FI109300B - Feeding arrangement for the pulp in a paper or cardboard machine - Google Patents

Description

i 109300 j Paper or board machine pulp feed arrangement

The invention relates to a pulp feeding arrangement for a paper or board machine according to the preamble of claim 1.

The conventional pulp feed arrangement of a paper or board machine comprises each particle stock container from which the part mass is pumped to the particle dispensing container 10 or directly to the particle mixing container. From the metering tank, the bulk mass is fed by a pump and metered by a valve into a common channel that leads to the mixing tank for the bulk mass.

j From the mixing tank, the pulp is pumped into the machine tank. From the machine tank, the pulp is pumped for short rotation through a speed control or a weight control valve. There is usually overflow from the machine tank back to the mixing tank. Dilution of the pulp occurs in use-15 steps. First, the mass is diluted at the bottom of the storage tank to about 4-5% consistency if it is at about 10-14% consistency at the top of the storage tank. Second, the pulp is diluted in the passage between the storage tank and the metering tank so that the consistency in the metering tank is about 3.5%. In addition, the dosing tank has a powerful mix to even out the consistency.

I. Third, the pulp is diluted in the passage between the mixing tank and the machine container, such that the consistency in the machine container is about 3%. At this consistency, the thick pulp is then fed into a short cycle, i.e. a wire well in a short cycle. In the wire well, the thick mass is diluted to about 1% headbox consistency.

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It · · ',,, · The mixing tank and machine tank form a mass equalization unit and dilute the mass to the final dispensing consistency. In addition, they ensure uniform dispensing of the machine mass' * '' ·. The mixing tank always aims to maintain a constant level.

: In traditional mix tank and machine tank solutions, several successive

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: Level adjustments can cause problems because the leveled tank outlet. ; ·. When 30 flows change by one unit, the inlet flow must change by two. ·,: Units in order for the level to return to the desired level. The control chain becomes long and this in turn causes vibrations in the mass flows. The oscillations, in turn, cause 2,109,300 problems in consistency and flow control, which results in varying machine stock weights.

FI patent 103676 discloses a newer processor arrangement of a short cycle 5 of a paper or board machine. In this process arrangement marketed under the OptiFeed ™ brand, the mixing tank, machine tank and wire well are eliminated. The viscous particles are dosed from the dosing tank to a closed mixing volume, where the particles are mixed and diluted in a dilution water flow to a consistency of about 1.5%. From this closed mixing volume, the pulp is fed to the 10 headboxes in a closed space through purification steps and, if necessary, venting. From the closed mixing volume in the line leading to the headbox, the mass is further diluted to about 1.0% headbox consistency.

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Fl patent 104384 discloses an apparatus for mixing fresh pulp and tap water derived from a wire well. The apparatus comprises a first pipe passing from the machine tank through the return water tank 15 and extending to the lower part of the wire well. The apparatus further comprises a second pipe extending from the return water tank to the bottom of the wire well. The first pipe is led from the return water tank forward centrally within the second pipe. The first tube extends slightly further into the wire well than the second tube. The pipe ends .. · .: A mixing point is formed at the connection. At least the periphery of the inner and / or outer surface h '· 20 of the wall of the first tube is wavy at the point of mixing. This kind of rigidity provides ':' *: effective fresh pulp. mixing of return water and tap water.

One problem with prior art paper or board machine viscous pulp feed systems is the interruptions in the pulp flow range from 2 sec to 2 min. These interruptions may be consistency failures due, for example, to the obstruction of a stock pulp stock.

'* High-consistency mass pieces detached from the inner surface of the stock atom cause spikes in the consistency of the mass atom. Also, the pulp fed to the pulp atom exhibits consistency fluctuations that cause consistency fluctuations in the stock. The malfunctions may also be refinement fluctuations due to fluctuations in the degree of refining of the pulp fed to the storage tomato. In addition, disturbances may be caused by variations in the filler content of the wreck removed and re-introduced: ',, *. This wreck, recovered from the process, is led to a warehouse tom from where it is re-fed to the process. Also, there are fluctuations in the filler content in the pulp recovered in the disc 109300. The pulp to be recovered in the disk filter is also led to a storage tomato, from where it is re-fed to the process.

5 For purposes of this application, viscous pulp feedrates refer to pulp feedrates between fractional storage towers and short rotation. In short cycle, the consistency of the pulp is generally greater than 2%.

