FILTRATION APPARATUS

Abstract

A filtration apparatus for treating a fluid comprises a vessel, a first partition plate dividing the vessel into first and second chambers and defining a through hole, and a filtration module located within the second chamber and including a body section defining an outer diameter which is greater than the diameter of the through hole in the first partition plate. The apparatus further comprises a reducing connector having a first end secured to the body section of the filtration module and a second end sealed relative to the through hole in the first partition plate to permit communication between the filtration module and the first chamber.

In a disclosed embodiment the apparatus includes a second partition plate such that the vessel is divided into first, second and third chambers, wherein the filtration module is mounted between the partition plates.

Claims

1. A filtration apparatus for treating a fluid, comprising: a vessel; a first partition plate defining a through hole; a second partition plate, wherein the first and second partition plates divide the vessel into first, second and third chambers; a filtration module located within the second chamber and including a body section defining an outer width which is greater than the width of the through hole in the first partition plate; and a reducing connector having a first end secured to the body section of the filtration module and a second end sealed relative to the through hole in the first partition plate to permit communication between the filtration module and the first chamber.

2. The apparatus according to claim 1, wherein the reducing connector defines a permeate outlet of the filtration module.

3. The apparatus according to claim 1, wherein the reducing connector comprises: a first portion for securing to the body section of the filtration module; a second portion which defines a smaller width than the first portion and is sealed relative to the through hole; and a tapered portion extending between the first and second portions.

4. The apparatus according to claim 1, wherein at least a portion of the reducing connector superposes the through hole and is sealed relative to a surface of the first partition plate around the periphery of the through hole.

5. The apparatus according to claim 1, wherein at least a portion of the reducing connector extends into the through hole in the first partition plate and is sealed relative to an internal surface of the through hole.

6. The apparatus according to claim 1, wherein the reducing connector is secured to the first partition plate by a bolt which extends from one side of the first partition plate to engage the reducing connector on the opposite side of the first partition plate and clamp the reducing connector against the first partition plate.

7. The apparatus according to claim 6, wherein the bolt defines an axial through bore such that when the bolt is connected with the reducing connector fluid communication through the through bore of the bolt is permitted, and fluid communication between the filtration module and the first chamber within the vessel is achieved via the through bore in the bolt.

8. The apparatus according to claim 1, wherein the filtration module comprises an outer shroud, and the reducing connector is secured to the shroud.

9. The apparatus according to claim 8, wherein the shroud comprises one or more ports to permit fluid communication between external and internal regions of the shroud.

10. The apparatus according to claim 1, wherein the second partition plate defines a through hole and an inlet of the filtration module is sealed relative to said through hole to permit communication between the filtration module and the third chamber.

11. The apparatus according to claim 10, wherein the through hole in the second partition plate defines a smaller width than the outer width of the filtration module.

12. The apparatus according to claim 10, comprising a further reducing connector having a first end secured to the body section of the filtration module and a second end sealed relative to the through hole in the second partition plate.

13. The apparatus according to claim 10, comprising a tubular member extending from the through hole in the second partition plate into the third chamber and providing communication between the third chamber and the filtration module.

14. The apparatus according to claim 13, wherein at least one of: the tubular member defines an open end to facilitate communication of a fluid from the third chamber into the tubular member; and the tubular member defines a port in an outer surface thereof to facilitate communication of gas from the third chamber and into the tubular member.

15. A method for cleaning a filtration apparatus which includes a vessel with first, second and third chambers and a filtration module located within the second chamber, comprising: flowing a cleaning fluid into the third chamber; flowing the cleaning fluid from the third chamber and into the filtration module; flowing the cleaning fluid across the surface of a filtration membrane contained within the filtration module; and flowing the fluid from the filtration module and into the second chamber.

16. The method according to claim 15, comprising: flowing a backwash cleaning fluid from the first chamber and into the filtration module; flowing the backwash cleaning fluid through the module; and flowing the backwash fluid from the filtration module and into the second chamber.

17. The method according to claim 15, comprising passing a gas through the filtration module to scour the membrane.

18. A method for manufacturing a filtration apparatus, comprising: securing a filtration module relative to a partition plate, wherein the partition plate defines a through hole which is smaller than the width of a body portion of the filtration module; and mounting the partition plate within a vessel.

