Abstract:
A method for reducing the amount of cleaned water required in cleaning a particulate strainer using a reverse flow system is disclosed herein. The method includes the steps of: disposing a stationary cylindrical strainer in a first fluid flow to capture particulates against a first upstream surface of the strainer; positioning a single self-contained ultrasonic energy source within an inner region of the stationary cylindrical strainer defined by a downstream second surface the second surface permitting passage of a cleaned fluid flow; stopping the first flow; activating the ultrasonic energy source to dislodge particulates from the first surface; sending a reverse flow of the cleaned fluid flow through the second surface and through the first surface to evacuate the dislodged particulates from returning to the first surface; and restoring the passage of the first flow through the strainer.

Description:
RELATED APPLICATIONS 
     This application is a divisional application of Ser. No. 09/873,526 filed on Jun. 4, 2001, entitled SELF-CLEANING WATER FILTER, which in turn is a Continuation-in-Part of application Ser. No. 09/737,411 filed on Dec. 15, 2000, now U.S. Pat No. 6,517,722 which is a Continuation-in-Part of application Ser. No. 09/417,404, filed on Oct. 13, 1999, now U.S. Pat. No. 6,177,022, which is a Continuation-in-Part of Co-Pending application Ser. No. 09/014,447 filed Jan. 28, 1998, now abandoned, the latter three of which are entitled SELF-CLEANING FUEL OIL STRAINER, and all of whose entire disclosures are incorporated by reference herein. 
    
    
     SPECIFICATION 
     BACKGROUND OF THE INVENTION 
     This invention relates generally to filter devices and, more particularly, to water system filters for small particulate contaminants. 
     It is well-known that the mechanical cleaning of a filter surface can be accomplished by having a brush or scraper drag along the filter surface where deposits have accumulated. In certain configurations, the brush or scraper is mounted at one end between two walls but with a significant portion of the brush or scraper projecting beyond the walls. Such configurations are shown in U.S. Pat. No. 148,557 (Gillespie et al.); U.S. Pat. No. 556,725 (Farwell); U.S. Pat. No. 740,574 (Kohlmeyer) and U.S. Pat. No. 793,720 (Godbe). In conventional filter systems, the particulate contaminants are driven off the filter surface and are deposited in a hopper or tank along with the fluid being filtered, thus discarding large amounts of the fluid being filtered. 
     The use of a brush, or high speed cleaning spray, disposed between a pair of walls for cleaning a cylindrical filter is known in the art, as is disclosed in U.S. Pat. No. 5,423,977 (Aoki et al.) and U.S. Pat. No. 5,595,655 (Steiner et al.) and Swiss Patent No. 22,863 (Zingg). Another variation employs a backwash that drives the particulate contaminants off of the cylindrical filter, as is disclosed in U.S. Pat. No. 3,338,416 (Barry). 
     An exemplary use of such filters is in a water desalination system that is available on ships. Shipboard water/salt water straining is a specialized straining process. In particular, the water/salt water flow is initially pre-strained for gross particulate contaminants, such that any particulate contaminants remaining in the water/salt water flow are extremely small (e.g., &lt;100 microns, with a large percentage being less than 25 microns). As a result, where these small particulate contaminants are captured by a downstream strainer (e.g., a wedge wire screen strainer), both on and within the strainer surface, and then later dislodged during the strainer cleaning process, these extremely small particulate contaminants do not fall by gravity toward a drain but remain suspended in the water/salt water and will re-attach to the strainer surface. Therefore, there remains a need for a cleaning device that can dislodge such extremely small particulate contaminants off of the downstream strainer surface, as well as from within the strainer surface, and then ensure that these particulate contaminants flow out through the drain rather than re-attaching to the strainer surface. 
     Thus, there is a need for an improved system for removing undesired particulate contaminants from a water/salt water flow and without interrupting that water/salt water flow to the engines, while minimizing the amount of fluid removed therewith. It is to just such a system that the present invention is directed. 
     SUMMARY OF THE INVENTION 
     A water cleaning system is disposed within a water flow having particulate contaminants therein. As mentioned earlier, the particulate contaminants that need to be removed from the water flow are extremely small, less than 100 microns, and a large percentage of these less than 25 microns, therefore do not settle out by gravity. The invention of the present application is well-suited to removing these small particulate contaminants from the water flow and into a drain. 
     In particular, a water filter is disposed within a water flow having particulate contaminants therein. The water filter comprises: a porous member in fluid communication with the water flow such that the water flow enters the porous member through a first porous member surface and exits through a second porous member surface and wherein the water flow deposits the particulate contaminants on the first porous member surface; particulate-removing means disposed to be in close proximity with the porous member for removing particulate contaminants from the first porous member surface along substantially the entirety of the length of the first porous member surface; a pair of flow confining walls are disposed to be in close proximity with the first porous member surface along substantially the entirety of the length of the first porous member surface for defining a chamber; a partition divides the chamber into a first subchamber and a second subchamber along the length of the chamber; a drive mechanism is provided for displacing the porous member for continuously directing particulate contaminants deposited on the first porous surface past the particulate removing means for continuously dislodging the particulate contaminants from the first porous member surface into the first subchamber; the partition includes first and second portions on opposite sides of the particulate removing means and each portion has a plurality of apertures for passing the dislodged particulate contaminants from the first subchamber into the second subchamber; and a drain is in communication with the second subchamber and through which the dislodged particulate contaminants are removed when the drain is opened. 
