Ion exchanger discharge system and ion exchange system

Abstract

The utility model provides a kind of ion exchanger unloading system and ion exchange system, the ion exchanger unloading system includes ion exchanger, infusion assembly and suction assembly, ion exchanger includes reaction cavity and filter screen, reaction cavity is divided into first chamber and second chamber, first chamber and second chamber are oppositely located the two sides of filter screen;Infusion assembly includes liquid storage bin, infusion pump and infusion pipeline, one end of infusion pipeline is connected liquid storage bin, the other end of infusion pipeline is connected second chamber, infusion pump is located on infusion pipeline, and infusion pump is used to make the liquid in liquid storage bin flow to second chamber;Suction assembly includes suction pipeline, resin storage bin and suction pump, one end of suction pipeline is connected first chamber, the other end of suction pipeline is connected resin storage bin, and suction pump is located on suction pipeline, and suction pump is used to make the resin in first chamber flow to resin storage bin.The utility model can improve the efficiency of resin replacement, improve the continuity and stability of production.

Description

Technical Field

[0001] This utility model relates to the field of ion exchange technology, specifically to an ion exchanger unloading system and an ion exchange system. Background Technology

[0002] Ion exchange equipment is an important piece of equipment in processes such as separation and purification of substances. During the operation of an ion exchanger, the resin particle layer inside may become saturated with adsorption, requiring the replacement of the resin particles to restore the performance of the ion exchanger.

[0003] In the technology related to resin particle unloading within ion exchangers, the specific operation involves operators opening the inspection port on the top or side of the column after the equipment is shut down, and then removing the resin particles using methods such as manual shoveling or pneumatic suction. This unloading method requires a long unloading time, which prolongs equipment downtime; furthermore, resin particles can easily spill out from the inspection port or surrounding gaps, leading to material loss and increasing production costs for the company. Utility Model Content

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention provide an ion exchanger unloading system and an ion exchange system, which can improve the efficiency of resin replacement and enhance the continuity and stability of production.

[0005] The ion exchanger unloading system provided in this embodiment includes an ion exchanger, a liquid delivery assembly, and a suction assembly. The ion exchanger includes a reaction chamber and a filter screen. The reaction chamber is divided into a first chamber and a second chamber, which are located opposite each other on both sides of the filter screen. The liquid delivery assembly includes a storage tank, a delivery pump, and a delivery pipeline. One end of the delivery pipeline is connected to the storage tank, and the other end is connected to the second chamber. The delivery pump is located on the delivery pipeline and is used to drive the liquid in the storage tank to flow into the second chamber. The suction assembly includes a suction pipeline, a resin storage tank, and a suction pump. One end of the suction pipeline is connected to the first chamber, and the other end is connected to the resin storage tank. The suction pump is located on the suction pipeline and is used to drive the resin in the first chamber to flow into the resin storage tank.

[0006] In summary, the ion exchanger unloading system provided by this embodiment of the invention, through the coordinated operation of the liquid delivery component and the suction component, ensures a stable and reliable liquid delivery and resin extraction process, which helps to improve the efficiency of resin replacement and realizes the automation and high efficiency of the resin replacement process. Furthermore, the closed-loop pipeline design of this ion exchanger unloading system effectively avoids resin particle spillage and material loss, reduces pollution to the production environment, improves the continuity and stability of production, and brings significant economic and environmental benefits to the enterprise's production and operation.

[0007] In some embodiments, the suction pipeline includes a straight pipe section and a bent pipe section connected to each other, and the bent pipe section is provided with a suction port, the opening of which is oriented toward the filter screen.

[0008] In some embodiments, the bent tube section is located within the first chamber, the suction port is located on the central axis of the first chamber, and the distance between the suction port and the filter screen is set to 3mm to 10mm.

[0009] In some embodiments, the resin storage tank is provided with an overflow port, and a return pipeline is provided between the overflow port and the storage tank.

