US3804244A

US3804244A - Toroidal vortex cleaner

Info

Publication number: US3804244A
Application number: US00254468A
Authority: US
Inventors: K Skardal
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-05-21
Filing date: 1972-05-18
Publication date: 1974-04-16
Anticipated expiration: 1991-04-16
Also published as: DE2225005A1; IT957981B; SE352541B; DE2225005B2; JPS5138802B1; GB1360122A; FR2138916A1; SU450418A3; CA960611A; FR2138916B1

Abstract

A vortex cleaner for removing impurities from fibre suspensions, in particular high-consistency pulp and paper-stock suspensions, comprises a toroidal vortex chamber, which is provided with an annular, slot-shaped inlet opening for the fibre suspension to be treated extending coaxially relative the axis of symmetry of the toroidal vortex chamber, and means for injecting the fibre suspension to be treated into the vortex chamber through said annular inlet opening substantially over the entire length thereof in such a manner that the injected fibre suspension has a direction of flow in each point along the annular inlet opening, which includes a substantial flow component which is tangential relative the cross-section of the vortex chamber at said point, whereby the injected fibre suspension forms a helical vortex flow in the vortex chamber about the circular center line of the toroidal vortex chamber. An internal, generally radial partition wall is provided in the toroidal vortex chamber and has a substantially centrally disposed opening with a substantially smaller diameter than the cross-sectional diameter of the vortex chamber. A discharge conduit for the accept fraction of the fibre suspension being treated is connected to said opening in said partition wall on the one side of the partition wall and a discharge opening for the reject fraction of the fibre suspension being treated is disposed in the wall of the toroidal vortex chamber close to said partition wall on the opposite side thereof.

Description

O United States Patent 1 1 1111 3,804,244 Skardal Apr. 16, 1974 TOROIDAL VORTEX CLEANER [5 7] ABSTRACT [76] Inventor: Karl Arvid Skardal, Artillerigatan A t x cl a er for removing impurities from fibre 114 Stockholm, Sweden suspensions, in particular high-consistency pulp and z 197 paper-stock suspensions, comprises a toroidal vortex [22] Flled May 2 chamber, which is provided with an annular, slot- [21] Appl. No.: 254,468 shaped inlet opening for the fibre suspension to be treated extending coaxially relative the axis of symmetry of the toroidal vortex chamber, and means for in- [30] Foreign Apphcanon Pnomy D jecting the fibre suspension to be treated into the vor- May 21, 1971 Sweden 6600/71 tex chamber through said annular inlet p g stantially over the entire length thereof in such a man- [22] }J.S.(l. 209/21l02lc0/35(1N2) net that the injected fibre suspension has a direction 1 'f 210 5/12 of flow in each point along the annular inlet opening, 8] 0 care /2 5 which includes a substantial flow component which is tangential relative the cross-section of the vortex chamber at said point, whereby the injected fibre sus- [56] References cued pension forms a helical vortex flow in the vortex UNITED STATES PATENTS chamber about the circular center line of the toroidal 1,941,449 1/1934 Sylvan 55/407 vortex chamber. An internal, generally radial partition 2,255.807 9/ 1941 Dlumlee t 209/2ll wall is provided in the toroidal vortex chamber and 216511312 9/1953 Black 1 209/144 has a substantially centrally disposed opening with a substantially smaller diameter than the cross-sectional eu e erg diameter of the vortex chamber. A discharge conduit 2,986,277 5/1961 Ehlermann 209 144 x for the accept fraction of the fibre Suspension being FOREIGN PATENTS OR APPLICATIONS treated is connected to said opening in said partition 477,791 10/1951 Canadaw; 209/144 all n the on side f the partition wall and a dis- 894,l94 10/1953 Germany; 209/211 charge opening for the reject fraction of the fibre sus- Primary Examiner-Frank W. Lutter Assistant Examiner-Ralph J. Hill Attorney, Agent, or Firm-Eric H. Waters pension being treated is disposed in the wall of the toroidal vortex chamber close to said partition wall on the opposite side thereof.

