Sequential swinging precoat removal and renewal system, filter so equipped, and method

Abstract

A precoat renewal system for a filter, such as a disc filter is provided. The renewal system includes a plurality of nozzles coupled to spray piping and valving with each nozzle being positioned for spraying an area of one side of a disc. The nozzles and at least a portion of the spray piping are movable such that the nozzles may be displaced relative to the discs. The nozzles and piping are arranged in groups or zones with each zone covering a specified percentage of the discs in the filter and each zone representing about 40% or less of the surface area of the filter media of the discs in the filter. Each zone is configured such that high pressure fluid may be supplied to that particular zone for removal of a precoat layer on the disc. The system may be configured so that other zones may be concurrently washed with a lower pressure fluid. The zones may be sequentially or otherwise segmentally provided with high pressure fluid until the precoat layers of each respective zone have been removed and renewed. A filter system and a method of treating a precoat layer on a disc-type filter including a plurality of filter discs are also disclosed.

1 . A precoat removal, regeneration and renewal system for a precoat filter having a plurality of filter discs, each disc having a first side and a second side, both sides bearing filter media, the system comprising: 
 a plurality of spray nozzles, each first side and second side of each disc of the plurality having at least one spray nozzle positioned to spray a fluid and effect removal of at least a portion of a layer of precoat material formed on a surface thereof, the plurality of spray nozzles being located on a rising side of the plurality of filter discs as the filter discs rotate about a defined axis, the plurality of nozzles being grouped in a plurality of zones, and    spray piping and at least one valve coupled to the spray nozzles of the plurality and configured for selectively providing fluid to each zone of the plurality of zones.    
     
     
         2 . The precoat removal, regeneration and renewal system of  claim 1 , wherein the at least one valve includes a separate valve associated with each zone.  
     
     
         3 . The precoat removal, regeneration and renewal system of  claim 1 , further including at least one additional valve coupled with the feed piping, wherein the at least one additional valve, in combination with the feed piping, is configured to permit selection between a first flow of a relatively lower pressure fluid and a second flow of a relatively higher pressure fluid to be conveyed to the at least one spray nozzle of an associated zone through the feed piping.  
     
     
         4 . The precoat removal, regeneration and renewal system of  claim 3 , wherein the at least one additional valve includes an additional separate valve associated with each zone.  
     
     
         5 . The precoat removal, regeneration and renewal system of  claim 3 , wherein the feed piping and the at least one additional valve are configured, in combination such that the second flow of a relatively higher pressure fluid may be conveyed to the at least one spray nozzle of at least one zone of the plurality of zones while the first flow of a relatively lower pressure fluid may substantially concurrently be conveyed to at least another zone of the plurality of zones.  
     
     
         6 . The precoat removal, regeneration and renewal system of  claim 3 , wherein the second flow of a relatively higher pressure fluid may be provided at a sufficient pressure to substantially remove a layer of precoat material in its entirety from the first and second sides of the discs, and wherein the first flow of a relatively lower pressure fluid may be provided at a pressure allowing for removal of only an outer portion of the layer of precoat material.  
     
     
         7 . The precoat removal, regeneration and renewal system of  claim 1 , wherein each of the plurality of zones includes a number of spray nozzles sufficient to effect fluid impingement on a predetermined number of first and second sides of the filter discs of the plurality and wherein no zone includes a number of spray nozzles sufficient to effect fluid impingement on more than about 40% of the total surface area of the filter media of the plurality of filter discs.  
     
     
         8 . The precoat removal, regeneration and renewal system of  claim 7 , wherein each of the plurality of zones includes a number of spray nozzles sufficient to effect fluid impingement on between about 15% and 25% of the total surface area of the plurality of filter discs.  
     
     
         9 . The precoat removal, regeneration and renewal system of  claim 1 , wherein the disc filter is configured to provide a pressure differential between interiors of the plurality of filter discs and a space exterior to the filter discs and wherein each zone is configured such that the precoat layer may be removed substantially in its entirety from a predetermined percentage of the surface area of the filter media of the plurality of filter discs without substantially diminishing the pressure differential.  
     
     
         10 . The precoat removal, regeneration and renewal system of  claim 1 , wherein at least a portion of the spray piping is movable and further including a displacement mechanism to move the plurality of spray nozzles and the at least a portion of the spray piping relative to the filter discs.  
     
     
         11 . A precoat filter system comprising: 
 a plurality of filter discs, each disc having a first side and a second side, both sides bearing filter media;    a plurality of spray nozzles, each first side and second side of each disc of the plurality having at least one spray nozzle positioned to spray a fluid and effect removal of at least a portion of a layer of precoat material formed on a surface thereof, the plurality of spray nozzles being located on a rising side of the plurality of filter discs as the filter discs rotate about a defined axis, the plurality of nozzles being grouped in a plurality of zones, and    spray piping and at least one valve coupled to the spray nozzles of the plurality and configured for selectively providing fluid to each zone of the plurality of zones.    
     
     
         12 . The precoat filter system of  claim 11 , wherein the at least one valve includes a separate valve associated with each zone.  
     
     
         13 . The precoat filter system of  claim 1   1 , wherein each of the plurality of zones includes a number of spray nozzles sufficient to effect fluid impingement on a predetermined number of first and second sides of the filter discs of the plurality and wherein no zone includes a number of spray nozzles sufficient to effect fluid impingement on more than about 40% of the total surface area of the filter media of the plurality of filter discs.  
     
     
         14 . The precoat filter system of  claim 13 , wherein each of the plurality of zones includes a number of spray nozzles sufficient to effect fluid impingement on between about 15% and 25% of the total surface area of the plurality of filter discs.  
     
     
         15 . The precoat filter system of  claim 11 , further including at least one additional valve coupled with the feed piping, wherein the at least one additional valve, in combination with the feed piping, is configured to permit selection between a first flow of a relatively lower pressure fluid and a second flow of a relatively higher pressure fluid to be conveyed to the at least one spray nozzle of an associated zone through the feed piping.  
     
     
         16 . A method for treating a precoat layer on a disc-type filter including a plurality of filter discs, the method comprising: 
 substantially completely removing at least a segment the precoat layer from filter media of the filter discs to substantially expose at least a section of the filter media, wherein the substantially completely removing is performed on the rising side of the filter discs as the filter discs are rotated about a defined axis and, wherein the substantially completely removing is performed on no more than about 40% of the total surface area of the filter media of the filter discs of the plurality; and    when not substantially completely removing the precoat layer in its entirety from filter media of a filter disc of the plurality, optionally removing an outer portion of the precoat layer.    
     
     
         17 . The method of  claim 16 , wherein the optional removing of an outer portion of the precoat layer is performed on a substantially continuous basis.  
     
     
         18 . The method of  claim 16 , wherein the optional removing of an outer portion of the precoat layer is performed on a discontinuous basis.  
     
     
         19 . The method of  claim 16 , wherein the optional removing of an outer portion of the precoat layer is performed on a substantially regular, cyclical basis.  
     
     
         20 . The method of  claim 16 , wherein the substantially completely removing is performed on approximately 15% to 25% of the total surface area of the filter media discs of the plurality.