KR100467358B1 - An arrangement for feeding stock to a headbox in a papermaking machine - Google Patents

Abstract

An arrangement (2) for feeding stock to a headbox (1) in a papermaking machine, which comprises at least one stock header (3) with an inlet for receiving stock into the header and a plurality of stock header outlets (5) permitting stock to leave the header. For each stock header outlet (5) there is a stock conduit (7, 8, 9) downstream of the stock header outlet permitting stock to pass from the stock header outlet (5), through the conduit (7, 8, 9) to the inlet of the headbox. The arrangement includes a dilution header (30) for feeding a diluent such as water to a plurality of stock conduits. The dilution header has an inlet (31) for receiving a diluent into the dilution header (30) and a plurality of outlets (32) permitting the diluent to leave the dilution header. For each dilution header outlet (32), there is a diluent conduit (33) permitting the passage of a diluent from the dilution header (30) into a stock conduit (7, 8, 9). According to the invention, the diluent is fed into a stock conduit (7, 8, 9) at a location immediately downstream of a stock header outlet (5) and the stock header together with the stock header outlets (5) is designed such that the velocity of the stock flowing through the stock header (3a, 3b, 3c) is substantially equal to the velocity of the stock in an upstream end (10, 11, 12) of the stock conduits (7, 8, 9).

Description

Device for feeding paper to head of paper machine {AN ARRANGEMENT FOR FEEDING STOCK TO A HEADBOX IN A PAPERMAKING MACHINE}

Inlet for receiving the stock of the present invention into the header (header), at least one paper header having a plurality of outlets to allow the paper to be discharged from the header, the stock of the inlet end of the headbox through the conduit at the outlet of the paper header Paper conduit suitable for each paper header outlet, such as tubular parts connecting the outlet of the header and the inlet end of the header box to pass through, and the outlet of the header and the inlet end of the head box to supply the diluent to the plurality of paper conduits. A dilution header having an inlet to receive the diluent into the dilution header, a dilution header having an outlet to allow the dilution to exit the dilution header, and the diluent through the dilution conduit at the dilution header outlet and the stock from the outlet of the media header to the inlet of the headbox. The paper head of the paper machine containing the diluent conduit which is to be passed through any of the paper conduits to be passed. It relates to a device for feeding in.

In the paper industry, the stock is discharged from the headbox through the slice lip to the forming wire. In the forming wire, water is drained from the stock and the web is formed in the wire. The feedstock is fed to the headbox from an upstream feedhead that carries the feedstock to the headbox at high pressure. When the stock is fed into the paper machine's headbox, the stock is usually arranged in a straight line extending laterally in the machine and connected to the inlet of the headbox at many evenly spaced connections, leading to the headbox inlet. From the headbox. In this way, the paper stock discharged from the headbox is distributed evenly across the machine to ensure that the paper web produced by the paper machine has uniform properties across the web width, such as basis weight and fiber orientation. The feedstock supplied to the headbox is uniformly distributed in the machine transverse direction.

However, during the papermaking process, inadequateness due to physical phenomena as well as the construction of the paper machine results in a failure to uniformly achieve the characteristics across the web and the paper web produced has non-uniformity across the web width. In order to correct such nonuniformity, it is generally performed to correct the amount of paper discharged from the headbox in the transverse direction of the machine. A known method of achieving this is to employ locally adjustable slice lips in the headbox. By changing the opening of the slice lip in the machine transverse direction, it is possible to adjust the amount of paper discharged from the headbox in the machine transverse direction. However, this method of controlling the stock discharged from the headbox causes the crossovers to affect the basis weight and fiber orientation when the stock flow changes at a point across the slice lip. There are disadvantages. In order to overcome this problem, it has been proposed that the stock fed to the headbox can be selectively diluted in such a way that the diluent is fed into at least a few conduits through which the stock is fed into the headbox. By adjusting the amount of diluent supplied to each conduit, the basis weight change can be corrected in the machine transverse direction. Apparatuses for selectively diluting feedstock to headboxes are described in US Pat. No. 5,196,091 (Hught) and US Pat. No. 4,897,158 (Wesshu et al.).

When such a device is used, the stock stream merges and mixes with the diluent stream at the confluence of each stream so that the stock stream and the diluent stream are mixed into the dilution stream at the total flow rate and the total amount of the diluted stock merges with each other. It is the sum of the flow rates. That is, Q _tot = Q _s + Q _d . Where Q _s is the stock flow, Q _d is the flow of the diluent, and Q _tot is the total flow of the stock diluted at the downstream of the confluence.

Since the stock in each conduit is not expected to be diluted to the same range, it is most important to feed the stock to the stock so that it does not affect the total flow rate of the stock or paper diluted downstream of the point where each flow meets. If the total flow rate of the diluent paper reaching the slice lip is not uniform in the transverse direction of the machine, this creates a transverse flow that affects the fiber orientation. Thus, when the diluent is supplied to the stock while moving to the slice gap, the flow rate of the diluent supplied into the stock flow stream is such that the flow of the dilution paper is equal to the flow rate at each stock conduit downstream of the point where the diluent is fed to the stock. Regardless, it has been found that a method should be used to ensure that the total flow rate of the diluent is kept constant in the stock conduit.

