WO1997007869A1

WO1997007869A1 - Self-cleaning fluid filter unit

Info

Publication number: WO1997007869A1
Application number: PCT/US1996/013822
Authority: WO
Inventors: Lynn E. Cargill
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-08-29
Filing date: 1996-08-29
Publication date: 1997-03-06
Anticipated expiration: 1998-02-28
Also published as: EP0855931A4; EP0855931A1

Abstract

A high volume, self-cleaning filter unit (10) includes at least one cage support (18) with a downwardly angled surface having a direct path filter media (12) sealed thereto, with a suction source (14) to extract filtered fluid from the interior of the cage support (18). During operation of the filtering, particulates clog the filter media (12), and a backwashing (16) is effected by either backflushing with air or the fluid being filtered. Extremely high volumes of fluid can be filtered to a high degree, generally on the order of a few microns, in one step with a very economical filter unit (10). The downwardly angled surface holds the filter media (12) in such a position that a small mesh filter cloth is filtering a nominal size of particles out of the fluid. Oil is rejected by the filter unit (10) at a high rate, making this an effective oil/water separator as well.

Description

SELF-CLEANING FLUID FILTER UNIT

Technical Field

This invention relates to a filter unit for separating fluids from substance and particulates contained therein.

BACKGROUND OF THE INVENTION

There are many applications that require a self-cleaning fluid filter unit t separate fluids from substances and particulates which are contained therein, such a municipal water intake systems, dewatering operations to remove solids from liquids removing particulates from airflows, beverage processing, agricultural produc processing, the removal of ballast water contaminants as it is being pulled into th bilge tanks of a freighter, and mining operations. Prior art systems attempting t provide such a unit have used numerous types of filter paper, bag house systems, an many other filtration devices which all clog with the contaminants. There is a grea need for a system that will clean itself while providing a continuously flowing filtratio system. As technology has advanced, filtration systems are now able to filter ou smaller and smaller particles, although a penalty is being paid. Because these filtratio systems remove more and more particles, they clog faster and faster. Consequently it has been difficult to find a high volume system that did not clog readily.

Therefore, it would be an advantage to provide a high volume self cleaning filter unit which would be capable of continuously filtering fluids to remov and/or separate substances and particulates which are mixed in with the fluid.

It would also be advantageous to provide a high volume self-cleanin filter unit which would have a minimum of expenditure and would be sufficiently sma to in to enable retrofitting into existing systems where an investment has already been made.

It would also be an advantage to provide a prefilter in order to work in conjunction with further filter units that will remove finer and finer particles.

SUMMARY OF THE INVENTION

In accordance with the present invention, a high volume self-cleaning fluid filter unit is presented which will separate fluids from substances and particulates that are contained therein. The filter unit includes at least one enclosed cage support with spaced apart openings to allow the fluid to flow therethrough. The cage support shall have at least one downwardly angled surface for receiving direct path filter media that is sealed to the cage support for filtering the fluid. At least one passage out of the cage support can be attached to a suction source for withdrawing filtered fluid from within the cage support. In addition, the filter unit includes a means for backwashing the filter media to dislodge the particulates which have clogged the filter after operation. Further in accordance with the invention, there may also be included a means for providing a cross flow of fluid against the surface to wash away dislodged particles after backwashing has been effected. This will prevent the dislodged particles from immediately returning to the same clogging site that they had just been dislodged from.

In essence, in its simplest form, my fluid filter unit will be submerged into the fluid having the substances and particulates suspended therein, the suction source will be attached to the cage support and will draw the separated or cleaned fluid through the direct path filter media, out of the cage support, until the filter is either clogged or nearly clogged. At that point, the backwashing means will be effected and will dislodge the particulates that are embedded into the direct path filter media. If the situation warrants, it would be advantageous to provide a cross flow of fluid against the surface to wash away the dislodged particles before they have an opportunity to retum to their original site once the suction is resumed.

In the preferred embodiments, the cage support is either V-shaped, conical in shape, or will have one downwardly angled surface that is submerged into the fluid for cleaning. These configurations are especially well suited for municipal water intakes, dewatering of polluted ponds, removal of water from mining operations, recycling of dirty water in food processing stations, recycling of dirty water in car washes, and separation of oil and water in "pit" water tanks (where all the contaminated waters from factories are collected in one "pit").

