FI94442B - Method and arrangement for filling of a pulp tower or similar space - Google Patents

Description

94442

Method And apparatus for filling a mass tower or similar space

The present invention relates to a method and apparatus for filling a mass tower or the like. The method and apparatus according to the invention are particularly applicable to the filling of reaction tanks or pulp storage towers containing a thick fiber suspension in the wood processing industry.

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Many different ways to fill a mass tower are known in advance. First, the habits are divided into filling from either the top or the bottom. Filling from above is performed either by dropping the mass directly from either the central or tower connection portion 15 into the tower (US 4,521,380) or by allowing the mass to fall onto a special distribution plate or device (FI patent 50550) to distribute the mass evenly across the tower. From below, the filling is naturally characterized in that the mass has to be pumped into the 20-earth tower inside, so that the mass already in the tower is pushed upwards or at least to the side, so that there is enough space for the mass entering the tower.

! The filling from the bottom of the tower can be described as e.g.

25 SE in patent 172 981. This patent discloses a solution in which the mass is passed centrally through the bottom of the tower to a tower with a rapidly rotating impeller-like device intended to direct the mass to flow radially along the bottom of the tower. The aim is to make the mass 30 evenly distributed over the entire width of the tower. A similar solution is also described in the SE publication '. 452 345.

·· * Furthermore, a solution is also known which is very similar to the floor scraper more commonly used for emptying 35 towers, · ': by which the mass is transferred to the outlet at the bottom of the tower. P1132 / 9201 2 94442. The aim is to distribute the mass pumped into the tower evenly over the entire width of the tower.

Thus, in almost all known solutions 5, the aim is for the mass fed to the tower to be evenly distributed over the entire width of the tower or reactor. This is, of course, due to the fact that, especially in reactor tanks, the channeling of the pulp has a significant disadvantage in the form of an uneven end product. The ideal filling of the tower tapah-10 would be supported so that when the mass is fed from the bottom, it would be spread over the entire bottom surface of the tower, from where it would evenly raise the mass already in the tower.

Each of the solutions described above has its own drawbacks. A device that feeds mass radially from the center of the tower bottom distributes the mass evenly to the bottom of the tower, but the strong radial flow direction causes the mass column in the center of the tower to move remarkably slowly and the mass at the edges of the tower to rise rapidly. Thus, the reaction time of the pulp in the tower depends exactly on where in the tower the pulp particle happens to be.

The scraper is likely to achieve a somewhat better result when the pulp is applied with a precise finish of the scraper, but the scraper is very uneconomical due to its high power consumption, requiring the drive motor to still require a large space under the mass tower, increasing the overall tower height significantly. A further problem with both of these feeder solutions is that the shaft of the feeder must be provided with bearings and seals at the bottom of the tower, which, if damaged, lead to the entire tower being emptied in the worst case.

With the method and apparatus according to the present invention, it is possible to eliminate all the disadvantages of the prior art apparatus 1132/9201 3 94442 without having to provide bearings or seals on the tower bottom, the tower bottom can be quite flat, the overall height of the tower at least the power consumption does not increase compared to the lower solutions, and most importantly, the channeling of the mass in the tower can be virtually completely prevented.

The method according to the invention is characterized in that the mass is fed from several openings arranged in connection with the space to be filled into the space in question.

The apparatus according to the invention is characterized in that 15 more discharge openings connected to the flow channels are arranged in connection with said space to be filled.

In the following, the method and apparatus according to the invention will be described in more detail with reference to the accompanying figures, of which Figure 1 shows a schematic side view of an apparatus for filling a mass tower according to a preferred embodiment of the invention, and. Fig. 2 shows a section along the line A-A in Fig. 1.

According to Figures 1 and 2, the apparatus for emptying a pulp tower or reaction tank according to the invention consists of flow channels 16, 18, 20 and 22 connected to the bottom 14 of said pulp tower 12 supported on a support structure 10, connected at one end by valves 24 to the flow distributor 26. In Fig. 2, the fiber suspension is shown to come with a single '! *. along flow path 28. However, it is possible that pulp is directed to the distributor from several different sources, in which case said distributor can at the same time act both as a connecting and homogenizing state for future flows and as a · · *; as said combined flow sharing device. Said 4 94442 dispensing device 26 is described e.g. U.S. Patent 4,964,950. Said distribution device is characterized in that it is a relatively small volume device and that, according to a preferred embodiment, said space is provided with a rotating, preferably fluidizing rotor, which can efficiently combine and homogenize incoming mass flows and distribute the mass evenly from the distribution channels. The drive device 30 of the distributor 26 is either a motor connected directly to the end of the shaft 10 of the distributor or a pulley drive, whereby the drive motor can be driven on the side of the distributor. In the latter way, the overall height of the tower is somewhat lowered. The distributor described here is characterized in that it generates virtually no pressure difference at all, but all the energy supplied to it is used to distribute the flow. Thus, the mass entering the distributor must either be pumped there or the process pressure must be high enough to transfer the mass through the distributor to the tower.