     A method is provided for cleaning a water flow having particulate contaminants therein. The method comprises the steps of: disposing a porous member in fluid communication with the water flow such that the water flow enters the porous member through a first porous member surface and exits through a second porous member surface so that the water flow deposits the particulate contaminants on the first porous member surface; positioning a pair of flow confining walls adjacent the first porous member surface to define a chamber and positioning a respective flexible member between a respective flow confining wall and the first porous surface member, and wherein the respective flexible members are in contact with the first porous surface; positioning a particulate-removing means closely-adjacent the porous member; dividing the chamber into first and second subchambers with a partition having first and second portions on opposite sides of the particulate removing means and each portion having a plurality of apertures to provide fluid communication between the first and second subchambers and wherein the second subchamber is in fluid communication with a drain when the drain is opened; displacing the porous member to permit the particulate-removing means to dislodge particulate contaminants trapped on the first porous member surface into the first subchamber; and opening the drain to cause the dislodged particulate contaminants to pass through the plurality of apertures into the second subchamber and out into the drain. 
     A water cleaning system is provided for use with a water flow having particulate contaminants therein. The cleaning system comprises: an inlet valve for controlling the water flow having particulate contaminants therein forming a contaminated water flow and wherein the contaminated water flow flows through a first output port of the inlet valve; a stationary porous member positioned in the contaminated water flow that passes through the first output port and wherein the contaminated water flow enters the stationary porous member through a first porous member surface and exits through a second porous member surface towards a second output port, and wherein the contaminated water flow deposits the particulate contaminants on the first porous member surface to form a clean water flow that flows toward the second output port; an outlet valve coupled to the second output port for controlling the clean water flow; a flow control means, operated during a porous member cleaning process, having a flow control means input coupled to a source of water and a flow control means output coupled to the second output port and wherein the flow control means controls a reverse flow of the clean water that flows from the second porous member surface through the first porous member surface for dislodging the particulate contaminants from the first porous member surface to form a contaminated reverse flow of water; a drain valve coupled to the first output port for directing the contaminated reverse flow of water towards a drain during the cleaning process; and the inlet valve and outlet valve are closed during the cleaning process. 
     A method is provided for cleaning a contaminated water flow having particulate contaminants therein. The method comprises the steps of: positioning a stationary porous member in the contaminated water flow such that the contaminated water flow enters the stationary porous member through a first porous member surface and exits through a second porous member surface toward an output port, and wherein the contaminated water flow deposits the particulate contaminants on the first porous member surface; isolating the stationary porous member from the contaminated water flow during a cleaning process; passing a reverse flow of clean water from the output port and through the stationary porous member from the second porous surface member surface to the first porous member surface for dislodging the particulate contaminants from the first porous member surface to form a contaminated reverse flow of water; opening a drain to receive the contaminated reverse flow of water; discontinuing the reverse flow of clean water While closing the drain to complete the cleaning process; and recoupling the stationary porous member to the contaminated water flow. 
     A water filter system for use with a water flow having particulate contaminants therein. The water filter system comprises: an inlet valve for controlling the water flow having particulate contaminants therein forming a contaminated water flow and wherein the contaminated water flows through a first output port of the inlet valve; a stationary porous member positioned in the contaminated water flow that passes through the first output port, and wherein the contaminated water flow enters the stationary porous member through a first porous member surface and exiting through a second porous member surface towards a second output port, and wherein the water flow deposits the particulate contaminants on the first porous member surface to form a clean water flow that flows towards the second output port; a third output port coupled to a drain through a drain valve; the inlet valve being closed while the drain valve is opened during a cleaning process for generating a reverse flow of the water that flows from the second output port towards the third output port, wherein the reverse flow of the clean water flows through the stationary porous member from the second porous member surface through the first porous member surface for dislodging the particulate contaminants from the first porous member surface to form a contaminated reverse flow of water that flows into the drain; and the drain valve being closed and the inlet valve being opened after the cleaning process is completed. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Many of the intended advantages of this invention will be readily appreciated when the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
     FIG. 1 is a block diagram of the water-desalination system in which the present invention is located; 
     FIG. 2 is a top view of the present invention; 
     FIG. 3 is a partial side view of the present invention; 
     FIG. 4 is a bottom view of the present invention; 
     FIG. 5 is a cross-sectional view of the present invention taken along line  5 — 5  of FIG. 2; 
     FIG. 6 is partial sectional view taken along line  6 — 6  of FIG. 5; 
