions of these flows, the transverse flows of the pulp suspension are affected, and thereby the distortion of the fiber orientation is regulated. By means of the flows introduced into the lateral passages, a transverse flow velocity is produced which compensates for the distortion of the fiber orientation.

From the assignee's Finnish Patent Application No. 884408 of earlier date (corresponding to the assignee's U.S. Pat. No. 5,022,965, the specification of which is hereby incorporated by reference herein), a method is known in the headbox of a paper machine to control the distribution of the fiber orientation of the paper web in the transverse direction of the machine. In the method described in FI '408, the transverse velocity component of the discharge jet is regulated by appropriately aligning the turbulence tube of the turbulence generator.

By means of the above mentioned prior art methods for controlling the fiber orientation in the paper web, it is usually possible to control only the linear distortion profiles. The prior art methods are thus suitable for the control of the fiber orientation, but, when they are used, commonly even a large non-linear residual fault remains in comparison with an even distribution of the orientation. The prior art methods are also well suitable for basic regulation of the distortion of the orientation. However, by means of the prior art methods, it is not possible to regulate individual faults which may occur in the orientation in the middle area of the web and which arise, e.g., from defects in the pipe system of the turbulence generator.

A number of methods are also known for the regulation of the profile bar, in which, while the grammage profile is measured, the position of the profile bar in the headbox of the paper machine is changed. In addition, by means of the profile bar, the thickness of the pulp suspension discharged onto the wire, and thereby, the grammage of the paper web, are affected. In the manner described above, this regulation produces faults in the orientation because, by means of the regulation, the flow is throttled elsewhere, whereby components of transverse velocity are produced in the flow.

In the invention described in the assignee's Finnish Patent No. 50,260 (corresponding to U.S. Pat. No. 3,791,918), the headbox has been divided across its width, in a direction transverse to the main flow direction, into compartments by means of partition walls. In this headbox, in an individual compartment, there is at least one inlet duct for the passage of a component flow to feed diluting water into the pulp flow.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide novel solutions for the problems discussed above.

It is also an object of the present invention to provide a new and improved method and device by whose means the consistency of the pulp suspension at different positions of width of the web, i.e., in the transverse direction of the web, can be reliably regulated so that the diluting flow remains at the position of width into which it is introduced and is not shifted in the cross machine direction into another compartment.

The aim of the consistency-regulation of grammage is to eliminate the interdependence between the transverse grammage profile and the fiber orientation profile. When the transverse profile of grammage is regulated by profiling the consistency, for example, when 0-water is used, the maximal amount of diluting water is 50% of the overall flow quantity in the consistency zone. In order that this water amount should not produce transverse flows and eliminate the object of the consistency regulation, the amount of diluting water must be compensated for so that the flow quantity coming from the turbulence generator is invariable and constant in the transverse direction of the machine. The mixed/consistency-regulated flow quantity should thus be kept invariable and constant.

In a preferred embodiment of the method and device in accordance with the invention, the diluting liquid is passed directly into the turbulence tube, into its mixing chamber. The introduced diluting flow displaces the pulp flow that has been introduced from the intermediate chamber and that is combined with the diluting flow by its own quantity. Thus, the sum flow remains invariable.

In a second preferred embodiment of the invention, it is also possible to regulate the flow quantities in different positions of width of the headbox, i.e., in the transverse direction of the headbox, and, thus, it is possible to regulate the fiber orientation in the overall flow in the direction of width of the paper machine. In this second preferred embodiment, the flow is introduced, on the whole, into the pipe system after the pulp inlet header, and into the system of distributor pipes. Further, the headbox is divided or partitioned into compartments in the direction of width, and a pulp flow and a diluting flow are passed into each compartment, and after the point of combination (of the pulp flow and the diluting flow) there is an overflow into an attenuation chamber. In this manner, at each position of width, besides adjustment of the grammage of the paper, it is also possible to regulate the pressure of the flow, i.e. the flow quantity or rate, at each particular position of width, and thus, the fiber orientation of the paper.

In the following, the invention will be described in detail with reference to some exemplifying embodiments of the invention illustrated in the figures in the accompanying drawing, the invention being by no means strictly confined to the details of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the invention and are not meant to limit the scope of the invention as encompassed by the claims.

FIG. 1A is a sectional side view of the headbox of a paper/board machine in accordance with the invention, into which 0-water is passed along a duct of its own.

FIG. 1B shows the area X in FIG. 1A.

FIG. 1C is a sectional view, partly in section, taken along the line I--I in FIG. 1A.

FIG. 1D is a sectional view, partly in section, taken along the line II--II in FIG. 1A.

FIG. 1E is a sectional view taken along the line III--III in FIG. 1A.

FIG. 2A shows the construction of the mixing chamber of a turbulence tube in the turbulence generator on an enlarged scale.

FIG. 2B is an enlarged sectional view taken along the line IV--IV in FIG. 2A.

FIG. 3 shows a second embodiment related to the mixing chamber of a turbulence tube.

FIG. 4A shows a third preferred embodiment of the invention related to the mixing chamber of a turbulence tube in the turbulence generator.

FIG. 4B is an enlarged sectional view taken along the line V--V in FIG. 4A.

