Abstract:
A filter tube frame for use with a filter bag house. The filter tube frame includes an end cap having a pivotable handle attached thereto to facilitate removal of the tube frame from the bag house. The handle includes a lever surface adapted to engage a tube sheet surface, thus, during use, providing a force to urge the end cap away from the tube sheet and unseat the filter tube frame from the tube sheet.

Description:
FIELD OF THE INVENTION 
   The present invention relates to bag house dust collectors. It particularly concerns a filter collar or tube frame flange for a bag filter, in bag houses. The disclosure also concerns methods of use. 
   BACKGROUND OF THE INVENTION 
   Bag house dust collectors are generally used to filter particulate material from industrial off gases, before the gases are vented or cycled. The arrangements generally include flexible filter bags supported within the construction. The filter bags are generally secured to a tube sheet, which separates the clean air side from the dirty air side of the filter system or collector. A filter cage or filter tube frame, which has a collar at one end, secures the bag to the tube sheet. The cage or frame also keeps the bag from collapsing and keeps the bag generally steady in the air flow streams. 
   Large industrial bag house dust collectors may include hundreds of filter tubes and bags therein. These bags must occasionally be removed from the tube sheet, for example, for maintenance or replacement. In order to remove the bag and the filter tube frame from the tube sheet, the collar and bag must be unseated or unsealed from the tube sheet and then the bag and frame must be lifted out of the aperture in which the bag and frame are seated; this is typically done by the operator reaching at least partially into the bag and frame in order to gain a secure grip. The force needed to unseat and remove the bag and filter tube frame from the tube sheet can be 30 to 45 pounds force. 
   SUMMARY OF THE INVENTION 
   According to the present invention, a filter tube frame for use with a bag filter is provided. The filter tube frame includes a handle to facilitate the removal of the tube frame and bag filter from a tube sheet, when operably mounted in a tube sheet. The handle provides a sturdy gripping surface. Additionally, the handle provides a mechanical advantage when removing the filter tube frame from the tube sheet. The mechanical advantage decreases the actual force needed by the operator to remove the bag and filter tube frame. 
   The handle has a body that defines the gripping surface and a distal end at each end of the handle. At least one of the distal ends provides a lever surface or arm that engages against the tube sheet. The lever surface of the distal end facilitates removal of the filter tube frame from the tube sheet by providing a force that urges the tube frame away from the tube sheet. The handle design of the present invention can decrease the conventional force needed to release the compression fit and remove the filter tube frame and bag from the tube sheet from 30 to 45 pounds force to about 6 to 10 pounds force. 
   In one particular embodiment, a handle having two distal ends with lever surfaces, the distal ends extending about 0.812 inch from the pivot points, decreases the force needed from 30 pounds to about 6.6 pounds force, and decreases a needed force of 45 pounds to about 9.9 pounds force. 
   In one particular embodiment, the present invention is directed to a filter tube frame having a first end and a second opposite end, an end cap at the first end, the end cap having a top surface and a lower edge, and a handle pivotably mounted on the end cap. The end cap has a body and a first end, and a pivot point located on the handle between the body and the first end. The end is preferably a lever surface with a portion defined by a radius. The lever surface may include a cam surface. The handle is movable from a first position to a second position; when in the first position, at least a portion of the handle body and the first end are positioned between the top surface and the lower edge, and, when in the second position, the top surface and the lower edge positioned between the handle body and the handle first end. The handle can include a second end opposite to the first end, the second end having a lever surface. 
