Membrane filtration system

Abstract

A piston assembly for use in a fluid circulation system includes a piston housing separated by a piston (70) within a first chamber and a second chamber. The piston (70) is movable to fluidly separate the first chamber from the second chamber and to change the volumes of the first and second chambers. At least one chamber includes two fluid ports spaced apart from each other. The piston includes a passage (82a) that connects the two fluid ports when the piston (70) is moved to one side of the first chamber and seals the first chamber from the second chamber. Furthermore, a piston (70) for use with the piston assembly is disclosed. The piston (70) enables pressurization of each chamber while providing a bypass passage through the two fluid ports.

Description

Technical Field

[0001] The present invention relates to a fluid separation system and a method of operating a fluid separation system. More specifically, the present invention relates to the design and method of components for operating a fluid separation system to improve the performance of the fluid separation system. In an embodiment, the present invention relates to a membrane filtration type desalination system.

Background Art

[0002] Recent developments in desalination and other membrane-based separation processes for the decontamination and / or purification of fluids have led to more energy-efficient system designs, as described in International Patent Publication Nos. 2020 / 039158A1 and 2022 / 096895A2. By better understanding the operating control process and component selection, for example, in line with the cleaning cycle of the device used for the desalination membrane, it has led to the development of a fluid separation system that can operate for substantially long periods without interruption for several months.

[0003] Such separation systems are designed to separate a fluid into a permeate (e.g., desalinated) and a retentate having contaminants or components that have become highly concentrated and are to be removed. The operating limits of such separation systems are brought about by scaling or fouling processes due to the chemical interaction between the highly concentrated components / contaminants intended to be concentrated and the system components. For this reason, even if the regular intervals are several months, the maintenance of the device is still required at regular intervals.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] This disclosure aims to provide solutions for improving problems associated with long-term exposure to certain concentrations of residual components in order to extend the maintenance interval of separation systems and / or extend the lifespan of system components. [Means for solving the problem]

[0006] According to a first aspect of the present invention, a piston assembly according to claim 1 for use in a fluid circulation system is disclosed, the piston assembly comprising a piston housing defining a chamber including a first chamber end and a second chamber end, the piston assembly comprising a piston body comprising a sealing portion for fluidly separating the first chamber end from the second chamber end, the piston body being movable so as to be able to change the respective volumes of the first and second chamber ends, wherein at least the first chamber end comprises a first fluid port and a second fluid port spaced apart from the first fluid port, the piston body comprising a first piston passage opening to the first side of the sealing portion, the first piston passage providing a first connecting passage from the first fluid port to the second fluid port when the piston body is positioned at the first chamber end, and the sealing portion maintaining fluid separation to the second chamber end, the piston assembly.

[0007] The piston assembly can be used as a pressurizing or filling module in a fluid separation system, specifically as or as part of a filling module as described herein as part of a further embodiment, where the filling module includes a chamber supplied by fluid ports located at different points in the filling module. The recognition underlying the present invention is that the operation of a piston assembly in such a filling module can be limited by the location of the fluid ports when it is necessary to maintain fluid flow between two ports. By providing a first piston passage in the piston that opens to one side of the sealing portion, for example, to either the "left" or "right" side, it is possible to provide a bypass conduit through the piston body to which the piston passage passes. In this way, the system operation can enable modes and phases in which the piston can pass through the fluid ports without blocking them, as would be the case without the bypass conduit.

[0008] In some embodiments, one of the first fluid port and the second fluid port is located on the end face of the first chamber.

[0009] One or more fluid ports connected by bypass conduits may be located at the end caps or other end connections of the first chamber. For example, the bypass may provide a return conduit from the axial center to the port around the axis.

[0010] In some embodiments, the other of the first fluid port and the second fluid port is located to the side of the end face of the first chamber.

[0011] One or more fluid ports connected by bypass conduits may be located on the mantle surface or side surface of the housing (e.g., a filling chamber) along which the piston body is configured to move. For example, the bypass can provide an elbow conduit from an axially located port to another port located in the mantle of the housing.

[0012] In some embodiments, the second chamber end includes a third fluid port and a fourth fluid port spaced apart from the third fluid port, where the piston body includes a second piston passage opening to the second side of the seal, the second piston passage providing a second connecting passage from the third fluid port to the fourth fluid port when the piston body is positioned at the second chamber end, and the seal maintains fluid separation from the first chamber end.

[0013] Thus, the piston body may include, for example, two bypass conduits on opposite sides. For example, one bypass conduit may be provided on the "left" side and the other on the "right" side, with the bypass conduit for the "left" port remaining fluidly isolated from the "right" port.

[0014] In some embodiments, one of the third fluid port and the fourth fluid port is located on the end face of the second chamber.

[0015] In some embodiments, the other of the third and fourth fluid ports is located to the side of the end face of the second chamber.

[0016] According to a second aspect of the present invention, a piston body as described in claim 7 is disclosed, which in a further aspect is used in conjunction with the separation system described herein or in conjunction with a piston assembly according to the first aspect, wherein the piston includes a body having an elongated extension between two opposite ends, the body having a body portion in the middle between the two opposite ends arranged to fluidly isolate the two opposite ends, where the opposite ends each include an end face and a mantle portion defined by the perimeter of the body, and the body having a piston passage extending from the end face to the mantle portion.

[0017] In some embodiments, the piston assembly or piston body includes at least one piston passage at each of its opposite ends.

[0018] In some embodiments, the piston passage includes a plurality of mantle openings on the piston body.

[0019] It is understood that the mantle opening is an opening that extends outwardly, for example, radially outwardly, to provide a port on the mantle surface of the piston.

[0020] In some embodiments, the mantle openings are radially spaced apart on the piston body.

[0021] For example, two or more mantle openings may be equally angularly spaced around the mantle.

[0022] In some embodiments, the piston body includes a groove in which one of the ports of the piston passage extends.

[0023] In some embodiments, the groove is provided around the mantle surface of the piston body.

[0024] The groove can facilitate the flow entering and exiting the mantle opening.

[0025] In some embodiments, at least one of the ports is located at the center of the end face of the piston body.

[0026] In some embodiments, at least one of the ports is located off-center from the center of the end face of the piston body.

[0027] In some embodiments, the seal portion includes the surface of the piston body.

[0028] In some embodiments, the seal portion includes one or more seal elements.

[0029] The one or more sealing elements are understood to be provided to maintain fluid isolation between the first chamber and the second chamber. The one or more sealing elements may be provided by dynamic sealing elements such as O-rings or profiled seals.

[0030] In some embodiments, the piston body includes a sensor-mountable element for use with a position sensor.

[0031] The sensor-placeable element may be a magnetic band or other suitable comparison-providing structure to enable a suitable sensor to detect the position of the piston body along the piston housing. Configurations including the sensor-placeable element may enable better and / or less precise position detection of the piston body. The sensor-placeable element may be used in conjunction with other indicators. For example, fluid pressure in the chamber may be used to indicate the piston position near the end of the chamber. However, by providing a separate (or additional) sensor-placeable element, the piston body can be located with greater reliability even when there is no pressure change that would normally only be expected when the piston is near or at the end of the chamber.

[0032] In some embodiments, the piston assembly is included in a fluid separation system and is part of a filling module that pressurizes the fluid for the separation process.

[0033] The disclosure includes fluid separation systems such as membrane separation systems, which include a separation module and a filling module for pressurizing a fluid for a separation process, wherein the filling module includes a piston assembly according to one embodiment of either the first or second embodiment.

