Patent Publication Number: US-2022233976-A1

Title: Backflush filter assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims benefit of priority to U.S. Application No. 63/142,622 filed on Jan. 28, 2021, the entire disclosure of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The invention generally relates to a backflush filter assembly configured to remove particulates and other contaminants from fluids, particularly to a backflush filter assembly having replaceable bag-type filter elements. 
     SUMMARY 
     According to one or more aspects of the present disclosure, a filter assembly includes an inner filter basket comprising an elongated tubular portion having a first open end and a first closed end, the tubular portion defining a plurality of perforations therethrough. An outer surface of the tubular portion is seamless. A first annular brim extends outwardly from the open end of the tubular portion. The filter assembly also includes an outer filter basket having a second open end in which the inner filter basket is received. A second annular brim extends outwardly from the second open end of the outer filter basket. The first and second brims are configured to retain a bag filter between the inner filter basket and the outer filter basket. 
     In one or more embodiments of the filter assembly according to the previous paragraph, the tubular portion of the inner filter basket has an unperforated strip extending from the open end to the closed end. 
     In one or more embodiments of the filter assembly according to any one of the previous paragraphs, the filter assembly further includes a fabric filter bag and a flange defining an elastomeric annular ring surrounding an opening in the fabric filter bag. 
     In one or more embodiments of the filter assembly according to any one of the previous paragraphs, the flange and the annular ring are integrally formed of the same elastomeric material. 
     In one or more embodiments of the filter assembly according to any one of the previous paragraphs, the flange has a cylindrical portion to which the fabric filter bag is attached. 
     In one or more embodiments of the filter assembly according to any one of the previous paragraphs, the flange has a frustoconical section between the cylindrical portion and the annular ring. 
     In one or more embodiments of the filter assembly according to any one of the previous paragraphs, an outer edge of the flange has a generally circular cross section, and a dimeter of the outer edge is greater than a thickness of the annular ring. 
     According to one or more aspects of the present disclosure, a filter assembly includes a fabric filter bag and a flange defining an elastomeric annular ring surrounding an opening in the fabric filter bag. The filter assembly may also include any of the features of any one of the previous paragraphs. 
     In one or more embodiments of the filter assembly according to the previous paragraph, the flange and the annular ring are integrally formed of the same elastomeric material. 
     In one or more embodiments of the filter assembly according to any one of the previous paragraphs, the flange has a cylindrical portion to which the fabric filter bag is attached. 
     In one or more embodiments of the filter assembly according to any one of the previous paragraphs, the flange has a frustoconical section between the cylindrical portion and the annular ring. 
     In one or more embodiments of the filter assembly according to any one of the previous paragraphs, an outer edge of the flange has a generally circular cross section and wherein a dimeter of the outer edge is greater than a thickness of the annular ring. 
     According to one or more aspects of the present disclosure, a filter assembly includes a pressure vessel having a cover movable from a closed position in which the vessel is sealed to an open position that allows access to the interior of the pressure vessel, a plurality of filter elements arranged within the pressure vessel, and a manifold of pneumatic tubes integrated into the cover and movable with the cover. One pneumatic tube of the manifold of pneumatic tubes is positioned over an open end of each filter element in the plurality of filter elements when the cover is in the closed position. The filter assembly may also include any of the features of any one of the previous paragraphs. 
