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1. WO1996039558 - MULTIPLE CONTOUR SCREENING

Publication Number WO/1996/039558
Publication Date 12.12.1996
International Application No. PCT/FI1996/000328
International Filing Date 31.05.1996
Chapter 2 Demand Filed 06.12.1996
IPC
B01D 29/35 2006.01
BPERFORMING OPERATIONS; TRANSPORTING
01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
DSEPARATION
29Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/-B01D27/170;   Filtering elements therefor
11with bag, cage, hose, tube, sleeve or like filtering elements
31Self-supporting filtering elements
35arranged for outward flow filtration
D21D 5/16 2006.01
DTEXTILES; PAPER
21PAPER-MAKING; PRODUCTION OF CELLULOSE
DTREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
5Purification of the pulp suspension by mechanical means; Apparatus therefor
02Straining or screening the pulp
16Cylinders and plates for screens
CPC
B01D 2201/184
BPERFORMING OPERATIONS; TRANSPORTING
01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
DSEPARATION
2201Details relating to filtering apparatus
18Filters characterised by the openings or pores
184Special form, dimension of the openings, pores of the filtering elements
B01D 2201/287
BPERFORMING OPERATIONS; TRANSPORTING
01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
DSEPARATION
2201Details relating to filtering apparatus
28Position of the filtering element
287Filtering elements with a vertical or inclined rotation or symmetry axis
B01D 29/356
BPERFORMING OPERATIONS; TRANSPORTING
01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
DSEPARATION
29Other filters with filtering elements stationary during filtration, e.g. pressure or suction filters, or filtering elements therefor
11with bag, cage, hose, tube, sleeve or like filtering elements
31Self-supporting filtering elements
35arranged for outward flow filtration
356open-ended, the arrival of the mixture to be filtered and the discharge of the concentrated mixture are situated on both opposite sides of the filtering element
B01D 29/86
BPERFORMING OPERATIONS; TRANSPORTING
01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
DSEPARATION
29Other filters with filtering elements stationary during filtration, e.g. pressure or suction filters, or filtering elements therefor
76Handling the filter cake in the filter for purposes other than for regenerating
86Retarding cake deposition on the filter during the filtration period, e.g. using stirrers
D21D 5/16
DTEXTILES; PAPER
21PAPER-MAKING; PRODUCTION OF CELLULOSE
DTREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
5Purification of the pulp suspension by mechanical means; Apparatus therefor
02Straining or screening the pulp
16Cylinders and plates for screens
Applicants
  • CAE SCREENPLATES OY [FI]/[FI] (AllExceptUS)
  • FREJBORG, Frey [FI]/[US] (UsOnly)
Inventors
  • FREJBORG, Frey
Agents
  • TURUN PATENTTITOIMISTO OY
Priority Data
08/469,86706.06.1995US
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) MULTIPLE CONTOUR SCREENING
(FR) TAMIS A SURFACES PROFILEES MULTIPLES
Abstract
(EN)
A screen cylinder or plate with a screening surface (11) for separating accepts from rejects, the surface including a number of parallel macro grooves (22) and a number of parallel micro grooves (24) formed within each macro groove generally transverse to the flow direction. The macro grooves induce shear stress in the reject material preventing it from forming a mat on the screening surface. The micro grooves induce micro turbulence into the pulp at the screening openings (27) improving accepts flow through the openings. Each micro groove within a macro groove is located further away from the accepts surface (12) moving in the flow direction. The contour of each micro groove preferably includes an upstream wall (39), a sloped downstream wall (40), and a depression (41) therebetween. The screening openings are provided in the depression. It is possible to screen with a rejects rate of about 3-10 % at debris removal efficiency of above about 85 %.
(FR)
L'invention concerne une plaque ou un cylindre filtrant présentant une surface filtrante (11) pour séparer des particules acceptées et des particules rejetées, la surface comprenant une pluralité de macro-rainures parallèles (22) et une pluralité de micro-rainures parallèles (24) formées dans chaque macro-rainures, dans une direction généralement perpendiculaire à la direction d'écoulement. Les macro-rainures induisent des contraintes de cisaillement dans les particules rejetées et les empêchent de former un tapis sur la surface du tamis. Les micro-rainures induisent une micro-turbulence dans la pâte au niveau des ouvertures (27) du tamis, ce qui améliore le passage des particules acceptées à travers les ouvertures. Chaque micro-rainure dans la macro-rainure est plus éloignée de la surface d'acceptation (12) quand on se déplace dans la direction d'écoulement. Le contour de chaque micro-rainure comprend de préférence une paroi amont (39), une paroi aval inclinée (40) et une dépression (41) entre les deux. Les ouvertures du tamis sont aménagées dans la dépression. Il est possible d'effectuer un tamisage avec un taux de rejet d'environ 3-10 % pour une efficacité d'élimination des débris supérieure à environ 85 %.
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