The object of the invention is to provide a thick pulp feed system for a paper or board machine in which disturbances in the pulp flow in the range of 2 s to 1 min are attenuated before the pulp is fed into a short circulation. When the disturbances in the viscous mass flow are suppressed in the above area, the variations in the basis weight of the machine mass due to the consistency changes of the machine mass are also reduced.

The pulp feed system 1y11e of the paper or board machine according to the invention is essentially characterized by what is set forth in the dark mark portion of claim 1.

In the pulp feeding arrangement of a paper or board machine according to the invention is placed. at least one damping device for the mass fraction between the stock atom and the short rotation mass.

t · '; "· The pulp feeding arrangement of the paper or board machine according to the invention can be applied to all types of paper or board machines.

The following describes some of the feed arrangements for the pulp * * of a paper or board machine according to the invention with reference to the figures in the accompanying drawings, in which the invention is described in detail.

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However, ... * is not intended to be limited solely.

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Fig. 1 schematically shows a paper or board machine according to the invention ». ·: ·. 30 mass feed arrangement in which the damping device is disposed in a stock tomato of each partial mass. 'And between the particle dispensing container and / or the machine container and the wire well.

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Figure 2 schematically illustrates another pulp feeder arrangement of a paper or board machine according to the invention, wherein the damping device replaces the mixing and machine container.

Figure 3 schematically illustrates a third pulp feeder arrangement of a paper or board machine 5 according to the invention, wherein the damping device is disposed between a metering container and a closed mixing volume.

Figure 4 is a schematic top plan view of a damping device suitable for the rigid arrangement according to the invention.

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Fig. 5 is a cross-sectional view of the mixing point of the attenuator shown in Fig. 4.

Figure 6 is a schematic top plan view of an alternative damping device suitable for the arrangement of invention 15.

Fig. 7 is a schematic view of how a short-period disturbance in a mass flow is attenuated by a damping device according to the invention.

Fig. 1 schematically illustrates a conventional pulp feeder for a paper or board machine with mixing 12 and machine container 14 and '·' · wire well 120. Each of the '' 'parts is fed from its own storage tower 8A, 8B, 8C by means of stock pump feeding pumps * '' 9A, 9B, 9C to the particle dispensing container 10A, 10B, 10C.

'... · 10B, 10C each part mass is supplied to the mixing tank 12 by means of dosing pumps 1A, 11B, 11C. From the mixing tank 12, the mass is fed by a mixing pump 13 to the machine tank 14.

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From the machine tank 1.4, the fresh mass Mj is fed by the machine tank pump to the lower ··· 'portion of the 15 wire wells. From the well 120, the pulp is fed by the wire well pump 121 through the vortex cleaner 122 ·, · j to the air vent 111. The air from the hopper 111 is fed through the headbox • ,,, · the feed pump 109 through the machine screen 110 to , · The fibrous tap water is recovered and fed to the wire well 120 and the venting vessel 111 has an overflow to the lower portion of the wire well 120.

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In the lower part of the wire well 120, the freshest mass Mp and the overflow of the deaeration tank 111 are mixed together and diluted with tap water to a headbox consistency (about 1%). The mixing principle described in the aforementioned FI patent 104384 can be applied. In the vortex cleaner 122, sand and other heavy and large (greater than 20 µm) impurities are removed from the pulp. In the deaeration tank 111, air is removed from the pulp by the vacuum and the air entrained in the pulp. Machine screen 110 forms the final cleaning step before the pulp is fed to headbox 106.

10 For each partial mass of the stock tomato 8a; 8B, 8C After the feed pump 9A, 9B, 9C, a damping device 20A, 20B, 20C according to the invention is disposed in front of the metering reservoir 10A, 10B, 10C of each partial mass. A similar damping device 20 is also located downstream of the machine tank pump 15. Such a damping device 20, 20A, 20B, 20C can attenuate disturbances in the mass flow over a period of time ranging from 2 seconds to 2 minutes. Attenuator 15 20, 20A. 20B, 20C will be described in more detail with reference to Figures 4-6.

In Figure 1, the portion of the pulp feed arrangement associated with the short ban LK is indicated by a dashed line. From the storage tanks 8A, 8B. 8C from a pulp feed system leading to a wire well 120! ·: The arrangement is referred to herein as the thick mass arrangement.