   According to the present invention, methods of removing and replacing a bag filter are provided. A method for removing a filter tube frame from a tube sheet, the filter tube frame being held within the tube sheet with a compressive force, includes: grasping a handle body, pivoting the handle body away from the tube sheet and pivoting a distal end of the handle toward the tube sheet, contacting the tube sheet with the distal end, releasing the compressive force holding the filter tube frame, and extracting the filter tube frame from the tube sheet. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of a bag house dust collector, with portions being shown broken away to show internal detail; 
       FIG. 2  is a side view of a filter tube frame according to the present invention used in the bag house of  FIG. 1 ; 
       FIG. 3  is a side view of an end cap of the filter tube frame of  FIG. 2 ; 
       FIG. 4  is a top view of the end cap of  FIG. 3 ; 
       FIG. 5  is a side view of the end cap of  FIG. 2  positioned as if the filter tube frame were inserted in a tube sheet, illustrating a handle thereof in a first position; and 
       FIG. 6  is a side view of the end cap of  FIG. 5  with the handle in a second position, illustrating the end cap partially raised from the tube sheet. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The reference numeral  10 ,  FIG. 1 , generally designates a dust collector or bag house incorporating a filter tube frame according to the present invention. Except as described herein with respect to the connector assembly or arrangement, the dust collector  10  may be a conventional dust collector. The details shown in the drawing depicted are of a Donaldson Model RFW RF dust collector, appearing in a Donaldson Company, Inc. 1994 publication. A reason that the drawing of  FIG. 1  is not labeled as prior art, is because according to the present description, it includes a filter tube frame according to the present invention therein. It is noted, however, that in  FIG. 1  details of the filter tube frame are not viewable. 
   Still referring to  FIG. 1 , dust collector  10 , which is depicted with portions broken away, includes an outer housing  12  having a dirty air inlet  14  and a clean air outlet  15 . Tube sheet  17  separates housing  12  into a dirty air side or section  18  and a clean air side, section or plenum  19 . Extending into dirty air section  18  are a plurality of spaced filter tubes or bags  20 . Each filter tube or bag  20  has a clean air exit port or open end  22  associated with or adjacent to tube sheet  17 . During operation, clean air exits from open end  22  into clean air section  19 . 
   In operation, dirty air passes into housing  12  through dirty air inlet  14 . The air is then directed through filter tubes or bags  20 . As the air enters bags  20 , particulate material carried in the air is trapped on outer walls  24  of bags  20 . Clean air passes through the filtering walls of bags  20  to the inside of bags  20 , then passes upwardly and exits through open ends  22  (of bags  20 ), as sealingly carried by tube sheet  17  and into clean air section  19 . The clean air is then exhausted or vented through clean air outlet  15 . 
   For the arrangement shown, dust collector  10  includes an inlet baffle construction  26 , a filter tube access door  27 , a dust collector hopper  28 , and a dust outlet  29 , in a manner known in the art. 
   In addition, the arrangement shown includes a compressed air apparatus generally designated at  30 , for periodic cleaning of filter tubes or bags  20 . In general, this compressed air apparatus  30  provides for selected periodic pulses of pressurized gas in a direction of backflow through filter tubes or bags  20 . This will push collected dust off of the bag outer walls  24 , causing the dust to fall into hopper  28 , from which it can be removed via dust outlet  29 . A pressurized air reservoir for use in conducting this cleaning operation is depicted at  31 . Compressed air cleaning arrangements of the type depicted and described are also conventional for dust collectors. 
   In a large industrial dust collector of the type shown in  FIG. 1 , tube sheet  17  will typically include from 48 to 484 holes therein, for attachment of individual filter bags  20 . The arrangement, then, will typically include 48 to 484 filter bags  20 . 
   At initial startup, it is necessary to install filter bags  20 . This is generally done by a worker who enters through access door  27  and stands on or over tube sheet  17  and installs bags  20  through tube sheet  17 . Periodically thereafter, filter bags  20  need to be serviced or replaced, which requires filter bags  20  to be removed from tube sheet  17 , generally in opposite manner in which they were installed. Filter bags  20  are supported by a filter tube frame, which inhibits the bag from collapsing and which also provides a grip for removing filter bag  20  from tube sheet  17 . In order to remove bag  20 , it is also necessary to remove the filter tube frame from tube sheet  17 . It is presently estimated that through the lifetime of an apparatus such as dust collector  10 , each of filter bags  20  will be removed and replaced at least 20 to 40 times. 
