In some embodiments, the aquatic and/or recreational water to be treated may include water for human or veterinary applications. For example, the aquatic or recreational water may be used for swimming. The aquatic and/or recreational water may be associated with a pool, spa, hot tub, water park, water fountain, aquarium, zoo, animal reserve, and the like. Typically, the regenerative media filter vessel may be positioned in the vicinity of the source of the aquatic and/or recreational water. In some embodiments, the regenerative media filter vessel may be remote from the source of the aquatic and/or recreational water.

While embodiments described herein generally refer to aquatic and recreational facilities water, such an application is exemplary. It should be understood that the systems disclosed may be employed for filtration of any fluid to be filtered with a particulate media filter. For instance, systems disclosed herein may be employed for filtration of potable water, aquaculture, irrigation, stormwater management, water for use of oil and gas processing, and other applications.

The regenerative media filter vessel may be of a size suitable for processing between 25 and 3000 gallons per minute (GPM) of water. For example, the regenerative media filter vessel may be sized to process between about 25 GPM and about 100 GPM, between about 50 GPM and about 250 GPM, between about 150 GPM and about 300 GPM, between about 200 GPM and about 400 GPM, between about 300 GPM and about 450 GPM, between about 400 GPM and about 500 GPM, between about 450 GPM and about 800 GPM, between about 600 GPM and about 1000 GPM, between about 800 GPM and about 1500 GPM, between about 1000 GPM and about 2000 GPM, between about 1500 GPM and about 2500 GPM, or between about 2000 GPM and about 3000 GPM. The regenerative media filter vessel may comprise more than one vessel, arranged in series or in parallel. Generally, the size and arrangement of regenerative media filter vessels may vary with the size of aquatic or recreational structure to be filtered.

In accordance with one or more embodiments, a water filtration system may include a regenerative media filter vessel. Examples of regenerative media filter vessels are disclosed in PCT/US2019/062373 filed Nov. 20, 2019 titled “REGENERATIVE MEDIA FILTER AIR SCOURING APPARATUS AND METHOD,” PCT/US2019/056850 filed Oct. 18, 2019 titled “REGENERATIVE MEDIA FILTER AND RELATED METHODS,” and WO 2019/055903 filed Sep. 17, 2018 titled “SAND FILTER LED STATUS LIGHT,” all assigned to Evoqua Water Technologies LLC, Pittsburgh, PA, the disclosures of which being incorporated herein by reference in their entireties for all purposes.

An example of a regenerative media filter vessel is illustrated in FIG. 1 in an exploded view. The regenerative media filter vessel 100 includes a vessel housing 102, a vessel top 104, and a vessel base 106. The vessel top 104 includes top cover 108, and vessel outlet 114. Housed within the vessel housing 102 is tube sheet assembly 116 including a plurality of tube elements 122. The tube sheet assembly 116 is sealed to the vessel top 104 using tube sheet gasket 116a. The top cover 108 is sealed to the tube sheet assembly 116 using top cover gasket 108a. The top cover 108 and tube sheet assembly 116 are connected to the vessel top 104 using top cover fasteners 108b. The vessel base 106 includes a vessel inlet 112 comprising a diffuser 124 that is sealed to the vessel base 106 using an inlet gasket 112a and inlet fasteners 112b. The vessel base 106 also includes a vessel drain 120, with both the top cover 108 and vessel base 106 including vacuum ports 118a, 118b, respectively.

The regenerative media filter vessel may be manufactured from any suitable material that is compatible with aquatic environments and can maintain internal pressures consistent with those applied from pumps and other equipment. For example, the regenerative media filter vessel may be manufactured from polymeric materials such as polyvinyl chloride (PVC), fiberglass-reinforced polymer (FRP), polyethylene (PE), or polypropylene (PP). Other suitable materials are known in the art. An exemplary material is PVC and it provides numerous advantages over other materials. PVC is a relatively inexpensive material that is readily available that can withstand applied pressures beyond those of the systems described herein. PVC has excellent chemical compatibility with the chemicals found in aquatic environments (for example, salts, hypochlorite ions, and ozone) and thus has a notably long working life cycle before needing to be replaced. Certain thicknesses of PVC, such as Schedule 40, have attained regulatory approval, for example NSF-50 that sets a design pressure rating of 4× the maximum operating pressure, for use in residential and commercial aquatic settings. Further, PVC is a highly workable material, readily taking to solvent welding to form continuous structures and surface treatments to improve UV resistance and weatherability.