18 Claims, 10 Drawing Figures PATENTEDAPR 16 m4 3,804,244

SHEET 1 OF 6 IWHIIIHI l l m PATENTEDAFR 1 61914 SHEET 2 BF 6 ITHIII '1 PATENTE APR 1 6 i974 SHEET 3 n? 6 PATENTED 1 6 74 SHEET 5 0F 6 TOROIDAL VORTEX CLEANER BACKGROUND OF THE INVENTION The present invention relates to a vortex type separator or cleaner for the removal of impurities from fibre suspensions, in particular pulp and paper-stock with a comparatively high consistency of about 3 percent or higher. Such so called high-consistency pulp or paperstock is obtained, for example, when disintegrating waste paper in water for re-use. Such high-consistency stock contains therefore a considerable amount of coarse impurities such as paper clips, paper staples, nails, bundling strip iron, string pieces,'stones, gravel and sand as well as clods of undefibered paper kept together by staples. These impurities must be removed from the stock or they will cause damage and wear on the downstream equipment for the treatment of the stock, such as refiners etc.

For removing impurities from high-consistency stock one has up to now used vortex cleaners of substantially the same type as for low-density pulp. These ,vortex cleaners consist in principle of a vertical, downwards conically tapering vortex chamber, to which the fibre suspension to be cleaned, the so called inject, is sup plied at the upper end of the chamber in such a way that the suspension forms a downwards moving helical vortex flow in the chamber, whereby the centrifugal force moves the heavier 'impuritiesin the suspension towards the wall of the vortex chamber. Under the influence of the gravity force andthe downwards moving helical vortex flow the impurities sink along the wall towards the lower end of the vortex chamber, where the fraction containing the impurities, the so called reject, is discharged from the vortex chamber. The cleaned portion of the fibre suspension, the so called accept, is concentrated, due to its lower specific gravity, to the axial central part of the vortex chamber, often as an inner upwards moving helical vortex flow, and is discharged through a pipe, a so called vortex finder, projecting coaxially into the vortex chamber at the upper or lower end thereof;

The result aimed at with the cleaning process is of course that the discharged reject shall contain only impurities and water but no useful fibres, whereas the accept shall be completely free from impurities and contain only useful fibres. When using vortex cleaners of the prior art type described above for the cleaning of high-consistency stock, that is pulp suspensions with a relatively high consistency of 3 percent and higher, it has been found difficult, however, to obtain this desired result. Often one will get an accept which still contains a considerable amount of impurities. This is particularly the case when one tries to obtain a reject not containing any considerable amount of useful fibres. The reasons for these difficulties when using prior art vortex cleaners seem primarily to be that the time of residence for the fibre suspension in the vortex chamber will be rather short and that the tangential or peripheral flow velocity in the vortex flow and thus the centrifugal force decreases considerably in the lower part of the vortex chamber. Therefore, in a high-consistency fibre suspension, the impurities will not be efficiently separated towards the wall of the vortex chamber, but a large amount of the impurities will instead be discharged together with the accept.

In this prior art type of vortex cleaners the necessary vortex flow is generally produced in that the inject is fed in a peripheral or tangential direction into the upper end of the vortex chamber. The necessary energy for the maintenance of the vortex flow in the vortex chamber is consequently supplied to the vortex flow exclusively at the upper end of the vortex chamber. For high-consistency fibre suspensions, however, this results in a rapid decrease of the tangential flow velocity in the vortex flow due to friction losses in the fibre suspension itself and between the fibre suspension and the wall of the vortex chamber. Therefore, for highconsistency fibre suspensions the high tangential flow velocity in the vortex flow at the upper end of the vortex chamber is not maintained further down in the vortex chamber. Particularly in the lower part'of the vortex chamber, where the impurities are discharged, the vortex flow may be completely interrupted, whereby no separation at all will exist any more. In order to increase the peripheral flow velocity and thus the centrifugal forces in the vortex flow in a vortex cleaner for high-consistency stock one has in some cases provided a motor-driven impeller at the upper inlet endof the vortex chamber, by means of which the necessary tangential flow velocity for the vortex flow is imparted to the inject being supplied to .the vortex chamber. lnspite of this, however, the vortex flow is still unsatisfactory,

- as also in this case the energy supply to the vortex flow SUMMARY OF THE lNVENTlON The object of the present invention is therfore to provide an, improved vortex cleaner, in particular for the cleaning of fibre suspensions with a high-consistency of about 3 percent and higher.