[0034] In some embodiments, the fluid separation system is a filtration system, particularly a membrane separation system.

[0035] The system may be a desalination system, or other liquid separation systems such as a decontamination system for removing particles from liquids such as water or liquid foods such as milk, and may have other applications.

[0036] A further aspect of the present invention discloses a filtration system including a separation module and a filling module, the separation module and the filling module being supplyable via a supply line, the supply line being configured to supply to a first separation module port of the separation module via a first separation module line, to supply to a first filling port of the filling module via a first filling line, and to supply to a second filling port of the filling module via a second filling line, the system further including a branch between the first separation module port and the supply line, the branch being configured to supply to one of the first filling line and the second filling line via the other of the first filling line and the second filling line, the system being a filtration system including a line closing mechanism operable to close the first separation module line between the branch and the first separation module port.

[0037] A filtration system means a system that uses filtration to separate components and / or contaminants from a liquid. A filtration system may be provided in the form of a membrane separation system. A filtration system, such as a membrane separation system, can be used to produce a clean fluid, such as water, by reducing the load of contaminants or components to be removed, such as salts and / or particulate matter. For simplicity, as used herein, a filtration system is considered to produce a permeate (a cleaned fluid fraction) by separating it from a supply of the liquid to be separated, thereby leaving components to be removed from the permeate in a retaining liquid at a correspondingly increased concentration. As used herein, the fluid to be separated may be referred to as “unpermeated fluid” before undergoing separation, and as “concentrated fluid” if it is part of a retaining liquid.

[0038] In one example, the impermeable fluid may be brine separated from the supply fluid to produce clean water, resulting in a certain amount of higher concentration brine retained. However, the principle disclosed herein is not necessarily limited to desalination and may also be used for the removal of particulate matter such as microplastics, the separation of foods such as whey from milk, and other filtration processes.

[0039] In other applications, a fraction with a higher concentration of retained components may be the preferred product. In this specification, the term "clean" is used for the fluid removed as permeate from the source of the fluid to be separated, and the degree of cleanliness to be achieved may depend on the type of fluid, application, regulatory requirements, and other parameters.

[0040] In the desalination examples described herein, the separation process uses reverse osmosis (RO) through a selectively permeable membrane, operated by pressurizing brine on one side of the membrane module and producing dechlorinated permeate on the other side of the membrane.

[0041] The packing module is used to assist pressurization. As understood, the performance and degree of separation achieved within a given time window depend on the relative component concentrations, pressure levels, and flow rates. International Patent Publication 2020 / 039158A1 discloses a system and method for batch desalination with high efficiency by using a pressurizing chamber or packing module that can be supplied from two sides between two phases of a batch desalination process. Here, the packing module is understood as a chamber for pressurizing a liquid to be supplied to the separation module and can be operated by cycling a pressurizing and separation phase with another phase of purging and replenishment.

[0042] In such a separation system, the supply of the fluid to be separated can be easily carried out via a common supply line, supplying the separation module where the fluid separation takes place via a first separation module line, and supplying the two sides (chambers) of the filling module via a first and second filling line. In a practical setup, the second filling line is a branch (directly and / or via the filling module) from the supply line, thereby supplying the fluid to be separated to the second filling line from an impermeable supply source or by using a retaining fluid from the separation module. As described in International Patent Publication 2020 / 039158A1, the fluid supplied via the second filling line is pressurized within the filling module and supplied to the separation module. In this way, the separation module can be supplied via a first separation module port, i.e., via the separation module connection line supplied from the supply line, and via a second membrane module port from the filling module.

[0043] The recognition behind the development of further embodiments was that, in the operation of such systems, the already separated fraction of the recirculated high-concentration fluid results in a relatively high concentration of components in the retaining fluid, which in turn leads to a higher demand for membrane maintenance. In this context, membrane maintenance is understood as an effort to regenerate membrane performance. In practice, it has been found that it is difficult to regenerate membrane performance to 100%. This means that, in practice, membrane performance deteriorates over time even with regular maintenance. The proposal made by the inventors is to further reduce exposure to high concentrations of contaminants by introducing an additional flushing process, which is designed to be carried out in parts of the system where high concentrations of contaminants, such as brine, would otherwise be expected.

[0044] The disclosure introduces a line closure mechanism, such as a shutter element, that enables the second filling line to be separated from the first separation module port of the separation module. This allows the flow path to facilitate or push the supply of (unpurified) feed fluid through the second filling line and subsequently through the filling module. In this way, the line closure mechanism counterintuitively blocks a line that would otherwise allow the separation module to flush.

[0045] Since the supply fluid is typically an impermeable fluid, such as impermeable brine, it is expected to have a lower concentration than the recirculated retaining fluid. In this way, the proposed line closure mechanism allows the second filling line to be effectively flushed with an impermeable fluid, thereby reducing and substantially avoiding exposure to the retaining fluid of the concentration of retained components otherwise found in the separation module or other areas of the separation system.

[0046] Conveniently, the line closure mechanism is operated during or as part of the system's purging phase, and, if possible, before the system's replenishment phase. In this way, a clean (low-concentration) flush can be performed, while reducing the downtime impact of additional flushing operations.

[0047] In some embodiments, the line closing mechanism is provided as a component of the first isolation module port.

[0048] In some embodiments, the line closing mechanism is located within the first isolation module line between the branch and the first isolation module port.

[0049] In some embodiments, the line closing mechanism is provided as a component of the branch.

[0050] For example, the branch may be a manifold or multi-directional connection providing fluid passages for connecting the first filling line, the second filling line and / or the first separation module line, wherein at least the passages leading to and / or constituting the first separation module line are configured to be closed when actuated by a control mechanism (e.g., a controller module or a feedback control system).

[0051] In some embodiments, the line closing mechanism is provided by an isolation valve or other suitable fluid flow control valve.

[0052] The valve may be of a type that operates normally in an open state and is closed only in specific operating modes. In this way, the first membrane module line can be normally open and closed when the line closing mechanism is activated. However, this is not necessarily a requirement for all embodiments.

[0053] In some embodiments, the filling module includes a discharge port, where the system is configured to allow fluid circulation through the second filling port, at least a portion of the filling module, to the discharge port.

[0054] As can be understood, the discharge port can be used to supply pressurized fluid from the filling module to the separation module.

[0055] In some embodiments, the system includes a refilling pump in the second filling line to assist in the circulation of fluid from the supply line to the second filling port.

[0056] In some embodiments, the refilling pump can be controlled to deliver fluid at a predetermined flow rate through the second filling port and the discharge port.

[0057] In some embodiments, the system is configured to keep the second filling line open while the first separation module line is closed.

[0058] In some embodiments, the system includes a main supply pump, which is used to provide flow through the first filling line and / or the second filling line while the first separation module line is closed.

[0059] In this way, the system can be operated in flash mode or line purge mode with respect to the second filling line and / or the filling module. The refill pump may be operated to achieve a high flow velocity in order to reduce the time of the flash mode. In a practical embodiment, the flow through the second filling line is generated by the operation of the main supply pump. In this case, the refill pump may be operated to reduce interference with the fluid circulation through the second filling line. For example, the refill pump may be inactive, for example, in pass-through mode. Alternatively, the refill pump may be operated in other ways to reduce its influence on the flow velocity through the second filling line.