[0010] In some embodiments, the overflow port is located in the upper middle part of the resin storage tank, and a screen is provided at the overflow port.

[0011] In some embodiments, the infusion assembly further includes a first switching valve disposed on the infusion line and located between the infusion pump and the second chamber; the aspiration assembly further includes a second switching valve disposed on the aspiration line and located between the first chamber and the aspiration pump.

[0012] And / or, the suction pump is configured as a diaphragm pump.

[0013] In some embodiments, the first chamber is located above the second chamber in the height direction of the ion exchanger, the resin storage tank is located above the ion exchanger, and a resin delivery pipeline is provided between the resin storage tank and the first chamber of the ion exchanger.

[0014] In some embodiments, a third switching valve is provided on the resin delivery pipeline, and a level gauge is provided on the ion exchanger. The level gauge is used to monitor the height change of the resin material in the reaction chamber, and the third switching valve is used to control the opening and closing of the resin delivery pipeline according to the height change of the resin material collected by the level gauge.

[0015] Furthermore, the ion exchange system provided by this utility model includes a feed storage bin, a feed pipeline, a discharge storage bin, a discharge pipeline, and an ion exchanger unloading system provided in any of the above embodiments. The two ends of the feed pipeline are connected to the feed storage bin and the first chamber, and the two ends of the discharge pipeline are connected to the second chamber and the discharge storage bin.

[0016] In some embodiments, the discharge pipeline is provided with a discharge pump, the feed pipeline is provided with a fourth switching valve, and the discharge pipeline is provided with a fifth switching valve. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an ion exchanger unloading system provided in an embodiment of this utility model.

[0018] Figure 2 This is a schematic diagram of the structure of an ion exchange system provided in an embodiment of the present invention.

[0019] Figure label:

[0020] 10. Ion exchanger; 11. Reaction chamber; 111. First chamber; 112. Second chamber; 12. Filter screen; 13. Level gauge; 14. Flow meter;

[0021] 20. Infusion assembly; 21. Storage tank; 22. Infusion pump; 23. Infusion tubing; 24. First switching valve;

[0022] 30. Suction assembly; 31. Suction pipeline; 311. Straight pipe section; 312. Bent pipe section; 313. Suction port; 32. Resin storage tank; 321. Overflow port; 322. Screen; 323. Discharge valve; 33. Suction pump; 34. Return pipeline; 35. Second switching valve;

[0023] 41. Resin delivery pipeline; 42. Third switch valve;

[0024] 51. Feed storage bin; 52. Feed pipeline; 53. Feed pump; 54. Fourth switch valve;

[0025] 61. Discharge storage bin; 62. Discharge pipeline; 63. Discharge pump; 64. Second switch valve. Detailed Implementation

[0026] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] like Figure 1As shown, one embodiment of this utility model provides an ion exchanger unloading system, which includes an ion exchanger 10, a liquid delivery assembly 20, and a suction assembly 30. The ion exchanger 10 includes a reaction chamber 11 and a filter screen 12. The reaction chamber 11 is divided into a first chamber 111 and a second chamber 112, which are located opposite each other on both sides of the filter screen 12. The liquid delivery assembly 20 includes a liquid storage tank 21, a liquid delivery pump 22, and a liquid delivery pipeline 23. One end of the liquid delivery pipeline 23 is connected to the liquid storage tank 21, and the other end of the liquid delivery pipeline 23 is connected to the second chamber 112. The liquid delivery pump 22 is mounted on the liquid delivery pipeline 23 and is used to drive the liquid in the liquid storage tank 21 to flow into the second chamber 112. The suction assembly 30 includes a suction pipe 31, a resin storage tank 32, and a suction pump 33. One end of the suction pipe 31 is connected to the first chamber 111, and the other end of the suction pipe 31 is connected to the resin storage tank 32. The suction pump 33 is mounted on the suction pipe 31 and is used to cause the resin in the first chamber 111 to flow to the resin storage tank 32.

