Portable water quality purification filter and SPE water electrolysis hydrogen production system

Abstract

The embodiment provides a portable water quality purification filter and an SPE water electrolysis hydrogen production system, and relates to the technical field of hydrogen production, and the filter comprises a shell, a first joint, a second joint, a first filter plate, a second filter plate and a positioning mechanism. The shell is provided with a first feeding and discharging port and a second feeding and discharging port which are arranged at intervals in the axial direction of the shell. The first connector and the second connector are both installed on the shell and distributed at the two ends of the shell, and the first connector, the second connector and the shell are matched to define a flowing cavity. The first filter plate and the second filter plate are both installed in the flowing cavity, a containing cavity used for being filled with resin is formed between the first filter plate and the second filter plate, and the first feeding and discharging port and the second feeding and discharging port are both communicated with the containing cavity; the positioning mechanism is installed on the shell and used for being detachably connected with the support so as to position the shell. The filter is low in operation cost.

Description

Technical Field

[0001] This utility model relates to the field of hydrogen production technology, specifically to a portable water purification filter and an SPE water electrolysis hydrogen production system. Background Technology

[0002] The core principle of the SPE water electrolysis hydrogen production system is the electrolysis of pure water in an electrolyzer to produce hydrogen and oxygen. The reaction process in the electrolyzer is highly sensitive to water quality; substandard water quality reduces the activity of the membrane electrode assembly catalyst, leading to lower hydrogen purity and increasing the risk of safety accidents. Therefore, it is crucial to control the quality of the electrolyzed water. Typically, water is first drawn from a pure water system and then pumped to the oxygen separator. The circulating water originates in the oxygen separator, is drawn by a shielded pump, filtered by a water purification filter, and then enters the electrolyzer. The gas and water produced in the electrolyzer flow into a radiator and finally return to the oxygen separator. The circulating water needs to be continuously filtered through a water purification filter to remove impurities accumulated during the circulation process. Therefore, the water purification filter plays a vital role in the operation of the SPE water electrolysis hydrogen production system.

[0003] With the goal of "carbon neutrality and carbon peaking," the market demand for SPE water electrolysis hydrogen production systems has surged. Maintainability, a key concern in equipment use, necessitates consideration of the replaceability and ease of replacement of water purification filters. Water purification filters mainly consist of resin, filter screens, and a housing. The filter screens must prevent resin from entering the electrolyzer while ensuring sufficient contact between the circulating water and the resin. Resin can clog the filter screens due to water flow, leading to reduced circulating water flow and, in severe cases, complete cessation of circulation. Resin is a consumable and requires periodic replacement. Currently, water purification filters typically use a cartridge design with a filter plate on one side and resin in the middle. The cartridge is connected to a flange end cap, allowing for cartridge replacement and repair through the removability of the flange. However, the large size and weight of the flange result in a larger water purification filter, hindering the miniaturization requirements of water electrolysis hydrogen production equipment. Furthermore, the weight of the water purification filter makes resin replacement difficult. Utility Model Content

[0004] The purpose of this invention includes, for example, providing a portable water purification filter and an SPE water electrolysis hydrogen production system, which can extend service life, reduce the difficulty of clogging and cleaning, and reduce operating costs.

[0005] The embodiments of this utility model can be implemented as follows:

[0006] In a first aspect, this utility model provides a portable water purification filter, comprising:

[0007] The system comprises a housing, a first connector, a second connector, a first filter plate, a second filter plate, and a positioning mechanism. The housing has a first inlet / outlet and a second inlet / outlet spaced apart along its axial direction. The first connector and the second connector are both mounted on the housing and located at both ends of the housing, cooperating with the housing to define a flow cavity. The first filter plate and the second filter plate are both installed within the flow cavity, forming a cavity for filling resin between them. The first inlet / outlet and the second inlet / outlet are both connected to the cavity. The positioning mechanism is mounted on the housing and is detachably connected to a support to position the housing.