FIG. 5A shows an embodiment of the invention in which the diluting flow is passed into the system of distributor pipes. FIG. 5A is a schematic illustration of the headbox of a paper/board machine, into which headbox 0-water is passed along a duct of its own so as to regulate the mixing ratio at a certain position of width of the headbox and in which headbox an intermediate chamber comprises overflows so as to keep the flow quantity invariable as the mixing ratio is regulated.

FIG. 5B is a sectional view taken along the line VI--VI in FIG. 5A.

FIG. 5C is an axonometric illustration in part of the block construction in the direction of width of a paper/board machine as shown in FIGS. 5A and 5B.

FIG. 6A is an illustration of principle and a sectional view of the headbox of a paper machine, which headbox comprises separate zones or blocks carried into effect by means of pipe connections and formed at different positions of width across the headbox of the paper/board machine.

FIG. 6B is a sectional view taken along the line VII--VII in FIG. 6A.

FIG. 6C is a sectional view taken along the line VIII--VIII in FIG. 6A.

FIG. 7A shows an embodiment of the invention in which the flow quantity is regulated by means of valves arranged in the turbulence tubes in the upper row in the turbulence generator.

FIG. 7B is a sectional view taken along the line IX--IX in FIG. 7A.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the accompanying drawings wherein like reference numerals refer to the same elements, FIG. 1A shows the headbox of a paper/board machine in accordance with the invention, which headbox comprises, proceeding in the flow direction S of the pulp suspension M, an inlet header 10, a discharge duct 14 and conduit means for passing a pulp flow from the inlet header 10 to the discharge duct 14. The conduit means include a distributor manifold 11, in which there are distributor conduits or pipes 11a.sub.1.1,11a.sub.1.2, . . . ,11a.sub.2.1,11a.sub.2.2, . . . placed one above the other and alongside one another, an intermediate chamber 12, a turbulence generator 13, which comprises a number of turbulence conduits or tubes 13a.sub.1.1,13a.sub.1.2, . . . ,13a.sub.2.1,13a.sub.2.2, . . . placed side by side and alongside one another, and a discharge duct 14, into which the turbulence tubes 13a.sub.1.1,13a.sub.1.2, . . . ,13a.sub.2.1,13a.sub.2.2, . . . of the turbulence generator 13 are opened. The discharge duct 14 is defined by a stationary lower-lip wall 15 and by an upper-lip wall 16 pivoting around an articulated joint N. In the following, when the invention is described and when a paper machine is spoken of, it is obvious that a board machine and its headbox may also be concerned.

Further, the headbox in accordance with the present invention comprises an attenuation chamber 17 which opens into the intermediate chamber 12. The attenuation chamber 17 extends across the entire width of the machine, i.e., the transverse direction of the headbox, and the intermediate chamber 12 communicates through a duct 18 with an interior space D of the attenuation chamber 17. When the pressure in the space D is regulated, the pressure level of the pulp M present in the intermediate chamber 12 is also regulated, e.g., possibly being maintained at the invariable constant level determined by the attenuation chamber 17. As shown in FIG. 1A, an overflow Q.sub.2 is provided through the duct 18 into the attenuation chamber 17. Over the overflow threshold T, the flow Q.sub.2 enters into a trough G and further is displaced out of the trough G through end ducts E. The pressure is passed into the space D through a flange joint M.

The equalizing chamber 17 comprises an inner pressure space D, to which a flow Q is provided for the pulp M out of the intermediate chamber 12. Pressure is introduced into the space D in the equalizing chamber 17, and the discharge of the pressure out of the space D is regulated by means of a separate valve. Thus, by means of the pressure present in the space D, the level of the pulp M passed into the equalizing chamber (flow Q.sub.2) in the space D is regulated, and so also the pressure that acts further upon the pulp M in the intermediate chamber 12. At both ends of the trough G placed underneath the attenuation chamber 17, there are drain ducts E, the flow Q.sub.2 into the equalizing chamber 17 passing further out through the trough G and back to the pulp circulation. By means of the flow Q.sub.2, the excess amount of the pulp M is removed from intermediate chamber 12 that must be displaced when a diluting component flow Q.sub.1 is introduced into the mixing point in order that the combined flow (Q.sub.1 +Q.sub.3) remains at its invariable value.

FIG. 1E is a sectional view taken along the line III--III in FIG. 1A. As shown in FIG. 1E, the equalizing chamber 17 extends across the entire machine width and, thus, from all positions of width of the equalizing chamber, there is a duct connection 18 into the intermediate chamber 12 extending across the machine width. The turbulence generator 13 is placed expressly after the intermediate chamber 12.

In accordance with the present invention, a diluting component flow having subcomponent flows Q.sub.1.1,Q.sub.1.2, . . . ,Q.sub.1.n is passed in a headbox of the sort mentioned above into the turbulence generator 13. Each diluting subcomponent flow Q.sub.1.1,Q.sub.1.2, . . . , Q.sub.1.n is passed into different positions of width (in the transverse direction of the headbox) in the turbulence generator 13, preferably into respective turbulence tubes 13a.sub.3.1,13a.sub.3.2, . . . ,13a.sub.3.n in the middle level. In this manner, by means of the additional flow, i.e. the diluting subcomponent flows Q.sub.1.1,Q.sub.1.2, . . . ,Q.sub.1.n passed into the compartment formed by the respective tube 13a.sub.3.1,13a.sub.3.2, . . . ,13a.sub.3.n placed in that position of width, the grammage of the paper is regulated at the position of width concerned as the additional flow is mixed, at each particular position of width, with the pulp M, constituted by its subcomponent flows Q.sub.3.1,Q.sub.3.2, . . . ,Q.sub.3.n which has been passed out of the intermediate chamber 12 into the turbulence tube 13a.sub.3.1,13a.sub.3.2, . . . , 13a.sub.3.n in the turbulence generator 13.