The filter unit is also especially useful, in its preferred embodiments, as a prefilter for other treatments.

It acts as an economical, one-step treatment to take an absolutely filthy, contaminated water/oil/algae/sludge combination and to produce essentially pure non- smelly water, cleaned down to 15um, as fast as the pump is able. Then, an conventional final filtration method can be implemented in order to achieve potable water.

Furthermore, there may be additional cages that surround the cag support in order to help protect the filter media from being punctured by large objects, such as tree branches (in the case of a municipal water intake), or sharp objects (a in the case of mining operations). This exterior cage can be made of expanded meta or any other type of material that has relatively large openings, although smaller tha the expected offending items. ln addition, my filter unit can be used as a prefilter for activated carbon, resin, or reversed osmosis filtration in order to remove particulates or oil or other contaminants that are undesirable to the operations mentioned above. In that case, the effluent from my filter unit would act as the influent for the next type of filtration without the need for any intermediate filtration. As one can imagine, if the direct path filter media is a square weave monofilament fiber having 20um opening size.

my prefilter can be used to directly filter dirty river streams down to a 20um size, which would make the job of a further filtration, such as reverse osmosis much more effective, all in one single step.

While experimenting with the filter unit, I discovered that oil was rejected at a high rate. When a square weave, tightly woven 20um size filter media is used, the downwardly angled surface acts as a coalescer which separates oil from water. It appears that the square weave fiber mesh is taken to a uniquely nominal size, i.e. a 20um media may actually be performing as a 0.2um size mesh due to the angle that is achieved by the angled surface. If my filter unit is used to filter dirty pit water containing oil, algae, large leaves and organic matter as well as larger particulates, my filter unit can merely be submerged into the pit, and very clean water will be removed. In actuality, another unexpected result from this filtration unit was that in addition to rejecting oil, nearly all of the smell was removed from the filthy water, including the dead fish and diesel fuel smells that were present in the marina water that we filtered.

Referring again to the preferred embodiment of a V-shaped filter unit, a second filter cage can be overlaid over a first cage support, with the first cage support using a polyethylene square weave monofilament tightly woven fabric to a 20 micrometer (um) size, while the second cage support may utilize an electrically charged copper screen in order to repel metallic ions. Optionally, a single cage support could be used if the filter media was a combination of the polyethylene and the metal.

The filter media operates best when it has a direct path in order to catch particulates, and back washing is especially effective if there is a square weave or twill weave fabric that is utilized.

It appears that mγ filter unit works well in all fluids, as long as the filter media and cage support are made of materials which are compatible and chemically resistant to the fluid being filtered. In the case of dirty water, a plastic cage support and plastic filter media screen operate well. In the case of air filtration with caustic gases, a plastic cage support and filter media also operate well. In the instance of mining operations where the impinging pressures are much greater against the filter media and cage, I have found that it is best to use a metal cage support with a polyethylene filter media, although other rigid materials and resistant filter media may be utilized.

My filter unit will filter extremely high volumes of fluid due to the Bernoulli principle, in which the application of low pressure increases the flow. For instance, my two-sided 18"χ18" V-shaped filter unit utilizing 20um opening square weave polyethylene filter media in the cage support will filter over one million gallons of water in a day to a cleanliness of approximately 20um clean. A flow meter is attached to the outgoing fluid and as the flow slows down due to clogging, an air compressor which is attached as the backwashing means is activated, and compressed air is shot into the unit while it is submerged. This action will clean the filter media. If the filter is to be used in a river with a current, the river acts as a cross flow and as the air is shot into the unit and the clogging particulates are dislodged, -6- the river current sweeps away the dislodged particles before suction is reactivated. This acts to clean the filter and give nearly continuous filtration.

Therefore, in accordance with the present invention, there is disclosed a high volume self cleaning fluid filter unit that will substantially continuously filter the fluid and remove any substances or particulates that are mixed in with the fluid.