[0008] In an optional embodiment, a detachable first sealing element is provided at the first inlet / outlet;

[0009] Or / and, a detachable second sealing element is provided at the second inlet / outlet.

[0010] Based on the above scheme, before operating the portable water purification filter, the housing is roughly vertically oriented. First, the lower inlet and outlet are sealed using a sealing device. Then, water flow is used to feed resin into the receiving chamber through the upper inlet and outlet. Once the resin has filled to a certain height, a certain gap is formed between the resin and the upper filter plate. Resin filling is then stopped, and the upper inlet and outlet are closed, completing the resin filling operation. When resin replacement is needed, the existing resin is discharged, and the resin filling operation is repeated. The operation is convenient.

[0011] In an optional embodiment, the first connector includes a first cover and a first connector, the first cover being fixedly connected to the first connector, and the first cover being welded to the housing.

[0012] Or / and, the second connector includes a second cap and a second connector, the second cap being fixedly connected to the second connector, and the second cap being welded to the housing.

[0013] Based on the above scheme, the first and second joints have good sealing performance with the shell.

[0014] In an optional embodiment, the first filter plate is welded and fixed to the first cover, and the first connector is located on the side of the first filter plate away from the second filter plate.

[0015] Based on the above scheme, the first filter plate and the first cover have good sealing performance on all four sides.

[0016] In an optional embodiment, the second filter plate is welded to the second cover, and the second connector is located on the side of the second filter plate away from the first filter plate.

[0017] Based on the above scheme, the second filter plate and the second cover have good sealing performance around them.

[0018] In an optional embodiment, a first height limiting member and a second height limiting member are provided on the outer side of the housing. The first height limiting member and the second height limiting member are arranged at intervals in the axial direction of the housing. One of the first height limiting member and the second height limiting member can be selectively connected to the positioning mechanism so as to be carried by the positioning mechanism.

[0019] Based on the above scheme, by setting a first height limiting component and a second height limiting component, when the shell is connected to the bracket using the positioning mechanism, the lower limiting component is selected as the support. After the positioning mechanism is sleeved on the outside of the shell, the shell tends to descend under its own weight, so that the height limiting component is pressed against the positioning mechanism, thereby achieving the effect of suspending the shell. The shell position is stable and the use is safe.

[0020] In an optional embodiment, at least one of the first height limiting member and the second height limiting member is configured as a ring-shaped member.

[0021] Based on the above scheme, the annular part has a large surface area and a large contact area with the positioning mechanism, resulting in a firm and reliable fit.

[0022] In an optional implementation, the positioning mechanism is configured as a clamp.

[0023] Based on the above scheme, the positioning mechanism has a simple structure, is easy to manufacture, and is easy to operate.

[0024] In an optional embodiment, the clamp includes multiple fasteners and multiple fixing units, the multiple fixing units being arranged circumferentially; each fixing unit includes a connected pipe clamp and a fixing lug, the fixing lug being provided with a fixing through hole for bolts to pass through; the pipe clamps of all the fixing units are sequentially fitted end to end to define a clamping space, the housing being inserted into the clamping space; adjacent pipe clamps are connected by corresponding fasteners, the fasteners being used to adjust the size of the clamping space.

[0025] Based on the above solution, the housing can be firmly clamped by multiple fixing units and fasteners, ensuring safe and reliable operation.

[0026] Secondly, this utility model provides an SPE water electrolysis hydrogen production system, the SPE water electrolysis hydrogen production system comprising:

[0027] An electrolytic cell, a radiator, an oxygen separator, a shielded pump, and a portable water purification filter as described in any of the preceding embodiments are connected in sequence, wherein the portable water purification filter is connected to the electrolytic cell.

