FI118130B - Method and apparatus for filling a mass tower - Google Patents

Description

118130

Method and apparatus for filling the mass atom

The present invention relates to a method and apparatus for filling a mass atom. The invention is particularly well suited for the filling of thick pulp atoms, bleaching atoms, storage tanks and similar towers containing fiber suspensions in the wood processing industry.

Mass atoms are most commonly used in the wood processing industry to contain 10 tanks of a thick pulp, 10 to 20 percent consistency, though sometimes also of lower consistency, used, for example, to store pulp or as a storage container for a device, such as periodic pulp from batch diggers. flow in the following processing equipment. In other words, the towers which are the subject of the invention are characterized by a great variation in their height, although in most cases they have some optimum height at which the mass surface is usually maintained.

Many different solutions for filling mass atoms of the above type are known in the art. The oldest known method is to pump the mass to the top of the tower, from where it is allowed to fall more or less directly. If the mass is allowed to fall directly onto the mass below, it is clear that the falling from the high * * * : V mass penetrates the surface of the mass layer in the tower and penetrates deep inside the old mass. There are many drawbacks to this. First, if a dilution of the mass »· • · •" is performed at the bottom of the tower, it is always possible to penetrate the dilution zone. until. As a result, the mass is discharged uncontrollably into the dilution zone, and the smoothness of dilution is no longer what is required by the device following the tower. Another problem is that the mass, as it screams inside the old mass, drifts closer to the outlet of the tower than the mass already existing in the Toms, so that the contents of the tower do not change evenly, but part * · · • · '· · · * mass exits the tower in minutes, with some standing in the tower for up to "" 30 more weeks. This in turn causes further problems. First of all, it is not * * * conceivable that the mass standing on the tower for days or even weeks could remain of the same quality as the fresh mass Ρ! 401; 7σ * ά · »ι · α1 i 2 118130. Second, complete conversion in such towers can take days, at most several hours, whereby the mass to be unloaded from the tower is a blend of new and old pulp. Depending on.

from the next application of pulp, this so-called. intermediate mass to be completely unusable at worst. Further, as the old pulp stays longer in the tower and as the new pulp discharges deeper into the tower, liquid is gradually drained from the surface of the pulp layer, thereby hardening the surface layer and starting to deteriorate more easily.

10 Of course, the mass can also be disassembled on a distributor, for example a rotating plate (e.g. SE-B-463 030), which is distributed at the top of the tower and distributes the mass more evenly across the section of the tower. As the dispenser disintegrates into a drop of a mass stream, or at least a relatively small particle size, a significant amount of air is bound to the mass during the drop, which must be removed at later stages of the process by high energy-consuming vacuum pumps or similar waste systems.

In some towers, the pulp is brought from below to below the rotating and winged plate (SE-C-502,971) so that the pulp spreads the pulp to the cross-section of the tower.

It is stated that the speed of rotation of the electric motor used to rotate the rotating plate can be varied to achieve different mass widths, which is what it means: *: 20. This procedure has the same problems as the * * * • V rotating plate, that is, the mass drops and a lot of air is bound to the mass. Another problem is that the prior art rotating plates, or similar, do not, in our opinion, take into account the height of the tower * · · · · * »* * ..

* · '* Variations, but are only suitable for some standard height, which is still - 25 mostly a practically full tower, with the plate or the like positioned * *: only slightly above the surface of the mass in the tower. When Tom is empty - * * # *. The pi rotating plate throws the mass against the wall of the tower, whereby it at last drips and absorbs a large amount of air.

*: **: 30 US Patent 4,278,496 discloses a bleaching core filling arrangement in which * * t pulp is introduced into the tower through a rotating tubular joint so that the pulp is applied to M 401; To * nickname t, & '3 118130 sit towers. However, this is a continuous process where the height of the tower is - practically constant, and in our opinion it is not very important for the mass to be spread evenly on the tower, since the consistency of the mass entering the tower is 35-50%. With such high consistency, there is no intrinsic risk of the mass penetrating deep into the mass layer already in the tower, as long as the direction of mass supply is not quite vertical.

Another problem associated with the filling of mass atoms comes with batch cooking processes, and particularly with the filling of their buttoms. It is generally known 10 that when emptying a batch digester, the consistency of the pulp discharged from the digester varies greatly, resulting in zones of varying consistency which, in most cases, result in varying consistency of pulp to be transferred to the next process step. problems, for example, in washing the brown mass 15. After all, for example, scrubbers are rated for some optimum consistency, deviation from which will inevitably lead to reduced performance.