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An alternative to the distributor in a situation where the process pressure is not sufficient is to use, for example, a centrifugal pump with several pressure orifices as described in U.S. Pat. In this case, the functions of the distributor 25 and the pump are performed by the same device 9 '1a. Both the distribution device and said distribution pump are characterized in that, when dividing the flow into smaller partial flows, they homogenize the pulp to a uniform quality, whereby, for example, a bleaching reaction can be expected to lead to a slightly smoother end product than in the prior art.

In addition, the dispensers described can very well also be used to mix either a liquid or gaseous bleaching chemical into the pulp or, possibly in some cases, also to uniformly mix the water used to dilute the pulp into the pulp. Furthermore, by slightly modifying the distributor, i.e. by adding gas separation devices known per se to the distributor, it is possible in some cases also to use the distributor to separate the gas 5 from the pulp.

The operation of the apparatus described above is characterized in that there are at least two, preferably more, flow channels leaving the distributor. Since, according to a preferred embodiment of the invention, an equal volume flow is supplied to the tower from each discharge opening of the flow channel by means of valves, the aim is to raise the pulp column evenly over the entire area of the tower. This can be ensured both by placing the discharge openings in the right places at regular intervals on the bottom of the tower and by arranging a sufficient number of discharge openings. The number of discharge openings depends on the diameter of the tower and the location of the openings in the radial direction on the shape of the cross-section of the tower and the flow resistance caused by any equipment in the tower.

20 Actually, the only accurate sizing instruction is to place the discharge openings at regular intervals on the bottom of the tower equidistant from the center of the bottom of the tower. For example, four openings every 90 ° ", five openings every 72 *", etc.

m • · 25 Of course, in some cases it is possible to think that “the openings are placed at different large radial distances, • in which case one option is also to adjust the flow with valves to different sizes in different channels. Of course, it is of course possible to use a distributor to supply the mass 30 to spaces other than cylinders. Thus J for example angular tanks or some annular ·. facilities may well be appropriate. However, at least for the present solutions, it is characteristic that the mass · 'is fed in a substantially vertical direction either from the bottom 35 upwards or from the top downwards to a substantially vertical ·. mode.

Pl132 / 9201 6 94442

As can be seen from the above, it has been possible to develop a completely new type of method and apparatus for filling mass towers, reaction vessels and the like. With the method and apparatus according to the invention, it is possible to keep the flow in the tower as constant as possible, whereby the fiber-pension reaction time in a bleaching tower, for example, remains constant for each fiber particle, unlike in prior art channeling and even leading solutions. It should be noted that only a few preferred embodiments of our invention have been described above, which are not intended to limit our invention in any way from what is described in the appended claims.

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Rl132 / 9201

Claims (13)

94442 -7 / A method for filling a substantially vertical space of a pulp tower or the like, in which method the mass 5 is fed into said space, characterized in that the pulp is fed from a plurality of openings arranged in connection with the bottom of said space into said space. A method according to claim 1, characterized in that before the pulp is fed into said space, the pulp from one or more sources is divided into partial flows. A method according to claim 2, characterized in that said partial flows are equal. Method according to Claim 2, characterized in that the pulp is divided into partial flows by a distributor with a rotating rotor. 20 A method according to claim 2, characterized in that said plurality of mass flows are combined into a single flow and divided into said sub-flows in a playing device. '25 A method according to claim 4, characterized in that a chemical, such as peroxide or alkali, is added to the pulp in said distributor, or that gas is removed from the pulp in said distributor. 30 Apparatus for filling a mass tower or a similar space, characterized in that a plurality of discharge openings connected to the flow channels (16, 18, 20, 22) are arranged in connection with the bottom of said space (12). 35 Apparatus according to claim 7, characterized in that there are at least two discharge openings. 94442 Apparatus according to claim 7, characterized in that said discharge openings are arranged at regular intervals in connection with said space (12). Apparatus according to claim 7, characterized in that said discharge openings are arranged at regular intervals on the bottom of the pulp storage tower (12) or reaction tank. Apparatus according to claim 7, characterized in that said flow channels (16, 18, 20, 22) have valves (24) for controlling the partial flows. Apparatus according to claim 7, characterized in that said flow channels (16, 18, 20, 22) are connected at one end to a so-called flow divider. to the distributor (26). Apparatus according to claim 12, characterized in that said distributor (26) is a centrifugal pump with a plurality of pressure orifices. «* • 9 9 • 9 9 9, 94442