The regenerative media filter vessel may have a ratio of a height to an inner diameter of at least 0.25:1. As used herein, the “height” refers to the distance measured between the centerline of the diffuser and the maximum of the radius of curvature of concave lower portion of the regenerative media filter vessel. The height to inner diameter ratio may be used, at least in part, to determine the position of a flow diffuser within the regenerative media filter vessel. In some embodiments, the regenerative media filter vessel may have a ratio of the height to the inner diameter of no more than 0.55:1. For example, the ratio of the height to the inner diameter of the regenerative media filter vessel may be from 0.25:1 to 0.30:1, from 0.275:1 to 0.35:1, from 0.30:1 to 0.375:1, from 0.35:1 to 0.40:1, from 0.375:1 to 0.425:1, from 0.40:1 to 0.475:1, from 0.425:1 to 0.50:1, or from 0.45:1 to 0.55:1. An exemplary regenerative media filter vessel has a ratio of height to inner diameter of 0.46.

In some embodiments, the regenerative media filter vessel may have a ratio of the radius of curvature of the concave lower portion to the inner diameter of at least 0.5:1. A ratio of 0.5:1 describes a perfect hemisphere. As the ratio increases, the concavity of the concave lower portion is reduced. If this ratio is too large, the concave lower portion may, in effect, be a flat portion that may not allow for a flow of water to have a uniform flow distribution within the regenerative media filter vessel. The radius of curvature of the concave lower portion to inner diameter ratio may be used, at least in part, to determine the position of the diffuser within the regenerative media filter vessel. In some embodiments, the regenerative media filter vessel may have a ratio of the radius of curvature of the concave lower portion to the inner diameter of no more than 2:1. For example, the regenerative media filter vessel may have a ratio of the radius of curvature of the concave lower portion to the inner diameter from 0.5:1 to 1:1, from 0.75:1 to 1.25:1, from 1:1 to 1.5:1, from 1.25:1 to 1.75:1, or from 1.5:1 to 2:1.

In some embodiments, the inlet of the regenerative media filter vessel includes a diffuser fluidly connected to the inlet and disposed within the regenerative media filter vessel. The diffuser is designed and constructed to provide for a uniform fluid flow distribution within the regenerative media filter vessel. By “uniform fluid flow distribution,” it is meant that flow entering the regenerative media filter vessel has a reduced flow velocity as compared to the flow velocity of water entering the diffuser, is substantially laminar, and is symmetric about a central vertical axis of the regenerative media filter vessel over a majority of the height of the vessel.

Uniform fluid flow distribution of water entering the vessel is a consideration for the efficiency of filtration and the coating of the plurality of tube elements with particulate media. Fluid flow that is not uniformly distributed may, for example, reduce the effective media coating thickness on some or all of the plurality of tube elements. Uncoated surfaces of tube elements, or surfaces with less than the minimum media coating thickness, may contribute to filter breakthrough and a reduction in filtrate quality. Further, turbulent flow into the regenerative media filter vessel may inadvertently deposit particulate media onto surfaces where it is not intended, increasing particulate media use and costs. A uniform fluid flow distribution of water entering the vessel may aid in uniformly coating the plurality of tube elements and thus reduce cycle time of the regenerative media filter vessel.

In some embodiments, the diffuser is positioned within the regenerative media filter proximate the concave lower portion. The diffuser generally includes a conduit having a plurality of apertures defined in at least a lower side of a wall of the conduit. The plurality of apertures may be configured, that is, sized and shaped, to allow a particulate media within the regenerative media filter vessel to pass through. The diffuser is generally configured to receive a flow of water at any velocity or flow characteristics and output a smoother flow with a reduced velocity and more uniform flow distribution. For example, the diffuser may be configured to receive a turbulent flow of water, such as water from a pump at a high velocity and provide for a reduction in the flow velocity of water into the regenerative media filter vessel. In some embodiments, the diffuser may be configured to provide for a reduction in the flow velocity into the regenerative media filter vessel of at least 50% relative to water provided to the diffuser from the at least one pump. For example, the diffuser may be configured to reduce a 300 GPM flow with a velocity of 12 feet per second (fps) down to between 3-4 fps. Examples of the reduction in velocity of water pumped through the diffuser and into the vessel are illustrated in FIGS. 2A and 2B.

