Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to filter apparatus utilizing a movable
continuous filter ~edia for filtering relatively large volumes of liquid
used for or in conjunction with various industrial processes.
ackground of the Invention
I have previously proposed a filter apparatus wherein an inclined
movable belt or conveyor is utilized to support a continuous strip of filter
media. For certain filtering applications it may be desirable to provide an
apparatus that utilizes a movable continuous strip of filter media which
does not require a belt or conveyor to support the media. In such an
apparatus the media from a suitable supply roll is supported on a fixed
structure and pulled by a suitable means capable of gripping the front or
free end of the media. The filter media forms the bottom of a receiving
tank for dirty liquid to be filtered and directly below it is a collection
tank for clean liquid. A suction pump attached to an outlet from the
collection tank creates a reduced pressure in the collection tank which
increases the flow of liquid from the receiving tank through the media. When
the suction pump is in operation, the reduced pressure created thereby in
the collection tank causes the filter media to cling tightly to its support-
ing grill and in this position the media continues to trap more and more
filtrate on its upper surface. As filtered out material from the dirty
liquid continues to build up on the filter media the pressure in the collec-
tion tank becomes progressively less, as well as the flow of liquid through
the media. It thus becomes necessary to advance the media to provide fresh,
unloaded filter media. However, in an apparatus with no belt or conveyor,
movement of the loaded media becomes difficult, if not impossible, if the
pressure differential between the receiving and collection tanks is relative-
ly high, that is, if the pressure in the collection tank remains substantially
lower from that in the receiving tank. Thus, it became essential to provide
a solution to this problem of equalizing the pressure in the receiving and
collection tanks just prior to movement of the filter media.
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Brief Summary of the Invention
The invention provides a filter apparatus comprising:
wall means including spaced apart side wa].ls forming a receiving
tank for dirty liquid to be filtered, a collectiol tank below said receiving
tank for clean filtered liquid and an auxiliary reservoir for clean liquid
adjacent said receiving tank;
a fixed inclined pervious means for supporting a layer of movable
filter media forming the bottom of said receiving tank;
means for supplying an elongated sheet of filter media to the
upper side of said pervious means;
means for seallng the periphery of said collection tank to prevent
dirty liquid from migrating from said receiving tank around the side edge of
the filter media into said collection tank;
means at the forward end of said apparatus for pulling the filter
media over said pervious means;
a suction pump attached to an outlet from said collection tank for
reducing pressure therein duri.ng the operation of said apparatus to increase
the flow of liquid through said filter media;
means responsive to a predetermined low pressure level within said
collection tank due to accumulation of filtered out material on said filter
media for temporarily substantially equalizing the pressure in said collection
and receiving tanks and thereafter for automatically controlling said media
pulling means to move said media up said inclined pervious support means.
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In the disclosed embodiments the side and rear edges of the
collection tank are sealed by the filter media and by clean liquid constantly
supplied from a reservoir at a pressure greater than that of the dirty liquid
in the receiving tank. The pulling device for advancing the filter media is
activated by a control system that includes a pressure operated outlet valve
connected to the outlet of the suction pump. The outlet of this valve is
connected to the main conduit to the process using the clean filtered liquid,
but it is also connected to a branch line to an eductor which is connected
to conduits extending to the supply reservoir for the clean sealing liquid
and also to a pair of vacuum switches in the collection tank. When the
filter media commences to get clogged and the pressure in the collection tank
falls below a predetermined level~ the outlet valve is closed by a first
vacuum switch. This reduces the liquid pressure normally supplied to the
eductor and consequently the flow in the eductor is reversed. This breaks
the near vacuum in the collection tank which actuates the second vacuum
switch, thereby closing a circuit to the drive motor and activating the media
puller. With the vacuum in the collection tank broken, the forces on the
media are more equal and friction is reduced so that the media can be readily
moved. The puller is deactivated on a preset time delay after a predeter-
mined amount of fresh media has been moved into position. With the pressure
in the collection tank now well above the vacuum level the outlet valve is
opened and normal operation is resumed. The control system will keep
cycling in the aforesaid manner without any manual manipulation as long as
a supply of filter media is available.
