Liquid purification or separation – Filter – Movable medium
Reexamination Certificate
1998-12-23
2001-02-20
Lithgow, Thomas M. (Department: 1724)
Liquid purification or separation
Filter
Movable medium
C210S401000, C210S393000
Reexamination Certificate
active
06189703
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to filtration apparatus, and more particularly to an improved endless media filtration system which utilizes gravity liquid filtration.
BACKGROUND OF THE INVENTION
Gravity-type filtration systems have been used for a number of years to filter particulate from liquids. In general, particulate laden liquid is spread across the width of filter media such that the liquid flows through the media while the particulate is caught within the media to form a cake. As the cake builds, liquid flow is restricted and the fluid level rises on top of the caked particulate to form a pool. Once the fluid level in the pool reaches a predetermined height, the apparatus will shift the media so that liquid again flows across an unobstructed portion of the media.
While these gravity liquid filtration devices have been known for some time, they still suffer several problems. First, prior art filtration systems have utilized a supply of filter media on a reel, which is fed through the filter system, and then cleaned and wrapped on another reel for reuse, or discarded. In order to avoid these problems, an endless filtration system is desirable, which utilizes an endless, continuous loop belt of filtration media which is initially utilized for filtering, washed, and then returned for reuse in the same system.
Because the use of an endless media continuous loop belt requires that one flight of the belt return under the filtering pool, it is desirable to redirect liquid flow from the filtering pool to avoid contamination of the clean fluid.
Another problem with existing endless loop filtration systems is in the cleaning of the filter media.
Finally, endless filter media filtration systems are more prone to sliding or dislodgment of the filter media belt from the carrier belt. In addition, the filter media belt can become wrinkled, which reduces the filtering capacity of the filter media.
SUMMARY OF THE INVENTION
The endless media filtration system of the present invention includes a housing with a pool forming assembly mounted between a pair of side walls. The pool forming assembly includes a central shaft with two spaced-apart containment discs rotatably mounted on the shaft between the side walls. An endless loop filter media belt is supported on an endless loop carrier belt and includes an upper run which is pressed against the peripheral edges of the discs to form a generally semicircular shaped pool along bottom arcs of the discs. A separation pan is located between upper and lower runs of the carrier belt to direct filtered liquid to one side of the carrier belt and out the bottom of the housing. A backwash assembly includes a first spray rod spraying air through the filter media, a second spray rod spraying water through the filter media, and a third spray rod spraying air through the filter media after the filter media has passed under the second spray rod. The spray rods are oriented on the inward side of the filter belt and spray through the filter belt to remove particulate therefrom. A pair of freely rotatable tracking wheels engage the filter media belt and stretch it taut between the tracking wheels to remove wrinkles from the media belt. The media belt is attached to the carrier belt with a rod wrapped in one end of the media belt and tamped into a groove in one link of the carrier belt. The second end of the media belt is wrapped around a second rod, overlapped over the first rod, and tamped into a groove in an adjacent link of the carrier belt.
It is therefore a general object of the present invention to provide an improved endless filter media filtration apparatus.
Another object is to provide a gravity liquid filtration apparatus which directs clean fluid away from the clean flight of the filter media belt.
Yet another object of the present invention is to provide an improved backwash system for cleaning the endless loop filter media belt.
Still another object is to provide a gravity filtration system which prevents wrinkling of the filter media belt, and enhances the retention of the belt on the carrier belt.
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Bell, III Caleb N.
Dooley, Jr. John P.
Hood, Sr. John D.
Kiely Harry A.
Moore Cecelia D.
Lithgow Thomas M.
Thomte Dennis L.
Zarley McKee Thomte Voorhees & Sease
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