19. The method according to claim 18, comprising: securing the filtration module relative to a second partition plate, wherein the second partition plate defines a through hole which is smaller than the width of the body portion of the filtration module; and mounting the second partition plate within the vessel.

20. The method according to claim 18, wherein at least one of the partition plates is mounted within the vessel before, during or after the filtration module is secured to said at least one of the partition plates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0177] These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0178] FIG. 1 is a cross sectional view of a filtration apparatus:

[0179] FIG. 2 illustrates a filtration module for use within a filtration apparatus of FIG. 1;

[0180] FIGS. 3a and 3b provide enlarged cross-sectional views of upper and lower ends, respectively, of the filtration module of FIG. 3 shown connected within the apparatus;

[0181] FIG. 4 provides a piping and instrumentation diagram of a filtration system which may include the filtration apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

[0182] A filtration apparatus, generally identified by reference numeral 10, is shown in FIG. 1 and includes a vessel 12, illustrated in cross-section, and formed of a central cylindrical section 12a and upper and lower domed cap sections 12b, 12c mounted to opposing ends of the central section 12a via respective flange joints 14, 16. Upper and lower partition plates 18, 20 are mounted within the vessel 12 to define upper, lower and intermediate chambers 22, 24, 26. The periphery of the upper partition plate 18 is clamped and sealed between the central and upper cap sections 12a, 12b of the vessel 12 at the region of flange joint 14. Similarly, the periphery of the lower partition plate 20 is clamped and sealed between the central and lower cap sections 12a, 12c of the vessel 12 at the region of flange joint 16.

[0183] The apparatus 10 comprises a plurality of filtration modules 30 located within the intermediate chamber 26 and mounted between the upper and lower partition plates 18, 20. The modules 30 each include one or more filtration membranes (not illustrated) mounted therein. The type of filtration achieved is determined by the membrane type, and may include size exclusion, for example by use of micro and ultra filtration membranes, and/or ionic selection or rejection, for example by use of nano filtration and reverse osmosis membranes. In some embodiments perhaps between 2 and 65 filtration modules may be provided, for example between 30 and 40 modules, such as 38 modules, although any suitable number may be provided depending on the specific application, available space and the like. Further, in some embodiments a membrane area of between 10 and 100 m.sup.2 may be provided in each module. In one embodiment each module may comprise between 40 and 50 m.sup.2 of membrane filtering surface area, for example around 44 m.sup.2 of filtering surface area. It should be noted that some filtration modules are not illustrated in FIG. 1 for clarity purposes.

[0184] Reference is now additionally made to FIGS. 2, 3a and 3b, wherein FIG. 2 provides an enlarged view of an individual filtration module 30, FIG. 3a provides a still larger cross sectional view of the upper region of the filtration module 30 shown engaged with the upper partition plate 18, and FIG. 3b provides an enlarged cross-sectional view of the lower region of the filtration module 30 shown engaged with the lower partition plate 20.

[0185] Each filtration module 30 comprises an elongate body section 32 which includes an outer tubular shroud 34 enclosing the filtration membranes, and upper and lower reducing connectors 36, 38 secured to respective ends of the shroud 34. The connectors 36, 38 may be secured to the shroud 34 by, for example, threaded connection, adhesive bonding or the like.

[0186] The reducing connectors 36, 38 permit engagement of the filtration module 30 with the upper and lower partition plates 18, 20. In particular, the upper connector 36 of each filtration module 30 is sealingly engaged relative to a respective through hole 40 in the upper partition plate 18, thus permitting fluid communication between each filtration module 30 and the upper chamber 22. Further, the lower connector 38 of each filtration module 30 is sealed relative to a respective through hole 42 in the lower partition plate 20, thus permitting fluid communication between the lower chamber 24 and each filtration module.

[0187] In use, fluid to be filtered (such as seawater) may be driven from the lower chamber 24 and into the filtration modules 30 via the respective lower connectors 38, through the filtration membranes in the modules 30, with filtered water exiting the filtration modules via the respective upper connectors 36 and into the upper chamber 22. Accordingly, a lower connector 38 may define an inlet 44 of each filtration module 30, and an upper connector 36 may define an outlet 46.

