Pressure screen and method for dilution for a pressure screen

Abstract

A method for dilution for a pressure screen comprising a rotor rotating inside a screen a distance to the screen, includes supplying feeding stock into a screening zone formed in the spacing between the rotor and the screen with some of the feeding stock passing through the screen into an accept area to become accept, and the remaining feeding stock discharged into a reject area as reject flow. The amount of the dilution water added into the reject flow is 0.8 to 3.5 times the amount of the reject flow by volume. Additionally, a pressure screen comprises a dilution water adding apparatus adapted to add dilution water directly into the reject area of the pressure screen, wherein the amount of the dilution water added into the reject flow is 0.8 to 3.5 times of the amount of the reject flow by volume.

Claims

1. A method for dilution for a pressure screen having a rotor rotating inside a screen with spacing between the screen and rotor, the spacing defining a screening zone into which feeding stock is supplied, with a portion of feeding stock passing through the screen into an accept area and becoming accept, and the remaining feeding stock discharged into a reject area as reject flow, comprising adding dilution water directly into the reject area in an amount equal to 0.8 to 3.5 times of the amount of the reject flow, wherein the rotor comprises a plurality of foils having one or more ribs on a front and a rear side thereof to enhance the distribution of the dilution water in the screening zone.

2. The method according to claim 1, wherein the amount of the dilution water added into the reject area is 1.6 to 2.2 times the amount of the reject flow.

3. A pressure screen for separating a feeding stock into an accept portion and a reject portion, comprising one or more rotors inside a screen with spacing between the screen and rotor, the spacing defining a screening zone into which feeding stock is supplied; and a dilution water adding apparatus configured for adding dilution water directly into the reject area of the pressure screen, wherein at least one of the one or more rotors comprises a plurality of foils having one or more ribs on a front and a rear side thereof to enhance the distribution of the dilution water in the screening zone, and the amount of the dilution water added into the reject flow is 0.8 to 3.5 times the amount of the reject flow.

4. The pressure screen according to claim 3, wherein the amount of the dilution water added into the reject flow is 1.6 to 2.2 times the amount of the reject flow.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically shows a section of a pressure screen with dilution water being added into its reject area.

(2) FIG. 2 schematically shows a section of a pressure screen with dilution water being added into its screening zone via certain designed pipelines.

(3) FIGS. 3A, 3B and 3C schematically show the front and back side of the foils for use within the disclosed embodiments and a rotor with foils.

DETAILED DESCRIPTION

(4) As shown in in the section of the pressure screen 100 of FIG. 1, the dilution water D is still added into the reject area 20 of the pressure screen 100, similar to known methods and systems, however, the amount of the dilution water D added into the reject flow R is 0.8 to 3.5 times of the amount of the reject flow R via a dilution water adding apparatus adapted to do so (not shown).

(5) As shown in FIG. 1, a rotor 40 rotates inside the screen 60 spaced from the screen 60 a distance. Feeding stock F is supplied into a screening zone 10 defined by the spacing between the rotor 40 and the screen 60. Some feeding stock F passes through the screen 60 into the accept area 30 and becomes accept A, and the remaining feeding stock F is discharged into a reject area 20 as reject flow R.

(6) In this embodiment, pipelines like those shown as reference numeral 80 in prior art system of FIG. 2 for supplying dilution water D into the screening zone 10 are omitted. However, with the inventive embodiments that include the disclosed rotor, the same or even better screening effects are surprisingly obtained at lower energy consumption levels as compared with conventional structures that utilize conventional rotors which operate like the systems shown in FIG. 1 or FIG. 2.

(7) As can be seen from the exemplary systems shown in FIGS. 1 and 2, foils 70 can be provided on the rotor 40 to improve the flow condition in the screening zone 10. With reference to FIG. 3, in the disclosed system and method, ribs 50 or similar protruding structures are provided on the front and rears side of the foils 70 which enhance distribution of the dilution water D in the screening zone 10. The foils 70 with ribs 50 may be employed within a variety of pressure screen systems, including without limitation those shown generally in FIGS. 1 and 2, for improving flow conditions thereof.

(8) The above discloses non-limiting preferable embodiments of this invention. Those skilled in the art can make adaptations and applications according to these teachings, and such adaptations and applications will be within the spirit and scope of this invention disclosed herein. Therefore, it will be understood that the specific embodiments do not define the spirit and scope of this invention, which is defined by the claims.

REFERENCE NUMBER LIST

(9) 10 Screening Zone 20 Reject area 30 Accept area 40 Rotor 50 Rib 60 Screen 70 Foil 100 Pressure screen 200 Pressure screen F Feeding stock A Accept R Reject D Dilution water