EA040270B1 - DESIGN OF HYDRAULIC MANIFOLDS IN ELECTRODIALYSIS DEVICES - Google Patents

Description

Related Applications

This patent application claims priority under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62/522,732 entitled Design of Hydraulic Manifolds in Electrodialysis Devices and filed June 21, 2017, the contents of which are incorporated in their entirety in this application by reference.

The field of technology to which the invention belongs

Aspects and embodiments disclosed herein generally relate to electrochemical membrane systems and their method of operation.

State of the art

Devices for cleaning fluids using electric fields can be used to treat water and other liquids containing dissolved ionic forms (particles). Two types of devices that treat water in this way are devices for electrodeionization and electrodialysis. Inside these devices are concentration and dilution chambers separated by ion-selective membranes. An electrodialysis device typically includes alternating electroactive semi-permeable anion and cation exchange membranes. The spaces between the membranes are configured to create liquid flow chambers with inlets and outlets. An external electric field applied by the electrodes causes the formation of dissolved ions, which are attracted to the corresponding counter electrodes and migrate through the anion and cation exchange membranes. This generally results in the liquid in the dilution chamber becoming depleted of ions and the liquid in the concentration chamber enriched in carried ions.

Devices similar in design to electrodialysis devices can be used as reverse electrodialysis (ROD) devices. The two sets of chambers are fed with fluids with different concentrations of ions separated by ion selective membranes, such as sea water and river water. The difference in concentrations and chemical potentials leads to the appearance of a voltage difference on each membrane, which, when summed over the entire number of membranes in the device, leads to a potential generated on two electrodes that limit the package of chambers and membranes.

Disclosure of invention

In accordance with one or more aspects, the electrochemical separation system may include a first electrode, a second electrode, a first modular electrochemical separation unit having a first cell stack forming a plurality of alternating depletion chambers and concentrating chambers supported by a first frame, wherein the first modular electrochemical separation unit is located between the first electrode and the second electrode and a second modular electrochemical separation unit adjacent to and cooperating with the first modular electrochemical separation unit having a second cell stack forming a plurality of alternating depletion chambers and concentrating chambers supported by the second frame, wherein the second modular electrochemical separation unit is located between the first modular electrochemical separation unit and the second electrode.

In accordance with one or more aspects, a method for assembling an electrochemical separation system may include mounting a first modular electrochemical separation unit having a first cell stack surrounded by a first frame in a vessel between the first electrode and the second electrode, and mounting a second modular electrochemical separation unit having a second cell stack, surrounded by a second frame, in a vessel between the first modular electrochemical separation unit and the second electrode.

In accordance with one or more aspects, a modular electrochemical separation unit may include a cell stack defining a plurality of alternating depletion chambers and concentrating chambers, and a frame surrounding the cell stack and including a manifold system configured to allow fluid to flow through the cell stack.

In accordance with one or more aspects, the electrochemical separation flow distributor may comprise a plurality of first passages (channels) oriented in a first direction and configured to deliver feed material to at least one chamber of the electrochemical separation device, and a plurality of second passages oriented in a second direction. direction, wherein the plurality of second passages are in fluid communication with the plurality of first passages and with the intake manifold associated with the electrochemical separation device.

In accordance with one or more aspects, the electrochemical separation system may include a first electrode, a second electrode, a first modular electrochemical separation unit including a plurality of alternating depletion chambers and concentrating chambers located between the first and second electrodes, and a second modular electrochemical separation unit including a plurality of alternating depletion chambers and concentrating chambers, wherein the second modular electrochemical separation unit is designed to co-operate with the first modular electrochemical separation unit and is located between the first modular electrochemical separation unit and the second electrode, and a spacer placed between and next to the first and second modular blocks of electrochemical separation, made with the possibility of reducing current losses in the system.

In accordance with one or more embodiments, a modular electrochemical separation system, which may also be referred to as an electrical cleaning device or apparatus, can increase the efficiency or overall flexibility of various processing processes. In some embodiments, cross-flow electrochemical separation devices, such as cross-flow electrodialysis devices (ED devices), can be implemented as an attractive alternative to traditional frame devices. Crossflow devices are disclosed in US 8627560 B2, US 8741121 B2 and US 20160346737 A1, all of which are incorporated herein in their entirety in all respects by reference. In some embodiments, current inefficiencies in cross-current electrochemical separation devices can be reduced. In at least some embodiments, current inefficiency due to current bypassing through the intake and exhaust manifolds can be eliminated. Energy consumption and membrane requirements can also be reduced, both of which can affect lifetime costs in various applications. In some embodiments, at least 85% membrane utilization can be achieved. The reduction in membrane requirements may, in turn, lead to reductions in manufacturing cost, weight, and dimensional requirements for electrochemical separation devices.

In some specific embodiments, the process efficiency of cross-flow electrodialysis devices can be significantly improved. In some embodiments, the efficiency of electrochemical separation systems can be increased to provide desalination of hard water, sea water, and brines in oil and gas production. In at least some embodiments, the cost competitiveness of electrodialysis can be improved over reverse osmosis (RO), which is currently the leading desalination technology.

One or more embodiments disclosed herein relate to devices capable of electrically purifying fluids that may be contained within a housing, as well as methods of making and using them. The liquids or other fluids to be treated enter the treatment device and are processed under the influence of an electric field to obtain an ion-depleted fluid. Particles from incoming liquids are collected to obtain an ion-concentrated liquid.

According to one or more embodiments, the electrochemical separation system or apparatus may be modular. Each modular unit can typically function as a sub-unit of the overall electrochemical separation system. The modular block may include any desired number of pairs of cells. In some embodiments, the number of cell pairs per module may depend on the total number of cell pairs and passages in the separator. It may also depend on the number of pairs of cells that can be thermally bonded and sealed in a frame with an acceptable failure rate in cross-leak tests and other performance criteria. The quantity may be based on a statistical analysis of the manufacturing process and may be increased as the process control improves. In some non-limiting embodiments, a modular unit may include from about 50 to about 100 pairs of cells. Modular units can be individually assembled and subjected to quality control tests such as leakage, separation performance and pressure drop before being integrated into a larger system. In some embodiments, the cell stack may be installed in a frame as a modular unit that can be independently tested. A plurality of modular units may be assembled together to provide a total design number of cell pairs in an electrochemical separation device. In some embodiments, the assembly method may generally include placing a first modular block on a second modular block, placing a third modular block on the first and second modular blocks, and repeating to obtain a plurality of modular blocks in the desired number. In some embodiments, the assembly or individual modular units may be inserted into the pressure vessel for operation. Multiple flow configurations are possible by placing blocking membranes and/or spacers between the modular units or within the modular units. The modular principle can improve manufacturability in terms of time and cost savings. Modularity can also facilitate system maintenance by providing the ability to troubleshoot, isolate, remove, and replace individual modular units. Individual modular units may include manifold systems and flow distribution systems to aid in the electrochemical separation process. The individual modular units may be in fluid communication with each other, as well as with the central manifold and other systems associated with the overall process of electrochemical separation.

According to one or more embodiments, the efficiency of electrochemical separation systems can be improved. Current losses are one potential source of inefficiency. In some embodiments, such as those incorporating a cross-flow design, the possibility of current leakage can be eliminated. Current efficiency can be defined as the percentage of current that is efficient in moving ions from a dilute stream to a concentrated stream. There can be various sources of current inefficiency in an electrochemical separation system. One potential source of inefficiency may include current bypassing the cell pairs by dilute and concentrated flows through the intake and exhaust manifolds. The open intake and exhaust manifolds can be in direct fluid communication with the flow chambers and can reduce the pressure drop in each flow path. Part of the electric current from one electrode to another can bypass the stack of pairs of cells (shunt), flowing through the open zones. Bypass current (shunt current) reduces current efficiency and increases power consumption. Another potential source of inefficiency may include ions entering a dilute stream from a concentrated one due to the non-ideal selective permeability of ion exchange membranes. In some embodiments, techniques associated with sealing and potting membranes and shields within a device can help reduce current leakage.

In one or more embodiments, the bypass path through the stack can be manipulated to allow current to flow in a direct path through the cell stack to improve current efficiency. In some embodiments, the electrochemical separation device may be configured and positioned such that one or more detours are more tortuous than the direct path through the cell stack. In at least some embodiments, the electrochemical separation device may be configured and positioned such that one or more bypass paths present more resistance than a direct path through the cell stack. In some embodiments, including a modular system, individual modular units may be configured to improve current efficiency. The modular units may be designed and positioned to facilitate the formation of a current bypass that will contribute to current efficiency. In non-limiting embodiments, the modular unit may include a collector system and/or a flow distribution system configured to improve current efficiency. In at least some embodiments, a frame surrounding a cell stack in a modular electrochemical separation unit may be configured and positioned to facilitate the formation of a current bypass path. In some embodiments, providing a multi-pass flow configuration within an electrochemical separation device may help reduce current leakage. In at least some non-limiting embodiments, blocking membranes and/or spacers may be inserted between the modular units to direct dilute and/or concentrated flows in a multi-pass flow configuration to improve current efficiency. In some embodiments, a current efficiency of at least 60% can be achieved. In other embodiments, a current efficiency of at least 70% can be achieved. In still other embodiments, a current efficiency of at least 80% can be achieved. In at least some embodiments, a current efficiency of at least 85% can be achieved.

