Liquid purification or separation – Filter – With residue removing means or agitation of liquid
Reexamination Certificate
1998-10-14
2001-02-13
Walker, W. L. (Department: 1723)
Liquid purification or separation
Filter
With residue removing means or agitation of liquid
C210S393000, C210S394000
Reexamination Certificate
active
06186340
ABSTRACT:
BACKGROUND OF THE INVENTION
Certain applications of a liquid filter permit the use of a permanent filter media. However, permanent filter medias require periodic cleaning, as by backwashing, as taught in my U.S. Pat. No. 5,139,670. Where capacity of the filter is relatively large, backwash efficiency must be maximized. Moreover, because an increase in capacity is normally achieved by increasing the area of the filter media, it is extremely important to minimize unit stress on the filter media. When a permanent filter is utilized on a drum filter, assembly of the filter media onto the drum also presents a problem.
SUMMARY OF THE INVENTION
The aforesaid problems are solved, in accordance with a preferred constructed embodiment of the present invention, by a radial outflow drum type filter wherein a flexible permanent filter media is supported by a plurality of bars arranged in a circular array. Backwash is accomplished by a plurality of pencil jets that are directed radially inwardly and downwardly toward the external surface of the filter media to effect backwash of sediment into an internally disposed sediment collector. Edges of the filter media are retained on the drum by a novel sealing system. The sealing system also facilitates assembly of the filter media onto the drum. Rotation of the drum and actuation of the media cleaning jets is controlled by a float switch disposed externally of the filter drum.
More specifically, the rotatable drum filter of the present invention comprises a pair of spaced disks that are connected by a plurality of axially extending bars. The bars are orientated in a circumferentially spaced array radially outwardly of a cylindrical, flexible permanent filter media, for example, a finely woven mono filament polypropylene or dacron cloth belt. If desired, for structural integrity, and additional support of the filter media, a second plurality of circumferentially spaced rods can be employed between the filter discs and spaced radially inwardly of the filter media. In either embodiment the cloth filter media spans the distance between the spaced disks so as to form a fluid permeable cylinder. The edges of the filter media are retained and sealed to the discs by a plurality of circumferentially spaced pins and annular clamping and sealing rings. Contaminated liquid flows into the interior of the filter media cylinder through one of the discs thence radially outwardly through the filter media. The filter discs and the media cylinder rotate intermittently under the control of an external float switch disposed in a clean tank underlying the filter cylinder. Sediment or “cake” is intermittently backwashed from the filter media into an internally disposed collector by pressurized liquid flowing from a series of reciprocating jet type nozzles disposed exteriorly of the filter media cylinder at the top thereof. Thus, backwashing is in the reverse direction from filtration. Flexure of the cloth filter media, which enhances cracking of the sludge cake and backwashing efficiency, is accommodated by the circumferential spacing of the media support bars.
REFERENCES:
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patent: 2765915 (1956-10-01), Nilsson
patent: 3979289 (1976-09-01), Bykowski et al.
patent: 4655937 (1987-04-01), Hendrix
patent: 4869823 (1989-09-01), Otani et al.
patent: 5139670 (1992-08-01), Hirs
patent: 5182008 (1993-01-01), Shelstad
patent: 5549825 (1996-08-01), Barzuza
patent: 5968357 (1999-10-01), Doelle et al.
Lyon P.C.
Ocampo Marianne
Walker W. L.
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