[0188] Each reducing connector 36, 38 includes a first cylindrical portion 36a, 38a, a second, smaller diameter cylindrical portion 36b, 38b, and a tapered portion 36c, 38c extending therebetween, thus providing a funnel type structure.

[0189] The first cylindrical portions 36a, 38a are secured and sealed to respective ends of the shroud 34.

[0190] The second cylindrical portion 36b of each upper connector 36 engages a lower face of the upper partition plate 18. In particular, the second cylindrical portion 36b of each upper connector 36 superposes a through hole 40 in the upper plate 18 and engages the plate 18 around the periphery of the through hole 40. An end face of the second cylindrical portion 36b of the upper connector 36 defines an annular groove 48 which accommodates a seal member, such as an o-ring, to provide sealing between the upper plate 18 and the connector 36.

[0191] Each filtration module 30 is connected to the upper plate 18 by respective quill bolts 50 which extend through the through holes 40 from the upper chamber side 22 and threadedly engage the second cylindrical portion 36b, such that tightening of the quill bolts 50 presses the second cylindrical portion 36b of each connector 36 against the upper plate 18. Each quill bolt 50 defines a central bore 52 to retain fluid communication between the modules 30 and the upper chamber 22.

[0192] The second cylindrical portion 38b of each lower connector 38 is received within a through hole 42 in the lower partition plate 20. An outer surface of each second cylindrical portion 38b defines an annular groove 54 which accommodates a seal member, such as an o-ring, to provide sealing between the hole 42 in the lower plate 20 and the connector 38. The second cylindrical portion 38b of the lower connector is simply pushed into a respective through hole 42 in the lower partition plate 20, thus providing a simple structure with relative ease of manufacture. Furthermore, this arrangement permits relative movement between the filtration modules 30 and the lower plate 20 to be achieved, which may accommodate any deflections or the like within the apparatus 10 caused by effects of, for example, pressure, temperature and the like.

[0193] It should be noted that the reducing connectors 36, 38 permit the size of the through holes in the partition plates 18, 20 to be minimised without requiring a reduction in the outer dimensions, and thus capacity, of the body portion 32 of the modules. In this way the strength of the partition plates may be preserved, permitting thinner plates to be utilised, thus providing cost and weight savings.

[0194] A tubular member 56 extends through and from each through hole 42 in the lower plate 20 and into the lower chamber 24. Each tubular member 56 facilitates communication of a fluid from the lower chamber 24 into respective filtration modules 30. As will be described in further detail below, each tubular member 56 also facilitates distribution of a gas, such as a cleaning gas, into the filtration modules 30.

[0195] The shroud 34 of each filtration module 30 includes an array of ports 58 located at the upper end thereof adjacent the upper connectors 36 to provide fluid communication between the filtration modules and the intermediate chamber 26. In particular, the ports 58 permit fluid communication between a retentate side of filtration membranes within the modules 30 and the intermediate chamber 26.

[0196] The vessel 12 includes a number of ports to facilitate fluid communication to and/or from the vessel 12. As will be described in further detail below, individual ports may have multiple purposes depending on the operational mode of the apparatus 10, such as a filtering mode, cleaning mode or the like. For example, in some operational modes certain ports may define fluid inlets providing fluid communication into the vessel 12, whereas in other operational modes the same ports may define fluid outlets providing fluid communication from the vessel 12.

[0197] In the present embodiment the vessel 12 defines a port 60 for permitting fluid communication to and/or from the lower chamber 24. As will be described in further detail below, the port 60 may permit a fluid to be treated, such as seawater, to be communicated into the lower chamber 24. Further, the port 60 may permit a cleaning fluid, such as a chemical, a gas or the like, to be communicated into the lower chamber 24.

[0198] The vessel 12 further defines a port 62 for permitting fluid communication to and/or from the upper chamber 22. As will also be described in detail below, the port 62 may permit a filtered fluid to be drawn from the upper chamber 22 of the vessel 12, and to permit a cleaning fluid such as previously filtered fluid, a chemical, a gas or the like, to be communicated into the upper chamber 22.

