Liquid purification or separation – Plural distinct separators – Filters
Patent
1989-02-24
1990-06-26
Spear, Frank
Liquid purification or separation
Plural distinct separators
Filters
210346, 210486, B01D 3326
Patent
active
049369920
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a disk filter including a plurality of rotatable, axially spaced annular filter disks adapted to be partially immersed in a liquid or a suspension to be filtered, each disk comprising a plurality of filter elements which are in communication with axial filtrate conduits arranged at the outer peripheries of the annular disks for discharge of filtrate.
BACKGROUND OF THE INVENTION
A filter of this kind is described in SE-C No. 8305817-2 and in corresponding EP-B1 No. 0160069 and U.S. Pat. No. 4 634 529. The axial filtrate conduits of this filter are produced with re-flow barriers for preventing so-called "backwash", i.e. re-wetting of a filter cake, such as dehydrated fibers, deposited on the filter elements, due to the filtrate from the filtrate conduits running back again to the filter elements.
SUMMARY OF THE INVENTION
The object of the present invention is to improve a filter of the kind discussed hereinabove so that the filtrate flow speed in its axial filtrate conduits is increased to a great extent. Possible re-flow barriers will thus be less essential or can be completely dispensed with.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying drawing, in which
FIG. 1 is a perspective view of a filter rotor, and
FIG. 2 is a section through the rotor on a larger scale, taken in a direction toward its outlet end.
DESCRIPTION OF PREFERRED EMBODIMENT
The filter rotor illustrated in FIG. 1 has at one end a ring 1 with a smooth circumference which is carried by roller bearings (not shown). From the ring 1 there extend substantially axial filtrate conduits 2a, 2b, 2c, etc. which are fastened in the ring and which, at the end of the rotor remote from the ring 1, merge into substantially radially directed filtrate conduits 3a, 3b, 3c, etc. These terminate in a valve means 4, through which the radial filtrate conduits and thereby the corresponding axial filtrate conduits are sequentially placed into communication with a suction discharge system for the filtrate. The axial filtrate conduits are connected by parallel annular filter disk holders 5:1, 5:2, 5:3 . . . 5:11, which carry annular filter disks 6:1, 6:2, 6:3 . . . 6:11. Each filter disk, e.g., the disk 6:1, comprises a plurality of filter elements 6:1a, 6:1b, etc., each of which has a filtrate outlet (not shown) in communication with an axial filtrate conduit via a filter disk holder. In the direction of rotation of the filter rotor indicated by arrow (A), a filter element, e.g., the element 6:1a, communicates vil the filter disk holder 5:1 solely with the succeeding axial filtrate conduit 2a, the filter element 6:1b only with the conduit 2b, etc.
FIG. 2 shows the filter rotor as being immersed in a vessel 7 containing a liquid to be filtered. The liquid surface is denoted by 8. A collection trough extends through all the filter disks. The valve means 4 is so arranged that the flow of filtrate toward it is maintained in each radial filtrate conduit and its associated axial filtrate conduit from the time that a filter element beginning when it is approximately in the position assumed by the filtrate conduit 2f and the element 6:11f shown in FIG. 2. This flow of filtrate is maintained approximately until the given filter element and associated filtrate conduit are in the position assumed by the filtrate conduit 2b and the element 6:11b.
It be important that the filtrate is rapidly led away around the positions assumed by the axial filtrate conduits 2a and 2b, so that it no longer remains in the conduits when these rise further, in order to prevent the risk of it running back again to the associated filter element, which could possibly take place from the conduit 2b to the element 6:11b as well as from the conduit 2c to the element 6:11c in FIG. 2. In accordance with the invention, therefore, the axial filtrate conduits slope towards the outlet end during the critical part of the time they convey the filtrate, namely, within the time just befo
REFERENCES:
patent: 2464223 (1949-03-01), Genter
patent: 4056473 (1977-11-01), Nilsson
patent: 4169794 (1979-10-01), Badino
patent: 4634529 (1987-01-01), Nilsson
patent: 4637876 (1987-01-01), Dosoudil
patent: 4676901 (1987-06-01), Ragnegard
patent: 4678575 (1987-07-01), Frykhult
Drodge Joseph
Spear Frank
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