Pulp Screening Machine

Abstract

A pulp screening machine has screen extending upward from the bottom of the pulp screening machine and a rotor which rotates around the outside of the screen. An accept outlet is provided inside the screen and a pulp outlet and reject outlet are provided outside of the screen. The rotor vanes of the rotor are cantilevered from the rotor base on top of the screen into the region of the screen, with the rotor vanes not being connected to each other in the region of the screen. The rotor vanes have a rigidity adaptable for de-flaking cooperatively with the outside surface of the screen.

Claims

1. A pulp screening machine, comprising: a screen (200) extending upwards from a bottom and defining an inside and an outside, a rotor (100) rotatable about the outside of the screen (220) and including rotor vanes (101) cantilevered from a base (102) thereof from a top of and into the inside of the screen (200), an accept outlet provided on the inside of the screen (200), a pulp inlet and a reject outlet provided on the outside the screen (200), wherein the rotor vanes (101) are not connected to each other on the inside of the screen (200), and the rotor vanes have a rigidity adaptable for de-flaking the pulp cooperatively with the screen.

2. The pulp screening machine (100) according to claim 1, wherein the screen (200) of the pulp screening machine is cylindrical and extends vertically upwards.

3. The pulp screening machine (100) according to claim 1, wherein the screen (200) is conical and widens outward as extending upwards.

4. The pulp screening machine (100) according to claim 1, wherein the screen (200) of the pulp screening machine is conical and tapers inward as extending upwards.

5. The pulp screening machine (100) according to claim 1, further comprising projecting strips (210) provided on an outside surface of the screen (200).

6. The pulp screening machine according to claim 5, wherein at least one of the projecting strips (210) on the outside surface of the screen (200) is angled relative to a front edge (110) of the rotor vanes.

7. The pulp screening machine according to claim 5, wherein the projecting strips (210) extend across a distance in the height of the screen (200) that is equal to a distance that each front edge (110) of the rotor vanes extends on the outside surface of the screen (200), and the projecting strips (210) extend across a height of the screen (200) that is equal to the distance that each front edge (110) of the rotor vanes extends.

8. The pulp screening machine according to claim 5, wherein several groups of strips (210) are provided on the outside surface of the screen (200) and together extend across the height of the screen.

9. The pulp screening machine according to claim 1, comprising concave grooves (220) provided on an outside surface of the screen (200).

10. The pulp screening machine according to claim 9, wherein the concave grooves (220) are angled to a front edge (110) of the rotor vane.

11. The pulp screening machine according to claim 9, wherein the grooves (220) have widths that increase from a top of the screen (200) toward a bottom of the screen (200).

12. The pulp screening machine according to claim 9, wherein the grooves (220) have depths that increase from a top of the screen (200) toward a bottom of the screen (200).

13. The pulp screening machine according to claim 9, wherein concave grooves (220) on the outside surface of the screen (200) extend a distance in the height of screen (200) that is equal to a distance that each front edge (110) of the rotor vane extends.

14. The pulp screening machine according to claim 9, wherein several groups of the grooves (220) are provided on the outside surface of the screen (200) of the pulp screen machine and together extend across an entire height of the screen.

15. The pulp screening machine according to claim 1, wherein the screen (200) is perforated.

16. The pulp screening machine according to claim 1, wherein the screen (200) is slotted.

17. The pulp screening machine according to claim 16, wherein the slots of the screen (200) are angled relative to the front edge (110) of the rotor vane.

18. The pulp screening machine according to claim 16, wherein the slots of the screen (200) are angled relative to an axis of rotation of the rotor.

19. The pulp screening machine according to claim 1, comprising a junk trap provided tangentially on a housing of the pulp screening machine configured for removing coarse heavies from the pulp.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 schematically shows a section view of an embodiment of the pulp screening machine, wherein only the screen and the rotor are presented.

[0025] FIG. 2 schematically shows a section view of another embodiment of the pulp screening machine, wherein only the screen and the rotor are presented.

[0026] FIG. 3 schematically shows a section view of a further embodiment of the pulp screening machine, wherein only the screen and the rotor are presented.