[0199] The vessel 12 further defines a port 64 for permitting fluid communication to and/or from the intermediate chamber 26. In one embodiment the port 64 may be for use in permitting fluid to drain from the intermediate chamber 26. In the embodiment illustrated in FIG. 1, the port 64 is established by a tubular structure 66 which extends from an aperture 68 in the lower partition plate 20, through the lower chamber 24 and through the wall of the lower cap portion 12c of the vessel 12. Such an arrangement may permit complete draining of the intermediate chamber 26 when the apparatus is vertically orientated, as illustrated. However, in other embodiments the port 64 may be established to extend through a wall of the central cylindrical section 12a of the vessel 12.

[0200] The vessel 12 also defines a further port 70 for permitting fluid communication to and/or from the intermediate chamber 26. In one embodiment the port 70 may permit control of pressure within the intermediate chamber 26, and may define a vent, for example. The port 70 is established by a tubular structure 72 which extends from an aperture 74 in the upper partition plate 18, through the upper chamber 22 and through the wall of the upper cap portion 12b of the vessel 12. However, in other embodiments the port 70 may be established to extend through a wall of the central cylindrical section 12a of the vessel 12.

[0201] The various ports 60, 62, 64, 70 may permit the vessel 12 to be appropriately connected to pipe-work to define a complete filtration system, as illustrated in FIG. 4, reference to which is additionally made. In this respect, the capacity of the system may be increased by creating a parallel arrangement of the various apparatus located between broken lines 100.

[0202] Various operational modes of the filtration apparatus 10 will now be described. It should be recognised that the various features and structure of the apparatus 10 can permit many variations of operation to be undertaken, and as such the examples below are not exhaustive, but are simply provided for illustration only. Furthermore, the apparatus 10 may be utilised to treat many different fluids. However, in the examples below the apparatus 10 is utilised to treat water, such as seawater. Such treatment may permit a product water to be provided from the apparatus, or may function as one treatment stage in a larger treatment process. For example, the apparatus 10 may function to pre-treat seawater prior to a further treatment, such as a desalination treatment.

Commissioning

[0203] To commission and fill the vessel 12 in preparation for filtration, ports 62 and 64 are closed via respective valves 76 and 78, port 70 is opened via valve 80 to vent the intermediate chamber 26 to atmosphere, and valve 82 is opened to communicate raw water to the vessel 12 via port 60. Although not illustrated, the raw water may be pumped through port 60.

[0204] Accordingly, raw water may enter the lower chamber 24 and subsequently flow into the filtration modules 30 via the individual tubular members 56. The raw water may then pass upwardly within the shroud 34 of each module 30 and exit into the intermediate chamber 26 via the array of ports 58 at the top end of each shroud 34, thus permitting the intermediate chamber 26 to become filled, with air in said chamber 26 being displaced via the port 70. Complete filling of the intermediate chamber 26 may be recognised when water begins to flow through vent port 70, at which stage valve 80 may be actuated to close said port 70, such that the pressure within the vessel 12 may be increased to the desired operational pressure which will permit water to pass through the membranes in the modules 30.

Filtration

[0205] When filtration of the raw water is to be performed valve 82 remains open and valve 76 is actuated to open, such that water may be driven through the membranes in the modules 30, with filtered water exiting the modules 30 into the upper chamber 22. The filtered water may then exit the vessel 12 via port 62.

Cleaning

[0206] During use the membranes within the modules 30 will become fouled and blocked with particulate and other matter, such that the pressure drop across the modules will increase over time, reducing the efficiency of the apparatus 10. This may be addressed by various cleaning operations. In this respect it should be noted that the disclosed exemplary embodiment of the present invention permits multiple types of cleaning procedures to be utilised, providing significant advantages over prior art systems. Some examples of cleaning operation are provided below, and it should be understood that these are only exemplary and that various other operations or combination of operations may also be possible.

Cleaning Example 1Backwashinq

[0207] Valve 82 is closed to prevent further flow of raw water through port 60, and to maintain the lower chamber 24 filled with water. Valve 80 is opened to permit the vessel to be depressurised by venting via port 70, and valve 78 is also opened to permit fluid within the intermediate chamber 26 to drain therefrom. Valve 76 remains open and filtered fluid is reverse flowed, for example by being pumped, into the upper chamber 22 via port 62 and into and through the filtration modules 30, thus backwashing the membranes contained therein. The backwashed fluid which will carry the matter dislodged from the membranes then exits the modules 30 via ports 58 and into the intermediate chamber 26 and subsequently drained via port 64.