In accordance with one or more aspects, the electrochemical separation apparatus may comprise a stack of cells. The cell stack may further comprise a plurality of aligned cell pairs, wherein each of the plurality of aligned cell pairs includes an ion concentration chamber configured and positioned to provide fluid flow in a first direction and an ion depletion chamber. , configured and positioned to allow fluid to flow in a second direction different from the first direction.

According to one or more aspects, an electrochemical separation apparatus is provided. The electrochemical separation device comprises a first electrode, a second electrode, a cell stack including alternating depletion chambers and concentrating chambers located between the first electrode and the second electrode, an inlet manifold configured to introduce fluid into the depletion chambers or into the concentrating chambers, an exhaust manifold and one or more fluid flow guides disposed within the intake manifold and having a surface configured to change the flow path of the fluid introduced into the intake manifold and direct the fluid into the lean chambers or the concentrating chambers, and a second guide for fluid flow located inside the exhaust manifold and having a surface configured to change the flow path of the fluid introduced into the exhaust manifold through the depletion chambers or through the concentrating chambers.

In some embodiments, the fluid flow path through the depletion chambers is perpendicular to the fluid flow path through the concentration chambers.

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In some embodiments, the fluid flow guide is located within the intake manifold and configured to at least partially block shunt current through the intake manifold. The fluid flow guide may define a fluid flow path through the intake manifold between different portions of the cell stack having a cross-sectional area smaller than the intake manifold's cross-sectional area.

In some embodiments, the cell stack has an average current efficiency of at least 85%.

In some embodiments, the cell stack includes a plurality of subassemblies, and the fluid flow guide includes a plurality of ramps configured to direct fluid to various respective subassemblies of the plurality of subassemblies. A gap of less than 1 mm may be formed between the edges of each of the ramps and the cell stack.

In some embodiments, the fluid flow guide includes a plurality of channels that are fluidly isolated from each other. Each of the plurality of channels may terminate at a respective ramp of the plurality of ramps. The sum of the cross-sectional areas of the plurality of passages may be less than the cross-sectional area of the intake manifold.

In some embodiments, the device further comprises a second fluid flow guide located within the exhaust manifold. The second fluid flow guide may be configured to at least partially block shunt current through the exhaust manifold.

In some embodiments, the apparatus further comprises a second cell stack defining alternating second lean chambers and second concentrating chambers positioned between the cell stack and the second electrode, a second intake manifold aligned with the exhaust manifold and configured to introduce fluid from the exhaust manifold into the second depletion chambers or into the second concentrating chambers, a third fluid flow guiding device located inside the second intake manifold and having a surface configured to change the flow path of the fluid introduced into the second intake manifold and direct the fluid into the second depletion chambers or into second concentrating chambers, a second exhaust manifold located on the opposite side of the second cell stack relative to the second intake manifold, and a baffle separating the intake manifold from the second exhaust manifold in fluid e.

In some embodiments, the cell stack includes a plurality of subassemblies, and the fluid flow guide includes a plurality of baffles configured to isolate fluid flow to each of the plurality of subassemblies from fluid flow to the other of the plurality of subassemblies. The fluid flow guide may further include concentric fluid channels.

In some embodiments, the fluid flow guide includes a curved protrusion extending inwardly in the direction of the cell stack from the intake manifold wall. The fluid flow guide may reduce the cross-sectional area of the intake manifold by a first amount at an end of the intake manifold and by a second amount greater than the first amount at a midpoint along the length of the intake manifold. The fluid flow guide may be configured to reduce the rate of fluid flow through the chambers in the central region of the cell stack.

In some embodiments, the device further comprises a second fluid flow guide located within the exhaust manifold. The second fluid flow guide may have a cross-sectional area that decreases along the flow path through the exhaust manifold. The second fluid flow guiding device may be configured to reduce the pressure drop of the fluid through the device.

In some embodiments, the apparatus further comprises a fluid inlet having a different cross section than the intake manifold and a hydraulic adapter positioned between the fluid inlet and the intake manifold. The hydraulic adapter may include a conduit having a first inward cone section in which the cone width decreases along a first axis, and a second outward cone section in which the cone width increases along a second axis, wherein the first section and second section do not overlap. The inwardly directed cone of the first channel section may be an elliptical cone.

In some embodiments, the device further comprises a recirculation channel configured to direct the concentrate that has passed through the concentration chambers back to the concentration chambers.

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In some embodiments, the intake manifold is divided into fluid-isolated channels configured to direct predetermined amounts of fluid to different portions of the cell stack. The fluid insulated tubes may have cross-sectional areas chosen to cause the fluid flow rate through the chambers in the central region of the cell stack to be slower than the fluid flow rate through the chambers in the top and bottom regions of the cell stack. Fluid-isolated channels may have cross-sectional areas selected to cause the fluid flow rate through the chambers in the top region of the cell stack to be substantially equal to the fluid flow rate through the chambers in the lower region of the cell stack.

In accordance with one or more aspects, a method is provided for improving current efficiency in an electrochemical separation apparatus including a cell stack forming alternating depletion chambers and concentrating chambers located between a first electrode and a second electrode, wherein the fluid flow path through the depletion chambers is perpendicular to the path fluid flow through the concentrating chambers. The method includes installing a fluid flow guide in an apparatus intake manifold, the fluid flow guide having a surface configured to change the flow path of the fluid introduced into the intake manifold, directing the fluid into one of a plurality of depletion chambers or a plurality of concentrating chambers and at least partially blocking shunt current through the intake manifold.

In some embodiments, the method further includes improving the uniformity of fluid flow through the cell stack by installing a hydraulic adapter at the inlet of the intake manifold, wherein the hydraulic adapter includes a conduit having a first section with an inwardly directed cone in which the width of the conduit decreases along the first axis, and a second section with an outwardly directed cone in which the width of the channel increases along the second axis, while the first section and the second section do not overlap. The first axis may be perpendicular to the second axis.

In some embodiments, the method further includes reducing the pressure drop in the apparatus by providing a conical fluid flow guide in the apparatus outlet manifold.

In some embodiments, the method further includes installing a second fluid flow guide in the apparatus exhaust manifold, wherein the second fluid flow guide has a curved surface that narrows the flow path through the exhaust manifold by a first amount at a midpoint along the length exhaust manifold and a second amount less than the first amount near the end of the exhaust manifold.

According to one or more aspects, an electrochemical membrane device is provided. The electrochemical membrane device comprises a first electrode, a second electrode, a cell package including alternating depletion chambers and concentrating chambers located between the first electrode and the second electrode, ion-selective membranes separating the depletion chambers from the concentrating chambers, an inlet manifold configured to introduce fluid into the lean chambers or into the concentrating chambers, an exhaust manifold and one or more of a fluid flow guiding device located inside the intake manifold and having a surface configured to change the flow path of the fluid introduced into the intake manifold and direct the fluid to the lean chambers or concentrating chambers, and a second fluid flow guiding device located inside the exhaust manifold and having a surface configured to change the flow path of the fluid introduced into the exhaust manifold through the lean ne chambers or through concentrating chambers.

In some embodiments, the device is an electrodialysis device for purifying fluids using electric fields.

In some embodiments, the device is a reverse electrodialysis device for generating electricity from two or more fluid streams with different ion concentrations.

Also, other aspects, embodiments, and advantages of these illustrative aspects and embodiments are detailed below.

The embodiments disclosed herein may be combined with other embodiments in a manner consistent with at least one of the principles disclosed herein, with reference to an embodiment, some embodiments, an alternative embodiment, various embodiments, one embodiment implementation, etc. are not necessarily mutually exclusive and are intended to indicate that the particular feature, structure, or characteristic described may be included in at least one embodiment. Optionally, all such terms appearing in the text on

- 5 040270 of this document refer to the same embodiment.

Brief description of the drawings

The attached drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures is represented by the same reference numeral. For the sake of clarity, not every component may be labeled in every drawing.

In FIG. 1A shows an example subunit of an electrodialysis device.

In FIG. 1B shows a package of the four sub-units shown in FIG. 1A, before installation in the housing.

