Note: Descriptions are shown in the official language in which they were submitted.
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BACK~RO~IND O~ TH~ INVENTION
1. Field of khe Invention
The present invention relates to a bag filter that
provides for economy of manufacture by defining an arrange-
ment by which independent bags thereof may be cleaned, re-
moved, or repaired quickly during operating while permitting
only a limited amount of leakage of relatively high pressure
atmospheric air into the low pressure housing that would sig-
nificantly increase the volume of air to be filtered and,
0 consequently, lower the efficiency of the filter.
2. Description of Prior Art
~o avoid complete shut-down during periods of
cleaning or repair, therefore, bag fllters are customarily
constructed of independent modules having both inlets and
outlets, side walls and end walls so they comprise a multi-
plicity of completely self-sufficient units in the manner
shown by U. S. Patent #3,078,646 R. R. Leech, and U. S. Patent
#3,092,479 of C. W. Hedberg. In bag filters comprised of
two or more modules, all modules are completely independent
0 from one another so that any module may be taken "off the
line" for replacement, cleaning, or repair while all other
modules continue to remain in full operation. In a ten
module bag filter, for example, the bag filter would operate
at 90% capacity while any one unit was deactivated to permit
cleaning or repair of the bags therein. While such units
are in many ways effective, they are cumbersome and expensive
to manufacture because they require a great duplication of
structure; i.e., side walls, inlets, outlets, and valving
devices in order that each module be operatively self-suffi-
0 cient
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Thus, avai.l~ble devices may function effectively,
but in order that they remain continuously operative, they
entall the use of duplicate structure which results in ex-
cess weight and excessive manufacturing costs that may pro-
hibit their general use.
SUMMARY OF THE INVENTION
The arrangement defined by this invention, there-
fore, provides a lightweight, essenkially unitary, bag filter
which may be constructed economically by eliminating dupli-
U cate structural side walls, ducting, and various valving
features while maintaining modular structure at the outlet
to provide the operational advantages of a modular device.
Moreover, the device defined by this invention provides for
an arrangement of a bag filter whereby it may be serviced
completely from a vantage point outside the housing of the
bag filter, and it provides for rapidity of repair because
a multiplicity of filter bags may be simultaneously removed.
This invention provides generally for a bag filt;er-
house having a series of porous filter bags hanging in an
0 undivided inlet chamber that is being supplied dust entrained
fluid by a single inlet. After traversing the porous filter
bags and depositing dust thereon, the clean gas passes to an
outlet chamber that is divided into a multiplicity of inde-
pendent sub-compartments3 each of which has an independent
outlet that is individually controlled.
After fluid flow through an individual compartment
has been stopped by closure of a valve in the outlet therefrom,
the dampers at the end of each filter bag are moved to a
closed position to prevent the influx of relatively high
0 pressure at~nosphere into the low pressure area within the
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housing, and a filter bag may then be removed for replace-
ment or repair. Some atmospheric air will immediately flow
through the opening in the tube sheet, back into the housing
to increase the volume of fluid to be filtered, but such
flow is limited, and it is calculated to provide only a mini-
mal loss of efficiency that is considered entirely acceptable
in view of the inherent economic advantages.
BRIEF DESCRIPTION OF THE DR~WING
Other objectives and means of operation ~ill be-
come more apparent from the specification and accompanying
drawings in which:
Figure 1 is a perspective view of a bag filter~
partially cut away, showing the details of this device,
Figure 2 is a transverse sectional view of a modi-
fied form of device, and
Figure 3 shows a perspective view of a further modi-
fied form of valving arrangement.
DESCRIPTION OF THE PREFERRED EMBODIMENT
. . _ . . _ . . _
Referring particularly to Figure 1 of the drawing,
the apparatus comprises a housing 10 having an inlet 12 for
a dust bearing gas and a plurality of spaced outlets 14 for
the exhaust of clean gas therefrom. The housing encloses a
chamber that is divided into inlet and outlet portions 16-18
by a tube sheet 22 having a series of apertures 24 therein.
The apertures are covered by a venturi-shaped jet deflector
26 that extends above tube sheet 22 into the clean air
chamber in accordance with standard practice, and they in-
clude a porous bag filter 28 that depends therefrom and extends
into the inlet chamber on the opposite side of the tube sheet.
A skeletal metallic cage 29 inside each bag filter may be
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provided in accordance with standard procedure to depend f'rom
the jet deflector and provide a support whereby each bag may
be held continuously in its cylindrical form. Each jet de-
~ flector is removably attached to the tube sheet whereby the
jet deflector 26, together with the attached cage that supports
the bag filter 28, may be lifted from the sheet 22 and re-
moved from its surrounding aperture.
In the space above each bag filter a nozzle 36 is
attached to an elongate supply tube 38 leading to an air
.0 supply manifold 42 at the side of the housing that receives
a ~uantity of air from a source not here illustrated. A simi-
lar tube and nozzle arrangement is provided above each series
of bag filters whereby compressed air may be directed there-
through and into the open end of each jet deflector. A valving
.5 device 44 remains normally closed but is actuated by a con-
ventional timing device (not shown) to open according to a
predetermined schedule to permit a blast of air to flow into
the open end of the jet deflector and remove a collection of
dust from the outer surface thereof.
