HK1227798B - High velocity cross flow dynamic membrane filter - Google Patents

Description

High-speed cross-flow dynamic membrane filter

Cross-reference to related applications

This application claims priority to U.S. Provisional Patent Application No. 62/095,356, filed December 22, 2014, the entire contents of which are incorporated herein by reference.

Background Art

The present invention relates to liquid membrane filtration, and more particularly to a high-speed cross-flow liquid membrane filter system and subsystem.

Currently, high-pressure membrane systems pump feedwater across the filtration membrane at a high enough velocity to prevent precipitated material from developing on the membrane surface, i.e., membrane 'clogging.' Maintaining a high cross-flow rate while achieving the benefits of membrane filtration through pumping requires a significant amount of energy.

Summary of the Invention

In one embodiment, a high-speed cross-flow dynamic membrane filtration system includes a disk-membrane assembly having a frame and at least two support shafts. Each support shaft defines a longitudinal axis about which a plurality of axially spaced membrane disks are positioned, wherein each shaft is further coupled to the frame. A permeate tube is coupled to each support shaft and is in fluid communication with the membrane disk associated with the support shaft. A container defines a processing chamber and is configured to removably support the disk-membrane assembly within the processing chamber. The container further includes a wall. The filtration system also includes a drive system. The permeate tube is configured to extend through a portion of the container wall when the disk-membrane assembly is positioned within the processing chamber. The permeate tube is further configured to be rotated by the drive system.

In one embodiment, a high-speed cross-flow dynamic membrane filtration system includes a disk-membrane assembly having a first support shaft and a second support shaft. Each support shaft defines a longitudinal axis about which a plurality of axially spaced membrane disks are positioned. A container defines a processing chamber and is configured to support the disk-membrane assembly within the processing chamber. When the disk assembly is positioned within the processing chamber, at least one plate is coupled to the container or to the disk-membrane assembly such that the at least one plate extends at least partially between the plurality of axially spaced membrane disks of the first support shaft and the plurality of axially spaced membrane disks of the second support shaft.

In one embodiment, a disk membrane assembly includes a frame comprising a first support portion at a first end, a second support portion at a second end, first and second bearings located at the first support portion, first and second bearings located at the second support portion, and a plurality of track members extending from the first end to the second end. A first support shaft and a second support shaft each define a longitudinal axis about which a plurality of axially spaced membrane disks are positioned. A permeate tube is coupled to each support shaft and is in fluid communication with the membrane disk associated with the support shaft. The permeate tube of the first shaft is supported by a first bearing located at the first support portion and by a first bearing located at the second support portion. The permeate tube of the second shaft is supported by a second bearing located at the first support portion and by a second bearing located at the second support portion.

In one embodiment, a method of operating a high-speed cross-flow dynamic membrane filtration system includes feeding a fluid stream into a pressure vessel, the vessel defining a process chamber containing a disk-membrane assembly, the assembly having a first support shaft and a second support shaft, wherein each support shaft defines a longitudinal axis about which a plurality of axially spaced membrane disks are positioned. The method also includes distributing the fluid stream over at least a portion of the disk-membrane assembly. The method further includes discharging a first portion of the fluid stream from the vessel. The method further includes discharging a second portion of the fluid stream from the vessel. The method further includes rotating the first and second support shafts in a first direction, the rotation including modulating a rotation rate in response to a flow rate of the second portion of the fluid stream.

In one embodiment, a disk-membrane assembly includes a support shaft defining a longitudinal axis, with a plurality of axially spaced membrane disks positioned about the longitudinal axis, wherein each membrane disk includes a disk body presenting a first surface and an opposing second surface. A first permeate carrier is in direct contact with the first surface, and a second permeate carrier is in direct contact with the second surface. A first filter membrane is in direct contact with the first permeate carrier, and a second filter membrane is in direct contact with the second permeate carrier.

Other features and aspects of the present invention will become apparent by consideration of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a cross-flow membrane treatment system.

2 is a perspective view of the cross-flow membrane subsystem of the processing system of FIG. 1 .

FIG. 3 is another perspective view of the cross-flow membrane subsystem of FIG. 2 .

4 is a perspective view of the vessel of the cross-flow membrane subsystem.

FIG. 5 is another perspective view of the container of FIG. 4 .

FIG6 is a perspective view of a membrane box assembly.

FIG. 7 is another perspective view of the bellows assembly of FIG. 6 .

8 is a perspective view of the membrane stack of the membrane cassette assembly of FIG. 6 .

9 is a side perspective view of the membrane stack of FIG. 8 .

FIG. 10 is an exploded view of a portion of the membrane stack of FIG. 8 .

11 is a detail view of a portion of the membrane stack of FIG. 8 illustrating the arrangement of the trays, permeate carriers, and membranes.

FIG12 is a partial cross-sectional view taken along line 12-12 of FIG9.

13 is a perspective view of a cross-flow membrane subsystem with a membrane cassette assembly inserted into a container.

FIG. 14 is a cross-sectional view taken along line 14 - 14 of FIG. 3 .

FIG15 is a perspective view of another bellows assembly.

FIG. 16 is a cross-sectional view taken along line 16 - 16 of FIG. 15 .

17 is a schematic diagram of an operating feed chute sequence for the processing system of FIG. 1 .

18 is a schematic diagram of an operational pressurization sequence for the processing system of FIG. 1 .

