Reverse gas-flow bag filter

A bag filter having a self-sealing cuff at the upper open end thereof, a bottom support at the closed end to tension the bag and prevent flapping and a plurality of spaced anticollapse rings each of which encircles an annular outer surface of the bag to which it is attached between the ends of the bag to prevent bag collapse.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to gas filters and more particularly relates to 
reverse gas-flow bag filters for removing solids entrained in a gas, of 
the type adapted to be mounted in the aperture of a dividing plate so that 
a gas on one side of the dividing plate is caused to flow into the bag and 
out at the other side of the dividing plate. 
2. Brief Description of the Prior Art 
Reverse gas-flow bag filters are described in British Pat. No. 887,772 
(published Jan. 24, 1962) together with a complete disclosure of their 
installation and use in a bag filter housing. In general, this type of bag 
filter has the structure illustrated in the accompanying drawing of FIG. 
1. As shown in FIG. 1, the reverse gas-flow filter comprises a tube 3 
fabricated from a filter fabric and having a closed end 4 and an open end 
5. The tube 3 is supported by a tubular frame 6 comprising vertical struts 
7 tied together and inserted into tube 3 through the open end 5. The tube 
3 with its supporting frame 6, is mounted in an aperture of a dividing 
plate 8 which is a component of a conventional bag filter housing, 
sometimes commonly referred to as a "bag house". The space between the 
tube 3 and dividing plate 8 is filled with a gasket material 9 to form an 
air-tight seal between tube 3 and dividing plate 8. The mounting of tube 3 
and the support frame 6 is generally effected by threading the collar of 
frame 6 and securing it with a large nut (not shown) to the dividing plate 
8. In operation, a gas contaminated with solids is directed into the bag 
house, housing generally a plurality of filter bags mounted on the 
dividing plate. The contaminated gas passes through the filter, whereupon 
the solids are left on the outside surface of the bag filter. The filtered 
gas passes from the filter through the open end 5 for release on the 
outside of the dividing plate 8. After a period of time, solids build up 
on the outside of tube 3 and reduce the flow of gas therethrough. To 
correct this, periodically the flow of gas is reversed to flex the tube 
walls and cause the built up solids (commonly referred to as a "dust 
cake") to fall off the filter. 
The prior art reverse gas-flow filter bags known heretofore have not been 
entirely satisfactory for a number of reasons. For example, the 
requirement for a support frame to support the tubular wall of the fabric 
bag is costly in terms of the added cost in their initial provision and in 
terms of their increasing the wear and tear on the fabric bag. More 
specifically, continued and periodic flexing of the tube or bag wall 
during reverse gas-flow cycles abrades the fabric where it contacts the 
supporting frame. This abrasion problem is of such magnitude that 
heretofore it has been impractical to use the highly abrasion prone glass 
fabrics for fabrication of reverse gas-flow bag filters. Of course the use 
of glass fabric bags would be highly desirable and advantageous where the 
gas to be filtered is maintained at a high temperature, restricting the 
use of other filter fabrics. 
The prior art filter bags have also required relatively costly and complex 
hardware arrangements for securing to the dividing plate of the bag house. 
A gas-tight seal with the plate is required. This generally requires 
separate sealing components and fasteners. In addition, those skilled in 
the art readily appreciate the manpower requirements for installing, 
removing and replacing the prior art bag filters with their associated 
mounting hardware. 
The improved reverse gas-flow filter bags of my invention are simple to 
construct, unitary, do not require a separate support frame upon which the 
inner surface of the bag can abrade, are quickly installed or removed 
without special tools and are self-sealing with the dividing plate of the 
bag housing. 
British Pat. No. 1,206,544 discloses a reverse gas-flow bag filter 
supported by external "stiffening rings". 
SUMMARY OF THE INVENTION 
The invention comprises, a reverse gas-flow type of bag filter for removing 
solids entrained in a gas, which comprises; 
a tube having an open end, a closed end and wall joining said ends, said 
tube being fabricated from a gas-permeable filter fabric for filtering 
solids from a gas; 
a wall support member disposed between said open and closed ends, attached 
to a portion of the wall of said tube; 
means for connecting said closed end to a means for tensioning said tube 
along its lengthwise axis, said connecting means being associated with 
said closed end; and 
a collar associated with said open end for sealingly mounting said tube in 
the filter bag aperture of a dividing plate of a bag filter housing, said 
collar comprising, 
(a) a cuff formed by folding the wall of said tube adjacent said open end, 
in the direction of said closed end; and 
(b) a gas sealing member within said cuff, said sealing member including a 
first sealing surface for engaging the inner surface of said dividing 
plate and a second sealing surface for engaging the outer surface of said 
dividing plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
For convenience in appreciating the invention, the following description of 
the invention should be read in conjunction with the accompanying drawings 
of FIGS. 1-8, inclusive. Referring first to FIG. 2, an isometric view of 
an embodiment bag filter 10 of the invention is seen mounted in the 
dividing plate 12 of a bag filter housing. The bag 10 is tensioned along 
its lengthwise axis by attachment to the floor of the baghouse (not shown 
in the drawing) through cable 14. Cable 14 is secured to bag 10 through 
eyelet 16 piercing the tab 18 formed by stitching the end 20 of bag 10 
closed. The bag 10 is fabricated from any conventionally employed filter 
fabric conventionally used to filter solids entrained in a gas. Thus, for 
example, wall 22 of bag 10 may comprise textile fabrics such as nylon, 
acrylic, acrylic-vinyl copolymers, polyethylene, polypropylene, 
polytetrafluoroethylene, glass fiber and the like. The filter bags of the 
invention are particularly advantageous for fabrication from glass fiber 
fabrics. 