     FIG. 7 is a partial sectional view taken along line  7 — 7  of FIG. 5; 
     FIG. 8 is a cross-sectional view of the present invention using a reverse flow of clean water/salt water as part of the particulate-removing means; 
     FIG. 9 is a partial sectional view taken along line  9 — 9  of FIG. 8; 
     FIG. 10 is similar to FIG. 9 except that a different reverse flow direction is depicted; 
     FIG. 11 is an enlarged, cross-sectional view of a portion of FIG. 5, depicting different portions of the partition and one of the associated wipers; 
     FIG. 12 is an enlarged, cross-sectional view of a portion of FIG. 5, depicting the passageways in the particulate-removing means support for use with the alternative drain configuration; 
     FIG. 13 is a partial isometric view of the internal particulate chamber depicting the partition and one of the wipers comprising the shoes; 
     FIG. 14 is a schematic of a water/salt water cleaning system using a stationary water/salt water strainer; 
     FIG. 15 is a variation of the water/salt water cleaning system of FIG. 14 wherein the downline water/salt water flow is used as the source of the reverse clean water/salt water flow; 
     FIG. 16 is another variation of the invention of FIG. 15; 
     FIG. 17 is a cross-sectional view of a stationary filter, that can be used in the systems shown in FIGS. 14-16, and having an ultrasonic generator disposed therein; 
     FIG. 18 is an enlarged view of the circled portion shown in FIG. 17; and 
     FIG. 19 is a sectional view of the stationary filter taken along line  19 — 19  of FIG.  17 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is a detailed description of the present invention. The present invention has wide application where straining very small particulate contaminants, less than 100 microns and large percentage of these are less than 25 microns, from a water/salt water flow is required, and is not limited to the environment shown in FIG. 1, as will be discussed in detail below. The present invention is characterized as a non-disposable cleaning device, i.e., having a porous member that can be cleaned rather than being thrown away. The term non-disposable is defined as an item that does not require periodic replacement, e.g., once a day, week or month. Thus, such a non-disposable item has obvious advantages in environments where storage is limited and cleaning device replenishment facilities are unavailable, e.g., ocean-going vessels. Other example systems include power plants, cogeneration facilities, etc. 
     As an exemplary environment, Applicants have depicted a water desalination system  1  for disclosing the preferred embodiment; such a water desalination system  1  may be used on watercraft, e.g., ships and boats. However, it should be understood that it is within the broadest scope of the present invention that it can be used in any water cleaning system and it is not limited to a water desalination system. 
     Referring now in greater detail to the various figures of the drawing, wherein like reference characters refer to like parts, there is shown in FIG. 1 at  520  a self-cleaning water filter of the present invention which forms a part of the system  1 . The water filter system  1  comprises five stages of straining/filtration followed by a reverse osmosis stage  6 . A pump  2  pumps sea water into a ⅛″ perforation self cleaning strainer  3  which discharges to a cyclone separator  4  (also referred to in the art as a “centrifugal separator”), which discharges to a 50 micron self cleaning wedge wire filter  5 . The wedge wire filter  5  discharges to the self-cleaning wire cloth (e.g., 10-20 micron) water filter  520  which, in turn, discharges to a 3 micron cartridge filter  6  and finally through the reverse osmosis membrane  7  to a fresh water user/storage stage  8 . 
     As shown more clearly in FIG. 2, the water filter  520  comprises two canisters  26  and  28  that are fed the main water flow with particulates, e.g., the sea water, from the wedge wire filter  5  via a common input manifold  30  (e.g., 2½ inch class 150 ANSI flanged input) at the top portion of the filter  520 . Each canister  26  and  28  has two inputs from the common manifold  30 , as indicated by inputs  32 A and  32 B for canister  26  and by inputs  34 A and  34 B for canister  28 . Each canister  26  and  28  comprises a cylindrical-shaped porous member  36  and  38 , respectively, through which the sea water flows, as will be discussed in detail later. The porous members  36  and  38  comprise a screen selected from the group consisting of wedge wire, wire cloth and perforated metal. In the preferred embodiment, the porous members  36  and  38  comprise wedge wire screens, such as those manufactured by Leem Filtration Products, Inc. of Mahwah, N.J. It is also within the broadest scope of the present invention that the porous members  36  and  38  may comprise wire cloth or perforated metal, as opposed to wedge wire screens. One of the main features of the water filter  520  is its ability to filter out fine particulate matter, e.g., particulates less than 100 microns, where a large percentage of these are less than 25 microns. 
     Drive mechanisms  40  and  42  (FIG. 3) are provided to rotate the respective porous members  36  and  38  during the cleaning process about their respective center axes, only one ( 44 ) of which is clearly shown in FIG.  5 . Otherwise, during normal operation, the porous members  36  and  38  remain stationary. 
     As can be seen in FIG. 2, sea water enters each canister through its respective inputs and then flows around the periphery of each porous member  36  and  38 ; in particular, sea water flow from inputs  32 A and  32 B are shown by arrows  46 A and  46 B, respectively, and sea water flow from inputs  34 A and  34 B are shown by arrows  48 A and  48 B, respectively. The inputs  32 A and  32 B are located on both sides of an internal particulate chamber  50  (FIG. 7, which comprises two dislodge subchambers  50 A/ 50 B and a drain subchamber  50 C, all of which are discussed later) in canister  26 ; similarly, although not shown, the inputs  34 A and  34 B in canister  28  are also located on both sides of a internal particulate chamber, also comprising two dislodge subchambers and a drain subchamber. Thus, water/salt water input flow moves away from the chamber  50  and around the periphery of the porous members  36  and  38  and then through them, as is discussed next. 
