Gravitational separator

Claim 2

A clarifier for use in the gravity separation of suspended particles from a liquid, the clarifier including: a tank for receiving liquid to be clarified, the tank being of rectangular shape in plan and including a bottom having sludge outlet means through which settled sludge can be removed; a gantry supported for movement above the surface of liquid in the tank; gantry drive means adapted to cause the qantry to reciprocate from end to end of the tank in the performance of repeated passes over said liquid surface; a sludge conveyor device which is submerged in liquid in the tank in use at a clearance above the bottom of the tank; support means coupling the conveyor device to the gantry so that the device moves with the gantry and sweeps over the bottom surface of the tank as the gantry performs said repeated passes above the surface of the liquid in the tank; the conveyor device including: a screw which has a helical blade and which is arranged transversely with respect to the direction of movement of the gantry, so as to move sludge which has settled on the bottom of the charifier in said transverse direction towards said outlet means, the screw being positioned with its axis parallel to the bottom of the tank and spaced therefrom by an amount sufficient to provide for clearance between the bottom of the tank and the blade of the screw; means for driving the screw in rotation about said axis; a shroud which extends around part of the circumference of the screw to confine sludge in the region of said helical blade, the shroud being co-extensive with the screw and having an arcuate cross-sectional shape corresponding to the profile of the screw; means coupling the shroud with the screw for free pivotal movement about the longitudinal axis of the screw between two operative positions in each of which the shroud trails with respect to the direction of movement of the gantry so that a leading portion of the screw is exposed for action or sludge in its path; and shroud reversing means located at each end of the clarifier and adapted to engage the shroud as it approaches the reversing means and to restrain the shroud as it moves away from the reversing means each time the gantry reverses its direction of movement in reciprocating from end to end of the tnak, whereby the shroud is caused by said reversing means to automatically move into the other of its two positions.

Claim 3

A clarifier for use in the gravity separation of suspended particles from a liquid, the clarifier including: a tank for receiving a liquid to be clarified, the tank including a bottom surface having sludge outlet means through which settled sludge can be removed, and a side wall defining an upright inner surface; a gantry supported for movement above the surface of liquid in the tank; gantry drive means adapted to cause the gantry to perform repeated passes over said liquid surface; a sludge conveyor device which is submerged in liquid in the tank in use at a clearance above the bottom of the tank; supported means coupling the conveyor device to the gantry so that the device moves with the gantry and sweeps over the bottom surface of the tank as the gantry performs said repeated passes above the surface of the liquid in the tank; the conveyor device including a screw which has a helical blade extending about a longitudinal shaft which defines a longitudinal axis of the screw, the screw being arranged with its axis disposed both transverse to the direction of movement of the gantry, so as to move sludge which has settled on the bottom of the tank towards said outlet means, and parallel to and spaced from the bottom surface of the tank by an amount sufficient to provide for clearance between the bottom of the tank and the blade of the screw; and, means for driving the screw in rotation, said means including a driving wheel carried by the conveyor device for movement therewith and drivably coupled to said longitudinal shaft of the screw, said wheel being arranged in driving contact with one of said surfaces of the tank, whereby the wheel is rotated due to its contact with said surface and drives the said screw as the conveyor device sweeps over the bottom surface of the tank in use.

Claim 4

A clarifier for use in the gravity separation of suspended particles from a liquid, the clarifier including: a tank for receiving a liquid to be clarified, the tank including a bottom surface having sludge outlet means through which settled sludge can be removed, and a side wall defining an upright inner surface; a gantry supported for movement above the surface of liquid in the tank; gantry drive means adapted to cause the gantry to perform repeated passes over said liquid surface; a sludge conveyor device which is submerged in liquid in the tank in use at a clearance above the bottom of the tank; supported means coupling the conveyor device to the gantry so that the device moves with the gantry and sweeps over the bottom surface of the tank as the gantry performs said repeated passes above the surface of the liquid in the tank; the conveyor device including a screw which has a helical blade extending about a longitudinal shaft which defines a longitudinal axis of the screw, the screw being arranged with its axis disposed both transverse to the direction of movement of the gantry, so as to move sludge which has settled on the bottom of the tank towards said outlet means, and parallel to and spaced from the bottom surface of the tank by an amount sufficient to provide for clearance between the bottom of the tank and the blade of the screw; and, means for driving the screw in rotation, said means including a driving wheel carried by the conveyor device for movement therewith and drivably coupled to said longitudinal shaft of the screw, said wheel being arranged in driving contact with one of said surfaces of the tank, whereby the wheel is rotated due to its contact with said surface and drives the said screw as the conveyor device sweeps over the bottom surface of the tank in use.