Example embodiments of diffusers are illustrated in FIGS. 3A-3G and FIGS. 4A-4J. In the illustrated examples, the diffusers include a conduit and a plurality of apertures positioned in at least a lower wall of the conduit. The plurality of apertures may be transverse, that is, orthogonal, to the axis of flow through the diffuser, as shown in FIGS. 3A-3G, 4E, 4I, and 4J. Alternatively, the plurality of apertures may be longitudinally extending apertures, that is, parallel to the axis of flow through the diffuser. Example embodiments of diffuser having longitudinally extending apertures are illustrated in FIGS. 4A, 4B, 4F, and 4G. In some embodiments, the plurality of apertures may be circular apertures, such as the embodiments illustrated in FIGS. 4C, 4D, and 4H. In embodiments that include circular apertures, the circular apertures may be arranged transverse to or longitudinally with the axis of flow through the diffuser. Alternatively, or in addition, circular apertures may be positioned in any pattern independent of the axis of flow through the diffuser. In some embodiments, the plurality of apertures spans a portion of a perimeter of the diffuser. For example, the plurality of apertures may be located only on the perimeter of a lower portion or lower region of the diffuser, such as the lower portion of the generally cylindrical diffusers illustrated in FIGS. 3A-3G and 4A-4J. Alternatively, the plurality of apertures may span any portion of perimeter of the diffuser to provide the desired reduction in flow velocity. The number of apertures may be any suitable number, that is, the number of apertures may be from 1 to 100, inclusive. In the diffuser configuration shown in FIGS. 3A-3G and 4A-4J that is generally cylindrical, water introduced to the diffuser can flow down and away from the diffuser.

The overall length of the diffuser, that is, the portion of the diffuser that is disposed with the regenerative media filter vessel, is sufficient such that the water directed out of the diffuser and into the regenerative media filter vessel can uniformly contact each of the plurality of tube elements. A diffuser length that is too short may not be able to include a sufficient number of apertures to achieve the desired reduction in flow velocity and/or may not be able to direct water to each of the plurality of tube elements.

The plurality of apertures may be sized, that is, in length and width, and shaped to provide for a reduction in the flow velocity of water through the diffuser. For example, FIGS. 5 and 6 illustrate flow velocity and pressure contours of flow into a regenerative media filter vessel equipped with the diffuser illustrated in FIGS. 3A-3G showing the reduction in flow velocity into the vessel. Apertures that are too large may not have sufficient water pressure to direct water introduced into the vessel into contact the plurality of tube elements, and apertures that are too small may be prone to becoming clogged with particulate media as water flows within the vessel. The apertures may have a minimum dimension (that is, a length or width) of at least 0.5 inches to avoid being clogged with particulate media.

In some embodiments, a sum of an open area of the plurality of apertures may be at least 1.5 times an entrance area of the diffuser. As used herein, the “entrance area” of the diffuser refers to the area of the opening in the connection flange of the diffuser where water is directed into. For a generally cylindrical diffuser as disclosed herein, the open area of the diffuser is the area of the perpendicular cross-section of the diffuser, πr². Other diffuser shapes are within the scope of this disclosure. In some embodiments, the sum of the open area of the plurality of apertures may be no more than 5 times the entrance area of the diffuser. For example, the regenerative media filter vessel may have a diffuser that has a sum of the open area of the plurality of apertures from 1.5 to 2.5 times the entrance area of the diffuser, from 2 to 3 times the entrance area of the diffuser, from 2.5 to 3.5 times the entrance area of the diffuser, from 3 to 4 times the entrance area of the diffuser, from 3.5 to 4.5 times the entrance area of the diffuser, or from 4 to 5 times the entrance area of the diffuser. Exemplary diffusers may have a sum of the open area of the plurality of apertures between 2 and 3.5 times the entrance area of the diffuser. The increased open area of the plurality of apertures of the diffuser may be sufficient to provide for a reduction in flow velocity into the regenerative media filter vessel while maintaining sufficient water pressure into the regenerative media filter vessel for a desired level of filter vessel performance and/or coating of the plurality of tube elements with particulate media.

In some embodiments, the pattern of the plurality of apertures along the length of the diffuser may be asymmetric. The asymmetry may be in any aspect of the diffuser, such as a variable length and/or width of each of the plurality of apertures and/or a variable spacing between each of the plurality of apertures. For example, each of the plurality of apertures of the diffuser may have a variable width. Embodiments of a diffuser having apertures with varying width and/or diameter are illustrated in FIGS. 4H, 4I and 4J, where the width and/or diameter of the apertures decreases along the length of the diffuser from the entrance to the capped end. Alternatively, or in addition, each of the plurality of apertures of the diffuser may have a variable spacing between the apertures. An embodiment of a diffuser having apertures with varying spacing is illustrated in FIG. 4E, where the apertures are depicted as uniformly sized rectangular transverse apertures that have increased spacing along the length of the diffuser from the entrance to the capped end. In this configuration, there is an increased number of apertures located at the entrance to the diffuser and fluid flow into the diffuser may be more effectively diffused as the flow travels along the length of the diffuser and into the regenerative media filter vessel. In some embodiments, the diffuser may contain any combination of aperture shapes, dimensions, and/or spacings, and the invention is not limited to the shapes, dimensions, and/or spacing between apertures in the diffuser.