FIG19 is a schematic diagram of an operation flow adjustment sequence of the processing system of FIG1.

FIG. 20 is a schematic diagram of an operation driving sequence of the processing system of FIG. 1 .

21 is a schematic diagram of an operating alkaline CIP sequence of the treatment system of FIG. 1 .

22 is a schematic diagram of an operating acid CIP train of the treatment system of FIG. 1 .

Before describing any embodiments of the present invention in detail, it should be understood that the present invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The present invention is capable of other embodiments and can be practiced or carried out in various ways. Furthermore, it should be understood that the phraseology and terminology used herein are for descriptive purposes only and should not be construed as limiting.

DETAILED DESCRIPTION

FIG1 is a schematic diagram of a cross-flow dynamic membrane treatment system 10 having a high-speed cross-flow membrane subsystem 100. System 10 also includes: a support system 120 having a feed valve 122, a feed tank 124, and a feed pump 128; a chemical supply system 130 including a base chemical pump 131A and an acid chemical pump 131B; a retentate system 132; and a permeate collection system 134 including a permeate tank 140 for storing permeate for subsequent final use and, in some embodiments, a permeate transfer pump (not shown). Feed tank 124 may include a liquid level sensor 150, a temperature sensor 152, and a pH sensor 154, a mixer 156, and a heater 158. Other fluid transfer components (such as transfer and recirculation pumps) along with associated piping, valves, and metering devices may be included in system 10, but need not be described in detail. The support system 120 may include a local control panel (not shown) or a remote control panel (see FIG1 ) that communicates with the electrical and electronic components of the membrane subsystem 100 and the components of the system 10. The control panel houses the electrical panel and further includes, among other things, a programmable logic controller (PLC), a motor starter, a variable frequency drive (VFD), and a user interface (e.g., a touch screen HMI (human-machine interface) and/or manual switches, knobs, and indicator lights).

2 and 3 , the high-speed cross-flow membrane subsystem 100 includes a pressure vessel 200 supported by a mobile support frame 204, which is itself supported by wheels or casters 208. A drive in the form of a motor 220 is fixedly attached to the support frame 204, controlled by a control panel and VFD, and operatively connected to a drive belt 224 defined within a belt guard 228. In other embodiments, a pneumatic or hydraulic drive may be used in place of the electric drive.

4 and 5 , the pressure vessel 200 provides a sealed confined chamber, region, or volume 230 rated for operation of the membrane subsystem 100 at a positive gauge pressure and includes an end seal 240 and a hinged seal or door 244 having a plurality of door brackets 248 about a circumferential edge 252 configured to engage opposing pivot bolts 256 pivotally attached to a vessel body 260.

The orientation of the container 200 may be approximately horizontal, approximately vertical (relative to the ground surface), or at an angle for serviceability and to occupy the space available in a particular installation.

The pressure vessel 200 includes a feed port 270 for connecting to an inlet or feed conduit 274 and a drain port 280 for connecting to an outlet or concentrate conduit 284. The ports 270, 280 may be of any type known for use with such vessels, for example, in the form of straight or elbow flange connections, with or without additional tubing extending the port connections away from the vessel body 260.

In some embodiments, a single feed port 270 leads to a distribution header (not shown) that extends within the container 200 along a portion of the interior surface 290 and has multiple outlets. In the illustrated embodiment, a plurality of different feed ports 270 spaced along the length of the container 200 (from the first end to the second end, i.e., from the end cap 240 to the door 244, or vice versa) are instead utilized. The feed ports 270 are each connected to an inlet control valve 294, and each inlet valve 294 is in fluid communication with an inlet manifold 298 and a feed line safety valve 302 having an additional conduit connector (e.g., a "quick" conduit connector 310). The other side of the illustrated manifold 298 ends in a subsystem inlet port 314. A vent 324 at the apex of the container's curvature (depending on its orientation) includes a manual or automatic valve 328 that connects the interior of the container 200 to the outside air.

One or more of the feed ports 270 can also serve as CIP ports for clean-in-place (CIP) connections. For example, the entirety of the previously described inlet manifold 298 and inlet ports 270 can double as a CIP connection. Alternatively, in embodiments without an illustrated inlet manifold 298, one or more of the various feed ports 270 can alternatively serve as individual CIP ports (e.g., the center feed port 270), while retaining the side feed ports 270 for inlet feed liquid. A compressed air connection 320 with an air inlet valve 322 is provided along with the CIP connection, the purpose of which will be described in detail below.

In some embodiments, a single exhaust port 280 exits the container 200. In the illustrated embodiment, a plurality of different exhaust ports 280 spaced along the length of the container 200 and supported by the support frame 204 are each connected to an outlet control valve 330 via a concentrate outlet 284, each of which is in fluid communication with an outlet manifold 334 and an outlet port 338 of the subsystem 100.

A plurality of monitoring ports (eg, viewing ports 340, 344) are positioned along the exterior surface of the container body 260. Additional auxiliary ports may be present, including vertically spaced ports for use with a visual level indicator or level transmitter 350 and optionally a pressure transmitter 354.

The end seal 240 of the container 200 includes an inner flange 356 ( FIG. 5 ) and an outer flange 358. Referring also to FIG. 14 , a drive subassembly 360 includes a drive support shaft 364 that at least partially defines an opening 368 within the container interior that is concentric with the flange 356. The drive subassembly 360 cooperates with the drive belt 224 via a drive sheave 370 and further includes a bearing and a seal base (e.g., a lip seal) 374 ( FIG. 14 ) that penetrates the end seal 240 when assembled.