Figure 2 shows another pulp supply arrangement according to the invention. which differs from '*' · * in the feed sequence shown in Figure 1 for the mixing tank and machine tank. Figure 2 does not show the storage atoms 8A, 8B, 8C (Fig. 1) and dosing containers 10A. 10B. 10C, the mass feeding portion, which may be similar to that shown in Figure 1. In the feeding arrangement of Figure 2, the mixing tank and the machine tank are replaced by a damping device 20.

'* Is supplied from its own metering tank 10A, 10B, 10C to metering pumps 11A. 1 IB, 11C

• * ··. ”To the damping device 20, where the partial masses are mixed and the flow is stabilized. Alternatively After the dressing device 20, the fresh pulp is fed to the lower part of the wire well 120, as in the embodiment shown in Figure 1. The short rotation LK corresponds to that shown in Fig. 1 and is also indicated here by a dashed line.

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Figure 3 shows a mass feed arrangement marketed under the OptiFeed ™ brand. wherein the mixing and machine container and the wire well are eliminated. Figure 3 also does not show the storage atoms 8A, 8B, 8C (Fig. 1) and the dispensing containers 10A, 10B. 10C, which may be similar to that shown in Figure 1. In the arrangement of Figure 3, the partial masses are fed from the ammoising tanks 10A, 10B, 10C to the closed mixing volume 100 of the 1A, 11B, 11C agitation pumps, where From a closed mixing volume 100, the pulp is fed through a main line first feed pump 101 to a suction side of the screened 102 and vortex cleaning 103 to a main line second feed pump 104, where the pulp is diluted with dilution water flow from air 10 to 111. Thereafter, the pulp diluted to headbox consistency is fed to the headbox 106 by a second feed line 104 of the main line through a machine screen 105. ' Here, a dilution head box 106 is used and the dilution water flow is supplied from the deaeration tank 111 by a dilution water pump 130 through a screen 131. The tap water collected from the forming section 107 is fed by the wire 15 water pump 108 to the deaeration tank 111.

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Each dosing pump 1A, 11B. After 11C is placed a damping device 20A, 20B, 20C according to the invention. capable of attenuating interferences in the range of 2 to 2 minutes for each particle mass flow. Partial masses can also be introduced into a single attenuator, but three times the volume of the attenuator is required. In this case, all the partial masses are led to this common damping device where the partial masses are mixed together. The mass is then led to a closed mixing volume 100, where the mass is mixed and diluted in a dilution water stream. Mute. The device 20A, 20B, 20C will be described in more detail with reference to Figures 4-6.

Fig. 3 is a dashed line showing the portion of the pulp supply system associated with the short cycle LK.

Figure 4 is a schematic top view of a damping device 20, 20A, 20B, 20C used in the pulp feed arrangement 30 of the invention and Figure 5 is a cross-sectional view of the damping device shown in Figure 3. The damping device comprises an inlet duct 21, a delay loop duct 22 and an outlet duct 23. 23.

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As shown in Figs. 4 and 5, the incoming lumen 21 opens centrally to the delay loop channel 22 such that the flow direction of the mass flowing from the outlet of the inlet channel 21 to the delay loop channel 22 is substantially tangential to the wall of the delay loop channel 22. The outlet duct 23 consists of two legs 23a, 23b such that the first leg 23a of the en-10 opens to the top of the delay loop duct 22 and the second branch 23b j opens to the lower portion of the delay loop duct 22. The opening points of the legs 23a, 23b are opposed so that a line connecting the centers of the cross-sections of the opening points passes through the center of the cross-section of the delay loop channel 22. The branches 23a, 23b of the outlet channel 23 combine at some distance into a single outlet channel 23. Here, the first branch 23a of the outlet channel 15 is longer than the second branch 23b. The mass flow through the longer branch 23a is delayed more than the mass flow through the shorter branch 23b. The branches 23a. At the junction 23b, the interferences in the mass of each branch 23a, 23b are at a different stage, whereby they are offset at said junction.

The delay loop channel 22 shown in Figure 4 is circular.