For this object the invention concerns a vortex cleaner for removing impurities from a fibre suspension, in particular a fibre suspension having a comparatively high consistency, which comprises a vortex chamber having substantially the shape of a toroid, the wall of said toroidal chamber being provided with an annular, slot-shaped inlet opening for the fibre suspension to be treated extending coaxially relative the axis of symmetry of the toroidal chamber, means for feeding the fibre suspension to be treated into the toroidal chamber through said annular inlet opening along substantially the entire length thereof with a direction of flow in each point along the inlet opening having a substantial flow component which is tangential relative the cross-section of the toroidal chamber at said point along the inlet opening, and a first transverse partition wall within said toroidal chamber, said partition wall being provided with a substantially centrally located opening having a smaller diameter than the crosssectional diameter of the toroidal chamber, said opening in the partition wall communicating on one side of the partition wall with a discharge conduit for the accept fraction of the fibre suspension being treated and the wall of the toroidal chamber being provided with a the invention;

discharge opening for the reject fraction of the fibre suspension being treated, said discharge opening being located close to the opposite side of said first partition wall.

As in the vortex cleaner according to the invention the vortex chamber has the shape of a toroid, a vortex chamber of a considerable length is obtained, in which consequently the average time of residence for the fibre suspension will be long, and over the entire length of which necessary energy can be supplied continuously for maintaining a forceful vortex flow of the fibre suspension in the vortex chamber even if the suspension has a high consistency. This results in a very efficient separation of any impurities, even if the fibre suspension has a high consistency, whereby the accept discharged from the vortex cleaner will be substantially completely free from impurities and contain only useful fibres.

BRIEF DESCRIPTION OF THE DRAWINGS in which FIG. I shows by way of example a side view of a first embodiment ofa vortex cleaner according to the inventron;

FIG. 2 is a side view of the vortex cleaner shown in FIG. 1 as seen from the line II-II in FIG. 1;

FIG. 3 shows a section through the vortex cleaner along the line IIIIII in FIG. I;

FIG. 4 shows an axial section through the vortex cleaner along the line IVIV in FIG. 3;

- FIG. 5 shows a partial section through the vortex cleaner along the line VV in FIG. 3;

FIG. 6 shows a section similar to the section shown in FIG. 5 through a vortex cleaner with a somewhat modified design as compared with the vortex cleaner illustrated in FIGS. 1 to 5.

FIG. 7 shows schematically and in section a preferred device for discharging the reject fraction, that is the separated impurities. from the vortex cleaner;

FIG. 8 shows schematically an axial section through a second embodiment of a vortex cleaner according to FIG. 9 shows schematically and in axial section another embodiment of a vortex cleaner according to the invention; and

FIG. 10 shows schematically and in axial section still another embodiment of a vortex cleaner according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The vortex cleaner according to the invention, which is shown by way of example in FIGS. 1 to 5, comprises a substantially toroidal vortex chamber 1, which in the illustrated example is formed by two joined chamber halves la and lb. As most readily seen from FIG. 4, the toroidal wall ofthis vortex chamber 1 is not completely closed but provided with an annular inlet slot or opening 2, which extends along the entire circumference of the toroidal vortex chamber and through which the fibre suspension to be cleaned. the so called inject, is fed into the vortex chamber 1. The inject'is supplied through an inlet pipe 3, which extends coaxially through the inner central opening of the toroidal chamber 1 so that the rim 3a of its open end forms the radially inner edge of the annular inlet slot 2 to the toroidal chamber 1. As illustrated in FIGS. 1 and 2, the vortex cleaner is mounted with the inlet pipe 3 on top of a tubular column 4, which forms a support structure for the vortex cleaner and the upper part of which forms a direct extension of the inlet pipe 3 and to which the inject is supplied through a pipe connection 5.

