CA2499266C - Method and apparatus for filtering a liquid - Google Patents
Method and apparatus for filtering a liquid Download PDFInfo
- Publication number
- CA2499266C CA2499266C CA002499266A CA2499266A CA2499266C CA 2499266 C CA2499266 C CA 2499266C CA 002499266 A CA002499266 A CA 002499266A CA 2499266 A CA2499266 A CA 2499266A CA 2499266 C CA2499266 C CA 2499266C
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- CA
- Canada
- Prior art keywords
- filter media
- liquid
- filter
- main tank
- conical
- Prior art date
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
- B01D24/002—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with multiple filtering elements in parallel connection
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
- B01D24/02—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed stationary during the filtration
- B01D24/20—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed stationary during the filtration the filtering material being provided in an open container
- B01D24/26—Upward filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
- B01D24/46—Regenerating the filtering material in the filter
- B01D24/4668—Regenerating the filtering material in the filter by moving the filtering element
- B01D24/4689—Displacement of the filtering material to a compartment of the filtering device for regeneration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
- B01D24/48—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof integrally combined with devices for controlling the filtration
- B01D24/4807—Handling the filter cake for purposes other than regenerating
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Filtration Of Liquid (AREA)
Abstract
A filter comprises a main tank and at least two separate beds of particulate filter media contained in respective conical recipients integrated within the main tank so as to minimize the overall height and weight of the filter. A transport pipe is provided for each conical recipient in order to transport dirty filter media therefrom to a washing device in which the dirty filter media is washed as it flows downwardly in counter-current with a wash liquid. A filter media return pipe is provided for each conical recipient in order to return the cleaned filter media therein. The provision of multiple transport pipes and return pipes ensures efficient distribution of the filter media within the filter.
Description
METHOD AND APPARATUS
FOR FILTERING A LIQUID
BACKGROUND OF THE INVENTION
l.Field of the Invention The present invention relates to the treatment of liquids and, more particularly, pertains to a method and apparatus for filtering liquids.
FOR FILTERING A LIQUID
BACKGROUND OF THE INVENTION
l.Field of the Invention The present invention relates to the treatment of liquids and, more particularly, pertains to a method and apparatus for filtering liquids.
2. Description of the Prior Art It is well known to filtrate a liquid by supplying the same to a bed of particulate filter media contained in a tank having a truncated conical bottom end portion configured to prevent the farmation of stagnant or aead zones within the bed of particulate filter media. For instance, United States Patent No. 4, 126, 546 issued on November 21, 1978 to Hjelmner et al. discloses a sand filter comprising a main tank having a funnel-like shape bottom portion.
The geometry of the main tank results in the filter being relatively tall wr-Eich presents a number of disadvantages. The liquid to be filtered is delivered along a vertical direction into the sand and passed gradually upwardly theret:hrough to form a pool of filtrated liquid above tht~ top surface of the bed of sand. Deflectors must be provided to prevent particles of sand to come in direct contact with the outlet end of each delivery pipe used to supply the liquid to be treated. R single central transport device is provided to continuously convey dirty particles of sand from t~~e bottom of the tank to a washing device immersed in the pool of filtrated liquid. The dirty particles flows downwardly through a single annular wash path defined in the washing device in counter-current with a wash liquid before being recycle onto the top of the filter bed. A
deflector is provided underneath the washing device to distribute the cleaned particles of sand on the top surface of the filter bed.
Although the sand filter described in the above mentioned patent ~s effective, it has been found that there is a nE~ed for a more compact and lightweight filter which is adapted to provide an improved distribution of a particulate filter media.
SUMMARY OF THE INVENTION
It is therefore an aim of the present invention to provide ,=~ relatively compact and lightweight filter for filtering a liquid by causing it to flow through particulate filter media.
It is also an aim of the present invention to provide a filter which allows continuous washing of the particulate fiater media and effective distribution thereof.
It is a further aim of the present invention to provide an improved washing device for continuously washing dirty particles of filter media.
Therefore, in accordance with the present invention, there is provided a filter for filtering a liquid by causing the same to flow upwardly through a particulate filter media, comprising a main tank, at least two upstanding sub-i-ecipients integrated within the main tank for conta;.ning a particulate filter media adapted to fi:Lter a liquid seeping therethrough, inlet me;~ns for delivering and distributing the liquid ~.:~ be treated into the sub-recipients, and outlet means disposed above a top surface of the sub-recipients for discharging the liquid as a filtrated liduid. The provision of the sub-recipients allows to reduce the height of the filter.
In accordance with a further general aspect of the present inventi~7n there is provided an apparatus for filtering a liquid comprising a main tank, at least two laterally separate beds of particulate filter media contained in respective sub-recipients integrated within the main tank, inlet means for delivering a liquid to be treated into both sub-recipients, and outlet:: means for discharging the liquid which has seeped through the beds of filter media.
In accordance with a further general aspect of the present invention, there is provided a device for washing particulate filter media contaminated during filtration of a ~~iquid, comprising a hollow body defining a wash patr~, filter media inlet means for directing a flow of dirty filter media in a downward direction along the wash path, washing fluid inlet means for receivinc a flow of wash liquid in counter-current to the filter media along the wash path, and a plurality of axially spaced-apart arrays of agglomeration breaking members distributed along at least a portion of t.:he wash path, each array including a number of side-by-side agglomeration breaking members extending across the wash path.