     Sea water flow through the porous member is more easily depicted in FIG. 5, which is a cross-sectional view of the canister  26 , although it should be understood that the following discussion is applicable to the other canister  28 . The main sea water flow is through the porous member  36 , from an outside surface  37  to an inside surface  39 , as indicated by the arrows  52 , and down through the hollow interior  41  of the porous member  36 . As the sea water then flows through the porous member  36 , particulate contaminants are then trapped against the outer surface  37  of the porous member  36 . The filtered sea water exits into a main output  54  of the canister, as shown by the arrow  56 . FIG. 4 is a bottom view of both canisters  26  and  28  and it shows the main output  54  of canister  26  and a main output  58  of canister  28  feeding into a common output manifold  60 . Thus, sea water flow through the filter  520  is basically continuous. 
     When cleaning of the porous member  36  and  38  is required, as indicated by pressure drop across the filter  520  (as measured by a pressure transducer, not shown), the drive mechanisms  40  and  42  are activated to rotate the respective porous members. In addition, solenoid valves  72  and  74  (FIG. 3) are activated to open respective drains (only one  76  of which is shown in FIG.  5 ), located directly below the drain subchamber  50 C, for diverting the particulate debris and a limited amount sea water down through a respective drain, rather than through the main outlets  54  and  58 . Furthermore, it is within the broadest scope of this invention to include other alternative locations for the drain, e.g., along the chamber, rather than under it, as will be discussed in detail later. Opening of the drain  76  (or the alternative drain) is kept to a minimum to discard as little sea water as possible while flushing the particulate contaminants from the chamber. Thus, for example, the drain  76  can be open all or any part of the time that the porous members  36  and  38  are rotating. 
     Cleaning of the porous members  36  and  38  is accomplished by the particulate-removing means, only one of which is shown most clearly in FIGS. 5,  7 ,  8  and  9 ; as such, the following discussion applies to the particulate-removal means in the canister  28  also. In the preferred embodiment, the particulate-removing means comprises an elongated wire brush  62  that spans the length of the porous member  36 . The brush fibers are in contact with the outside surface  37  of the porous screen  36  and thus bear on the outside surface  37  of the porous member  36  along its entire length. The brush  62  forms the separation between the two dislodge subchambers  50 A and  50 B, while the majority of a brush support  63  is disposed inside the drain subchamber  50 C, as shown in FIG.  7 . 
     As mentioned previously, the chamber  50  comprises the two dislodge subchambers  50 A/ 50 B and a drain subchamber  50 C. The chamber  50  comprises a pair of confining walls  64 A and  64 B, also running the length of the porous member  36 , that enclose the brush  62 /brush support  63 . The purpose of these walls  64 A and  64 B is to contain the dislodged particulate debris within the chamber  50  so that substantially only sea water within this chamber  50  will be discharged through the drain  76  (or alternative drain  300 , to be discussed later) during cleaning. A partition  200 , also running the length of the porous member  36 , forms the separation between the two dislodge subchambers  50 A/ 50 B and the drain subchamber  50 C. The partition  200  itself comprises a pair of outer flanges  202 A/ 202 B, a base wall  204  and sidewalls  206 A/ 206 B. The base wall  204  is secured between a particulate-removing means (e.g., brush  62  or scraper) head  61  and the particulate-removing means support  63 . At the bend between the sidewalls  206 A/ 206 B and the outer flanges  202 A/ 202 B, the partition  200  comprises a plurality of apertures  212  (FIGS. 7,  9 ,  11  and  12 ) that permit the passage of dislodged particulate contaminants from the two dislodge subchambers  50 A/ 50 B to the drain subchamber  50 C. Because of the size of the apertures  212  (e.g., 0.094″ diameter), once any particulate contaminants from the two dislodge subchambers  50 A/ 50 B make their way through the partition  200 , there is very little chance that such particulate contaminants can find their way back through the apertures  212  and ultimately return to the outer surface  37 . 
     A drain passageway  75 , through a strainer support housing  77 , is also shown in FIG.  5 . FIGS. 7 and 9 also show the passageway  75  in phantom. 
     At the extreme ends of the confining walls  64 A and  64 B, respective wipers  65 A and  65 B are secured to the outside surfaces of the walls  64 A and  64 B, respectively, and which also run the length of the porous member  36 . The wipers  65 A and  65 B (e.g., 316 stainless steel, half-hard) are coupled to the ends of the walls  64 A and  64 B using fasteners  78  and plates  79 . As can be seen most clearly in FIG. 13, wiper  65 A comprises a plurality of spaced-apart shoes or runners  67  that are in contact with the outer surface  37  of the porous member  36 . These shoes  67  (e.g., 0.010″-0.015″ thickness and ¼″ wide and which may be spot-welded to the wiper  65 A) serve to maintain the wiper  65 A a sufficient distance away from the outer surface  37  such that during cleaning, while the porous member  36  is rotating (direction of rotation is shown by the arrow  161  in FIG.  7 ), the particulate contaminants adhering to the outer surface  37  pass beneath the wiper  65 A between the shoes and then are driven off of the outer surface  37  by the particulate-removing means  62  and into the dislodge subchamber  50 A. The drain subchamber  50 C is in direct fluid communication with the drain  76  (or alternative drain  300 ). When the drain  76  (or alternative drain  300 ) is open, any particulate contaminants suspended in the dislodge subchamber  50 A are pulled toward the apertures  212  in the partition  200  and pass through them and out to the drain  76  (or  300 ). 