Fig. 6 is a schematic top view of an alternative damping device 20 for use in a mass feeding arrangement according to the invention, which differs from the damping device shown in Fig. 3 with respect to the shape of the delay loop channel 22. Here, The inner wall of the inlet 1 channel 21 is further provided with fluidizing means 24 for fluidising the pulp inlet stream. The outlet port 21 of the inlet channel 21 has a mixing valve 25 which can:: enhance the mixing of the mass fed from the inlet channel 21 into the delay loop 11 The inner wall of the delay loop channel 22, in turn, is provided at a distance 30 from the discharge opening of the inlet channel 21 with mixing means 26 for further agitation in the delay loop channel 22.

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Instead of, or in addition to, passive mixing means, an active external energy mixing device, e.g. a propeller type mixing device, may be disposed in the delay loop channel 22. A propeller-type mixing device also brings pump-break energy into the mass flow.

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In the embodiments shown in the figures, the delay loop channel 22 has a substantially circular cross-section, so that it has good flow properties. However, this is not essential to the invention, but the cross-section of the delay loop channel 22 may be of any shape.

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The portion of the inlet channel 21 extending to the delay loop 22 can apply the mixing principle described in the above-mentioned U.S. Patent 104384. The inner and / or outer surface> of the space channel 21, or at least a portion thereof, is then undulated. Such an arrangement can facilitate the mixing of the mass fed from the inlet channel 21 and the mas-15 circulating in the delay loop 22. Also, the inner surface of the delay loop channel 22 may be wavy at some distance from the discharge opening of the inlet channel 22 and downstream thereof.

. ' Figure 7 is a schematic illustration of how a silent: 20 intermittent interference in a mass reference is attenuated by the attenuation device of the invention. The curve 1) illustrates the short-term interference in the mass flow and the curve 2) illustrates the attenuation of this interference - ';' * · * as a function of time with the damping apparatus according to the invention. The curve 3), in turn, illustrates': '' · attenuation of the interference in the case where the discharge channel 23 is composed of two different lengths. · Branch 23a, 23b.

In Figure 1, the damping device of the invention is disposed in a feed line for each fraction prior to a 20A, 20B, 20C metering container 10A, 10B, 10C and in a feed line prior to 20 wire wells 120. In the thickening feed system according to the invention, , 20A, 20B, 20C are at least one between the storage site 8A, 30 8B, 8C and the short lc, but they can also be located in multiple locations; as is the case in Figure 1.

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The damping device 20 used in the pulp feed arrangement of the invention is dimensioned such that the cross-sectional area of the delay loop channel 22 is at least 5 times larger than the cross-sectional area of the inlet channel 21. The cross-sectional area of the outlet channel 23 is in turn equal to the cross-sectional area 5 of the inlet channel 21. In the case where the initial portion of the outlet channel 23 consists of two legs 23a, 23b, the combined surface area of these legs is equal to the cross-sectional area of the inlet channel 21.

Delay loop 22 can achieve smaller delays than the tank because the tank 10 requires a certain minimum volume to control the surface height. If the delay loop 22 is dimensioned for a delay of, for example, 1 minute and the mass flow is 300 l / s, the volume of the delay loop 22 becomes 18 nT. 3, in which the damping device 20A, 20B. 20C is placed in the feed line for each particle mass, the volume of delay loop 22 can be dropped to an average of one third, i.e., 6 nT.

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The claims which follow, within the scope of the inventive idea as defined, may vary from the above only by way of example.

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Claims (11)

