Liquid purification or separation – Diverse distinct separators – Including a filter
Patent
1994-08-23
1996-01-02
Upton, Christopher
Liquid purification or separation
Diverse distinct separators
Including a filter
210391, 210400, 210406, B01D 3304
Patent
active
054805449
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a belt filter for removing contaminant from water or other liquids having a viscosity similar to that of water.
A common form of filter comprises a fine woven wire mesh which is static and is used as a gravity filter. The capacity of such a filter is restricted in its liquid handling capacity due to the surface tension that supports the droplets of liquid formed under the wire mesh. The smaller the droplets are the stronger the surface tension and the stronger the surface tension the bigger the resistance to flow through the filter. Also in such a situation the wire mesh will very quickly blind and close off or seriously restrict throughput of liquids to be filtered.
The present invention seeks to improve the water handling capacity of a belt filter by immersing the filter cloth in the liquid to be cleaned thereby removing surface tension, and moving the filter cloth through the contaminated liquid.
Accordingly the present invention provides a liquid filtration apparatus comprising an endless continuously movable filtering medium an advancing length of which medium being immersible in a container of contaminated liquid, driving means to move the filtering medium through the contaminated liquid, means for cleaning containments from the filtering medium and means for removing cleansed liquid above the filtering medium in the region of immersion in the contaminated liquid, where only the area of liquid extraction is submerged below the surface of the contaminated liquid, the filtering medium being shaped in cross-section in the region of immersion of the advancing length of the filtering medium in the contaminated liquid. Preferably the filtering medium comprises a wire mesh cloth belt.
The contaminated liquid container can have an inlet through which contaminated liquid is received and an outlet from which contaminated liquid is discharged and the level of contaminated liquid can be controlled by liquid level sensing means and a moveable weir located upstream of the outlet which functions in dependence of the signal from the liquid level sensing means.
The drive means can comprise two or more rubber covered rollers over which the endless filtering medium passes, one of the rollers being driven by a variable speed drive motor and another roller being adjustable in position to maintain tension in the filtering medium.
Preferably the drive roller is cambered.
The cleansed liquid removal means can comprise a syphon, the syphon including a syphon tube having a generally rectangular mouth in contact with the filtering medium in the contaminated liquid tank.
The filtering medium can comprise a pair of nested fine woven synthetic wire mesh cloth belts both arranged in the form of a dish in the region of immersion of the advancing length of the filtering medium in the contaminated liquid. The two belts can have a common drive roller but separate tensioning rollers.
The filtering apparatus can also include a centrifugal separator arranged to receive the cleansed liquid and to return rejected liquid to the contaminated liquid. The rollers can be supported above and clear of the contaminated liquid level, and the advancing length of the filtering medium is depressed by the mouth of the syphon, the syphon mouth being less in width than the filtering medium, thereby forcing the edges of the filtering medium to turn up and remain above the level of the contaminated liquid, the edges of the filtering medium being maintained in this position by contact straps on the sides of the container.
The mouth of the syphon tube can be provided with support bars in contact with the filtering medium, the support bars extending transversely to the direction of travel of the filtering medium.
The syphon has a drop leg terminating in a valve which can be controlled either by a ram and/or by a float.
The syphon includes a priming valve which allows clean water to be admitted into the syphon.
The cleansing means of the filtering medium can comprise a static array of water jets extending across the width of the filte
REFERENCES:
patent: 636762 (1899-11-01), Conley
patent: 1780954 (1930-11-01), Tompkins
patent: 2619232 (1952-11-01), Parsons et al.
patent: 2963161 (1960-12-01), Holland
patent: 4285816 (1981-08-01), Lee
patent: 5006233 (1991-04-01), Muisener
patent: 5202034 (1993-04-01), Martel, Jr.
Profit Improvement and Engineering Limited
Upton Christopher
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