In some embodiments, each of the plurality of apertures may have uniform or identical dimensions. For example, FIGS. 3A-3G and 4E illustrate embodiments of diffusers with apertures shown as rectangular openings where the width of each aperture is uniform, that is, identical in size and shape, and positioned closer to the capped end of the diffuser. As another example, FIGS. 4B, 4F, and 4G illustrate embodiments of diffusers with apertures shown as uniformly shaped longitudinally extending oblong apertures where each aperture is identical in size and shape. Alternatively, each of the plurality of apertures may have a dimension that is non-uniform, that is, the aperture may be tapered. An embodiment of a diffuser with tapered longitudinally extending apertures is illustrated in FIG. 4A. In embodiments with circular apertures, each of the circular apertures may have substantially the same diameter, such as the embodiments illustrated in FIGS. 4C-4D. Alternatively, each of the circular apertures may have different diameters, such as the embodiment illustrated in FIG. 4H. In some embodiments, the length of at least one of the plurality of apertures of the diffuser may be the same as the length of at least one other of the plurality of apertures. Alternatively, or in addition, the length of at least one of the plurality of apertures of the diffuser may be different from the length of at least one other of the plurality of apertures. Alternatively, the length of each of the plurality of apertures of the diffuser may be different.

In some embodiments, the width of at least one of the plurality of apertures of the diffuser may be the same as the width of at least one other of the plurality of apertures. Alternatively, or in addition, the width of at least one of the plurality of apertures of the diffuser may be different from the width of at least one other of the plurality of apertures. For example, the length of each of the plurality of apertures and the width of each of the plurality of apertures of the diffuser may be the same, such as the apertures illustrated in FIGS. 3A-3G. In FIGS. 3A-3G, the apertures are configured as rectangular slots that are identical in length and width positioned orthogonal to the flow axis through the diffuser.

In some embodiments, the diffuser may include one or more internal structures configured to reduce flow velocity of fluid before passing through the plurality of apertures. For example, a diffuser may include one or more internal structures, such as baffles, positioned above the plurality of apertures to guide fluid towards the plurality of apertures. An example of a diffuser including internal projections is illustrated in FIG. 4G. One of skill in the art can appreciate that the total number, physical dimensions, position along the diffuser for each of the plurality of apertures, and any other internal structural features of the diffuser may be chosen for a desired level of performance, for example, flow velocity reduction, tube element coating efficiency, or overall filtration performance.

In some embodiments, the housing of the regenerative media filter vessel may include a concave lower portion that is centered about a vertical axis of the vessel. The concave lower portion may be configured to promote the flow of water, and any component of the water such as particulate media, up and through the vessel. The concave lower portion prevents, at least in part, clogging of the particulate media as it passes through the apertures of the diffuser. The concave lower portion further prevents buildup of particulate media in certain areas of the regenerative media filter vessel. The concave lower portion may also facilitate the draining of liquid and spent particulate media out of the regenerative media filter vessel prior to replacement of the particulate media. Examples of regenerative media filter vessels having a concave lower portion 130 are illustrated in FIGS. 1, 7A, and 7B. With reference to FIGS. 7A and 7B, the diffuser 124 inserted into inlet 112 may be positioned over the approximate point of highest curvature of the concave lower portion 130 (part of the vessel base 106) over the drain 120. In this configuration, water that is pumped through the diffuser 124 is able to follow the curvature of the concave lower portion 130 and flow up the height of the regenerative media filter vessel in a controlled and uniform fashion to ensure that water, and in some instances, fresh particulate media as described herein, can contact the plurality of tube elements within the regenerative media filter vessel. As shown in FIGS. 7A and 7B, the concave lower portion may be circular in profile, that is, have a circular arc. In other embodiments, the concave lower portion may also be elliptical in profile. In any embodiment of a regenerative media filter vessel having a concave lower portion, a fillet may be added to the junction between the concave lower portion and the vertical wall of the vessel to provide a smooth transition between the two sections.

