Liquid purification or separation – Plural distinct separators – Filters
Patent
1992-02-28
1993-07-13
Dawson, Robert A.
Liquid purification or separation
Plural distinct separators
Filters
210346, 210404, 210486, B01D 2939
Patent
active
052270653
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a filter sector for a rotating filter disk in a rotating filter for filtering relatively solid particles from a slurry or a liquid suspension, such as paper pulp. A plurality of such filter sectors, each having the general shape of a truncated sector of a circle, are mounted on a rotatable shaft to form a filter disk, and, generally, a plurality of such filter disks are mounted one after the other on the shaft. The shaft is rotatably supported such that the filter disks are partially submerged in a liquid to be filtered. Upon rotation of the shaft the filter sectors are consecutively submerged in the liquid to perform filtering through a filtering medium carried by each sector and are subsequently raised above the liquid level to perform drying and removal of solids deposited on the filtering medium. The shaft includes channel means for discharging filtrate received from each of the filter sectors.
More particularly, the present invention concerns a filter sector including folded or corrugated means defining between ridges of adjacent folds or corrugations a plurality of channels extending substantially in the radial direction of the filter sector between a radially outer periphery thereof and a radially inner periphery thereof. A filter cloth or other suitable filtering medium is mounted around the folded or corrugated means to be supported by the ridges thereof. Filtering takes place through the filtering medium from both sides of the filter sector such that filtrate enters the substantially radially extending channels and is discharged through the radially inner end of the filter sector. A filter sector of this general kind, including but one folded or corrugated means, is described in SE-B-830069-3 corresponding to U.S. Pat. No. 4,655,920.
This known filter sector suffers from some major drawbacks. Since the folded or corrugated means generally comprises a metal plate, usually of acidproof steel, practically insuperable difficulties are encountered when it comes to folding, particularly since the folds or corrugations are to be located in a fan-like pattern and the filtrate discharge channels formed by the ridges and valleys are to have a gradually increasing height and a gradually increasing cross-section towards the outlet end of the filter sector. Further, filtrate running along the channels is continuously contacting the filtering medium and solids deposited thereon (and possibly partially protruding therethrough) resulting in a considerable loss of flow rate as well as a risk of re-wetting the solids.
Consequently, an object of the present invention is to provide a filter sector of the kind stated, which lends itself to a less troublesome and less expensive manufacture while still being more rigid and stable than existing filter sectors. Another object of the present invention is to provide a filter sector of the kind stated, wherein at least a substantial part of the filtrate is not in contact with the filtering medium during a substantial part of its flow towards the discharge end of the sector. Still another object of the invention is to provide a filter of the kind stated, which enables a higher dry content of the solids deposited on the filtering medium. A further object of the present invention is to provide a filter sector of the kind stated, which enables a high filtering capacity due to a large exposed area over the entire filter sector surface.
These and other objects are accomplished by a filter sector of the kind stated having the characteristic features stated in the appended claims.
In one embodiment of the present invention a filter sector includes three sector parts for receiving and discharging filtrate, viz., a first, a second and a third sector part.
The major portions of the first and the second sector parts are located radially outwards towards the outer periphery of the filter sector and circumferentially on either sides of the third sector part, and are denominated "outer sector parts", whereas the major portion of the third sector part is loca
REFERENCES:
patent: 2591720 (1952-04-01), Peterson
patent: 3485376 (1969-12-01), Peterson et al.
patent: 3917534 (1975-11-01), Moore
patent: 3948779 (1976-04-01), Jackson
patent: 3971722 (1976-07-01), Radford
patent: 4655920 (1987-04-01), Ragnegard
Dawson Robert A.
Kvaerner Eureka A/S
Millard W. L.
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