A pulp feeding arrangement in a paper or cardboard machine, which arrangement comprises thick pulp feeding and a short circulation (LK), characterized in that the pulp feeding arrangement comprises at least one damping device (20,20A, 20B, 20C). ) located on a section for feeding pulp between storage bodies (8A, 8B, 8C) for sub-masses and the coita circulation (LK), wherein the thick mass is circulated in a delay loop (22) of the damping device for damping disturbances in the area 2 s - 2 min in the mass flow before the thick mass is measured to the short circulation (LK). A pulp feeding arrangement according to claim 1, which arrangement in the direction of the pulp feeding comprises storage compartments (8A, 8B, 8C) for sub-masses and, thereafter, dosing containers (10A, 10B, 10C) for sub-masses, from each sub-mass 15 dosed into a mixing container (12) in which the sub-masses are mixed, a machine container (14) which together with the mixing container (12) forms a unit for leveling the pulp, a wire well (120), in which the mass in the machine container (14) is diluted with wire water: from the wire portion (107) to the inlet slab thickness and from which the mass is measured *; via cleaning means (122) to a lifting container (111) and thence further via cleaning devices (110) to the inlet carriage (106), characterized in that on the line for feeding pulp between the machine container ( 14) and the wire well (120) is additionally located: a damping device (20) comprising a delay loop (22) in which the mass flow is circulated for damping interference within the range of 2 seconds to 2 minutes. in this. »»> I t '; ': 25 3. Pulp feeding arrangement according to claim 1, which arrangement in the direction '; * 'for the feeding of the pulp comprises storage compartments (8A, 8B, 8C) for sub-masses and thereafter', M 'following dosing containers (10A, 10B, 10C) for sub-masses, from which each sub-mass * * · is dosed into a mixing plant ( 20), a wire well (120) in which the pulp in a machine container (14) is diluted with wire water collected from the wire portion (107) to the inlet leather thickness and from which the mass is measured via purification devices (122) to a vent container (111). and thence further via purifying means (110) to the inlet carriage (106), characterized in that the mixing plant is formed by a damping device 109300 (20) comprising a delay loop (22) in which the sub-masses are mixed and in which the mass flow is circulated for damping the area 2 s - 2 min in this. A pulp feeding arrangement according to claim 1, comprising arrangement in the direction 5 for the pulp feeding comprising storage compartments (8A, 8B, 8C) for sub-masses and subsequently the following dosing containers (10A, 10B, 10C) for sub-masses, from each of each sub-mass. is dosed into a closed mixing volume (100), in which the sub-masses are mixed and diluted with wirewater collected from the wire portion (107), and from which the mass is measured via purification means (122) to a vent container (111) and thence further via purifying devices (102,103) to the inlet carriage (106), characterized in that on the line for feeding sub-mass with each dosing container (10A, 10B, 10C) and the closed mixing volume (100) there is furthermore located a damping device (20A, 20B). 20C), which comprises a delay loop (22) in which the mass flow is circulated to attenuate interference within the range of 2 s - 2 min therein. 15 5. A thick pulp feeding arrangement according to any of claims 1-4, characterized in that a damping device (10A, 10B, 10C) is disposed between each storage compartment (8A, 8B, 8C) and each dosing container (10A, 10B, 10C). 20A, 20B, 20C), comprising a delay loop (22) in which the mass flow is circulated to attenuate disturbances within the range of 2 seconds to 2 minutes therein. Feeding arrangement according to any of claims 1-5, characterized in that the damping device (20A, 20B, 20C) comprises a delay loop (22) and an inlet channel (21) and an outlet channel (20). 23), wherein the area of the cross-section of the delay loop (22) is at least 5 times larger than the area of the cross-section of the inlet channel ► »·; The area (21), which in turn is equal to the area of the cross-section of the outlet channel (23), is the inlet through which the inlet channel (21) is inserted into the delay loop (22). the mass circulates at least 5 times in the delay loop (22) before leaving the delay loop (22) by mediating the outlet tube (23). ·: ·! 30 Feeding arrangement according to claim 6, characterized in that the delay loop (22) is formed by a circular channel to the cross-section, the inlet channel (21) is formed by a tube to the cross-section extending a bit into the delay loop (22). in that the direction of the mass flow which flows centrally into the delay loop (22) through the outlet opening of the inlet channel (21) is substantially tangential in relation to the delay loop (22) and the outlet channel (23) is formed by a tube section 5 in the wall of the delay loop (22). Feeding arrangement according to claim 7, characterized in that a section in the bending surface of the outlet channel (23) is formed by at least two branches (23a, 23b), which open into the wall of the delay loop (22) on opposite sides of the inlet channel (21). 10 Feeding arrangement according to claim 7 or 8, characterized in that the peripheral line of the inner and / or outer surface of the at least that portion of the inlet channel (21) extending into the delay loop (22) is road-shaped. through the outflow opening of the inlet channel (21) in the delay loop (22), the mass flow flowing in the delay loop (22) is effected. Feeding arrangement according to any one of claims 6-9, characterized in that on. in the inner surface of the delay loop (22), there is spaced from the outlet opening of: the inlet channel (21) located in the delay loop (22) mixing element 20 (26) with which the mixing of it through the outlet opening (22) of the inlet channel; One (21) flowing mass flow in the mass flow circulating in the delay loop (22) is effected. 11. A pulp feeding arrangement according to claim 1, characterized in that the thickness of the thickness of the pulp is at least 2%. I l «»> »i · t J I # · I I> * * I t» I