As can be seen in FIG. 4, the upper chamber half la is provided with a conical cover 1c, which is integral with the upper half 1a and which joins the upper chamber half la along the radially outer edge of the annular inlet slot 2. A shaft 6 is journalled in the conical cover 10 coaxially relative the toroidal chamber 1. The upper end of this shaft 6 is coupled to a drive motor, which is not illustrated in the drawing but which can be mounted on a flange 1d on the upper chamber half 10. The lower end of the shaft 6., which projects inside the cover 10, carries a centrifugal impeller 7 including a hub 70, a conical impeller disc 7!; disposed close to the cover 1c and radial impeller blades 70. In FIG. 3 the circumferential rim of the impeller 7 and some of its blades are indicated with dotted lines. It is assumed that the impeller rotates in the direction indicated by an arrow 8 in FIG. 3. Under the action of the rotating impeller 7 the inject supplied through the inlet pipe 3 will be fed into the toroidal vortex chamber 1 through its annular inlet slot 2 in such a manner that within the toroidal vortex chamber the inject forms a helical vortex flow about the circular center line 9 in the toroidal chamber 1. This is achieved in that the centrifugal impeller 7 injects the inject suspension close to the wall of the vortex chamber 1 with a velocity vector, which has a first vector component which is tangential relative the substantially circular cross-section of the toroidal chamber 1 at the point of injection as well as a second vector component which is parallel to the circular center line 9 in the toroidal chamber 1. It is appreciated that the inject from the inlet pipe 3 is fed into the toroidal chamber 1 along the entire length of the annular inlet slot 2. It is also appreciated that the rotating centrifugal impeller 7 will not only inject the inject suspension into the toroidal vortex chamber I as described above but also contribute towards maintaining the described vortex flow of the inject suspension. already present in the vortex chamber 1. The necessary energy for the maintenance of this vortex flow of the inject suspension is consequently supplied continuously along the entire circumferential length of the vortex chamber 'It is appreciated, that in a vortex cleaner according to the invention it is possible to obtain a vortex chamber with a substantial length, in which consequently the average time of residence for the inject suspension be-' comes comparatively long, and over the entire length of which a forceful helically extending vortex flow of the. inject suspension can be maintained. In this vortex flow all heavier impurities will, under the effect of the centrifugal force, be concentrated towards the outer portion of the vortex flow. that is close to the wall of the vortex chamber I, whereas a portion of the inject suspension containing substantially only useful fibres is obtained in the more central portion of the vortex flow.

As most readily seen in FIGS. 3 to 5, the toroidal vortex chamber 1 is shut-off by an internal transverse partition wall l0, which is provided with an opening ll having a substantially smaller diameter than the crosssectional diameter of the vortex chamber 1. It is appreciated that the central portion of the vortex flow of the inject suspension in the vortex chamber 1, which central portion contains substantially only useful fibres. will pass through the opening 11 in the partition wall 10, whereas on the contrary the impurities, that is the so called reject, which is concentrated close to the wall of the vortex chamber 1 will be stopped by the partition wall and not permitted through the opening 11 in the partition wall. The impurities, that is the reject, which are stopped by the partition wall 1 are discharged from the vortex chamber 1 through a discharge opening 12 in the wall of the lower half lb of the. vortex chamber immediately in front of the partition wall 10, as seen in the direction'of rotation 8 of the impeller 7. A pipe conduit 13, serving-as a reject outlet, is connected to the discharge opening 12.

The accept fraction passing through the opening 11 in the partition wall 10 enters a space 14 (FIGS. 3 and 5), which is separated from the remaining portion of the toroidal vortex chamber 1 and is located between the partition wall 10 and a second partition wall 15, which is inclined and joins the partition wall 10 at its upper edge close to the annular inlet slot 2 of the vortex chamber 1. From this space 14 the accept fraction is discharged through an opening 16 in the wall of the lower half lb of the vortex chamber. A pipe conduit 17, serving as an accept outlet, is connected to this discharge opening 16.

It should be noticed that alternatively the pipe conduit 17 could be extended into the vortex chamber 1 and be connected directly to the opening 11 in the partition wall 10. However, the inclined partition wall causes less disturbances in the flow and thereby a smaller total pressure drop in the vortex cleaner.

As shown in FIGS. 3 and 5, the opening 11 in the partition wall 10 is preferably provided with a short pipe 18, which projects from the partition wall 10 opposite to the direction of rotation 8 of the impeller 7 and which functions as a so called vortex finder. This vortex finder 18 makes it still more certain that no impurities can pass through the opening 11 in the partition wall 10 together with the accept fraction.