[0060] In some embodiments, the system includes a movable partition for separating the filling module into a first compartment and a second compartment, and a volume of the first compartment supplied through the first filling port and a volume of the second compartment supplied through the second filling port, wherein the movable partition is movable to change the volumes of the first and second compartments, respectively, and the system is configured to have an operating mode in which the movable partition is positioned to maintain a reduced volume of the second compartment while the first separation module line is closed.

[0061] It will be understood that the position of the movable bulkhead may need to ensure fluid passages between the fluid ports connecting the first and / or second compartments. Therefore, the reduced volume of the second compartment may be a volume achievable while maintaining fluid passages between the fluid ports of the second compartment. This reduces the volume that can accommodate higher concentrations of brine. Thus, it is thought that reducing the volume of the second compartment can result in a more efficient flushing procedure.

[0062] In some embodiments, the movable partition includes a bypass passage that provides a bypass line between the second filling port and the discharge port.

[0063] In some embodiments, the movable partition is provided by a piston.

[0064] The piston may be provided by one of the embodiments of the first or second aspects described above.

[0065] In some embodiments, the system is configured to include an operating mode in which the movable bulkhead is positioned to maintain a minimum volume of the second compartment while the first separation module line is closed.

[0066] In some embodiments, the minimum volume is 5%, 3%, 2%, or 1% (v / v) or less of the total volume of the first and second compartments combined.

[0067] In some embodiments, the supply line includes a passage through the filling module, the first filling line supplying to a first filling port of the filling module, and the discharge port of the filling module supplying to a second filling line.

[0068] In some embodiments, the system includes a sensor configuration configured to measure a separation value indicating the concentration of a component to be separated in at least one of the supply line, the separation module line, the first filling line, the second filling line, the filling chamber discharge port, and the discharge outlet, wherein the system is configured to operate the line closing mechanism in accordance with the separation value.

[0069] The separation value may be a measure of the concentration of the component to be removed in the permeate and / or retaining liquid, or a suitable alternative indicator. Conversely, at the permeate outlet, the separation value may be a measure of the absence or low level of the component to be removed. Thus, the separation value may indicate a decrease or increase in the concentration of each component below or above a threshold. For example, a suitable indicator of salinity in a desalination system may be provided by a conductivity sensor. Other suitable indicators may be flow rate, pressure level, etc. One or more sensors in the sensor configuration may be placed at other suitable locations in the system. For example, one or more sensors may be placed downstream of the supply valve, or downstream of the branch, in the second filling line, or at other suitable locations.

[0070] In some embodiments, the system includes a configuration that allows the line closing mechanism to be operated to close the separation module line when the separation value meets a predetermined threshold condition indicating a decrease in separation performance.

[0071] In some embodiments, the system includes a configuration that allows the line closing mechanism to be operated to keep the separation module line open when the separation value satisfies a predetermined threshold condition indicating appropriate separation performance.

[0072] For example, the line closing mechanism can be operated to flush the filling module with a predetermined amount of impermeable supply fluid.

[0073] In some embodiments, the system is configured to operate the line closing mechanism for a predetermined period of time.

[0074] Alternatively, or in addition to the sensor configuration, the line closing mechanism can be operated to close the isolation module line for a predetermined period, or otherwise keep the isolation module line open. This predetermined period can be provided as a user input or user setting. Alternatively, or in addition thereto, the predetermined period can be determined by an algorithm, a lookup table, or otherwise.

[0075] In some embodiments, the system includes a plurality of isolation modules that can be operated in parallel, and each isolation module supplied by the isolation module line includes a further branch for each further isolation module, where the line closing mechanism is located upstream of and / or integral with the said or each further branch.

[0076] The system may include two or more isolated modules that can be operated in parallel, thereby allowing the system configuration to be set up so that all or one or more of the isolated modules are operated simultaneously at any given time.

[0077] Any one or more embodiments of the first and second embodiments described above can be used in combination with any one or more embodiments of further embodiments and combinations of such embodiments. [Brief explanation of the drawing]

[0078] Next, exemplary embodiments of the present invention will be described with reference to the figures. [Figure 1] This is a schematic diagram of a conventional desalination system. [Figure 2] This is a schematic diagram of one embodiment. [Figure 3] This is a side view of the piston components. [Figure 4]This is a longitudinal cross-sectional view of the component shown in Figure 3. [Figure 5] Figure 3 is a radial cross-sectional view of the component. [Figure 6] This is a cross-sectional view of the pressure vessel in the first configuration. [Figure 7] This is a cross-sectional view of the pressure vessel in the second configuration. [Figure 8] This is a schematic diagram of an embodiment, showing different operating modes of the embodiment. [Figure 9] This is a schematic diagram of an embodiment, showing different operating modes of the embodiment. [Figure 10] This is a schematic diagram of an embodiment, showing different operating modes of the embodiment. [Figure 11] This is a schematic diagram of an embodiment, showing different operating modes of the embodiment. [Figure 12] This is a schematic diagram of an embodiment, showing different operating modes of the embodiment. [Figure 13] This graph shows the performance of different system configurations. [Figure 14] This graph shows the performance of different system configurations. [Modes for carrying out the invention]

[0079] Figure 1 shows a desalination system 100 of the type disclosed in International Patent Publication No. 2020039158A1, which constitutes a filtration system comprising a packing module 101 and a membrane module 104 for reverse osmosis, which here constitute a separation module. The packing module 101 includes two chambers 114,115 in the form of a first chamber 114 and a second chamber 115, which are fluidically separated by a movable partition 102 such as a piston 103. The movement of the movable partition 102 causes corresponding volume changes in the two chambers 114,115. The first chamber 114 includes a first packing port 121 through which a liquid fluid to be dechlorinated, such as brine, can be supplied. The second chamber 115 includes a second packing port 126 through which a fluid to be dechlorinated can be supplied, and a discharge port 124 for discharging the fluid. In this example, the first filling port 121 can be used for both filling and discharging the first chamber 114, but other designs may be used (see, for example, Figures 8 to 12 which show different ports for filling and discharging).

[0080] The membrane module 104 includes a selectively permeable barrier 105, which is a reverse osmosis membrane in the form of a helical structure separating the concentrated side 131 and the clean side 132 of the separation module 104, where the expression “concentrated” means the liquid and retained liquid to be separated, and the expression “clean” means the permeate or liquid having a lower concentration component (here: brine) to be removed after passing through the barrier 105 via the pressure applied to the fluid in the concentrated side 131 (by the coordinated operation of the first pump 108 constituting the main supply pump, the movable partition 102, and the second pump 109 constituting the refilling pump). Although illustrated as a linear element, the barrier 105 in this design is a helical or cylindrical structure separating two volumes, e.g., an outer volume from an inner volume. The concentrated side can be the inner or outer side. A feature of system 100 is that the concentration side 131 can be supplied with a liquid or retaining fluid from several (here: two) directions via either the first membrane module port 107 or the second membrane module port 106. By alternately using one of the first and second membrane module ports 106 or 107 for the liquid supply, the liquid supply can be used to clean or "flush" the accumulated concentration from the membrane 105, which otherwise might be subject to fouling due to a unidirectional gradient of the concentrated component. As understood, the ports 106, 107 may be arranged to supply the retaining fluid side from different sides, such as the opposite side of the retaining fluid side of the membrane, or they may be arranged as counterflows, or they may be provided in another suitable arrangement, which is understood to depend at least to some extent on the type of separation structure, such as the arrangement and size of the barrier / membrane modules. The clean side 132 includes an outlet 113 for discharging the clean fluid.

