Rotary disc filter having a backwash system that includes a compact nozzle support structure

A rotary disc filter having a backwash system that includes a series of feed pipes that project into and between successive filter discs that are mounted on a rotatable drum. Connected to an outer terminal end portion of the feed pipes is a series of nozzle holders. Each nozzle holder includes a main conduit, a series of branch conduits that project outwardly from the main conduit, and a connector for connecting the nozzle holder to a respective feed pipe. A series of detachable nozzles are secured to the outer terminal ends of the branch conduits.

FIELD OF THE INVENTION

The present invention relates to rotary disc filters, and more particularly to rotary disc filters and their backwashing systems.

BACKGROUND OF THE INVENTION

A rotary disc filter employs a backwash system that is periodically actuated to backwash the filter media and dislodges suspended solids disposed on the inner sides of the filter media. Such backwashing systems employ nozzle support assemblies for supporting nozzles adjacent the filter media. There are a number of disadvantages and drawbacks to conventional nozzle support assemblies. First, in a typical rotary disc filter design, there is provided a backwash manifold that extends along one side of the disc filter. Inner steel pipes connected to the manifold extend into areas between the filter discs. Conventional nozzles and associated nozzle support assemblies are operatively connected to the inner end portions of the inner steel pipes. The inner steel pipes and the associated nozzle support assemblies are quite heavy and place a significant torque on the manifold. Secondly, these nozzle support assemblies typically include multiple parts. The steel pipes have to be drilled to provide openings to emit backwash. Typically, these nozzle support assemblies include welded and screw joints that have the potential to leak. In the end, such conventional nozzle support assemblies are costly and require a significant amount of assembly time.

Therefore, there has been and continues to be a need for a nozzle support assembly design that reduces cost, assembly time, number of parts, joints, seals and reduces potential leakage points.

SUMMARY OF THE INVENTION

The present invention relates to a rotary disc filter having a filter backwash system that includes a nozzle holder configured to support multiple nozzles and configured to be operatively connected to a backwash feed pipe, sometimes referred to as an inner pipe.

In one embodiment, the nozzle holder includes an elongated main conduit having an outer wall and a series of branch conduits projecting outwardly from the outer wall and including terminal end portions. Nozzles are detachably secured to the terminal end portions of the branch conduits.

Further in one embodiment, the nozzle holder is constructed of molded plastic and includes a main conduit having an outer wall and a plurality of branch conduits that project outwardly from the outer wall. The branch conduits include terminal end portions that receive detachable nozzles. In this embodiment, the nozzle holder including the main conduit, outer wall, and branch conduits are all formed into a single piece of molded plastic.

DESCRIPTION OF EXEMPLARY EMBODIMENT

With reference to the drawings, there is shown therein a rotary disc filter indicated generally by the numeral10. As discussed below, disc filter10includes a unique nozzle support structure that forms a part of a backwashing system. Before discussing design features of the backwash system, it may be beneficial to briefly discuss the basic design of rotary disc filters.

With particular reference to the drawings (FIGS. 1, 1A and 2), disc filter10comprises an outer housing12. Housing12typically includes a top, bottom, sides and ends. It should be noted that some rotary disc filters (a second type) are not provided with a substantial housing structure. These disc filters are often referred to as frame-type disc filters as they are designed to be installed in a pre-formed concrete basin. There is a third type or version of a disc filter which includes a half tank or frame with a bottom and sides and which only reaches to about the center of the drum of the disc filter.

In any event, either type of disc filter is provided with a frame structure for supporting various components that make up the disc filter10. In this regard, a drum14is rotatively mounted in the frame structure of the disc filter. Generally, the drum14is closed except that it includes an inlet opening and a series of openings14A formed in the surface thereof that enable influent water to flow from the drum into a series of disc-shaped filter members (sometimes referred to as filter discs) indicated generally by the numeral16and which are mounted on the drum. SeeFIG. 1A. That is, as will be appreciated from subsequent discussions herein, influent water to be filtered is directed into the drum14and from the drum through openings therein into the respective disc-shaped filter members16.

The number of filter discs16secured on the drum14can vary. Each filter disc16includes a filter frame18and filter media20secured or disposed on opposite sides thereof. A water holding area is defined inside each filter disc16for receiving and holding water to be filtered by the disc filter10. Head pressure associated with the influent water is effective to cause the water to flow outwardly from the filter disc16and through the filter media20. Water exiting the filter disc16is filtered water or filtrate. This results in suspended solids in the water being captured on the interior surfaces of the filter media20. As described below, a backwashing system is employed from time-to-time to dislodge the suspended solids from the filter media20where the suspended solids fall into a trough disposed in the drum after which the suspended solids and some backwash is discharged from the disc filter10via a sludge outlet21. SeeFIG. 1A.

