SEPARATION DEVICE

Abstract

A separation device having a housing (10) with a feed conduit (1) and a reject conduit (2), between which conduits (1, 2) and an accept conduit (3) of the housing (10) is a rotor unit (13) having a shaft (4) transverse to the through-flow direction of the separation device, which shaft rotates discs (5) attached to the shaft (4), the outer surface and/or side surfaces of which discs are jagged, i.e. they have protrusions (6) and/or notches and/or these surfaces are substantially rough and the teeth (9) of at least two sieves (7, 8) attached to the housing (10), extend between the discs (5), the first sieve (7) being between the reject conduit (2) and the accept conduit (3) and the second sieve (8) being between the feed conduit (1) and the accept conduit (3).

Claims

1. A separation device for separating oversized nieces from a liquid and solids containing suspension, the separation device comprising: a housing with a feed conduit and a reject conduit, and, between the feed conduit and the reject conduit is an accept conduit; a rotor unit in the housing, wherein the rotor unit includes a shaft transverse with respect to a through-flow direction of the liquid and solids containing suspension flowing through the separation unit, wherein the shaft rotates discs attached to the shaft, and an outer surface and/or side surface of the discs has protrusions, humps and/or notches, the teeth of at least two sieves attached to the housing extend between the discs, wherein the at least two sieves include a first sieve between the reject conduit and the accept conduit, and a second sieve between the feed conduit and the accept conduit.

2. The separation device according to claim 1, wherein a slope of a front surface of the protrusions on the discs is less than a slope of a trailing edge of the protrusions on the discs.

3. The separation device according to claim 1, wherein the discs are attached to the shaft and/or to each other by planar support members and/or rod-like support members parallel to the shaft.

4. The separation device according to claim 1, wherein separating slots between the rotor unit and the first and second sieves are equal.

5. The separation device according to claim 1, wherein a distance between the teeth of the first sieve differs from a distance between the teeth of the second sieve.

6. The separation device according to claim 1, wherein at least one of the first and second sieves is attached to the housing by a tinge or a slide.

7. The separation device according to claim 5, wherein the attachment to the housing of at least one of the first and second sieves is movable in response to an impact of a reject piece.

8. The separation device according to claim 1, wherein the second sieve is close to the accept conduit than to the feed conduit.

9. The separation device according to claim 1, wherein the second sieve is closer to feed conduit than to the rejects conduit.

10. The separation device according to claim 1, wherein a front surface of at least some of the protrusions of at least some of the discs has a convex shape and/or a taped, the trailing edge.

11. The separation device according to claim 1, wherein distances from a center of the shaft to a first of the humps of the discs differs from a distance from the center of the shaft to another of the humps.

12. The separation device according to claim 1, wherein at least some of the teeth of the sieves taper towards an apex and/or a front surface and/or a trailing edge of a respective one of the teeth.

13. The separation device according to claim 1, wherein at least some of the protrusions on the discs of the rotor unit are oriented in a rotational direction.

14. The separation device according to claim 1, wherein the first sieve and/or the second sieve is a double sieve comprising two distinct sieves.

15. The separation device according to claim 1, further comprising at least one sensor configured to sense magnetism, ultrasound, acceleration, acoustic emissions and/or pressure measurements and is attached to at least one of the reject conduit, to a rotary feeder attached to the separation device, to the sieves and/or to the housings.

16. A separation device comprising: a housing defining an inner chamber and a feed conduit, a reject conduit and an accept conduit each defining a passage to the inner chamber; discs in the inner chamber and mounted to a shaft, wherein the discs are configured to be rotated by the shaft about an axis transverse to a flow direction of a liquid and solids suspension which enters the feed conduit, flows through the inner chamber and exits the accept conduit; the discs each have protrusions extending radially outward; a first sieve attached to the housing and extending into the inner chamber, wherein teeth on the first sieve interlace with the protrusions of the discs, wherein the first sieve is positioned such that as the protrusions pass through the teeth of the first sieve as the discs rotate away from the accept conduit and towards the feed conduit; and a second sieve attached to the housing and extending into the inner chamber, wherein teeth on the second sieve interlace with the protrusions of the discs, wherein the second sieve is positioned such that as the protrusions pass through the teeth of the second sieve as the discs rotate away from the reject conduit and towards the accept conduit.

17. The separation device according to claim 16, wherein the protrusions have a trailing surface sloped at a greater angle than a slope of a front surface of the protrusions.

18. The separation device according to claim 16, a distance between the teeth of the first sieve differs from a distance between the teeth of the second sieve.

19. The separation device according to claim 16, at least one of the first and second sieves is attached to the housing by a hinge or a slide.