A permeate subassembly 380, including a flange 382 and a permeate conduit segment 384 having a permeate drain valve 386 (a ball valve, a butterfly valve, etc.), ends in a permeate port 388. As will be described further below, the permeate subassembly 380 covers a locking nut 390 at the end of the support shaft 364 and can be connected to the external flange 358.

Any of the inlet port 314 , outlet port 338 , or permeate port 388 may be in communication with additional pressure and/or flow transmitters for monitoring and system adjustments.

Within the interior of the vessel 200, an open manifold or trough 394 can be secured to the inner wall 290 of the vessel 200 to evenly distribute the feed flow from one or more of the feed ports and/or CIP ports 270. Specifically, the trough 394 can extend longitudinally adjacent to the entirety of the feed ports and CIP ports 270. Alternatively, the trough 394 can be positioned adjacent only some of the feed ports and CIP ports 270. Regardless of the positioning, the trough 394 comprises a defined volume that is arcuately or otherwise formed with a shaped edge 397 (e.g., a sawtooth shape, along all or a portion of the length of the trough 394).

The interior of the container body 260 further presents a plurality of interior mounting rails 396 that are fixedly attached to the interior surface 290 and positioned to receive the capsule assembly 400. In the illustrated embodiment, four interior mounting rails 396 are positioned approximately 90 degrees apart and are welded or otherwise permanently attached to the circular interior 290. Each rail 396 includes a 90-degree bend and can be, for example, a segment of angle iron with spaced-apart support plates 398 for welding. In other embodiments, one, two, three, or five or more mounting rails 396 can be attached and positioned around the interior 290.

As described further below, the opening 368 is cooperatively aligned with the internal mounting track 396 for insertion of the capsule assembly 400 .

6 , a film cartridge assembly 400 includes a plurality of film subassemblies or stacks 410 positioned within a frame 420 constructed from a plurality of insertion rails 424. The insertion rails 424 are formed for positional engagement with the internal mounting rails 396. The insertion rails 424 extend between opposing end frame members 430, 434, and additional support structures 440 may also provide structural stability to the frame 420. In an alternative embodiment of FIG15 , a centering plate or baffle 444 also extends between the end frame members 430, 440 and, as shown in FIG16 , at least partially extends into the space formed between the film stacks 410. The baffles 444 may be positioned between the film stacks 410 on one or both sides (i.e., two baffles 444 are shown in FIG16 ). In still other embodiments, one or more baffles 444 are instead attached to the container body 260, and more specifically project radially inward from the inner surface 290 of the container 200 within the chamber 230, such that the baffles 444 extend at least partially into the space formed between the two membrane stacks 410 when positioned within the container 200. In some embodiments, the aforementioned manifold or trough 394 may be mounted or otherwise secured to the membrane cartridge assembly 400, for example, on top of the assembly 400.

One or more radial baffles 446 may be removably or fixedly mounted above and/or below the cartridge assembly 400 and mounted to the cartridge frame 420. The baffles 446 are positioned to at least partially block the open space between the outer periphery of the disc and the inner surface 290 of the container 200 at the top and/or bottom ends of the cartridge assembly 400 (described in further detail below). The baffles 446 may be equally or unequally spaced along the length of the frame 420. In some embodiments, the baffles 446 may be axially offset from one another or tilted to one side or the other relative to the top and/or bottom of the cartridge assembly 400, respectively. In yet other embodiments, one or more baffles may be used, any one or all of which may be placed at any point along the frame or within the container 200. In some applications, the number and location of the baffles 446 depends on the length to diameter ratio of the stack 410 length to the diameter of the disc 500.

The frame 420 includes a manipulation handle 450 and connector assemblies 460, 464 at each end frame member. The first of the connector assemblies 460 presents a support bearing 470 concentric with a flange 474. The second connector assembly 464 on the other side of the frame 420 includes a support bearing 480 concentric with two capping flanges 484. In the illustrative embodiment described below, the number of membrane stacks 410 within the membrane cartridge assembly 400 is two, but one or three or more membrane stacks 410 may also be used with an appropriately configured frame 420, wherein the container 200 is adapted to receive three or more membrane stacks 410.

In some embodiments, a wheel box carrier (not shown) is configured to support and transport the membrane box assembly 400 and may include receiving rails to support two or more of the insertion rails 424 of the frame 420, but other methods of transporting one or more membrane assemblies 400 to the pressure vessel 200 are also contemplated.

As shown in Figures 8 and 9, each membrane stack 410 includes a series of axially spaced membrane-covered disks ("membrane disks") 500 with hubs 510 therebetween. Referring also to Figure 10, each disk 514 is sandwiched by opposing permeate carriers 518. The opposing outwardly facing side 522 of each permeate carrier 518 abuts a filtration membrane 530. The membrane 530 can be a reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), or microfiltration (MF) membrane.

