Sludge tank with self-cleaning screen and screen for use therein

Claim 2

Filtering apparatus comprising a tank having a first compartment adapted to contain a liquid suspension from which suspended matter is to be removed, a second compartment adapted to contain clarified liquid and a filter member between said two compartments, means for supplying suspensions to be clarified to said first compartment, means for removing clarified liquid from said second compartment, movable filter cleaning means having a series of filter-engaging members in said first compartment and means for driving said filter cleaning means to cause said filter-engaging members to continuously wipe the filtering surface of said filter member, said filter member being mounted on the bottom of said tank for swinging motion toward or away from said filter cleaning means and being normally positioned to lean against the filter-engaging members of said filter cleaning means.

Claim 3

Apparatus according to claim 1 wherein the filter member leans against the filter engaging members at an angle of 5* to 30* from the vertical.

Claim 4

Apparatus for removing relatively coarse objects from a liquid in which they are suspended comprising a sludge tank having a first compartment with an outwardly sloping end wall, adapted to contain a suspension from which suspended Objects are to be removed, a second compartment adapted to contain clarified liquid and a filter member between said two compartments, means for supplying suspension to be clarified to said first compartment, means for removing filtrate from said second compartment, an endless conveyor having spaced transverse flights and positioned partially within said first compartment, said conveyor having a first course adjacent to a filtering surface of said filter member, a second course adjacent to the bottom of said first compartment and a third course adjacent to said sloping end wall, means for driving said conveyor to cause the flights thereof to wipe the adjacent surface of said filter member then, move along the bottom of said tank and then move along said sloping end wall to remove from said first compartment objects separated from said suspension, said filter member being mounted on the bottom of said tank for swinging motion toward and away from said conveyor and being normally positioned to lean against the flights of said first course of said conveyor whereby objects accumulating on the filtering surface of said filter member are continuously removed therefrom by said conveyor flights.

Claim 5

Apparatus for removing relatively coarse objects from a liquid in which they are suspended comprising a sludge tank having a first compartment with an outwardly sloping end wall, adapted to contain a suspension from which suspended Objects are to be removed, a second compartment adapted to contain clarified liquid and a filter member between said two compartments, means for supplying suspension to be clarified to said first compartment, means for removing filtrate from said second compartment, an endless conveyor having spaced transverse flights and positioned partially within said first compartment, said conveyor having a first course adjacent to a filtering surface of said filter member, a second course adjacent to the bottom of said first compartment and a third course adjacent to said sloping end wall, means for driving said conveyor to cause the flights thereof to wipe the adjacent surface of said filter member then, move along the bottom of said tank and then move along said sloping end wall to remove from said first compartment objects separated from said suspension, said filter member being mounted on the bottom of said tank for swinging motion toward and away from said conveyor and being normally positioned to lean against the flights of said first course of said conveyor whereby objects accumulating on the filtering surface of said filter member are continuously removed therefrom by said conveyor flights.

Claim 6

Apparatus according to claim 3 wherein said filter member rests on the bottom of said filter tank without being connected thereto.

Claim 7

Apparatus according to claim 3 wherein the filter member and adjacent course of said conveyor are arranged at an angle 5* to 30* from the vertical.

Claim 8

Apparatus according to claim 3 wherein the filtering surface of said filter member comprises a series of approximately vertically arranged strips closely spaced to prevent said objects from passing therethrough and wherein the strips forming said filtering surface are arranged at a small angle with respect to the longitudinal dimension of the screen to equalize wear of the flights of said conveyor.

Claim 9

Apparatus according to claim 6 and wherein the small angle is of a magnitude such that the bottoms of said filtering strips are laterally displaced in respect to the tops of said filtering strips by an amount substantially equal to the distance between the centers of adjacent filtering strips.

Claim 10

Apparatus according to claim 7 wherein said screen is formed of two or more sections and the strips of adjacent sections are arranged at diverging angles whereby they form a herringbone pattern.