INDUSTRIAL USES

The filter unit of the present invention finds practical utility in both industrial, residential, commercial and mining operations. For example, municipal water manifold intakes, pond purification, pollution elimination, food processing, recycling of water, beverage processing, fish farming, dewatering of sludges and slurries, fire hose intakes, well water intakes, filtration of ballast water on freighters, and intake purifiers for personal watercraft as well as numerous other uses.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of the V-shaped filter unit constructed in accordance with the present invention;

FIG. 2 is a perspective cutaway of the cone-shaped filter unit of the present invention in the cyclone collection tank; FIG. 3 illustrates a tandem configuration of V-shaped filter units to maintain continuous filtration;

FIG. 4 shows a cone-shaped filter unit with suction from the bottom in a collection tank;

FIG. 5 shows a multi- V-shaped water configuration with a flotation device for large scale intakes;

FIG. 6 shows a filter unit being used in a pond type setting, as enclosed in a exterior cage for holding back seaweed and other lake items that prevent the filter from working;

FIG. 7a is a perspective view of the close-up operation during the suction mode;

FIG. 7b is a close up perspective view of the filter media during the backwashing operation;

FIG. 8 illustates a double cage support containing activated carbon or the like between the two cages; and

FIG. 9 shows the filter unit in a drag-out collection tank.

DETAILED DESCRIPTIONS OF THE DRAWINGS

Figure 1 illustrates the filter unit of the present invention and is generally denoted by the numeral 10. Filter unit 10 includes and enclosed cage support 18 with filter media 12 sealed to the cage support for filtering fluid that the filter unit 10 is submerged into. Suction source 14 withdraws filtered fluids from the interior region of the cage support. When a sufficient number of particulates have clogged filter media 12, the back washing means 16 is activated (in this figure as air hose hooked to an air compressor, and the back washing means applies pressure to the interior region of cage support 18 and back flushes particulates out of filter media 12. In this particular embodiment, the V-shaped cage support is illustrated. Filter media 12 can either be on one face or on both faces on the V-shaped configuration. Furthermore, the filter media is only applied on the downwardly facing surface. The entire filter 10 is tossed into the fluid which is to be filter whether that be water, oil or air. For the most part, this filter unit is submerged into dirty water which may include any other type of contaminant including oil and algae. The water that is withdrawn by pump 14 has been shown to be substantially cleaner than the water into which the filter unit has been submerged. Filter media 12 is preferable a square weave monofilament fiber

tightly woven polyethylene fabric. Although maximum flow rate is easily achieved with a twenty um mesh size, I have experimented with mesh sizes down to 0.2 um. For certain applications such as the water intakes for personal water craft the mesh size can be as large as 10 millimeters. The open weave design acts a direct path for particulates to be stopped and back flushed. This is in direct contradistinction to earlier designs which had membrane for the filter media and the membrane tortuous path. Consequently, back flushing was affective the first or second time, and was then rendered ineffective because the particulates became lodged in the tortuous path. It is also best if the filter media is non-sticky and chemically resistant to the fluid into which it is being dipped. Moreover, if a metallic screen, such copper or nickel is utilized, it can be electrically charged and used to repeal ions. Filter media 12 can also be a combination of metals, and synthetics.

The cage support 18 should have large opening to support the media in between. The downwardly angled surface is relative to the vertical axis of the unit. I have experimented with angles anywhere from 10 degrees to 90 degrees, and have found that the preferred range is from about 15 to 45 degrees. The cage support can be conical in shape as well as V-shaped. Furthermore, it can be tetrahedral o polygonal. The filtered media must be attached in, on, or under the cage support in such a manner that there is no leakage of the dirty fluid into the interior region of the enclosed cage support. This insures that as the suction source is applied that onl clean, filtered fluid is brought through the filter media. In the event of filtering air, the filtering unit is merely spender in a stream of dirty air and the suction source pulls clean air through the filter. The air compressor source 16 blows out the particulate after it has clogged filter media 12. These cage supports can applied in series such that a first filter unit is supplied with a filter media having a 1 ,000 um mesh with th effluent being pulled by suction source 14 acting as the influent to the next cag support that perhaps has filter media having a micron size of 20 um. This will act t successfully remove smaller and smaller particles.

