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1. WO1996004421 - METHOD AND APPARATUS FOR SCREENING A FIBER SUSPENSION

Publication Number WO/1996/004421
Publication Date 15.02.1996
International Application No. PCT/FI1995/000407
International Filing Date 28.07.1995
Chapter 2 Demand Filed 29.02.1996
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 5/02 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
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
B01D 29/908
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
88having feed or discharge devices
90for feeding
908provoking a tangential stream
D21D 5/026
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
023Stationary screen-drums
026with rotating cleaning foils
Applicants
  • CAE SCREENPLATES OY [FI/FI]; Kiertotie 27 FIN-78300 Varkaus, FI (AllExceptUS)
  • AALTONEN, Frank [FI/NL]; NL (UsOnly)
  • FREJBORG, Frey [FI/US]; US (UsOnly)
Inventors
  • AALTONEN, Frank; NL
  • FREJBORG, Frey; US
Agents
  • TURUN PATENTTITOIMISTO OY; P.O. Box 99 FIN-20521 Turku, FI
Priority Data
08/286,44004.08.1994US
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) METHOD AND APPARATUS FOR SCREENING A FIBER SUSPENSION
(FR) PROCEDE ET APPAREIL DE CRIBLAGE DE FIBRES EN SUSPENSION
Abstract
(EN)
The differences in performance of a screening cylinder during screening of a fiber suspension (e.g. low consistency paper pulp) at the inlet end compared to the reject end is accommodated by constructing the feed side surface of the screening cylinder so that it induces greater turbulence in the vicinity of the screen cylinder surface adjacent the reject end of the screen than adjacent the inlet end. Typically this increase in turbulence is at least about 10 % (preferably at least about 40 %, and typically greater than 100 %). The turbulence increase can be provided by a substantially smooth screening medium surface at the inlet end and a contoured screening medium surface adjacent the reject end, or by first and second contoured surfaces of different aggressiveness. Contoured surfaces typically include grooves, and variables that may be changed to affect the turbulence, include the depth of the grooves, the angle of inclination of the downstream wall of the grooves, the spacing between the grooves, the radius of curvature of the opening (holes or slots) edges, the frequency of openings in grooves, and the dimensions of the openings (holes or slots) in the grooves. The screen cylinder is mounted in a pressure screen housing.
(FR)
Les différences de rendement d'un cylindre de criblage effectuant le criblage d'une suspension de fibres (par exemple de la pâte de papier de faible consistance) entre l'extrémité d'entrée et par rapport à l'extrémité de sortie sont adaptées par la construction de la surface d'admission du cylindre de criblage de telle sorte qu'une turbulence plus grande soit créée au voisinage de la surface contiguë à l'extrémité de sortie du crible qu'au voisinage de l'extrémité d'admission. Généralement, cette augmentation des turbulences est d'au moins 10 % environ (de préférence d'au moins 40 % environ et, généralement supérieure à 100 %). Cette augmentation des turbulences peut être obtenue grâce à une surface du milieu de criblage essentiellement lisse à l'extrémité d'admission et une surface du milieu de criblage relativement tortueuse à l'extrémité de sortie ou bien au moyen de surfaces dont la première et la seconde présentent des reliefs d'une aggressivité différente. Ces surfaces en relief comportent essentiellement des rainures, tandis que les éléments modifiables pour influer sur les turbulences sont la profondeur des rainures, l'angle d'inclinaison de la paroi de ces rainures en aval, l'espacement de ces rainures, le rayon de courbure des rebords d'ouverture (orifices ou fentes), la fréquence des ouvertures dans les rainures et les dimensions des ouvertures (orifices ou fentes) dans les rainures. Le cylindre de criblage est monté dans un boîtier de criblage pressurisé.
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