[0027] FIG. 4 schematically shows an embodiment of the rotor and the screen of the disclosed pulp screening machine.

[0028] FIG. 5 schematically shows the projecting strips outside the screens of the pulp screening machine.

[0029] FIG. 6 schematically shows the screen and the rotor as disclosed herein.

[0030] FIGS. 7 and 8 illustrate the in-flow pulp screening machine according to the prior art.

DETAILED DESCRIPTION

[0031] FIG. 1 schematically shows a side section view in an embodiment of a pulp screening machine, wherein only the basket type screen and the rotor are presented. As FIG. 1 shows, the screen 200 of the pulp screening machine is conical which gradually tapers inward (narrows) as it extends upwards. The rotor 100 rotates about the axis A1 around the outside of the screen 200, wherein the accept outlet (not shown) is provided inside the screen 200, the pulp inlet (not shown) and the reject outlet (not shown) are provided outside the screen 200.

[0032] FIG. 2 schematically shows a side section view of another embodiment of the disclosed pulp screening machine, wherein only the screen and the rotor are presented. As FIG. 2 shows, the screen 200 of the pulp screening machine is cylindrical which extends vertically upwards. The Rotor 100 rotates around the outside of the screen 200 about the axis A2.

[0033] FIG. 3 schematically shows the section view in a further embodiment of pulp screening machine according to the present invention, wherein only the screen and the rotor are presented. As FIG. 3 shows, screen 200 of the pulp screening machine is conical which gradually tapers outward (widens) as extending upwards. The Rotor 100 rotates around the outside of the screen 200 about the axis A3.

[0034] The screen angle α, which refers to the angle between the screen and a horizontal plane shown in FIGS. 1 to 3, is preferably within the range of 45° to 135°, and more preferably 75° to 105°, which is subject to the applied furnishes and application conditions. It has been found that an angle <90° enhances the de-flaking, whereas the angle >90° improves the accept quality.

[0035] At comparable de-flaking efficiency, the tip speed of the pulp screening machine can be reduced by up to 30%, thereby reducing the power consumption remarkably and additionally prolonging the life of the basket and the rotor.

[0036] FIG. 4 schematically shows the rotor and the screen of the pulp screening machine in isometric view. As FIG. 4 shows, the rotor 100 is designed around the outside of the screen 200. Projecting strips 210 are provided on the outside surface of the screen 200. Strip 210 is applied to improve the de-flaking efficiency and to avoid the accumulation of the rejects (impurities) between the rotor 100 and screen 200. In different embodiments, strips can also be replaced with grooves to reach similar technical effects.

[0037] FIG. 5 schematically shows another embodiment of a rotor and the screen 200 of the pulp screening machine in isometric view. In this embodiment, the screen 200 includes concave grooves 220 on its outside surface.

[0038] Depending on the applied furnishes and application conditions, the embodiment with slotted baskets of FIG. 5 can be used instead of the embodiment with projecting strips of FIG. 4, resulting in better accept quality at still high de-flaking efficiency. The slots 230 are provided angled to the rotation axis, which enhances the transportation of the slurry and impurities from feed to reject side and keeps the screen basket clean.

[0039] FIG. 6 schematically shows an embodiment of the disclosed screen 200 and the rotor 100, wherein the screen 200 is slotted. One of the slots 230 on the outside surface of the screen 200 is shown in FIG. 6, which is provided angled to the front edge 110 of the rotor vane.

[0040] The above discloses the preferable embodiments of this invention, while the spirit and scope of this invention are not limited within the specific contents disclosed here. Those skilled in the art can develop more embodiments and applications according to teaching of this invention, and these embodiments and applications also belong to the spirit and scope of this invention. Therefore, it could be understood that the specific embodiments do not further limit the spirit and scope of this invention, which is defined by the claims.

REFERENCE NUMBER LIST

[0041] 100 rotor [0042] 101 rotor vane [0043] 102 rotor base [0044] 103 ring [0045] 110 front edge of the rotor vane [0046] 200 screen [0047] 210 projecting strip [0048] 220 concave grooves [0049] 230 slot