     Any remaining particulate contaminants which cannot be mechanically driven off of the surface  37  by the brush  62 , e.g., particulate contaminants lodged in between the outer surface  37  and the inside surface  39  of the porous member  36  (e.g., lodged in the wedge wire cells of a porous member  36  comprising wedge wire), are subjected to a reverse pressure and are driven out of the surface  37  into the second dislodge subchamber  50 B. In particular, unlike the first dislodge subchamber  50 A which is not totally closed off since the wiper  65 A stands off from the outside surface  37  of the porous member  36 , the second dislodge subchamber  50 B forms a completely-closed off chamber because the wiper  65 B does not include shoes and, therefore, is in contact with the outer surface  37  along its entire length. Thus, the second dislodge subchamber  50 B is subjected completely to the influence of the pressure differential created between the inside surface  39  of the porous member  36  and the opened drain pressure which is present in the drain subchamber  50 C, via the apertures  212 . When the drain  76  (or  300 ) is open, these particulate contaminants, lodged in between the outer surface  37  and the inside surface  39  of the porous member  36 , are driven out of that region by the reverse pressure differential and then are suspended in the second dislodge subchamber  50 B; this pressure differential also pulls these particulate contaminants toward the apertures  212  in the partition  200  and into the drain subchamber  50 C for passage through the drain  76  (or  300 ). 
     As pointed out earlier, the particulate contaminants are of an extremely small size, less than 100 microns, and a large percentage of these are less than 25 microns; as a result, these particulate contaminants do not settle out by gravity into the drain but rather, due to their small size, remain suspended in the sea water. The invention of the present application is well suited to overcome this problem as described below. 
     It should be understood that the apertures  212  provide for fluid communication between the first dislodge subchamber  50 A and the drain subchamber  50 C and for fluid communication between the second dislodge subchamber  50 B and the drain subchamber  50 C. However, because the apertures  212  are small, they maintain a high velocity of particulate contaminants from both the first and second dislodge subchambers  50 A and  50 B into the drain subchamber  50 C under the influence of the reverse pressure differential. Such a high velocity cannot be sustained by replacing the apertures  212  with a slot. Furthermore, replacing the apertures  212  with a slot would defeat the purpose of maintaining the transferred particulate contaminants (i.e., particulate contaminants that have passed from the dislodge subchambers  50 A/ 50 B) in the drain chamber  50 B since the particulate contaminants would not be precluded from making their way back to the outer surface  37  of the porous member  36 . 
     In particular, the advantage of using the plurality of apertures, as opposed to a slot of the type shown in U.S. Pat. No. 5,595,655 (Steiner et al.), is that the plurality of apertures provides for a rapid flow velocity as opposed to a low flow velocity for the slot. For example, if there are 21 apertures that form one set of apertures in the partition  200 , each having a diameter of approximately 0.094″, then the total area is approximately π(0.094″/2) 2 ×21=0.1457 in 2 . If, on the other hand, a slot having a width of 0.094″ and a length of 12.594″ (i.e., the length from the top of the uppermost aperture in the partition  200  to the bottom-most aperture in the partition  200 ; this is a reasonable assumption since the Steiner et al. patent states that the slot is substantially equal to the scraper length-Steiner et al. patent, col.  1 , lines  61 - 62 ) is used, the area is 1.184 in 2 . Thus, using a plurality of apertures presents only ⅛ the area of the slot. As a result, for a given flow rate (gallons/minute), the slot may provide flow velocity of 1 ft/sec whereas the apertured partition generates a flow velocity of 8 ft/sec. The higher velocity significantly reduces the chance that a particulate will migrate backwards through the plurality of apertures and reattach to the porous surface  36 . 
     It is also within the broadest scope of the present invention to include an alternative drain  300  configuration as shown most clearly in FIGS. 5,  8  and  12 . To that end, a drain  300  is depicted along side the drain subchamber  50 C rather than disposed underneath the subchamber  50 C, as discussed, previously. The drain  300  comprises drain passageways  302 ,  304  and  306  that form a portion of the particulate-removing means support  63 . The passageways  302 - 306  are coupled at one end to a common manifold  308  through which the dislodged particulate contaminants are disposed of. As shown in FIG. 12, the other end of each passageway  302 - 306  comprises a respective cross hole  310 ,  312 , and  314  disposed in the drain subchamber  50 B. Thus, when a drain solenoid valve  316  (FIG. 5) is activated as discussed previously, particulate matter that has been dislodged from the outer surface  37  of the porous members  36 / 38  into the two dislodge subchambers  50 A/ 50 B, passes through the apertures  212  in the partition  200  into the drain chamber  50 B. From there, the dislodged particulate contaminants are driven into the cross holes  310 - 314 , through the passageways  302 - 306  and then into the common manifold  308 . Thus, particulate contaminants dislodged from the outer surface  37  of the porous members  36 / 38  would be driven into the alternative drain  300 . 