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The invention also provides a method for filtering deleterious
material from a liquid comprising the steps of:
supporting an elongated strip of filter media on a pervious means
formi.ng the bottom of a receiving tank;
providillg a collection tank below said receiving tank;
applying a suction force to said collection tank to reduce the
pressure therein and thereby increase the flow of clean liquid through said
filter media into said collection tank;
at a preselected lower pressure level in said collection tank due
to an accumulation of fi.ltered out material on said media causing a relative-
ly small auxiliary flow of clean liquid into said collection tank to sub-
stantially equali~e the pressure therein with the pressure in said receiving
tank;
thereafter pulling said filter media so that a layer of fresh media
is located between said receiving and collection tanks; and
returning said apparatus to its normal filtering mode.
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Advantages and features of the invention will become readily
apparent from the following detailed description of one embodiment which
is presented in conjunction with the accompanying drawing.
Brief Description of the Drawing
Figure 1 is a view in perspective of a filter apparatus embodying :
principles of the present invention with portions broken away to show
structural details;
Figure 2 is a view in side elevation of the filter apparatus of
Figure l;
Figure 3 is a top view of the filter apparatus of Figure 1 with
portions broken away;
Figure 4 $s an enlarged fragmentary view in section taken along
the line 4-4 of Figure 2;
Figure 5 is an enlarged fragmentary view in section showing the
intermediate rear wall and its sealing member;
Figure 6 is an enlarged view in side elevation showing the filter
media puller in greater detail;
Figure 7 is a partially schematic view in side elevation showing
the control system for the filter
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apparatus Or Figure l;
Figure S is a diagram for illustrating the operation of the control
system for the filter apparatus of Figure 7; and
Figure 9 is a view in side elevation of a modified form of filter
apparatus according to the invention including its control system shown
schematically; and
Figure 10 is a diagram for illustrating the sequential operation
of the control system for the filter apparatus of Figure 9.
Detailed Description of Embodiments
Referring to the drawing, Figure 1 shows a filter apparatus 20
which according to the invention, comprises generally a receiving tank 22
for dirty liquid to be filtered, located above a collection tank 24 for
clean, filtered liquid, both tanks being supported by a suitable frame 26.
The dirty liquid is furnished to the receiving tank through an inlet pipe 23
preferably having an end deflector. Separating these two tanks and forming
the bottom of the receiving tank is an inclined perforated grill plate 28
which supports a layer or strip of filter media 30 fed from a supply roll 32.
The collection tank under the inclined grill plate has an outlet conduit 34
connected to a suction pump (not shown in Figure 1), and its periphery is
sealed from the receiving tank. This enables reduced pressure to be main-
tained in the collection tank which induces greater flow through the filter
media and the supporting grill plate. The aforesaid sealing is accomplished
in part by clean liquid supplied from a storage reservoir 36 to elongated
fluid passage or chambers formed by sealing members 38 along the side edges
of the filter media. The entire sealing arrangement will be described in
greater detail later on.
Attached to the front end of the filter apparatus 20, adjacent the
upper end of the inclined grill plate is a guide or spreader roller 40 over
which the media passes. Below this roller the media is engaged by a puller
~; 30 device 42 for applying tension to the media to advance it along the inclined
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gril] plate. Tlle pul]cr clcvice coml)rises a crown roller 44 driven by an
axillly conllected motor 46 througll a reducing gear box 47 and a l~inch roller
48. Tle media from the spreader roller passes over and partially around the
crown roller and betweell it and the pinch roller.
The drive motor is activated by a control system to be described
later which functions to turn tlle crown roller and thereby advance the media
so that fresh media can be moved into place between the receiving and co]-
lection tanks. The used media loaded with filtered out material is dis-
pensed downwardly from the puller device into a suitable container for dis-
posal.