[0028] Specifically, during operation, the ion exchanger 10 stores resin in its first chamber 111. The ion fluid to be treated undergoes an exchange reaction with the resin in the first chamber 111. The exchanged fluid then flows to the second chamber 112 until it is discharged from the ion exchanger 10. When the resin in the first chamber 111 of the ion exchanger 10 needs to be replaced due to adsorption saturation or other reasons, the infusion line 23 first starts working, delivering pre-prepared liquid (such as water, cleaning solution, etc.) from the storage tank 21 to the second chamber 112. This liquid creates a certain pressure and flow environment in the second chamber 112, which facilitates subsequent resin extraction and replacement operations.

[0029] Next, the suction pump 33 starts, generating a strong suction force through the suction pipe 31. Under the action of the suction force, the mixture of resin and delivery liquid in the first chamber 111 is rapidly extracted and flows along the suction pipe 31 to the resin storage tank 32. As the suction process continues, the resin in the first chamber 111 is gradually emptied, thus completing the unloading operation of the resin in the ion exchanger 10.

[0030] In summary, the ion exchanger unloading system provided by this embodiment of the invention, through the coordinated operation of the liquid delivery component 20 and the suction component 30, ensures stable and reliable liquid delivery and resin extraction processes, thereby improving resin replacement efficiency and achieving automation and high efficiency in the resin replacement process. Furthermore, the closed-loop pipeline design of this ion exchanger unloading system effectively prevents resin particle spillage and material loss, reduces pollution to the production environment, and improves the continuity and stability of production, bringing significant economic and environmental benefits to the enterprise's production and operation.

[0031] In this embodiment, multiple ion exchangers may be provided, and both the infusion line and the suction line may have multiple branches, each branch being connected to a corresponding ion exchanger. Figure 1 As shown, in this embodiment, there are two ion exchangers.

[0032] In some embodiments, the suction line 31 includes a straight pipe section 311 and a bent pipe section 312 connected to each other. The bent pipe section 312 is provided with a suction port 313, the opening of which faces the filter screen 12. The straight pipe section 311 provides a more regular and stable fluid channel, reducing the resistance of the resin and liquid mixture during flow, maintaining a relatively stable flow velocity and direction, and reducing the suction force loss of the suction pump 33. The bent pipe section 312 changes the suction direction, allowing the suction port 313 to face directly towards the filter screen 12, thereby more effectively drawing the resin deposited on the filter screen 12 into the suction line 31.

[0033] Furthermore, the suction port 313 is located on the central axis of the first chamber 111, and the distance between the suction port 313 and the filter screen 12 is set to 3mm to 10mm. The ion exchanger 10 has a cylindrical structure, and the suction port 313 is located on the central axis of the first chamber 111, that is, at the center of the cylindrical ion exchanger, in the mainstream fluid flow area. This ensures that the mixed fluid (a mixture of resin and water) can flow smoothly to the suction port 313, avoiding problems such as resin accumulation or uneven suction caused by turbulent fluid flow.

[0034] Secondly, regarding the distance between the suction port 313 and the filter screen 12, when the distance is less than 3mm, the distance between the suction port 313 and the filter screen 12 is too close. This causes the suction port 313 to directly contact the resin particles or impurities on the surface of the filter screen 12, making it unable to effectively suction resin particles attached to deeper layers or other locations on the filter screen 12. Especially near the inner wall of the ion exchanger 10, resin tends to accumulate. In this case, the suction port 313 is prone to clogging, affecting the normal operation of the suction system. Simultaneously, excessive suction force may cause excessive impact on the filter screen 12, damaging its structure and reducing its filtration efficiency and service life.