BRIEF DESCRIPTION OF THE Dr~AWINGS
Having thus generally described the nature of the invention, referen.~e will now be made to the accompanying drawings, shc;wing by way of illustration a preferred embodiment thereof, and in which:
Fig. 1 is a schematic, simplified elevational view of an apparatus for filtering a liquid in accordance wi~:h a first embodiment of present invention;
Fig. 2 is a scruematic top plan view of a liquid delivery pipe network of the apparatus of Fig. l;
Fig. 3 is a schematic perspective view of a washing device forming pant of the apparatus of Fig.
l;
Fig. 4 is a schematic perspective view of the internal structure of the separator of Fig. 3;
The geometry of the main tank results in the filter being relatively tall wr-Eich presents a number of disadvantages. The liquid to be filtered is delivered along a vertical direction into the sand and passed gradually upwardly theret:hrough to form a pool of filtrated liquid above tht~ top surface of the bed of sand. Deflectors must be provided to prevent particles of sand to come in direct contact with the outlet end of each delivery pipe used to supply the liquid to be treated. R single central transport device is provided to continuously convey dirty particles of sand from t~~e bottom of the tank to a washing device immersed in the pool of filtrated liquid. The dirty particles flows downwardly through a single annular wash path defined in the washing device in counter-current with a wash liquid before being recycle onto the top of the filter bed. A
deflector is provided underneath the washing device to distribute the cleaned particles of sand on the top surface of the filter bed.
Although the sand filter described in the above mentioned patent ~s effective, it has been found that there is a nE~ed for a more compact and lightweight filter which is adapted to provide an improved distribution of a particulate filter media.
SUMMARY OF THE INVENTION
It is therefore an aim of the present invention to provide ,=~ relatively compact and lightweight filter for filtering a liquid by causing it to flow through particulate filter media.
It is also an aim of the present invention to provide a filter which allows continuous washing of the particulate fiater media and effective distribution thereof.
It is a further aim of the present invention to provide an improved washing device for continuously washing dirty particles of filter media.
Therefore, in accordance with the present invention, there is provided a filter for filtering a liquid by causing the same to flow upwardly through a particulate filter media, comprising a main tank, at least two upstanding sub-i-ecipients integrated within the main tank for conta;.ning a particulate filter media adapted to fi:Lter a liquid seeping therethrough, inlet me;~ns for delivering and distributing the liquid ~.:~ be treated into the sub-recipients, and outlet means disposed above a top surface of the sub-recipients for discharging the liquid as a filtrated liduid. The provision of the sub-recipients allows to reduce the height of the filter.
In accordance with a further general aspect of the present inventi~7n there is provided an apparatus for filtering a liquid comprising a main tank, at least two laterally separate beds of particulate filter media contained in respective sub-recipients integrated within the main tank, inlet means for delivering a liquid to be treated into both sub-recipients, and outlet:: means for discharging the liquid which has seeped through the beds of filter media.
In accordance with a further general aspect of the present invention, there is provided a device for washing particulate filter media contaminated during filtration of a ~~iquid, comprising a hollow body defining a wash patr~, filter media inlet means for directing a flow of dirty filter media in a downward direction along the wash path, washing fluid inlet means for receivinc a flow of wash liquid in counter-current to the filter media along the wash path, and a plurality of axially spaced-apart arrays of agglomeration breaking members distributed along at least a portion of t.:he wash path, each array including a number of side-by-side agglomeration breaking members extending across the wash path.
BRIEF DESCRIPTION OF THE Dr~AWINGS
Having thus generally described the nature of the invention, referen.~e will now be made to the accompanying drawings, shc;wing by way of illustration a preferred embodiment thereof, and in which:
Fig. 1 is a schematic, simplified elevational view of an apparatus for filtering a liquid in accordance wi~:h a first embodiment of present invention;
Fig. 2 is a scruematic top plan view of a liquid delivery pipe network of the apparatus of Fig. l;
Fig. 3 is a schematic perspective view of a washing device forming pant of the apparatus of Fig.
l;
Fig. 4 is a schematic perspective view of the internal structure of the separator of Fig. 3;
Fig. 5 is a schematic top plan view of the washing device shown in relation with the upper section of the apparatus of Fig. 1;
Fig. 6 is a schematic perspective view of a filtered liquid outlet ~tnd a waste liquid outlet provided at an upper end of the apparatus of Fig. 1;
Fig. 7 is a scl-:ematic perspective view of the waste liquid outlet;
Fig. 8 is a sc~~ematic perspective view of an end portion of a filter media return pipe of the washing device of Fig. 3;
Fig. 9 is a top plan view of a backwash system of the apparatus of Fig. 1;
Fig. 10 is a schematic, simplified elevational view of an apparatus for filtering a liquid in accordance with a second embodiment of the present invention;
Fig. 11 is a schematic top plan view of the apparatus of Fig. 10, illustrating the disposition of a washing device forming p:~rt of the apparatus;
Fig. 12 is a schematic perspective view of the internal structure c:f a part of the washing device;
Fig. 13 is an enlarged elevational view of a return pipe of the apparatus of Fig. 10;
Fig. 14 is a r~ransversal cross-sectional view taken along line 14-14 in Fig. 13; and Fig. 15 is a l..~ngitudinal cross-sectional view taken along line 15-1~i in Fig. 14.