     Alternatively, instead of using a single solenoid valve  316 , it is within the broadest scope of this invention to include dedicated solenoid valves  318 ,  320  and  322  (FIG. 5) that individually couple respective passageways  302 - 306  to the common manifold  308 . 
     It is also within the broadest scope of the present invention that the term particulate-removing means include a brush, a scraper, or any equivalent device that is used to dislodge particulate contaminants from the outside surface  37  of the porous members  36  and  38 . For example, where larger particulate contaminants are to be filtered from the water flow, a scraper (not shown) can be used in place of the brush  62 . 
     It is also within the broadest scope of the present invention that the particulate-removing means also encompasses a reverse flow of clean water for dislodging the particulate contaminants from the water filter  520 ; or a reverse flow of clean water in combination with the particulate-removing member (e.g., brush or scraper), discussed previously. 
     In particular, as shown in FIGS. 8-10, a second embodiment of the present invention comprises a particulate-removing means that includes an elongated spraying element  151  comprising a plurality of ports  153 . The elongated spraying element  151  is coupled to a pressure source  155  (e.g., a pump, air supply, etc.) that recirculates clean water (whose flow is indicated by the arrow  56 ) into the elongated spraying element  151 , during cleaning only, to create a high energy water spray that emanates from each of the ports  153 . As shown most clearly in FIG. 9, the direction of the high energy spray (indicated by the arrow  157 ) is from the inside surface  39  to the outside surface  37  of the porous member  136 . Thus, as the porous member  36  is rotated (direction indicated by the arrow  161 ) during cleaning, the high energy spray drives the particulate contaminants from the outside surface  39  into the dislodge subchamber  50 B. 
     It should be understood that the particulate-removing means may comprise the elongated spraying element  151  alone for driving off the particulate contaminants, or the particulate-removing means may comprise a particulate-removing member (e.g., a brush  62  or scraper) in addition to the elongated spraying element  151 , as shown in FIGS. 8-9. Together, the elongated spraying element  151  and the particulate-removing member (e.g., brush  62  or scraper) act to dislodge the particulate contaminants from the outside surface  37  of the porous member  36  during cleaning. When the particulate-removing member (e.g., a brush  62  or scraper) is used in combination with the elongated spraying element  151 , the direction of the high energy spray (indicated by the arrow  163 ) may be set to occur after the particulate-removing member dislodges some of the particulate contaminants (FIG.  10 ), thereby driving particulate contaminants into the second dislodge subchamber  50 B. 
     The porous member  36 , for use in this second embodiment, comprises an open lower end  137  (FIG. 8) to permit passage of the elongated spraying element  151  therethrough. 
     Another variation of the self-cleaning water filter that utilizes a reverse flow of clean water for cleaning purposes is depicted at  220  in FIG.  14 . In particular, as indicated by the arrow  165 , during normal operation, sea water enters through an inlet valve  167  to a water filter  220 . During normal operation, a drain valve  171  and a purge valve  173  remain closed, as will be discussed in detail later. The water filter  220  comprises a porous member  236 , preferably having a wire cloth configuration. The direction of the main sea water flow through the porous member  236  is given by the arrows  52  and is similar to the flow for the porous members discussed previously, i.e., from an outside surface  37  of the porous member  236  to an inside surface (not shown) of the porous member  236  and then through the center portion  41  of the porous member  236 . The cleaned sea water is then passed through an outlet valve  175  in the direction of the arrow  177 . 
     The cleaning process for the water filter  220  is different from the previous embodiments in that the porous member  236  does not move during cleaning. Instead, a reverse flow of clean water (the direction of this reverse flow is given by the arrow  179 ) is injected down through the center of the porous member  236 , from the inside surface to the outside surface  37  of the porous member  236 . This reverse flow of clean water impacts the entire inside surface of the porous member  236  and flows to the outside surface  37  of the porous member  236 , thereby dislodging the particulate contaminants from the outside surface  37  of the porous member  236 . Since this reverse flow acts through the entire porous member  236 , there are no confining walls used. Thus, in this embodiment, the particulate removal means comprises only the reverse flow of clean water. Because this reverse flow of clean water is applied through the entire porous member  236 , the water filter  220  must be isolated from the normal sea water flow during cleaning, as will be discussed in detail below. 