In FIG. 1C shows an assembled electrodialysis device with a transparent casing.

In FIG. 1D shows an assembled electrodialysis device with an opaque casing.

In FIG. 1E shows a computational fluid dynamic (CFD) model of an electrodialysis device with four subassemblies.

In FIG. 2A shows fluid being supplied to the dilution chambers of the electrodialysis device through an outer tube to a transition joint.

In FIG. 2B shows fluid being distributed to all dilution chambers of an electrodialysis device in parallel through an inlet manifold.

In FIG. 2C shows a single pass configuration of the electrodialysis device.

In FIG. 2D shows a two-pass configuration of the electrodialysis device.

In FIG. 3 depicts a non-ideal electrodialysis with inefficiency and water loss.

In FIG. 4 shows a simplified model for current flow in a dilution or concentric cell of an electrodialysis device.

In FIG. 5 is a network model of an electrical resistive circuit for simulating the flow of current in an electrodialysis device.

In FIG. 6 shows the calculation of the electrical resistance to shunt current for a triangular port design.

In FIG. 7 is a graph illustrating an example of the change in current efficiency depending on the location of a pair of cells in the passage.

In FIG. 8 is a graph illustrating an example of average current efficiency as a function of the number of cell pairs in a pass.

In FIG. 9 is a graph illustrating an example of average current efficiency as a function of dilute feed concentration and average concentration in concentrate/average concentration in dilute stream.

In FIG. 10A is a cross-sectional view of the basic design of an electrodialysis device.

In FIG. 10B depicts the results of CHD flow simulations in a package of four sub-blocks of the basic design shown in FIG. 10A.

In FIG. 10C is a graph illustrating vertical position versus flow rate through cell pairs in the basic design shown in FIG. 10A.

In FIG. 11A shows the results of CFD simulations of the flow in the topmost pair of cells in the basic design shown in FIG. 10A.

In FIG. 11B depicts the results of CFD simulations of the flow in the central pair of cells in the basic design shown in FIG. 10A.

In FIG. 11C depicts the results of CFD simulations of the flow in the lowest pair of cells in the basic design shown in FIG. 10A.

In FIG. 12A shows flow guiding elements for an electrodialysis device in the form of tubular channels.

In FIG. 12B shows the flow guiding elements for an electrodialysis device in the form of baffled concentric tubular channels.

In FIG. 12C shows other flow guiding elements for an electrodialysis device in the form of baffled concentric tubular channels.

In FIG. 12D shows flow guiding elements for an electrodialysis device in the form of parallel channels with baffles and inclined guides.

In FIG. 12E shows other flow guiding elements for an electrodialysis device in the form of parallel channels with baffles and slanted guides.

In FIG. 13A shows the manifold configuration in the basic design shown in FIG. 10A.

In FIG. 13B depicts a modified manifold that includes features that increase current efficiency and improve flow distribution.

In FIG. 14 is a diagram illustrating an example of current efficiency versus cell pair location in a single pass electrodialysis device with four galvanically isolated subassemblies.

In FIG. 15A are side, front, top and isometric views of a manifold insert for an electrodialysis device including fluid channels formed by linear profile baffles and elliptical ramps.

In FIG. 15B is a HDD model of an electrodialysis device including the manifold shown in FIG. 15A.

In FIG. 15C shows a comparison between the manifold of the basic design shown in FIG. 10 and the manifold shown in FIG. 15A.

In FIG. 15D are views of the one-piece modification of the manifold insert shown in FIG. 15A for use in electrodialysis devices with eight subassemblies.

In FIG. 15E are views of the two-piece modification of the manifold insert shown in FIG. 15A for use in electrodialysis devices with eight subassemblies.

In FIG. 15F shows a comparison between an eight-sub-unit electrodialysis apparatus manifold having a basic structure and an eight-sub-unit electrodialysis apparatus manifold including four manifold inserts shown in FIG. 15D.

In FIG. 16A shows CHD simulations of the velocity component Z through the central ZY planes and through the top, middle, and bottom ZX planes for the base and optimized designs at a flow rate of 4 m ³ /hr.

In FIG. 16B shows CHD simulations of the velocity component Z through the central ZY planes and through the top, middle, and bottom ZX planes for the base and optimized designs at a flow rate of 10 m ³ /hr.

In FIG. 16C shows CHD simulations of the Z velocity component through the ZY center planes for the basic and optimized designs shown in FIG. 15F.

In FIG. 16D depicts process efficiency versus current (fluid flow rate) for the basic and optimized designs shown in FIG. 15F.

In FIG. 17A is a plot of CHD simulation results of cell pair flow rates at various heights (y-axis positions) for the basic and optimized electrodialysis device designs at a flow rate of 4 m ³ /hr.

In FIG. 17B is a plot of CHD simulation results of cell pair flow rates at various heights (y-axis positions) for the basic and optimized electrodialysis device designs at a flow rate of 10 m ³ /hr.

In FIG. 18A is a heat map of the distribution of pressure drop across cells in a basic design of an electrodialysis system.

In FIG. 18B is a heat map of pressure drop distribution across cells in an optimized electrodialysis system design.

In FIG. 19A depicts measurement positions for pressure drop vs. flow rate in HDD simulations of basic and optimized electrodialysis system designs.

In FIG. 19B is a plot of CHD simulation results of pressure drop versus flow rate for various subassemblies in a basic electrodialysis system design.

In FIG. 19C is a plot of CHD simulation results of pressure drop versus flow rate for various subassemblies in an optimized electrodialysis system design. In FIG. 19C is a graph of the results of the CHD simulation of the pressure drop across the entire EDI device module in both the basic and optimized electrodialysis system designs.

In FIG. 20A is a cross-sectional view of the original design of the electrodialysis device manifold.

In FIG. 20B is a cross-sectional view of an alternative electrodialysis device manifold design.

In FIG. 20C is a cross-sectional view of an alternative electrodialysis device manifold design.

In FIG. 20D is a cross-sectional view of an alternative electrodialysis device manifold design.

In FIG. 21 shows simulated process efficiencies for the manifold designs shown in FIG. 20A-20C.

In FIG. 22 shows the results of a CHD simulation of the electrodialysis device shown in FIG. 20 in the cells at the top, middle and bottom of the cell stack of the electrodialysis device.

In FIG. 23A is a cross-sectional view of an electrodialysis module with four subassemblies in a two-pass configuration.

In FIG. 23B is a cross-sectional view of an electrodialysis module with four subassemblies in a two-pass configuration with curved protruding inserts mounted in manifolds.

In FIG. 24A shows simulation results of pressure distribution across the center of the entire module shown in FIG. 23A.

In FIG. 24B shows simulation results of pressure distribution across the center of the entire module shown in FIG. 23V.

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In FIG. 25 shows the simulation results of the velocity distribution through the center of the entire module shown in FIG. 23V.

In FIG. 26 shows simulation results of mass flow profiles (per cell pair) through the modules shown in FIG. 23A and FIG. 23V.

In FIG. 27 shows several examples of possible exhaust manifold inserts.

In FIG. 28 is a cross-sectional view of the first passage of a four-sub-assembly electrodialysis module in a two-pass configuration with a curved protruding insert mounted in the intake manifold and a straight conical insert in the exhaust manifold.

In FIG. 29 shows simulation results of mass flow profiles (per cell pair) through the modules shown in FIG. 28 with and without exhaust manifold insert.

In FIG. 30 is a plot of process efficiency vs. ratio of average concentrations in concentrate and diluted solution in the electrodialysis device shown in FIG. 20B and the electrodialysis device shown in FIG. 23V.

In FIG. 31A depicts fluid flow through the outlet manifold of an electrodialysis device without an outlet manifold insert.

In FIG. 31B depicts fluid flow through the outlet manifold of an electrodialysis device with an inclined outlet manifold insert.

In FIG. 32A is a table illustrating the effect of the inclined shaped outlet insert on pressure drop across the electrodialysis module in the first example.

In FIG. 32B is a table illustrating the effect of the inclined shaped manifold insert on pressure drop across the electrodialysis module in the second example.

In FIG. 33 is a cross-sectional view of an electrodialysis device having a hydraulic adapter located between the inlet manifold and the external piping.

In FIG. 34A is an isometric view of a basic embodiment of a non-optimized hydraulic adapter for an electrodialysis device.

In FIG. 34B is a partially transparent view of the hydraulic adapter shown in FIG. 34A.

In FIG. 34C is a top down view of the hydraulic adapter shown in FIG. 34A.

In FIG. 34D is a bottom-up view of the hydraulic adapter shown in FIG. 34A.

In FIG. 34E is a cross section through the first axis of the hydraulic adapter shown in FIG. 34 A.