DESCRIPTION OF THE PREFERR:~~D EMBODIMENTS
Now referring .o the drawings, and in particular to Fig. 1, an apparatus 10 for filtering a liquid, such as water, will be described. The apparatus 10 of the instant invention is particularly suitable for filtering water before being directed to an aqueduct. However, other applications are contemplated as well.
The apparatus 10 comprises a main tank 12 having a cylindrical side wall 14, a flat bottom wall 16 and a top wall 18. A secondary tank 20 having a cylindrical side wall 22 and an open bottom end 24 is mounted on the top wall 18 of the main tank 12. As seen in Fig. 6, the main tank 12 and the secondary tank 20 communicate together via a circular opening 26 defined in the top wall 18 of the main tank 12.
The main tank 12 and the wecondary tank 20 are formed of a thermoplastic material, such as polyethylene.
According to a preferred embodiment of the present invention, the secondary tank 20 is welded to the main tank 12. AlternativF.~ly, the secondary tank 20 and the main tank 12 could be integrally molded. A
lid (not shown) may be disposed on the top open end of the secondary tank 20 to prevent external agents from altering the filtered liquid contained in the secondary tank 20.
As seen in Fig. 2, a liquid delivery pipe network 28 is provided for discharging the liquid to be processed into the main tank 12. The liquid delivery pipe network 28 basically includes a manifold 30 having one inlet 32 and four outlets 34, each of which is connected to a valve 36 which in turn is connected to a delivery line 38. The inlet 32 of the manifold 30 is adapted to be connected to a source (not shown) of liquid to be processed. Each delivery line 38 is compo~>ed of a linear plastic pipe 40 connected to a curv:~d plastic pipe 42 having consecutive perpendicular portions 44 and 46. As seen in Fig. 1, the distal or bottom end of portion 46 of each curved pipe 42 is welded to the bottom wall 16 of the main tank 12. Each portion 46 is provided with a pair of lateral opposed outlets 48 through which the liquid to be treated is discharged in a horizontal direction. Such a multiple delivery piping system provides improved distribution of the liquid to be filtered, thereby contributing to enhance the overall efficiency of the filtration process.
As seen in Fig. 2, each vertical pipe portion 46 is received ~n a frusto-conical plastic recipient 50 having its smaller diameter end welded to the bottom wall 16 of the main tank 12. The frusto-conical recipients 50 extend upwardly from the bottom wall 16 above the lateral opposed outlets 48 up to approximately a thin-d of the height of the main tank 12. The inner spice of the frusto-conical recipients 50 around the pipe portions 46 is filled with a granular filter n;edia (not shown), such as sand. Accordingly, the lateral opposed outlets 48 through which the liquid to be processed is discharged are buried in the filter media. The provision of such fru~to-conical recipients 50 advantageously allows to reduce the overall height of the apparatus 10 by reducing the distance between the bottom of the tank 12 and the top surface of the bed of filter media for a given top surface of filter media. It is understood that the number of frusto-conical recipients varies with the size of the main reservoir 12.
According to a preferred embodiment of the instant invention, concrete is poured within the main tank 12 around the frusto-conical recipients 50 after the apparatus 10 has been shipped and installed at the appropriate location so as to prevent potential entrapment of stagnant wager within the main tank 12, which could result in un,:3esirable bacterial growth.
According to another embodiment of the present invention, the frusto-conical recipients 50 are integrally molded with th~~ main tank 12 so as to form the bottom wall 16 thereC.~f, thereby eliminating the need of pouring concrete within the main tank 12 in order to fill the space between the frusto-conical recipients 50.
In operation, the liquid to be treated is continuously supply into the filter media through the liquid delivery pipe netw<~rk 28, thereby forcing the liquid to rise in the filter media through seepage.
Eventually, the supplied liquid seeps up out of the granular filter media to form a pool of filtered liquid above the frusto-conical recipients 50 and the concrete. The level of filtered liquid is raised until it reaches the uppe~° end of the secondary tank 20 where the overflow of filtered liquid is collected via a filtered liquid outlet 52.
As seen in Fig. 6, the filtered liquid outlet 52 is essentially composed of a plastic box 54 welded to the outer surface of the cylindrical side wall 22 of the secondary tank 20 for receiving the overflow of filtered lquid passing through an opening 56 defined at the upper end of the cylindrical side wall 22 of the secondary tank 20.
The filtered liquid collected by the plastic box 54 is directed to a desired location via an outlet line 58 extending from an undersurface of the box 54.
As seen in Fig 1, the apparatus 10 further includes a filter media cleaning or washing system 60 adapted to be continuous-~y operated to prevent the filter media from being negatively altered by the liquid to be filtered. In other words, the filter media cleaning system 60 allows the filter media to substantially preserve its original condition, thereby ensuring the overall quality of the filtering process. The filter media cleaning system 60 essentially includes a source (not shown) of pressurized gas, such as sir, which is operational to force some liquid and fi:i.ter media to be displaced upwardly from the frusto-conical recipients 50 to a washing device 62 via four conduits 64 extending from the washing device 62 into respective ones of the frusto-conical recipients 50.