The turbulence generator 13 shown in FIG. 1A comprises a number of turbulence 25 tubes placed side by side in the direction of width and in the vertical direction. The turbulence tubes 13a.sub.3.1,13a.sub.3.2, . . . ,13a.sub.3.n of the middle level are connected with an additional-flow duct 20a.sub.1,20a.sub.2, . . . ,20a.sub.n, preferably a 0-water duct and preferably also a pipe. Each flow duct 20a.sub.1,20a.sub.2, . . . , 20a.sub.n comprises a valve 21a.sub.1,21a.sub.2, . . . ,21a.sub.n by whose means the throttle of the additional diluting subcomponent flows Q.sub.1.1,Q.sub.1.2, . . . ,Q.sub.1.n are regulated. In addition, the flow velocity is thus regulated and the flow quantity is regulated that is passed out of the diluting-water inlet header 19 into the turbulence generator 13 and into each particular compartment constituted by the tube 13a.sub.3.1, 13a.sub.3.2, . . . , 13a.sub.3.n. When the additional diluting subcomponent flows Q.sub.1.1,Q.sub.1.2, . . . , Q.sub.1.n enter into the respective turbulence tubes 13a.sub.3.1, 13a.sub.3.2, . . . , 13a.sub.3.n, it is mixed in the mixing chamber 130 of the turbulence tube with a respective one of the pulp M subcomponent flows Q.sub.3.1,Q.sub.3.2, . . . ,Q.sub.3.n passed out of the intermediate chamber. However, in accordance with the invention, it is possible that only one set of respective subcomponent flows, e.g., Q.sub.1.1 and Q.sub.3.1, are mixed together in a regulation proportion.

In accordance with the present invention, the amount of additional component flow Q.sub.1 that is introduced is reduced from the flow quantity Q.sub.3 of the pulp M passed out of the intermediate chamber 12. Thus, the sum flow Q.sub.4 (=Q.sub.1 +Q.sub.3) remains invariable during the regulation while the mixing ratio is regulated by regulation of the additional flow by means of the respective valves 21a.sub.1,21a.sub.2, . . . ,21a.sub.n. The excess flow of Q.sub.3 is passed as the flow Q.sub.2 into the attenuation chamber D and further out of that chamber and back to the pulp circulation.

FIG. 1B is a separate illustration of the area X in FIG. 1A. Into the turbulence tubes in the middle layer of the turbulence generator 13, a pulp component flow Q.sub.3 having a normal concentration enters from the intermediate chamber 12 of the headbox. In the turbulence tubes in the turbulence generator 13, each additional component flow Q.sub.1 is mixed efficiently with the pulp component flow Q.sub.3. The additional subcomponent flows Q.sub.1.1,Q.sub.1.2, . . . , Q.sub.1.n are passed into the mixing chamber 130 in the turbulence tubes of the turbulence generator 13. By means of the mixing chamber 130, uniform mixing of the component flows Q.sub.1 and Q.sub.3 is permitted, and the uniform pressure maintained in the intermediate chamber 12 is passed to the mixing point. The quantity of the combined component flows (Q.sub.1 +Q.sub.3) remains invariable, while the mixing ratio is regulated by means of the additional component flow Q.sub.1.

In the illustrated embodiment of the invention, the middle layer in the turbulence generator is the layer that is used as the regulation layer, in which the additional flow, preferably a water flow, and the flow of the pulp (M) having an average concentration coming out of the intermediate chamber 12 are combined. In such a case, the flow of regulated concentration is passed through the turbulence generator 13, and the flow, denoted now by Q.sub.4.1,Q.sub.4.2,. . . , Q.sub.4.n joins, in the vertical direction, the other, non-regulated flows of the pulp (M) coming out of the other tubes in the turbulence generator. At each position across the width of the web, the middle layer operates as the layer that regulates the grammage of the web.

The headbox in accordance with the invention is regulated so that, during operation, the grammage is regulated expressly by means of regulation of the additional subcomponent flows Q.sub.1.1,Q.sub.1.2, . . . , Q.sub.1.n. Thus, during running, the profile bar is not displaced and the systems of control and monitoring of the profile bar K are not required to be maintained. If there is a profile bar K, it is used just at the beginning of the run for advance regulation of the fiber orientation. The profile bar is thus almost never used for regulation of the grammage. The profile bar K comprises adjusting spindles with infrequent spacing and manual operation.

The additional component flow Q.sub.1 is preferably a flow that contains water alone or a so-called 0-water flow. The additional flow Q.sub.1 may also be a pulp flow whose concentration differs, on the whole, from the average concentration of the pulp suspension in the headbox and, thus, from the concentration of the component flow Q.sub.3.