In the preferred embodiment, for water intake applications, cage suppo 18 is made of ridged plastic or stainless steel so that is chemically resistant to dirt water and its containments after it has been submerged. In one embodiment, th entire face of the V-shaped water filter was made from expanded metal which gav a maximum net free open area and was completely covered by filter media 12. Filte media 12 was sealed to the edges with rubber gaskets and tightened down by a fac plate.

The back washing means is selected from compressed air, back flushin water, a hydraulic action by using a diaphragm pump that will push fluid back throug the pump to dislodge the particulates in the filter media. In its simplest form, an ai compressor from "shop air" is directly attached by a quick disconnect nozzle to th top of the filter unit. A flow meter attached to the suction source 14 triggers -10- switch when the flow becomes sufficiently low to pump air from the air compressor through air hose 16. This dislodges the particulates and "cleans" the water filter. Following the cleaning operation, suction is resumed and nearly continuous operation is effected. A self-priming pump is especially helpful in the use of the filter unit for filtering dirty water because the air that is injected into the body with stop a normal pump. However, if a tandem system which is illustrated in figure 3 is effected, then one filter unit can be in cleaning mode while the other one is in suction mode. Obviously, figure 3 should not be limited to a two unit system, and can be expanded to any number of units as long as there is a method for applying suction and cleaning modes alternatively. Any number of methods can be used to activate the cleaning versus suction modes including solenoids, mechanical switch, electrical switches, vacuum gages, timers, cycling valves, as well as various flow meters. One of ordinary skill in the art will be able to apply any number of these without undo experimentation.

For instance, it is envisioned for a municipal water intake, such as for the city of detroit, where approximately 125 million gallons a day are taken in, that perhaps there will be banks of ten (10) filter units, each capable of drawing in about five million gallons per day. In order to have continuous flow, there will be one out of the ten units in cleaning mode, while the remaining nine will be in suction mode.

Figures 1 and 3 both describe an "open" system. The open system is one in which clean fluid can be withdrawn from a dirty source. However, there are numerous instances in which the substances and particulates that are separated from the cleaned effluent need to be collected itself. In mining operations, where water is used to separate the gold from the dirt, the water is merely a vehicle for moving and separating the dirt from the gold. In that instance, the solid that remain on the outside of the filter unit are the desirable part, and need to be collected. In other D watering operations which include food processing, beverage processing (the removal of "charcoal filters" from beer), crushing operations, and other applications to numerous to list here have desirable screen size to withhold certain sizes of pieces. Furthermore, there may be a desirable screen size to allow only very fine pieces therethrough and it is been taken to yet another filter system to collect the size particles after they have come through the first filter unit with screen mesh.

In discussing the remainder of the figures, a general discussion of the suction source is necessary. Pumps are applied to the passage out of the cage support so that the filtered fluid is drawn through the filter cage rather that push through the piece of filter media. This sets up a situation where the bernoulli principle comes into play. As a low a pressure is applied to the inside via the suction source, the flow is increased by a factor of from about two to about one hundred. For instance, as will be seen later in the examples, my small unit which has a one square foot open filter media area, will filter over one million gallons a day with a strong trash pump. Furthermore, because the filter media is a screen at an angle, it appears that there is a coalescing action in play. Consequently, the 20 um mesh size actually is

uniquely nominally sized down to approximately 0.2 um. This has been proven out by the remove of much smaller particles than 20 um whether the suction is applied at the top or the bottom or the sides of any configuration of the filter unit, appears to be irrelevant. It seems to work no matter what direction the fluid is being pumped out of. The feature this filter unit so desirable is the incredible high volumes that are able to be achieved while filtering such small particles out of the fluid. Furthermore, the self cleaning feature provides essentially continuous operation.