Another problem not addressed above relates to the storage of bleached pulp. In some cases, it is of paramount importance that the mass is unloaded from both the tumbling tower and the storage or buttress tank that may follow, so that the residence time of the mass in the tower or tank remains constant. In other words, no part of the mass must remain standing on the tower because its quality is diminished in one way or another.

a *: * ·· An example of this is shown in Fig. 1, which shows the lightness of the pulp to be removed from the tower as a function of the height of the surface of the tower, based on measurements made at a cellulose mill * · * v: First of all, we can see that the lightness of the mass decreases ·· * ·; In practice, this means that the longer the mass * I »* ·, '* stays in the tower, the lower the luminosity will be, i.e. in the optimum situation one should try to disassemble the mass in exactly the same order as it is fed into it • · ·! .. It can also be seen from the figure: *: ** 30 that when starting the tower filling according to the prior art method (straight 'h butt over the tower), the brightness of the mass to be removed from the tower increases again.', P1401; Totikanmi 4 118130 can only be explained by the fact that the butt entering the tower goes practically directly into the outlet of the tower, leaving the mass still in the edges of the tower without timely access to the exit.

The various problems of the prior art solutions described above can be solved by the method and apparatus of the present invention, the features of which are apparent from the appended claims.

In the following, the invention will be described in more detail with reference to the accompanying figures, of which Figure 1 illustrates graphically the problem encountered in the prior art mass atom, i.e., the lightness of the mass as a function of tower height;

According to Figure 2, the apparatus according to the invention comprises a rotatable feeder 12, an apparatus 14 for rotating it, a means 16 for applying pulp to said feeder 12 and a means 18 for feeding the pulp atom 10, preferably at the top or top of the tower 10, preferably · To guide the operation of a person. The devices 16 may consist not only of a tube routed through the tower lid in accordance with Figure 2, but also substantially of a tube extending through the side wall of the tower to the central axis of the tower or the like. According to a preferred 'embodiment of the invention, the feed member 12 is disposed at the lower end of a vertical pulp tube or the like with a tube having an outlet opening substantially directed * * * * towards the wall of the container or pulp atom 10. An essential feature of the feed member 25 is that it is not bulk-dripping, i.e. dripping, but tends to keep the mass-flow uniform, possibly preventing air from binding to the mass. It is irrelevant to the invention whether the pipe arch outlet ** «· ;;; horizontally, somewhat upwards or downwards, but that the direction of discharge of the mass from the outlet, together with the speed of rotation of said feed member 30, ensures that in all operating conditions of the tower the mass is also discharged into the wall of tower 10; beside. Preferably, the feed member rotation device 14 is adjustable-

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5 118130 low speed electric motor equipped with a reduction gear as needed.

Said operation controls 18 of the feeder 12 consist of a level sensor included in the standard equipment of each tower and a control unit 22.

The operation of the above described apparatus can be thought of in two examples.

The first is, for example, a situation in which the amount of mass entering the tower and the amount of mass leaving the tower are substantially equal, i.e., the height of the tower remains substantially constant. According to an advantageous embodiment 10 of the invention, the control unit 22 is initially provided with at least tower diameter information, information about the height of the feeder and information about the pressure and / or velocity of the incoming mass in the feeder 12. After receiving the tower height information, the control unit 22 the rotational speed of the feeder 12 by which the pulp jet discharged from the feeder 12 hits the junction of the wall and pulp surface of the tower 10. In practice, this is taken as the maximum rotation speed of the feed member 12. When the tower 10 is now filled in this situation, the control unit 22 maintains a constant rotational speed of its predetermined feeder 12 for a certain amount of time, for example, by supplying mass to the periphery of the tower by a change in height of about 50 em. Thereafter, the speed of rotation of the feeder 12 is reduced, evenly or incrementally, so that an equal amount of mass is obtained at each position ♦ ♦ ·: · '' (diameter of the tower). When calculating the rotational speed of the ···· ♦ '' * incrementally, it is taken into account that closer to the center of the tower the mass • · '' discharges to a smaller cross-section (at least due to radius shortening, * * · ** in some cases In other words, the maintenance time for each of the 25 individual rotations decreases as you approach the center of the tower.

· • a * * ··· • · · · · ·

As can be seen from the example above, it is possible to develop experience based • «· · ;; The control unit 22 calculates an algorithm based on which the control unit determines the required speed of rotation of the supply means 12 and its maintenance time. Another possibility, in accordance with another preferred embodiment of the invention, is to "teach" the control unit to operate in a predetermined manner in connection with the commissioning of each apparatus P1401 ^ ni * kcwui 6 118130. Such "teaching" is done by first determining, for each tower height (for example, at 1 m intervals) the maximum feeder rotation speed and the required lower rotational speeds and their maintenance times, which allow the tower to be filled in a substantially uniform manner. In such a case, based on the information provided by the level sensor, the control unit 5 selects from the information known to it which is used to control the operation of the feeder.

Another example is a situation where the tower is being filled or emptied, i.e. a situation where the height of the tower changes, i.e. the mass flow into and out of the tower 10 is unbalanced. In this case, the control unit 22 must be able to continuously monitor the height of the tower and draw from it the necessary changes in the control data of the feeder 12. In other words, the control unit 22 must take into account that when the height of the tower is low, the feed jet behaves differently than when the height of the tower is mid-15 or at the top of the tower. These aspects can best be "taught" to the control unit 22, as described above, i.e. when the equipment is commissioned, optimum values are determined for each surface height, both for the rotational speeds of the feeder 12 and for their maintenance times.