FIG. 1C is a sectional view taken along the line I--I in FIG. 1A. Each additional-flow duct 20a.sub.1,20a.sub.2, . . . , preferably a pipe, comprises a valve 21a.sub.1,21a.sub.2, . . . , in which case it is possible, in the direction of width of the paper machine, to adjust the desired mixing ratio for the flows Q.sub.4.1,Q.sub.4.2, . . . , Q.sub.4.n each position of width, which flow, as it comes out of the turbulence generator 13 out of its turbulence tube 13a.sub.1,13a.sub.2, . . . , acts further as a regulation flow at the desired location of width of the pulp suspension jet.

FIG. 1D is a sectional view taken along the line II--II in FIG. 1A. Out of the diluting inlet header 19, the diluting liquid, preferably diluting water, is passed into the ducts 20a.sub.1,20a.sub.2 . . . , and by means of the valve 21a.sub.1,21a.sub.2 . . . placed in each duct, preferably a pipe, the diluting flow is regulated by throttling the flow in accordance with the regulation of the valve.

FIG. 1E is a sectional view of the attenuation chamber 17 shown in FIG. 1A. As shown in FIG. 1E, the attenuation chamber 17 extends across the entire machine width.

FIG. 2A is an enlarged illustration of the embodiment shown in FIG. 1B. From the intermediate chamber 12, a flow Q.sub.3.1 passes into the mixing chamber 130 in the turbulence tube 13a.sub.3.1 of the turbulence generator 13. Into the mixing chamber, a flow duct 20a.sub.1 is provided for the diluting flow. In the embodiment of FIG. 2A, the flow duct joins the mixing chamber halfway in relation to the length of the mixing chamber. The sectional flow area of the mixing chamber 130 in the direction of the flow S (arrow S) is A.sub.1, and this area is substantially larger than the sectional flow area A.sub.2 of the duct portion 131 following after the mixing chamber in the turbulence tube in the turbulence generator.

FIG. 2B is a sectional view taken along the line IV--IV in FIG. 2A.

FIG. 3 shows a second preferred embodiment of the construction related to the mixing chamber. A flange piece 1320 comprises a flow duct 132. The flow duct 132 comprises a straight duct portion 132a.sub.1 having a circular section and therein a sectional flow area A.sub.3 and a conically widening duct portion 132a.sub.2, which is connected with walls 130' of the mixing chamber 130. The flow duct 132 is placed between the intermediate chamber 12 and the mixing chamber 130. The sectional flow area A.sub.3 is substantially smaller than the sectional flow area A.sub.3 of the mixing chamber 130. The flange piece 1320 is connected, by means of a press fitting or a threaded joint, with the recess f.sub.1 that has been made into the face of the frame 13R of the turbulence generator 13 defined by the intermediate chamber 12. Also in this embodiment, the mixing chamber 130 is followed by a duct portion 131 in the turbulence tube, whose sectional flow area is substantially smaller than the sectional flow area of the mixing chamber 130.

FIG. 4A shows an embodiment related to the mixing chamber, wherein a pipe or duct 133 extends from the intermediate chamber 12 into the mixing chamber 130. The pipe 133 extends into the mixing chamber 130 so that the pipe is opened in the end of the mixing chamber 130 and is placed centrally on the central axis X.sub.1 of the mixing chamber 130. The flow Q.sub.3 from the intermediate chamber 12 enters through the pipe 133 into the mixing chamber 130. On its outer face 133', the pipe 133 comprises a throttle flange 133d, preferably an annular flange, which projects from the outer face and by whose means the diluting flow Q.sub.1 is throttled. The annular flange 133d is placed on the circular circumference of the pipe 133. The diluting flow Q.sub.1 is passed into the space between the pipe 133 face 133' and the mixing-chamber 130 face 1301, as shown in FIG. 4, along two diluting ducts 20a.sub.1 ',20a.sub.1. It is understood that there may be just one diluting-flow duct. In view of considerations of space, it is possible to use two ducts in the way shown in FIG. 4. Also, the pipe 133 comprises a flange 133c, preferably an annular flange, at its end, by means of which flange the pipe is connected with a recess f.sub.2 in the frame 13R of the turbulence generator. The joint is accomplished either by means of a press fitting or by means of a threaded joint. It can also be accomplished by gluing. The front face of the flange 133c is placed facing the intermediate chamber 12.

FIG. 4B is a sectional view taken along the line V--V in FIG. 4A. The flow Q.sub.1 out of the additional-flow duct 20a.sub.1 passes annularly to the end of the pipe 133 bypassing the flange 133d of the pipe. The flows Q.sub.3 and Q.sub.1 are combined in the mixing chamber 130 at the end of the pipe 133.

FIG. 5A shows the headbox of a paper/board machine in accordance with the invention, which headbox comprises, proceeding in the flow direction S of the pulp suspension M, an inlet header 10, a distribution manifold 11, an intermediate chamber, i.e., in the present case, a mixing chamber 12, a turbulence generator 13, which comprises a number of turbulence tubes 13a.sub.1.1,13a.sub.2.1, . . . ,13a.sub.1.2, 13a.sub.2.2, . . . placed side by side and one above the other, and a discharge duct 14, into which the turbulence tubes 13a.sub.1.1,13a.sub.2.1, . . . , 13a.sub.1.2, 13a.sub.2.2, . . . of the turbulence generator 13 are opened. The discharge duct 14 is defined by a stationary lower-lip wall 15 and by an upper-lip wall 16 pivoting around an articulated joint. In the following, when the invention is described and when a paper machine is spoken of, it is obvious that a board machine and its headbox may also be concerned.