[0081] The impermeable liquid to be separated is supplied to system 100 via a supply line 128 having connection lines to a first filling port 121, a first membrane module port 107, and a second filling port 122. System 100 is configured such that the impermeable liquid is supplied via a first pump 108 through the first supply line 128 and then supplied to the filling module 101 via a joint or branch 116. From the branch line (including a second pump 109), the impermeable liquid is supplied to the second chamber 115 via the second filling port 122 of the filling module 101, and from there supplied to the second membrane module port 106 via the discharge port 124. Conveniently, the second filling port 122 is supplied from the supply line 128 via the branch 116, and the branch 116 is located between the supply line 128 and the membrane module 104, specifically between the first filling port 121 and the first membrane module port 106. Between the branch 116 and the first filling port, the system 100 includes a first valve 111 that can be controlled to selectively supply either the first filling port 121 or the branch 116 to supply the first membrane module port 107 and the second filling port 122. A refill pump 109 generates and / or assists the flow from the branch 116 toward the second filling port 126. The discharge port 124 of the filling module 101 is connected to the second membrane module port 106 via a second line 129. The second line 129 includes a second valve 110 and a discharge outlet 123 from the second line 129 that is controllable by a third valve 123. The second valve 110 is operably configured to control the flow from the discharge port 124 to the second membrane module port 106 and the outlet 123, and the third valve 123 is operably configured to control the flow from the second line 129 to the outlet 123.

[0082] As can be understood, by appropriately opening and closing the first valve 111, the second valve 110, and the third valve 112, the fluid is allowed to pass through the membrane module 104 from the first membrane module port 107 to the second membrane module port 106 (and then out of the system via the outlet 123), or in the reverse direction from the second membrane module port 106 to the first membrane module port 107, in which case the retaining fluid can re-enter the second filling line via the branch 116, thereby remaining in circulation. Referring to International Patent Publication No. 2020039158A1, the system 100 can be operated to perform three stages of a batch desalination process (pressurizing for separation, purging, and replenishment) in two phases. In one (first) phase, starting when the second chamber 115 is expanded and filled with brine, the first and third valves 111,112 are closed and the second valve 110 is opened. This ensures that brine is included in the closed circuit by supplying it to the first chamber 114 via the first filling port 121, so that the movable partition 102 pressurizes the brine in the second chamber 115 and supplies it to the membrane 105. In another (second) phase, brine is supplied, assisted by the second pump 109, to fill the second chamber 115 via the branch 116 and supply it to the first membrane module port 107 to flush the membrane 105, so that the concentrated retaining fluid is discharged through the discharge port outlet 123 and then through the second membrane module port 106. In the first phase, the fluid for the separation module (here: for reverse osmosis membrane separation) can be pressurized and the permeate separated from the retaining fluid, while in the second phase, the filling chamber can be replenished while the separation module is purged (or flushed). Therefore, this configuration allows the membrane module to be supplied with fluid from one side for purging (flashing) and with pressurized fluid from the other side for the membrane separation process.

[0083] The system described in International Patent Publication No. 2020039158A1 reduces the downtime required for maintenance and flushing of the film 105 by any other means, because it provides a film flush configuration that allows the film 105 to be effectively flushed at the same time that the second chamber 115 of the filling module 101 is being replenished.

[0084] The membrane flush configuration is effective in enabling desalination systems like System 100 to operate for extended periods, which led the inventors to observe that some components of a separation system operated in this manner may, by design, retain more concentrated liquids for longer periods. Higher concentrations require higher pressurized energy, which has been found to result in effects such as increased flash (waste) volume and / or fouling.

[0085] Figure 2 shows a desalination system 10, an improved version of system 100, which includes a membrane module 40 comprising a packing module 20 and a separation module. The packing module 20 includes a first packing port 22 for filling and draining a first packing chamber 24, a second packing port 26 for filling a second packing chamber 28, and a discharge port 32 for discharging the second packing chamber 24. The membrane module 40 includes a desalination membrane 42 arranged to divide the membrane module 40 into a retaining fluid (brine) section 43 and a permeate section 44. The retaining fluid section 43 includes a first membrane module port 46 and a second membrane module port 48, the first and second membrane module ports 46, 48 allowing the retaining fluid side of the membrane 42 to be supplied from different flow directions depending on different operating modes (described later). The permeate section 44 includes an outlet 45 for discharging the purified (e.g., desalination) fluid.

[0086] The first filling chamber 24 and the second filling chamber 28 are fluidically separated by a movable partition wall 50. The first supply line 11 includes a first pump 12 which constitutes the main supply pump, a second pump 14 which constitutes the refill pump, a first branch line 16 which constitutes the first filling line and supplies to the first filling port 22, a second branch line 18 which constitutes the second filling line and supplies to the second filling port 26, the second branch line 18 which is arranged so that the second pump 14 generates and / or assists flow within the second branch line 18 toward the second filling port 26, and a third branch line 34 which constitutes the separation module line and supplies to the first membrane module port 46. The second supply line 30 connects the second filling port 26 to the second membrane module port 48.

[0087] The desalination system 10 includes a first valve 52, a second valve 54, a third valve 56, and a fourth valve 58. The first valve 52 is located in the first supply line 11 between the first branch line 16 and the second branch line 18. The second valve 54 is located in the second supply line 30 between the discharge port 32 and the second membrane module port 48, upstream of the discharge outlet 60 of the second supply line 30. The third valve 56 is located in a position to control the discharge outlet 60. The fourth valve 58 constitutes a line closing mechanism and is located in the third branch line 34, between the branch supplying the second branch line 18 and the first membrane module port 46. The system 10 may include additional valves, such as a valve in the first branch line 16 upstream of the first filling port 22, but these are not described in detail in this disclosure.

[0088] In practice, the fourth valve 58 may be part of a branch such as a manifold supplying from the first supply line 11 to the second branch line 18, or part of the first membrane module port 46, or located along a part of the third branch line 34, i.e., within the isolation module line.

[0089] As can be understood, the system 10 may operate according to instructions from a controller device 25 configured to actuate the first valve 52, the second valve 54, the third valve 56, and the fourth valve 58, and may also control the operation of the pump and other components.

[0090] System 10 may be operated in several modes. In the first mode, the first, third, and fourth valves 52, 56, and 58 are open, and the second valve 54 is closed. This allows System 10 to operate in the purge and replenishment modes of System 100 in Figure 1. Impermeable liquid is supplied through the first supply line 11 and the second branch line 18 to fill the second filling chamber 28, and at the same time, impermeable liquid is supplied through the third branch line 34 portion to the first membrane module port 46 to flush the membrane 42. Excess supply liquid is discharged through the third valve 56 and the outlet 60.

[0091] In the second mode, the first and third valves 52, 56 are closed, and the second and fourth valves 54, 58 are open. This allows system 10 to operate in the pressurization and depressurization modes of system 100 in Figure 1. The fluid circulates through the second filling chamber 28, along the second supply line 30, through the retaining fluid section 43, and through a semi-closed circuit extending along the third branch line 46 and the second branch line 18, before re-entering the second filling chamber 28 via the second filling port 26.

[0092] Pressurization is achieved or assisted by supplying additional fluid from the first supply line 11 through the first pump 12 to fill the first filling chamber 24, which in turn moves the movable partition 50 to reduce the volume of the second filling chamber 28 (moving to the right in Figure 2), causing fluid pressurization, and accordingly the purified fluid passes through the desalination membrane 42.

