FI110796B - Method of removing air from a paper machine's wirewater container and corresponding wirewater container - Google Patents

Description

110796

A method for removing air from a paper machine tap water tank and a corresponding tap water tank

The invention relates to a method for removing air from a tap water tank of a papermaking machine 5 formed by a cylindrical vessel, an inlet chute connected to the upper part of the cylindrical vessel and an outlet connection connected to the lower part for tap water. The invention also relates to a tap water tank for carrying out the process.

In papermaking, the wire section removes considerable amounts of water, commonly referred to as tap water, from the web. The aim is to drain the wire water as smoothly as possible from the wire section by means of open ridges to the tap water tank so that the foam forming air cannot be mixed with the tap water. The tap water inlet-15 is known to be a high cylindrical vessel, from which the tap water is recirculated from below, whereby the downward flow is slow and any air bubbles can rise to the surface and exit the tap water. From the wire water tank, the tap water is led through a mixing pump to the desired 20 paper application. A tap water tank is also called a wire well.

As paper machine speeds continue to increase, the current drainage capacity of existing wire water tanks has become inadequate. First, as speeds increase, more air will bind to the tap water. In addition, the high machine speed also affects the drainage of the tap water. In this case, the flow of tap water in the gorges may be turbulent and the tap water -. * · *. I can commit more air. Similarly, fast flowing tap water causes harmful tap water, ···. eddies that interfere with air exhaust. In this case, increasing the venting capacity with current technology would require an increase in the tap water tank. However, this is not desirable, as the tap water tank and chutes already require a lot of installation: ·: **: 35 space on the paper machine's already tight side. On the other hand, there is a constant effort to reduce the volume of the tap water tank and, at the same time, the entire volume of the short circulation, in order to speed up the conversion of the production process.

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Excessive pulp content in the pulp causes many problems in the papermaking process. Pressure pulses, variations in consistency and flocculation of fibers, proliferation of aerobic microbes and algae, and fouling of various components are some of the pre-5 problems of excessive air content in the pulp. In addition, air bubbles can cause holes in the paper. For these reasons, among other things, the importance of deaeration in a short rotation of a paper machine cannot be underestimated.

The object of the invention is to provide a novel method and a tap water tank carrying out the method for short circulation of a paper machine in which the movement of the tap water energy: utilization of the tap water is enhanced. Characteristic features of the process of the present invention are apparent from the appended claim 1 and features of the inventive tap water tank according to claim 3. The inventive tap water tank utilizes a novel form and a method of importing tap water. In addition, a dewatering means is provided in the tap water tank to enhance the dewatering of the wire water tank according to the invention and its drainage from the tap water tank. When using the wire water tank and the venting device according to the invention, most of the air and other bubbles in the bubble-like state have been effectively removed from the tap water, thereby simplifying the process as a whole.

The invention will now be described in detail with reference to, ···. the accompanying drawings illustrating the invention, in which Figure 1 shows the layout of a tap water tank according to the invention on a paper machine as a schematic drawing,

Fig. 2a is a side elevational view, partly in section, of a tap water tank according to the invention.

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Figure 2b shows a top view of a tap water tank 35 according to the invention, partially in cross-section.

'* Figure 1 shows in principle the positioning of the tap water tank according to the invention on a paper machine. The arrangement of the invention relates to the wire section 10 of a paper machine, and in particular to the treatment of tap water in the tap water tank 13. In this context, a paper machine also means a board machine or the like.

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In web forming, headstock 11 feeds the pulp diluted to the desired consistency onto the wire portion 10. The wire portion 10 of Figure 1 has two web forming wires 12 and 12 'between which the pulp is fed. In practice, most of the highly aqueous pulp on the wire portion 10 is discharged as the tap water while the fibers and fillers continue as web to the press portion following the wire portion 10. When the amount of tap water is close to that of the headbox 11, the tap water must be collected. To this end, 15 loop water collection and control devices (not shown) are provided inside the loops formed by the web forming webs 12 and 12 '. With the collection and control devices, the tap water can be controlled in a controlled manner away from the wire section 10 to the operating side of the paper machine and further to the ledges 24 to the tap water tank 13, from which tap water is used for short circulation of the paper machine.

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Figure 2a is a side elevational view of a sectional view of the tap water tank 13 according to the invention. The tap water tank 13 is a substantially circular cylindrical cross-section forming a functional cyclone having a height substantially greater than 25 µm in diameter. In this case, the bubble escape distance is: as short as possible, but with sufficient volume, ···. minimum effort. The tap water is introduced into the tap water inlet 18 at the top of the cyclone tangentially along one or more inlets 24 at a high speed. From the overflow vessel, the tap water is further led to a circulating water tank 23. The tap water outlet 16 is located at the bottom 21 of the 35 vessel, whereby the tap water moves downwardly in the vessel. and is preferably connected to a paper machine air-conditioning system.