In another preferred embodiment of the invention, a feed member may be constructed such that the direction of the mass jet discharged therefrom is changed. , so also the distance • * • * 'from the axis of the tower to which the mass jet extends changes. This can be done e.g.

By arranging the direction of the outlet of the feed member to be changed, for example, by a special guide plate or chute which, when rotated in a substantially vertical plane, changes the direction and extent of the jet jet in the tower. Another option is to follow II * *. a stationary, rotatable, or rotatable baffle located substantially at a distance from the mouth of the tube to a substantially vertical feed tube, which can be displaced vertically • · · # · ··· *. When the plate is larger in diameter than the »30 tube orifice, the plate directs the mass jet farther from the center of the tower, the smaller the distance between the • orifice and the plate. The trackpad may be either horizontal

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P1401; larvae 118130 7 plate, although it is preferably conical in shape so as to direct the pulp to the side. In all of the embodiments described herein, it is possible to keep the rotational speed of the feed member constant and to change another parameter affecting the flight path of the mass fed to the tower. These parameters can be "taught" to the control unit already following the 5 principles described above, or it is also possible to develop a computation algorithm by which the control unit can determine the required trajectory changes to fill the tower smoothly. Of course, it should be noted that when using a straight or conical plate at the end of the feed tube, the feeder does not even need to rotate, but by changing the position of the baffle, the flight path of the Tor-10 mass discharged can be sufficiently affected.

As will be seen from the foregoing, a novel and numerous method and device for filling in atoms has been developed to overcome the disadvantages of the prior art devices and methods. However, only a few preferred embodiments of the invention are set forth above, which, however, are not intended to limit the scope of the invention as defined in the appended claims. It should also be noted that the shape of the tower does not necessarily have to be similar to that shown in the figure, i.e. the tower having a cylindrical base tapered with a convex intermediate portion, but may be cylindrical in height throughout with a flat or tilted base, or ··· · I '. ** 20 with conical or hemispherical base. In other words, the · · · tower filling solution according to the invention is suitable for filling any form of tower.

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Claims (14)

A method of loading a pulp container, in which method pulp is supplied to the pulp container (10) either by means of a feeder member (12) arranged in conjunction with its lid or at least its upper part, characterized in that the pulp is discharged from the feeder means (12) to the tower. as a uniform mass beam without decomposing the mass to minimize mixing of gas in the mass, and changing the flight path of the mass jet in the tower (10) to provide even loading of the tower (10). 10 Method according to Claim 1, characterized in that the range of the pulp beam discharged from the feeder means (12) is changed to provide even loading of the tower (10). 15 Method according to claim 1, characterized in that the pulp is uniformly discharged to the tower (10) on top of the pulp layer which is currently highest with regard to the different loading levels of the tower. Method according to claim 1, characterized in that the pulp is discharged to the ***. By distributing it evenly over the surface of the pulp layer which is already v. is in the tower. • · • «· • 1 · • · • · t Method according to claim 2, characterized in that the range of the mass beam j2 .. is changed by controlling the rotational speed of the feeder (12). Q: 25 Method according to claim 1, characterized in that the range of the pulp beam is changed by adjusting the direction of the pulp beam emitted from the feeder means (12). * ··· »• · ·« ··· '• · •: • 1 • · ♦ ·· · · • · • 1 2 • · # - 118130 Method according to claim 5 or 6, characterized in that the operation of the feeder (12) takes place as a function of the diameter of the tower (10) and the level height of the pulp. 5 Method according to claim 5, characterized in that the rotational speed of the feeder (12) is changed periodically so that the mass is fed as an annular layer to the thread, the tower being substantially uniformly filled. » Method according to claim 5, characterized in that the rotational speed of the feeder (12) is continuously changed such that the mass is supplied to the void helically, the tower being substantially uniformly filled. Method according to claim 1, characterized in that the flight path of the pulp jet is changed by adjusting the discharge opening for the pulp in the feeder devices. Apparatus for loading a pulp container, comprising: a pulp container (10) with walls, a bottom and bottom discharge pulping devices and devices (12, 14, 16) for feeding, ···. 20 of pulp to the tower (10), characterized by feeder means (12) for altering the flight path of the pulp jet in the tower (10) in order to achieve even loading of the tower (10) and of the tower (10) a level position indicator and a ♦ control unit (22), which also belongs to the feeder devices. • · • · 12. Apparatus according to claim 11, characterized in that the feeding devices comprise the driving means (14) of the feeding means (12), whose speed of rotation is controlled by the operating unit (22). ♦ · · • 1 • m • · · Apparatus according to claim 11, characterized in that the ·: ··: feed devices comprise a feeder (12) having an adjustable: · 1 rotation speed. • · «'. £ * 1 * 1 1 13 118130 5 Apparatus according to claim 11, characterized in that the feeder means comprise a feeder means which is adjustable to the direction of feeding of pulp. · 1 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 1 · · • · · * 1 1 1 * · • · • · 1 * * · • · ·· • · • ♦ ·. .ψ- 9 · * »• · • · ·