More specifically, each conduit 64 includes a first plastic pipe 67 and a second plastic pipe 66.
The plastic pipe 67 of each conduit 64 is connected at an upper end thereof to the source of pressurized gas to convey the gas into the filter media. The pipe 66 of each conduit 6~ defines a passage through which may flow the liquid and filter media. As seen in Fig. 1, the lower enc:~ portions of the pipes 66 extend into the pipes 46 of the unfiltered liquid delivery lines 38. It is noted that the liquid delivery lines 38 are configured to prevent the liquid to be treated to flaw past the outlets 48.
As seen in Figl. 1, 3 and 4, the washing device 62 is disposed oi.tside of the main tank 12 within the secondary tank 20 and includes a container 68 into which the conduits 64 extend for discharging filter media to be washed. A number of vertically spaced-apart arrays of transversally extending elongated members 70 are disposed below the fluid and filter media delivery end of the conduits 64 within the container 68 in order to break up aggregates of filter particles and to create a turbulence in the flow of filter media flowing therethrough by gravity to effect effective separation of the aggregated particles. As seen in Fig. 4, each array of elongated members includes a number of laterally spaced-apart elongated members 70 which are in offset relationship with the elongated mem~~ers 70 of the adjacent vertically spaced-apart axray. According to the first illustrated embodiment c:f the present invention, successive arrays alternately include four and five elongated members 70. Thke elongated members 70 are mounted at opposed ends thereof to a pair of support plates 72 which are in turn mounted to the inner surface of the container 68.
Four filter media return pipes 74 extend from the container 68, below the vertically spaced-_ g _ apart arrays of transversally extending elongated members 70, through the tap wall 18 of the main tank 12 for returning the granular or particulate filter media into respective frmsto-conical recipients 50.
Throughout their passage through the washing device 62, the filter particles encounter clean filtered liquid flowing upwardly ti~rough the returns pipes 74 from the immersed bottom ends thereof.
As seen in Figs. 1, 5 and 7, a waste liquid outlet 76 is connected to the washing device 62 via a pipe 78 for discharging the liquid which has been directed into the washing device 62.
More specifically, the waste liquid outlet 76 includes a plastic box 80 which is welded to the outer surface of the secondary tank 20 for receiving the waste liquid from the pipe 78, which extends through the cylindrical side wall 22 of the secondary tank 20. The waste or dirty liquid is evacuated from the box 80 through an cuatlet line 82 formed of a number of end-to-end plastic pipes extending downwardly from the bottrm wall 84 of the box 80. A
weir 86 extends upwardly from the bottom wall 84 of the box 80 upstream of the pipe 82 at an elevation which is at least equal tc: the pipe 78 to ensure that the waste fluid will pass from the washing device 62 to the waste liquid outlet 76 at an appropriate flow rate such as to allow the:: particles of filter media to sink in the washing device 62. Accordingly, the level of liquid within tY:e container 68 and the box 80 will be substantially equal.
In operation, pz~essurized gas is discharged through the lower end of the pipes 67 of the conduits 64 into the fi~.ter media and the liquid contained in the frusto-conical recipients 50, thereby giving rise to t~ze formation of bubbles. As the pressure within the passage deffined by the outer pipe 66 of each conduit 6~ is less than the pressure _ g -within the main tank 12, the bubbles escape through the passage of each conduit 64 bringing with them some filter media particles. Therefore, it can be said that the bubbles ha~.re a lifting effect on the particles of filter media.
At their exit t'rom the discharged end of the passages of the conduits 64, the bubbles come in contact with the liquid contained in the washing device 62. This results in the bursting of the bubbles, thereby allowing the filter media particles to flow down by gravity. ,~~ substantial portion of the liquid lift with the particles of filter media will be discharged through the waste liquid outlet 76 with little portion thereof flowing back into the main container 12 via the return pipes 74. The vertically spaced-apart arrays of transversally extending members 70 will promote turbulence, thereby causing the separation of the filter media particles. Indeed, as the filter particles are heavier they will sink, while the liquid will ter;d to remain trapped within the container 68 with the overflow being discharge through the waste liquid outlet 76. Accordingly, the particles of filter medi:~ will flow back into the frusto-conical recipients 50 via the return pipes 74.
The filtered liquid which flows upwardly through the return pipes 74 and iz2to the container 68 is discharged from the wash.~g device 62 via the waste liquid outlet 76. It is understood that the height of weir 86 can be varied t_:.~ control the quantity of liquid withdrawn from tree pool of filtered liquid contained in the main tank 12.
From the above, it can be appreciated that the filter media cleanzng system 60 allows to continuously clean the porous filter media even during the filtration of a supplied liquid.
As seen in Figs. 1 and 8, the lower end portion of each return pipe 74 defines a hole for receiving therethrough one of the conduits 64, thereby reducing the number of holes to be defined in the top wall 18 of the main tank 12.
Fig. 9 illust?rates a drain system 88 disposed on the bottom wall 16 of the main tank 12.
The drain system 88 includes a plurality of perforated drain pipes 90 which extend below the frusto-conical recipients 50 for collecting the liquid and particles to be drained. The drain pipes 90 are connected to a valve 92 for selectively allowing or blocking flaw through the perforated drain pipes 90.
