FI123014B - Structure of bottom diluent in a cyclone cleaner, and process in a structure of bottom diluent in a cyclone cleaner - Google Patents

Description

Swirl cleaner bottom diluent structure and method in the swirl cleaner bottom diluent structure

OBJECT OF THE INVENTION 5

The present invention relates to a bottom diluent structure of a vortex cleaner comprising at least a flow passage, a dilution water inlet for supplying the dilution water to a flow passage, and an outlet for directing the dilution water out of the bottom dilution to the vortex cleaner. The invention further relates to a vortex cleaner having a pulp feed connection for feeding pulp to a vortex cleaner, a separation cone for separating impurities from the pulp, a debris removal port, and a pulp discharge port. The invention further relates to a method in a bottom diluent of a vortex cleaner, wherein the dilution water is supplied to a bottom dilution combination, and the dilution water supplied to the bottom dilution outlet is led through a bottom dilution outlet outlet to a vortex cleaner.

BACKGROUND OF THE INVENTION Vortex cleaners are used, for example, in the process of treating recycled pulp used in papermaking, which aims to remove harmful impurities (reject) from the recycled pulp. Recycled pulp from which major impurities have been removed in an earlier process step such as coarse sorting is fed to a vortex cleaner. The vortex cleaner aims to provide a turbulent flow to the pulp 25, whereby the centrifugal force and the gravity cause the heavier parts of the pulp to sink into the lower portion of the vortex cleaner where they can be removed. The operating principle of the vortex cleaner is illustrated in Figure 1, in which the pulp to be treated is fed from the side of the vortex cleaner 1 through the pulp feed port 2 so that the mass fed at high flow rate is rotated within the walls 1a of the vortex cleaner. At least a portion of the wall of the vortex cleaner forms a separation cone 5, the diameter of which is reduced such that the diameter is smaller near the contaminant discharge connection 3 than at the half of the cone of the mass supply connection 2. The heavier parts of the pulp are then exposed to the outer circumference of the vortex 35 and pressed down until they can be removed through the debris removal connection 3 from the process. Instead, the lighter weight particles 2 migrate with the vortex to the upper portion of the vortex cleaner, which has a pulp outlet 4 to remove the purified pulp from the vortex cleaner 1 and lead it to the other steps of the process.

5 Dilution water is supplied to the vortex cleaner 1 via a bottom dilution port 6, which is intended to provide better separation of impurities in the vortex cleaner 1. Such vortex cleaners include e.g. such a problem that the bottom dilution line 6 may become clogged e.g. because the pulp to be cleaned gets inside.

10

Pulp pulverized pulp is often first treated with a high-consistency vortex cleaner to separate sand and / or other heavy particles from the pulp from the pulp to avoid such abrasive material being subjected to other processing steps. Thereafter, the pulp-15 pulp may be treated, for example, with a coarse screener whose accepted fraction, i.e., accept, may be subjected, for example, to low consistency vortex cleaning and reject to high consistency vortex cleaning. The vortex purification steps following the coarse sorter complement the separation of high density heavy particles in the circular fiber mass from the circular fiber mass. The wheel-20 purifiers can also be used in reverse, where they are used to separate a light material such as styrox, whereby the higher density and heavier fraction is the accepted fraction, i.e. the accepted mass, or the accept. The consistency of the pulp to be treated in high-consistency vortex cleaners is often in the order of 1-4%. On the other hand, the consistency of the mas-25 sludge, which is to be treated in dilute consistency vortex cleaners, is generally 0.5-1.5%.

C \ J

δ ™ Brief Summary of the Invention

C/O

It is an object of the present invention to provide an improved structure and method of bottom dilution of a g 30 vortex cleaner

CL

^ to implement. The invention is based on the idea that there is a valve structure open at the bottom of the waveguide inside the vortex cleaner

CD

° the pressure of the dilution water, which closes in a situation where the pulp to be purified would have a chance to pass into the dilution water connection.