In FIG. 34F is a cross section through the second axis of the hydraulic adapter shown in FIG. 34 A.

In FIG. 35A is a perspective view of an embodiment of an improved hydraulic adapter for an electrodialysis device.

In FIG. 35B is a partially transparent view of the hydraulic adapter shown in FIG. 35A.

In FIG. 35C is a cross section through the first axis of the hydraulic adapter shown in FIG. 36 A.

In FIG. 35D is a cross section through the second axis of the hydraulic adapter shown in FIG. 35 A.

In FIG. 36A depicts simulation results of fluid flow through an inlet manifold of an electrodialysis device including the hydraulic adapter shown in FIG. 34A.

In FIG. 36B depicts simulation results of fluid flow through an inlet manifold of an electrodialysis device including the hydraulic adapter shown in FIG. 35A.

In FIG. 37A depicts simulation results of the distribution of the Z component of the fluid distribution rate through the cells of an electrodialysis device including the hydraulic adapter shown in FIG. 34A.

In FIG. 37B depicts simulation results of the distribution of the Z component of the fluid distribution rate through the cells of an electrodialysis device including the hydraulic adapter shown in FIG. 35A.

Implementation of the invention

The aspects and embodiments disclosed herein are not limited to the details of construction and arrangement of components presented in the following description or shown in the accompanying drawings. The aspects and embodiments disclosed herein are subject to other embodiments being taken and practiced or implemented in various ways.

Electrodeionization (EDI) is a process that eliminates (or at least reduces the number of) one or more ionized or ionizable species from water using an electrically active medium and an electrical potential difference to influence ion transport. The electrically active medium generally serves to alternately trap and remove ionic and/or ionizable species and in some cases promote ion transport, which

- 8 040270 can occur continuously using ionic or electronic substitution mechanisms. EDI devices can contain an electrochemically active medium with a constant or temporary charge and operate with portions periodically, continuously and/or even in polarity reversal modes. EDI devices may operate by activating one or more electrochemical reactions specifically designed to achieve or improve performance. In addition, such electrochemical devices may contain electrically active membranes such as semipermeable or selectively permeable ion exchange or bipolar membranes. Continuous electrodeionization devices (CEDIs) are electrodeionization devices (EDIs) known to those skilled in the art that operate in a manner in which water purification can occur continuously while the ion exchange material is continuously recharged. NEDI techniques may include processes such as continuous deionization, filled cell electrodialysis, or electrodialysis. Under conditions of controlled stress and salinity, water molecules in NEDI systems can split to form hydrogen or hydronium ions or particles and hydroxide or hydroxyl ions or particles, which can regenerate the ion exchange medium in the device and thereby facilitate the release of trapped particles from it. Thus, the stream of water to be treated can be continuously purified without the need for chemical recharging of the ion exchange resin.

Electrodialysis (ED) devices operate on a similar principle to NEDI, except that ED devices generally do not contain an electroactive medium between the membranes. Due to the absence of an electrically active medium, low salinity feed waters can hamper the electrodialysis operation due to increased electrical resistance. In addition, since the operation of electrodialysis on high salinity feed waters can lead to increased consumption of electric current, electrodialysis apparatuses are most effectively used on intermediate salinity feed waters. Since there is no electroactive medium in electrodialysis based systems, water splitting is inefficient and operation in this mode is generally avoided.

In NEDI and ED devices, a plurality of adjacent cells or chambers are usually separated by selectively permeable membranes that allow the passage of either positively or negatively charged particles, but usually not both. In such devices, the dilution or depletion chambers are typically spaced apart from the concentration chambers or concentration chambers. In some embodiments, the cell pair expression may refer to a pair of adjacent concentration and dilution chambers. As water flows through the depletion chambers, ionic and other charged species are typically drawn into the concentrating chambers by an electric field, such as a DC field. Positively charged particles are attracted to the cathode, typically located at one end of a stack of multiple depletion and concentration chambers, and negatively charged particles are similarly attracted to the anode of such devices, typically located at the opposite end of the stack of chambers. The electrodes are typically enclosed in electrolyte chambers, which are usually partially isolated from fluid communication with the depletion and/or concentration chambers. Once they are in the concentration chamber, the charged particles are typically trapped in a selectively permeable membrane barrier at least partially delimiting the concentration chamber. For example, anions are typically prevented from migrating further to the cathode from the concentration chamber by means of a cation selective membrane. Once trapped in the concentration chamber, the trapped charged particles can be removed in the concentrate stream.

In NEDI and ED devices, as a rule, a DC field is applied to the cells from a voltage source and electric current supplied to the electrodes (anode or positive electrode and cathode or negative electrode). The voltage and current source itself (collectively referred to as the power source) can be powered by a variety of different means, such as an AC power source or, for example, a power source derived from solar, wind or wave energy. At the electrode/liquid interfaces, electrochemical reactions occur in the half-cell, initiating and/or facilitating the transport of ions through membranes and chambers. The specific electrochemical reactions that occur at the electrode/liquid interfaces can be controlled to some extent by salt concentration in specialized chambers containing the electrode assemblies. For example, a material fed into the anode electrolyte chambers having a high concentration of sodium chloride will tend to produce chlorine gas and hydrogen ions, while such a material fed into the cathode electrolyte chamber will tend to produce hydrogen gas and hydroxide ions. . Generally speaking, hydrogen ions formed in the anode chamber will associate with free anions such as chloride ions, maintaining charge neutrality and creating a hydrochloric acid solution, and similarly, hydroxide ions formed in the cathode chamber will associate with free cations. , such as sodium ions, maintaining charge neutrality and creating a sodium hydroxide solution. The reaction products of the electrode chambers, such as the generated chlorine gas and sodium hydroxide, can be used in the process as needed for disinfection purposes, for

- 9 040270 cleaning and cleaning of membranes, as well as in order to regulate the pH.

For various types of electrochemical deionization devices, including but not limited to electrodialysis (ED) and electrodeionization (EDI) devices, plate frame and spiral wound designs are used. Commercially available ED devices typically have a plate-and-frame design, and EDI devices are available in both plate-and-frame and helical configurations.

Prior patents have disclosed cross-flow electrodialysis (ED) devices with dilute and concentrated flows flowing in perpendicular directions. A cell pair package in a device may be assembled from one or more modular units called subunits. In FIG. 1A shows an example of a subunit. In FIG. 1B shows a package of four subassemblies before being installed in the case. As used herein, the term cell pack refers to a single sub-unit or a pack of multiple sub-blocks. In FIG. 1C shows an assembled electrodialysis device with a transparent casing. In FIG. 1D shows an assembled electrodialysis device with an opaque casing. In FIG. 1E shows a computational fluid dynamic (CFD) model of an electrodialysis device with four subassemblies.

Fluid may be supplied to the dilution chambers of the electrodialysis device through an outer tube to a transition joint as shown in FIG. 2A. The fluid is then distributed to all dilution chambers in parallel through the intake manifold as shown in FIG. 2B. Similarly, the product from all dilution chambers can be collected in the outlet manifold and delivered through the adapter to the outer pipe. The inflow and outflow of the flow from the concentrating chambers can be organized similarly to this. This flow configuration is generally referred to as single pass. The single pass configuration of the electrodialysis device is shown in FIG. 2C.

The flow through the dilution and concentration chambers can be arranged in a serpentine manner using baffles. In FIG. 2D shows a two-pass flow arrangement for the dilution stream, for example by adding baffles, where more passes can be achieved. Multiple passes in the device increase flow path length, residence time, ion transport and ion removal while still maintaining the speed in the optimum process range.

The current efficiency for a pair of cells in an electrodialysis device can be determined as follows:

where q _dl is the flow rate to the dilution chamber at the inlet, qdo is the flow rate to the dilution chamber at the outlet, d is the concentration of ions I, η, is the current efficiency, |zi| - the absolute value of the valency of the ion I (for example, zi-1 for Na ⁺ ),

F - Faraday's constant = 96 485 pendant / equivalent,

I - current, subscripts In - at the input, out - at the input.

In an ideal electrodialysis device, all of the supplied current flows through each pair of cells in series, the ion exchange membranes are ideally selective, there are no mechanical cross-leaks between the dilute stream and the concentrate, and there are no external leaks. Therefore, the current efficiency given by Equation 1 is 100%.

In a real electrodialysis device, the current efficiency would not be 100% because the membranes are not perfectly selective. A cation exchange membrane with a selectivity of 98%, for example, would provide approximately 98% of the current carried by cations transferred from the dilute stream to the concentrate and 2% of the current carried by anions transferred back to the dilute stream from the concentrate. The current efficiency would therefore decrease by about 2%. Mechanical cross-leakage from the concentrate to the dilute stream would also reduce the resulting ion transfer coefficient from the dilute stream and thus the overall current efficiency. Also, since the solutions flowing in and out of the cell pair through the intake and exhaust manifolds are conductive, some of the current will bypass the cell pair as it flows through the manifolds; it would not participate in the transport of ions, and the efficiency of the current would decrease accordingly. In FIG. 3 shows a non-ideal electrodialysis with current bypass locations indicated by dotted ovals.