In the construction as shown in FIG. 5A, the intermediate chamber 12 has been divided or partitioned, in the direction of width of the headbox of the paper machine (in the transverse direction), into a number of zones or blocks 12a.sub.1,12a.sub.2, . . . ,12a.sub.n placed side by side. Each block 12a.sub.1,12a.sub.2, . . . ,12a.sub.n is connected with a respective additional-flow duct 20a.sub.1, 20a.sub.2, . . . , 20a.sub.n, preferably a 0-water duct and preferably a pipe. Each flow duct 20a.sub.1,20a.sub.2, . . . ,20a.sub.n comprises a valve 21a.sub.1,21a.sub.2, . . . ,21a.sub.n, by whose means the throttle of the additional component flow Q.sub.1 and, thus, its velocity and the flow quantity that is passed into the intermediate chamber 12, into its zone 12a.sub.1,12a.sub.2, . . . ,12a.sub.n concerned at each particular time are regulated.

Each zone 12a.sub.1,12a.sub.2, . . . ,12a.sub.n is connected with a respective distribution pipe 11a.sub.1,11a.sub.2, . . . of the distribution manifold 11. From the inlet header 10, a pulp flow of average concentration is passed through the distribution pipe 11a.sub.1,11a.sub.2, . . . into the intermediate chamber 12 of the headbox of the paper machine, into the various zones 12a.sub.1, 12a.sub.2, . . . ,12a.sub.n in the chamber 12. Each additional subcomponent flow Q.sub.1 is introduced through the duct 20a.sub.1,20a.sub.2, . . . ,20a.sub.n at a high velocity, whereby it is mixed in the zones 12a.sub.1,12a.sub.2, . . . ,12a.sub.n in the intermediate chamber 12 efficiently with the pulp component flow Q.sub.3. Out of the zones 12a.sub.1,12a.sub.2, . . . ,12a.sub.n the mixed component flow Q.sub.4 is passed into the turbulence generator 13 into the turbulence tubes 13a.sub.1, 13a.sub.2, 13a.sub.3, . . . ,13a.sub.n in its upper row.

In the mixing chamber 12, each mixing zone 12a.sub.1,12a.sub.2, . . . ,12a.sub.n has been arranged as a compartment in the direction of width of the headbox so that each zone 12a.sub.1,12a.sub.2, . .. ,12a.sub.n is separate and does not communicate with the adjacent zone. Moreover, from each zone 12a.sub.1, 12a.sub.2, . . . ,12a.sub.n, an overflow 22a.sub.1,22a.sub.2, . . . ,22a.sub.n has been arranged into the attenuation chamber 17. The overflows 22a.sub.1,22a.sub.2, . . . ,22a.sub.n have a common air space 23. Each overflow has been formed preferably from a space fitted above the zones 12a.sub.1,12a.sub.2, . . . in the intermediate chamber 12, which space comprises an air space common of the overflows 22a.sub.1, 22a.sub.2, . . . and separate overflow thresholds 180a.sub.1,180a.sub.2, . . . for each overflow. Each overflow space is defined in relation to the adjacent spaces by means of partition walls 170a.sub.1,170a.sub.2, . . . Thus, in accordance with the invention, by regulating the height of the overflow threshold 180a.sub.1,180a.sub.2, . . . , it is possible to regulate the pressure that prevails in the zone 12a.sub.1, 12a.sub.2, . . . in the intermediate chamber 12, and in this way, by regulating the position of the overflow threshold, it is possible to regulate the flow quantity of the flow Q.sub.4 departing from the compartments 12a.sub.1,12a.sub.2, . . . The overflows are opened into a common exhaust duct E.sub.1.

When the additional component flow Q.sub.1 is introduced along the duct 20a.sub.1,20a.sub.2, . . . into the pulp suspension component flow Q.sub.3 of the average concentration of the headbox, the exhaust flow is produced as an overflow component Q.sub.2. In such a case, the mixed flow Q.sub.4 passed into and out of the turbulence generator 13 has a quantity equal to the component flow Q.sub.3 coming out of the distribution tube 11a.sub.1,11a.sub.2, . . . Thus, when the mixing ratio is regulated by bringing the additional component flow Q.sub.1 into the component flow Q.sub.3 along the duct 20a.sub.1,20a.sub.2, . . . the flow quantity Q.sub.4 passing into the turbulence tube 13a.sub.1,13a.sub.2 of the turbulence generator 13 is kept invariable and constant. The quantity of the overflow Q.sub.2 is equal to the quantity of the additional component flow Q.sub.1 that was introduced.

The additional component flow Q.sub.1 is preferably a flow consisting of water alone, i.e. a so-called 0-water flow. The additional component flow Q.sub.1 may also be a pulp flow whose concentration differs, on the whole, from the average concentration of the pulp suspension in the headbox and, thus, from the concentration of the component flow Q.sub.3.

