DEVICE FOR CLEANING FIBROUS SUSPENSIONS FOR PAPER PRODUCTION

Abstract

A device for cleaning a suspension, preferably a fibrous suspension for paper production. The device includes a screen basket, on the exterior surface of which the suspension to be cleaned is supplied and from the interior surface of which the screened accepted stock is released. A housing surrounds the screen basket. The housing includes an inflow for the suspension to be cleaned, an accepted-stock outlet for the cleaned suspension and a reject outlet for impurities. A scraping device rotates on the outside of the screen basket about the screen basket axis and has scraper blades (foils) which scrape along the exterior surface of the screen basket. The scraping device comprises a drum with a cylinder surrounding the screen basket. The cylinder carries a plurality of foils on its inside facing the screen basket.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:

FIG. 1 shows a cleaning device in diagrammatic representation in an axial section;

FIG. 2 shows a cleaning device according to FIG. 1, in an axially perpendicular section;

FIG. 3 shows an enlarged representation of a portion of a screen, in an axially perpendicular section;

FIG. 4 shows an enlarged representation of a drum with foils, in an axially perpendicular section;

FIG. 5 shows a drum with foils, in an axial section; and

FIG. 6 shows a view to an inside of the drum.

Claims

1. A device for cleaning a suspension, comprising: a screen basket, on an exterior surface of which the suspension to be cleaned is supplied and from an interior surface of which the screened accepted stock is released;a housing surrounding the screen basket, the housing comprising: an inflow for the suspension to be cleaned,an accepted-stock outlet for the cleaned suspension, anda reject outlet for impurities;a scraping device which rotates on an outside of the screen basket about a screen basket axis;foils which scrape along the exterior surface of the screen basket; anda drum having a cylinder surrounding the screen basket, the cylinder being provided with perforations and having a plurality of the foils on its inside facing the screen basket.

2. The device according to claim 1, wherein the screen basket is arranged vertically.

3. The device according to claim 1, wherein the drum rotates about an axis of the screen basket in a direction of rotation.

4. The device according to claim 1, wherein the cylinder is a cage.

5. The device according to claim 1, wherein the foils have a wing profile.

6. The device according to claim 1, wherein a number of the foils per square meter screen basket surface is between 2 and 10.

7. The device according to claim 1, wherein a radial thickness of the drum and the foils is a maximum of about 20% of an exterior diameter of the drum.

8. The device according to claim 1, wherein a radial thickness of the drum and the foils is a maximum of about 10% of an exterior diameter of the drum.

9. The device according to claim 1, wherein the device is for cleaning a fibrous suspension for paper production.

10. A device for cleaning a suspension, comprising: a screen basket having an exterior surface and an interior surface;a housing surrounding the screen basket;a scraping device which rotates on an outside of the screen basket about a screen basket axis;foils which scrape along the exterior surface of the screen basket; anda drum surrounding the screen basket and provided with perforations and a plurality of the foils on its inside, facing the screen basket.

11. The device according to claim 10, wherein the housing comprises: an inflow for suspension to be cleaned,an accepted-stock outlet for cleaned suspension, anda reject outlet for impurities.

12. The device according to claim 10, wherein the drum has a cylinder surrounding the screen basket which includes the perforations and the plurality of the foils.

13. The device according to claim 10, wherein the foils have a wing profile.

14. The device according to claim 10, wherein a number of the foils per square meter screen basket surface is between 2 and 10.

15. The device according to claim 10, wherein a radial thickness of the drum and the foils is a maximum of about 20% of an exterior diameter of the drum.

16. The device according to claim 10, wherein a radial thickness of the drum and the foils is a maximum of about 10% of an exterior diameter of the drum.

17. The device according to claim 10, wherein the perforations are bores or slots distributed over an entire cylinder surface.

18. The device according to claim 10, wherein the drum has a cylinder constructed in a form of a cage from rods running axially or obliquely and from rings running in a helical line such that the perforations are between the rods or rings.

19. The device according to claim 18, wherein a surface of the perforations increases from a bottom upward or vice versa.

20. The device according to claim 10, wherein dimensions of the perforations are larger than a screen opening.

21. A method, comprising: flowing suspension through an annular space formed by a cylinder surrounding a screen basket and a cylindrical housing wall, the cylinder being provided with perforations and having a plurality of the foils on its inside facing the screen basket; andpassing the suspension through perforations in the cylinder to reach the screen basket, whereinan accepted-stock portion of the suspension passes through the screen basket radially inward so that it enters an annular space and flows to an accepted-stock outlet, andrejects remain outside the screen basket and are discharged from a reject outlet.