Filtered water exiting the filter disc16is collected in a filtered water holding chamber or area that underlies the filter disc. The filtered water holding chamber or area includes an outlet that enables the filtered water to be discharged from the disc filter10.

As people ordinarily skilled in the art appreciate, during the backwashing operation it is necessary for the drum14and the filter discs16mounted thereon to rotate. Disc filter10is provided with a drive system for rotating the drum14and the filter disc16mounted thereon. In the case of the embodiment illustrated inFIG. 2, mounted to a panel or a wall structure about the back portion of the disc filter10is a drum motor30that is operative to drive a sprocket or sheave13that is connected to a shaft on which the drum14is mounted (FIG. 2). Various means can be operatively interconnected between the drum motor30and the sprocket or sheave13for rotating the drum14. In one example, a chain drive is utilized to drive a sprocket secured to a shaft that rotates the drum14. Various other types of drive systems can be utilized to rotate the drum and the filter disc16. In some cases, for example, there may be a direct drive on the drum shaft from a geared motor.

FIG. 1Ais a perspective view of the disc filter10with portions broken away to better illustrate the internal structure of the disc filter and the flow of influent into the disc filter and the flow of filtrate (effluent) from the disc filter. In the case of the embodiment illustrated inFIG. 1A, disc filter10is provided with an influent inlet22. Influent inlet22leads to an influent holding tank24. The influent holding tank24is optional. That is, it is not required in some disc filter designs. Influent holding tank24is disposed adjacent an inlet opening of the drum14such that influent held within the holding tank24flows from the holding tank into the drum14. As seen inFIG. 1A, the influent holding tank24is disposed on the upstream side of the disc filter10. Disposed around and generally below the influent holding tank is a bypass tank28. An outlet32enables influent to flow from the bypass tank28. Note that the influent holding tank24includes overflow openings. These overflow openings permit influent overflow to flow from the holding tank24downwardly into the bypass tank28. This effectively limits the water level height in the influent holding tank24. There is an alternative design for the separate bypass tank28. This is referred to as a “mixing bypass”. This design simply entails mixing the unfiltered bypass water with the filtered water in the filtrate tank and directing the mixture from the disc filter usually from a rear portion of the disc filter.

Disc filter10includes a filtrate or effluent holding tank26. In the case of the embodiment illustrated inFIG. 1A, the effluent holding tank26is disposed about a downstream end portion of the disc filter10. As shown inFIG. 1, the effluent holding tank26extends around at least a lower portion of the filter disc16. As the influent moves outwardly through the filter media20, this results in the water being filtered, and it follows that the filtered water constitutes a filtered effluent. It is this effluent that is held in the effluent holding tank26. An outlet (not shown) can be conveniently located at various places for discharging the filtered effluent from the effluent holding tank26.

The above discussion provides a general overview of rotary disc filters. For a more complete and unified understanding of rotary disc filters, their structure and operation, one is referred to U.S. Pat. Nos. 7,972,508 and U.S. patent application Ser. No. 14/775,196, the disclosures of which are expressly incorporated herein by reference.

Rotary disc filter10includes a backwashing system for periodically backwashing the filter media20. The backwashing system comprises a backwash pump50, a manifold52that extends along a side portion of the disc filter10, and a series of feed pipes54connected to the manifold52and projecting inwardly therefrom. Feed pipes54, sometimes referred to as inner pipes, project from the manifold52into areas between the filter discs16. Secured to the feed pipes54are a series of nozzle holders indicated generally by the numeral56. Nozzle holders56are designed to receive detachable nozzles58. As will be appreciated from subsequent portions of the disclosure, backwash pump50pumps a backwash from a backwash source, such as the filtered water, into and through the manifold52. Backwash pump50is operative to pump the backwash from the manifold52into the respective feed pipes54and from the feed pipes into and through the nozzle holders56and out the respective nozzles58. In some embodiments, the disc filter itself may not include a backwash pump50. In other embodiments, pressurized backwash can be provided from a source other than a backwash pump that forms a part of the rotary disc filter.