FIG. 5B is a sectional view taken along the line VI--VI in FIG. 5A. As shown in FIG. 5B, each overflow zone or block 12a.sub.1,12a.sub.2, . . . is defined by partition walls 170a.sub.1,170a.sub.2, . . . The overflows of the zones 12a.sub.1,12a.sub.2, . . . are opened into the common outlet E placed at the other side of the overflow threshold 180. Each additional-flow duct 20a.sub.1,20a.sub.2, . . . comprises a valve 21a.sub.1,21a.sub.2, . . . , in which case it is possible, in the direction of width of the paper machine, to adjust the desired mixing ratio for the subflows Q.sub.4.1, Q.sub.4.2, . . . , Q.sub.4.n, of the combined total headbox pulp flow, at each location of width, which flow, as it comes out of the turbulence generator 13 out of its turbulence tube 13a.sub.1,13a.sub.2, . . . acts further as a regulation flow at the desired location of width of the pulp suspension jet. The zones or blocks 12a.sub.1,12a.sub.2, . . . ,12a.sub.n may be formed so that, at each location of width, the walls 170a.sub.2, 170a.sub.3 extend vertically from the lower part of the intermediate chamber in the headbox to its upper part and further into the overflow space, where they divide each overflow space into blocks at the zone of that location of width. The zones 12a.sub.1,12a.sub.2, . . . ,12a.sub.n may also have been formed so that they comprise a bottom part D. In this case the blocks or zones 12a.sub.1,12a.sub.2, . . . ,12a.sub.n have been formed into the intermediate chamber 12 of the headbox of the paper machine at each location of width in same and so that the blocks are placed in the upper part of the intermediate chamber 12 and are defined by the walls 170a.sub.2, 170a.sub.3 and by the bottom part D.

FIG. 5C is an axonometric illustration in part of the arrangement in blocks of the headbox of a paper machine in the direction of width as illustrated above in order to permit regulation of the consistency and the fiber orientation of the pulp suspension at the desired location of width independently from one another.

FIG. 6A is an illustration of principle of the headbox of a paper machine, which headbox is in the other respects similar to the embodiment shown in FIGS. 5A, 5B and 5C, except that the arrangement in compartments has been carried out by means of pipe connections. For regulation of the quantity subflows Q.sub.4.1, Q.sub.4.2, a respective valve 24a.sub.1,24a.sub.2 is arranged in each overflow pipe 220a.sub.1, 220a.sub.2, . . . In the embodiment of FIG. 6A, each additional subcomponent flow Q.sub.1.1,Q.sub.1.2, . . . ,Q.sub.1.n is passed from the inlet header 25, being regulated by the valves 21a.sub.1,21a.sub.2, . . . placed in the additional-flow pipes 20a.sub.1,20a.sub.2, . . . . directly into the distribution tube 11a.sub.1,11a.sub.2, . . . in the distribution manifold 11. The respective distribution tubes 11a.sub.1,11a.sub.2, . . . pass further into a separate pipes 26a.sub.1,26a.sub.2, . . . placed in the intermediate chamber 12, which pipes 26a.sub.1,26a.sub.2, . . . are connected with an overflow pipe 220a.sub.1,220a.sub.2, . . . The overflow pipe 220a.sub.1,220a.sub.2, . . . is opened into an attenuation chamber 17 which comprises a collecting chamber 28 common of the overflows 220a.sub.1,220a.sub.2 . . . , a common air space 23, a common overflow threshold 29, and a common outlet E.

FIG. 6B is a sectional view taken along the line VII--VII in FIG. 6A. The individual pipes 26a.sub.1,26a.sub.2, . . . arranged in the intermediate chamber 12 prevent mixing of the combined component flow Q.sub.3 +Q.sub.1 with the rest of the pulp flow in the intermediate chamber 12.

FIG. 6C is a sectional view taken along the line VIII--VIII in FIG. 6A.

FIG. 7A shows an embodiment of the invention in which the flow quantity Q.sub.4 is regulated by means of valves 31a.sub.1,31a.sub.2, . . . ,31a.sub.n, which are placed in respective turbulence tubes 13a.sub.1,13a.sub.2, . . . adjacent to one another in the direction of width in the upper row in the turbulence generator 13.

FIG. 7B is a sectional view taken along the line IX--IX in FIG. 7A.

The examples provided above are not meant to be exclusive. Many other variations of the present invention would be obvious to those skilled in the art, and are contemplated to be within the scope of the appended claims.

Claims

1. A method for regulating a total pulp flow from a headbox, said headbox comprising a pulp inlet header, a discharge duct and conduit means for passing the total headbox pulp flow from said inlet header to said discharge duct, said conduit means including a plurality of conduits, said total headbox pulp flow comprising at least one component flow, the method comprising the steps of:

forming said at least one component flow from component subflows arranged at different locations in a direction transverse to a direction of flow of at least one component flow,

forming each of said component subflows from at least first and second subcomponent flows,

directing each of said second subcomponent flows from said inlet header into a respective one of said conduits,

introducing each of said first subcomponent flows into one of said second subcomponent flows at a point within one of said conduits at a certain mixing ratio, said introducing step comprising the steps of arranging a mixing chamber in each of said conduits, passing one of said second subcomponent flows through a separate pipe arranged in each of said mixing chambers, passing a respective one of said first subcomponent flows annularly from around said pipe into an end of the respective one of said mixing chambers, and

regulating the concentration of each of said subflows by adjusting the flow rates of said first subcomponent flow and said second subcomponent flow, which constitute said subflow, relative to one another.

2. The method of claim 1, further comprising the steps of:

arranging said conduits in a transverse direction of said headbox, and

passing each of said first subcomponent flows into one of said conduits.