[0028] The beneficial effects of this utility model embodiment include, for example:

[0029] In summary, the portable water purification filter provided in this embodiment is configured such that, in its initial state, the housing is approximately vertically oriented, with the first connector above the second connector, the first filter plate above the second filter plate, and the first inlet / outlet above the second inlet / outlet. During operation, liquid enters from the second connector at the bottom, passes through the lower second filter plate, and enters the receiving cavity to contact the resin, causing the resin to rise. After passing through the upper first filter plate, it exits from the first connector. During long-term operation, the upper first filter plate may become clogged with resin, and the resin needs to be replaced during system operation. At this time, the second inlet / outlet is opened, and water is passed through the first inlet / outlet to discharge the resin from the second inlet / outlet. After the resin is discharged, the housing is inverted, with the first connector below the second connector, the first inlet / outlet below the second inlet / outlet, and the first filter plate below the second filter plate. Then, the first inlet / outlet is closed, and liquid is introduced through the second inlet / outlet to fill the receiving cavity with new resin using the water flow. Once the resin filling is complete, the second inlet / outlet is closed. Then, the filter can be used normally. The liquid enters from the first connector at the bottom, passes through the first filter plate into the receiving chamber, and drives the resin upward. After that, the liquid passes through the second filter plate and exits from the second connector. In this way, the first filter plate can be cleared while filtration is being performed. Filtration and clearing are carried out simultaneously, which is highly efficient and low-cost. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a cross-sectional schematic diagram of a portable water purification filter according to an embodiment of this application;

[0032] Figure 2 This is a top view schematic diagram of a portable water purification filter according to an embodiment of this application;

[0033] Figure 3 This is a schematic diagram of the fixing unit in an embodiment of this application;

[0034] Figure 4 This is a schematic diagram of the SPE water electrolysis hydrogen production system according to an embodiment of this application.

[0035] icon:

[0036] 001-Resin; 100-Housing; 101-First inlet / outlet; 102-Second inlet / outlet; 103-First sealing element; 104-Second sealing element; 110-First height limiting element; 120-Second height limiting element; 130-Exhaust valve; 200-First connector; 210-First cap; 220-First connector; 300-Second connector; 310-Second cap; 320-Second connector; 4 00-First filter plate; 500-Second filter plate; 600-Positioning mechanism; 610-Fastener; 620-Fixing unit; 621-Pipe clamp; 622-Fixing lug; 623-Fixing through hole; 002-Electrolytic cell; 003-Radiator; 004-Oxygen separator; 005-Shielded pump; 006-Axial flow fan; 007-Flow monitor; 008-Temperature monitor; 009-Conductivity monitor. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0040] In the description of this utility model, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed during use, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0041] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0042] It should be noted that, where there is no conflict, the features in the embodiments of this utility model can be combined with each other.

[0043] Please refer to Figure 1 This embodiment provides a portable water purification filter, including a housing 100, a first connector 200, a second connector 300, a first filter plate 400, a second filter plate 500, and a positioning mechanism 600. The housing 100 is provided with a first inlet / outlet 101 and a second inlet / outlet 102 spaced apart along its axial direction; the first connector 200 and the second connector 300 are both mounted on the housing 100 and distributed at both ends of the housing 100, and the first connector 200, the second connector 300, and the housing 100 cooperate to define a flow cavity; the first filter plate 400 and the second filter plate 500 are both installed within the flow cavity, and a receiving cavity for filling resin 001 is formed between the first filter plate 400 and the second filter plate 500; the first inlet / outlet 101 and the second inlet / outlet 102 are both connected to the receiving cavity; the positioning mechanism 600 is mounted on the housing 100 and is used for detachable connection with a support to position the housing 100.

