High solids filter

A self-cleaning filter assembly for removing solids from an incoming liquid to be filtered, of the kind including

• a housing;
• a cylindrical filter element within said housing;
• inlet means for introducing said liquid to be filtered under pressure into said housing on one side of said filter element;
• filtrate outlet means communicating with the other side of said filter element for withdrawing filtered liquid from said housing, and solids outlet means for withdrawing solids from said housing, wherein the improvement comprises:
• means mounting said filter element within said housing adjacent said inlet means and with a solids collection space between said inlet means and the filtering surface of said filter element and connected with said solids outlet means;
• backwash means for backwashing said filter and thereby for moving solids from the filtering surface of said filter element into said solids collection space;
• said solids outlet means including a solids outlet valve adjustable between a normal operating position and an open position;
• and
• control means responsive to a preselected drop in liquid pressure at said filtrate outlet means with respect to the liquid pressure at said inlet means indicative of an excessive increase in solids concentration in said solids collection space for shifting said solids outlet valve to its open position and thereby for reducing such solids concentration by venting said solids collection space through said solids outlet valve at a high flow rate.

A self-cleaning filter assembly, for removing solids from incoming liquid to be filtered, of the kind including

• a housing;
• a cylindrical filter element within said housing and spaced inward from the peripheral wall of said housing by an annular solids collection space, said housing filter and space having a substantially vertical axis;
• inlet means for introducing the liquid to be filtered under pressure into said housing externally of said filter elemnt;
• a shower assembly rotated coaxially within said filter element, said shower assembly having jet means for expelling backwash liquid outward through the peripheral wall of said filter element to dislodge solids collected on said filter element peripheral wall into said annular solids collection space;
• a filtrate outlet means communicating with the inside of said filter element at the lower end of said housing for withdrawing filtered liquid from said housing;
• and
• solids outlet means through the bottom end of said solids collection space;
• wherein the improvement is comprised by said inlet means being an inlet pipe extending substantially tangentially of said housing to near the top end of said housing and then curving in a decreasing radius spiral about the axis of said housing to communicate radially with said space over a substantial fraction of the circumference of said housing so as to direct liquid spiraling inward toward said filter element in one circumferential direction, said rotation of said shower assembly being in the same circumferential direction as said inlet liquid flow, said solids outlet means comprising a solids outlet pipe extending tangentially from said solids collection space in the same circumferential direction as said liquid inlet flow and shower assembly rotation;
• whereby said circumferentially elongate, inward spiraling inlet pipe, shower assembly rotation and outlet pipe direction all tend to contribute to a centrifugal movement of solids away from the face of the filter element.

In a self-cleaning filter assembly, for removing solids from incoming liquid to be filtered, of the kind including

• a housing;
• a cylindrical filter element within said housing;
• inlet means for introducing said liquid to be filtered under pressure into said housing on the inlet side of said filter element;
• filtrate outlet means communicating with the outlet side of said filter element for withdrawing filtered liquid from said housing;
• and
• solids outlet means for withdrawing solids from said housing, wherein the improvement comprises:
• means mounting said filter element substantially coaxially within said housing, with a solids collection space connected with said solids outlet means;
• a shower assembly disposed coaxially of said filter element, said shower assembly including an eccentric portion having closespaced jets distributed axially therealong in a substantially linear array extending substantially the effective length of said filter element, said jets being aimed toward and lying close to the surface of the filtrate outlet side of said filter element for orbiting with respect thereto, said filter element comprising a filtering surface backed by a rigid backing shell perforated by axially closespaced circumferential rows of holes, each said jet facing outward toward its own said circumferential row of holes to orbit into substantially coaxial alignment with successive holes of its corresponding circumferential row, the spray pattern of each jet being of vertical extent to occupy substantially the full vertical diameter of successively presented holes of its corresponding circumferential row so as to maximize the amount of backwash spray from each jet which passes through each hole to said filtering surface;
• means operatively interposed between said shower assembly and filter element for relatively rotating same;
• means supplying a backwash liquid simultaneously to said jets of said array extending substantially the effective length of said filter element, under pressure exceeding said pressure of said liquid to be filtered for continuously pushing solids off the inlet surface of said filter element in circumferentially advancing fashion.