3. The method of claim 1, further comprising the step of:

throttling each of said first subcomponent flows by means of a valve to vary the rate of flow of each of said first subcomponent flows into a respective one of said second subcomponent flows.

4. The method of claim 1, wherein said second subcomponent flows comprise a pulp flow, further comprising the steps of:

providing said second subcomponent flows with a concentration corresponding to an average concentration of pulp suspension in said headbox, and

providing said first subcomponent flows as a water flow.

5. The method of claim 1, further comprising the step of passing said first subcomponent flows from an additional inlet header into a respective one of additional-flow pipes arranged in different locations in the transverse direction of said headbox.

6. The method of claim 1, further comprising the step of:

fluidly coupling said mixing chamber to said inlet header, and

passing said subflow constituting a combination of one of said first subcomponent flows and one of said second subcomponent flows from said mixing chamber into a first duct portion of the respective one of said conduits, said first duct portion having a sectional flow area smaller than the sectional flow area of said mixing chamber.

7. The method of claim 6, further comprising the step of passing each of said second subcomponent flows from said inlet header into said mixing chamber through a second duct portion of a respective one of said conduits, said second duct portion having a sectional flow area substantially smaller than the sectional flow area of said mixing chamber.

8. The method of claim 1, wherein said first subcomponent flows are a diluting flow and each of said conduits has a first duct portion arranged after said mixing chamber in the pulp flow direction, said first duct portion having a sectional flow area smaller than the sectional flow area of said mixing chamber,

further comprising the step of passing said subflow thus formed from said at least one of said first component flows and said one of said second component flows to said discharge duct.

9. The method of claim 8, further comprising the steps of:

arranging a flange on an outlet end of said pipe opening into said mixing chamber, said flange projecting from a face plane of said pipe, and

throttling said first subcomponent flows by means of said flange before each of said first subcomponent flows is mixed with the respective one of said second subcomponent flows.

10. The method of claim 1, further comprising the step of regulating the grammage of a web formed from said total headbox pulp flow only by regulating said first subcomponent flows.

11. The method of claim 1, further comprising the steps of:

throttling each of said first subcomponent flows by means of a valve to reduce or increase the rate of flow of each of said first subcomponent flows into a respective one of said second subcomponent flows,

passing said at least one of said component flows into said discharge duct,

prior to passing said at least one of said component flows to said discharge duct, removing as overflow a portion of said at least one of said component flows after said first and second subcomponent flows have been combined, whereby if the combined flow rate of said first and second subcomponent flows is increased based on an increase in the flow rate of said first subcomponent flow, the excess amount is removed as overflow so that the rate of flow of said at least one of said component flows into said discharge duct remains constant.

12. The method of claim 1, wherein said conduits constitute turbulence tubes of a turbulence generator, said conduit means further including a distributor manifold coupled to and arranged after said inlet header in a flow direction of the pulp, means defining an intermediate chamber, said distributor manifold having distribution pipes opening into said intermediate chamber, means defining an attenuation chamber arranged in connection with said intermediate chamber, said turbulence generator being arranged after said intermediate chamber in the pulp flow direction, inlet ends of said turbulence tubes opening into said intermediate chamber, further comprising the steps of:

passing each of said first subcomponent flows directly into a respective one of said distribution pipes in said distribution manifold, and

passing each of said first subcomponent flows from said distribution pipes through a pipe in said intermediate chamber and into a respective one of said conduits.

13. A method for regulating a total pulp flow from a headbox, comprising a pulp inlet header, a discharge duct and conduit means for passing the total headbox pulp flow from said inlet header to said discharge duct, said conduit means including a plurality of conduits, said total headbox pulp flow comprising at least one component flow, the method comprising the steps of:

forming said at least one component flow from component subflows arranged at different locations in a direction transverse to a direction of flow of said at least one component flow,

forming each of said component subflows from at least first and second subcomponent flows,

directing each of said second subcomponent flows from said inlet header into a respective one of said conduits,

introducing each of said first subcomponent flows into one of said second subcomponent flows at a point within one of said conduits at a certain mixing ratio, said introducing step comprising the steps of passing at least one of said first subcomponent flows into a mixing chamber in at least one of said conduits, coupling said mixing chamber to said inlet header, and passing said subflow constituting a combination of said at least one of said first subcomponent flows and one of said second subcomponent flows from said mixing chamber into a first duct portion of said at least one of said conduits having a sectional flow area smaller than the sectional flow area of said mixing chamber, and

regulating the concentration of each of said subflows by adjusting the flow rates of said first subcomponent flow and said second subcomponent flow which constitute said subflow relative to one another.

14. A method for regulating a total pulp flow from a headbox, said headbox comprising a pulp inlet header, a discharge duct, and conduit means for passing the total headbox pulp flow from said inlet header to said discharge duct, said conduit means including a plurality of conduits, said total headbox pulp flow comprising a plurality of component flows, the method comprising the steps of:

forming each of said plurality of component flows from component subflows arranged at different locations in a direction transverse to a direction of flow of said component flow,

forming a plurality of said component subflows from at least first and second subcomponent flows,

directing each of said second subcomponent flows from said inlet header into a respective one of said conduits,

introducing said first subcomponent flows into said second subcomponent flows within said conduits, said introducing step comprising the steps of arranging mixing chambers in said conduits, passing each of said second subcomponent flows through a respective pipe arranged in one of said mixing chambers, passing one of said first subcomponent flows annularly from around said pipe into an end of each of said mixing chambers, and

regulating the concentration of each of said subflows by adjusting the flow rates of said first subcomponent flow and said second subcomponent flow, which constitute said subflow, relative to one another.