     In one or more embodiments of the filter assembly according to the previous paragraph, the manifold of pneumatic tubes is configured to forcibly evacuate a fluid from the pressure vessel by delivering a compressed gas to each filter element in the plurality of filter elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described, by way of example with reference to the accompanying drawings, in which: 
         FIGS. 1A and 1B  are top and side views of a filter assembly according to some embodiments; 
         FIGS. 2A and 2B  are top and side views of the filter assembly of  FIGS. 1A and 1B  with an alternative lid opening mechanism according to some embodiments; 
         FIGS. 3A and 3B  are top and side views of another filter assembly according to some embodiments; 
         FIG. 4  is a perspective view of a filter element according to some embodiments; 
         FIGS. 5A-5C  are side, end, and perspective views of the inner filter basket of the filter element of  FIG. 4  according to some embodiments; 
         FIG. 6  is a close-up view of the inner filter basket of  FIG. 4  according to some embodiments; 
         FIG. 7  is a drawing of an outer filter basket of the filter element of  FIG. 4  according to some embodiments; 
         FIGS. 8A and 8B  perspective views of a fabric filter bag of the filter element of  FIG. 4  according to some embodiments; 
         FIGS. 9A-9C  are front, side, and rear views of a filter bag flange of the fabric filter bag of  FIGS. 8A and 8B  according to some embodiments; 
         FIG. 10  is a perspective rear view of the filter bag flange of  FIGS. 9A-9C  according to some embodiments; 
         FIG. 11  is a front view of the filter bag flange of  FIGS. 9A-9C  according to some embodiments; and 
         FIG. 12  is another perspective rear view of the filter bag flange of  FIGS. 9A-9C  according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     A backwash filter assembly  10  is presented herein and is illustrated in  FIGS. 1A-3B . The filter system has a pressure vessel  12  with a cover  14  that is movable to allow access to one or more replaceable filter elements  16  shown in  FIG. 4  that have a fabric filter bag  18  retained within an inner filter basket  20  and outer filter basket  22 .  FIGS. 1A and 1B  show a filter assembly  10  having a spring assisted cover  14  while  FIGS. 2A and 2B  show a filter assembly  10  with a counterweight assisted cover. Other embodiments of the filter assembly may have a single filter element, two filter elements, or more than four filter elements. Yet other embodiments of the filter assembly may also have multiple pressure vessels, each having one or more filter elements. 
     These filter elements  16  are configured to remove particulates or other contaminants from a pressurized fluid that is delivered into a fluid inlet  24  of the filter assembly and discharged from a fluid outlet of the filter assembly. The filter assembly also includes a pneumatic inlet  28  and a drain outlet  30 . The pneumatic inlet  28  and a drain outlet  30  are arranged opposite to the fluid inlet  24  and the fluid outlet  26 . To backflush the filter assembly, valves (not shown) controlling the fluid inlet  24  and fluid outlet  26  are closed and valves controlling the pneumatic inlet  28  and drain outlet  30  are opened. The pneumatic inlet  28  provides a stream of pressurized gas, such as compressed air, flowing in a direction opposite of the normal fluid flow through the filter elements  16 . This compressed air stream removes particulates on the surface of the filter elements  16  and forces the particulates and remaining fluid in the filter assembly  10  through the drain outlet  30  for disposal. The pneumatic inlet  28  and drain outlet  30  valves are then closed and the fluid inlet  24  and fluid outlet  26  valves are opened to resume normal filtering operation. 
     As best shown in  FIGS. 1A and 1B , the moveable cover  14  of the filter assembly  10  includes a manifold  32  of pneumatic tubes that, when the cover  14  is closed, are positioned over or within the open ends of each of the filter elements  16 . These pneumatic tubes are configured to deliver the blast of compressed air to each of the filter elements  16  to backflush the fabric filter bags  18 . The integration of the manifold  32  into the moveable cover  14  greatly simplifies the procedures for maintaining and replacing the fabric filter bags  18  in the filter elements  16  since the pneumatic tubes swing away from the filter elements when the cover is opened and do not need to be disassembled to gain access to the fabric filter bags. 
     In alternative embodiments, the filter assembly may be configured for a fluid backwashing of the filter elements rather than the pneumatic backflush described above. 
     The inner filter baskets  20  shown in  FIGS. 5 and 6  are made from a sheet of perforated metal, e.g., stainless steel. The sheet is rolled into a tube and the edges  36  are welded together and the weld is then machined to remove any raised seam on the outer surface of the inner basket. This provides an inner filter basket  20  that is much easier to place in a fabric filter bag  18  because it eliminates potential sources of snags formed by a raised welded, crimped, or overlapping seam that make inserting the inner filter basket  20  into the fabric filter bag  18  more difficult and may damage the fabric filter bag  18 . The side walls  34  of the inner filter basket are at least 3 mm (0.125 in) thick and do not require inner stiffening rings as previous inner filter basket designs did. The shape of the inner filter basket  20  is preferably generally cylindrical, but alternatively it may have a frustoconical shape. 