   The present disclosure illustrates a preferred filter tube frame, which facilitates the removal of filter tubes  20  from tube sheet  17  in a relatively convenient and relatively efficient manner. A filter tube frame according to the present invention is depicted in  FIGS. 2-6 , where like reference numerals designate like elements. 
   Referring to  FIG. 2 , a filter tube frame  100  is depicted. Filter tube frame  100  has a first end  102 , an opposite second end  104 , and a cage  105  extending therebetween. Cage  105  is generally a cylindrical cage made from a plurality of metal rods; it is understood that other configurations can be used for cage  105 , such as an oval, ellipse, or other shape. Cage  105  is typically at least about 25 inches long and usually no greater than about 180 inches (15 feet), however in some designs, longer cages  105  may be used. Cage  105  may be open or closed at second end  104 . An end cap  110  is secured to first end  102  of cage  105 . The framework represented by cage  105  can be connected to end cap  110 , for example by welding. Additionally, in this embodiment, positioned within cage  105  at first end  102  is a Venturi  106 , for altering the flow of air at first end  102 . Venturi  106  includes a top plate  106 ′; a first portion of Venturi  106  opposite top plate  106 ′ extends into cage  105 . A second portion of Venturi  106  extends through end cap  110 , and will be further described below. 
   Attention is now directed to  FIGS. 3 and 4 , which depict various views of tube frame end cap  110 . End cap  110  has a flange  113  which is generally defined by an outer periphery  112 , best seen in  FIG. 4  where a top plan view of end cap  110  is depicted; in this embodiment, flange  113  and outer periphery  112  are circular to correspond to cylindrical cage  105 . Flange  113  also has an inner rim  114  which defines an internal aperture. The second portion of Venturi  106 , mentioned above, extends through inner rim  114  of flange  113  so that top plate  106 ′ of Venturi  106  is positioned on flange  113 ; top plate  106 ′ forms a top surface of end cap  110 . Venturi  106  is typically attached to flange  113  by bolts or rivets through top plate  106 ′. 
   As seen in  FIG. 3 , flange  113  of end cap  110  at outer periphery  112  includes a lower edge  116 , the use of which as a seat will be described below. Between inner rim  114  and periphery  112  (and edge  116 ), a recess or cavity  115  is provided. Recess  115  extends from lower edge  116  and is adapted for accepting a top portion of filter bag  20  therein when bag  20  and filter tube frame  100  are mounted into tube sheet  17 ; this will also be further described below. Extending from flange  113  is a collar  118 , whose function is to provide compressive fit and support to bag  20  when mounted on filter tube frame  100 . Collar  118  is sized to fit between Venturi  106  and cage  105 . End cap  110  has a handle  120  pivotally attached to periphery  112 . 
   Handle  120  has an elongate body  122  defined by distal ends  127 , specifically, first distal end  127   a  and opposite second distal end  127   b . Positioned between distal end  127  and body  122  is a pivot point  125 ′, at which attachment member  125  connects handle  120  to end cap  110 . Distal end  127  extends past attachment member  125 . Handle  120  is pivotable around two pivot points  125 ′ positioned opposite or across from each other on outer periphery  112  (e.g., 180 degrees) of end cap  110 . Pivot point  125 ′ is located at attachment member  125 , and handle  120  extends between one pivot point  125 ′ and attachment member  125  and the opposite pivot point  125 ′ and attachment member  125 . 
   Pivot point  125 ′ is located a distance “x” from lower edge  116  of periphery  112 . Preferably, pivot point  125 ′ is positioned at the center of the width of handle  120 . 
   Handle  120  is usually metal, for sufficient strength, and may be generally flat, circular, or have any other suitable cross-sectional shape. The shape of handle  120  may vary along its length from first distal end  127   a  to second distal end  127   b . Body  122  may include features to improve gripping of handle  120 , features such as knurling or other texture. 