One advantage of the present invention is that the apparatus 10 does not have to be pre-assembled before being shipped. The apparatus 10 may be readily assembled on site. Moreover, as almost all the principal components of ttve apparatus 10 are made of thermoplastic, the total weight thereof is considerably inferior to the weight of conventional steel filtering apparatus. The fact that the apparatus 10 is essentially made of thermoplastic, also prevents the same from being subject to corrosion.
Figs. 10 to 15 illustrate a second filter 110 similar to the first filter 10 but having an alternate washing device .60 mounted outwardly above a main tank 112 of the filter 110. The washing device 160 comprises a distribution box 194 including a cylindrical container 196 connected in flow communication with a zone of filtrated liquid in the main tank 112 via an upstanding pipe 198. The overflow of filtrated liquid is discharged from the main tank 112 via the upstanding pipe 198 as it flows over a weir 200 (see Fi<~,. 12) extending between a pair of parallel partiti~:an walls 202 extending in sealing engagement with an inner surface of the cylindrical container 19E~ to form with two other partition walls 204 and 206 a separate and isolated sub-compartment within the cylindrical container 196.
The filtrated liquid flowing over the weir 200 is conveyed to a desired lccation via an outlet line 158.
According to tree illustrated embodiment, the dirty filter media is delivered into the bottom portion of the cylindrical container 196 via four transport pipes 164 having respective upper ends spaced downwardly from th~> weir 200. As seen in Fig.
12, two pairs of diametrically opposed weirs 208 extends from the bottom wall 210 of the cylindrical tank 196 about an upper portion of the upstanding pipe 198 to divide th<~ bottom portion of the cylindrical container 19:; into four equal filter media receiving compartments 212. The dirty filter media is delivered int-:o the filter receiving compartments 212 by the transport pipes and flows downwardly back into the main tank 112 via four return pipes 174 extending downwardly from the bottom wall 210 of the cylindrical container 196. The bottom open end of each return pipe 174 is immersed in the filtrated liquid contained in the main tank 112 and is in vertical alignment with a corresponding conical recipient (not shown) int~~rated in the bottom of the main tank 112 to conta.n the particulate filter media, as explained with respect to the first embodiment of the present invention. Throughout their passage through the return pipes 174, the particles of filter media encounters a counter-current flow of filtrated liquid supplied to the washing device 160 through the immersed bott«m open ends of the return pipes 174. The filtrated liquid flowing upwardly into the washing device 160 is discharged through an outlet line 182 extending from the cylindrical container 196 at a location spaced downwardly from the weir 200. A pair of parallel weirs 214 extending from a bottom wall 216 between the partition wall 204 and the inner surface of the cylindrical container 196 regulates the flow of filtrated liquid withdrawn from the main tank 112.
As seen in Figs. 13 to 15, axially spaced apart arrays of agglomeration breaking members 170 are integrated in each of the return pipes 174. Each array includes a number of laterally spaced-apart agglomeration breaking members 170 extending across the fluid passage defined by the associated return pipe 174. The agglomeration breaking members 170 of adjacent arrays extend at right angles to each others. It has been fc~.znd that this arrangement provides improved separation of the agglomerated particles of filter media. The agglomeration breaking members 170 are provided in the form of elongated cylinders and are supported at opposed ends thereof in radial bores defined through the associated return pipes 174. A sleeve 218 is mounted on each return pipe 174 to prevent removal of the agglomeration breaking members 170.
As seen in Fig. 13, each set of arrays of agglomerating breaking members 170 is provided in a pipe segment 220 which fc:~rms an acute angle with a vertical axis. According to a preferred embodiment of the present invention this angle is about 35 degrees.
- 1.3 -
Fig. 6 is a schematic perspective view of a filtered liquid outlet ~tnd a waste liquid outlet provided at an upper end of the apparatus of Fig. 1;
Fig. 7 is a scl-:ematic perspective view of the waste liquid outlet;
Fig. 8 is a sc~~ematic perspective view of an end portion of a filter media return pipe of the washing device of Fig. 3;
Fig. 9 is a top plan view of a backwash system of the apparatus of Fig. 1;
Fig. 10 is a schematic, simplified elevational view of an apparatus for filtering a liquid in accordance with a second embodiment of the present invention;
Fig. 11 is a schematic top plan view of the apparatus of Fig. 10, illustrating the disposition of a washing device forming p:~rt of the apparatus;
Fig. 12 is a schematic perspective view of the internal structure c:f a part of the washing device;
Fig. 13 is an enlarged elevational view of a return pipe of the apparatus of Fig. 10;
Fig. 14 is a r~ransversal cross-sectional view taken along line 14-14 in Fig. 13; and Fig. 15 is a l..~ngitudinal cross-sectional view taken along line 15-1~i in Fig. 14.
DESCRIPTION OF THE PREFERR:~~D EMBODIMENTS
Now referring .o the drawings, and in particular to Fig. 1, an apparatus 10 for filtering a liquid, such as water, will be described. The apparatus 10 of the instant invention is particularly suitable for filtering water before being directed to an aqueduct. However, other applications are contemplated as well.