As shown in Figures 2 - 3 wherein the apparatus 20 is described
in greater detail the frame 26 is comprised of a pair of spaced apart up-
right members 50 and similar forward upright members 52 all of which may be
formed from rigid structural metal material such as elongated channel shaped
stock.
Attached to these frame members is a sheet metal body member having
vertical and triangular shaped side walls 54 interconnected by a sloping bot-
tom member 56.
In the embodiment of Figures 1 to 8 the outlet conduit 34 from
the collection tank is located at the end of a trough-like collector member
57 fixed to and extending transversely across the underside of the bottom
member 56 near its lowest point. A transverse slot 59 is provided in the
bottom member just above the collector member so that the filtered liquid
flowing through the media is gravity fed into it.
The side walls have a horizontal top edge with an outwardly extend-
ing strengthening flange 58 and they taper from a maximum height at the rear
or deep end to a much smaller height at the forward end. A rear wall member
60 encloses the rear end. Spaced inwardly from the rear wall member is an
intermediate wall member 62 that extends between side walls and forms the
storage reservoir 36 for clean liquid used in sealing the collection tank.
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Extendi~g between the side wa]ls and supported on the bottom member are
three cross frame members 64, 66 and 68. A rear cross frame memhcr 64 form-
ing the rear wall of the collection tanl; is located under the edge of the
intermediate wall member 62 and a forward cross member 68 extends between
the side walls at their narrow front ends. An intermediate cross member 66
spaced from the forward cross member approximately between the front upright
frame members forms the front end wall of the collection tank 24. The space
between the forward and intermediate cross members provide a drying chamber
for the filter media, designated by numeral 69.
Supported on the edge by the sloping bottom member 56 between the
rear and intermediate cross members and extending longitudinally thereon are
a series of steel strips 70 which are spaced apart but connected together by
a series of rods 72 to form a grate. This grate within the collection or
"vacuum" tank supports the sloping grill plate 28. This plate is preferably
formed from a strong durable and relatively rigid sheet material such as
aluminum provided with alternating ridges 74 and grooves 76 on its upper
surface. (See Figure 4). The ridges minimize contact area with the filter
media 30 thereon, and spaced apart within the adjacent grooves are a multi-
plicity of drilled or punched holes 78. A relatively short piece 28a of
grill plate providing a cover for the drying chamber extends between the
forward and intermediate cross members 66 and 68 and is supported on a sim-
ilarly short piece of grate comprised of steel strips 70a and metal rods
72_.
Fixed to each side wall 54, as shown in Figure 4 is a flat side
plate 80 whose upper surface is perpendicular to the side wall and co-planar
with the tops of the ridges 74 on the grill plate 28. Spaced above each
side plate is a guide member 38 in the form of a right angle structural mem-
ber whose vertical leg 82 is attached to the side wall. The horizontal leg
84 of each side sealing member is parallel to the side plate 80 spaced be-
low, and fixed to its underside near its outer end, as by a series of machine
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screws 86 is an elollgated sealing strip 88. The bottom face of this latterstrip is spaced jllst above the side plate so that there is enough clearance
to allow the edge of the filter media to move freely without excessive fric-
tion. A series of elongated grooves 90 are provided in the bottom face of
each strip 88 which form a labyrinth for clean sealing liquid. Thus, the
area bordered by the sealing strip 88, the side wall 54, tl-e sealing member
82 and the side plate 80 forms the cross section of a side chamber 92 which
communicates with the reservoir 36 for clean sealing liquid. Since the res-
ervoir is kept at a level higher than that of the receiving tank, the liquid
pressure within these side chambers 92 is greater. Thus, clean liquid cons-
tantly fills the labyrinth grooves 90 of the sealing strips and prevents any
migration of dirty liquid from the receiving tank around the side edges of
the filter media.