A resistive circuit model was developed to simulate the bypass current path and evaluate the current efficiency under various operating conditions in an electrodialysis device. The model is simplified but assumed that the current flow in the dilute flow or concentrate cell is as shown in FIG. 4, with the arrows indicating the flow of current. An electrical circuit model for a pair of cells is shown in FIG. 5. The VDP voltage sources represent the Donnan potentials across the membranes, which must be included in the voltage drop across the cell pair.

The electrical resistance in the channel of the electrodialysis device can be calculated using Equation 2 in FIG. 6. Resistance increases as the channel width decreases, the distance between the collectors and the active area of the membrane increases, the fluid conductivity decreases, and/or the channel thickness decreases. The electrical resistance in the collector layer corresponding to a cell pair can be calculated using Equation 3 in FIG. 6. Resistance increases as the cross-sectional area of the collector decreases, the conductivity of the liquid decreases, and/or the thickness of the collector layer increases.

As the electrical resistances of the channels and/or collectors increase, the current bypassing each pair of cells decreases, with a greater proportion of the total current flowing preferentially through the active area of the membrane, thereby becoming efficient at transporting ions.

Simulation models have been run which indicate that the highest current efficiency is achieved in a single subunit in the passage. The current efficiency varies within the passage and is greatest in a pair of cells at the ends and least in a pair of cells in the middle (see Fig. 7). The average current efficiency decreases as the number of cell pairs per pass increases (see FIGS. 7 and 8). The current efficiency is a function of the applied current, dilute and concentrate flow rates, inlet dilution and concentrate concentrations, and temperature (see FIG. 8). The current efficiency decreases linearly as the ratio of the average concentrate concentration to the average dilution stream concentration increases (see FIG. 9). The average concentration is the mathematical average of the inlet and outlet concentrations, respectively.

The IOP model was developed for the four-sub-assembly single-pass cross-flow electrodialysis device disclosed above, shown in FIG. 2A and 2B. This model will essentially be considered as a basic design.

In FIG. 10A shows a central cross section of the base structure. To simplify calculations, each subblock of 100 pairs of cells was divided into 10 sections; each section represents 10 pairs of cells. Flow modeling was then performed based on this geometry. As can be seen from the graph shown in Fig. 10B, the Z component of the flow rate through each cell in the ZY plane is non-uniform, resulting in a change in the flow rate per cell pair as shown in FIG. 10C, with the flow rate being lowest in the upper cells near the fluid inlet to the manifold.

The z-velocity distribution was further characterized using ZX sectional planes passing through the top, middle, and bottom of the stack (FIGS. 11A-11C), with the total z-velocity in the top section being approximately half the speed at the bottom.

As shown in FIG. 7, the current efficiency and thus the proportion of current flowing through the membranes is greatest in the pairs of cells at the upper and lower ends of the passage. A higher current density will increase the risk of both clipping and current scaling in low flow areas. In addition, the lower flow rate through the initial dilution passage cells will prevent these cells from operating at their highest current efficiency to remove salts. Therefore, it would be preferable to ensure that all pairs of cells are stream optimized.

As described above, the fraction of the injected current that bypasses the cell pair stack through the collectors can be reduced by increasing the electrical resistance in the channels and collectors. Prior designs have been proposed that reduce current bypass (bypass) by reducing the cross-sectional area of the intake and exhaust manifolds. While these changes are effective in increasing current efficiency, they result in increased pressure drop across the manifolds and across the electrodialysis device.

In FIG. 7 and 8 show that the current efficiency decreases as the number of pairs of cells electrically coupled to a common set of collectors increases.

In an ideal hydraulic manifold design, fluid resistance values will be minimized while electrical resistance to shunt current will be maximized. This can be achieved by driving subassemblies fluidly connected in parallel but electrically isolated from each other except for communication through cell pairs.

The technical problems are thus to reduce the bypass current flow within an individual subunit, reduce the bypass current through hydraulic manifolds between subunits, provide sufficient flow to the first cell pairs in a passage, improve flow distribution across all cell pairs in a passage, and reduce to the minimum pressure required to operate such an electrodialysis device. Aspects and embodiments disclosed herein include structures and methods for solving these problems.

Aspects and embodiments disclosed herein include flow guiding elements that can be located within the hydraulic manifolds of electrodialysis devices to maximize current efficiency, normalize flow distribution, and minimize pressure drop.

As the term is used herein, a flow guiding element or fluid flow guiding device may include or consist of any of channels, grooves, ramps, tubes, tubes, baffles, vanes, or other embodiments. The profile of these elements can be a mathematical function such as linear, polynomial, trigonometric, logarithmic, conic, or freely generated.

Hydraulic element designs may consist of the above elements forming one or more channels directed to one or more subassemblies, where the flow within each channel can be further subdivided by using additional flow direction elements.

These elements can be manufactured using any of a number of methods, including, but not limited to, 3D printing, CNC machining, or injection molding.

Examples of fluid flow guiding devices may include tubular fluid channels (FIG. 12A), concentric tubular fluid channels 1215 with baffles 1205 (FIGS. 12B and 12C), and parallel channels 1225 with walls 1220 and ramps 1230 (FIGS. 12D and 12E).

As shown in FIG. 12A, pairs of baffles 1205 may define different fluid delivery areas 1210 along the length of the fluid flow guide. In other embodiments, for example as shown in FIG. 12B, multiple baffles 1205 may be included in a single fluid supply region 1210. Each of the concentric tubular channels 1215 (which may have non-circular cross sections in other embodiments) may supply fluid to a different fluid supply region 1210. In some embodiments, the lowermost fluid supply region 1210L may not include a fluid channel 1215. Each fluid supply area 1210 may supply fluid to a single submodule or subunit (SB1, SB2, SB3, SB4 in FIGS. 13A and 13B) of the cell stack. Dimensions, such as diameters, of the concentric tubular channels 1215 and gaps between adjacent concentric tubular channels 1215 can be selected to deliver predetermined amounts of fluid to different subassemblies or different regions of the cell stack. In some embodiments, the dimensions of the concentric tubular channels 1215 are chosen such that the same or substantially the same amount of fluid flow or fluid flow rate is provided to different subassemblies or different regions of the cell stack. In other embodiments, the dimensions of the concentric tubular channels 1215 are chosen such that the same or substantially the same amount of fluid flow or fluid flow rate is provided for a subset, such as sub-blocks or areas in the top and bottom regions of the cell stack, while a different, eg, lower amount of fluid flow or fluid flow rate is provided for other sub-units or regions in the cell stack, such as sub-units or regions in the central region of the cell stack.

As shown in FIG. 12D, embodiments of a fluid flow guide may include ramps 1230 located at lower ends of channels 1225 defined by walls 1220. Channels 1225 may terminate on ramps 1230. Ramps 1230 may be formed by areas of walls 1220 defining channels. 1225 that curve in the direction of the cell stack with the axis of curvature on the side of the walls 1220 closest to the cell stack (FIG. 12D) or with the axis of curvature on the side of the walls 1220 opposite of the cell stack (FIG. 12E). In some embodiments, as shown in FIG. 13B, ramps 1230 may be horizontal plates that meet walls 1220 at 90° angles. In other embodiments, for example as shown in FIG. 15A, walls 1220 may form ramps 1230 by curving along all or substantially all of their length. As also shown in FIG. 15A, an additional wall 1220 may divide the fluid delivery areas 1210 defined by the ramps 1230 into two or more sections.

Dimensions, such as length, width and/or cross-sectional area of channels 1225 can be selected to deliver given amounts of fluid to different sub-units or different regions of the cell stack. In some embodiments, channels 1225 are sized such that the same or substantially the same amount of fluid flow or fluid flow rate is provided to different sub-units or different regions of the cell stack. In other embodiments, the channels 1215 are sized such that the same or substantially the same amount of fluid flow or fluid flow rate is provided for a subset, such as subblocks or areas in the top and bottom regions of the cell stack, while the other, for example, a lower amount of fluid flow or fluid flow rate is provided to other sub-units or regions in the cell stack, such as sub-units or regions

- 12 040270 in the central region of the cell package.