As can be seen in FIG. 3, the partition wall 10 with the opening I1 is preferably positioned at an angle relative to the radial direction from the axis of symmetry of the toroidal chamber 1 and thus relative the radial blades 7c of the impeller 7 so that the blades 7c form an angle with the partition wall 10 when the blades pass the partition wall and so that the blade tips are the last portions of the blades passing the partition wall. This arrangement of the partition wall 10 gives the advantage that rejected impurities, which are for any reason not immediately discharged through the reject outlet 12, will be kept in rotation about the vortex finder 18 in front of the partition wall 10 by the blades 70 of the rotating impeller 7 so that they are given several opportunities to be discharged through the reject outlet 12. Otherwise, a substantial portion of such rejected impurities would be thrown by the impeller 7 past the partition wall 10 over its upper edge close to the impeller7, whereby these rejected impurities would be forced to make a second run through the toroidal vortex chamber.

As can be seen in FIG. 5, the blades 70 of the impeller 7 are preferably somewhat inclined relative to the disc 71) of the impeller. This gives the advantage that the inject suspension supplied from the inlet pipe 3 and in particular heavier impurities in the inject are forced by the blades 7c towards the conical impeller disc 7b, whereby the injection of the inject suspension into the toroidal vortex chamber 1 will take place as close as possible to the wall of the vortex chamber.

As explained in the foregoing, it is desired that the reject fraction being discharged from the vortex cleaner should contain substantially only impurities but no useful fibres. It is also desired that only small amounts of water should be discharged through the reject outlet. Both these objects are satisfied in a very efficient manner by a reject discharge device designed as schematically illustrated in FIG. 7.

FIG. 7 shows the lower portion of the discharge conduit 13, which is connected to the outlet opening 12 for the reject. This discharge conduit is connected through a transparent pipe section 19, a so called sight-glass, and a T-joint 20 to a substantially horizontal pipe 2]. This horizontal pipe 21 contains a piston 22, which can be moved by means of a pneumatic cylinder 23 or any other suitable device back and forth past the T-joint 20 has a stroke 24 with a length only slightly exceeding the diameter of the vertical branch of the T-joint 20. The opposite end of the pipe 21 is shut by a weighted flap 25, which primarily seals against the water pressure in the reject discharge conduit 13 so that only negligible amounts of water will leak through the pipe 21. Instead of a weighted flap it is of course possible also to use a spring-biased flap or some other suitable shutting device. When starting the operation of the vortex cleaner the outer end of the pipe 21 at the flap 25 could, when necessary and desired, be filled with loosely stuffed waste-paper, cotton waste or some similar material, which assists in preventing water leaking from the pipe 21 at the flap 25, until the pipe 21 becomes filled with reject. It is appreciated that rejected impurities discharged from the vortex chamber 1 through the reject outlet 12 will under the influence of their own weight fall through the reject discharge pipe 13 down into the pipe 21 immediately below the T-joint 20. At repeated intervals the piston 22 is moved by means of the cylinder 23 from its unoperative position illustrated in FIG. 7 to the left in the drawing past the T-joint 20, whereby the rejected impurities collected underneath the T- joint 20 are pushed to the left in the tube 21 towards the flap 25. The movement of the piston 22 is comparatively slow so as not to produce any pressure shock, which could result in a water leakage at the flap 25 or produce disturbancies in the flow at the reject outlet 12 from the vortex chamber. When the entire pipe 21 between the T-joint 20 and the flap 25 has become completely filled with rejected impurities, each additional stroke of the piston 22 will open the flap 25 and discharge some rejected impurities from the pipe 21. In order to prevent that useful fibres are discharged together with the rejected impurities through the reject discharge pipe 13, it is preferable, as known per se in water flow keeps the edge of the T-joint 20 furthest away from the piston 22 clean from impurities so that the piston 22 can be safely moved past the T-joint 20. In some cases it may be desired to clean a paper stock suspension in two stages. In such cases one discharges from a first vortex cleaner designed according to the present inventiona reject fraction which contains not only impurities but also a certain amount of useful fibres and which is fed, possibly after being diluted with additional water, to a second vortex cleaner, which may be of the conventional prior art type. From this second vortex cleaner an accept fraction is discharged, which contains some impurities and which is therefore returned or re-circulated to the first vortex cleaner. Consequently, the accept fraction from the second cleaning stage shall be supplied as an inject suspension to the first vortex cleaner, which is designed in accordance with the present invention. Naturally, this can be done by mixing the accept fraction from the second cleaning stage with the initial fibre suspension, before this is supplied to the vortex cleaner according to the present invention, that is to the first cleaning stage. However, the vortex cleaner according to the present invention can also be provided with a separate inlet for the accept fraction derivedfrom the second cleaning stage. FIG. 6 in the accompanying drawing shows such a modification of the vortex cleaner according to the invention which has been described in the foregoing and which is illustrated in FIGS. 1 to 5. FIG. 6 shows a partial section through the modified vortex cleaner corresponding to the section illustrated in FIG. 5. Identical parts in'thc modified vortex cleaner illustrated in FIG. 6 and the vortex cleaner illustrated in FIGS. 1 to 5 are provided with the. same reference numerals.