[0093] By providing a fourth valve 58 which constitutes a line closing mechanism such as a shutter or a suitable valve mechanism, the system 10 can be operated in a third mode, also referred to herein as line purge mode. In line purge mode, the first, second, and third valves 52, 54, and 56 are opened, and the fourth valve 58 is closed, thereby closing the third branch line which constitutes the separation module line. When the third mode is initiated, the movable bulkhead 50 is moved to a position that reduces and substantially minimizes the volume of the second filling chamber 28 (i.e., the movable bulkhead 50 is moved as far to the right as possible in Figure 2). In this way, the first filling chamber 24 has an increased (substantially maximized) volume so that impermeable fluid supplied through the first supply line 11 flows through the second filling port 26 and through the second branch line 18. When the third valve 56 is open, the fluid flows through the second supply line 30 and through the outlet 60.

[0094] The fourth valve 58 may remain closed to flush the second filling line 18 and the second supply line 30 until a predetermined endpoint is reached, for example, for a predetermined time and / or until a predetermined volume of fluid and / or the concentration value measured by the sensor device indicates sufficient flushing. Flushing can be performed solely by the flow generated by the first pump 12, while the second pump 14 remains stopped. For example, the second pump 14 may be in bypass mode, depending on the type of pump, or may be activated as needed to enable flow and / or to avoid interference with the flow generated by the first pump 12.

[0095] After the supply and branch lines have been thoroughly flushed, the system can be operated to restart the first mode. For this purpose, the first and third valves 52, 56 remain open, the second valve 54 is closed, and the fourth valve 58 is opened. This process may be repeated several times by looping through the three modes described above (purge / replenishment mode, pressurization / separation mode, and line purge mode), and may be repeated as long as practically permissible by the desired period or maintenance requirements. When performed in this sequence, the line purge mode may be performed only once, or while the movable bulkhead 50 is in a position where the volume of the second filling chamber 28 is small.

[0096] The discharge outlet 60 includes a brine concentration sensor, which constitutes a sensor that measures a separation value indicating the concentration of the separated components, such as a conductivity sensor 62 configured to measure the brine concentration of the discharged brine. This allows monitoring of separation performance. Other types of sensors may be used, and sensors may be placed in other appropriate locations. By providing a sensor configuration for monitoring separation performance, the system 10 and the transition from one mode to the next can be operated in the form of closed-loop control. The measurements obtained via the concentration sensor can be used as input values ​​to determine whether the system 10 should continue to operate in line-purge mode or proceed to the first mode (purge and replenishment mode). The mode change may be made in accordance with conductivity or brine concentration values ​​indicating a low (i.e., well-cleaned) brine concentration. As understood, different concentration indicators may be used depending on the system design, the type of fluid to be separated, and / or the type of component to be separated from the fluid. The threshold for determining the concentration may be an absolute threshold or a range, a relative threshold, or a rate of change. Alternatively, or in addition to the above, the modes may be switched in accordance with timing, flow rate, flow velocity, and / or taking into account multiple parameters, in order to adjust the operation of the system based on the separation value. In some system configurations, switching between modes may be based on predetermined time intervals.

[0097] Referring to Figures 3 to 5, a piston design of a piston 70 that can be used as a movable bulkhead in the system design described herein is shown. The piston 70 includes a substantially cylindrical piston body 72 having a first piston end 72a opposite a second piston end 72b. Each piston end 72a, 72b includes substantially circular end faces 76a, 76b and mantle portions 78a, 78b, respectively. The two piston ends 72a, 72b are separated by a groove array 80 located midway (here: in the middle) on the piston body 72 between the two piston ends 72a, 72b. The groove array 80 provides seating surfaces for additional components to be placed on the piston body 72. This allows the piston body 72 to include a sealing structure, and / or a position indicator such as a magnetic band, or a combination thereof. The groove array 80 is composed of and / or may include precision-machined sealing surfaces, and / or may consist of an array of grooves for holding sealing elements such as dynamic sealing elements, such as O-rings or other suitable sealing components (not shown). Each piston end 72a, 72b is provided with a multi-arm piston conduit 82a, 82b, each piston conduit 82a, 82b including multiple arms that provide fluid passages between different surface locations of the piston body 72. In this embodiment, the piston conduits 82a, 82b are arranged symmetrically with respect to each other, so here only a single piston conduit 82a (left side in Figure 4) will be described. The piston conduit 82a includes a first axial passage arm 84 that constitutes the piston passage and opens to the end face 72a (here: opening at the center of the end face 72a). The axial passage arm 84 extends partway into the piston body 72, from the axial passage arm 84, multiple (here: four) radially extending arms 86a, b, c, d extend at equal intervals in a cross shape (see Figure 5), opening at different locations around the mantle portion 78a, and each radially extending arm 86a, b, c, d extends to a joint that provides a mantle opening.As shown in Figure 4, the mantle opening extends into a groove 79 that extends circumferentially around the mantle, facilitating the inflow and outflow of fluid through radially extending arms 86a, b, c, and d via the mantle opening within the airtight piston housing. Furthermore, the groove allows for fewer (in this case, four) radially extending arms 86a, b, c, and d to be provided while enabling fluid communication with the corresponding ports regardless of the rotation of the piston body 72. Thus, the groove 79 eliminates the need to ensure rotational alignment of the piston body 72 within the housing.

[0098] As can be seen from Figure 4, the multi-arm piston conduit 82a provides a fluid passage within the piston body from the mantle portion 78a through radially extending arms 86a, b, c, d and the axial passage 84 to the end face 76a. The description of the second multi-arm piston conduit 82b will not be repeated in this example as it is symmetrical to the first multi-arm piston conduit 82a. Thus, the piston conduits 82a and 82b each provide bypass passages (here: multi-arm conduits) from several (here: four) locations around the mantle portion 78a to the end face 76a of the piston end 72a.

[0099] The two piston conduits 82a and 82b are fluidly isolated from each other. The pistons illustrated herein have a substantially circular cross-section (see Figure 5), however, the geometric shape of the pistons may differ to correspond to the piston housing in which the pistons are placed.

[0100] The piston body may be supplied as a single-piece element or as an assembly consisting of multiple piston body elements. Multi-piece pistons can facilitate the manufacture and / or maintenance of complex piston body shapes. Furthermore, the flow paths within the piston body can have arbitrary sizes and diameters. For example, if an axial flow path, such as the axial flow path 84, occupies a large portion of the piston body's diameter, the piston body may have a ring-shaped hollow form.

[0101] Figure 6 shows a side cross-sectional view of the piston 50a in the filling chamber 20. Figure 7 shows a side cross-sectional view of the configuration including the piston 70 described above in the filling chamber 20. The configurations in Figures 6 and 7 show the same filling chamber, and the same numbers are used to describe the same components. However, the piston in Figure 6 is a general-purpose piston 50a that functions as a movable bulkhead, whereas the piston assembly in Figure 7 uses the piston 70 from Figures 3 to 5, which includes a multi-arm piston conduit 82.

[0102] In both Figures 6 and 7, the filling chamber 20 includes a chamber wall 21 that constitutes a piston housing. In this embodiment, the filling chamber 20 includes a substantially cylindrical cavity in which pistons (piston 50a in Figure 6, piston 70 in Figure 7) are arranged to be axially movable. Each piston 50a, 70 includes a seal configuration 80 that fluidly separates the filling chambers in the first filling chamber 24, which constitutes the first chamber end, and the second filling chamber 28, which constitutes the second chamber end. As can be understood, the volumes (sizes) of the first and second filling chambers 24, 28 can be altered, for example, by positioning the piston 50a or 70 along the filling chamber 20 that is affected by supplying liquid to the first filling chamber (see the description of Figure 2 above). The filling chamber 20 includes a discharge port 32 and a second filling port 26 (shown schematically only in Figures 6 and 7) on the side of the second filling chamber 28. The second filling port 26 can be used in the manner described above to supply liquid to the second filling chamber.

