Screen Plate and Pulp Screening Machine

Abstract

A screen plate for a pulp screening machine. On the side towards the rotor of the pulp screening machine, the screen plate has concave grooves. Except in the region of the grooves, an even gap is formed between the vane of the rotor and the surface of the screen plate, wherein the rotor vane front edge of the pulp screening machine is arranged at an angle to the grooves. Also, a pulp screening machine with the screen plate.

Claims

1. A screen plate (100) for a pulp screening machine having a rotor (110) with a vane having a front edge, comprising: a main body; and concave grooves (120) on the main body on a surface of the screen plate (100) towards the rotor (110) of the pulp screening machine, each concave groove (120) extending across a length between a bottom end and a top end, wherein wherein the screen plate (100) is configured to be arranged to provide an even gap between the vane of the rotor (110) and the surface of the screen plate (100) toward the rotor except in a region with a groove (120), and with the front edge of the vane of the rotor (110) at an angle to the length of each of the grooves (120).

2. The screen plate (100) according to claim 1, wherein the concave grooves (120) of the screen plate (100) are configured and positioned to form angles of greater than 90° relative to the front edge of the rotor vane across the entire length of the respective grooves (120).

3. The screen plate (100) according to claim 2, wherein each of the grooves (120) has a width that increases from a center portion of the screen plate (100) toward an outer portion of the screen plate (100).

4. The screen plate (100) according to claim 1, wherein each of the grooves (120) has a width that increases from a center portion of the screen plate (100) toward an outer portion of the screen plate (100).

5. The screen plate (100) according to claim 1, wherein each of the grooves (120) has a depth that increases from a center portion of the screen plate (100) to an outer portion of the screen plate (100).

6. The screen plate (100) according to claim 2, wherein each of the groves (120) has a width and a depth that increases from a center of the screen plate (100) to an outer portion of the screen plate (100).

7. The screen plate (100) according to claim 1, wherein each of the groves (120) has a width and a depth that increases from a center of the screen plate (100) to an outer portion of the screen plate (100).

8. The screen plate (100) according to claim 1, wherein each of the grooves (120) has a width and an open top end at an outer portion of the screen plate (100), and for a given groove (120), the width at the open top end is greater than the width at the respective bottom.

9. The screen plate (100) according to claim 2, wherein each of the grooves (120) has a width and an open top end at an outer portion of the screen plate (100), and for a given groove (120), the width at the open top end is greater than the width at the respective bottom.

10. The screen plate (100) according to claim 3, wherein each of the grooves (120) has a width and an open top end at an outer portion of the screen plate (100), and for a given groove (120), the width at the open top end is greater than the width at the respective bottom.

11. The screen plate (100) according to claim 1, wherein the screen plate (100) is flat.

12. The screen plate (100) according to claim 11, wherein each of the bottom and top ends of the grooves (120) is open such that a center portion of the screen plate (100) is in communication with its peripheral region via the grooves (120).

13. The screen plate (100) according to claim 1, wherein the screen plate (100) is curved.

14. The screen plate (100) according to claim 13, wherein the screen plate (100) is a cylindrical surface of a cylindrical screen basket.

15. The screen plate (100) according to claim 13, wherein the screen plate (100) is a conical surface of a conical screen basket.

16. The screen plate (100) according to claim 1, further comprising perforations or slots.

17. A pulp screening machine, comprising: a rotor (110) having a vane with a front edge, and a screen plate (100) having a main body and concave grooves (120) on the main body on a surface of the screen plate (100) towards the rotor (110), each concave groove (120) extending across a length between a bottom end and a top end, wherein the screen plate (100) is arranged to provide an even gap between the vane of the rotor (110) and the surface of the screen plate (100) toward the rotor except in a region with a groove (120), and with the front edge of the vane of the rotor (110) at an angle to the length of each of the grooves (120).

18. The pulp screening machine of claim 17, wherein the concave grooves (120) of the screen plate (100) form angles of greater than 90° relative to the front edge of the rotor vane across the entire length of the respective grooves (120).

19. The pulp screening machine of claim 17, wherein each of the grooves (120) has a width and an open top end at an outer portion of the screen plate (100), and for a given groove (120), the width at the open top end is greater than the width at the respective bottom.

20. The pulp screening machine of claim 17, wherein each of the bottom and top ends of the grooves (120) is open such that a center portion of the screen plate (100) is in communication with its peripheral region via the grooves (120).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 schematically shows a partial section view of an embodiment of the screen plate positioned relative to a rotor.

DETAILED DESCRIPTION

[0020] FIG. 1 schematically shows a preferred embodiment of the disclosed screen plate 100 in relation to a rotor 110 of a pulp screening machine. The screen plate 100 has a main body with concave grooves 120 on the side towards the rotor 110 of the pulp screening machine. Except in the region of the grooves 120, an even gap is formed between the vane of the rotor 110 and the surface of the screen plate 100 that faces the rotor 110. As shown, the concave grooves 120 of the screen plate 100 are configured to form an angle α greater than 90° relative to the front edge of the rotor vane along the entire length of the grooves (120). For example, FIG. 1 shows that three grooves intersect with the front edge of the rotor vane, and the angles formed by grooves and the front edge of the rotor vane are all greater than 90° at every intersection point.

[0021] As shown, the width of each of the grooves 120 increases from the center of the screen plate toward the outside (the curved edge shown in FIG. 1). The screen plate 100 is flat and both longitudinal ends of the grooves 120 are open, so as to provide communication between the center of screen plate 100 and its peripheral region.

[0022] The advantages of the inventive embodiments disclosed herein are as follows: the grooves provided instead of projections as known in the art allows a minimization of the gap between the rotor and the screen plate, which increases de-flaking efficiency as well as capacity. This reduces buildup of impurities, especially larger impurities, because it is hard for the impurities to stay between the rotor and the screen plate, and the smaller gap restricts impurities from entering the gap. Accordingly, power consumption of the pulp screening machine decreases. Additionally, the lower amount of impurities entering into the gap between the rotor and the screen plate, wearing is reduced accordingly.

[0023] Alternatively, in an embodiment not shown, the surface of the screen plate can be configured to have a curved surface. For example, the screen plate may form a cylindrical surface of a cylindrical screen basket or a conical surface of a conical screen basket. Using grooves instead of projections on any shapes of screen plate yields the same advantages and improvements described above.

[0024] Moreover, although FIG. 1 depicts a screen plate 100 with holes on the surface, it could be understood that said screen plate may also be a slotted screen.

[0025] 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 of this invention do not further limit the spirit and scope of this invention, which is defined by the claims.

REFERENCE NUMBER LIST

[0026] 100 screen plate [0027] 110 rotor vane [0028] 120 groove [0029] α the angle between the groove and the rotor vane front edge