More specifically, the bottom diluent structure of the vortex cleaner according to the present invention is essentially characterized in that the bottom dilution assembly further comprises a dilution water flow control member arranged to be movable between the first and second positions, the outlet outlet closed in the first position and open, wherein the opening of the outlet connection is arranged to be a function of the feed pressure of the dilution water and the pressure exerted on the dilution water flow control device in the vortex purifier. The vortex cleaner according to the present invention is essentially characterized in that the bottom dilution assembly further comprises a dilution water flow control means arranged to be movable between first and second positions, with the outlet in the first position closed and the outlet in the second position open. arranged as a function of the feed pressure of the dilution water and the pressure exerted on the dilution water flow control means in the vortex purifier. The method of the present invention is essentially characterized in that the flow of dilution water through the outlet is controlled by a control means having at least a first position and a second position in which the outlet is closed in the first position and the outlet is open in the second position. la-20 as a function of the feed water feed pressure and the pressure exerted on the dilution water flow control device in the vortex cleaner.

In a preferred embodiment of the invention, the bottom dilution joint has a spring for enhanced operation.

The inner structure of the bottom dilution head can be shaped to determine the optimal direction of the dilution water exiting the bottom dilution head.

ab cp o The bottom dilution unit closure member may include a construction that allows rotation of the g 30 closure portion as well as an outlet from the bottom dilution assembly.

CL

more even distribution of running water in the vortex cleaner.

00

S

° The self-closing dilution water supply technology prevents or at least reduces the ° probability of clogging of dilution water lines and lines. The construction of the invention enables relatively effective washing and dilution of impurities (reject) of the vortex cleaner locally in 4 desired areas. This allows for high feed consistency to the vortex cleaner and efficient separation efficiency.

The solution of the present invention is applicable not only to vortex purifiers used in connection with recycled fiber pulp processes (recycled pulp), but also to vortex purifiers used in mechanical pulp and chemical pulp processes. The vortex distin according to the invention can advantageously be placed in a process for the production or processing of pulp for the production of paper or board. Further, the location of the vortex cleaner 10 may be in the process of a short cycle of a paper or board machine. Some embodiments of the vortex cleaner of the invention are described herein without limiting the scope of the invention to them.

15 Description of the drawings

The present invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 shows a schematic view of the operation of a vortex cleaner, Figures 2a and 2b show a bottom dilution operating principle of a vortex cleaner according to a preferred embodiment; in a bottom dilution of an i 00 o vortex cleaner according to a preferred embodiment, og 30 4a-4c

CL

illustrate another preferred embodiment of the invention

CD

”In the bottom dilution of the vortex cleaner

CD

o operation of the spring-loaded valve used, δ

CVJ

Figures 5a-5c illustrate still further preferred embodiments of the invention, and Fig. 5d shows a detail of a bottom dilution relationship according to the embodiment of Fig. 5c, in simplified form.

Detailed Description of the Invention

Next, the operating principle of a bottom dilution of a vortex cleaner according to a first preferred embodiment of the invention will be described with reference to Figures 2a and 2b. Figures 2a and 2b show a bottom dilution connection 6, 10 comprising a flow passage 7 having a first end 7a having a dilution water supply connection 8 for supplying dilution water to a bottom dilution connection 6 and a bottom The cross-section 15 of the flow channel 7 is not necessarily constant, but may have a conical section according to Figures 2a and 2b, for example, such that the cross section of the flow channel 7 is larger at one end 7b of the flow channel than at the first end 7a. The outlet connection 9 may also be an opening.

The bottom dilution connection 6 further comprises e.g. a lid part 10 which acts as a regulator for the flow of dilution water, i.e. a kind of valve. The lid portion 10 is secured to the flow channel 7 of the bottom suction connection so that the lid portion 10 can move somewhat, preferably through the inlet 8, in the flow direction of the dilution water flowing into the flow channel 7. 25 In the example of Figure 2, this direction of motion is up and down. The movement of the cover portion 10 is limited in one direction by one end 7b of the flow passage 7, and in the other direction by the stop members 11 attached to the cover portion 10, thus the cover portion may move between the first position and the second position. These stop members 11 comprise, for example, one or more nuts that are threaded in connection with a threaded rod 12 or the like which may be present in the cover member 10.

CL

I do. Such a solution enables e.g. the movement of the cover part 10

C/O

“(Clearance G) in the flow direction of the dilution water (upwards in Figure 2) can be

C/O

o Adjust if necessary. This movement makes it possible to adjust the amount of flow through the bottom suction port 6 S as needed.

35 6

If necessary, a seal may be provided in connection with the lid portion 10, by means of which the sealing of the bottom dilution nozzle 6 can be further improved.