Again, prior to further discussion of the drawings, a generally paragraph regarding the cross flow means is appropriate. Cross flow can be affected by gravity, a down flow, swirling (as in a cyclone), river currents, upflows and drafts, and water jets about the face of the unit. For instance, if the V-shaped filter unit of figure one has tapered sides so that it slides through the water much like a submarine and is dropped into a river with a heavy current. After the clogging has activated the back washing system, the river current will carry away the particles that have been dislodged by the back washing activity. In the case of closed units such as described in figure 2 and figure 4, a swirling is effected by using various means to get the water to go around in circles. This also allows the cleanest water to stay in the center of the circular tank such that the filter unit has a simpler job to do.

Closed systems are able to collect dirt so that water can be recirculated for a agricultural food processing and other instances where dirty water needs to be reused due to the low supply of fresh water. For example, tomatoes that are pick in the field have dirt leaves on them and must be washed before they can packed and sipped to grocery stores that dirt and pesticide combination with leaves must be removed. However, due to the nature of the location and the expense of water in Texas, Florida and areas where fresh water is not plentiful, it would be advantageous to recirculate the water in order to save a great deal of money. However, the dirt that is filtered out must be collected and removed. Therefore, I am proposing models for both my open and closed systems.

Referring now to figure 2, the filter unit is generally denoted by numeral 20, and is filled by a water supply 22. The cyclone tank 24 has a filter unit 26 submerged under the water. After it is submerged, suction source 28 begins to draw the clean water up through filter unit 26 and out of the unit. After it is clogged by particulate, air compressor 30 is activated and cleans the conically shaped filter unit 26. The dirt due to the swirling action of the water created by the water source 22 flings the heaviest dirt particles against the side of the cyclone tank while gravity alone works to force the heaviest particles down into takeout 32. Eventually, the dirt collects at the bottom of cyclone 24 and is removed by takeout 32.

Looking now to figure 4, there is shown a similar cyclone type filter unit generally denoted bγ numeral 60, and includes a conically shaped filter unit 66. In this embodiment, however pump 72 draws from the bottom of filter unit 66 while the water 62 is agitated within the tank bγ propeller or agitator arm 64. Dirt 68 goes against the sides of the cγclone tank and theγ concentrate gravitγ draws them down toward takeout 70.

Referring next to Figure 5, there is disclosed an open water floating filter unit 80 which includes multiple banks of V-shaped filter units 82 attached to a floatation device 84. All of filter units 82 are in open communication with Plenum 90. Air compressor intake 88 flushes out the filter units 82 after theγ have been clogged. Entire unit 80 is floated on top of water 78 and suction source 86 removes clean, filtered fluid through filter units 82. For instance, this has been attempted in pollution ponds that are created when multi acre sites of contaminants are mounded up, and the pollution ponds act as reservoirs for the rain run off. For instance, a near bγ fertilizer companγ has a gγpsum/phosphorous/arsenic/combination in a size of 160 acres that is 60 feet high. The rain run off produces approximatelγ 15 million gallons of contaminated water everγ γear. The companγ that ran the fertilizer needed a waγ to dewater the ponds and remove the solid contaminates.

In the marine environment, Figure 6 shows a filter unit generallγ denoted bγ 90, placed in a cage of expanded metal 94. Seaweed 96 is prevented from puncturing the filter media because the expanded metal cage helps to hold back the seaweed while the filter unit is working. The clean water spills in over the top of the cage at a sufficientlγ fast rate in order to keep up with suction source 92. The open area on the top of cage 94 is much, much greater than the area that has suction 92 applied to it.

Figures 7a and 7b show on microscopic laγer level the actual action during suction and back washing. The filter media is generallγ denoted bγ the numeral 100, with individual threats shown bγ 102. Particulates 104 are shown being drawn into and lodging in the square weave of figure 7a, while figure 7b shows the back washing effect.

Figure 8 illustrates a double cage sγstem of filter unit 120 with activated charcoal or resin or anγ number of other additives are placed between first cage support 122 and second cage support 124. Particles 126 indicate the activated carbon, etc.

Figure 9 illustrates a collection sγstem 130 for use with water filter 132. Bγ gravitγ, the dirtγ water can be placed into the tank and allow to drip over an edge into the area where the water filter 132 in withdrawing clean fluids. As the solution of dirt becomes more and more concentrated, the dirt is shown as falling down onto drag out 134 and the dirt is then being deposited into a bucket 136. This drag out mechanism is well know in the sewage and sludge arts, and finds great impeccabilitγ here.