[0103] The piston 50a in Figure 6 does not include an internal bypass passage for the purposes of this explanation. Therefore, if it is desired to pass the fluid from the second filling port 26 to the discharge port 32, the flow path from the second filling port 26 to the discharge port 32 must be maintained by keeping a minimum volume 28a free. The minimum volume 28a is kept free by preventing the piston 50a from moving or sweeping completely to the end of the filling chamber 20. The volume can be maintained by using a contact edge (not shown) that restricts the movement of the piston, or by using other suitable limiting mechanisms such as controlling the amount of liquid supplied to the first filling chamber 24.

[0104] Referring to Figure 7, the piston 70 includes a multi-arm bypass passage in the form of an axial passage 84 (corresponding to one of the passages 82a, 82b shown in Figures 3-5) and a radial arm 86 that provides an internal flow path connecting the second filling port 26 and the discharge port 32 when the piston 70 is moved closer toward the end of the filling chamber 20. In this way, the second filling chamber 28 has a free volume 28b that is much smaller than the volume 28a shown in Figure 6. To provide exemplary values, the free volume 28b of the multi-arm fluid passage 82 (passage 84 and arms 86a, b, c, d) and the fluid passage volume may be less than 50%, 40%, 30%, 20%, or 10% of the volume 28a that can be achieved when a piston without a bypass passage is used. As understood, the volume reduction depends on the location of the fluid ports, the dimensions of the housing, and the movement of the piston. Also, the volume reduction that can actually be achieved may depend on the type of liquid and its flow properties such as its viscosity.

[0105] The configuration in Figure 7, using the piston designs described in Figures 3 to 5, is beneficial during the line purging mode described with reference to Figure 2. This is because it provides a relatively small volume 28b of the second packed chamber 28 from which the concentrated or highly concentrated retaining fluid can be retained during the flash operation of the line purging procedure. Achieving this volume reduction can have considerable advantages, because otherwise, the fluid retained in the free volume of the packed chamber could become considerably more concentrated after several recirculation cycles than that in the impermeable feed fluid. As a result, by ensuring a smaller free volume in the packed chamber, the line purging procedure (by the third operating mode described above) can be made shorter than otherwise.

[0106] Furthermore, piston designs including bypass passages have been found to facilitate draining the system when, for example, fluid needs to be removed before maintenance or disassembly for transport. Since the bypass passages help prevent port blockage, the piston designs disclosed herein allow the piston to remain in any position along the filling module without affecting the drainage procedure. As understood, the piston may also be a hollow design having, for example, larger diameter passages or more passages. Such “more hollow” piston designs may be used, for example, in applications where volume reduction is of less concern than in the bypass and / or drainage configurations.

[0107] The piston designs shown in Figures 3 to 5 may be used to provide bypass fluid supply through the first chamber of the filling module, as shown in Figures 8, 10, and 12.

[0108] Figures 8 to 12 show another desalination system 200 comprising a different separation system design, with each of Figures 8 to 12 showing the same embodiment in a different operating phase. Therefore, the same numbering is repeated for the same components of system 200, and the detailed descriptions of each figure are not repeated. Desalination system 200 constitutes an embodiment in which different aspects of this disclosure are combined. The operating phase can be defined by the operation of the system's valve array (closing and / or opening, respectively). If defined in this way, Figures 11 and 12 will be understood as showing different points in time in a certain phase.

[0109] The desalination system 200 includes a membrane module 240 which constitutes a packing module 220 and a separation module. The packing module 220 includes a first packing chamber 224 and a second packing chamber 228, a first packing port 222 for supplying the first packing chamber 224, a first discharge port 223 for discharging the first packing chamber 224, a second packing port 226 for supplying the second packing chamber 228, and a second discharge port 232 which fluidly connects the second packing chamber 228 to the membrane module 240 via a pressurized supply line 230.

[0110] The first filling chamber 224 and the second filling chamber 228 are fluidically separated by a movable partition wall 270. The first supply line 211, which constitutes the supply line, includes a first pump 212, which constitutes the main supply pump, and a first supply line section 216, where a first filling line is provided, which is a portion of the supply line for supplying to the first filling port 222. In the desalination system 200, the supply of impermeable liquid is led through the first filling port 222 and the first discharge port 223 to the second supply line section 217. The second supply line section 217 is connected to a connecting line 234, which constitutes the separation module line, and connects the membrane module 240 and the second supply line section 217 via the first membrane module port 246. The second supply line section 217 is also led to a branch line 218, which constitutes the third supply line section, i.e., a recirculation line that constitutes the second filling line and goes toward the second filling port 226. The second pump 214, which constitutes the refilling pump, is located within the branch line 218.

[0111] The membrane module 240 includes a desalination membrane 242 in a helical configuration, and divides the membrane module 240 into a retaining fluid section 243 and a permeate section 244, each having a (generally) annular volume. In this embodiment, the permeate section 244 is a generally cylindrical volume within the retaining fluid section 243. Depending on how the membrane 242 is positioned within the membrane module 240, the retaining fluid section 243 includes chambers 243a and 243b that provide free volume at the (here: left and right) ends of the coiled membrane 242, and the chambers 243a and 243b are supplied via a first membrane module port 246 connected to one chamber 243a and via a second membrane module port 248 connected to the other chamber 243b. In this way, the retaining fluid section 243 of the membrane 242 can be supplied with fluid from different directions, either through a first membrane module port 246 (here from the "left-hand" side, for purging) or a second membrane module port 248 (here from the "right-hand" side, under pressurization, for membrane separation). The permeate section 244 includes an outlet 245 for discharging permeate, such as a purified fluid (e.g., demineralized water). Although omitted for simplicity in illustration, this configuration will be understood to include a fluid conduit (not shown) extending from the permeate section 244 through the chamber 243b, fluidically isolated from the chamber 243b, and through the housing of the membrane module 240. In this way, the fluid passage from the permeate section 244 to the outlet 245 is fluidically isolated from the chambers 243a and 243b. The chamber 243b includes a membrane module discharge port 249, which connects to a discharge outlet 260 via a discharge line 264 in this example. A conductivity sensor 262, which constitutes a sensor configuration for monitoring separation performance, is located within the discharge line 264.

[0112] The desalination system 200 includes a first valve 252, a second valve 254, a third valve 256, and a fourth valve 258. The first valve 252 is located in the second supply line section 217, between the first discharge port 223 and the branch line 218. The second valve 254 is located in the pressurized supply line 230, between the second discharge port 232 and the second membrane module port 248. The third valve 256 is located in the discharge line 264, downstream of the membrane module discharge port 249, and controls the flow through the discharge line 264 toward the discharge outlet 260. The fourth valve 258 constitutes a line closing mechanism and is located in the connecting line 234 between the first membrane module port 246 on one side and the branch line 218 and the second supply line section 217 on the other side. Here, the fourth valve 258 is shown positioned away from the first membrane module port 246, but in some embodiments, the fourth valve 258 may be integrated with the port 246. As understood, the fourth valve 258 may be operated to block the flow through the connecting line 234 between the branch line 218 and the membrane module 240.