In the basic design shown in Fig. 10A, the intake manifold has an initial cross-sectional area Aj and a stack height Hi (FIG. 13A). In the embodiment depicted in FIG. 13B, the flow manifold is divided into four channels 1225 with cross-sectional areas A1, A ₂ , A3 and A ₄ . The channels are formed by internal baffles or walls 1220 curving at the bottom to form ramps 1230 that can contact the joints between sub-blocks SB1, SB2, SB3 and SB4. Each channel 1225 is thus in fluid communication with only one subunit. Channels 1225 in any of FIGS. 12C, 12D, or 13B, or channels formed between or within the various concentric tubes 1215 in FIG. 12A and 12B may be fluidly isolated from each other. The sum of the cross-sectional areas of the channels 1225 in any of the FIGS. 12C, 12D or 13B or channels formed between or within the various concentric tubes 1215 in FIG. 12A and 12B may be less than the cross-sectional area of the flow manifold.

In other embodiments, the fluid guide ramps 1230 may not extend all the way to the cell stack, but end at some distance, such as between 0.5 and 2 mm, less than 2 mm (or about 2 mm), less than 1 mm (or about 1 mm), less than 0.5 mm (or about 0.5 mm) from the cell pack and form gaps having such dimensions between the ramps 1230 and the cell pack. The gaps may facilitate the installation or removal of fluid flow guides from the flow manifolds. The fluid flow guide can thus define fluid flow paths through the flow manifold between different portions of the cell stack having cross-sectional areas smaller than the cross-sectional area of the flow manifold.

In the configuration shown in FIG. 13B, hereinafter referred to as the optimal design, the flow of current from one subunit to another through the collectors is limited. Within each subunit, current may still bypass the stack through a section of collectors in fluid communication with it. To calculate the current efficiency, each subunit can therefore be modeled as if it were an electrodialysis device with only one subunit. In FIG. 14 shows the results of calculating the current efficiency for a device with four subunits; the average current efficiency is equal to the efficiency of the single subunit in FIG. 7.

In various embodiments, the electrodialysis device disclosed herein may include one or more of a fluid flow guide disposed within an intake manifold and having a surface configured to change the flow path of fluid introduced into the intake manifold, and directing the fluid into the depletion chambers or concentrating chambers, and a second fluid flow guiding device located inside the exhaust manifold and having a surface configured to change the flow path of the fluid introduced into the exhaust manifold through the depletion chambers or through the concentrating chambers.

In FIG. 15A shows one non-limiting embodiment of an optimized design consisting of fluid channels formed by baffles with a linear profile and elliptical ramps. The structure including baffles and ramps shown in FIG. 15A may be provided as an insert that may be removably installed in the manifold of the base structure. In FIG. 15B shows the optimized design embedded in the HDD model. In FIG. 15C shows a comparison of the central cross section of the electrodialysis device for the basic and optimized designs. In an optimized design, the channels are electrically isolated and hydraulically parallel.

The optimized design in Fig. 15A can be extended for use in electrodialysis modules having more than the four subunits shown in FIG. 15V and 15C. For example, a one-piece insert design of eight subassemblies is shown in FIG. 15D, and a two-piece insertion structure of eight subunits is shown in FIG. 15E. In FIG. 15D and 15E show these structures in isometric, top view, bottom view, rear view, side view, and front view. In eight subunit designs, a small channel 1505 is retained behind the manifold, below the rear side of the insert, with flow cut off at each individual ramp 1510. The ramps in the embodiments shown in FIGS. 15D and 15E are substantially planar in contrast to the curved ramps of the embodiment depicted in, for example, FIG. 12D, 12E and 15A. The term ramp as used herein includes both curved and flat or planar ramps.

In FIG. 15F shows a comparison of the central cross-section of an eight-sub-assembly electrodialysis device for the basic and optimized designs.

As described above, the flow distribution was modeled with varying operating flow rates and then optimized using the CFD software. Characterization was then performed for the Z component of the velocity, the flow rate per middle pair of cells, and the pressure drop.

- 13 040270

In FIG. 16A and 16B show the Z component of the velocity through the center ZY planes and through the top, middle and bottom ZX planes for the basic and optimized designs of FIG. 15A-15C at device flow rates of 4 m ³ /h and 10 m ³ /h, respectively. For the basic design, for all flow rates, the speed Z through the central plane ZY changes, as well as the speed Z in the upper, middle and lower planes ZX, by 2-4 times. For comparison, we note that the speed Z in the optimized design appears to be constant in all planes for all flow rates.

In FIG. 16C shows CHD simulations of the Z velocity component through the ZY center planes for the basic and optimized designs shown in FIG. 15F. The Z velocity through the center plane ZY of the optimized design is substantially more uniform than that of the base design. In FIG. 16D depicts process efficiency versus current (fluid flow rate) for the basic and optimized designs shown in FIG. 15F. The process efficiency for the optimized design is approximately 5% higher than that of the base design for each of the measured fluid flow rates.

In FIG. 17A is a graph of the results of the CHD simulation of the flow rates per cell pair at different heights (positions on the Y-axis) for the basic and optimized designs of electrodialysis devices at a flow rate of 4 m ³ /h, and FIG. 17B is a plot of CHD simulation results of cell pair flow rates at various heights (y-axis positions) for basic and optimized electrodialysis device designs at a flow rate of 10 m ³ /h. Reinforcing the above, the flow rate per middle cell is closer to uniform for an optimized design.

In FIG. 18A and 18B show the pressure distribution in the central cross section, expressed as a percentage of the maximum pressure. In the basic design (FIG. 18A), the inlet pressure of the subassemblies is uniform, while the outlet pressure varies such that pressure drops across the subassemblies increase from the top to the bottom of the subassembly (see also FIG. 19B). In the optimized design (FIG. 18B), the inlet and outlet pressures of the subassemblies vary so that the pressure drop across the subassemblies is nearly uniform (see also FIG. 19C).

In FIG. 19A shows the positions of the pressure measurement in the CFD simulation and determined the pressure differences for the individual subassemblies and the entire device. In FIG. 19B and 19C show the change in pressure drop across subassemblies 1-4 for various feed rates. The pressure drops are more uniform in the optimized design, as would be expected from a more uniform flow rate distribution per cell pair.

In another aspect, elements are provided that improve the distribution of flow among pairs of cells in the passage. In current cross-flow electrodialysis devices manufactured by Evoqua Water Technologies, the intake and exhaust manifolds are approximately triangular in cross section, as shown in FIG. 4. The adapter transfers the feed material flow in the pipe to the intake manifold. This model will essentially be considered as the initial design.

In FIG. 10B and 10C show the results of the CFD flow simulation in a batch of four sub-blocks, each with 100 cell pairs. The flow is not uniformly distributed over the cells. Comparison of the flow velocity distribution in three horizontal planes, one near the manifold inlet, one in the middle of the stack, and one at the bottom of the stack, shows that the flow through the first few cell pairs is lower, with relatively large low velocity zones (see FIGS. 11A-11C).

As shown above in FIG. 7, the current efficiency (and thus the proportion of current flowing through the membranes) is greatest in the pairs of cells at the two ends of the passage. The resulting higher current density would increase the risk of both clipping and current scaling in low flow areas. The lower flow rate through the first few dilution cells in the passage would also mean that the full potential for higher current efficiency in salt removal is not exploited.

The technical problems are thus to reduce the bypass current through the intake and exhaust manifolds, to improve the distribution of flow to the cell pairs in the passage, and in particular to provide sufficient flow to the first few cell pairs.

This document discloses designs for intake and exhaust manifolds in electrodialysis devices to improve current efficiency and improve flow distribution to cell pairs.

As described above, the efficiency of the current in a cell pair can be improved by increasing the electrical resistances in the inlet and outlet channels and manifolds. Starting from the original design shown in Fig. 20A, with the cross-sectional area A1 of the collector and the distance L1 from the edge of the active area of the membrane to the edge of the collector, there are alternative designs that can increase the efficiency of the current. A smaller manifold, such as shown in FIG. 20V, would increase the resistance in the channels at a distance L2>L1, and would also increase the resistance

- 14 040270 pressure in the collectors at A ₂ < A ₁ . The smaller manifold, as shown in Fig. 20C, would increase the resistance in the collectors at L ₃ <A1. The resistance in the channels would not change at L ₃ =L _b . The cross section, which is an isosceles trapezium with wings, is shown in Fig. 20D. The cross-sectional area of the collector in Fig. 20D is smaller than the manifold in FIG. 20V, while the average distance of the collector from the active area is approximately the same. The equation for resistance in FIG. 6 may not be applicable to this design. Even assuming that the average distance is L ₄ , due to the shunt current flow mode, it may be more complicated. The wings can direct the flow towards slower velocity zones in the active area of the membrane.

In FIG. 21 shows simulated process efficiencies for the manifold designs shown in FIG. 20A-20C. The efficiency of the process increases as the collector cross-section decreases, as expected, with two designs with the same smaller area having equal efficiency. Process efficiency is related to current efficiency and is determined by the equations in FIG. 21.