   Handle  120  is generally semi-circular in shape and, when generally parallel to outer periphery  112  as illustrated in  FIG. 3 , handle  120  extends out and away from outer periphery  112  of flange  113 . The amount of extension of handle  120  from outer periphery  112  should be sufficient to allow a maintenance worker or other user to be able to get at least part of their fingers between handle  120  and periphery  112 . Often, a space of at least 0.25 inch is sufficient, although a space of at least 0.5 inch is more comfortable. The distance between handle  120  and outer periphery  112  is at least 0.25 inch; this distance is no more than about 2 inches. Typically, the distance is 0.5 to 1.5 inches, and preferably, the distance is about 0.5 to 0.75 inch. 
   The length of handle  120  depends on the size of flange  113  and end cap  110  and is usually at least one-half of the distance or length of outer periphery  112 , or, of the perimeter of flange  113 . This provides the extension of handle  120  between the two pivot points  125 ′. The length also includes some extra to accommodate the extension of handle  120  from outer periphery  112  (as described above) and includes some extra to accommodate for distal ends  127  of handle  120 . 
   At least one of distal ends  127 , that is, at least one of end  127   a  and end  127   b , extends past pivot point  125 ′ a distance of at least “x”, the distance from pivot point  125 ′ to lower edge  116 . Preferably, both distal ends  127   a ,  127   b  extend past pivot point  125  a distance of at least “x”. Distal end  127  extends at least 0.25 inch past pivot point  125 ′ and no more than about 4 inches. Preferably, this distance is about 0.5 to 1.5 inch, more preferably about 0.75 to 1 inch. 
   Distal end  127  that extends past pivot point  125 ′ has a shape that provides a lever surface  129 . In the embodiment illustrated in  FIG. 3 , lever surface  129  includes a radius region that has a smooth curved edge positioned between attachment member  125  and distal end  127 . Advantages of lever surface  129  will be described below. In preferred designs, both ends  127   a ,  127   b  have lever surface  129 . In some embodiments, lever surface  129  may include a cammed portion or cam surface. 
   In operation, the filter tube or bag  20 , which is of a flexible fabric construction, is snapped into an aperture in tube sheet  17 . The top end of bag  20  usually includes a soft, polymeric o-ring, which is sized to fit into recess  115  of end cap  110 . Once bag  20  is engaged in tube sheet  17 , filter tube frame  100  is slid into bag  20  until end cap  110  contacts tube sheet  17 , particularly, lower edge  116 , and any o-ring at the top of bag  20  seats within recess  115 . Thus, frame  100  is positioned inside bag  20  during use, and provides internal support for bag  20 . See  FIG. 5 , although no bag  20  is illustrated. Filter tube frame  100  is typically secured into tube sheet  17  by a radial compressive friction fit. Stepping on flange  113  is a typically way for the operator to assure that frame  100  and bag  20  are locked into position. 
   During filtration, handle  120  is positioned in a flat or downward position, such as illustrated in  FIG. 5 . Preferably, no portion of handle  120  is positioned within the aperture defined by inner rim  114 ; any protrusion of handle  120  into that aperture could detrimentally alter the air flow patterns and reduce filtering efficiency. As seen in  FIG. 5 , distal end  127  is positioned above the level of lower edge  116 . 
   When it is desired to remove the bag and filter tube frame  100  from tube sheet  17 , for example, to remove and replace bag  20 , handle  120  is grasped by the operator or maintenance person and pivoted around pivot point  125 ′. See  FIG. 6 . Typically, handle  120  is lifted about 0.5 inch to allow an operator&#39;s fingers to grasp under handle  120 . As handle  120  is pivoted upward, distal end  127  drops below lower edge  116  (that is, distal end  127  gets closer to second end  104  of filter tube frame  100 ) until lever surface  129  of distal end  127  contacts tube sheet  17 . Distal end  127 , specifically lever surface  129 , urges end cap  110  and bag  20  away from tube sheet  17  as handle  120  is raised, as indicated in  FIG. 6 . Because a portion of handle  120  larger than distal end  127  is being lifted by the operator, a mechanical advantage is achieved. Distal end  127  with lever surface  129  facilitates the removal or extraction of filter tube frame  100  from tube sheet  17 . 