A solution to the above mentioned problem is described in US Pat. No. 5,316,383 (Begemann et al.). According to this document, the first flow rate of liquid (ie stock) entering through the first inlet line is combined with the second flow rate of liquid (ie diluent such as water or diluent) flowing through the second inlet line. By mixing. The two liquids are mixed with each other at the confluence point to form the total flow rate of the mixed liquid. The first inlet line is arranged at a mixing angle with respect to the second inlet line and the mixing angle is selected such that the total flow rate of the mixed liquid is kept constant. According to this document, the solution to this problem depends on the proper choice of mixing angle. The preferred mixing angle of the first embodiment is described as 80 degrees. This document also describes other mixing angle experiments demonstrating that increasing the second flow rate at a mixing angle of 90 ° results in a decrease in the total flow rate of the mixed liquid.

Another solution to the problem of achieving a uniform flow rate of the mixed liquid is described in the above mentioned Hergert '091 patent. According to this document, the headbox device is provided with a tapered inlet or paper header to suit the paper flow. The upstream end of the tube bank with multiple tubes suitable for the stock flow is connected to the taper inlet so that the stock flows through the taper inlet and from the inlet through the upstream end of the tube bank to the downstream end of the tube bank. . Multiple feed conduits for diluents, such as fresh or white water, are connected to the upstream end of the tube bank. Each feed conduit has a distal end disposed very closely upstream and upstream with respect to the upstream tube of the tubebank. In Figure 6 of the '091 patent, the distal end of the feed conduit is shown positioned on the wall of the tapered inlet so that the feed conduit feeds the diluent directly to the stock at the upstream end of the tube upstream end in the tube bank. According to the '091 patent, when a diluent such as water flows through the distal end to the stock, the stock flowing through the tube adjacent the distal end is diluted but the flow ratio through the tube does not change. In this case, the constant flow ratio is due to the fact that the diluent is fed upstream of the stock of the tube.

Each of the above-mentioned can be provided to dilute the stock flowing through the tube without affecting the total flow rate of the stock through the tube. However, known solutions are not always satisfactory. For example, the solution in accordance with the '091 patent provides that the diluent can be fed to the stock very precisely if the diluent is fed directly to the taper inlet or the stock header at an upstream end of the tube where it may not reach the tube end exactly. It entails no potential risks. Moreover, feeding the diluent directly to the stock header can result in a change in the pressure in the header that can affect the flow of the stock conduit. The solution according to the '383 patent requires a design that connects the inlet lines of each fluid because the fluids must meet each other at the correct angle and the oblique connection required from a manufacturing standpoint is not the simplest designed. In addition, experiments conducted by the inventors of the present invention did not confirm that the mixing angle claimed in the '383 patent is very important.

Thus, a solution that is easily applied to the problem of feeding the diluent flow into the stock flow so that the change in the diluent flow does not affect the total flow of the diluent feed, while the stock flow and the diluent flow form the total flow of the diluent feed. This is necessary. In addition, there is a need for a paper dilution device that is simple to manufacture. In addition, there is a need for a paper dilution apparatus that ensures good mixing of the stock and diluent.

In addition, there is a need for a device that supplies paper stock to the headbox that can be easily installed under various conditions.

Summary of the Invention

The first object of the invention is to provide a diluent flow so that the change in diluent flow rate does not affect the total flow rate of the diluent paper in the apparatus for feeding the feedstock to the headbox, while the paper flow rate and the diluent flow rate form the total flow rate of the diluent paper. It is to achieve an easily applicable solution to the problem of feeding the feed stock. A first object of the present invention is achieved by an apparatus for supplying the stock of the present invention to the head box of a paper machine. The apparatus includes at least one stock header having a stock feed to the inlet end of the headbox and an inlet receiving the stock into the stock header and a plurality of outlets through which the stock exits the header. For each paper header exit, there is a paper conduit downstream of the paper header outlet, which allows the paper to pass from the paper header exit through the conduit to the inlet end of the headbox, whereby the outlet of the paper header at the inlet end of the headbox. Is connected. The apparatus supplies a diluent to a plurality of stock conduits connecting the outlet of the stock header to the inlet end of the headbox, further comprising a dilution header having an inlet for receiving the diluent into the dilution header and an outlet for allowing the diluent to exit the dilution header. Include. The diluent can be water, fresh water, or diluent, for example. For each dilution header outlet, there is a dilution conduit that allows the diluent to pass through the dilution conduit in the dilution header to any one of a plurality of media conduits downstream of the media header. Each dilution conduit has an upstream end connected to the outlet of the dilution header and a downstream end connected to either stock conduit to guide the diluent to the stock conduit. The downstream end of each diluent conduit according to the invention is either at the upstream end of the stock conduit and in the vicinity adjacent to the downstream of the paper header exit or otherwise at a position slightly downstream or adjacent downstream of the paper header exit and downstream of the paper header exit. It is connected to the paper conduit. Thereby, the diluent can be fed to the stock at a distance slightly adjacent or adjacent to the downstream location of the stock header outlet and downstream of the stock header outlet. The paper header exit is also designed in such a way that the speed of the paper at the upstream end of the paper conduit is substantially the same as the speed of the paper at the paper header.

The inventors found that the change performance of the diluent flow, in which the distance between the stock conduit and the diluent conduit and the media header outlet, affects the total flow rate of the diluent feed downstream of the connection between the diluent conduit and the stock conduit, is very important. . The relationship between the diluent flow change performance and this distance causing a change in the total flow rate of the diluent stock will be discussed.