'0 The single inlet chamber 16 has an inlet 15 thereto
while the outlet chamber of the housing is divided by a series
of slde walls 46 into sub-chambers L18, each of which has its
own outlet 14 depending therefrom, said outlet ducts 14 being
closable by a manual valve 20. Thus, the inlet chamber com-
'5 prises a housing enclosing a single chamber while the outlet
chamber includes a plurality of similar sub-assemblies that
comprise a plurality of outlet chambers, each with a valved
outlet duct that leads to a source of negative pressures, such
, .
as an induced draft fan (not shown).
~0 In accordance with this invention there is also
pro~ided a damper drive rod 50 that may be actuated to cover
the ends O:r the bag ~ilters with damper valves 58. This damper
drive rod is pivoted at 54 în opposite walls of the filter
housing and terminates in a manually operable actuator 56
~5 adjacent the outside of the housing wall. From each damper
drive rod depends the dampers 58 that are adapted to cover
the open ends of the bag filters whereby there can be no fluid
flow therethrough when a damper is moved over the end of a
bag filter. Each damper unit includes a rocker release set
O screw 62 whereby manual manipulation thereof permits the
damper to be loosened from the drive rod 50 and then pivoted
aside so that a subjacent filter bag may be readily removed
while the remaining filter bags in a given compartment re-
main closed to flow therethrough.
When pivotally moved off its seat at the end of an
individual bag filter, some ambient air will immediately
commence to flow through the opening back into the low pres-
sure area within the housing. However, cleaning or repair
may be effected quickly since no encumberances will slow the
O removal of the filter and only a minimum amount of atmospheric
air will be lost. If it is necessary that a filter be re-
moved for a period of time that would permit an extended
period of air flow into thé filter housing, an imperforate
plate or plug may be placed over the opening 24 to substan-
tially terminate such flow so that its cleaning efficiency will
not be lowered.
Upon turning of the actuator 56 to a horizontal
position, each damper is designed to pivot with the damper
drive rod to cover the entire outer surface of nozzle 36 and
preclude fluid flow therethrough in the manner shown by Fig. 1.
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~therwise~ the damper could be adapted to swing about the
damper rod and actually enter the opening in the open ended
deflector, as shown in Figure 2, to produce a valving action
thereby. In the arrangement shown by Figure 2 a single damper
~5 may be pivoted aside to permit the removal of a single filter
bag, thus, allowing less leakage than if a plurality of bags
were simultaneously removed.
From a practical standpoint, however, it has been
determined that less downtime is required for replacement or
0 repair if a plurality of filter bags in the assembly were
arranged in lateral sub-assemblies with an "on-off" plate-type
valve for each row in the manner shown by Figure 3.
~ere, an entire transverse row of filter bags is
seated upon a lateral tube sheet 62 that is removably secured
at 64 to the major tube sheet 22. An elongate sheet of steel,
or other suitable material, is formed to provide valve means
66, that when attached to the damper drive rod 50, seats upon
; the open ends of all nozzles 36 in a given lateral row. Thus,
upon actlvation of handle 56 to a vertical position, rod 50
O moves the valve means 66 off of all bag nozzles 36 whereby the
lateral tube sheet 62, with its depending filter bags, may be
removed as a sub-assembly. A clean or new sub-assembly may
be substituted therefore, and quickly installed by tightening
the screws 64 at the sides thereof to again provide an integral
assembly.
A cover plate 72 is adapted to be removably attached
by bolts 74 to flange 76 whereby each outlet compartment may
be readily opened for ready access to the equipment therein.
In operation, when it has been determined to remove
O or replace one or more filter bags in a given compartment, all
the manual actuators 56 ~or that compartmen~ are movcd to a
horizontal position to move the dampers over the ends of the
bag filters to terminate the flow of air therethrough.
Valve 20 in the outlet duct 14 is then turned to
a "closed" position to terminate the flow of induced air
therethrough. Thus, the flow of all process air from inlet
12 is effectively terminated in the "closed" chamber to pro-
duce a "bottled-up" effect while it continues at full flow
through the remaining chambers of the filter housing.
Cover plate 72 is then removed to make accessible
the contents of the entire outlet compartment.
Valve 44 in the duct for cleaning air is then closed
so ducts for compressed cleaning air that lie adjacent the
open ended nozzles 36 of the bags to be removed may be freely
~;5 disconnected and removed from the outlet chamber whereby they
cannot impede access to the ends of the bags.
At this point, if arranged in the manner illustrated
by Figure 2, a single damper valve 25 is pivoted aside by
first loosening thumbscrews 62 on actuating rod 50. An entire
0 fil~er bag may then be removed and quickly replaced by a ~lew
bag or one that has been properly cleaned and repaired. Rod
27, with damper 25, is then returned to a closed position,
thumbscrew 62 tightened, air duct 38 and cover 72 replaced,
and valves 19 and 44 opened so that full operation may be
~5 immediately resumed.
By an arrangement shown in Figure 3 it is possible
to simultaneously remove a plurality of filter bags that lie
under an elongate damper 66. Here~ after the damper 66 is
moved aside, the apertured plate 62 is loosened by removal
0 of connections 64 and the entire sub assembly of plate 62 and
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all the filter bags extending therethrough may be removed
and properly replaced.
While this invention has been described with refer-
ence to the illustrated species it is apparent that the present
invention may be embodied in other specific forms without, de-
parting from the spirit of the invention.