In a regenerative media filter vessel, the particulate media may be removed from the plurality of tubes once the filtration performance has eroded, indicating that the interstitial spaces between media particles are clogged with contaminants. Water is typically directed through the plurality of tube elements or the plurality of tube elements are mechanically agitated to facilitate media removal. Fresh media is typically added back onto the plurality of tube elements in a pre-filtration process where new particulate media is added to the vessel and water is introduced to the inlet of the regenerative media filter vessel and through the diffuser to suspend the particulate media and allow it to build up on the surfaces of the plurality of tube elements. In some embodiments, the coating of particulate media on the plurality of tube elements may be up to about 5 mm thick, for example, from 2-5 mm thick. In some embodiments, the efficiency and timescale of the pre-filtration process may be determined by the position of the diffuser along the height of the regenerative media filter vessel.

The position of the diffuser within the regenerative media filter vessel, that is, the height at which it is positioned and its overall length into the regenerative media filter vessel, may be determined by a number of factors that provide a flow of water with a desired level of performance. In general, for regenerative media filter vessels described herein that include a plurality of tube elements, the diffuser should be positioned between the lowermost extent of the plurality of tube elements and the concave lower portion. The dimensions of the space between the lowermost extent of the plurality of tube elements and the concave lower portion may depend on the length of the tube elements, which in some embodiments, may be from 1 foot to 6 feet in length. For example, the position of the diffuser along the height of the regenerative media filter vessel may be determined by at least the ratio of the height to the inner diameter of the regenerative media filter vessel and a radius of curvature of the concave lower portion

such that, in operation, a flow of water directed out of the diffuser and into the regenerative media filter vessel has a minimum flow velocity near a bottom of the regenerative media filter vessel that exceeds a settling velocity of the particulate media throughout the water in the regenerative media filter vessel. Other factors that may be used to determine the position of the diffuser within the regenerative media filter vessel include, but not limited to, the length of the diffuser, the diameter of the diffuser, the ratio of the inner diameter to the radius of curvature of the concave lower portion, and the length, number, and size of each of the plurality of apertures and the relative spacing therebetween.

In some embodiments, there may be a minimum distance between the centerline of the diffuser and the concave lower portion of the regenerative media filter vessel. This minimum distance may be set to, at least in part, reduce clogging of the apertures of the diffuser with the particulate media. For example, if the diffuser is positioned too close to the concave lower portion, the diffuser may become clogged with particulate media and/or the concave lower portion may become filled with particulate media and not allow it to pass into the regenerative media filter vessel. On the other hand, if the diffuser is positioned too far from the concave lower portion, the particulate media may not be able to coat the full length of each of the plurality of tube elements and/or the coating process may not occur on a timescale that is practical to an end user or operator. In addition, a diffuser that is positioned too far from the concave lower portion may not allow for fluid flow to reach the bottom of the regenerative media filter vessel. This may result in the formation of stagnant zones into which the particulate media may settle and accumulate during a tube element coating process or during filter operation. Thus, the position of the diffuser may be determined by measuring the amount of time necessary to properly coat the plurality of tube elements with particulate media.

For the particulate media to build up a sufficient coating on the tube elements, the particulate media should be in suspension such that it can contact the tube elements and allow for additional media-to-media contact. In such implementations, for the particulate media to remain suspended, the flow of water in the regenerative media filter vessel from the concave lower portion into the plurality of tube elements should have an upward velocity component that exceeds the settling velocity of the particulate media in water under gravity. If this condition is not met, the particulate media will settle to the bottom of the regenerative media filter vessel without coating the plurality of tube elements. The settling velocity of the particulate media is a function of the density of the media, which for typical media used in a regenerative media filter vessel, such as perlite, is about 1.1 g/cm³. In the context of the present disclosure, for the particulate media to remain suspended in the regenerative media filter vessel such that it can effectively coat the plurality of tube elements, the flow of water should be sufficient to overcome the force of gravity acting on the particulate media as it moves through the water, which in the context of this disclosure may be considered a dilute suspension of particulate media. This relationship may be illustrated by Stokes' equation for laminar flow, which describes the relationship between particle velocity, gravitational acceleration, and the viscosity of the medium the particle travels in. The settling velocity of a particle through water may be described by the following equation:

v
=

2
9

⁢

(

ρ
s

-

ρ
w

)

⁢

g
⁢

r
2

μ

Where:

- ν=settling velocity of particle (m/s);
- ρ_s=density of particle (kg/m³);
- ρ_s=density of water (kg/m³);
- g=gravitation acceleration (m/s²);
- r=particle radius (μm); and
- μ=viscosity of water (kg/(s·m)).
  