When the stock passes through the stock conduit downstream of the stock header outlet, pressure losses occur due to the friction of the conduit. The greater the distance between the stock conduit and the diluent conduit and the stock header outlet, the greater the pressure loss before the diluent is fed to the stock. Many pressure drops result in a large pressure difference between the point of the paper conduit where the diluent is fed to the stock and the outlet of the stock header. When a diluent flow rate is supplied to the stock conduit, it tends to affect the stock conduit pressure. If different dilution conduits are expected to supply different amounts of diluent to the associated stock conduit, the individual stock conduit pressures are affected to a different extent than the pressure of the neighboring stock conduits. As a result, the flow rate downstream of the connection between the diluent conduit and the stock conduit is not the same as all stock conduits.

However, when the distance between the connection between the diluent conduit and the paper conduit and the paper header outlet is small, the pressure loss is small so that the pressure of the paper conduit is almost equal to the pressure of the paper header itself at the position where the diluent is supplied to the paper. It has been found that the diluent supply to the conduit has a minimal effect on the pressure of the stock conduit. As a result, the dilution paper flow rate downstream of the connection between the dilution conduit and the stock conduit is affected to a minimum and the flow rate of the dilution paper remains substantially constant despite the amount of change in the diluent flowing into the stock conduit. The smaller the pressure drop and distance between the connection between the conduits and the outlet of the stock header, the smaller the amount of change in the diluent supplied to the stock that can produce a change in the dilution stock flow rate through the stock conduit. In theory, the distance is preferably an approximation of zero or zero, which corresponds to the absence of pressure loss at all points between the connection between the diluent conduit and the stock conduit and the stock header outlet. In practice, however, there is an arbitrary distance between the connection between the diluent conduit and the stock conduit and the stock header outlet. However, the inventors have found that when the pressure of the stock header is about 300 kPa, this distance does not exceed 0.15 meters corresponding to the pressure loss of 1 kPa or more. The term "directly downstream of" should not be understood in the context of this application to mean that there is no distance at all points between the connection between the diluent conduit and the stock conduit and the stock header exit.

According to the invention, the feed rate at the upstream end of the feed conduit is substantially the same as the feed rate of the feed header itself. For the upstream end of the paper conduit, the paper header is tapered so that the cross section of the paper header decreases in the paper flow direction of the paper header, and the upstream end of the paper conduit and the diameter of the paper header outlet are the cross-sectional area of the upstream end of the paper conduit and the paper header exit. The cross sectional area is chosen to be equal to the reduction of the cross section of the header header between the two media header outlets. In other words, the difference in paper header cross-sectional area between two paper header outlets is equal to the cross-sectional area of each paper header outlet and the cross-sectional area of each paper conduit upstream end. When the static pressure of the paper header is substantially the same at both ends of the paper header, this dimensioning of the paper header tapering results in the speed of the paper at the upstream end of the paper conduit being substantially the same as the paper header. The inventors regard the diluent as a paper when the speed of the paper at the upstream end of the paper conduit is the same as the paper header, especially when the rate of feed of the paper conduit is the same as the paper header at the point where the diluent is supplied to the paper. It has been found that feeding has a relatively small effect on the total flow rate of the diluent stock so that a change in the diluent flow rate supplied at the feedstock produces a negligible change in the total flow rate of the diluent stock.

The stock conduit connected to the diluent conduit comprises a throttle valve to create a disturbance at a location downstream between the diluent conduit and the stock conduit whereby it is advantageous for the stock and the diluent to be properly mixed with each other. To further ensure good mixing of the stock and diluent, the stock conduit is given a length such that the frictional losses of the conduit will cause further disturbances.

The paper conduit preferably includes a flexible hose that allows the paper header to be located in many different positions relative to the headbox, thereby allowing the device to be installed more easily.

1 is a schematic side view of a headbox and a device for feeding stock to a headbox.

Figure 2 is a plan view of the head box and a part of the feed material shown in Figure 1;

Figure 3 is a cross section through the paper header showing the connection between the diluent conduit and the paper conduit, the paper header outlet and the paper header in more detail.

4 is a cross-sectional view taken along the line IV-IV of FIG.

FIG. 5 is a sectional view similar to FIG. 3 showing some of the parts shown in FIG. 3 in more detail; FIG.

Fig. 6 is a plan view showing in more detail some of the parts shown in Fig. 3;