The apparatus 10 comprises a main tank 12 having a cylindrical side wall 14, a flat bottom wall 16 and a top wall 18. A secondary tank 20 having a cylindrical side wall 22 and an open bottom end 24 is mounted on the top wall 18 of the main tank 12. As seen in Fig. 6, the main tank 12 and the secondary tank 20 communicate together via a circular opening 26 defined in the top wall 18 of the main tank 12.
The main tank 12 and the wecondary tank 20 are formed of a thermoplastic material, such as polyethylene.
According to a preferred embodiment of the present invention, the secondary tank 20 is welded to the main tank 12. AlternativF.~ly, the secondary tank 20 and the main tank 12 could be integrally molded. A
lid (not shown) may be disposed on the top open end of the secondary tank 20 to prevent external agents from altering the filtered liquid contained in the secondary tank 20.
As seen in Fig. 2, a liquid delivery pipe network 28 is provided for discharging the liquid to be processed into the main tank 12. The liquid delivery pipe network 28 basically includes a manifold 30 having one inlet 32 and four outlets 34, each of which is connected to a valve 36 which in turn is connected to a delivery line 38. The inlet 32 of the manifold 30 is adapted to be connected to a source (not shown) of liquid to be processed. Each delivery line 38 is compo~>ed of a linear plastic pipe 40 connected to a curv:~d plastic pipe 42 having consecutive perpendicular portions 44 and 46. As seen in Fig. 1, the distal or bottom end of portion 46 of each curved pipe 42 is welded to the bottom wall 16 of the main tank 12. Each portion 46 is provided with a pair of lateral opposed outlets 48 through which the liquid to be treated is discharged in a horizontal direction. Such a multiple delivery piping system provides improved distribution of the liquid to be filtered, thereby contributing to enhance the overall efficiency of the filtration process.
As seen in Fig. 2, each vertical pipe portion 46 is received ~n a frusto-conical plastic recipient 50 having its smaller diameter end welded to the bottom wall 16 of the main tank 12. The frusto-conical recipients 50 extend upwardly from the bottom wall 16 above the lateral opposed outlets 48 up to approximately a thin-d of the height of the main tank 12. The inner spice of the frusto-conical recipients 50 around the pipe portions 46 is filled with a granular filter n;edia (not shown), such as sand. Accordingly, the lateral opposed outlets 48 through which the liquid to be processed is discharged are buried in the filter media. The provision of such fru~to-conical recipients 50 advantageously allows to reduce the overall height of the apparatus 10 by reducing the distance between the bottom of the tank 12 and the top surface of the bed of filter media for a given top surface of filter media. It is understood that the number of frusto-conical recipients varies with the size of the main reservoir 12.
According to a preferred embodiment of the instant invention, concrete is poured within the main tank 12 around the frusto-conical recipients 50 after the apparatus 10 has been shipped and installed at the appropriate location so as to prevent potential entrapment of stagnant wager within the main tank 12, which could result in un,:3esirable bacterial growth.
According to another embodiment of the present invention, the frusto-conical recipients 50 are integrally molded with th~~ main tank 12 so as to form the bottom wall 16 thereC.~f, thereby eliminating the need of pouring concrete within the main tank 12 in order to fill the space between the frusto-conical recipients 50.
In operation, the liquid to be treated is continuously supply into the filter media through the liquid delivery pipe netw<~rk 28, thereby forcing the liquid to rise in the filter media through seepage.
Eventually, the supplied liquid seeps up out of the granular filter media to form a pool of filtered liquid above the frusto-conical recipients 50 and the concrete. The level of filtered liquid is raised until it reaches the uppe~° end of the secondary tank 20 where the overflow of filtered liquid is collected via a filtered liquid outlet 52.
As seen in Fig. 6, the filtered liquid outlet 52 is essentially composed of a plastic box 54 welded to the outer surface of the cylindrical side wall 22 of the secondary tank 20 for receiving the overflow of filtered lquid passing through an opening 56 defined at the upper end of the cylindrical side wall 22 of the secondary tank 20.
The filtered liquid collected by the plastic box 54 is directed to a desired location via an outlet line 58 extending from an undersurface of the box 54.
As seen in Fig 1, the apparatus 10 further includes a filter media cleaning or washing system 60 adapted to be continuous-~y operated to prevent the filter media from being negatively altered by the liquid to be filtered. In other words, the filter media cleaning system 60 allows the filter media to substantially preserve its original condition, thereby ensuring the overall quality of the filtering process. The filter media cleaning system 60 essentially includes a source (not shown) of pressurized gas, such as sir, which is operational to force some liquid and fi:i.ter media to be displaced upwardly from the frusto-conical recipients 50 to a washing device 62 via four conduits 64 extending from the washing device 62 into respective ones of the frusto-conical recipients 50.
More specifically, each conduit 64 includes a first plastic pipe 67 and a second plastic pipe 66.
The plastic pipe 67 of each conduit 64 is connected at an upper end thereof to the source of pressurized gas to convey the gas into the filter media. The pipe 66 of each conduit 6~ defines a passage through which may flow the liquid and filter media. As seen in Fig. 1, the lower enc:~ portions of the pipes 66 extend into the pipes 46 of the unfiltered liquid delivery lines 38. It is noted that the liquid delivery lines 38 are configured to prevent the liquid to be treated to flaw past the outlets 48.