[0044] As described above, the working principle of the portable water purification filter provided in this embodiment is as follows:

[0045] Initially, the housing 100 is roughly vertically oriented, with the first connector 200 above the second connector 300, the first filter plate 400 above the second filter plate 500, and the first inlet / outlet 101 above the second inlet / outlet 102. During operation, liquid enters from the bottom through the second connector 300, then passes through the lower second filter plate 500 and enters the receiving cavity to contact the resin 001, causing the resin 001 to rise. After passing through the upper first filter plate 400, it exits from the first connector 200. During long-term operation, the upper first filter plate 400 may become clogged with the resin 001, and the resin 001 needs to be replaced during system operation. In this case, the second inlet / outlet 102 is opened, and water is passed through the first inlet / outlet 101 to discharge the resin 001 from the second inlet / outlet 102. After resin 001 is discharged, the housing 100 is inverted, with the first connector 200 below the second connector 300, the first inlet / outlet 101 below the second inlet / outlet 102, and the first filter plate 400 below the second filter plate 500. Then, the first inlet / outlet 101 is closed, and liquid is introduced through the second inlet / outlet 102. The water flow fills the receiving cavity with new resin 001. After filling with resin 001, the second inlet / outlet 102 is closed. The filter can then be used normally. Liquid enters from the bottom through the first connector 200, passes through the first filter plate 400 into the receiving cavity, and causes the resin 001 to rise. The liquid then passes through the second filter plate 500 and exits from the second connector 300. In this way, the first filter plate 400 can be cleared simultaneously during filtration, resulting in high efficiency and low cost.

[0046] The following embodiments illustrate the detailed structure of the portable water purification filter of this application.

[0047] In this embodiment, optionally, a detachable first sealing member 103 is provided at the first inlet / outlet 101; or / and, a detachable second sealing member 104 is provided at the second inlet / outlet 102.

[0048] It should be understood that before operating the portable water purification filter, the housing 100 is generally vertically oriented. First, the lower inlet and outlet are sealed using a sealing device. Then, water flow is used to feed resin 001 into the receiving cavity from the upper inlet and outlet. Once the resin 001 has filled to a certain height, a certain gap is formed between the resin 001 and the upper filter plate. Resin 001 filling is then stopped, and the upper inlet and outlet are closed, completing the resin 001 filling operation. When resin 001 needs to be replaced, the existing resin 001 is discharged, and the resin 001 filling operation is repeated. The operation is convenient.

[0049] Please refer to Figure 1In this embodiment, optionally, the first connector 200 includes a first cover 210 and a first connector 220, the first cover 210 is fixedly connected to the first connector 220, and the first cover 210 is welded to the housing 100.

[0050] Or / and, the second connector 300 includes a second cover 310 and a second connector 320, the second cover 310 is fixedly connected to the second connector 320, and the second cover 310 is welded to the housing 100.

[0051] It is worth noting that in some embodiments, the first connector 200 and the second connector 300 can also be connected to the housing 100 by a threaded connection. For example, the housing 100 is generally cylindrical, and both ends of the housing 100 are provided with external threads. The first connector 200 and the second connector 300 are both screwed onto the external threads of the housing 100. The connection method between the first connector 200, the second connector 300 and the housing 100 is simple, reliable and easy to operate.

[0052] Please refer to Figure 1 In this embodiment, optionally, the first filter plate 400 is welded and fixed to the first cover 210, and the first connector 220 is located on the side of the first filter plate 400 away from the second filter plate 500.

[0053] It should be understood that in some embodiments, the first filter plate 400 can be detachably connected to the first cover 210 by means of snaps or threads.

[0054] In this embodiment, optionally, the second filter plate 500 is welded and fixed to the second cover 310, and the second connector 320 is located on the side of the second filter plate 500 away from the first filter plate 400.

[0055] It should be understood that in some embodiments, the second filter plate 500 can be detachably connected to the second cover 310 by means of snaps or threads.

[0056] Please refer to Figure 1 In this embodiment, optionally, a first height limiting member 110 and a second height limiting member 120 are provided on the outer side of the housing 100. The first height limiting member 110 and the second height limiting member 120 are arranged at intervals along the axial direction of the housing 100. One of the first height limiting member 110 and the second height limiting member 120 can be selectively connected to the positioning mechanism 600 so as to be supported by the positioning mechanism 600. By providing the first height limiting member 110 and the second height limiting member 120, when the housing 100 is connected to the bracket using the positioning mechanism 600, the lower limiting member is selected as the support. After the positioning mechanism 600 is sleeved on the outside of the housing 100, the housing 100 tends to descend under its own weight, so that the height limiting member is pressed against the positioning mechanism 600, realizing the effect of suspending the housing 100. The housing 100 is stable in position and safe to use.