1 and 2 show a headbox having a device for feeding the stock to the headbox. In general, the headbox indicated by 1 is supplied with the stock by the apparatus 2 for supplying the stock to the headbox. The apparatus for supplying the stock to the headbox includes at least one stock header (3a, 3b, 3c) for feeding the stock to the inlet end of the headbox. 1 shows the stock headers 3a, 3b, 3c of the apparatus for supplying the stock to the three-layer headbox. In this case, each stock header may be arranged to feed the stock only to any of the three-layer webs manufactured by a paper machine employing a three-layer headbox. Each stock header (3a, 3b, 3c) has a plurality of stock conduits (7, 8, 9) in which the inlet (4) receives the stock into the header and the stock is discharged from the header and connected to the stock header outlet (5). A stock header outlet 5 is provided to enter the upstream ends 10, 11, 12. The feed header outlet 5 is connected to the inlet end 6 of the headbox by conduits 7, 8, 9 downstream of the feed header outlet, so that the conduits 7, 8, 9 can feed the feed at the outlet of the feed header. Passes through the paper conduit to the end 6 of the head box 1, whereby the outlet 5 of the paper headers 3a, 3b, 3c is connected to the inlet end of the head box 1 so that the paper is It can pass from the headers 3a, 3b, 3c to the inlet end 6 of the headbox 1 via the stock conduits 7, 8, 9. Each stock conduit 7, 8, 9 has an upstream end 10, 11, 12 connected to the outlet header 5 of the stock header and a downstream end 14 suitable for connection or attachment to the inlet end 6 of the headbox. , 15, 16). The upstream end of each feed conduit has a standard feed flow direction intended to direct from the feed header outlet 5 to the inlet end 6 of the headbox and each upstream end 10,11 of the feed conduit 7, 8, 9; 12 has a cross-sectional area A ₃ perpendicular to the standard flow direction intended to pass through the upstream ends 10, 11, 12 of the stock conduits 7, 8, 9, and this cross-sectional area A ₃ is the paper header. It is equal to the cross-sectional area of the outlet 5. The conduits 7, 8, 9 comprise tubes or tubular parts 17, 18, 19 having an inner wall defining a channel for the stock or dilution paper passage. Each tube or tubular component 17, 18, 19 has an upstream end 20, 21, 22 and a downstream end 23, 24, 25. It is advantageous for both the tube or tubular part to be a flexible hose having a length of at least 2 m. All of the stock headers 3a, 3b, 3c are connected to the headbox 1 by flexible hoses 17, 18, 19, and the stock headers 3a, 3b, 3c are different in relation to the headbox 1. Ensures easy installation in multiple locations. Since the flexible hoses 17, 18 and 19 have a length of at least 2 m, significant pressure loss occurs while the diluent feeds through the flexible hose, which creates a turbulence that ensures good mixing of the data and the diluent. The lengths 17, 18 and 19 of the hoses contribute to the easy installation of the stock headers 3a, 3b and 3c in different positions with respect to the headbox 1. Referring to Figure 3, each stock conduit 7, 8, 9 includes a tubular coupling 26 at its upstream end, the tubular coupling 26 of the stock headers 3a, 3b, 3c. It has an upstream end connected to the outlet 5 and a downstream end 28 connected to the associated tubular parts 17, 18, 19. In Fig. 3, the tubular coupling 26 consists of three parts 26a, 26b and 26c as shown and the part 26a is located at an upstream end 27 of the tubular coupling 26. It is fixed between the outlet 5 of the header and the walls of the stock headers 3a, 3b, 3c. The component 26c is located at the downstream end 28 of the coupling 16 and connects the coupling 26 to the associated tubular components 17, 18, 19.

Component 26b may be used to connect to a downstream end of the conduit that supplies the diluent to the stock through the stock conduit. For the downstream end of the conduit, the intermediate coupling component 26b consists of a T-connection.

1 and 2, the dilution header 30 is shown. The dilution header 30 has an inlet 31 which receives the dilution liquid into the dilution header 30 and a plurality of outlets 32 which allow the dilution liquid to be discharged from the dilution header 30. The dilution header 30 is intended to supply the diluent to a plurality of stock conduits 7, 8, 9 which connect the outlets of the stock headers 3a, 3b, 3c to the inlet end 6 of the headbox. For each dilution header outlet 32, diluent is passed through the dilution conduit 33 at the dilution header outlet 32 into one of the downstream stock conduits 7, 8, 9 of the stock header 3a, 3b, 3c. And a diluent conduit 33 downstream of the dilution header outlet 32 which passes into the stock through the stock conduits 7, 8, 9. Each of the diluent conduits 33 comprises an upstream end 34 connected to the outlet 32 of the dilution header and a connection 26b at the upstream ends 10, 11, 12 of the stock conduits 7, 8, 9. It has a downstream end 35 connected to any one of the stock conduits 7, 8, 9. The connection is preferably in the form of a T-connection 26b. According to the present invention, the upstream ends 10, 11, 12 of the stock conduits 7, 8, 9 are located at a position immediately downstream of the outlet 5 associated with the associated stock conduit. Stock conduits (7, 8, 9), in the dilution header (30) via the dilution conduit (33) and immediately downstream of the stock header (3a, 3b, 3c) outlet (5). Can pass through. The term "immediately downstream of" does not mean that the distance between the stock conduit (7, 8, 9) and the diluent conduit and the stock header exit is necessarily zero in the context of this application. There is actually some distance between the connection and the media header outlet. However, this distance is kept as small as possible and does not exceed 0.15 m. The pressure loss occurring in the paper conduit between the paper header outlets 5 is kept low and does not exceed 1 kPa. At the pressure of the stock header 3 of about 300 kPa, the pressure at the point where the diluent is supplied to the stock conduits 7, 8, 9 is equal to the pressure of the stock headers 3a, 3b, 3c or slightly smaller by friction. As a result, the dilution flow variation does not affect the total flow rate of the dilution paper flowing through the stock conduits 7, 8, 9.