Claims

What is Claimed is:

1. A high volume self-cleaning fluid filter unit for separating fluids from substances and particulates contained therein, comprising:

a) at least one enclosed cage support having an interior region and an exterior surface with spaced apart openings to allow fluid to flow therethrough, said at least one cage support having at least one downwardlγ angled surface;

b) direct path filter media sealed to the at least one cage support for filtering the fluid;

c) at least one passage out of the cage s u p p o r t adapted to be in communication with a suction source for withdrawing filtered fluid; and

d) a means for backwashing the filter media, said backwashing means being in communication with the interior cage support.

2. The filter unit of claim 1 , wherein said cage support includes at least one V-shaped cage.

3. The filter unit of claim 1 , wherein said cage support includes a conical-shaped cage.

4. The filter unit of claim 1 , wherein said cage support includes a one-sided cage support.

5. The filter unit of claim 1 , wherein said direct path filter media includes square weave woven fabric cloth.

6. The filter unit of claim 1 , wherein said filter media includes a woven mesh having mesh openings of from about 0.2 um to about 1 millimeter.

7. The filter unit of claim 1 , wherein said filter media includes monofilament woven fabric.

8. The filter unit of claim 1 , wherein said filter media includes woven fabric material selected from the group consisting of polγethγlene, nγlon, teflon, polγpropγlene, polγester, electricallγ chargeable metal, other metals, combinations of the sγnthetics and metals, and mixtures thereof.

9. The filter unit of claim 1 , wherein said means for backwashing includes compressed air.

10. The filter unit of claim 1 , wherein said means for backwashing includes water pressure.

1 1. A high volume self-cleaning fluid filter unit for separating fluids from substances and particulates contained therein, comprising: a) at least one enclosed cage support having an interior region and an exterior surface with spaced apart openings to allow fluid to flow therethrough, said at least one cage support having at least one downwardlγ angled surface;

c) at least one passage out of the cage support adapted to be in communication with a suction source for withdrawing filtered fluid;

d) a means for backwashing the filter media, said backwashing means being in communication with the interior cage support; and

e) a means for providing a cross flow of fluid against the surface to wash awaγ dislodged particulates after backwashing has been effected.

12. The filter unit of claim 1 1 , wherein said cross flow means includes a swirling cγclone to contain the filter unit and move water thereabouts.

13. A high volume self-cleaning fluid filter unit for separating fluids from substances and particulates contained therein, comprising: a) at least one enclosed cage support having an interior region and an exterior surface with spaced apart openings to allow fluid to flow therethrough, said at least one cage support having at least one downwardlγ angled surface;

e) a means for further filtering the withdrawn filtered fluid, said further filtering means being placed upstream and in¬ line from the cage support filter unit.

14. The filter unit of claim 13, wherein said further filtering is selected from the group consisting of finer mesh filter media, ultraviolet light, resin filtration, activated carbon filtration, and reverse osmosis.

15. A high volume self-cleaning water filter for separating oil from water, comprising: a.) at least one enclosed cage support having an interior region and an exterior surface with spaced part openings, said at least one cage support having at least one downwardlγ angled si-rface;

b.) direct path filter media sealed to the at least one cage support for filtering the water and oil combination;

c) at least one passage out of the cage support adapted to be in communication with a suction source for withdrawing filtered water; and

d) a means for backwashing the filter media, said backwashing means being in communication with the interior region of the cage support, said filter media being installed in the cage support, and the cage support having the downwardlγ angled surface such that the filter unit acts as a coalescer for separating the oil from the water and rejecting the oil, while allowing filtered water to pass therethrough.

16. The filter unit of claim 15, wherein the direct path filter media includes polγethγlene square weave tightlγ woven fabric.

17. The filter unit of claim 15, further comprising a means for providing a cross flow of fluid across the surface to wash awaγ anγ dislodged particulates after backwashing has been effected bγ the backwashing means.

18. The filter unit of claim 15, further comprising a swirling cγclone tank into which the filter unit is inserted in order to effect cross flow.