[0057] It should be understood that both the first height limiting component 110 and the second height limiting component 120 can be fixed to the housing 100 by welding.

[0058] Optionally, at least one of the first height limiting member 110 and the second height limiting member 120 may be configured as a ring-shaped member. The ring-shaped member has a large surface area and a large contact area with the positioning mechanism 600, resulting in a firm and reliable fit.

[0059] Please refer to Figure 1 and Figure 2 In this embodiment, the positioning mechanism 600 is optionally configured as a clamp. The positioning mechanism 600 has a simple structure, is easy to manufacture, and is convenient to operate.

[0060] Please refer to Figure 3 In an optional embodiment, the clamp includes multiple fasteners 610 and multiple fixing units 620, which are arranged circumferentially. Each fixing unit 620 includes a connected pipe clamp 621 and a fixing lug 622, and the fixing lug 622 is provided with a fixing through hole 623 for bolts to pass through. The pipe clamps 621 of all fixing units 620 are sequentially fitted end to end to define a clamping space, and the housing 100 passes through the clamping space. Adjacent pipe clamps 621 are connected by corresponding fasteners 610, which are used to adjust the size of the clamping space.

[0061] For example, in this embodiment, there are three fixing units 620, and correspondingly, there are three fasteners 610. The three fixing units 620 are detachably connected by the three fasteners 610. It should be understood that the fasteners 610 can be bolts, etc.

[0062] Since each fixing unit 620 includes a fixing lug 622, the housing 100 can be more firmly fixed to the bracket through the cooperation of multiple fixing lugs 622.

[0063] To improve structural robustness, the pipe clamp 621 and the fixing lug 622 are fixed together by an integrated machining method.

[0064] Please refer to Figure 4 The portable water purification filter provided in this embodiment has a simple structure, small size, and is easy to assemble. At the same time, it can clean the filter plate during the filtration process without the need to design a separate structure and steps for cleaning the filter plate, which reduces the difficulty and cost of processing and manufacturing. It can also shorten the downtime of the equipment, improve operating efficiency, and reduce operating costs.

[0065] This embodiment also provides an SPE water electrolysis hydrogen production system. The SPE water electrolysis hydrogen production system includes an electrolyzer 002, a radiator 003, an oxygen separator 004, a shielded pump 005, and a portable water purification filter from any of the aforementioned embodiments, connected in sequence. The portable water purification filter is connected to the electrolyzer 002. Furthermore, an axial flow fan 006 is installed at the location of the radiator 003 to improve heat dissipation efficiency. A flow monitor 007, a temperature monitor 008, and a conductivity monitor 009 are installed on the connecting pipe between the portable water purification filter and the electrolyzer 002. An exhaust valve 130 is installed on the top of the portable water purification filter.

[0066] It should be understood that during equipment operation, circulating water starts from the oxygen separator 004 and, under the suction of the shielded pump 005, enters through the connector at the bottom of the portable water purification filter (first connector 200 or second connector 300), flushing the filter plates at the bottom. As the water flows upward, it comes into full contact with the resin 001. The water then flows out from the top connector, passing through the conductivity monitor 009, temperature monitor 008, and flow monitor 007 before entering the electrolysis tank 002. During its flow through the electrolysis tank 002, an electrolytic reaction occurs, producing oxygen and water which enter the radiator 003 and then the oxygen separator 004, forming a complete circulating water loop. The circulating water is continuously purified by the portable water purification filter. When the circulating water quality exceeds the required range, the conductivity monitor 009 alarms, and the resin 001 of the portable water purification filter is replaced. When the circulating water temperature is high, the temperature monitor 008 alarms, the axial flow fan 006 starts, and the radiator 003 works together to cool the circulating water, preventing the high temperature from damaging the resin 001 inside the water purification filter. When the equipment stops, the resin 001 descends under gravity and detaches from the top filter plate.