Referring to Figure 1, each diluent conduit 33 comprises a pipe 36 through which the diluent flows as intended, the pipe 36 upstream of the stock conduit and the upstream end 36a adjacent the outlet of the associated dilution header. A diluent can flow through the pipe into the stock animal through the stock conduit, including a downstream end 35 connected to the end to discharge the diluent. Diluent conduit 33 also includes valve means 37 upstream of pipe 36 and downstream of the associated dilution header outlet. The valve means 37 comprises a channel, through which the diluent is intended to flow from the dilution header into the pipe, the valve means forming a connection between the dilution header outlet and the pipe. By having a cross-sectional area in the valve means 37 which can change the channel in a known manner, the diluent flow rate flowing into the pipe through the valve means 37 can be varied as necessary. At this end there is an actuator 38 for each valve means 37, which actuates the diluent flow rate from the dilution header 3b to the stock conduit 8 by varying the cross-sectional area of the channel intended for the dilution to flow. Arranged to change. Each actuator 38 increases or decreases the diluent flow rate through the diluent conduit 8 in response to a signal from a central processing unit (not shown), such as a computer, and the signal is for example 39 in FIG. It is input to the actuator via a cable marked with. While the paper machine is in operation, there is a scanning device (not shown) that keeps track of the change in the transverse properties of the paper web at a position downstream of the headbox. If such a non-uniformity is found, a signal is sent to the central processing unit and the next central processing unit transmits the signal to one or more actuators. In response, actuator 38 acts to reduce or increase the diluent flow rate at one or more locations such that a paper web with uniform properties is achieved.

According to the invention, it is also important that the feed rate at the upstream end of the feed conduit is the same as the feed rate at the feed header. The inventors have found that the feed velocities flowing through the upstream ends 10, 11, 12 of each feed header outlet 5 and each feed conduit 7, 8, 9 are determined at the feed headers 3a, 3b, 3c. It was found that, at the same rate as the paper rate, the change in the flow rate of the diluent supplied to the paper flow rate would cause less change in the total flow rate of the dilution paper. Although this reason is not fully understood, the experiments and flow simulations performed by the inventors have established that this is true. Therefore, the apparatus for supplying the feedstock to the headbox has a feedstock velocity flowing through the feedhead outlet 5 and the upstream ends 10, 11, 12 of the feed conduits 7, 8, 9. It is designed to be equal to the paper speed of 3b and 3c).

3 and 6, the stock headers 3a, 3b, 3c have a length between the first end 40 and the second end 41 and between the first end 40 and the second end 41. The paper header inlet 4, which has an extension and allows the paper to enter the paper header from the paper pressurization source, is located at the first end 40 of the paper headers 3a, 3b, 3c. The recycle outlet 42 is located at the second end 41 of the paper header, which causes the paper to be discharged from the paper header and enters the recycle conduit through which approximately 5% of the paper is recycled. The recirculation conduit 43, located immediately adjacent to the recirculation outlet 42 or downstream inside the recirculation outlet, can be adjusted by controlling the positive pressure at the second end 41 of the stock headers 3a, 3b, 3c. There is a valve means 44. While the apparatus 2 for feeding the stock is in operation, the stock flows from the first end 40 of the stock header 3a, 3b, 3c to the second end 41 of the stock header, while all the stock headers. At the outlet 5, a portion of the stock is discharged from the header via the stock header outlet 5. Of course, the paper header outlets 5 are located in a row from the paper header first end to the paper header second end 41 and the paper header outlets 5 are spaced apart from each other at uniform intervals. Both paper header outlets have a cross-sectional area A ₃ and the cross-sectional area A ₃ is the same at all paper header outlets 5. Thus, the paper header is described as having a standard flow direction of the intended paper from the first end 40 of the paper header to the second end 41 of the paper header and the paper flowing through the paper header has any speed. The stock has a standard flow direction from the first end of the stock header 3a, 3b, 3c to the second end 41 of the stock header 3a, 3b, 3c. When the stock flows through the stock headers 3a, 3b, 3c, the method allows the speed of the stock to increase from the first end 40 of the stock header to the second end 41 of the stock headers 3a, 3b, 3c. To ensure that it remains substantially constant. This is accomplished by setting the recirculation valve means 44 in such a way that the static pressure at the second header 41 of the stock headers 3a, 3b, 3c is equal to the static pressure at the first header of the stock header. By using the Bernoulli equation, the pressure loss is equal at the first end 40 of the stock headers 3a, 3b, 3c and at the second end of the stock headers 3a, 3b, 3c and the pressure loss due to friction of the stock header. If this is negligibly small, it indicates that the speed of the stock does not change substantially between the first end 40 of the stock header and the second end 41 of the stock header.

Referring to Figure 6, the stock header has a cross-sectional area in a plane perpendicular to the standard flow direction of the stock intended to pass through the stock header. The stock headers 3a, 3b, 3c are tapered such that the cross-sectional area of the stock header decreases gradually from the first end 40 of the stock header to the second end 41 of the stock headers 3a, 3b, 3c. As shown in Figure 6, it has a first cross-sectional area A ₁ at the point where the stock header outlet 5 is located and a second cross-sectional area A2 at the next stock header outlet 5, the second cross-sectional area being It is smaller than the first cross-sectional area A1. The upstream ends 10, 11, 12 of each stock header outlet 5 and associated stock conduits 7, 8, 9 have a cross-sectional area A ₃ , and the cross-sectional area A ₃ has a stock conduit 7, 8. It is perpendicular to the standard stock flow direction passing through the upstream ends 10, 11, and 12 of (9). The tapering of the paper headers 3a, 3b, 3c from the paper header first end 40 to the second end 41 of the paper header along the length of the paper headers 3a, 3b, 3c is A _1- . A ₂ = A ₃ or so. That is, the cross section of the stock headers (3a, 3b, 3c) between two neighboring stock header outlets is reduced and the amount of reduction in cross-sectional area is equal to the cross-sectional area of each stock header outlet (5), which is the It is equal to the cross-sectional area of the upstream ends 10, 11 and 12.