The bag 10 has a tubular body closed at end 20 and open at end 24. The bag 
10 more particularly has a tubular body round in cross-section and 
supported from collapse by a plurality of rings or support members 26 
attached to wall 22 and encircling the outer periphery thereof. The 
members 26 are disposed between ends 20,24. The bag 10 is mounted in the 
filter bag aperture of the dividing plate 12 and embraces plate 12 as 
shown in FIG. 4 in such a manner that the joinder between bag 10 and plate 
12 is gas-impermeable. 
Referring now to FIG. 3, a cross-sectional view-in-part of an embodiment 
collar 28, further details of this component may be observed. For clarity, 
the components of collar 28 are shown slightly separated and not in their 
true positions. The wall 22 at the open end 24 of bag 10 is folded, 
preferably outwardly, towards the closed end 20 to form a cuff 30. The top 
of cuff 30 is folded again to form tab 32 for strength, the cuff 30 being 
stitched to wall 22 as shown by the transverse, broken lines. Enclosed by 
cuff 30 is a sealing member 34 which comprises a support 36 which may be 
any hard surfaced, planar structure such as a metallic band. Positioned on 
the outer surface of support 36 is gasket 38 which may be any gas sealing 
material such as a synthetic or natural polymeric resin elastomer; for 
example rubber, non-cellular polyurethane elastomer, and the like. The 
upper end of gasket 38 has associated therewith a bead 40 and the lower 
end of gasket 38 has associated therewith a bead 42. Beads 40,42 may be 
fabricated from the same or different materials as gasket 38. In a 
preferred embodiment, beads 40,42 are integrally molded parts of gasket 
38. As shown in FIG. 3, support 36, gasket 38 and beads 40,42 are disposed 
within fabric pouch 44. Pouch 44 protects the enclosed components and 
supplies bulk to the collar 28. Pouch 44 is advantageously fabricated from 
the same fabric used for wall 22. 
Referring now to FIG. 4, a cross-sectional view along lines 4--4 of FIG. 2, 
it is noted that the cuff material is sandwiched between the gasket and 
plate 12 thereby avoiding the passage of gas between bag and plate 12. As 
set forth above, the collar 28 comprises a cuff 30 formed by folding a 
portion of wall 22 at end 24 toward the closed end 20 and stitching the 
cuff to wall 22. For added strength the end or tab 32 at the top of the 
cuff is folded under the stitch line. Supporting the gasket 38 is 
preferred and a metallic band 36 is positioned within pouch 44 to support 
gasket 38 against plate 12. Any other supportive material such as a 
non-cellular plastic or the like may also be used. The band 36 may be 
bonded to gasket 38 if desired to assure maintenance of its position. The 
pouch 44 supplies bulk to the collar 28 to assure a good seal with plate 
12 and also aids in maintaining positional integrity of sealing member 34 
and its component parts. 
Those skilled in the art will appreciate the convenience offered by bag 10 
in respect to its ease of installation or removal from mounting in the 
aperture of a dividing plate 12. By proper selection of size, bag 10 will 
have a diameter between beads 40 and 42 slightly larger than the diameter 
of the aperture. Since the beads 40 and 42 are elastic, bag 10 is readily 
pressed into place as shown in FIG. 4, to take advantage of the 
self-sealing attributes of the bag 10. Nuts, threaded collars, etc. are 
not required to secure bag 10 in place on plate 12, the frictional fit of 
the collar 28 and the flange effects of beads 40,42 being sufficient to 
secure the attachment of bag 10. 
Those skilled in the art will appreciate that many modifications may be 
made to the embodiment bag 10 of the invention without departing from the 
spirit of the invention. For example, tab 18 and eyelet 16 are just one 
means of attaching the closed end 20 to a means for tensioning bag 10 
along the lengthwise axis. As shown in FIGS. 5-8, alternate means of 
connecting closed end 20 comprise the employment of a tie-down strap 46 
(FIG. 5), a loop 48 (see FIG. 6) that may be secured to an "L" shaped rod, 
a hanger 50 (see FIG. 7) which may connect with a "J" hook or a hook 52 
(FIG. 8) which facilitates connecting with a "J" hook or an eyelet. 
Those skilled in the art will also appreciate that in the bag of the 
invention, the collar 28 is unitary and does not require attachment to a 
stiff collar or thimble of dissimilar material. This provides a long 
wearing collar.