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According to the invention, a tray 14 is provided at the center of the tap water tank 13. The tray 14 is fixed at its upper end centrally to a deaeration port 17 on the ceiling of the tap water tank 13 and at its lower end a tray 14 hangs free. The length of the saloon 14 is substantially equal to the cylindrical vessel 22 of the tap water tank 13.

The mandrel 14 has a protruding mandrel design as shown in Figure 2b. A flat surface 15 covering two blocks 23, or at least a substantial part thereof 10, between two adjacent projections 14.1 and 14.2 is attached below the salon 14.

The operation of the tap water tank according to the invention is as follows. In addition to gravity, the tap water is moved by its own kinetic energy, for utilization of which the inlet conduit 18 is arranged substantially parallel to the tangent of 15 vessels. As the tap water flows rapidly in the tangential direction of the vessel, a vortex 26 is formed inside the vessel, where the tap water is mixed in a controlled manner. The air separated from the tap water collects in the center of the vortex 26, the passage of which to the tap mixing pump 20 is detrimental to the whole process.

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The protruding salon 14 disposed in the center of the tap water tank 13 slows down the center of the tap water vortex 26. This allows air bubbles in the tap water to rise upwards in the 25 channels formed between the two adjacent legs 14.1 and 14.2. Without rising to the ceiling of the tap water tank 13, it is mechanically sucked out through a deaeration port 17. Salon 14 projection-. ···. for example, star shaped (Fig. 2b), screw thread or moon crescent (not shown) are preferred. However, essentially, the shape of the block 14 is slowing down the vortex flow 26. Below the saloon 14, which is provided for the removal of air-30, there is attached a planar body 15 covering the blocks 23 ... formed by two adjacent projections 14.1 and 14.2, which prevents the saloon 14 from slowing down the tap water into the tap water tank 13: for the downwardly tapered outlet cone 21, and further 35 for the mixing pump 20. The planar body 15 may be a flat '· *' plate or it may also be shaped, for example, cone-shaped, to engage the tray 14 with either flat side (Fig. 2a) ) or tip.

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Figure 2b illustrates well the positioning of the inlet connection 18 in the container. The inlet conduit 18 is also strongly tapered, whereby tap water flows into the vessel as a steady jet from the inlet conduit 18 full. Contrary to the prior art, increasing the speed of the tap water 5 improves the operation and efficiency of the tap water tank 13. Adequate vortex in the 26 vessels is achieved with tap water having a velocity of at least 3 m / s when exiting the wire section. Generally, the tap water tank must be set at a height that ensures a sufficient flow rate in the cyclone to separate the air. In the ßο shaped vessel of the circular cylinder, the vortex 26 is naturally formed in the center of the vessel. As a result, the air-conditioning connection 17 and the venting section 14 are arranged substantially at an imaginary vertical central axis of the vessel so that the suction provided by the air-conditioning is at the salon 14 located at the suction point of the vortex 26.

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In addition, to prevent air re-mixing, the bottom of the vessel is fitted with a straight cone 21. At the bottom of the vessel there is sufficient tap water with only small air bubbles and low flow.

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Essential to the invention is a tangential inlet 18 for a cyclone wire water tank receiving rotary circulation and a special venting means therein, wherein the tap water; motion energy effectively removes air.

25 The structure of the arrangement is simple and reliable.

: Highly flowing tap water will also not precipitate, ···. so that the need for cleaning is minimal.

'* .1 ^ The space requirement of the arrangement is also smaller and structures can be placed more freely than before. In addition, the size of the wire 30 water container 13 can be substantially reduced, which is advantageous for the entire paper machine and production process.

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Claims (5)

110796 Patent Claims v A method for evacuating air from a paper machine tap water tank (13) comprising a cylindrical vessel (22), an inlet flange (24) and a vent (17) associated with the upper part of the cylindrical vessel (22) and a lower water outlet (16) is formed into a functional cyclone into which tap water is introduced tangentially through the inlet nozzles (24) to provide an air-separating vortex flow (26), characterized in that the rotational speed of the flow tank (13) at the central axis is slowed down A paper machine tap water tank formed by a cylindrical vessel (22), an inlet flange (24) and an air outlet connection (16) connected to the upper part of the cylindrical vessel (22) and a tap water reservoir (13) formed as a functional cyclone, (24) is tangentially connected to the cylindrical vessel (22) and a central deaeration connection 20 (17) is provided at the top of the tap water tank (13), characterized in that a slot (14) is arranged at the center axis of the tap water tank (13) projections (14.1, 14.2) that resist the vortex flow (26). * »* · · I *; 25 A tap water tank according to claim 2, characterized in that said flap (14) is arranged at a height substantially to the height of the cylinder (22) and extending substantially from the top to the vent (17). . 30 4. A tap water tank according to claim 2 or 3, characterized in that the tongue (14) and the projections (14.1, 14.2) are arranged * * *; * to form a star-shaped cross-section. A tap water tank according to any one of claims 2 to 4,. 35, characterized in that a planar surface (15) is arranged beneath the salon (14) to cover the blocks (23) between adjacent projections (14.1, 14.2) or at least a substantial part thereof. 110796