Manifold52can be rigidly mounted or rotatively mounted along one side of the disc filter10. In some cases, manifold52is operatively connected to a drive (not shown) that can be indirectly driven off the drum motor30or the drum14. In any event, the manifold52during a cleaning operation can oscillate back and forth, which results in nozzles58sweeping back and forth between the filter media20so as to backwash particular areas of the filter media20. In other cases, the manifold52, as noted above, is rigidly mounted and does not oscillate back and forth during the backwashing operation.

Each feed pipe54is configured to communicatively connect to one or a plurality of nozzle holders56. SeeFIG. 5. Note that feed pipe54includes an outer wall54A that includes one or multiple openings54B formed about the terminal end portion of the feed pipe. SeeFIG. 4. In the embodiment shown inFIGS. 4 and 5, there is provided two aligned openings54B in the wall54A. This enables two nozzle holders56to be connected to the feed pipe54with each nozzle holder communicatively connected to one of the openings54B in the wall of the feed pipe. An end cap54C is secured to the terminal end of the feed pipe54. Thus, it is appreciated that, in the case of this embodiment, backwash is pumped from the manifold52into the feed pipe54and into the two nozzle holders56secured to the terminal end portion of the feed pipe. It is appreciated that a single nozzle holder56can be secured to a feed pipe54. This is achieved by providing a single opening54B into the wall54A and communicatively connecting the single nozzle holder56to the single opening formed in the feed pipe.

With reference toFIGS. 10-15, the nozzle holder56is shown therein. Nozzle holder56includes a main conduit56A having a longitudinal axis56B. Main conduit56A includes an outer wall56C. Main conduit56is open to permit backwash to flow therein. Also forming a part of the nozzle holder56is a plurality of branch conduits56D. As illustrated in the drawings, the branch conduits56D are both longitudinally spaced and offset with respect to the longitudinal axis56B. As seen inFIGS. 10-15, the branch conduits56D project outwardly from the outer wall56C of the main conduit56A. Each branch conduit56D includes a through opening56E. Through openings56E permit backwash to flow through the respective branch conduits56D.

The length of the nozzle holder56can vary. There are two exemplary embodiments shown in the drawings. In one exemplary embodiment, there is provided four branch conduits56D (FIGS. 10-14) and in the other exemplary embodiment (FIG. 15), the nozzle holder includes eight branch conduits. It is appreciated that the size and length of the nozzle holder56, as well as the number of branch conduits56D, can vary depending upon specific applications.

Nozzle holder56includes an inner end portion and an outer end portion. It is the inner end portion that connects to the feed pipe54. The outer end of one embodiment of the nozzle holder56includes a rounded or spherical tip56F. SeeFIG. 5. The reason for this is that it is possible for the nozzle holder56to inadvertently fall downwardly into engagement with drum14while the drum is rotating. The rounded or spherical tip56F may minimize or reduce the possibility of damage to the nozzle holder56, nozzles58and/or the associated feed pipe54.

In order to mount and connect the nozzle holders56to the feed pipes54, each nozzle holder is provided with a connector56G disposed on the inner end portion of the nozzle holder. As seen in the drawings, particularlyFIGS. 10 and 15, the connector56G assumes a generally C-shape which is configured to wrap around a portion of the feed pipe54. Note that connector56G includes a pair of screw openings56H. The screw openings can be threaded or non-threaded. When a pair of nozzle holders56are connected to the feed pipe54, as illustrated inFIG. 6, it follows that one connector56G associated with one nozzle holder will include threaded openings while the other connector associated with the other nozzle holder will simply include a screw sleeve for receiving a pair of screws60. Screws60are extended through one connector56G into the threaded screw openings of the other connector and the screws are tightened to pull both connectors into a tight fit around the feed pipe54. Note that the nozzle holders56include a portion that projects through the connector56G. This is referred to as a stub end56I. SeeFIGS. 6, 10 and 15. Stub end56I of the nozzle holder56is designed to be inserted into opening54B formed in the wall54A of the feed pipe54. An O-ring62is interposed between the wall54A of the feed pipe54and the stub end56I in order to form a liquid tight seal between the feed pipe54and the nozzle holder56. Note inFIG. 6that each connector56G includes an O-ring recess formed in the stub end of56I for receiving the O-ring62. As shown inFIG. 6, the O-ring62forms a liquid tight seal between the feed pipe54and the connector56G.