Fixed to the bottom of the intermediate wall 62, as shown in Fig-
ure 5, is a rear cross sealing member 94 also having a right angle cross sec-
tion. The vertical leg of this sealing member is fixed to the wall member
whose lower edge is positioned just above the surface of the filter media as
it enters into the receiving tank. Attached to the underside of the hori-
zontal leg 96 of the cross sealing member 94 is a sealing strip 97 having a
series of longitudinal grooves 98 on its bottom surface which function sim-
ilar to those on the side sealing strips 88. Thus, clean liquid from the
reservoir 36 is present under the intermediate wall member and fills the
grooves 98 to prevent any rearward migration of dirty liquid into the clean
reservoir.
The filter media 30 used with the apparatus 20 may be of any suit-
able type such as a commercially available paper type media having a thick-
ness in the range of .005 - .062 inches. The supply roll 32 of media is
mounted on a shaft which is journaled in bearings 102 fixed at some conven-
ient location on the frame or, as shown, to the top edges of the receiving
tank. The sheet of media from the supply roll extends downwardly into the
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clean liquid reservoir 36, around a guide roller 104 and under the intermed
iate wall 62 and Its grooved sealing member 94. The guide roller 104 is sup-
ported at its ends by a pair of bearings 106 fixed to the intermediate wall
62.
As shown in Figure 6, the ends of the spreader roller shaft are
supported in a pair of bearings 41 and the ends of the crown roller shaft
are supported in a pair of bearings 43. The latter bearings are fixed to
mounting plates 45 spaced apart and attached to the forward end of the appa-
ratus. 'I'he pinch roller 48 which has an outer layer of resilient material,
is urged against the crown roller 44 by an adjustable mechanism attached to
each mounting plate. The crown roller is preferably knurled on its outer
surface to provide a better grip on the paper. Each end of an axial shaft
49 for the pinch roller extends through an opening 51 in one mounting plate
45. Projecting transversely through each shaft end is a threaded pin 53. A
pair of collars 55 which are adjustable on this pin, are used to bear against
the opposite sides of the shaft 49 and thereby hold it in a preselected posi-
tion. By movement of these collars on the pin 53 the pinch roller can be
positioned tightly against the crown roller with the paper between these two
rollers. The pin is also connected to a toggle linkage 57 controllable by a
handle 59 so that when the paper is initially threaded, the pinch roller can
be quickly moved away from the crown ro]ler by an amount sufficient to pro-
vide adequate clearance for the paper. When the handle is moved back, the
pinch roller will return to its preadjusted position against the paper and
the crown roller.
The control system for the filter apparatus 20 is best described
with reference to Figure 7. As shown, the outlet conduit 34 from the col-
lection tank 24 is connected to the inlet side of a suction pump 112. The
outlet from this pump is connected to an outlet valve 114. A recirculating
feedback conduit 116 containing a relief valve 118 is provided between the
pump and the outlet valve. An outlet conduit 120 from the outlet valve
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furnishes clean filtered liquid to the processing machinery using it or to
a storage facility. Branching from this outlet conduit 120 is a conduit 122
connected to one side of the convergent-divergent passage of an eductor 124.
The other side of this eductor passage is connected to a conduit 126 that
extends into the reservoir 36 for clean liquid in the apparatus. A small
conduit 128 extends from the eductor 124 to the forward end of the collec-
tion tank where entrained air that is liberated from the filtered liquid is
more likely to accumulate. As will become apparent, the eductor 124 has
essentially three functions. First it removes from the collection tank the
liberated air which, if not eliminated, would cause the pump 112 to lose its
prime. Second, it supplies clean fluid to the reservoir 36, and third, it
functions to break the vacuum in the collection tank so that the paper can
be easily advanced.
Installed in this same forward end location within the collection
tank where the air accumulates is a pair of pressure switches 130 and 132.