By analyzing the flow rates of the stock headers 3a, 3b, 3c and the stock conduits 7, 8, 9, the second end 41 of the stock header at the first end 40 of the stock headers 3a, 3b, 3c. In the case of the feed velocity flowing at), the cross-section area of each feed header outlet 5 and the cross-section areas 10, 11, 12 of each feed conduit 7, 8, 9 are adjacent to each other. If the paper header cross-sectional area is equal to the difference between (5), the paper velocity flowing through the upstream ends 10, 11, 12 of each paper conduit (7, 8, 9) is the paper header (3a, 3b, 3c). It can be seen that flowing from the first end 40 of the paper header to the second end 41 of the paper header is substantially the same as the paper header paper speed. The term " same as " means that the paper velocity flowing through the paper headers 3a, 3b, 3c corresponds to the paper velocity flowing through the upstream ends 10, 11, 12 of the paper conduits 7, 8, 9; It should be noted that since it has a direction that is substantially perpendicular, it should be understood as meaning "same size".

In order for the flow rate of the diluent to be supplied into the stock flow rate in such a way that the change in the dilution flow size does not cause the final flow rate change of the dilution paper, the inventors firstly check that the diluent is directly downstream of the stock header outlet 5. The feed rate is fed into the feed at an adjacent position or downstream of the feed header outlet 5, and secondly, the feed speed at the upstream ends 10, 11, 12 of the feed conduit 7, 8, 9 is applied to the feed header 3a, It was found that the stock headers 3a, 3b, 3c should be designed to be substantially equal to the stock speeds of 3b, 3c. However, in a preferred embodiment of the present invention, the inventors believe that these two features are combined with each other, and that the combination of these features has a synergistic effect with each other, and the features reinforce each other.

When the diluent is fed into the stock animal, it is important that the diluent is properly mixed with the stock. As mentioned earlier, the length of the tubular parts 17, 18, 19 contributes to the achievement of good mixing between the two liquids. In addition, a coupling 26 connecting the stock headers 3a, 3b, 3c and the tubular components 17, 18, 19 downstream of the stock headers 3a, 3b, 3c is provided with a stock conduit (7, 8). A throttle valve 26d downstream of the connecting portion 26b connecting 9 to the diluent conduit 33. The throttle valve 26d causes disturbances in the flow of the diluent stock, thereby ensuring that the diluent mixes well with the stock. 3 and 5, the throttle valve 26d is located in the downstream coupling component 26c and forms part of the downstream coupling component. 5 shows in more detail the connection between the downstream end 35 of the diluent conduit 33 and the upstream ends 10, 11, 12 of the stock conduit. As shown in Fig. 5, the intermediate piece 26b of the coupling 26 is formed with a 90 ° T-connection so that the intermediate piece 26b passes through the length extension part and the intermediate piece 26b in a standard paper flow direction. An intermediate piece 26b includes a short tubular piece 26e that extends across the longitudinal axis of the intermediate piece 26b (from right to left in FIG. 5). As a result, the intermediate part 26b forms a connection portion between the downstream end 35 of the diluent conduit 33 and the upstream ends 10, 11, 12 of the stock conduits 7, 8, and 9.

In a preferred embodiment of the invention, the three stock headers 3a, 3b, 3c are adapted to feed the multilayer headbox 1 of the type designed to produce a fibrous web (not shown) having three layers. It is used to In this embodiment, each stock header (3a, 3b, 3c) with associated stock conduits (7, 8, 9) downstream of the stock header outlet (5) has only one of three layers of fibrous web. It is arranged to supply. The feedstock is thus fed only to the second intermediate layer of the fibrous web together with the associated stock conduit 8 and the first stock header 3a arranged to feed the feed only to the first upper layer of the fibrous web with the associated stock conduit 9. There is a third stock header 3c, arranged to supply the stock only to the third underlayer of the fibrous web, with a second stock header 3b and associated stock conduit 7 arranged to do so. In a preferred embodiment, the dilution header is arranged to feed the feed only to the stock conduit 8 which is connected to the second stock header 3b which is arranged to feed the feed only to the second intermediate layer of the fibrous web so that the dilution liquid is made of the fibrous web. Only the stock intended for the second intermediate layer is fed to the stock conduit 8 through which it passes. The cross-machine web properties can thus be adjusted by adjusting the concentration of stock intended for the middle layer of the web.