     In particular, when cleaning is required, the inlet valve  167  and outlet valve  175  are closed and the purge valve  173  and drain valve  171  are opened. The purge valve  173  is coupled to a clean water reservoir  181  which is under pressure (e.g., an air supply, whose input flow is indicated by the arrow  183  and having a valve  185  for maintaining air pressure in the reservoir  181 . The downstream clean water, indicated by the arrow  187 , enters the reservoir  181  through a recharge valve  189 ). When the purge valve  173  and the drain valve are opened, the reverse flow of clean water  179  drives the particulate contaminants off of the outside surface  37  of the porous member  236 ; this reverse flow, now containing the dislodged particulate contaminants, flows out, as indicated by the arrow  191 , through the drain valve  171 . Once this flow of dislodged particulate contaminants passes to the drain, the purge valve  173  and the drain valve  171  are closed and the input valve  167  and the output valve  175  are opened, restoring normal sea water flow. 
     It should be understood that the continuous sea water flow is accomplished by having a plurality (e.g., five to eight) parallel, non-rotating filter paths (not shown) that are coupled to the reservoir  181  through respective purge valves  173 . Thus, when any one non-rotation filter path is being cleaned using the reverse water flow, the remaining parallel channels are operating under the normal sea water flow. 
     Another variation of this embodiment, depicted in FIG. 15, uses the downstream clean water directly to create the reverse water flow. In particular, the purge valve  173  is coupled directly to the downstream clean water flow. The sequence of valve openings/closings are similar to that described previously. Thus, when the purge valve  173  and the drain valve  171  are opened a pressure differential is created and the reverse flow of clean water, the direction indicated by the arrow  179 , is generated directly from the downstream clean water flow. 
     Another variation of this embodiment is shown in FIG. 16 that uses passive components such as a check valve  400  and a flow restricting orifice  402  in place of the purge valve  173 . 
     It should also be understood that the variations of FIGS. 15 and 16, like that discussed with regard to FIG. 14, also comprise a plurality of parallel, non-rotating filter paths that permit the continuous flow of sea water when any one of the parallel, non-rotating filter paths is being cleaned by the reverse flow of clean water. 
     FIGS. 17-19 depict an exemplary stationary filter  220 ′, having an ultrasonic generator  300  disposed therein, that can be used in the systems shown in FIGS. 14-16 and, more preferably, to the systems of FIGS. 15-16. 
     Before proceeding with a discussion of FIGS. 17-19, it should be understood that in FIGS. 14-16, the input flow  165  is shown in an upward direction from the bottom of the page toward the outlet flow  177  shown at the top of the page, for clarity only. The actual flow of any of the systems shown in FIGS. 14-16 is exemplary only and may be in any number of directions and, therefore, is not limited to those depicted in those figures. Thus, the orientation of the stationary filter  220 ′ shown in FIGS. 17-19 is simply inverted from that shown in FIGS. 14-16. Thus, the “top surface”  221 ′ in FIG. 17 corresponds to the “bottom” surface  221  shown in FIGS. 14-16. 
     As will also be discussed in detail later, the input line into the stationary filter  220 ′ is from the side of the canister  26 ′, at an input port  32 ′, rather than from the “bottom” surface  221  shown in FIGS. 14-16; the reason for this will also be discussed later. In addition, a dedicated drain port  376  passes the dislodged particulate contaminants away from the stationary filter  220 ′ to a drain (not shown). Because of these port configurations, the input tee  291  in the systems of FIGS. 14-16 is eliminated. 
     As shown in FIG. 17, the stationary filter  220 ′ is housed in the canister  26 ′. On one side of the canister  26 ′ is the input port  32 ′ while on the other side of the canister  26 ′ is the drain port  376 ; at the bottom of the canister  26 ′ is an output port  54 ′. The ultrasonic generator  300  is disposed inside the hollow interior  41  of the stationary filter  220 ′. The inlet valve  167  is coupled to the port  32 ′ and the drain valve  171 ′ is coupled to the drain port  376 . The valves  167 / 171 ′ and the ultrasonic generator  300  are operated by a controller (not shown) during the cleaning process of the stationary filter  220 ′ itself, as will be discussed later. 
     As shown most clearly in FIG. 19, the stationary filter  220 ′ is positioned inside a chamber formed by a circular wall  380 . The wall  380  comprises a plurality of sets (e.g., eight) of vertically-aligned holes (e.g., ¼″ diameter) dispersed around the circular wall  380  (see FIG.  17 ); one hole  382  of each of the plurality of vertically-aligned holes is shown in FIG.  19 . As will be discussed in detail later, the circular wall  380  acts to minimize the effects of the high velocity particulate-contaminated input flow  165 , as well as to deflect and disperse the flow  165  all around the stationary filter  220 ′. 
     The stationary filter  220 ′ comprises three parts: (1) an outer wire cloth layer  384  (e.g., 5 microns); (2) an inner 40-50 mesh layer  386 ; and (3) an inner perforated metal enclosure  388  (e.g., 16-18 gauge, stainless steel) all of which are microwelded together. The perforated metal enclosure  388  comprises staggered holes  390  (e.g., ¼ diameter, see FIG. 17) that results in an overall surface area that is approximately 50-60% open. The outer wire cloth layer  384  filters out the particulate contaminants of incoming water/salt water flow that passes through the holes  382  in the circular wall  380 ; in particular, as the incoming water/salt water flow  165  passes through an outer surface  385 ′ (see FIG. 18) of the wire cloth layer  384  to an inner surface  385 ″ of the wire cloth layer  384 , the particulate contaminants lodge against the outer surface  385 ′. The 40-50 mesh layer  386  disperses the cleaned input flow around the periphery of the perforated metal enclosure  388  and through all of the holes  390  therein. The cleaned water/salt water flow then flows downward through the hollow interior  41  of the stationary filter  220 ′ and through the output port  54 ′. 