15. A method for regulating a total pulp flow from a headbox, comprising a pulp inlet header, a discharge duct, and conduit means for passing the total headbox pulp flow from said inlet header to said discharge duct, said conduit means including a plurality of conduits, said total headbox pulp flow comprising a plurality of component flows, the method comprising the steps of:

forming each of said plurality of component flows from component subflows arranged at different locations in a direction transverse to a direction of flow of said component flow,

forming a plurality of said component subflows from at least first and second subcomponent flows,

directing each of said second subcomponent flows from said inlet header into a respective one of said conduits,

introducing said first subcomponent flows into said second subcomponent flows within said conduits, said introducing step comprising the steps of passing one of said first subcomponent flows into a mixing chamber in one of said conduits, coupling said mixing chamber to said inlet header, and passing said subflow formed in said mixing chamber from said mixing chamber into a first duct portion of said one of said conduits having a sectional flow area smaller than the sectional flow area of said mixing chamber, and

regulating the concentration of each of said subflows by adjusting the flow rates of said first subcomponent flow and said second subcomponent flow which constitute said subflow relative to one another.

16. In a headbox comprising a pulp inlet header, a discharge duct and conduit means for passing a total headbox pulp flow from said inlet header to said discharge duct, said conduit means including a plurality of conduits, said total headbox pulp flow comprising at least one component flow having component subflows in a transverse direction of said headbox, the improvement comprising;

a device for regulating the flow of said at least one component flow through said conduit means, said device comprising

means for forming component subflows of said at least one component flow arranged at different locations in a direction transverse to a direction of flow of said at least one component flow, each of said component subflows being formed from at least first and second subcomponent flows,

means for regulating the flow of each of said first subcomponent flows relative to the flow of a respective one of said second subcomponent flows to thereby regulate the concentration of said component subflows and thus said at least one component flow so as to adjust the grammage of a web formed from said total headbox pulp flow to a desired level in the transverse direction, said regulation means comprising;

means for passing each of said second subcomponent flow from said inlet header to a respective one of said conduits,

additional-flow duct means for directing each of said first subcomponent flows into one of said second subcomponent flows within one of said conduits, said additional-flow duct means communicating with a respective one of said conduits such that said first subcomponent flows are carried into different positions in the transverse direction of said at least one component flow,

means for regulating the flow of said first subcomponent flows through said additional-flow duct means, and

means defining a mixing chamber arranged in each of said conduits, said additional-flow duct means being connected to said mixing chambers.

17. The device of claim 16, wherein said additional-flow duct means comprise valves which regulate the flow resistance and rate of flow of each of said first subcomponent flows.

18. The device of claim 16, wherein at least one of said tubes comprises

a first duct portion arranged after said mixing chamber in the pulp flow direction, and

a second duct portion following said first duct portion in the pulp flow direction, said second duct portion having a sectional flow area which is substantially smaller than the sectional flow area of said first duct portion.

19. The device of claim 16, wherein at least one of said conduits comprises a flow duct portion arranged between said mixing chamber and said inlet header, said flow duct portion having a smaller sectional flow area in comparison with the sectional flow area of said mixing chamber.

20. The device of claim 16, further comprising a flange piece having a throttle-duct portion arranged in at least one of said conduits, said flange piece being mounted by a threaded joint or a press fitting at a mouth of said at least one conduit.

21. The device of claim 20, wherein said throttle piece comprises at least two duct portions, a first one of said duct portions comprising a straight duct portion having a constant sectional flow area and a second one of said duct portions comprising a conically widening duct portion connected to said mixing chamber.

22. The device of claim 16, further comprising an annular pipe in flow communication between said mixing chamber and said inlet header, said annular pipe being arranged in relation to said mixing chamber such that each of said first subcomponent flows is passed annularly between an outer face of said mixing chamber and said pipe into a mixing point placed at an end of said pipe and being combined at said mixing point with a respective one of said second subcomponent flows.

23. In a headbox comprising a pulp inlet header, a discharge duct and conduit means for passing a total headbox pulp flow from said inlet header to said discharge duct, said conduit means including a plurality of conduits, said total headbox pulp flow comprising a plurality of component flows having component subflows in a transverse direction, the improvement comprising;

a device for regulating the flow of said component flows through said conduit means, said device comprising

means for forming component subflows of each of said component flows arranged at different locations in a direction transverse to a direction of flow of said component flow, a plurality of said component subflows being formed from at least first and second subcomponent flows,

means for regulating the concentration of each of said plurality of said component subflows formed from said first and second component subflows and thus said component flows so as to adjust the grammage of a web formed from said total headbox pulp flow to a desired level in the transverse direction, said regulating means comprising;

means for passing each of said second subcomponent flows from said inlet header to a respective one of said conduits,

additional-flow duct means for directing said first subcomponent flows into said second subcomponent flows within said conduits, said additional-flow duct means communicating with said conduits,

means for regulating the flow of said first subcomponent flows through said additional-flow duct means, and

means defining a mixing chamber in each of said conduits, said additional-flow duct means being connected to said mixing chambers.