The cross-section of the cover member 10 in the direction of flow is, for example, circular 5, but may also have other shapes, such as oval or rectangular. In the accompanying drawings, the diameter of the point of the lid section 10 facing the other end 7b of the flow passage in the closed position is indicated by the letter D.

Next, the operation of the bottom dilution assembly 6 according to the first preferred embodiment 10 of the invention for controlling the supply of dilution water will be described. When the vortex cleaner 1 is in operation, the pulp to be cleaned is fed through a mass feed line 2 into a separation cone 5. The mass is then circulated within the separation cone and the centrifugal force and gravity cause the heavier particles to move toward the a pressure P1 is applied to the cover portion 10 of the inlet valve 6 in an effort to press against the other end 7b of the flow duct of the bottom dilution head. Thus, the pressure P1 causes a force effect F1 on the cover portion 10. Thus, if the dilution water 20 is not supplied to the bottom dilution line 6, the pressure P2 within the bottom dilution line flow channel 7 is less than the pressure P1 applied to the lid portion 10. This causes the lid portion 10 to press against the other end 7b of the bottom dilution passage flow passage 7, thereby closing the outlet port 9. This prevents or at least reduces the solids in separator 5 from entering the bottom dilution passage 6. This position of the lid portion 10 is referred to herein as the first position 2b.

Similarly, in the case where the dilution water is supplied through the dilution water g 30 feed line 8 to the bottom dilution line 6, the pressure in the feed valve

CL

inside the background channel 7 grows. At the point when the pressure P2 obtained by the dilution water at-co $ 2 inside the flow passage 7 is greater than that of the lid portion 10

CD

The pressure P1 or the force F2 exerted by the pressure P2 is greater than the force 35 F1 exerted by the pressure P1 on the lid portion 10, the lid portion 10 moves away from the flow passage 7, thereby opening the flow path through the bottom dilution port outlet 9 to the dilution chamber this position of the lid member 10 is referred to in this application as the second position, i.e. the lid member open position shown in Figure 2a. The flow of dilution water prevents, or at least reduces, the entry of any particles in the separation chamber 5 into the bottom dilution port 6. Thus, blockage of the bottom dilution port outlet 9 can be effectively prevented.

Also, gravity may have some effect on the lid portion 10, whereby the force F2 exerted by the pressure P2 is greater than the force F1 caused by the pressure P1 applied to the lid portion 10 and the force effect caused by the gravity. In practice, the effect of gravity is often relatively small compared to P1, in which case gravity does not necessarily need to be specifically considered.

In one embodiment, the condition for opening the outlet connection 9 may also be represented by the following formula: The outlet connection 9 opens when P2 * A2> P1 * A1, i.e. P2 / P1> A1 / A2, when the gravity acting on the cover portion 10 is negligible.

Figure 3 shows a bottom dilution assembly 6 according to another preferred embodiment of the invention. The difference with the embodiment of Figures 2a and 2b is mainly the design of the lid portion 10. In this embodiment, the lid part is also a spherical body with an inner surface 10a intended to cause the liquid flow 25 from the bottom dilution port 6 to be obliquely downwardly, i.e. towards the bottom of the separation cone 5 where the impurity outlet 3 is located. In the situation of Fig. 2a, the liquid flow from the bottom dilution compound 6 is directed substantially perpendicularly away

C/O

9 of the bottom dilution connection 6. The outlet direction of the liquid flow can be controlled o by appropriately selecting the radius r and angle α of the inner surface 10a of the lid portion 10, FIGS. 4a to 4c illustrate a bottom dilution of a vortex cleaner according to a third preferred

C/O

The structure and function of the base dilution assembly 6 used in

O

cv all right. The bottom dilution connection 6 comprises a spring 13 or the like which provides a force effect on the lid portion 10. The direction of this force effect is selected to move or press the lid portion 10 towards one end 7b of the flow passage 8 7 or against it. In this case, the pressure P2 generated by the filing liquid flow in the flow passage 7 must be greater than that of the bottom dilution nozzle 6 operating without air in order for the lid portion 10 to move and the outlet port 9 to open. However, the sealing of such a solution may be even better than that of the bottomless dilution nozzle 6 operating without the spring in the situation where the dilution liquid 6 does not flow through the bottom dilution nozzle 6 to the separation cone 5.

In the situations of Figures 4a and 4b, the outlet conduit is open and in the situation of Fig. 4c 10, the outlet conduit is closed.