The modified vortex cleaner illustrated in FIG. 6 differs from the vortex cleaner illustrated in FIGS. 1 to 5 in that the toroidal vortex chamber 1 is provided with an additional partition wall 27, which is located on the opposite side of the inclined partition wall 15 relative to the partition wall 10 provided with the accept opening 11 and which joins the partition walls 15 and I0. at its upper edge so that a space 28 is formed between the

partition walls

27 and 15. In this space 28 the lower half lb of the vortex chamber is provided with anopening 29, which is connected to an inlet conduit 30 for the accept fraction derived from the second cleaning stage. The partition wall 27 is provided with an opening 31, which is located centrally in the vortex chamber 1 and has a substantially smaller diameter than the crosssectional diameter of the vortex chamber 1 and which is provided with a pipe 32 projecting axially into the vortex chamber 1. The accept fraction derived from the second cleaning stage is consequently fed through the pipe conduit 30, the opening 29, the space 28, the opening 31 in the partition wall 27 and the pipe 32 into the toroidal vortex chamber 1 into the center of the vortex flow which is formed in the vortex chamber 1 by the inject suspension which is injected by the impeller 7 from the inlet pipe 3 through the inlet slot 2 (FIG. 4). It is appreciated that various other embodiments of a vortex cleaner according to the invention are possible in addition to the embodiments described in the foregoing. Some alternative embodiments are illustrated schematically in FIGS. 8 to 10, which show axial sectionsthrough the vortex cleaners but in which all inlet and outlet pipes for the inject, the accept fraction and the reject fraction respectively have been omitted for the sake of simplicity.

Corresponding parts are provided with the same reference numerals as in FIGS. 1 to 5.

The vortex cleaner according to the invention and illustrated in FIG. 8 is mounted directly in the bottom of a pulper 33, from which the suspension is fed into the toroidal vortex chamber 1 by means of the rotating impeller 34. This impeller is provided with radial blades 34a on its upper side, which serve on one hand as agitators in the pulper 33 and also feed the suspension into the vortex chamber 1. However, the impeller 34 is also provided with blades 34b on its lower side. These blades are consequently located within the vortex chamber 1 and have as an object to maintain the helical vortex flow within the vortex chamber 1.

The embodiment of the invention schematically illustrated in FIG. 9 is similar in essential parts to the embodiment of the invention which is illustrated in FIGS. 1 to 5 and which has been described in detail in the foregoing and differs from thisvortex cleaner substantially only therein that the cover 10 of the toroidal vortex chamber 1 is flat instead of conical and that consequently the impeller 7has a plane impeller disc for the blades 70.

In the embodiment of the invention schematically illustrated in FIG. 10 the inject suspension is supplied through a descending pipe conduit 34 and is fed into the toroidal chamber 1 through its annular inlet slot 2 by means of a rotating propeller 36, which has its shaft 37 journalled-in the center of the toroidal chamber. The blades 36a of the propeller 36 project somewhat into the vortex chamber 1 so that they can assist in maintaining the helical vortex flow in the vortex chamber. As compared with the embodiments of the invention described in the foregoing the embodiment illustrated in FIG. 10 has the disadvantage that string pieces, bundling wires and similar impurities present in the inject suspension may get entangled in the propeller 36 and give cause to shut-downs.