Since control of the web properties is only achieved by controlling the amount of diluent supplied to the stock intended for the second intermediate layer, a fine adjustment of the intermediate layer is made in the parts of the headbox 1 having a small expansion force in the machine transverse direction. It is important to be able. Thus, the tubular part 18 of the stock conduit 8 connected to the second stock header 3b arranged to feed the stock only to the second intermediate layer of the fibrous web is intended to be the first upper layer of the web and the third lower layer of the web. It is larger and smaller in diameter than the tubular parts of the stock conduits 7 and 9 connected to the first and third stock headers 3a and 3c arranged to supply the finished stock. 1, 3 and 4, the tubular components 17, 18, 19 of the stock conduits 7, 8, 9 connected to the outlet 5 of each stock header 3a, 3b, 3c have an inner diameter. Flexible hoses 17, 18 and 19 having an outer diameter and an outer diameter, wherein the first and third raw material headers 3a and 3c are arranged to feed the first and third layers of the fibrous web having the same inner and outer diameters. Paper conduit 8 connected to the flexible hoses 17 and 19 of the paper conduits 7 and 9 connected to the outlet and to the outlet 5 of the second paper header 3b arranged to feed the paper to the second layer of the fibrous web. All of the flexible hoses 18) have the same inner diameter and the same outer diameter. The inner diameter of the flexible hose 18 of the stock conduit 8 connected to the second stock header 3b arranged to feed the stock to the second layer of fibrous web is arranged to feed the stock to the first and third layers of the fibrous web. It is smaller than the inner diameter of the flexible hoses 17 and 19 of the stock conduits 7 and 9 connected to the first and third stock headers.

3 and 4, the downstream end of the flexible hoses 17, 18, 19 of the stock conduits 7, 8, 9 at the inlet end 6 of the headbox 1 is a connection point 45, 46. 47 is connected to the inlet end of the headbox. The connection points 45 of the downstream end of the flexible hose 19 of the stock conduit 9 of the first stock header 3a are arranged in a straight horizontal row extending in the machine transverse direction, so that the inlet end of the head box 1 ( In 6) the downstream end of the flexible hose 19 of the stock conduit 9 connected to the first stock header is arranged in a first straight row extending in the machine transverse direction. In the same way, the downstream end of the flexible hose 18 of the stock conduit 8 of the second stock header 3b is arranged in a straight horizontal row extending in the machine transverse direction, so that the inlet end 6 of the headbox 1 is arranged. At the downstream end of the flexible hose 18 of the stock conduit 8 connected to the second stock header 3b in a second straight row extending in the machine transverse direction. Similarly, the downstream end portions of the flexible hoses 17 of the stock conduit 7 of the third stock header 3c are arranged in a straight horizontal row arranged in the machine transverse direction so that the third stock at the inlet end 6 of the headbox 1 is arranged. The downstream end of the flexible hose 17 of the stock conduit 7 connected to the header 3c is arranged in a third straight row extending in the machine transverse direction. The first, second and third columns are located in a first row positioned vertically above the second row and the third row, a second row positioned perpendicular to the bottom of the first row, and positioned vertically below the first row and the second row. Spaced perpendicularly to each other in a third row.

As shown in Fig. 4, each of the first, second and third rows has a downstream end of the flexible hoses 17, 18 and 19 for each row in the transverse direction with the inlet end 6 of the headbox. Arranged to be spaced apart from each other. In each row, the downstream ends of the flexible hoses 17, 18, 19 are spaced apart from one another at even intervals. The spacing between the flexible hose 18 in the second row, ie, the downstream end of the flexible hose 18 through which the dilution feed passes, is smaller than the spacing between the downstream ends of the flexible hoses 17 and 19 in the first row and the third row. The smaller spacing between the downstream ends of the second row of flexible hoses 18 provides for fine adjustment of the stock concentration in the parts having a small extension in the machine transverse direction. In practice, the spacing between the flexible hose connection points in the second row is approximately 50-70 mm, and the inner diameter of the flexible hose is approximately 45 mm.

The present invention allows the flow rate of the diluent to be supplied into the stock flow rate so that the total flow rate of the dilution paper becomes constant despite the flow rate fluctuation of the diluent. Changes in the flow rate of the diluent do not result in changes in the total flow rate of the diluent stock. Components can be manufactured to some extent and the present invention can be readily applied to existing devices. The present invention also results in excellent mixing of the diluent and the stock. Moreover, the present invention facilitates the installation of a feeder for feedstock to the headbox, thanks to the long flexible hose used to connect the feedhead to the headbox, since the feedhead is located at different positions relative to the headbox.

Claims (11)