The first pressure switch 130 is connected electrically to a solenoid 134
for operating an air valve 136 located near the outlet valve. This latter
air va]ve, supplied with air from a regulated pressure source (RA), has an
exhaust port and an outlet 138 connected to the diaphragm of the outlet
valve 114.
The first pressure switch is also connected electrically to the
second pressure switch which, in turn, is connected through a timing relay
140 to the motor 46 that drives the media puller device 42.
The operation of the filter apparatus 20 may be readily understood
by reference to Figures 7 and 8. As dirty liquid is supplied to the receiv-
ing tank 22, the suction pump 112 operates to provide a reduced pressure in
the collection tank 24 so that filtration takes place and the flow of clean
liquid through the filter media 30 is maintained at the maximum level.
~lean liquid from the outlet valve 114 is furnished through the outlet con-
duit 120 to the using process and also through the eductor 124 and into the
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reservoir 36. As filtered-out material builds up on the filter media within
the receiving tank the pressure in the collection tank will fall until it
reaches a predctermined level ~e.g. 5 psi absolute or -10 psi gage pressure).
At tllis point the first pressure switch 130 is activated and pulls in a
latching relay RL which, as indicated in the diagram of ~igure 8: (1) closes
a first pair of contacts RLl to activate the solenoid 134 and thus its valve
136, which closes the outlet valve 114; and (2) close a second pair of con-
tacts RL2 to supply power to the second pressure switch 132. The pump 112
continues to operate and with the out]et valve closed, the pump outlet pres-
sure opens the relief valve 118 in the feedback conduit 116 to allow recir-
culation through the pump.
Now, with the outlet valve closed and the pump recirculating liq-
uid through the conduit 116 and the relief valve, no liquid is flowing
through the conduit 122 and the eductor 124 into the reservoir. In fact,
the flow reverses in the eductor and by a siphoning action liquid flows from
the reservoir 36 through the conduit 128 back to the collection tank. This
immediately raises the pressure or breaks the near vacuum in the collection
tank which has the effect of removing the main friction or drag force on the
sides of the filter media strip 30.
As mentioned above, when the low pressure level was reached and
the first pressure switch 130 was activated it also supplied power to the
second pressure switch 132 through the latching relay contacts RL2 switch.
The second pressure switch is set to be activated at substantially the same
pressure level as in the dirty liquid tank 24. Therefore, when the reverse
flow in conduit 128 eliminates the near vacuum or suction condition in the
collection tank the pressure therein rises to the normal level, and the sec-
ond pressure switch 132, as indicated in Figure 8, supplies power through
the normally closed contacts RTl of the timing relay 140 to the media puller
drive motor 46. Since the vacuum has been eliminated in the collection tank
the frictional drag on the media is also reduced to the level where the
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media can be pulled easily by the puller 42. The timing relay causes the
motor to operate for a period of time (e.g. 3 to 5 seconds) that is long
enough for it to advance the media by a length sufficient to remove all the
used media and replace it with fresh media. At the end of this time period,
the normally closed contacts RTl are opened to stop the motor. When this
has taken place, a pair of auxiliary contacts RT2 on the timing relay close
to supply power to an un]atching coil RUL of the latching relay, thereby re-
storing all circuits to the filtering mode.
In the form of my invention just described the collection tank 24
is relatively small and it is intended that in an industrial system using
the filter 20 auxiliary storage tanks for clean liquid would be utilized to
assure ample flow of clean liquid during the brief down time period when the
filter media is being changed.
A modified form of the present invention is shown in Figure 9
wherein a filter apparatus 20a is provided with its own storage tank 140 for
clean liquid. This storage tank is located generally under the collection
tank 24 and is formed by downward extensions 142 of the side walls 54 which
extend below the bottom member 56. The upright frame members of the first
embodiment may be eliminated unless side wall stiffening is required and a
bottom member 143 of the storage tank may be supported on transverse sup-
ports 144. A forward wall 146 and an extended rear wall 148 connected to
the side wall extensions 142 complete the storage enclosure. The extended
rear wall 148 is spaced rearwardly from the original rear wall which thus
becomes a weir 60a for the clean liquid reservoir 36, having a top edge that
is slightly lower than that of the intermediate wall member 62a.