[0067] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A portable water purification filter, characterized by, The portable water purification filter comprises a shell (100), a first joint (200), a second joint (300), a first filter plate (400), a second filter plate (500) and a positioning mechanism (600); the shell (100) is provided with a first inlet and outlet (101) and a second inlet and outlet (102) arranged at intervals in the axial direction thereof; the first joint (200) and the second joint (300) are both mounted on the shell (100) and distributed at both ends of the shell (100), and the first joint (200), the second joint (300) and the shell (100) cooperatively define a flow cavity; the first filter plate (400) and the second filter plate (500) are both mounted in the flow cavity, and a containing cavity for filling resin (001) is formed between the first filter plate (400) and the second filter plate (500), wherein the first inlet and outlet (101) and the second inlet and outlet (102) both communicate with the containing cavity; the positioning mechanism (600) is mounted on the shell (100), and the positioning mechanism (600) is used for detachably connecting with a support to position the shell (100).

2. The portable water purification filter according to claim 1, wherein: a detachable first blocking piece (103) is arranged at the first inlet and outlet (101); or / and, a detachable second blocking piece (104) is arranged at the second inlet and outlet (102).

3. The portable water purification filter according to claim 1, wherein: the first joint (200) comprises a first cover (210) and a first connecting head (220), the first cover (210) is fixedly connected with the first connecting head (220), and the first cover (210) is welded and fixed with the shell (100); or / and, the second joint (300) comprises a second cover (310) and a second connecting head (320), the second cover (310) is fixedly connected with the second connecting head (320), and the second cover (310) is welded and fixed with the shell (100).

4. The portable water purification filter according to claim 3, wherein: the first filter plate (400) is welded and fixed with the first cover (210), and the first connecting head (220) is located on the side of the first filter plate (400) away from the second filter plate (500).

5. The portable water purification filter according to claim 3, wherein: the second filter plate (500) is welded and fixed with the second cover (310), and the second connecting head (320) is located on the side of the second filter plate (500) away from the first filter plate (400).

6. The portable water purification filter according to claim 1, wherein: ​ ​ ​ ​ ​ ​ ​ The outer side of the shell (100) is provided with a first height limiting piece (110) and a second height limiting piece (120), the first height limiting piece (110) and the second height limiting piece (120) are arranged in the axial direction of the shell (100), one of the first height limiting piece (110) and the second height limiting piece (120) is selectively connected with the positioning mechanism (600) to be carried by the positioning mechanism (600).

7. The portable water purification filter according to claim 6, characterized in that: At least one of the first height limiting piece (110) and the second height limiting piece (120) is arranged as a ring-shaped piece.

8. The portable water purification filter according to any one of claims 1-7, characterized in that: The positioning mechanism (600) is arranged as a clamp.

9. The portable water purification filter according to claim 8, characterized in that: The clamp comprises a plurality of fasteners (610) and a plurality of fixing units (620), the plurality of fixing units (620) are arranged in a circle; each fixing unit (620) comprises a pipe clamp (621) and a fixing lug (622) connected with each other, the fixing lug (622) is provided with a fixing through hole (623) for bolt passing; the pipe clamps (621) of all the fixing units (620) are sequentially and end-to-end matched to define a clamping space, the shell (100) is arranged in the clamping space; adjacent pipe clamps (621) are connected through corresponding fasteners (610), and the fasteners (610) are used to adjust the size of the clamping space.

10. A SPE water electrolysis hydrogen generation system, characterized in that, The SPE water electrolysis hydrogen production system comprises: The electrolytic cell (002), the radiator (003), the oxygen separator (004), the shielding pump (005) and the portable water purification filter according to any one of claims 1-9 are sequentially communicated, and the portable water purification filter is communicated with the electrolytic cell (002).

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