In the apparatus (2) for supplying a diluted paper stock to a paper machine, (a) feed the paper machine, having an inlet end 40 and an opposing recycle end 41, defining a header flow direction extending therebetween, Further defines a row of uniformly spaced outlets 5 each having a predetermined cross-sectional area for allowing the stock to flow from the headers 3a, 3b, 3c in a direction generally perpendicular to the header flow direction, The flow rate through the stock headers 3a, 3b, 3c is reduced by an amount equal to the cross-sectional area of each said outlet from each outlet 5 to an adjacent outlet in the header flow direction so that the flow rate through each of the outlets 5 is substantially the same. At least one stock header (3a, 3b, 3c) tapered to define a cross-sectional area; (b) a recycling conduit (43) connected to a recycling outlet (42) adjacent said recycling end (41) of said stock header (3a, 3b, 3c); (c) a recirculation valve (44) located at the recirculation outlet (42) for adjusting the static pressure of the recirculation end portion (41) of the stock header (3a, 3b, 3c); (d) each of said stock headers having upstream ends 10, 11, 12 connected to respective stock header outlets 5 and downstream ends 14, 15, 16 suitable for attachment to the inlet end of the paper machine. Connected to the outlet, Paper conduits (7, 8, 9) each having a predetermined internal cross-sectional area equal to the cross-sectional area of said connected paper header outlet (5); (e) a dilution header having an inlet 31 and a plurality of outlets 32 through which the diluent is discharged from the dilution header 30 and for supplying the diluent to at least one of the stock conduits 7, 8, 9. 30; And (f) a diluent is connected from each dilution header outlet 32 via a dilution conduit 32 to each of said dilution header outlets 32 to dilute the stock passing therethrough. , 8,9), A diluent conduit 33 having an upstream end 34 connected to each dilution header and a downstream end 35 connected to each stock conduit 7, 8, 9; Apparatus for supplying a diluted paper stock to a papermaking machine comprising a. The method of claim 1, Each diluent conduit 33 is connected to each stock conduit 7, 8, 9 at a predetermined location along the stock conduit, the location being the outlet 5 from the stock header 3a, 3b, 3c. And an adjacent downstream of about 0.15 meters or less. The method of claim 2, The diluent conduit (33) is characterized in that the stock conduit (at a location where the stock pressure of the stock conduits (7, 8, 9) is less than about 1 kilopascal less than the stock pressure at each of the stock header outlets (5). 7,8,9). In the apparatus (2) for supplying a diluted paper stock to a paper machine, (a) a plurality of spacings arranged in first, second and third rows extending in the cross-machine direction to produce a fibrous web with three layers and to receive the stock for each of the layers A multilayer headbox 1 defining defined openings 45, 46, 47, wherein the openings in the second row 46 are the distance between the respective openings 45, 47 in the first and third rows. Multi-layer head box (1) spaced below; (b) an inlet 40 for supplying a stock to said first row opening 45 of said multilayer headbox 1 to form a first, top layer of said fibrous web; ) And a first stock header (3a) having a plurality of outlets (5) through which the stock is discharged from the head (3a); (c) an opening in the headbox 1 and an upstream end 12 respectively connected to one of the first paper header outlets and connected to each paper header outlet 5 to allow paper to pass through the paper machine. A first set of stock conduits (9) each having a downstream end (16) constructed and aligned to be attached to a first row of said having a predetermined inner diameter; (d) feed the stock into the second row of openings 46 of the multilayer headbox 1 to form a second, intermediate layer of fibrous web, the inlet 40 for receiving the stock and the stock to the header A second stock header 3b having a plurality of outlets 5 to be discharged from 3b; (e) an upstream end 11 and the headbox 1 respectively connected to one of the second paper header outlets 5 and connected to each paper header outlet 5 so that paper material is delivered to the paper machine. A second set of stock conduits (8) each having a downstream end (15) constructed and aligned to attach to a second row of openings (46) and having a predetermined inner diameter; (f) Feeding the stock into the third row of the openings 47 of the multilayer headbox 1 so as to form the bottom layer of the third, fibrous web, the inlet 40 for receiving the stock and the stock having the header 3c. A third stock header (3c) having a plurality of outlets (5) for discharging therefrom; (g) an upstream end 10 and the headbox 1 respectively connected to one of the third stock header outlets 5 for feed to the paper machine and connected to each stock header outlet 5; Each having a downstream end 14 constructed and aligned to attach to a third row of openings 47 and having a predetermined inner diameter, the inner diameter of the second set of conduits 8 being the stock conduits 9 and 7 respectively. A third set of stock conduits (7) smaller than the inner diameter of said first and third sets of; (h) a dilution header 30 having at least a second set of feed conduits 8 and having an inlet 31 and a plurality of outlets 32 through which the diluent is discharged from the dilution header 30. ); And (i) at least the second set of said second dilution header outlets 32 from said respective dilution header outlets 32 through said dilution conduits 33 for diluting feedstock through and connected to each said dilution header outlet 32; Pass the diluent through one of the stock conduits (8), A diluent conduit 33 each having an upstream end 34 connected to each dilution header outlet 32 and a downstream end 35 connected to each stock conduit 8; Apparatus for supplying a diluted paper stock to a papermaking machine comprising a. The method of claim 4, wherein The stock conduit 8 is A flexible tubular element 18 having an upstream end 21 and an opposing downstream end 24 adjacent the stock header 3b, and an upstream end connected to each outlet 5 of each stock header 3b, 27) and a tubular coupling (26) each having a downstream end (28) connected to an upstream end of the flexible tubular element (18). 6. The tubular coupling (26) of claim 5, wherein each tubular coupling (26) has a downstream end (35) of said diluent conduit (23) when said stock passes through said tubular coupling (26). Device defining a lateral opening (in 26b) which is connected to allow the diluent to be supplied from the stock to the stock. The method of claim 6, Wherein said flexible tubular element has a length of about 2 meters. The dilution conduit (33) of claim 4, wherein (a) a pipe 36 through which the diluent passes and has an upstream end adjacent to each outlet 32 of the dilution header 30 and a downstream end connected to and discharged from an upstream end of each stock conduit 8; (b) a valve (37) connecting an upstream end of said pipe (36) to an outlet of said dilution header (30) and defining a channel having a variable cross-sectional area through which diluent passes; And (c) an actuator (38) operatively connected to the valve (37) for changing the cross-sectional area of the channel to change the flow from the dilution header (30); Apparatus comprising a. The method of claim 6, Each said tubular coupling (26) further comprises a throttle valve (26d) downstream of the lateral opening (26b) via which diluent passes as it passes into said coupling (26). 5. The device according to claim 4, wherein the diluent conduit (33) is connected to the stock conduit (8) at a position no greater than about 0.15 meters from the outlet (5) of the stock header (3b). 5. The diluent conduit (33) according to claim 4, wherein the diluent conduit (33) is characterized in that the stock conduit (at 8) connected to the device.