  As a non-limiting example, perlite particulate media having a specific gravity of 2.3 and a particle radius of 160 μm (which is the 90^thpercentile in the typical measured perlite particle size distribution) would have a settling velocity in water of approximately 0.02 m/s. Thus, water flow within a regenerative media filter vessel of this disclosure having a velocity component in the upward direction greater than 0.02 m/s would keep these particles in suspension within the regenerative media filter vessel.

In some embodiments, the position of the diffuser in the regenerative media filter vessel may be determined by at least a radius of curvature of the concave lower portion and a ratio of a height to an inner diameter of the regenerative media filter vessel. The length of the diffuser, the position of the diffuser, and the inner diameter of the regenerative media filter vessel, in addition to the radius of curvature of the concave lower portion and the ratio of height to inner diameter of the regenerative media filter vessel, may be chosen such that, in operation, the diffuser provides a uniform fluid flow distribution of a flow of water directed into the regenerative media filter vessel. As noted herein, the ratio of the inner diameter to radius of curvature may be additionally used, at least in part, to determine the position of the diffuser within the regenerative media filter vessel.

In some embodiments, the position of the diffuser along a height of the regenerative media filter vessel may be determined by at least the ratio of the height to the inner diameter of the regenerative media filter vessel and the radius of curvature of the concave lower portion such that, in operation, a flow of water directed out of the diffuser and into the regenerative media filter vessel has a flow velocity profile having a highest flow velocity at the lower portion and decreasing in velocity as the water approaches a top of the regenerative media filter vessel. The flow velocity of water within the regenerative media filter vessel may not be the same throughout the vessel. Rather, flow velocity may be a continuum, having the greatest magnitude at a point closest to the inlet and decreasing along the height of the regenerative media filter vessel such that the magnitude is essentially zero at the top of the regenerative media filter vessel where the tube sheet is positioned. This is illustrated in FIGS. 2A and 2B, where the water entering the diffuser has high velocity at the inlet of the regenerative media filter vessel and diffuses throughout. There is also an area of high velocity that is in the immediate area near the outlet, as illustrated in FIGS. 2A and 2B, that is separated from the continuum of water velocities within the main interior of the regenerative media filter vessel by the tube sheet.

Health Departments typically regulate a turnover rate of water filtration in a swimming pool. For instance, Health Departments may instruct a maximum turnover rate. The systems disclosed may be operated to have an aquatic or recreational water turnover rate of at most 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours.

Flow rate of water being filtered through the media filter may have an effect on turnover rate. In accordance with certain embodiments, the system may be operated at a flow rate of at least a threshold flow rate to provide the desired turnover rate. In such embodiments, the systems disclosed herein may have flow rates monitored or controlled. The systems disclosed herein may be operated in a cleaning or drain mode responsive to the flow rate being lower than a threshold flow rate.

The threshold flow rate may be calculated by the following equation:

F
=

V
t

Where:

- F=threshold flow rate (GPM);
- V=volume of water in swimming pool (g); and
- t=maximum turnover time (min).

A regenerative media filter vessel comprising a plurality of tube elements with porous media, such as a DEFENDER® filter, may be cleaned by expelling the media and contaminants from the plurality of tube elements within the vessel and into suspension. The cleaning process generally allows the tube elements to receive a fresh coating of porous media once the media particles reattach to the tube elements. After cleaning, the tube elements may be recoated with media using a coating or pre-filtering process. The recoated media filter may be placed back into service.

Systems disclosed herein may employ a hydraulic cleaning process. The hydraulic cleaning process generally employs a recirculating pump and one or more valves to functionally achieve reverse recirculation of water through the plurality of tube elements. The one or more valves may be manually actuated by a user or service provider to open or close in a predetermined sequence to perform the hydraulic cleaning process. The hydraulic effect from the actuation sequence may dislodge the media from the plurality of tube elements and send it into suspension, without causing significant mechanical stress on the plurality of tube elements. Specifically, the hydraulic process may effectively remove media and contaminants from the plurality of tube elements without physically raising and lowering the plurality of tube elements.

Systems described herein may be operated in a cleaning mode. The cleaning mode may include directing water through the media filter in a direction that is opposite that of the filtration mode. The flow of water in the second direction may cause the particulate media to be suspended in the filtered water. The cleaning mode may generally comprise manually closing a feed valve to block passage of water into the regenerative media filter vessel and closing an end use valve to block passage of the filtered water out of the regenerative media filter vessel. One or more recirculation valves may be opened to allow passage of the filtered water through a recirculation line of the regenerative media filter vessel.