Referring also to FIG11 , each disk 514 is constructed of a rigid, substantially non-porous plastic, ceramic, metal, biologically based (e.g., biological tissue), or similar material, extending radially and terminating in opposing peripheral lips 544 and peripheral edges 546, with the permeate carrier 518 and membrane 530 positioned so that the membrane 530 is approximately flush with the outer surface 548 of the peripheral lip 544. In other configurations, end caps (not shown) may be affixed to the periphery of the disk 514 to form a recess in which the permeate carrier 518 and membrane 514 are flushly positioned. In another embodiment, end caps may be formed on the outer edge of the disk 514 to encapsulate the membrane 530 and carrier 518. In yet other embodiments, the permeate carrier is not present, and the disk 514 is porous or semi-porous in construction and in direct contact with the surface of the membrane 530. Alternatively, the disks 514 may be constructed of sintered metal, metal plates, ceramics, or optionally, biologically based materials. Each tray contains a plurality of permeate collection holes 550 .

Referring to FIG10 , as mentioned, a hub 510 is located between each disk/membrane assembly 500, with a gasket 554 separating each hub 510 from the surface of the adjacent membrane 530. As will be described further below, the hub 510 and gasket 554 are formed with corresponding holes 558, 560 positioned to accommodate permeate flow, with the gasket 554 sealing the holes 558, 560 to confine the permeate flow. The disks 514, permeate carrier 518, membrane 530, hub 510, and gasket 554 are all coaxially aligned about a central shaft 570 having a longitudinal axis 572 and thereby form a disk spacing, i.e., an axial center-to-center disk distance D ( FIG9 ), which can vary from 0.125 inches or less to 2.0 inches or more, with a preferred spacing of 0.25 inches. In some industrial applications, the disks 514 can vary in radial size to optimize the available surface area in a particular system, and the disk diameter can vary from approximately 4 inches or less to up to 6 feet or more. Furthermore, the hub assembly dimensions can be varied for different spacings D between the disks 514. Furthermore, each end of the membrane stack 410 can include a plate or flywheel 580 that adequately distributes the weight. In some applications, such a plate 580 can be positioned within the membrane stack 410 itself, in addition to or in lieu of the illustrated end locations.

The disk 514, hub 510, and spacers 554 are assembled layer by layer on the shaft 570. At the permeate discharge end (corresponding to the end of the first connector assembly 460 of the frame 420), a plurality of conduits 590 (each associated with a corresponding alignment of holes 550, 558, 560) each form a bend connecting the end hub 510 to the permeate collection assembly 600 including a permeate tube 610, which is stepped or otherwise configured to mate with the drive support shaft 364 and support bearing 470. At the barrier end (corresponding to the end of the second connector assembly 464 of the frame 420), a threaded clamp 620 is used to compress the membrane disk 500 with the spacers 554 and hub 510 to form a plurality of longitudinal permeate channels 630 defined by and aligned with the holes 550, 558, 560 and having a disk spacing D that will be fluid-tight relative to the remainder of the contents of the vessel 200 during operation. The entire membrane stack 410 is held by compression applied by the threaded clamp 620 .

Each membrane stack 410 is then mounted to the frame 420 and rotatably coupled to the support bearings 470. Specifically, as shown in Figures 6, 7, and 16, the membrane stacks 410 are positioned within the frame 420 such that the disks 500 overlap, forming an overlap region 640 in which the disks 500 of one membrane stack 410 are interspersed within the disk spacing D of the other membrane stack 410, and vice versa. The radial distance of the overlap region 640 can vary, and in some applications, the gap between adjacent disks is approximately 0.25 inches from surface to surface. In other embodiments, the disks 500 of one membrane stack 410 do not overlap at all with the disks 500 of the other membrane stack 410. The second connector assembly 464 is then capped. To facilitate assembly, the baffles 444 can alternatively be removably coupled to the frame 420, such that one or both are attached to the frame 420 after the membrane stacks 410 are positioned within the frame 420. The assembled capsule assembly 400 may then be placed on a capsule carrier for shipping.

To assemble the complete high-speed cross-flow membrane subsystem 100, the membrane cassette assembly 400 must first be inserted into the container 200. To insert the membrane cassette assembly 400 into the container, the operator transports the cassette assembly 400 to the container 200 and aligns the insertion tracks 424 (four in the presently described embodiment) of the frame 420 with the mounting tracks 396 along the inner surface 290 of the container body 260. The operator then pushes the cassette assembly 400 into the container 200 along the length of the mounting tracks 396, which automatically aligns the permeate tube 610 with the opening 368. The permeate tube 610 passes through the end sealer 240 of the container 200, including the corresponding drive support shaft 364, the associated bearing and seal base 374, and the drive sheave 370. Next, the locking nut 390 for each permeate tube 610 is tightened, which secures the permeate tube to the drive support shaft 364. Flange 382, including conduit segment 384 and valve 386, is secured to the corresponding external flange 358. Other configurations of sealing and locking components for drive subassembly 360, such as drive bearing and non-drive bearing lip seals, or other shaft seals, may be operably positioned between permeate tube 610 and end cap 240 or optionally configured with permeate subassembly 380. In all embodiments, membrane subassembly 400 is secured within container 200 from the exterior thereof.

The inner rails 396 support the capsule assembly 400 during insertion. In some embodiments, the aforementioned baffles 446 instead comprise baffle inserts that can be positioned within the container 200 after insertion of the capsule assembly 400. In still other embodiments, one or more baffles can be removably or fixedly secured to the inner surface 290 prior to insertion of the capsule assembly 400.