What I claim is: I

l. A vortex cleaner for removing impurities from a fibre suspension, in particular a fibre suspension having a relatively high consistency, comprising a vortex chamber having substantially the shape ofa toroid, the wall of said vortex chamber being provided with an annular, slot-shaped inlet opening for the fibre suspension to be treated extending coaxially relative to the axis of symmetry of the vortex chamber, means for feeding the fibre suspension to be treated into the vortex chamber through said annular inlet opening substantially along the entire length thereof and with a direction of flow at each point along the inlet opening, which includes a substantial flow component which is tangential with re-' spect to the cross-section of the vortex chamber at said point along the inlet opening, a first internal partition wall in said vortex chamber, said first partition wall having an opening substantially centrally disposed therein and with a smaller diameter than the crosssectional diameter of the vortex chamber. a discharge conduit for the accept fraction of the fibre suspension being treated being connected to said opening on one side of said first partition wall. and the wall of the vortex chamber being provided with an opening serving as a discharge opening for the reject fractionof the fibre suspension being treated disposed close to said first partition wall on the opposite side thereof.

2. A vortex cleaner as claimed in claim 1, wherein a second internal partition wall is provided in said vortex chamber on said one side of said first partition wall and spaced therefrom so that a first space is restricted between said first and second partition walls, said first space being sealed relative to said annular inlet opening and communicating with the remaining portion of the vortex chamber only through said opening in said first partition wall, the wall of the vortex chamber being provided with a discharge opening for the accept fraction from said first space.

3. A vortex cleaner as claimed in claim 2, wherein said second partition wall is inclined relative to said first partition wall.

4. A vortex cleaner as claimed in claim 2, wherein a third internal partition wall is provided in said vortex chamber on the opposite side of said second partition wall relative to said first partition wall and spaced from said second partition wall so that a second space is restricted between said second and third partition walls, said second space being sealed relative to said annular inletopening, the wall of the vortex chamber being provided with an inlet opening to said second space for a secondary supply of fibre suspension to be treated, and said third partition wall is provided with an opening substantially centrally disposed therein and having a smaller diameter than the cross-sectional diameter of the vortex chamber.

5. A vortex cleaner as claimed in claim 4, wherein said third partition wall is provided with a short pipe surrounding said opening in the wall and projecting from the wall on the side thereof opposite to said second partition wall.

6. A vortex cleaner as claimed in claim 1, wherein said first partition wall is provided with a short pipe surrounding said opening in the wall and projecting from the wall on said opposite side of the wall.

7. A vortex cleaner as claimed in claim 1, wherein said means for feeding the fibre suspension to be treated into the vortex chamber through said annular inlet opening includes an impeller mounted coaxially relative to the axis of symmetry of the vortex chamber for rotation in a direction towards said opposite side of said first partition wall as seen in the circumferential direction of the vortex chamber.

8. A vortex cleaner as claimed in claim 7, wherein said impeller is a centrifugal impeller having its circumferential rim disposed at said annular inlet opening to the vortex chamber.

9. A vortex cleaner as claimed in claim 8, wherein said means for supplying the fibre suspension to be treated to said vortex chamber includes an inlet pipe extending coaxially relative the axis of symmetry of the vortex chamber through the center of the vortex chamber and having an open end with a rim forming the radially inner edge of said annular inlet opening to the vortex chamber. the centrifugal impeller being disposed opposite the open end of said inlet pipe with its circumferential rim close to the radially outer edge of said annular inlet opening to the vortex chamber.

10. A vortex cleaner as claimed in claim 9, wherein said centrifugal impeller comprises a conical impeller disc and radial impeller blades attached substantially over their entire radial length to said conical impeller disc on the side thereof facing the open end of said inlet pipe, the conicity of said impeller disc being such that the impeller disc is substantially tangential relative the wall of the vortex chamber.

11. A vortex cleaner as claimed in claim 10, wherein the radial outer edge of said annular inlet opening to said vortex chamber is joined circumferentially with a conical cover, said impeller being journalled in said cover with its conical impeller disc close underneath the cover.

12. A vortex cleaner as claimed in claim 9, wherein said centrifugal impeller comprises an impeller disc and radial impeller blades attached substantially over their entire radial length to said impeller disc on the side thereof facing the open end of said inlet pipe, said impeller blades being inclined relative to said impeller disc so that the longitudinal edges of the blades attached to the disc lag the opposite longitudinal edges of the blades, as seen in the direction of rotation of the impeller.