Systems as described herein may be operated in the cleaning mode for a period of time sufficient to decrease the internal pressure of the regenerative media filter vessel to be within an operating pressure range associated with restored operation of the regenerative media filter. When the internal pressure of systems as described herein has been restored to normal operating level, the systems may be returned to the filtration mode.

Systems described herein may be operated in a pre-filtration mode. The pre-filtration mode may comprise directing the water through the regenerative media filter vessel in the first direction. The pre-filtration mode may be configured to coat the plurality of tube elements with the particulate media in preparation for the filtration mode. The pre-filtration mode may generally comprise operating the system with the same valve configuration as the cleaning mode but reversing directionality of the water through the recirculation line. Thus, during the pre-filtration mode, the feed valve may be closed to block passage of water into the system and the end use valve may be closed to block passage of the filtered water out of the system. One or more recirculation valves may be opened to allow passage of the filtered water through the recirculation line of the system. The one or more valves may be manually actuated by a user or service provider to open or close in a predetermined sequence to perform the pre-filtration mode.

The systems disclosed herein may be operated in the pre-filtration mode for a period of time sufficient to coat the plurality of tube elements with the particulate media. The period of time may be between about 8-15 minutes. The period of time may be between about 8-10 minutes, 10-12 minutes, or 12-15 minutes. After coating the tube elements in the pre-filtration mode, the systems disclosed herein may be returned to operating in the filtration mode.

In certain embodiments, the systems described herein may be operated in the pre-filtration mode upon start-up. In such embodiments, the system may be loaded with water or feed water prior to operation in the pre-filtration mode. After a period of time sufficient to coat the plurality of tube elements, the systems described herein may be operated in the filtration mode, as previously described.

The regenerative media filter vessel may be periodically drained. During cycled use, as previously described, contaminants may build up within the media adsorbed onto the plurality of tube elements. The contaminants may be removed from the porous media by operating in the cleaning mode. However, the contaminants are generally retained within the regenerative media filter vessel during and after the cleaning mode, until the media filter vessel is drained. Thus, the systems described herein may be operated in a drain mode. The drain mode may include opening a drain valve on the regenerative media filter vessel and draining the regenerative media filter vessel of water, particulate media, and contaminants. The drain mode may additionally comprise opening a feed valve to flush the regenerative media filter vessel. A regenerative media filter vessel having a drain 120 is illustrated in FIGS. 1, 7A, and 7B. After draining, the particulate media of the systems may be replaced. In some embodiments, the systems described herein may be operated in the drain mode responsive to a period of time of operation in the filtration mode being less than about 4 hours, less than about 3 hours, less than about 2 hours, less than about 1 hour, or less than about 0.5 hours from a predetermined threshold value. The systems described herein may be operated in the drain mode responsive to a period of time of operation in the filtration mode being less than about 10 minutes, less than about 5 minutes, less than about 2 minutes, less than about 1 minute, less than about 30 seconds, less than about 10 seconds, or less than about 1 second from a predetermined threshold value. The predetermined threshold value may be the threshold value which triggers operation in the drain mode.

EXAMPLES

The function and advantages of these and other embodiments can be better understood from the following examples. These examples are intended to be illustrative in nature and are not considered to be in any way limiting the scope of the invention.

Example 1A
Vessel Fabrication

As an illustrative example of the invention described herein, a regenerative media filter vessel was designed and constructed from FRP. Embodiments of regenerative media filter vessels including a tube sheet including a plurality of tube elements and a diffuser connected to the inlet are illustrated in FIGS. 1 and 8, with the general construction of the constructed regenerative media filter vessel illustrated in FIG. 1. With reference to FIG. 1, the illustrated regenerative media filter vessels include standard fittings on all connectors, for example, female NPT 1.5-inch connections for the drain 120 and vacuum connections 118a, 118b that are used for particulate media loading.

The overall dimensions of the designed and constructed regenerative media filter vessel, as illustrated in FIGS. 1 and 8, were chosen such that the unit would be able fit through a standard doorway, for example, approximately 80″ tall by 33″ wide, in the installation location. With reference to FIG. 8, the regenerative media filter vessel 800 included a vessel body 102, a vessel top 104, and a vessel base 106 having a concave lower portion 130. The vessel top 104 included top cover 108 secured to vessel body 102. Housed within the vessel body 102 was tube sheet assembly 116 having plurality of tube elements 122. Each of the plurality of tube elements 122 was 36″ long. The top cover 108 was sealed to the tube sheet assembly 116. The vessel base 106 included a vessel inlet 112 that included a diffuser 124, with the connection flange of the diffuser 124 sealed to the inlet 112 of the vessel base 106. The vessel base 106 also included a vessel drain 120, with both the top cover 108 and vessel base 106 including vacuum port 118a (vacuum port on base not shown), respectively.