Thereafter, the operator closes hinged door 244 to establish a watertight enclosure.With membrane cartridge assembly 400 in place and permeate tube 610 in communication with permeate subassembly 380, membrane system 100 may be operated.

In operation, the liquid level of the feed trough 124 is first determined and monitored by the liquid level sensor 150. Referring to Figures 1 and 17, if the liquid level sensor "low" state has not been sensed (step 1010), the feed valve 122 is opened to allow the feed flow to enter the trough 124 (step 1018). If at least the "low" state is sensed, the mixer 156 in the trough 124 is started (step 1014). Once the mixer 156 is activated, if the liquid level sensor "high" state (step 1030) is determined, the feed valve 122 is closed (step 1034), otherwise the feed valve 122 remains open (step 1038). At the same time, the temperature sensor 152 monitors the temperature of the contents of the trough 124 (step 1050) and turns on (step 1054) or turns off (step 1058) the heater 158 to adjust the feed temperature relative to the temperature set point.

The feed pH is also adjusted within the tank 124. With the mixer 156 turned on, the pH sensor 154 determines the pH of the feed relative to the pH set point (step 1060). If the sensed pH is less than the pH set point but not greater than the pH set point minus the offset factor or value (step 1064), the alkaline chemical pump 131A is activated (step 1068). If the sensed pH is greater than the pH set point minus the offset factor, the alkaline pump 131A is deactivated (step 1072). Similarly, if the sensed pH is greater than the pH set point but not less than the pH set point plus the offset factor (step 1080), the acidic chemical pump 131B is activated (step 1084). If the sensed pH is less than the pH set point plus the offset factor, the acidic chemical pump 131B is deactivated (step 1088).

Referring to Figure 18, once the aforementioned feeding parameters are determined and the liquid level sensor "high" state is satisfied (step 1110) and the liquid level sensor "low" state is operational or true (step 1114), the feed pump 128 is activated (if the liquid level sensor "low" state is false, then the feed pump 128 is deactivated (step 1118)).

According to the program of the PLC, the liquid to be treated is fed through the inlet port 314, through the manifold 298 and the open inlet control valve 294, and into the pressure vessel 200 via one or more feed ports 270 to distribute the liquid over some or all of the length of the installed membrane stack 410 within the pressure vessel 200. In the presence of the slot 394, the feed will fill the defined volume and spread over the edge 397. During this inflow of liquid, air within the vessel 200 is purged through the vent hole 324.

The use of specific feed ports 270 and drain ports 280 may depend on the application. In some applications, for example, the feed port 270 closer to one of the end seals 240 and hinged door 244 may be opened for feed inflow (with the other feed ports 270 closed), while the axially opposite drain port 280 (i.e., longitudinally with respect to the vessel 200 or perpendicular to the vessel diameter) is opened for concentrate discharge (with the other drain ports 280 closed) to increase the degree of axial flow of the medium to be processed within the vessel 200. This configuration can maximize the combined average flux rate across all membranes 530 in the membrane stack 410. In other applications, the center feed port 270 (of the three) is opened for feed flow, while all three drain ports 280 are open. Any combination of feed ports 270 and drain ports 280 may be opened or closed depending on the medium to be processed, the membranes 530 used, the desired rotational speed of the disc 500, the desired permeate flux or flow rate, or other considerations.

The pressure within the vessel 200 is monitored, and if it is equal to a predetermined set point pressure (step 1130) and greater than a minimum set point pressure (step 1134), the system is set to an "on" state (step 1140). The system is controlled to maintain the set point pressures: if the pressure within the vessel 200 is less than the set point pressure (step 1144), the speed of the pump 128 is increased via the VFD (step 1148); if the pressure within the vessel 200 is greater than the set point pressure, the speed of the pump 128 is decreased via the VFD (step 1152). If the vessel pressure drops below the minimum set point pressure, the system is no longer in the "on" state (step 1160).

With the system status "on" (step 1170), the drive 220 is simultaneously activated and the membrane stacks 410 are rotated at the desired rotational rate via the belt drive 224. The stacks 410 and belt 224 are configured so that the belt 224 rotates each stack 410 in the same direction within the container 200. The plate 580 provides a ballast or "flywheel" effect to the rotating membrane stacks 410. Referring also to FIG19, concentrate discharge is initially closed by valve 330 and/or valve 700 (see FIG1) downstream of the manifold 334, unless the system status is "on" (step 1172). The concentrate flow from the container is adjusted to maintain a predetermined VCF (volume concentration factor). Specifically, at step 1174, a desired concentrate flow rate is calculated based on the measured flow rate into the container 200 and the VCF. If the measured concentrate flow equals the desired flow rate (step 1178), the concentrate flow rate from the container 200 is maintained. If they are not equal (step 1182) and the measured concentrate flow rate is less than the desired flow rate, valve 700 in communication with the PLC can be actuated to increase the concentrate flow (step 1190). If the measured concentrate flow rate is greater than the desired flow rate, valve 700 can be actuated to decrease the concentrate flow (step 1194). Valve 700 can also be used to modulate the volumetric concentration factor of this flow. In some applications, valve 330 can control or modulate the concentrate flow from container 200 in addition to or in place of valve 700.

Once the container 200 is filled with liquid and pressurized to the appropriate operating pressure, the container pressure is automatically maintained by control of the concentrate discharge valve 330 and/or valve 700 as previously described and/or by VFD control of the feed pump 128 .