     Although not shown, another version of the stationary filter  220 ′ comprises only two parts: (1) an outer wire cloth layer (e.g., 5-20 microns) directly over a wedge wire inner layer with {fraction (5/16)} inch slot openings between the turns of wedge wire. Advantages of this second version of the stationary filter  220 ′ are that it allows a 90% open area as well as more direct contact with the backwash flow and the ultrasonic waves. 
     As can also be seen most clearly in FIG. 19, several continuous support members  392  are disposed between the outer wire cloth layer  384  of the stationary filter  220 ′ and the circular wall  380 . These continuous support members  392  form independent sectors  394  (e.g., eight, FIG. 19) around the periphery of the wire cloth layer  384 . As mentioned earlier, during normal sea water flow, the effects of the high velocity particulate-contaminated input flow  165  are minimized by the presence of the circular wall  380  and the sectorization formed by the continuous support members  394 ; these sectors  394  segment the input flow  165  so that the input flow  165  impacts the wire cloth layer  384  around the entire stationary filter  220 ′. In particular, once the particulate-contaminated input flow  165  in each sector  394  passes through the vertically-aligned apertures  382 , the input flow  165  encounters the outer surface  385 ′ of the wire cloth layer  384  which traps the particulate contaminants therein. As also mentioned earlier, the cleaned water then passes through the 40-50 mesh layer  386  which disperses the cleaned input flow around the periphery of the perforated metal enclosure  388  and through all of the holes  390  therein. The cleaned water flow then flows downward through the hollow interior  41  of the stationary filter  220 ′ and through the output port  54 ′ 
     The stationary filter  220 ′ is releasably secured inside the canister  26 ′ using four tie bars  396  (FIG. 19) that couple between a lower baseplate  398  and an upper securement surface  400 . To properly seal the stationary filter  220 ′ inside the canister  26 ′ an upper annular seal  402  (e.g., rubber, see FIG. 18) and a lower annular seal  404  (e.g., rubber) are used. 
     The ultrasonic generator  300  (e.g., the Tube Resonator RS-36-30-X, 35 kHz manufactured by Telsonic USA of Bridegport, N.J.) is releasably mounted in the hollow interior  41  of the stationary filter  220 ′. In particular, an elongated housing  393  of the ultrasonic generator  300  is suspended in the hollow interior  41  of the stationary filter  220 ′. Thus, when the reverse flow of clean water/salt water  179  occupies the hollow interior  41 , the ultrasonic generator  300  is energized wherein the ultrasonic energy is applied to the wire cloth layer  384  in the direction shown by the arrows  395  through the holes  390 . The elongated housing  393  is attached to an electrical connector  397  which forms the upper portion of the ultrasonic generator  300 . The electrical connector  397  is then releasably secured to the canister  26 ′ (e.g., a nut  399 ). A wire harness  401  provides the electrical connection to the ultrasonic generator  300  from the controller (not shown). In this configuration, it can be appreciated by one skilled in the art, that the ultrasonic generator  300  and stationary filter  220 ′ can be installed/replaced rather easily without the need to disconnect any plumbing from the input port  32 ′, output port  54 ′ or drain port  376 . 
     During normal operation, the inlet valve  167  is open and the drain valve  171 ′ is closed, thereby allowing the contaminated water/salt water flow  165  to be cleaned by the stationary filter  220 ′ as discussed above. When the stationary filter  220 ′ itself is to be cleaned, the controller (not shown) closes the inlet valve  167  while opening the drain valve  171 ′. As a result, a high pressure reverse flow  179  of clean water flows from the output port  54 ′ and through the three-part stationary filter  220 ′ and out through the drain port  376 . As this reverse flow  179  passes through the wire cloth layer  384 , the particulate contaminants are dislodged from the outer surface  385 ″ of the wire cloth layer  384  and then driven out through the drain port  376 . It should be noted that during this high pressure reverse flow  179 , the continuous support members  392  also act to prevent the wire cloth layer  384  from separating from under laying support. The reverse flow  179  is applied for a short duration (e.g., approximately 4-5 seconds). 
     At the end of this application, and while there is still clean water in the hollow interior  41  but where the flow  179  is simply migrating (e.g., movement of clean water in inches/minute) rather than flowing, the controller (not shown) activates the ultrasonic generator  300  for a longer duration (e.g., 30 seconds to a couple of minutes) to provide for further cleaning of the wire cloth layer  384  by using ultrasonic energy to dislodge any remaining particulate contaminants in the wire cloth layer  384  into the migrating water flow and out through the drain port  376 . 
     Without further elaboration, the foregoing will so fully illustrate our invention and others may, by applying current or future knowledge, readily adapt the same for use under various conditions of service.