[0208] The presence of the fluid within the lower chamber 24 prevents the backwashed fluid from entering said chamber. Accordingly, the present embodiment permits the lower and intermediate chambers 24, 26 to be isolated from each other during backwashing thus eliminating the requirement to drain and re-fill the third chamber and therefore minimising the time that the apparatus 10 must be held off-line to perform this type of cleaning.

Cleaning Example 2Backwashinq

[0209] As a variation to Example 1 above, valve 78 may be closed to retain fluid within the intermediate chamber 26, and valve 84 may be opened. Accordingly, backwashed fluid from the upper chamber 22 may be washed through the modules 30 and exit into the lower chamber 24 to be drained via port 60. The presence of the fluid within the intermediate chamber 26 prevents the backwashed fluid from entering said chamber, and as such the intermediate chamber 26 may not need to be drained and re-filled, minimising down-time of the apparatus 10 for cleaning.

Cleaning Example 3Forwardwashing

[0210] In certain circumstances cleaning of the membranes may be achieved by forward flow of a washing fluid through the modules. In one configuration the forward washing fluid may pass through the membranes in a conventional filtering direction.

[0211] In another configuration the forward washing fluid may be cross-flowed over the surface of the membranes thus dislodging particulate and other material. That is, fluid may be passed over the surface of the membranes without, or with a minimal volume, passing through the membranes. The exemplary embodiment disclosed permits such cross-flow forwardwashing by virtue of the lower and intermediate chambers 24, 26 being isolated from each other.

[0212] To achieve forwardwashing valve 82 may be opened to permit raw water to flow into the third chamber via port 60, into the modules 30 and across the surfaces of the membranes, with the forwardwashed water containing dislodged material exiting into the intermediate chamber 26 via shroud ports 58. Valve 78 may be held open to permit the forward flowing water to be continuously drained from the intermediate chamber 26. As fluid is continuously drained from the intermediate chamber 26 pressure may not be permitted to be raised above that required to drive the fluid through the membranes.

[0213] All other valves and ports may be configured as necessary. For example valve 80 may be opened to also assist to avoid pressure developing in the intermediate chamber 26.

[0214] As a variation in this example the forward washing water may be provided by previously filtered water or permeate which is appropriately delivered or diverted into the lower chamber 24, for example via the port 60 and appropriate valves and piping.

Cleaning Example 4Simultaneous Backwashinq and Forwardwashing

[0215] The filtration apparatus in the disclosed exemplary embodiment may also support both forwardwashing and backwashing to be achieved simultaneously. Such may be achieved by opening valve 76 to permit permeate to be backwashed through the modules, opening valve 82 to permit raw water to be forwardwashed through the modules and across the membrane surfaces, and opening valve 78 to permit dirty forwardwashed and backwashed water to be drained from the intermediate chamber 26. All other valves may be configured appropriately.

[0216] As a variation, forwardwashing fluid may be provided by permeate which is diverted through port 60 via an appropriate valve arrangement.

Cleaning Example 5Chemically Enhanced Washing

[0217] In certain circumstances it may be desired to expose the membranes to a chemical to facilitate cleaning, for example to dissolve particulate matter, destroy bacterial growth and the like.

[0218] In one example a Chemically Enhanced Backwashing (CEB) may be utilised. Such CEB may be achieved in one example by opening valve 83 to permit a chemical, such as hypochlorite, to be dosed into backwashing permeate water and delivered into the vessel via port 62, with all other ports and valves configured appropriately for backwashing, as defined in Example 1 (or Example 2) above.

[0219] Furthermore, as the embodiment disclosed herein also permits forwardwashing to be achieved, as defined in Example 3 above, it is also possible in a variation to enhance such forward washing by dosing a chemical, such as hypochlorite into the raw water, or permeate, which is delivered into the vessel via port 60, with an appropriate piping and valve arrangement. Of course, simultaneous forward and backwashing may be achieved, as in Example 4 above, with chemical enhancement.

[0220] In certain embodiments it may be desired to allow the modules 30 to soak in the chemical which is introduced into the vessel 12.