After rotating the film stack 410, a rotating or swirling flow of the contained liquid is generated around the inner surface 290 of the container 200, which may tend to stratify at least a portion of the fluid. This stratification hinders complete mixing of the fluid in the space between adjacent disks 500. The baffle or baffles 444 interrupt the swirling flow and divert or redirect more of the fluid into the overlapping disk spacing D to enhance mixing. The baffle 446 is used to minimize axial mixing or circulation of the fluid within the container 200 during operation.

As the pressure in the pressure vessel 200 increases, transmembrane pressure builds up across the membrane 530 (between the liquid on the exposed side of the membrane 530 and the permeate carrier side of the membrane 530) and drives liquid through the membrane 530 of each disc 500. The membrane separates particulates and dissolved substances (both inorganic and organic) from the liquid passing through the membrane 530, depending on the specific properties of the membrane 530. The filtered liquid, in the form of permeate, enters the permeate carrier 518 and flows radially toward one of the permeate channels 630 formed by the holes 550, 558, 560, where it is collected. The permeate is at a pressure sufficient to allow it to be transported axially along the length of the central axis 570 to the permeate subassembly 380. In those embodiments having a porous disc 514, the permeate flows radially through the porous disc into the openings in the disc and through one of the channels 630.

During this process, due to the rotational direction of each disk 500 of each membrane stack 410, the surface of one disk 500 is 'close' to the surface of the other immediately adjacent disks 500 of the other membrane stacks 410 within the overlapping disk spacing D. The liquid at the surface of the membranes 530 that has not passed through the membranes 530 contains retained solids, which are held in suspension by the high velocities induced by this relative disk rotation. The liquid that has not passed through the membranes 530 and contains these solids continues through the vessel 200 to the concentrate discharge port 280 and through the vessel 200 to the outlet port 338 as concentrate, where it can be recycled for additional passage through the vessel 200 (through additional conduits connected to the feed water) or otherwise discharged (for example) to a drain or to the retentate system 132. General regulation of the concentrate flow was previously described. Concentrate is continuously collected from the vessel 200 and, in some embodiments, passes through an additional backpressure flow control valve to maintain pressure within the interior of the pressure vessel 200 and/or maintain a predetermined solids concentration.

Once at the desired operating pressure, the system 100 can operate continuously, subject to automatic control of permeate flow, vessel pressure, disk rotation speed, rotation direction, concentrate discharge rate, and feed supply rate. As an example, the disk rotation speed can be set to achieve a desired number of revolutions per minute (rpm) to achieve the necessary crossflow rate in combination with a sufficient permeate flow rate. The flux rate through the membrane 530 can also be identified in real time, either by the transmitted permeate flow rate or by the difference between the flow rate through the inlet port 314 and the flow rate leaving the outlet port 338. The drive rpm can then be adjusted as necessary to obtain the desired permeate flow rate. Referring to FIG. 20 , at the appropriate pressure (otherwise the drive 220 stops rotating the membrane stack 410, step 1198), the permeate flux rate is calculated based on the difference between the feed flow and the concentrate flow (step 1200). If the flux rate corresponds to a predetermined flux set point (step 1204), the system continues its current operation.

The rotational speed of the chopper wheel 500 is adjusted to maintain the permeate flux rate. Specifically, if the flux rate is greater than the set point at step 1210, the VFD-operated driver 220 is reduced (step 1214), thereby reducing the rotational speed of the membrane stack 410. If the flux rate is less than the set point at step 1210, the rotational speed of the driver 220 is compared to a maximum rotational speed (step 1220); if the maximum is not exceeded, the rotational speed of the driver 220 is increased (step 1224).

If the maximum rotational speed is exceeded, the motor control sequence is initiated. Using this control sequence, a counter is incremented (step 1230) and the "ramp-up" count is compared with the ramp-up maximum value (step 1234). If it is not greater than the ramp-up maximum value, a ramp-up cleaning cycle is initiated (step 1240), wherein the rotational speed of the disc 500 is significantly increased to increase the speed across the membrane surface. Therefore, if the permeate flux rate decreases over time, the driver 220 rpm can be temporarily increased to increase the relative speed between the two membrane surfaces, thereby producing an enhanced "self-cleaning" effect. As the permeate flux rate increases thereafter, the driver 220 rpm can be adjusted to reduce it if necessary. If the ramp-up count is greater than the maximum value, an alarm is activated (step 1244), a reverse counter is incremented (step 1248), and the reverse counter is compared with the reverse maximum value (step 1254). If the reverse counter value is not greater than the reverse maximum value, the direction of the driver 220 is reversed within a predetermined time before the ramp-up cleaning cycle (in the reverse direction) (step 1260). If it is greater than the reverse maximum, then operation stops and the system is shut down (step 1264) for cleaning.

In general, disk rotation can be intermittent or periodically cycled to reduce energy consumption during operation while still maintaining sufficient membrane cross-flow. In some embodiments, as described, the disk stack 410 can be periodically reversed in the direction of rotation. Control of the concentrate flow rate through the concentrate control valve 330 or valve 700 as previously described occurs simultaneously with the permeate flux rate calculation to allow the system 100 to concentrate the solids in the concentrate to a desired level.