A series of nozzles58are detachably secured to the outer terminal ends of the branch conduits56D. As shown inFIG. 9, nozzle58includes a main body58A, an orifice58B, and a connecting portion58C. Various means can be employed for detachably securing the nozzles58to the branch conduits56D. It is preferred that the nozzle design be such that the nozzles can be quickly and easily attached and detached from the branch conduits56D. In one embodiment, the nozzles58are attached to the terminal ends of the branch conduits56D via a twist and lock bayonet connection. In order to provide a liquid tight seal between the branch conduits56D and the nozzles58, there is provided a gasket59that is interposed between the nozzles58and the terminal ends of the branch conduits56D. SeeFIG. 4.

Nozzles58and branch conduits56D can be spaced and oriented in various ways. In the exemplary embodiments shown in the drawings, pairs of branch conduits56D are grouped. Each pair of branch conduits56D is offset with respect to the longitudinal axis56B of the main conduit56A. In addition, the branch conduits56D of each pair project in opposite directions from the outer wall56C. SeeFIGS. 12 and 14, for example. In this exemplary embodiment, nozzles58are aimed such that the backwash spray from each nozzle passes over or under a portion of the nozzle holder56. This arrangement enables the spacing between the nozzles58and the targeted filter media20to be increased for a particular spacing that exists between successive filter discs16. Hence, for a given nozzle design, this tends to increase the effective spray pattern of the nozzle.

FIGS. 4-6illustrate how the nozzle holders56are secured to the feed pipe54. In this embodiment, two nozzle holders56are cantilevered from the feed pipe54. At the same time, the nozzle holders56form a liquid tight seal with the feed pipe54. Each C-shaped connector56G wraps around a portion of the feed pipe54. As shown inFIG. 6, screws60secure the two connectors56G together. When tightened, the connectors56G pull the stub end56I of each nozzle holder into an opening54B formed in the feed pipe. With the presence of the O-ring62interposed between the feed pipe and the connector56G of the nozzle holder, a liquid tight seal is provided. Thus, it is appreciated that backwash pumped into the feed pipe54is directed into each of the nozzle holders56and through the nozzles58mounted on the branch conduits56D. It should be appreciated that a single nozzle holder56can be secured in similar manner to the feed pipe. In this case, one might use a complimentary C-shaped connector, not associated with another nozzle holder, in order to connect to a connector56G that is associated with the nozzle holder that is to be connected to the feed pipe.

As indicated above, in some embodiments the connector56G functions to connect the nozzle holder56to the feed pipe54. In other embodiments, the connector56G functions to connect one nozzle holder to another nozzle holder. For example, in one embodiment two nozzle holders can be connected in end-to-end relationship by two cooperating connectors.

In one exemplary embodiment, the nozzle holder56is constructed of molded plastic. In this exemplary embodiment, this means that the main conduit56A, branch conduits56D and the connector56G comprise a single piece of molded plastic. In other embodiments, the nozzle holder56includes two or more of its functional components permanently secured together. In this embodiment, for example, the branch conduits56D are permanently secured to the main conduit56A. In another example, both the branch conduits56D and the connector56G are permanently secured to the main conduit56A. When plastic is employed for the nozzle holder56or portions thereof, permanent connections can be made ultrasonically (for example, by ultrasonic welding) or heat welding and sealing (for example, heat or hot plate welding). The term “permanently secured” excludes connections by mechanical fasteners, such as screws, bolts and rivets. The specification and claims used the term “operatively connected”. “Operatively connected” means that two structures can be directly or indirectly connected. For example, there is a reference to a plurality of nozzle holders operatively connected to the feed pipes for receiving backwash therefrom. Here the plurality of nozzle holders might not be directly connected to the feed pipes, but they may be indirectly connected because backwash flows from the feed pipes into the plurality of nozzle holders.

There are many advantages to the backwashing system, particularly to the nozzle holder56and the manner in which the nozzle holder is communicatively connected to the feed pipe54. First, the nozzle supporting structure secured to the end of the feed pipes54is of a lightweight construction. This significantly reduces the load on the feed pipes54and reduces the torque required to rotate the manifold52during cleaning operations. Further, the design of the nozzle holder56minimizes the components used to support the nozzles58. The design of the feed pipe54and nozzle holder56reduces the number of welded and screw joints and this in turn reduces the potential for joint leakage. In the end, the design and arrangement of the feed pipes and nozzle holder reduces costs, and reduces assembly and delivery times. Further, the feed pipe and nozzle holder design is less bulky and enables the filter discs16to be stacked closer together around the drum14. By enabling more filter discs16per unit length of drum, this increases filter capacity for a given footprint and in the end, tends to reduce the overall cost of a disc filter in relationship to filtering capacity.

The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the scope and the essential characteristics of the invention. The present embodiments are therefore to be construed in all aspects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.