20. The separation device according to claim 16, wherein the first sieve and/or the second sieve is a double sieve comprising two distinct sieves.

21. The separation device according to claim 16, wherein the protrusions have outer surfaces that are jagged.

22. The separation device according to claim 16, wherein the protrusions on each disc are arranged in an annular array around the disc.

23. The separation device according to claim 16, wherein the protrusions on one of the discs is offset from the protrusions on another of the discs along a direction parallel to the axis.

24. The separation device according to claim 16, wherein the protrusions include at least one of humps and notches.

Description

LIST OF DRAWINGS

[0016] FIG. 1 illustrates a preferred embodiment, where the second sieve is close to the accept conduit,

[0017] FIG. 2 illustrates another preferred embodiment of the location of the second sieve,

[0018] FIG. 3 illustrates a preferred embodiment of a sieve,

[0019] FIG. 4 illustrates a preferred embodiment of the separation unit from the direction of the feed conduit,

[0020] FIG. 5 illustrates a preferred embodiment, where the discs are attached to each other with support members parallel to the shaft,

[0021] FIG. 6 illustrates a preferred embodiment of the rotor unit in cross section, where the discs are attached to each other with support members parallel to the shaft,

[0022] FIG. 7 illustrates a preferred embodiment, where the front surface of the protrusion of the disc is rounded and the back surface is tapered,

[0023] FIG. 8 illustrates a preferred embodiment, where the sieves are arranged movable, and

[0024] FIG. 9 illustrates preferred embodiments of the protrusions, humps and notches.

DETAILED DESCRIPTION OF THE INVENTION

[0025] FIG. 1 illustrates a preferred embodiment of the separation device having a housing 10 with a feed conduit 1 and a reject conduit 2, between which conduits 1 and 2 and an accept conduit 3 a rotor unit 13 is arranged. The rotor unit 13 has a shaft 4 transverse with respect to the through-flow direction, which shaft 4 rotates discs 5 attached to the shaft 4, and at least two sieves 7 and 8. The shaft 4 is advantageously in horizontal position. The outer surface of the discs 5 is provided with protrusions 6. Between the discs 5 there may be support sleeves 11, which keep their distances equal. More advantageous direction of rotation is marked in the Figure. The rotational speed of the discs 5 is advantageously between 200-1000 rpm. Advantageously at least some protrusions 6 of different discs 5 are at various locations in the rotational direction of the shaft 4. Advantageously the shaft is provided with a tube shaft 12, onto which the discs 5 and optional support sleeves 11 are arranged as a rotor unit 13. It is advantageous to make the discs 5 identical, but they can have a different number of various protrusions 6.

[0026] The teeth 9 of two sieves 7, 8 attached to the housing extend between the discs 5, of which sieves the first sieve 7 is between the reject conduit 2 and accept conduit 3. The second sieve 8 is between the feed conduit 1 and the accept conduit 3. The second sieve 8 is located adjacent to the accept conduit 3. Reject pieces cannot pass through the obstacles formed by the sieves 7, 8, the discs 5, the protrusions 6 and the shaft 4 or the support rings 11, but they are passed due to gravity and the impact the protrusions 6 into the reject conduit 3, via which the reject pieces are removed e.g. by means of a rotary feeder.

[0027] Advantageously one or more sensors 14 are attached to the reject conduit 3, the rotary feeder connected to the separation device or a corresponding device, to the sieves or in the vicinity of the sieves for indicating blockages and/or the filling of reject channels. The sensors 14 are connected to the control of the separation device or to process control. Sensors based on magnetism allow detecting a ferromagnetic metal piece. Ultrasound allows detecting solid pieces. Acoustic emission and/or acceleration sensors allow detecting deviations in sounds generated by the device, as well as collision of flowing pieces to structures of the device, and vibrations of the device. Pressure measurements allow detecting blockages in the separation device.

[0028] Pieces in the pulp flow that are at a density close to that of the pulp, and especially fibrous pieces, float better in the flow and they can advantageously remain to be torn, crushed and/or ground mostly at the slots between the protrusions 6 and the first sieve 7. The smaller the angle between the front surface of the sieve 7, 8 and the front surface of the protrusion 6 or the substantially round outer surface, the more likely the degrading takes place. The bigger the angle is, the better reject pieces are guided out of the separation unit. The angle can be of different size in different sieves 7, 8. Also the dimensions of the separating slots may be optimized in different sieves 7, 8 to be of different size. The sieves 7, 8 can be in different orientations and at different locations than in the presented drawings.

[0029] FIG. 2 illustrates a corresponding separation device as FIG. 1, but its second sieve 8 is located near the feed conduit 1, whereby it guides the separated pieces better into the reject conduit 2. This sieve 8 can also be placed at the same location as a doubled second sieve 8, together with the second sieve 8 of FIG. 1.