     The outer filter basket  22  shown in  FIG. 7  has wire loops  40  that are retained by flat metal bands  42  on the outside of the wire loops rather than round metal rings. 
     The fabric filter bag  18  shown in  FIGS. 8A and 8B  has a collar or flange  38  shown in  FIGS. 9A-12 . The flange  38  is located at the open end of the fabric filter bag  18  and is made of an elastomeric rubber, e.g., EPDM or FKM material. Other elastomeric or polymeric materials may also be used, mainly depending on the material requirements of the fluid to be filtered. The flange  38  is sandwiched between metal top brims  44 ,  46  of the inner and outer filter baskets as shown in  FIGS. 3A and 3B . The flange  38  has an O-ring  48  that is integrally formed on an outer edge of the flange  38  that is configured to seal the metal top brim  44  of the inner filter basket  20  to the metal top brim  46  of the outer filter basket  22 . The O-ring  48  at least partially seals the flange  38  to the inner and outer basket brims  44 ,  46  to help reduce bypass of fluid around the filter elements  16  when the filter is in operation. The O-ring  48  may be integrally formed with the flange  38  and made of the same elastomeric material. Alternatively, the O-ring  48  may be formed of a different elastomeric material than the flange  38  that has a different durometer value than the flange material using a two-shot molding process. The open end of the fabric filter bag  18  is attached to a cylindrical neck  50  extending from the flange  38 , for example by being sewn to the neck of the flange. 
     The cover  14  may further include a plurality of hold down features  52  integrated with and extending from an inner surface of the cover  14  that contacts the metal top brims  44  of the inner filter baskets  20  when the cover  14  is closed. These hold down features  52  retain the filter elements  16  in their proper location during operation of the filter assembly  10 . Each of the hold down features  52  include a stem  54  having a fixed end attached to the cover  14  and a free end defining a foot  56  that contacts the metal top brim  44  of the inner filter basket  20 . The stem  54  may have a cylindrical shape and the foot  56  may have a disk shape with a diameter that is larger than the stem  54 . Each filter assembly  10  may be held in place by two or more hold down features  52 . The hold down features  52  may be arranged such that one hold down feature  52  may contact the metal top brim  44  of more than one filter assembly  10 . These hold down features  52  provide the benefit of eliminating the need to loosen and/or remove threaded fasteners that may be used to individually secure the filter assemblies as was implemented in prior filter designs in order to remove or replace the filter assemblies. 
     While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to configure a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments and are by no means limiting and are merely prototypical embodiments. 
     Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the following claims, along with the full scope of equivalents to which such claims are entitled. 
     As used herein, ‘one or more’ includes a function being performed by one element, a function being performed by more than one element, e.g., in a distributed fashion, several functions being performed by one element, several functions being performed by several elements, or any combination of the above. 
     It will also be understood that, although the terms first, second, etc. are, in some instances, used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first contact could be termed a second contact, and, similarly, a second contact could be termed a first contact, without departing from the scope of the various described embodiments. The first contact and the second contact are both contacts, but they are not the same contact. 
     The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses all possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     As used herein, the term “if” is, optionally, construed to mean “when” or “upon” or “in response to determining” or “in response to detecting,” depending on the context. Similarly, the phrase “if it is determined” or “if [a stated condition or event] is detected” is, optionally, construed to mean “upon determining” or “in response to determining” or “upon detecting [the stated condition or event]” or “in response to detecting [the stated condition or event],” depending on the context. 
     Additionally, while terms of ordinance or orientation may be used herein these elements should not be limited by these terms. All terms of ordinance or orientation, unless stated otherwise, are used for purposes distinguishing one element from another, and do not denote any particular order, order of operations, direction or orientation unless stated otherwise.