[0113] The system 200 may be operated according to the instructions of a controller device 225 (shown only in Figure 8) configured to actuate the first valve 252, the second valve 254, the third valve 256, and the fourth valve 258, or it may be configured to control the operation of the pump and other components.

[0114] In this embodiment, the movable partition 270 is constructed according to a design corresponding to the piston 70 shown in Figures 3 to 5 and includes a multi-arm fluid conduit that provides an internal bypass passage through the piston body of the movable partition 270. Ports 222 and 223 are located at the first chamber end of the filling chamber 220, and ports 226 and 232 are located at the second chamber end of the filling chamber 220.

[0115] The configuration of the multi-arm fluid conduit of the movable partition wall 270 corresponds to the positions of ports 222, 223 and 226, 232, respectively, so that the opening of the movable partition wall 270 is aligned and positioned with each of those ports. When the movable partition wall 270 is distal to the first filling port 222 (see the "left side" position in Figure 10), the internal bypass passage provides a fluid conduit from the first filling port 222 through the movable partition wall 270 to the first discharge port 223. In this way, positioning the movable partition wall 270 distally (here: to the first filling port 222) does not block the flow path to the first discharge port 223, and as a result the residual volume 224a of the first filling chamber is significantly reduced (Figure 10). Similarly, when the movable partition 270 is located distal to the second filling port 226 (see the "right side" position in Figure 12), the internal bypass passage provides a fluid conduit from the second filling port 226 through the movable partition 270 to the second discharge port 232. Positioning the movable partition 270 distally (here: to the second filling port 226) means that the flow path to the second discharge port 232 is not blocked, and as a result, the residual volume 228a of the second filling chamber is significantly reduced (Figure 12). In applications where such a volume reduction is not required, the partition 270 may correspondingly include a larger diameter axial passage or multiple passages.

[0116] Figures 10 and 12 show how the residual volumes 224a (Figure 10) and 228a (Figure 12) of the first and second filling chambers 224 and 228 are minimized in this manner. As the dead volume is reduced, the likelihood of more effective removal of high concentrations of retaining fluid by the flush treatment increases by reducing the residual volumes 224a and 228a.

[0117] In the desalination system 200, the piston 70 is used as a movable bulkhead 270, which is combined with operation including a fourth valve 258. For this purpose, the desalination system 200 can operate in a cycle of four modes, including an additional "hybrid" mode compared to the description in Figure 2. The modes are line purge mode (Figure 8), purge and replenishment mode (Figure 9), additional hybrid mode (Figure 10), and pressurization and separation mode (Figures 11 and 12).

[0118] First, describing the line purge mode or phase shown in Figure 8, the first valve 252, the second valve 254, and the third valve 256 are open, and the fourth valve 258 is closed. The line purge mode may be the first phase of operation before the initial filling of the system. Once in operation, the line purge mode may follow the pressurization and separation modes (Figures 11 and 12 below), and thus the branch line 218 is expected to be filled with retaining fluid with a relatively high concentration of the components to be removed. The movable partition 270 is at or has reached the end of the second chamber 228, which has been reduced to a minimum volume 228a. The impermeable fluid enters the first filling chamber 224 via the first supply line section 216, via the first pump 212, via the first filling port 222, via the first discharge port 223, bypassing the open first valve 252, and is supplied via the second supply line section 217. At the branch, the flow toward the first membrane module 246 is blocked by a closed fourth valve 258, and the supply passes only through the branch line 218, "flushing" the branch line 218 with impermeable liquid. The flow velocity through the branch line 218 can be controlled by the first pump 212. The flow velocity can be controlled solely by the first pump 212. In this case, the second pump 214 can be controlled so as not to affect the flow velocity, for example, by setting the second pump 214 to bypass mode and / or by ensuring that the operation of the second pump 214 maintains the desired flow velocity through the branch line 218. The impermeable liquid is expected to have a lower concentration of components to be removed than the concentrated retaining liquid from the previous separation phase. This helps the impermeable liquid flush the retaining liquid toward the second filling port 226, where it bypasses the movable partition 270. The liquid flow is allowed to pass through a second discharge port 232, a second membrane module port 248, a chamber 243b, and a membrane module discharge port 249, and through a third valve 256 that is open toward the discharge outlet 260. Effectively, the fluid can pass directly from the second membrane module port 248 through the chamber 243b and through the membrane module discharge port 249.As can be understood, closing the fourth valve 258 allows the branch line 218 to be flushed (or purged) with an impermeable liquid. This allows the retained liquid in the branch line 218 to be removed through the discharge port 249.

[0119] Referring to Figure 9, a replenishment and purging mode similar to the first mode described in relation to Figure 2 above is described. The fourth valve 258 is opened and the second valve 254 is closed, but the first valve 252 and the third valve 256 remain open. With the liquid supply continuing through the first filling chamber 224, when the second valve 254 is closed, the movable partition 270 is pushed toward the first filling port 222 (here to the left), increasing the volume and amount of liquid held in the second filling chamber 228, thereby allowing the second filling chamber to be filled with liquid supplied through the second filling port 226. For this purpose, the second pump 214 can be operated faster than the first pump 212, although this is not true for all system configurations. As understood, slower or faster filling of the second filling chamber 228 can be achieved by appropriately controlling the pumping performance of the second pump 214 and the first pump 212 relative to each other. When the second filling chamber 228 is expanded and filled, the movable partition 270 is understood to have moved toward the distal end near the first filling port 222 (to the left), and the flow velocity through the second pump 214 stops. With the fourth valve 258 open, a portion of the fluid supply bypasses the branch line 218 and flows through the separation module connecting pipe 234 and the first membrane module port 246, entering the membrane module 240 through chamber 243a. In this way, a purging aspect of this mode is provided by flushing the membrane side of the retaining fluid section 243 with impermeable fluid before it leaves the membrane module 240 through the membrane module discharge port 249. Conductivity may be monitored using a conductivity meter 262 as an alternative indicator of saline concentration. In this way, changes in conductivity values ​​may be used to individually monitor the performance of the system and / or each phase, and / or control its operation. Other sensor solutions may also be used, as understood.

[0120] Referring to Figure 10, this shows an additional mode or phase of the system that may be implemented between the first and second modes described in Figure 2 above. In the additional mode, once the second filling chamber 228 is filled, the system is controlled to maintain the movable partition 270 on the left side of the filling chamber 220. By using the movable partition as shown in Figures 3 to 5, a small-volume flow path is provided to connect the first filling port 222 to the first discharge port 223. The third valve 256 is closed and the second valve 254 is opened, but the first valve 252 and the fourth valve 258 remain open. In the additional mode, the fluid is recirculated through the pressurized supply line 230 and enters the membrane module 240 through the second membrane module port 248, passes through the membrane 242 under pressure, thereby allowing the permeate to pass through the membrane 242 and reach the end of the permeate section 244, which flows out through the outlet 245. The fluid remaining in the retaining fluid section 243 exits the membrane module through the chamber 243a and the first membrane module port 246, passes through the connection line 234, and rejoins at the branch line 218. In addition mode, the pressure level increases linearly by providing a supply of impermeable liquid from the supply line 211 to replenish the fluid volume on the retaining fluid side corresponding to the amount of permeate removed through the membrane 242.