[0030] FIG. 3 illustrates a preferred embodiment of the sieve 7, 8. Tips of the teeth 9, which extend between the discs 5 of the sieve 7, 8 are advantageously made in the thickness direction thinner than the base of the sieve 7, 8.

[0031] FIG. 4 illustrates the solution according to FIG. 1 seen from the direction of the feed conduit 1. The shaft 4 is supported on bearings to the housing 8 at the end of the motor that rotates the shaft. The end of the shaft 4 is preferably provided with a filler piece 14 between the ends of the sieves 7, 8, which filler piece forms the separating slots between the end of the shaft 4 and the sieve 7, 8. The shaft 4 can also be bearing-mounted to the housing 8 at its one end. The filler piece 14 can also act as bearing housing for the shaft 4.

[0032] FIGS. 5 and 6 illustrate a preferred embodiment, where the discs 5 are attached to the shaft 4 and to each other with support members 51, 52 parallel to the shaft 4. Because an open space is formed in the center of the rotor unit 13, acceptable pulp can pass also through the center part of the rotor unit 13. Planar support members 51 transmit the rotational force of the shaft 4 and support the discs 5. Rod-like support members 52 mainly act as sieves, if the distances between the planar support members 51 are too big. The mutual distances of the support members 51, 52 are preferably substantially of equal size as the separating slots of the rest of the structure. The shaft 4 can have a length equal to that of the rotor unit 13 or it can be shorter, whereby the center of the separation section is completely or partially open. The shaft 4 can also be divided so that the drive shaft 4 extends only to the outermost disc 5 and the other end of the rotor unit 13 is supported by a bearing-mounted support shaft to the housing 10 or to the filler piece 14.

[0033] The rotor unit 13 allowing through-passing flow can be designed so that the discs 5 are either closed or open at their center. If the rod-like support members 52 extend through the perforations of the discs or are adequately supporting and fixed to the discs, planar support members 51 are not needed. At least the outermost discs 5 have to be attached at their center opening either to the shaft 4 or to the support shaft of the other end, in order to make the rotor unit 13 robust enough without planar support members 51. Support sleeves can be provided on the rod-like support members 52 between the discs 6, which support sleeves determine the distance between the disc, if the rod-like support members 52 are not otherwise fixed to the discs.

[0034] FIG. 7 illustrates a preferred cross section of the protrusion 6 of the disc 5. The front surface of the protrusion is convex and the trailing edge is tapered for decreasing the flow resistance. The tooth of the sieve 7, 8 can be shaped in a corresponding way. A tapered trailing edge does not intensively draw and collect behind itself fibers and pieces, which might accumulate a blockage.

[0035] FIG. 8 illustrates some solutions, where the sieves 7, 8 are arranged movable. The movement possibility allows e.g. removing blockages. The first sieve 7 is hinged, whereby it can be rotated by means of an actuator most preferably counter currently, whereby a reject piece is pushed into the reject conduit 2. If the shaft of the joint 81 is e.g. spring-loaded, the sieve 7 can occasionally yield co-currently, when it is subjected to an excess force. A sensor or a switch connected to the sieve 7 or its hinge can indicate data on a coincident or an excess force to the control of the separation device or to process control or an operator. The second sieve 8 can be moved by means of an actuator of the slide 82 closer to or further from the discs 5. One or more of the sieves 7, 8 can be differently movable and located at various points of the housing 10. If there are more than two sieves 7, 8, moving at least one of the doubled sieves 7, 8 aside when needed is an especially advantageous possibility.

[0036] FIG. 9 illustrates on the left-hand side protrusions 6 on the outer surface of the disc, the protrusions having a gentle sloping front surface and a sharper trailing edge. Most advantageously the protrusions 6 have in the radial direction a height of 10-50 mm. Smaller notches or humps 90 are shaped or attached to the disc 5 or its protrusions 6. Their function is to assist in tearing, crushing and/or grinding pieces against the sieves 7, 8. A hump 90 can extend to the side of the protrusion. It can be fixed upon the front surface of the protrusion 6. Advantageously, said humps 90 or notches are located at various distances from the center of the disc 5.

[0037] The right-hand side illustrates an embodiment where the protrusions on the outer surface and the sides of the disc are humps 91 and/or notches at corresponding locations. Then the disc 5 is substantially circular. When the notches or humps 91 are of adequate size, they can act almost as the presented bigger protrusions 6. Instead of or in addition to protrusions 6, humps or notches 6, 91, the outer and side surfaces of the disc 5 can have knurling, grooving or roughening. Embodiments presented in this patent application can be used in connection with each other, though they have not been separately mentioned.