As seen in Figl. 1, 3 and 4, the washing device 62 is disposed oi.tside of the main tank 12 within the secondary tank 20 and includes a container 68 into which the conduits 64 extend for discharging filter media to be washed. A number of vertically spaced-apart arrays of transversally extending elongated members 70 are disposed below the fluid and filter media delivery end of the conduits 64 within the container 68 in order to break up aggregates of filter particles and to create a turbulence in the flow of filter media flowing therethrough by gravity to effect effective separation of the aggregated particles. As seen in Fig. 4, each array of elongated members includes a number of laterally spaced-apart elongated members 70 which are in offset relationship with the elongated mem~~ers 70 of the adjacent vertically spaced-apart axray. According to the first illustrated embodiment c:f the present invention, successive arrays alternately include four and five elongated members 70. Thke elongated members 70 are mounted at opposed ends thereof to a pair of support plates 72 which are in turn mounted to the inner surface of the container 68.
Four filter media return pipes 74 extend from the container 68, below the vertically spaced-_ g _ apart arrays of transversally extending elongated members 70, through the tap wall 18 of the main tank 12 for returning the granular or particulate filter media into respective frmsto-conical recipients 50.
Throughout their passage through the washing device 62, the filter particles encounter clean filtered liquid flowing upwardly ti~rough the returns pipes 74 from the immersed bottom ends thereof.
As seen in Figs. 1, 5 and 7, a waste liquid outlet 76 is connected to the washing device 62 via a pipe 78 for discharging the liquid which has been directed into the washing device 62.
More specifically, the waste liquid outlet 76 includes a plastic box 80 which is welded to the outer surface of the secondary tank 20 for receiving the waste liquid from the pipe 78, which extends through the cylindrical side wall 22 of the secondary tank 20. The waste or dirty liquid is evacuated from the box 80 through an cuatlet line 82 formed of a number of end-to-end plastic pipes extending downwardly from the bottrm wall 84 of the box 80. A
weir 86 extends upwardly from the bottom wall 84 of the box 80 upstream of the pipe 82 at an elevation which is at least equal tc: the pipe 78 to ensure that the waste fluid will pass from the washing device 62 to the waste liquid outlet 76 at an appropriate flow rate such as to allow the:: particles of filter media to sink in the washing device 62. Accordingly, the level of liquid within tY:e container 68 and the box 80 will be substantially equal.
In operation, pz~essurized gas is discharged through the lower end of the pipes 67 of the conduits 64 into the fi~.ter media and the liquid contained in the frusto-conical recipients 50, thereby giving rise to t~ze formation of bubbles. As the pressure within the passage deffined by the outer pipe 66 of each conduit 6~ is less than the pressure _ g -within the main tank 12, the bubbles escape through the passage of each conduit 64 bringing with them some filter media particles. Therefore, it can be said that the bubbles ha~.re a lifting effect on the particles of filter media.
At their exit t'rom the discharged end of the passages of the conduits 64, the bubbles come in contact with the liquid contained in the washing device 62. This results in the bursting of the bubbles, thereby allowing the filter media particles to flow down by gravity. ,~~ substantial portion of the liquid lift with the particles of filter media will be discharged through the waste liquid outlet 76 with little portion thereof flowing back into the main container 12 via the return pipes 74. The vertically spaced-apart arrays of transversally extending members 70 will promote turbulence, thereby causing the separation of the filter media particles. Indeed, as the filter particles are heavier they will sink, while the liquid will ter;d to remain trapped within the container 68 with the overflow being discharge through the waste liquid outlet 76. Accordingly, the particles of filter medi:~ will flow back into the frusto-conical recipients 50 via the return pipes 74.
The filtered liquid which flows upwardly through the return pipes 74 and iz2to the container 68 is discharged from the wash.~g device 62 via the waste liquid outlet 76. It is understood that the height of weir 86 can be varied t_:.~ control the quantity of liquid withdrawn from tree pool of filtered liquid contained in the main tank 12.
From the above, it can be appreciated that the filter media cleanzng system 60 allows to continuously clean the porous filter media even during the filtration of a supplied liquid.
As seen in Figs. 1 and 8, the lower end portion of each return pipe 74 defines a hole for receiving therethrough one of the conduits 64, thereby reducing the number of holes to be defined in the top wall 18 of the main tank 12.
Fig. 9 illust?rates a drain system 88 disposed on the bottom wall 16 of the main tank 12.
The drain system 88 includes a plurality of perforated drain pipes 90 which extend below the frusto-conical recipients 50 for collecting the liquid and particles to be drained. The drain pipes 90 are connected to a valve 92 for selectively allowing or blocking flaw through the perforated drain pipes 90.
One advantage of the present invention is that the apparatus 10 does not have to be pre-assembled before being shipped. The apparatus 10 may be readily assembled on site. Moreover, as almost all the principal components of ttve apparatus 10 are made of thermoplastic, the total weight thereof is considerably inferior to the weight of conventional steel filtering apparatus. The fact that the apparatus 10 is essentially made of thermoplastic, also prevents the same from being subject to corrosion.
