Filter method and apparatus

A filter, comprising relatively movable, vertically superimposed filter shells which define an upper receiver chamber and a lower discharge chamber, a filter medium interposed between the two shells, and the shells having opposed, aligned peripheral surfaces with at least one of said shells carrying a compressible gasket on its peripheral surface for sealing the filter assembly during filtration;

• means for vertically displacing the upper shell (a) to place the shells in adjacent proximity for a filtration cycle, (b) to compress the gasket prior to the initiation of a filtration cycle to an extent greater than that necessary for establishing a liquid-tight seal, and (c) to space the shells from each other subsequent to a filtration cycle;
• an abutment surface vertically spaced from the upper shell;
• and blocking means freely insertable between the upper shell and the abutment surface when the displacement means has compressed the gasket to said greater extent, the vertical dimension of said blocking means being slightly less than the corresponding dimension between said upper shell and the abutment surface when the gasket is compressed;
• the upper shell being slightly displaced away from the lower shell after the blocking means is inserted between the upper shell and the abutment, thereby (a) slightly relaxing the compression on the gasket, (b) placing the blocking means in compression to resist the forces generated within the filter shells during filtration and (c) maintaining the gasket in compression to maintain an essentially water-tight seal around the periphery of the filter shells.

In a method of sealing aligned, separable, liquid conducting shells of a pressure filter having a filter medium therebetween, and opposed aligned peripheral sealing surfaces on each of the shells, and a compressible gasket interposed between the sealing surfaces of said shells, the steps of:

• displacing one of the shells from a first open position spaced from the other shell to a second closed position adjacent the other shell for filtration;
• during the displacement of said one movable shell, compressing the gasket to an extent greater than that necessary to establish an essentially water-tight seal between the sealing surfaces of said filter shell;
• loosely interposing a force bearing member between said movable shell and a fixed abutment surface ;
• flowing contaminated liquid under pressure into an influent chamber defined by one of said shells, flowing the liquid through the filter medium to accumulate contaminants, and receiving clarified liquid from the filter medium in an effluent chamber defined by the other of the shells;
• during initial filtration flow through the filter shell assembly, accommodating movement of the movable shell away from the other shell in response to the internal pressure of the contaminated liquid until the force bearing member is placed in compression, and thereafter utilizing the compression capability of said force bearing member to maintain the movable shell in a filtration position and to maintain the gasket in compression for an essentially water-tight seal between the separable shells;
• terminating liquid flow through the filter shells to relieve the internal pressure on the shells;
• slightly displacing the movable shell toward the other shell against the resistive force of the compressible gasket;
• displacing the force bearing member from its loosely interposed position;
• and displacing the movable shell to a second position spaced from the other shell to accommodate the discharge of accumulated contaminants.

In a method of locking two separable shells of a pressure filter in adjacent proximity for filtration, wherein one of the shells is fixed and the other is movable, wherein a compressible gasket is interposed between the aligned peripheries of the shells for sealing, and a filter medium is interposed between the shells for accumulating contaminants, the steps of:

• (A) displacing the movable shell from a first position spaced from the fixed shell to a second position adjacent the fixed shell for filtration, thereby providing a space between an abutment surface on the movable shell and a fixed abutment surface spaced from the movable shell;
• (B) during the performance of Step (A), compressing the gasket between the peripheries of the two shells to an extent greater than necessary to establish an essentially water-tight seal therebetween, thereby providing additional clearance between the two abutment surfaces;
• (C) inserting a blocking member into the space between the abutment surfaces, with the additional clearance provided by the excessive compression of the gasket facilitating the performance of this step;
• (D) flowing liquid under pressure into a receiver chamber defined by one of the shells, through the filter medium to accumulate contaminants, and into a discharge chamber defined by the other shells;
• (E) during the performance of Step (D), placing the blocking member in compression between the movable shell and the fixed abutment surface to maintain the movable shell adjacent the fixed shell for the filtration cycle, the movable shell being slightly displaced away from the fixed shell to eliminate the clearance provided by the excessive compression, yet being maintained in a filtration position adjacent the fixed filter shell to maintain an essentially water-tight seal compression of the gasket;
• and
• (F) terminating the flow of liquid through the filter assembly.

In a method of pressure filtration by the accretion of solid contaminants on a foraminous filter medium located between separate filter shells, one of the shells being movable in a path toward and away from the other shell, said shells having a compressible gasket sealingly interposed therebetween during filtration, and the pressure of filtration tending to move the one shell in said path toward a fixed abutment interposed in said path, the steps of:

• (1) moving said one shell in said path toward the other shell (a) to seal the shells to one another and (b) to compress said gasket to an extent such that the one shell is spaced from the abutment through a distance "d";
• (2) interposing between the one shell and the abutment a stop member having a dimension "d-x" measured in the path of movement of said one shell;
• (3) accomodating movement of the one shell away from the other shell through the distance "x" so that the stop member contacts both the abutment and the one shell to resist any further movement;
• and
• (4) retaining the gasket under sufficient compression at the spacing between the shells after the movement of step (3) to maintain a seal.