Thus, a membrane filter can be used to separate solids from liquids using reduced energy by rotating the membrane surface within the liquid relative to the high-speed pumping of the liquid across the membrane surface. A higher cross-flow rate results in a higher operating flux through the membrane 530 and reduced membrane clogging. The interspersing of the rotating disks 500 on the parallel shafts 570 results in an even flow rate and distribution across the membrane surface.

Periodically and/or in response to a reduced permeate flow rate at a given pressure during operation, system 100 is shut down for short periods to chemically clean membrane 530 (CIP or clean-in-place). This can be accomplished by feeding low-pH (acidic) and/or high-pH (alkaline) chemical and/or detergent solutions at a preferred temperature through chemical system 120 to vessel 200 and recirculating them through feed/recirculation tank 124 over a predetermined period. Thereafter, as determined by the recovery flux at a given pressure, system 100 is purged of the chemical solution and returned to operation after sufficient cleaning. Alternatively, a specific amount of chemical solution is introduced into vessel 200 through a designated CIP feed connection. The CIP solution is dispensed onto the surface of membrane 530 via tank 394. Significantly, the vessel is not filled to capacity during the CIP process. Instead, a smaller amount of CIP solution is dispensed. Then, disk 500 is rotated to further distribute the CIP solution over the membrane surface area. Compressed air is injected into the vessel 200 through the compressed air injection port 320 to provide pressure and further force the CIP solution through the membrane.

Referring to FIG. 21 , a specific alkaline CIP process is described. Starting with a level sensor 150 in tank 124 (step 1310), with the level sensor in a "high" state, feed valve 122 is closed (step 1318) and mixer 156 is activated (step 1324). If the level sensor "high" state is not met, feed valve 122 is opened to fill tank 124 (step 1326). Temperature sensor 152 monitors the contents of tank 124 (step 1330) and turns heater 158 on (step 1334) or off (step 1338) to adjust the feed temperature relative to the CIP temperature set point (e.g., approximately 120°F).

The pH of the tank contents is compared to the CIP alkaline set point (e.g., approximately pH 12) (step 1342) and if not greater than the set point, the alkaline chemical pump 131A is activated (1346); if greater than the set point, the alkaline pump 131A is deactivated (step 1350).

The liquid level in container 200 is determined from liquid level transmitter 350. If neither the "high" level (step 1360) nor the "low" level (step 1364) is triggered, feed pump 128 is activated (step 1368). As the solution level in container 200 rises, feed pump 128 continues to provide CIP solution from tank 124 until the "high" level is reached, at which point feed pump 128 is deactivated (step 1374). The "high" and "low" levels are positioned relative to the interior of the container so that the "high" level can be significantly less than half, one-quarter, or even less than the total volume of container 200. In this particular application, the CIP process uses a minimal amount of solution; for example, a 10,000-gallon container can be cleaned using this process using only 50 to 100 gallons of CIP solution.

At the same time, the pressure inside the vessel 200 is maintained by using compressed air. Specifically, the pressure inside the vessel 200 is monitored (step 1380), and if it is less than the CIP setpoint pressure (step 1384), the inlet valve 322 is actuated or opened to allow compressed air to flow into the vessel 200 (step 1390). If the vessel pressure is greater than the CIP setpoint pressure, the inlet valve 322 is closed (step 1394). Once the pressure is greater than the CIP setpoint (step 1400), the driver 220 is activated to rotate the disk 500 for a predetermined time (step 1410), after which the CIP sequence is completed (step 1420). Once completed (step 1430), the inlet valve 322 is closed (step 1440) and the feed pump 128 is deactivated (step 1450).

Referring to FIG22 , a specific acid CIP process is illustrated, wherein similar steps share similar numbering with the aforementioned alkaline CIP process illustrated in FIG21 . Tank 124 liquid level sensor 150 and temperature sensor 152 operate as previously described, the pH of the tank contents is compared to the CIP acid set point (e.g., approximately pH 2) (step 1542 ), and if not greater than the set point, the acid chemical pump 131B is activated ( 1546 ); if greater than the set point, the acid pump 131B is deactivated (step 1550 ). The remainder of the acid CIP process is as previously described for the alkaline CIP process.

A membrane cartridge 400 that has exceeded its useful life can be removed from the container 200 and replaced with another membrane cartridge. Specifically, a membrane cartridge 400 removed from the container 200 can be shipped, transported, or otherwise delivered to a local or remote facility and cleaned, or alternatively some or all of the membranes 530, permeate carriers 518, or discs 514 can be replaced, re-encapsulated, and shipped back to the same system or to another system in another location.

To remove the membrane cartridge assembly 400 from the container 200, the operator essentially reverses the previously described operations. The flange 382 (with the conduit section 384 and valve 386) is loosened and removed from the outer flange 358, exposing the locking nut 390. By loosening the locking nut 390, the permeate tube 610 of each assembly 400 is no longer engaged with the drive support shaft 364. The operator pulls the cartridge assembly 400 away from the container 200 along the mounting rail 396. A new or cleaned cartridge assembly 400 can then be inserted as previously described.

In certain embodiments, the system 10 may be used for water treatment, wastewater treatment, seawater treatment, landfill leachate, frac water, purification of sweeteners, product recovery, chemical and solvent purification, catalyst recovery, oil/water separation, juice, wine and beer purification, pre-filtration for subsequent processes, and the like.

While the above describes example embodiments of the present invention, these descriptions should not be viewed in a limiting sense. Rather, several variations and modifications may be made without departing from the scope of the present invention.