Figs. 10 to 15 illustrate a second filter 110 similar to the first filter 10 but having an alternate washing device .60 mounted outwardly above a main tank 112 of the filter 110. The washing device 160 comprises a distribution box 194 including a cylindrical container 196 connected in flow communication with a zone of filtrated liquid in the main tank 112 via an upstanding pipe 198. The overflow of filtrated liquid is discharged from the main tank 112 via the upstanding pipe 198 as it flows over a weir 200 (see Fi<~,. 12) extending between a pair of parallel partiti~:an walls 202 extending in sealing engagement with an inner surface of the cylindrical container 19E~ to form with two other partition walls 204 and 206 a separate and isolated sub-compartment within the cylindrical container 196.
The filtrated liquid flowing over the weir 200 is conveyed to a desired lccation via an outlet line 158.
According to tree illustrated embodiment, the dirty filter media is delivered into the bottom portion of the cylindrical container 196 via four transport pipes 164 having respective upper ends spaced downwardly from th~> weir 200. As seen in Fig.
12, two pairs of diametrically opposed weirs 208 extends from the bottom wall 210 of the cylindrical tank 196 about an upper portion of the upstanding pipe 198 to divide th<~ bottom portion of the cylindrical container 19:; into four equal filter media receiving compartments 212. The dirty filter media is delivered int-:o the filter receiving compartments 212 by the transport pipes and flows downwardly back into the main tank 112 via four return pipes 174 extending downwardly from the bottom wall 210 of the cylindrical container 196. The bottom open end of each return pipe 174 is immersed in the filtrated liquid contained in the main tank 112 and is in vertical alignment with a corresponding conical recipient (not shown) int~~rated in the bottom of the main tank 112 to conta.n the particulate filter media, as explained with respect to the first embodiment of the present invention. Throughout their passage through the return pipes 174, the particles of filter media encounters a counter-current flow of filtrated liquid supplied to the washing device 160 through the immersed bott«m open ends of the return pipes 174. The filtrated liquid flowing upwardly into the washing device 160 is discharged through an outlet line 182 extending from the cylindrical container 196 at a location spaced downwardly from the weir 200. A pair of parallel weirs 214 extending from a bottom wall 216 between the partition wall 204 and the inner surface of the cylindrical container 196 regulates the flow of filtrated liquid withdrawn from the main tank 112.
As seen in Figs. 13 to 15, axially spaced apart arrays of agglomeration breaking members 170 are integrated in each of the return pipes 174. Each array includes a number of laterally spaced-apart agglomeration breaking members 170 extending across the fluid passage defined by the associated return pipe 174. The agglomeration breaking members 170 of adjacent arrays extend at right angles to each others. It has been fc~.znd that this arrangement provides improved separation of the agglomerated particles of filter media. The agglomeration breaking members 170 are provided in the form of elongated cylinders and are supported at opposed ends thereof in radial bores defined through the associated return pipes 174. A sleeve 218 is mounted on each return pipe 174 to prevent removal of the agglomeration breaking members 170.
As seen in Fig. 13, each set of arrays of agglomerating breaking members 170 is provided in a pipe segment 220 which fc:~rms an acute angle with a vertical axis. According to a preferred embodiment of the present invention this angle is about 35 degrees.
- 1.3 -
Claims (3)
1. A device for washing particulate filter media contaminated during filtration of a liquid, comprising a hollow body defining a wash path, filter media inlet means for directing a flow of dirty filter media in a downward direction along said wash path, washing fluid inlet means for receiving a flow of wash liquid in counter-current to the filter media along said wash path, and a plurality of axially spaced-apart arrays of agglomeration breaking members distributed along at least a portion of said wash path, each said array including a number of side-by-side agglomeration breaking members extending across said wash path.
2. A device as defined in claim 1, wherein the agglomeration breaking members of adjacent arrays are disposed at right angles with respect to each others.
3. A device as defined in claim 2, wherein each said agglomeration breaking member is provided in the form of an elongated cylindrical member.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002499266A CA2499266C (en) | 1999-01-21 | 1999-11-30 | Method and apparatus for filtering a liquid |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2260178 | 1999-01-21 | ||
| CA2,260,178 | 1999-01-21 | ||
| CA002291336A CA2291336C (en) | 1999-01-21 | 1999-11-30 | Method and apparatus for filtering a liquid |
| CA002499266A CA2499266C (en) | 1999-01-21 | 1999-11-30 | Method and apparatus for filtering a liquid |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002291336A Division CA2291336C (en) | 1999-01-21 | 1999-11-30 | Method and apparatus for filtering a liquid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2499266A1 CA2499266A1 (en) | 2000-07-21 |
| CA2499266C true CA2499266C (en) | 2006-10-31 |
Family
ID=31888833
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002291336A Expired - Fee Related CA2291336C (en) | 1999-01-21 | 1999-11-30 | Method and apparatus for filtering a liquid |
| CA002499266A Expired - Fee Related CA2499266C (en) | 1999-01-21 | 1999-11-30 | Method and apparatus for filtering a liquid |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002291336A Expired - Fee Related CA2291336C (en) | 1999-01-21 | 1999-11-30 | Method and apparatus for filtering a liquid |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA2291336C (en) |
-
1999
- 1999-11-30 CA CA002291336A patent/CA2291336C/en not_active Expired - Fee Related
- 1999-11-30 CA CA002499266A patent/CA2499266C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2291336A1 (en) | 2000-07-21 |
| CA2499266A1 (en) | 2000-07-21 |
| CA2291336C (en) | 2006-02-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20151130 |