Figures 5a-5c further illustrate the structure and function of the base dilution coupling 6 used in conjunction with the bottom dilution of the vortex cleaner according to a fourth preferred embodiment of the invention. Fig. 5a shows a bottom dilution connection 6 with a lid portion which is spherical but has a substantially flat surface, whereby the liquid flow from the bottom dilution connection 6 is directed substantially perpendicular to the bottom dilution connection 6.

Figure 5b shows a bottom dilution connection 6 with a lid portion which is spherical but has an oblique surface, with the liquid flow from the bottom dilution connection 6 directed obliquely downwards. The direction of this fluid flow can be influenced e.g. suitably selecting the angle of the bevelled portion of the underside, for example, by simulating or testing various angles.

Fig. 5c shows a bottom dilution line 6, partially similar to Fig. 5b ™, but with flaps 14 or the like added to the cover portion 10, which allows a more even distribution of the liquid flow from the bottom dilution line 6 and the bottom dilution line outlet 9 £. 30 staying clean still improves. The effect of these wings is that

CL

the flow causes the lid portion 10 to rotate about its axis, which "can further enhance the fluid flow from the bottom dilution port 6

CD

9 even distribution, o C \ 1 35 Under normal use, the bottom dilution connection 6 typically becomes a liquid, i.e. there is a gap between the lid portion 10 and the other end 7b of the flow channel.

9 In the event of a malfunction, the bottom dilution line 6 closes, i.e. the gap between the cover portion 10 and the other end of the flow passage 7b closes. This protects the base dilution compound 6 from clogging.

The amount of dilution water flowing through the bottom dilution nozzle 6 into the separation cone can be adjusted in various ways utilizing the solution of the invention. One way to control the dilution water flow rate is to change the pressure P2 of the flow dilution head 7 of the bottom dilution. Adjustment of the pressure P2 can be accomplished, for example, by varying the throttle of the valve 10 provided in the dilution water supply pipe. The volume flow through the outlet of the bottom dilution nozzle 9 or orifice increases as the pressure P2 is increased and correspondingly decreases as the pressure P2 is reduced. The volume flow rate of the bottom dilution outlet outlet 9 changes by changing the pressure P2 even though the cross-sectional area of the bottom diluting outlet outlet 9 remains constant. Correspondingly, the opening of the outlet connection 9 is also resisted by the pressure P1 applied to the separation cone 10, whereby the opening of the outlet connection 9 of the bottom dilution may depend on the pressure ratio P2 / P1 if the pressure P1 applied to the separation cone 10 changes during operation of the vortex cleaner.

On the other hand, the cross-sectional area of the bottom dilution outlet outlet 9 can be arranged to be continuously variable under the influence of pressure P2. This arrangement is possible, for example, when the bottom dilution connection includes a spring 13 shown in Figures 4a to 4c, wherein the spring 13 resists the movement of the cover portion 10 of the bottom dilution assembly, i.e. opening of the cross-sectional area 25 of the outlet 9. The higher the pressure P2 is arranged, the greater the cross-sectional area of the outlet. Of course, the opening of the ™ outlet connection 9 is also resisted by the action of the separation cone 10

C/O

o the pressure P1, whereby the opening of the outlet of the bottom dilution connection 9 may be o dependent on the other hand the pressure ratio P2 / P1, if the pressure P1 on the separator cone 10 may also change.

CL

CD

$ 2 One way to adjust the cross-sectional area of the bottom dilution outlet 9

C/O

For use during operation, it is provided to the bottom dilution joint 6 as a sealed export through the wall of the bottom dilution joint 6, which can change the position of the stop member 11. The position of the stop member 11 can be changed by means of the arm 10, for example by turning, when the stop member 11 comprises a threaded rod and a nut for adjusting the position of the outlet of the bottom dilution joint.

By increasing the flow of dilution water to the separation cone, the washing of the rejectable material can be enhanced so as to largely prevent reject of acceptable mass. The acceptable material is then washed from the reject material and, with the acceptance flow, exits the vortex cleaner 1 through the mass removal connection 4. Similarly, it may be necessary to increase the proportion of material to be reject from the feed pulp, for example, because of the presence of a flow of material to be re-10 through the reject unit or impurity outlet 3, whereby the reject material 15 is largely separated from the pulp to be treated.