In a method of pressure filtration by the accretion of solid contaminants on a foraminous filter medium clamped between the peripheries of separable filter shells, the clamping edges of said shells having a medium-engaging compressible gasket sealingly interposed therebetween, and the pressure of filtration tending to separate said shells, the steps of:

• (1) separating the shells at the conclusion of a previous filtration cycle (a) to unclamp the filter medium and (b) to accomodate the removal of previously accreted contaminants, the separation of said shells moving one of the shells toward a fixed abutment spaced from the one shell,
• (2) after removal of the contaminants, clamping the shells onto the filter medium under a load greater than that necessary to maintain liquid-tight seal during filtration, said greater load compressing the gasket to an extent greater than that necessary to maintain a seal during filtration under pressure,
• (3) interposing a locking element between the one shell and said fixed abutment while the shells are clamped as defined in step (2),
• (4) retaining the shells in clamped relation by the locking element interposed between the one shell and the fixed abutment, and
• (5) reinitiating filtration under pressure, the locking element (a) resisting any separation of the shells under the pressure of filtration and (b) insuring the compression of the gasket to the extent necessary to maintain the seal during filtration.

In a method of locking two separable shells of a pressure filter in adjacent proximity for filtration, wherein one of the shells is fixed and the other is movable, wherein a compressible gasket is interposed between the aligned peripheries of the shells for sealing, and a filter medium is interposed between the shells for accumulating contaminants, the steps of:

• (A) displacing the movable shell from an open position spaced from the fixed shell to a first closed position adjacent the fixed shell for filtration, and simultaneously spacing an abutment surface on the movable shell through a distance "d" from a fixed abutment surface spaced from the movable shell;
• (B) during the performance of Step (A), compressing the gasket between the peripheries of the two shells to an extent greater than necessary to establish an essentially water-tight seal therebetween;
• (C) loosely interposing a blocking member between the abutment surfaces, the blocking member having a dimension "d-x" interposed between the two abutment surfaces;
• (D) flowing liquid under pressure into a receiver chamber defined by one of the shells, through the filter medium to accumulate contaminants, and into a discharge chamber defined by the other shells;
• (E) during the performance of Step (D), moving the movable shell away from the fixed shell through the distance "x" to tightly interpose the blocking member between the two abutment surfaces and to place the blocking member in compression between the movable shell and the fixed abutment surface to maintain the movable shell adjacent the fixed shell for the filtration cycle, the compressible gasket being under sufficient residual compression to maintain an essentially water-tight seal between the shells.

In a pressure filter assembly having a filter medium between relatively movable, aligned filter shells which respectively define receiver and discharge chambers in the assembly;

• the shells having opposed, aligned peripheral surfaces, with at least one of said shells carrying a compressible gasket on its peripheral surface for sealing the filter assembly during filtration;
• an influent passageway for supplying contaminant-carrying liquid under pressure to the receiver chamber;
• and an effluent passageway interconnected with the discharge chamber for receiving clarified liquid after its passage through the filter medium, upon which contaminants are accreted;
• the improvement of:
• displacement means for relatively displacing the filter shells (a) to place the shells in adjacent proximity for a filtration cycle and (b) to compress the gasket prior to the initiation of a filtration cycle to an extent greater than that necessary to seal the filter assembly;
• a fixed abutment surface spaced from one of said filter shells through a distance "d" when the shells are displaced;
• and blocking means having a dimension "d-x" and freely insertable between said one shell and the abutment surface when the shells are displaced;
• the blocking means accommodating displacement of the one shell away from the other shell through the dimension "x" upon the introduction of liquid under pressure into the filter assembly for a filtration cycle, thereby (a) reducing the compression on the gasket by expansion of the gasket through the dimension "x" while still maintaining the gasket under sufficient compression to maintain an essentially liquid-tight seal between the shells, and (b) interposing the blocking means under compression between the two abutment surfaces to resist any further displacement of the one shell away from the other shell.

In a method of pressure filtration by the accretion of solid contaminants on a foraminous filter medium clamped between the peripheries of separable filter shells, the clamping edges of said shells having a medium-engaging compressible gasket sealingly interposed therebetween, and the pressure of filtration tending to separate said shells, the steps of:

• (1) initially clamping the shells onto the filter medium under a load, (a) capable of compressing the gasket to an extent greater than that necessary to maintain a seal during filtration under pressure, and (b) less than that necessary to prevent separation of the shells during filtration under pressure;
• (2) prior to initiation of filtration, loosely interposing a locking element between one of said shells and a fixed abutment while the shells are clamped under the load as defined in step (2),
• (3) initiating filtration under pressure, thereby separating said shells against the clamping load of step (1), and
• (4) limiting the separation of the shells during the performance of Step (3) and during subsequent filtration under pressure while retaining the gasket compressed sufficiently to maintain a seal by the locking element which is snugly interposed under compression between said one of the shells and said fixed abutment.