Claim 5

A clarifier for use in the gravity separation of suspended particles from a liquid, the clarifier including: a tank which is of rectangular shape in plan and which includes a bottom surface having sludge outlet means through which settled sludge can be removed from the tank; a gantry supported for movement above the surface of liquid in the tank; gantry drive means adapted to cause the gantry to reciprocate from end to end of the tank in the performance of repeated passes over said liquid surface; a sludge conveyor device which is submerged in liquid in the tank in use at a clearance above the bottom of the tank; conveyor drive means coupled to the sludge conveyor device; support means coupling the conveyor device to the gantry so that the device moves with the gantry and sweeps over the bottom of the tank as the gantry performs said repeated passes above the surface of the liquid; the conveyor device having at least one sludge-contacting surface which, when the device is in operation, moves in a direction transverse to the direction of movement of the gantry and towards said outlet means; a scum box positioned at one end of the tank; scum skimming means including: at least one skimmer blade which extends transversely with respect to the direction of movement of the gantry; a pair of elongate blade support elements which are spaced longitudinally of said blade and which have outer ends coupled to the blade and inner ends coupled to the gantry for pivotal movement about a horizontal axis so that the blade is movable between a normal skimming position and an elevated position clear of the surface of liquid in said tank; and means biassing the blade into said normal skimming position; the scum box including a ramp positioned in the path of said skimming blade and arranged to lift the blade from said skimming position to said elevated position when the blade approaches said scum box as a result of movement of the gantry towards the box when the clarifier is in use; and, in association with at least one of said elongate blade support elements, locking means for retaining the skimmer blade in said elevated position during movement of the gantry in a direction away from said scum box, said locking means being disposed above the liquid in the clarifier and including: detent means coupled to said elongate blade support element and vertically movable in response to movement of said skimmer blade from said skimming position to said elevated position; a pivotally mounted latch coupled to said gantry and movable between an operative position for engagement with said detent means, and a release position; means biassing the latch into said operative position so as to engage the detent means as the skimmer blade moves to said elevated position in use; and release means coupled to said latch and operable by contact with an abutment at the end of said tank opposite to said scum box to move said latch said release position and allow the skimmer blade to return to its skimming position for return movement of the gantry towards the scum box.

Claim 6

A clarifier for use in the gravity separation of suspended particles from a liquid, the clarifier including: a tank which is of rectangular shape in plan and which includes a bottom surface having sludge outlet means through which settled sludge can be removed from the tank; a gantry supported for movement above the surface of liquid in the tank; gantry drive means adapted to cause the gantry to reciprocate from end to end of the tank in the performance of repeated passes over said liquid surface; a sludge conveyor device which is submerged in liquid in the tank in use at a clearance above the bottom of the tank; conveyor drive means coupled to the sludge conveyor device; support means coupling the conveyor device to the gantry so that the device moves with the gantry and sweeps over the bottom of the tank as the gantry performs said repeated passes above the surface of the liquid; the conveyor device having at least one sludge-contacting surface which, when the device is in operation, moves in a direction transverse to the direction of movement of the gantry and towards said outlet means; a scum box positioned at one end of the tank; scum skimming means including: at least one skimmer blade which extends transversely with respect to the direction of movement of the gantry; a pair of elongate blade support elements which are spaced longitudinally of said blade and which have outer ends coupled to the blade and inner ends coupled to the gantry for pivotal movement about a horizontal axis so that the blade is movable between a normal skimming position and an elevated position clear of the surface of liquid in said tank; and means biassing the blade into said normal skimming position; the scum box including a ramp positioned in the path of said skimming blade and arranged to lift the blade from said skimming position to said elevated position when the blade approaches said scum box as a result of movement of the gantry towards the box when the clarifier is in use; and, in association with at least one of said elongate blade support elements, locking means for retaining the skimmer blade in said elevated position during movement of the gantry in a direction away from said scum box, said locking means being disposed above the liquid in the clarifier and including: detent means coupled to said elongate blade support element and vertically movable in response to movement of said skimmer blade from said skimming position to said elevated position; a pivotally mounted latch coupled to said gantry and movable between an operative position for engagement with said detent means, and a release position; means biassing the latch into said operative position so as to engage the detent means as the skimmer blade moves to said elevated position in use; and release means coupled to said latch and operable by contact with an abutment at the end of said tank opposite to said scum box to move said latch said release position and allow the skimmer blade to return to its skimming position for return movement of the gantry towards the scum box.

Claim 7

A clarifier as claimed in claim 3, wherein the scum skimmer means further comprises: an additional scum skimmer blade, said blades being arranged in parallel positions at respectively opposite sides of said gantry; and a further pair of elongate blade support elements spaced longitudinally of said additional blade and having outer ends coupled to the blade and inner ends coupled to the gantry for pivotal movement about horizontal axis parallel to the pivotal axis of the first mentioned blade support elements, said detent means being coupled to one of said support elements for said additional blade so that both blades can be held in elevated positions by said latch.