Adjustment of the amount of dilution water can also be arranged to be variable based on the volume flow of the reject flow. As the volume flow rate of the reflux flow decreases, the volume flow rate of the dilution water can be arranged to increase, thereby increasing the volume flow rate from the 20 rejection ports 3. Correspondingly, as the volume flow rate of the rejection flow increases, the volume flow rate of the dilution water may be reduced, thereby reducing the volume flow rate from the rejection connection 3. The decrease in the flow rate of the reflux flow may be a sign of the onset of clogging of the vortex cleaner 1, which can be prevented by the added dilution water flow rate.

C \ J

It may be advantageous to arrange the δ ™ bottom dilution connection 6 so that the output outlet 9 included therein is closed during start-up of the vortex cleaner or when the use of the vortex cleaner 1 is stopped. This can prevent the mass g 30 from entering the outlet diluent outlet 9 of the vortex cleaner 1, which may

CL

^ clogs the outlet connection 9 and prevents it from functioning, whereby the bottom diluent 6 is "clean and functional when the vortex cleaner 1 is used again.

CD

O

Preferably, the bottom diluent outlet 9 is open during use of the vortex cleaner 1. However, the invention makes it possible, if necessary, to close or adjust the cross-sectional area of the bottom diluent outlet 9, which allows in many ways to control the dilution water flow through the outlet 9.

The flow through the outlet duct outlet 9 of the diluent can also be arranged to mouth 5 in the direction of the vortex cleaner mass supply line 2, i.e. the opposite direction as shown in the figures, i.e. upwardly, and even towards the mass removal line 2, i.e. directly upward. The direction of the dilution water flow through the bottom diluent outlet 9 can be arranged in the above manner upwardly or upwardly 10 by shaping the bottom diluent outlet 9 flow channel upwardly.

In the representations, the outlet diluent outlet 9 has a peripheral surface facing the bottom diluent 6. However, the bottom diluent outlet 9 may also be provided at a smaller diameter on the bottom diluent cover portion 10, whereby the dilution water flow from the bottom diluent through the outlet 9 can be easily directed more towards the vortex cleaner mass supply line 2 and the mass removal line 4. Still another embodiment of the present invention is that at least two outlet assemblies 9 as shown in the figures are provided in the bottom diluent cover portion 10, wherein the bottom diluent cover portion 10 opens at at least two different beams or at two different outlets 9. the support members 10 of the arrangement being overlapped by the sleeve members 25 supported on the same support shaft and the support arms supporting the cover members 10 therefrom.

CM

δ ™ The bottom diluent outlet 9 or fittings open and close when the pressure ratio P2 / P1 is changed appropriately or when the bottom diluent outlet 9 or fittings are arranged to open when the pressure ratio P2 / P1 changes.

CL

CD

In a preferred embodiment of the invention, the bottom dilution connection 6

C/O

comprises means for adjusting the volume flow of dilution water in the flow passage 7. These means may be arranged to control, for example, the supply pressure of the dilution water, the cross-sectional area of outlet 9, maximum opening of outlet 9 12 and / or spring force.

The present invention is not limited to the above embodiments, but may be modified within the scope of the appended claims.

C \ J

δ c \ j i oo o o

X

cc

CL

CD

00 δ o δ c \ j

Claims (20)