In FIG. 22 shows that the distribution of flow over cell pairs in the original design is not uniform. Cell pairs near the top of the cell stack have a lower feed rate than cell pairs at lower positions in the cell stack.

One potential solution to increase the uniformity of flow through the various cells in the original design is to embed protrusions in the header to influence the distribution of flow across the cell pairs in the passage. The protrusions may be wedges, blades, baffles, bulges, or combinations thereof. The protrusions may also have holes or slots to allow some of the flow to pass through directly, reducing eddies or eddies downstream.

A comparison between the existing design and a design including protrusions in the intake manifolds of a two-pass electrodialysis device is shown in FIG. 23A and 23B, where the structure including projections 2305 is shown in FIG. 23V. The profile of each protrusion 2305 is an arc extending from the beginning to the end of the manifold. The arc can be circular, or elliptical, or freely generated. As a term used herein, a fluid flow guide includes embodiments such as projections 2305.

IOP analysis was performed for the two electrodialysis devices depicted in FIG. 23A and 23B, each with four subassemblies located in two fluid passages. Each subblock contains 100 cell pairs, so the total number of cell pairs per pass is 200. The first device had the header cross sections shown in FIG. 23A, and the second, circular protrusions inserted into headers with the same cross-sections as shown in FIG. 23V.

In FIG. 24A shows the pressure distribution in the base case module. The pressure on the passage increases gradually from top to bottom, which would correspond to a similar velocity profile through the package. In FIG. 24B demonstrates how the pressure field can be manipulated using projections in the manifold. This example with a curved insert shows the desired parabolic pressure field with the highest pressure at the top and bottom of the passage and the lowest pressure in the middle of the passage. This corresponds to the flow (flow) field shown in FIG. 25. In FIG. 26 shows graphs of the flow rate per cell pair entering the active area per pass in the electrodialysis devices with and without ridges shown in FIG. 23V respectively. Without protrusions, the flow rate per cell is lowest in the first cell in the passage and increases throughout the passage. The protrusions change the flow distribution such that the flow rate per cell is greatest at both ends of the collector, where the current efficiency and current density in the active area of the membrane are expected to be greatest (see curve for 200 cell pairs in Fig. 7). Higher flow rates would reduce the risk of current limiting and current scaling in cells at the ends and would increase the overall removal of salts in the passage.

For collectors with a uniform cross-sectional area, the electrical circuit model disclosed above predicted that the shunt current would be highest in the middle of the pass. Reducing the cross-sectional area will decrease the shunt current and increase the efficiency of the current. The protrusions in the electrodialysis device of FIG. 23B results in intake manifold cross-sectional areas that vary throughout each pass, being smallest at the midpoint of the manifold, which will limit shunt current.

To further reduce shunt current, additional inserts can be built into the exhaust manifolds of each pass. The shape of the rates can be optimized to take up the most volume in the exhaust manifolds while maintaining the desired flow profile. Similar to inlet inserts, providing the electrodialysis device with inserts that create a small cross-sectional area at the midpoint of the exhaust manifold will greatly reduce shunt current. The geometry of the inlet manifold insert or outlet manifold insert could comprise wedges, vanes, baffles, bulges, or combinations thereof. Holes or slots could also be built in to allow some of the flow to pass through directly, reducing eddies/eddies

- 15 040270 downstream or distributing flow. Various possible designs of outlet manifold inserts are shown in FIG. 27.

CRO analysis was performed on the preliminary designs of exhaust manifold inserts using the same preliminary CFD scheme: two stages, module with two subassemblies/stages. In FIG. 28 shows the first stage of the module with inlet and outlet manifold inserts. The intake manifold insert 2805 is arc-shaped and the exhaust manifold insert 2810 is linearly tapered (tapered) with the widest portion at the top of the module and narrowest portion at the bottom of the module. As the term used herein, a fluid flow guide includes embodiments such as an intake manifold insert 2805 and an exhaust manifold insert 2810. The inlet insert was a continuous smooth curve with a mid-port apex and reduced the manifold to a 5mm bore.

The exhaust insert was a straight taper (cone) that limited the exhaust manifold to a 4mm port at the top and provided a wide open port at the bottom. The simulated flow rate was set to 12 GPM. The mass flow profiles (per cell pair) are plotted in FIG. 29 and show that if the geometry of the outlet insert is smooth and gradual, the flow profiles remain substantially unchanged when the outlet insert is provided.

Experiments were performed with two cross-flow electrodialysis devices, each with two passes, two subassemblies per pass. The first device had the collector cross-sections shown in FIG. 20B, and the second had protrusions with circular profiles shown in FIG. 23B inserted into manifolds with identical cross sections.

The flow rates of the diluted and/or concentrated flows were in the range of 40-41 l/min, corresponding to an average velocity of ~2.5 cm/s in the chambers. The dilution and concentration chambers were fed from separate tanks containing NaCl solutions. Initial concentrations were 556 mol/m ³ in the dilute feed tank and 796 mol/m ³ in the concentrate. The supplied current was 10A.

The product from the dilution chambers was returned to the dilute solution feed tank, and the reject material from the concentration chambers was returned to the concentrate feed tank. Throughout the experiment, the concentration of the dissolved salt decreased in the dilute solution reservoir and increased in the concentrate.

In FIG. 30 shows the efficiency of the process as a function of the ratio of the average concentration in the concentrate to the average concentration in the dilute solution. The ratio increased with desalting. Efficiency was approximately 10% higher in the device with inserts as a result of improved flow distribution and reduced header cross-sectional area in the middle of each pass.

Additional tests were carried out, during which the outlet insert was built into the electrochemical separation apparatus to improve flow distribution. The outlet inserts placed in the sub-assemblies had sloped or conical surfaces such that 90° turns (bends) without the inserts were converted into slopes directing the water flow with the turn instead of creating turbulence at the corners of the bends. A comparison between fluid flow with and without outlet inserts is shown in FIG. 31A and 31B. It has been found that guiding the water flow with an insert in the outlet manifold of an electrodialysis device helps to reduce the pressure drop within the module. However, the outlet insert causes fluid flow through the outlet manifold to be restricted in a manner analogous to blocking the flow in the path of a water pipe by placing an object in the path of the pipe's flow. The overall net effect was that the pressure drop was actually slightly reduced compared to the variant without the outlet insert, which was an unexpected result. The use of an inclined or conical outlet insert also increased the efficiency of the process and reduced the energy consumption of the electrodialysis machine. This data is shown in Fig. 32A and 32B.

A further aspect includes a hydraulic adapter for transferring flow from an external conduit with one cross-sectional geometry to an inlet manifold of an electrodialysis device with a different cross-sectional geometry. The hydraulic adapter includes a fluid passage comprising at least one cone section, or in some embodiments two cone sections. Each cone section has a characteristic length for the developing flow. In some embodiments, the tapered sections do not overlap.

The flow to the dilution chambers of the electrodialysis device may be supplied through an outer pipe to a hydraulic adapter and then distributed to all dilution chambers in parallel through an inlet manifold, as shown in FIG. 33. Similarly, product from all dilution chambers can be collected in the outlet manifold and delivered via a hydraulic adapter to the outer pipe. The inflow and outflow of the flow from the concentrating chambers can be organized similarly to this.

Transition of high-velocity turbulent flow from the outer pipeline to the inlet

- 16 040270 to the lecturer creates particular difficulties, since the external pipeline is generally circular in cross section, while the intake manifold may have a cross section that is essentially circular, rectangular, triangular or having some other shape. The intake manifolds, which are usually triangular, are shown in FIG. 4, 20A and 20V. In this regard, as a rule, hydraulic adapters with specialized flow guiding elements are provided.

One example of a hydraulic adapter providing a transition from a circular cross section to a predominantly triangular cross section is shown in the isometric view of FIG. 34A in the partially transparent view of FIG. 34B in a top-down view of FIG. 34C and in the bottom-up view of FIG. 34D. The inlet of this design is circular in cross section (FIG. 34C), while the outlet is approximately triangular (FIG. 34D). Inside, the flow diameter decreases along a first axis (FIGS. 34E, D1-D2), across a first characteristic length (FIGS. 34E, L1) by means of a steep, inclined cone. The flow is then allowed to expand and develop along a second axis (FIGS. 34E, D3-D4), across a second characteristic length (FIGS. 34F, L2), by means of a wide, inclined cone that overlaps with the first cone.