The storage reservoir 140 is provided with its own outlet 150. In
this embodiment, the outlet conduit 34 from the collection tank 24 and an
outlet conduit 152 from the reservoir outlet 150 are both connected to a
three-way valve 154. The outlet from this latter valve is connected to a
suction pump 112a, whose outlet furnishes clean liquid to the using machines
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through a conduit 120a. The diaphragm 155 for controlling this outlet
valve is connected to an air valve 156 having an air pressure inlet port
supplied from a regulated air source (RA), an exhaust port (Ex) and con-
trolled by a solenoid 158.
As in the previous embodiment, a branch conduit 160 from the pump
outlet conduit 120a extends through an eductor 124a to the clean liquid res-
ervoir 36. In this conduit 160, between the pump outlet conduit and the ed-
uctor is a shut-off valve 162 controlled by a second solenoid 164. As in
the first embodiment, a conduit 128a extends from the eductor 124a to the
forward end of the collection tank.
Also, as provided in the first embodiment, first and second pres-
sure switches 130a and 132a are provided within the collection tank. The
first switch 130a is connected electrically through a latching relay 131 to
the second switch 132a. It is also connected to the first solenoid 164 for
the eductor control valve 162, and to the second solenoid 158 for the 3-way
valve 156. The second pressure switch 132a is connected through a timing
relay 140a to the drive motor 46 for the filter media puller 42.
Operation of the filter 20a, as illustrated diagrammatically in
Figure 10, is similar to that of the filter 20 and as shown in Figure 8 ex-
cept for the use of liquid from the additional storage reservoir 140. Thisreservoir is initially filled by virtue of the fact that the weir 60a be-
tween the reservoir 36 and the storage tank 140 is lower than the intermed-
iate wall 62_ between the receiving tank and the reservoir 36. Thus, sur-
plus clean fluid passing through the eductor and into the reservoir 36,
flows over the weir into the storage tank until it is filled, and thereafter
it flows into the receiving tank.
Now, when the filter media becomes loaded with filtered out mate-
rial, the pressure within the collection tank continues to drop until it
reaches a predetermined level (e.g. 5 psi absolute or about 10 psi below
atmospheri.c pressure). At this point the first pressure switch 130a is
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activatcd to close the latching relay 131 which (1) furnishes power to the
second pressure switch ]32a; (2) activates the first solenoid 164 to close
the valve 162 in the branch conduit to the eductor 124a; and (3) activates
the second solenoid 158 to actuate the 3-way valve 156 that causes the pump
to draw clean liquid from the storage tank instead of the collection tank.
As with the filter 20, the flow in the eductor is now reversed due
to closure of the valve 162 and, as in the previous embodiment, fluid flows
in conduit 128a from the reservoir to the collection tank to eliminate the
negative pressure condition. When the pressure in the collection tank
reaches atmospheric (i.e. 14.7 psi), the second pressure switch 132a is ac-
tuated to furnish power through the timing relay 140a to the drive motor 46.
The motor then runs for the time period necessary (as preset by the timing
relay) to advance the required amount of fresh filter media.
The normal maximum time elapsed for a media advancing cycle as de-
scribed is aro~md 15 seconds. Since the storage tank can hold a supply of
clean liquid which will last, wlder normal demand, for arowld 15 to 20 min-
utes, there is an ample supply in the storage reservoir to assure continuous
service from the filter.
To those skilled in the art to which this invention relates, many
changes in construction and widely differing embodiments and applications of
the invention will suggest themselves without departing from the spirit and
scope of the invention. The disclosures and the description herein are
purely illustrative and are not intended to be in any sense limiting.
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