The tube sheet assembly included both an upper tube sheet and a lower tube sheet configured to hold the plurality of tube elements fixed in position, with the assembly containing 367 tube elements. The lower tube sheet was manufactured from a ¾″ thick portion of the same material used to fabricate the regenerative media filter vessel and was designed to separate the unfiltered water in the lower portion of the regenerative media filter vessel from entering the upper portion of the regenerative media filter vessel. The upper ends of each of the plurality of tube elements, which included a metal lip, were secured to the lower tube sheet using a felt gasket. The upper tube sheet was manufactured from a ½″ thick portion of the same material as the lower tube sheet and was configured to direct water from the plurality of tube elements to the outlet. The tube sheet assembly, that is, the upper and lower tube sheets with the plurality of tube elements installed into the lower sheet, was secured together using a plurality of ⅜″ 316SS corrosion-resistant bolts that threaded into helical inserts pressed into the lower tube sheet. In operation, unfiltered water was forced through the particulate media coated tube elements, each of which provided about 0.6 ft²of filtration area, for a total of 220.2 ft².

Example 1B
Vessel Flow Modeling

As a further illustrative prophetic example of the invention described in this disclosure, the regenerative media filter vessel constructed in Example 1A was computationally rendered and had water flow modeled through it using CFD. The dimensions of the regenerative media filter vessel, the position, the dimensions, and number of apertures of the diffuser were chosen to provide for a reduction in flow velocity of water entering the regenerative media filter vessel. In particular, the diffuser modeled in this example had apertures of uniform width and spacing along the length of the diffuser. The flow into the diffuser was modeled using CFD for a regenerative media filter vessel as described herein that contained a plurality of tube elements. The modeled flow into the regenerative media filter vessel was set to an inlet flow velocity of about 3 m/s.

FIG. 9A illustrates the CFD computational domain (defined by the black border box around the plurality of tube elements) where the flow was modeled in the vessel from the inlet, through the diffuser, and out through the outlet at the top of the regenerative media filter vessel. FIG. 9B illustrates exemplary horizontal and vertical sectional fluid flow planes used for plotting velocity contours and vectors to observe the effects of the different diffuser designs on the flow within various locations of the regenerative media filter vessel. With reference to FIG. 9B, the flow through the regenerative media filter vessel was examined in the vertical planes V1 and V2, particularly directly below the diffuser. With continued reference to FIG. 9B, the flow through the regenerative media filter vessel was examined in the horizontal plane at plane H2 directly below the plurality of apertures of the diffuser, plane H4 directly above the upper wall of the diffuser, plane H5 at the midsection of the regenerative media filter vessel, and plane H6 below the tube sheet.

As noted herein, FIG. 5 illustrates velocity contour plots taken through a horizontal cross-section of the lower portion of a regenerative media filter vessel equipped with the diffuser illustrated in FIGS. 3A-3G and a plurality of tube elements installed. As is seen, the diffuser having uniformly shaped and spaced apertures transverse or orthogonal to the axis of flow reduced the velocity of the water directed into it from a value of approximately 3 m/s to a velocity of approximately 1 m/s at positions immediately in front of the apertures. The sharp corners and narrow width of the orthogonal apertures created small areas of high velocity directly at the apertures, but this velocity was reduced once the water entered the vessel. The diffuser allowed for a continued reduction in velocity as positions further away from the diffuser.

FIG. 6 illustrates a velocity contour plot taken through a horizontal cross-section of a center plane the regenerative media filter vessel equipped with the diffuser illustrated in FIGS. 3A-3G and a plurality of tube elements installed. The flow velocity of the water at this plane was reduced by at least 50% from the inlet velocity of approximately 3 m/s, with the majority of the water in this plane having flow velocities of less than 0.5 m/s. The contour plots indicated that the diffuser of this design was able to reduce the flow velocity of water entering the regenerative media filter vessel and to create a flow velocity continuum that allowed for the uniform distribution of water throughout the vessel with a smooth flow.

Example 2
Different Diffuser Designs

This prophetic example illustrates the flow characteristics for diffuser designs that vary in the orientation, size, pattern, and spacing between the plurality of apertures of the diffuser. The flow characteristics for each diffuser design were modeled using CFD using the vessel described in Examples 1A and 1B and under identical simulation conditions (that is, water at the same temperature and flow characteristics). Example geometries of the various regenerative media filter vessel components used to model the flow characteristics for each diffuser design are illustrated in