13. A vortex cleaner as claimed in claim 9, wherein said first partition wall in said vortex chamber is disposed at an angle relative to the radial direction to the axis of symmetry of the vortex chamber so that the blades of said impeller,'when passing said first partition wall upon rotation of the impeller, form an angle to said first partition wall and the radially outer tips of the blades are the last portions of the blades passing said first partition wall.

14. A vortex cleaner as claimed in claim 1, wherein said vortex chamber is mounted with its axis of symmetry vertical and said reject discharge opening is disposed in the lower portion of the wall of the vortex chamber.

15. A vortex cleaner as claimed in claim 1, comprising a substantially vertical pipe having one end connected to said reject discharge opening and its opposite end connected through a T-joint to a second, substantially horizontal pipe, a piston being disposed in said horizontal pipe on one side of said T-joint and being reciprocatingly movable past said T-joint.

16. A vortex cleaner as claimed in claim 15, wherein the end of said horizontal pipe on the opposite side of said T-joint is provided with closure means which can be opened against a biasing force.

17. A vortex cleaner as claimed in claim 15, comprising means for feeding water into said vertical pipe, preferably adjacent said T-joint.

18. A vortex cleaner as claimed in claim 15, wherein said vertical pipe is provided with a transparent section. =l

Claims

1. A vortex cleaner for removing impurities from a fibre suspension, in particular a fibre suspension having a relatively high consistency, comprising a vortex chamber having substantially the shape of a toroid, the wall of said vortex chamber being provided with an annular, slot-shaped inlet opening for the fibre suspension to be treated extending coaxially relative to the axis of symmetry of the vortex chamber, means for feeding the fibre suspension to be treated into the vortex chamber through said annular inlet opening substantially along the entire length thereof and with a direction of flow at each point along the inlet opening, which includes a substantial flow component which is tangential with respect to the cross-section of the vortex chamber at said point along the inlet opening, a first internal partition wall in said vortex chamber, said first partition wall having an opening substantially centrally disposed therein and with a smaller diameter than the cross-sectional diameter of the vortex chamber, a discharge conduit for the accept fraction of the fibre suspension being treated being connected to said opening on one side of said first partition wall, and the wall of the vortex chamber being provided with an opening serving as a discharge opening for the reject fraction of the fibre suspension being treated disposed close to said first partition wall on the opposite side thereof.

4. A vortex cleaner as claimed in claim 2, wherein a third internal partition wall is provided in said vortex chamber on the opposite side of said second partition wall relative to said first partition wall and spaced from said second partition wall so that a second space is restricted between said second and third partition walls, said second space being sealed relative to said annular inlet opening, the wall of the vortex chamber being provided with an inlet opening to said second space for a secondary supply of fibre suspension to be treated, and said third partition wall is provided with an opening substantially centrally disposed therein and having a smaller diameter than the cross-sectional diameter of the vortex chamber.

9. A vortex cleaner as claimed in claim 8, wherein said means for supplying the fibre suspension to be treated to said vortex chamber includes an inlet pipe extending coaxially relative the axis of symmetry of the vortex chamber through the center of the vortex chamber and having an open end with a rim forming the radially inner edge of said annular inlet opening to the vortex chamber, the centrifugal impeller being disposed opposite the open end of said inlet pipe with its circumferential rim close to the radially outer edge of said annular inlet opening to the vortex chamber.

13. A vortex cleaner as claimed in claim 9, wherein said first partition wall in said vortex chamber is disposed at an angle relative to the radial direction to the axis of symmetry of the vortex chamber so that the blades of said impeller, when passing said first partition wall upon rotation of the impeller, form an angle to said first partition wall and the radially outer tips of the blades are the last portions of the blades passing said first partition wall.

14. A vortex cleaner as claimed in claim 1, wherein said vortex chamber is mounted with its axis of symmetry vertical and said reject discharge opening is disposed in the lower portion of the wall of the vortex chamber. 15. A vortex cleaner as claimed in claim 1, comprising a substantially vertical pipe having one end connected to said reject discharge opening and its opposite end connected through a T-joint to a second, substantially horizontal pipe, a piston being disposed in said horizontal pipe on one side of said T-joint and being reciprocatingly movable past said T-joint.

18. A vortex cleaner as claimed in claim 15, wherein said vertical pipe is provided with a transparent section.