[0221] A conventional backwash or forward wash may be performed before and/or after a chemically enhanced cleaning process.

Cleaning Example 6Cleaning-In-Place

[0222] The exemplary embodiment of the present invention may support a cleaning process known as Cleaning In Place (CIP), which may be utilised in circumstances where backwashing may not be sufficient, or where a more thorough cleaning is required, for example. In such an arrangement a CIP fluid, which may include a warmed fluid, a chemical or the like, may be delivered into the vessel via valve 84 and port 60, with the fluid appropriately flowing through the modules 30 and into the intermediate chamber 26. The CIP fluid may be retained within the vessel for a required period of time to allow the various components, and in particular the modules 30, to soak in the fluid.

[0223] The CIP fluid may be drained from the lower chamber 24 and from within the modules 30 via port 60 and valve 84. Further, the CIP fluid may be drained from the intermediate chamber 26 via port 64, and valve 78, and be routed to an appropriate drain by use of valves 86 and 88.

Cleaning Example 7Gas Scouring

[0224] The filtration apparatus 10 in the disclosed exemplary embodiment may support cleaning of the membranes by use of gas bubbles which function to scour the surfaces of the membranes.

[0225] In one example filtration may be ceased by closing valve 82, which will have the effect of retaining fluid within the lower chamber 24. The vessel 12 may be depressurised via valve 80 and port 70 and valve 78 may be opened to permit the intermediate chamber 26 to drain through port 64. Although the intermediate chamber 26 may be drained it should be noted that the modules 30 and tubular members 56 will remain filled with water by virtue of the shroud ports 58 being located at the upper ends of the modules 30.

[0226] A gas, such as air, may be delivered into the lower chamber 24 via valve 90 and port 60, passing upwardly through the liquid to form a gas space 106. In this respect, the fluid retained within the lower chamber 24 defines a liquid level 102, as illustrated in FIG. 1, which is located above lower open ends 104 of each tubular member 56, such that each tubular member 56 dips into the liquid in the lower chamber 24.

[0227] Each tubular member 56 also defines a port 108 (FIGS. 1 and 3b) in an outer surface thereof to facilitate communication of gas from the gas space 106 into the associated tubular member 56. Each port 108 is positioned at an elevated position above the liquid level 102 to permit inward flow of the gas by virtue of a pressure differential between the lower chamber 24 and the region of each tubular member 56 at the location of the port 108. This pressure differential is established by the difference in hydrostatic pressure between the liquid level in the tubular member 56 at the level of the port 108, and the liquid level 102 in the third chamber, wherein the pressure in the gas space 106 will be substantially equal to the pressure at said liquid level 102. Accordingly, the presence of this differential will facilitate relatively even distribution and inflow of gas into the tubular members 56.

[0228] The ports 108 and height differential between the ports 108 and liquid level 102 may be appropriately dimensioned to provide a desired flow rate of gas.

[0229] The gas which enters the tubular members 56 may then bubble upwardly through the fluid contained in the modules 30, with the bubbling action scouring and agitating the surface of the membranes to assist in dislodging particulate and other matter.

[0230] Such gas scouring cleaning may be achieved during backwashing and/or forwardwashing, and/or in combination with a chemically based cleaning operation, such as a chemically enhanced washing or a CIP operation.

[0231] Further, gas scouring may also be achieved by delivering gas into the vessel 12 initially via the upper chamber 22.

[0232] It should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto without departing from the scope of the invention. For example, the shroud component 34 of the modules may be optional in some embodiments. Furthermore, the reducing connectors may not be funnel shaped and may define a substantially constant diameter with appropriate sealing being provided to permit engagement with smaller diameter through holes in the partition plates. Also, it should be noted that although the illustrated embodiment orientates the apparatus vertically, other orientations are possible, such as horizontally or the like. Any number and size of filtration module may be provided. Also, in certain embodiments the apparatus may only include an upper partition plate and thus the vessel may only include two chambers. Further, in the illustrated embodiment a mechanical connection is achieved between the modules and the upper plate, whereas a compliant connection is provided between the modules and the lower plate. However, in an alternative embodiment the modules may be mechanically and substantially rigidly secured to the lower plate and compliantly secured or associated with the upper plate.