[0121] Following the additional mode in Figure 10, pressurization and separation modes similar to the second mode described above in relation to Figure 2 are shown in Figures 11 and 12. The first valve 252 is closed. The third valve 256 remains closed, and the second valve 254 and the fourth valve 258 remain open. In the pressurization phase, the first filling chamber 224 is filled with the supply of impermeable liquid, pushing the movable partition wall 270 toward the chamber end containing the second filling port 226. This pressurizes the liquid contained in the second filling chamber 228 and forces it to recirculate through the pressurized supply line 230, through the retaining liquid section 243, and through the separation module connection line 234 to join the branch line 218. Throughout this phase, permeation through the membrane 242 continues to increase the output of the permeate through the outlet 245.

[0122] Referring to Figure 12, this shows the end of the pressurization and separation mode when the movable partition 270 reaches the end of the filling chamber 220, which includes the second filling port 226 (here: on the right). Due to the internal bypass passage (see multi-arm conduit 82a or 82b in Figures 3 to 5), the flow path remains unchanged from the second filling port 226 to the second discharge port 232. In this way, the movable partition 270 can move further toward the end of the filling chamber 220, thereby reducing the dead volume of high-concentration fluid remaining.

[0123] The process continues by switching from the pressurization and separation mode shown in Figure 12 to the line-purge mode configuration shown in Figure 8. The desalination system 200 is considered to reduce the possibility of scaling and / or fouling and lower the average pressure level during operation because the fourth valve 258 allows an operating phase (referred to herein as line-purge mode) in which the branch line 218 can be flushed with impermeable liquid, as shown in Figure 8. Furthermore, the configuration using a piston with a bypass passage can reduce the dead volume at the distal end of the filling chamber 220, as shown in Figures 10 and 12, compared to a configuration using a conventional piston design. A combination of both embodiments yields an even more improved effect.

[0124] Referring here to Figures 13 and 14, these show the pressure P (corresponding to the energy requirement for circulation) over time T (corresponding to the system operating cycle) during the initial phase of operation. Figure 13 shows a graph 400 of a system without a flush valve, corresponding to the configuration in Figure 1, and shows the measurable pressure levels during several cycles 401, 402, 403, 404, 405, 406, etc. As can be understood, each cycle has a characteristic increase during the pressurizing phase, then decreases in the next cycle, and repeats. With increasing concentration of retained components such as brine, it is possible to observe a trend baseline 409 indicating an increase in the required pressurizing energy. After several operating cycles, the trend baseline 409 no longer increases and eventually reaches a plateau (not shown in Figure 13), although its level is expected to be higher than the trend baseline 409 during the first cycle.

[0125] Referring to Figure 14, this shows graph 410 for a system including the flush valve of the present invention, which allows the branch line to be flushed with an impermeable liquid. Graph 410 shows characteristic pressure cycles 411, 412, 413, 414, 415, 416, etc., but in contrast to graph 400 in Figure 13, the trend baseline 419 is flatter (here: nearly horizontal). The trend baseline 419 may also reach a plateau level, which is expected to be a relatively low level compared to Figure 13, indicating that an additional line purging mode, i.e., flushing the filling line supplying the filling module, would help reduce the required pressurization by using an additional flushing process to reduce the amount of concentrated retaining liquid in circulation.

[0126] Herein, the present invention has been illustrated using the example of a desalination system that employs membrane separation to produce a desalination permeate from a brine supply. The principles of the present invention are also applicable to other permeation processes and / or downstream processes such as ultrafiltration, nanofiltration, and microfiltration, and will be understood to be particularly applicable when the components to be removed are intentionally made highly concentrated or retained at higher concentrations by recirculation during batch or semi-batch operation, for example, as expected during a reverse osmosis process. The principles disclosed herein are considered applicable to solutions, suspensions, and combinations thereof, for example, processes for separating salt from a solution, as well as processes for separating suspended solids such as particles, proteins, and microplastics from water and / or liquids such as liquid foods.

[0127] While the principles of the present invention have been described using exemplary embodiments, it will be understood that the invention is not limited in this way and can be implemented by other modifications as defined in the appended claims.

Claims

1. A piston assembly for use in a fluid circulation system, The piston assembly includes a piston housing that defines a chamber including a first chamber end and a second chamber end. The piston assembly includes a piston body with a sealing portion for fluidly separating the first chamber end from the second chamber end, The piston body is movably arranged so as to be able to change the volume of the first and second chamber ends, Here, at least the first chamber end includes a first fluid port and a second fluid port spaced apart from the first fluid port, The piston body includes a first piston passage that opens to the first side of the seal portion. A piston assembly wherein the first piston passage provides a first connecting passage from the first fluid port to the second fluid port when the piston body is positioned at the first chamber end, and the sealing portion maintains fluid separation to the second chamber end.

2. The piston assembly according to claim 1, wherein one of the first fluid port and the second fluid port is located on the end face of the first chamber.

3. The piston assembly according to claim 2, wherein the other of the first fluid port and the second fluid port is located to the side of the end face of the first chamber.

4. The second chamber end includes a third fluid port and a fourth fluid port spaced apart from the third fluid port. Here, the piston body includes a second piston passage that opens to the second side of the seal portion. The second piston passage provides a second connection passage from the third fluid port to the fourth fluid port when the piston body is positioned at the end of the second chamber. The piston assembly according to any one of the preceding claims, wherein the seal portion maintains fluid separation from the first chamber end.

5. The piston assembly according to claim 4, wherein one of the third fluid port and the fourth fluid port is located on the end face of the second chamber.

6. The piston assembly according to claim 5, wherein the other of the third fluid port and the fourth fluid port is located to the side of the end face of the second chamber.

7. A piston body for use in a piston assembly of a fluid circulation system, The piston body includes a body that has an elongated extension between its two opposite ends, The body includes a body portion located midway between the two opposite ends, which are arranged to fluidly isolate the two opposite ends. Here, the opposite end includes an end face and a mantle portion, each defined by the circumference of the main body. The piston body here includes a piston passage extending from the end face to the mantle portion.

8. A piston assembly according to claims 1 to 6 or a piston body according to claim 7, comprising at least one piston passage at each of the opposite ends.

9. The piston assembly according to any one of the preceding claims, wherein the piston passage includes a plurality of mantle openings on the piston body.

10. The piston assembly according to claim 9, wherein the mantle openings are arranged radially apart on the piston body.

11. The piston assembly according to any one of the preceding claims, wherein the piston body includes a groove through which one of the ports of the piston passage extends.

12. The piston assembly according to claim 11, wherein the groove is provided around the mantle surface of the piston body.

13. The piston assembly according to any one of the preceding claims, wherein one of the ports is located in the center of the end face of the piston body.

14. The piston assembly according to any one of the preceding claims, wherein one of the ports is located off-center from the end face of the piston body.

15. The piston assembly according to any one of the preceding claims, wherein the sealing portion includes the surface of the piston body.

16. The piston assembly according to any one of the preceding claims, wherein the sealing portion includes one or more sealing elements.

17. The piston assembly according to any one of the preceding claims, wherein the piston body includes a sensor-mountable element for use with a position sensor.

18. A piston assembly according to any one of the preceding claims, wherein the piston assembly is included in a fluid separation system, and the piston assembly is part of a filling module that pressurizes a fluid for the separation process.

19. A filtration system comprising a membrane module and a filling module for pressurizing a fluid for filtration, A filtration system wherein the filling module includes the piston assembly described in any one of claims 1 to 17.

20. The piston assembly according to claim 18 or the filtration system according to claim 19, wherein the filtration system is a desalination system.

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