1. Bottom dilution piece (6) in a cyclone cleaner, comprising at least - a flow channel (7), 5. an inlet (8) for dilution water, for inputting dilution water into the flow channel (7), and - an outlet (9) for drainage of the dilution water from the bottom dilution piece (6) to the cyclone cleaner (1), characterized in that the bottom dilution piece (6) further comprises a control means (10) for the flow of dilution water, which is arranged movably between a first and a second position, in which the outlet position (9) is closed and in which second position the outlet (9) is open, the outlet (9) being arranged to open as a function of the relationship between the supply pressure (P2) of dilution water and the pressure (P1) affecting said control device ( 10) for the flow of dilution water in the cyclone purifier. Bottom dilution piece (6) according to claim 1, characterized in that the outlet (9) is arranged to open when the feed pressure (P2) of dilution water exceeds a predetermined first limit value. 20 Bottom dilution piece (6) according to claim 1 or 2, characterized in that the bottom dilution piece (6) comprises means for controlling the volume flow of dilution water in the flow channel (7). Bottom dilution piece (6) according to claim 3, characterized in that said means for controlling the volume flow of dilution water in the flow channel (7) is arranged to regulate the supply pressure of dilution water. oo o Bottom dilution piece (6) according to claim 3, characterized in that said means for controlling the volume flow of dilution water in flow; the duct (7) is arranged to regulate the transverse surface of the outlet (9). 00 CO Bottom dilution piece (6) according to claim 3, characterized in that said c3 means for regulating the volume flow of dilution water in the flow channel (7) is arranged to control the maximum opening of the outlet (9). Bottom dilution piece (6) according to any of claims 1-6, characterized in that the bottom dilution piece (6) further comprises a spring (13) arranged in conjunction with a lid part (10) to effect a force inversion on the lid part (10). ). 5 The bottom dilution piece (6) according to claim 7, characterized in that the bottom dilution piece (6) comprises means for regulating the spring force of the spring (13). Bottom dilution piece (6) according to any one of claims 1-8, characterized in that the lower surface of said lid part (10) is substantially uniform, the liquid flow from the outlet (9) being arranged to be directed substantially perpendicularly out of the bottom dilution piece ( 6). Bottom dilution piece (6) according to any one of claims 1-8, characterized in that the lower surface of said lid part (10) is inclined, whereby the liquid flow from the outlet (9) is arranged to be directed obliquely out of the bottom dilution piece (6). Bottom dilution piece (6) according to any of claims 1-10, characterized in that the lower surface of said cover part (10) is provided with wings, the liquid flow in the flow channel (7) being arranged to effect a rotational movement in the cover part (10). to intensify the even distribution of the liquid flow out of the bottom dilution piece (6). 25 12. A cyclone purifier comprising: - a pulp inlet (2) for feeding pulp into the cyclone purifier (1), o - a peel-off cone (5) for pulp pollution, o - a puddle (3) for pollution, £ 30 - a drain (4) for pulp, and CL 2 - a bottom dilution piece (6) comprising at least one - a flow channel (7), CD o - an inlet (8) for dilution water, for entering ° dilution water into the flow channel (7) and an outlet (9) for discharging dilution water out of the bottom diluent (6) into the cyclone cleaner (1), characterized in that the bottom diluent (6) further comprises a regulator (10) for flowing dilution water, which is movably arranged between a first and a second position, in which first position the outlet (9) is closed and in which second position the outlet (9) is open, the outlet (9) being arranged to open as a function of the relationship between the supply pressure (P2) of the outlet dilution water and the pressure (P1) affecting said control means (10) for the flow of dilution water in the cyclone purifier. A method for feeding dilution water into a cyclone purifier (1) through a bottom dilution piece (6), in which method - dilution water is measured into the bottom dilution piece (6), and - the dilution water fed into the bottom dilution piece (6) is discharged through the outlet (9). ) in the bottom diluent (6) of a cyclone cleaner (1), characterized in that the flow of dilution water passing through the outlet (9) is controlled by a control means (10) having at least a first and a second position, in which first position the outlet (9) ) is closed and in which second position the outlet (9) is open, the outlet (9) being opened as a function of the relationship between the dilution water supply pressure and the pressure exerting said regulator for the dilution water flow in the cyclone cleaner. Process according to Claim 13, characterized in that the volume flow of dilution water in the flow channel (7) is controlled by controlling the supply pressure of dilution water. C \ J o 15. A method according to claim 13, characterized in that the volume flow 00 o of dilution water in the flow channel (7) is controlled by regulating the transverse surface of the outlet (9). CL 30 CL Method according to claim 13, characterized in that the volume flow "of dilution water in the flow channel (7) is controlled by controlling the maximum opening of the outlet (9). o C \ J Method according to any of claims 13-16, characterized in that said pressure needed for opening of the outlet (9) is controlled by means of a spring (13) connected to a cover part (10). 5 Method according to any one of claims 13-17, characterized in that the liquid flow from the outlet (9) is directed substantially perpendicularly from the bottom diluent (6). Method according to any of claims 13-16, characterized in that the liquid flow from the outlet (9) is directed obliquely from the bottom dilution piece (6). 20. A method according to any one of claims 13-19, characterized in that dilution water fed into the bottom diluent (6) is used to effect a rotary movement in the lid portion (10) to intensify the even distribution of the liquid flow out of the bottom diluent (6). C \ J δ c \ j i oo o o X cc CL CD OO δ o δ c \ j