An improved hydraulic adapter design for the embodiments of the electrodialysis devices disclosed herein is depicted in FIG. 35A-35D. The inlet of this design is also circular in cross section, while the outlet is approximately triangular. In this design, the flow also decreases along the first axis (FIGS. 35C, D1-D2), however, the first characteristic length is longer (FIGS. 35C, L1) and the cone is smoother and more elliptical than in the previous design shown in FIGS. 34A-34F. The flow again gets the opportunity to expand and develop along the second axis (Fig. 35D, D3-D4), and similarly to the above, the second characteristic length along which the flow develops is greater (Fig. 35D, L2) than in the previous design. In this design, the cones do not overlap.

In FIG. 36A and 36B show the simulation results of the magnitude of the velocity of individual flow paths within the intake manifold, evenly sampled in the intake port, for the base and optimized designs, respectively. Due to jet effects, the speed in the intake manifold is significantly higher in the base design (left) than in the optimized design (right).

In FIG. 37A and 37B show simulation results for the Z component of fluid flow velocity through the central ZY planes and through the top, middle, and bottom ZX planes for electrodialysis devices, including the basic and optimized designs, respectively. Comparing the distribution of the Z component of the speed, we note that the change in electrodialysis devices, including the basic hydraulic adapter, is higher than in the optimized design.

The aspects and embodiments disclosed herein are not limited to an electrodialysis machine. All electrochemical separation devices can benefit from improved flow distribution. Electrochemical separation devices include, without limitation, electrodialysis, electrodialysis reversal, continuous deionization, continuous electrodeionization, electrodeionization, electrodialysis, and capacitive deionization. Other electrochemical devices that would benefit from improved flow distribution include flow batteries, fuel cells, electrochlorinating cells, and alkali and chlorine electrolyzers.

The phraseology and terminology used herein is for descriptive purposes and should not be construed as limiting. In the context of this document, the term set refers to two or more positions or components. The terms containing, including, carrying, having, containing, and embracing, as used in the textual description or claims, and the like, are non-limiting terms, i.e. means including, without limitation. Thus, the use of such terms is intended to cover the elements listed thereafter and their equivalents, as well as additional elements. Only passphrases consisting of and consisting essentially of are closed or semi-closed passphrases, respectively, with respect to the claims. The use of ordinal terms, such as first, second, third, etc., in a claim to modify a claim element does not in itself imply any precedence, precedence, or order of one claim element over another, or the temporal order in which method, but is used simply as labels to distinguish one element of a formula with a specific name from another element with the same name (but using an ordinal term), which allows you to distinguish between the elements indicated in the formula.

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Claims (28)

CLAIM 1. An electrochemical separation device comprising a first electrode; second electrode; a cell stack including alternating depletion chambers and concentrating chambers disposed between the first electrode and the second electrode; an intake manifold configured to introduce fluid into the depletion chambers or into the concentration chambers; an exhaust manifold; a fluid flow guide located inside the intake manifold and comprising a plurality of inclined guides configured to change the flow path of the fluid introduced into the intake manifold and direct the fluid to the depletion chambers or to the concentrating chambers; and a second fluid flow guide located within the exhaust manifold and comprising a plurality of inclined guides configured to change the flow path of the fluid introduced into the exhaust manifold through the depletion chambers or through the concentrating chambers. 2. The apparatus of claim 1, wherein the fluid flow path through the depletion chambers is perpendicular to the fluid flow path through the concentrating chambers. 3. The device according to claim 2, characterized in that the fluid flow guide is located inside the intake manifold and is configured to at least partially block shunt current through the intake manifold. 4. The apparatus of claim 3, wherein the fluid flow guide defines a fluid flow path through the intake manifold between different portions of the cell stack having a cross-sectional area smaller than the intake manifold's cross-sectional area. 5. The device according to claim 4, characterized in that the cell stack includes a plurality of sub-units, and the ramps are configured to direct fluid into various respective sub-units of the plurality of sub-units. 6. The device according to claim 5, characterized in that a gap of less than 1 mm is formed between the edges of each of the inclined guides and the cell pack. 7. The device according to claim 5, characterized in that the fluid flow guide device includes a plurality of channels fluidly isolated from each other. 8. Device according to claim 7, characterized in that each of the plurality of channels ends at a corresponding ramp from the plurality of ramps. 9. The device according to claim 8, characterized in that the sum of the cross-sectional areas of the plurality of channels is less than the cross-sectional area of the intake manifold. 10. The apparatus of claim 9, further comprising a second cell stack forming alternating second depletion chambers and second concentrating chambers located between the cell stack and the second electrode; a second intake manifold aligned with the exhaust manifold and configured to introduce fluid from the exhaust manifold into the second depletion chambers or the second concentrating chambers; a third fluid flow guide located within the second intake manifold and comprising a plurality of inclined guides configured to change the flow path of the fluid introduced into the second intake manifold and direct the fluid into the second depletion chambers or the second concentrating chambers; a second exhaust manifold located on the opposite side of the second cell stack relative to the second intake manifold; and a baffle fluidly separating the intake manifold from the second exhaust manifold. 11. The apparatus of claim 3, wherein the cell stack includes a plurality of subunits and the fluid flow guide includes a plurality of baffles configured to isolate fluid flow into each of the plurality of subunits from fluid flow into others from multiple sub-blocks. 12. The apparatus of claim 11, wherein the fluid flow guide further includes concentric fluid channels. 13. The device according to claim 3, characterized in that the fluid flow guiding device includes a curved protrusion extending inwardly in the direction of the cell stack from the intake manifold wall. - 18 040270 14. The device according to claim 13, characterized in that the fluid flow guiding device is configured to reduce the cross-sectional area of the intake manifold by a first amount at the end of the intake manifold and by a second amount greater than the first amount at a midpoint along the length intake manifold. 15. The device according to claim 14, characterized in that the fluid flow guiding device is configured to reduce the flow rate of fluid through the chambers in the central region of the cell stack. 16. The apparatus of claim 15, wherein the second fluid flow guide has a cross-sectional area that decreases along the path through the exhaust manifold. 17. The device according to claim 16, characterized in that the second fluid flow guiding device is adapted to reduce the pressure drop of the fluid through the device. 18. The apparatus of claim 1 further comprising a fluid inlet having a different cross section than the intake manifold and a hydraulic adapter positioned between the fluid inlet and the intake manifold. 19. The device according to claim 18, characterized in that the hydraulic adapter includes a channel having a first section with an inward cone, in which the width of the tube decreases along the first axis, and a second section with an outward cone, in which the width of the channel increases along the second axis, while the first section and the second section do not overlap. 20. The device according to claim 19, characterized in that the inwardly directed cone of the first channel section is an elliptical cone. 21. The apparatus of claim 1, further comprising a recirculation channel configured to direct the concentrate that has passed through the concentration chambers back to the concentration chambers. 22. The apparatus of claim 1, wherein the intake manifold is divided into fluid-isolated passages configured to direct predetermined amounts of fluid to different portions of the cell stack. 23. The apparatus of claim 22, wherein the fluid-isolated channels have cross-sectional areas selected to cause the fluid flow rate through the chambers in the central region of the cell stack to be less than the fluid flow rate through the chambers in the cell stack. the top and bottom areas of the cell pack. 24. The apparatus of claim 22, wherein the fluid-isolated channels have cross-sectional areas selected to cause a fluid flow rate through the chambers in the upper region of the cell stack to be substantially equal to the fluid flow rate through the chambers in the cell stack. bottom area of the cell pack. 25. A method for improving current efficiency in an electrochemical separation apparatus including a cell stack forming alternating depletion chambers and concentrating chambers located between the first electrode and the second electrode, wherein the fluid flow path through the depletion chambers is perpendicular to the fluid flow path through the concentrating chambers , and the method includes the following step: inserting a fluid flow guide into the inlet manifold of the apparatus, wherein the fluid flow guide comprises a plurality of inclined guides configured to change the flow path of the fluid introduced into the intake manifold and direct the fluid into one of the plurality of depletion chambers, or a plurality of concentrating chambers, wherein the ramps are configured to prevent fluid flow from bypassing any of the depletion or concentrating chambers and at least partially blocking shunt current through the intake manifold. 26. The method of claim 25, further comprising increasing uniformity of fluid flow through the cell stack by providing a hydraulic adapter at the inlet of the intake manifold, wherein the hydraulic adapter includes a conduit having a first section with an inwardly directed cone, in which the width of the conduit decreases along the first axis, and a second section with an outwardly directed cone, in which the width of the channel increases along the second axis, while the first section and the second section do not overlap. 27. The method of claim 26, further comprising reducing pressure drop across the apparatus by providing a conical fluid flow guide in the apparatus outlet manifold. 28. The method of claim 26, further comprising providing a second fluid flow guide in the exhaust manifold of the apparatus, wherein the second fluid flow guide has a curved surface that narrows the flow path through the exhaust manifold by a first amount on average. point along the length of the exhaust manifold and on -