Claims (18)

1. A high-speed cross-flow dynamic membrane filtration system, comprising: The disc membrane assembly includes frame, At least two support shafts, each defining a longitudinal axis, a plurality of axially spaced diaphragm disks positioned around the longitudinal axis, and each shaft further coupled to the frame. A permeate tube, which is coupled to each support shaft and is in fluid communication with the membrane disk associated with the support shaft; A container defining a processing chamber and configured to removably support the disc-film assembly within the processing chamber, the container further comprising walls; and Drive system The permeate tube is configured to extend through a portion of the container wall when the membrane assembly is positioned within the treatment chamber, and the permeate tube is further configured to rotate via the drive system. The frame includes first and second end members, and a plurality of tracks extend between the first and second end members, the tracks being oriented generally parallel to the permeate tube. The container further includes a plurality of mounting rails attached to the interior of the container, each mounting rail being configured to receive a rail of the frame. 2. The system of claim 1, wherein the at least two support shafts include a first support shaft and a second support shaft, and wherein a plurality of diaphragm discs associated with the first support shaft are distributed among a plurality of diaphragm discs associated with the second support shaft. 3. The system of claim 1, wherein the permeation tube is further configured to rotate clockwise and counterclockwise. 4. The system of claim 1, further comprising a plurality of hubs, each hub being positioned around one of the at least two support shafts between two adjacent disks of the plurality of axially spaced membrane disks, each of the plurality of hubs including at least one orifice in fluid communication with the permeate tube associated with the at least two support shafts. 5. The system of claim 4, wherein the plurality of hubs together at least partially define a permeate channel parallel to one of the at least two support shafts. 6. The system of claim 1, wherein each of the plurality of axially spaced membrane disks comprises a disk body constructed of a non-porous material. 7. The system of claim 2, wherein the frame includes a baffle that is at least partially positioned between the plurality of diaphragm discs associated with the first support shaft and the plurality of diaphragm discs associated with the second support shaft. 8. The system of claim 1, wherein the container comprises a plurality of inlet ports and a plurality of outlet ports, and wherein the system is configured to selectively allow access to the container by means of each feasible set or subset of the plurality of inlet ports combined with each feasible set or subset of the plurality of outlet ports. 9. The system of claim 8, wherein the plurality of inlet ports comprises three inlet ports, and wherein the plurality of outlet ports comprises three outlet ports. 10. The system of claim 9, wherein the container has a container diameter orthogonal to the container length, and wherein the three inlet ports are aligned longitudinally with the container, and wherein the three outlet ports are aligned longitudinally with the container. 11. The system of claim 2, further comprising at least one plate coupled to the container or the disc-film assembly when the disc-film assembly is positioned in the processing chamber, such that the at least one plate extends at least partially between the plurality of axially spaced film discs of the first support shaft and the plurality of axially spaced film discs of the second support shaft. 12. A method for operating a high-speed cross-flow dynamic membrane filtration system, the method comprising: Fluid flow is fed into a pressure vessel that defines a processing chamber for a disc-membrane assembly. The assembly has a first support shaft and a second support shaft, each support shaft defining a longitudinal axis. A plurality of axially spaced membrane discs are positioned around the longitudinal axis. The disc-membrane assembly also includes a frame, wherein the frame includes a first end member and a second end member, and wherein a plurality of tracks extend between the first end member and the second end member. The vessel further includes a plurality of mounting tracks attached to the interior of the vessel, each mounting track configured to receive a track of the frame. Distribute the fluid flow over at least a portion of the disc-diaphragm assembly; Discharge a first portion of the fluid flow from the container; Discharge a second portion of the fluid flow from the container; The first support shaft and the second support shaft are rotated in a first direction, the rotation comprising modulating the rotation rate in response to the flow rate of the second portion of the fluid flow. 13. The method of claim 12, wherein the container defines a length between a first end and a second end and includes a plurality of feed ports spaced apart along the length and a plurality of discharge ports spaced apart along the length, wherein distributing the fluid flow over at least a portion of the disc-film assembly includes distributing the fluid flow through a feed port that is closer to the first end than the second end, and wherein discharging the first portion of the fluid flow from the container includes discharging the first portion through a discharge port that is closer to the second end than the first end. 14. The method of claim 12, further comprising rotating the first support shaft and the second support shaft in a second direction opposite to the first direction in response to a flow parameter. 15. A disc-diaphragm assembly comprising: A frame, comprising first and second end members, wherein a plurality of tracks extend between the first end member and the second end member; and Supporting shaft member, which defines a longitudinal axis, with multiple axially spaced diaphragm disks positioned around the longitudinal axis, each diaphragm disk containing The disk body has a first surface and a corresponding second surface. A first permeate carrier in direct contact with the first surface, a second permeate carrier in direct contact with the second surface, a first filter membrane in direct contact with the first permeate carrier, and a second filter membrane in direct contact with the second permeate carrier. 16. The disc membrane assembly of claim 15, wherein the first and second filter membranes are porous membranes. 17. The disc-film assembly of claim 15, wherein the disc body is a non-porous disc body. 18. The disc-film assembly of claim 15, wherein the disc body further includes a peripheral lip adjacent to an outer edge, and wherein the first permeate carrier and the first filter element are positioned such that the first filter element is substantially flush with the outer surface of the peripheral lip.