   To replace filter tube frame  100  into tube sheet  17 , generally the reverse action is used. Handle  120  can be used to lower tube frame  100  into tube sheet  17 . Once properly aligned, handle  120  should be pivoted and positioned generally parallel to tube sheet  17  (as illustrated in  FIG. 5 ) and end cap  110  fitted into place. 
   A Particular Preferred Filter Tube Frame 
   A particular preferred filter tube frame  100  as depicted in  FIG. 2 , having an end cap  110  as depicted in  FIGS. 3 through 6 , would be as follows. 
   Cage  105 , from first end  102  to second end  104 , is usually about 48 inches to 144 inches long with a diameter of about 4 to 18 inches. One preferred length is 120 inches and one preferred diameter for cage  105  is about 6 inches. Cage  105  is made from metal, such as mild steel, galvanized steel, or #304 stainless steel. 
   End cap  110 , present at first end  102 , includes flange  113  defining outer periphery  112  and inner rim  114 ; in one preferred embodiment, flange  113  has an outer diameter, defined by outer periphery  112 , of about 7 inches, and an inner diameter, defined by rim  114 , of about 5.7-6 inches. Flange  113  is often made from metal and is welded to cage  105 . Inner rim  114  is preferably aligned with cage  105 . Outer periphery  112  includes lower edge  116 . Recess  115  is generally the depth of exposed outer periphery  112 , or close thereto. In one preferred embodiment, recess  115  has a depth of about 0.6 inch. 
   Attached at periphery  112  is handle  120 ; preferably, handle  120  is attached at two pivot points  125 ′ via rivets  125  directly opposite one another on flange  113 ; that is, pivot points  125 ′ are preferably separated by 180 degrees. 
   Handle  120 , from first distal end  127   a  to second distal end  127   b  is usually about 12 to 18 inches long; one preferred length for handle  120  is about 13.7 inches for use with a flange having a diameter defined by outer periphery  112  of about 7 inches. The length of handle  120  is such that handle  120  extends out from outer periphery  112  of flange  113  when handle  120  is operationally mounted to flange  113 . The space between handle  120  and flange  113  should be sufficient to allow a maintenance worker or other user to be able to get at least part of their fingers between handle  120  and flange  113 . Usually, the distance the handle extends from periphery  112  is 0.5 to 1 inch; in one particularly preferred embodiment, this distance is about 0.545 inch. 
   As stated above, handle  120  may be flat, round, obround, or any other suitable shape. Handle  120  is preferably no thicker than the distance between top  106 ′ and lower edge  116 . When handle  120  is flat, it is usually about 0.25 inch to 1 inch; one preferred width is 0.375 inch. Handle  120  can be made from 0.125 inch thick steel. 
   The length from pivot point  125 ′ to distal end is at least “x”, typically at least the thickness of flange  113 , and no more than about 4 inches. Often, this distance is 0.5 inch to 1.5 inches, more often, about 0.5 inch to 1 inch, or 0.75 inch to 1 inch. One preferred length is about 0.8 inch, particularly, 0.813 inch. Distal end  127  includes lever surface  129 ; one preferred lever surface  129  has about a lever surface  129  defined by a radius of about 0.2 inch. 
   It is to be understood that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the disclosure, such disclosure is illustrative only, and is not intended to be limiting to the scope of the invention in any manner, other than by the appended claims. The specific dimensions referenced in this description provide one preferred embodiment of a filter tube frame and an end cap. The invention is not to be limited to the described embodiments, or to the use of specific components, configurations or materials described herein. Equally preferred designs and embodiments can be obtained with appropriate variation. All alternative modifications and variations of the present invention which fall within the broad scope of the appended claims are covered.