[0035] When the spacing is greater than 10mm, the distance between the suction port 313 and the filter screen 12 is too far, resulting in a long flow path for the fluid from the filter screen 12 to the suction port 313. The suction force will be greatly attenuated when it is transmitted to the vicinity of the filter screen 12, which further leads to poor suction effect and makes it impossible to effectively draw the resin near the filter screen 12 into the suction pipe 31.

[0036] The spacing between the suction port 313 and the filter screen 12 is controlled to be 3mm to 10mm, which can give full play to the advantages of the cylindrical structure and improve the efficiency and effect of resin suction.

[0037] In some embodiments, the resin storage tank 32 is provided with an overflow port 321, and a return pipe 34 is provided between the overflow port 321 and the liquid storage tank 21. The resin storage tank 32 typically has a certain volume to accommodate the mixture of resin and liquid drawn in from the first chamber 111 by the suction pump 33. As the suction process continues, the amount of mixed fluid in the resin storage tank 32 continuously increases. When the mixed fluid in the resin storage tank 32 exceeds the position of the overflow port 321, the water in the mixed fluid will enter the return pipe 34 through the overflow port 321, and then flow smoothly along the pipe, eventually returning to the liquid storage tank 21, forming a liquid return mechanism.

[0038] This liquid return mechanism not only effectively prevents excessive pressure in the resin storage tank 32, avoiding the risk of damage to the resin storage tank 32 due to overpressure and ensuring the stable operation of the entire unloading system, but also realizes the recycling of water resources, reduces water waste, and lowers operating costs.

[0039] Furthermore, the overflow port 321 is located in the upper middle part of the resin storage tank 32, thereby allowing the resin storage tank 32 to store as much resin as possible while reducing water. A screen 322 is provided at the overflow port 321. The pore size of the screen 322 is smaller than the particle size of the resin particles, thereby effectively separating water and resin and improving the resin recovery rate.

[0040] In other words, during the operation of the ion exchanger 10, the mixed fluid formed by the resin and liquid is drawn into the resin storage tank 32 by the suction pump 33. Since the density of resin particles is generally greater than that of liquid, the resin particles will gradually settle at the bottom of the resin storage tank 32 under the action of gravity. As the mixed fluid is continuously injected, the liquid level in the resin storage tank 32 gradually rises. When the liquid level reaches the overflow port 321, a considerable number of resin particles have accumulated at the bottom of the resin storage tank 32, while the upper layer is mainly liquid. At this time, the excess liquid can be discharged in time through the overflow port 321, while most of the resin particles remain in the resin storage tank 32, achieving maximum resin storage in the resin storage tank 32.

[0041] In some embodiments, the infusion assembly 20 further includes a first switching valve 24, which is disposed on the infusion line 23 and located between the infusion pump 22 and the second chamber 112; the aspiration assembly 30 further includes a second switching valve 35, which is disposed on the aspiration line 31 and located between the first chamber 111 and the aspiration pump 33.

[0042] When the ion exchanger 10 needs to unload, the operator can control the opening and closing states of the first switching valve 24 and the second switching valve 35 according to actual needs to achieve precise liquid delivery and effective suction of the mixed fluid. For example, when the ion exchanger 10 needs to unload, the first switching valve 24 is opened first to deliver the required liquid to the second chamber 112; after waiting for a period of time, the second switching valve 35 is opened, and the suction pump 33 is started to suction the mixed fluid in the first chamber 111 to the resin storage tank 32.

[0043] Optionally, the suction pump 33 can be configured as a diaphragm pump. It should be noted that the diaphragm pump uses a diaphragm to separate the pump's moving parts from the pumped liquid, so that resin particles will not directly contact the pump's moving parts, which can effectively avoid pump wear and damage and extend the pump's service life.

[0044] In some embodiments, the first chamber 111 is located above the second chamber 112 in the height direction of the ion exchanger 10, thereby enabling ion exchange by gravity. A resin storage tank 32 is positioned above the ion exchanger 10, and a resin delivery pipeline 41 is provided between the resin storage tank 32 and the first chamber 111 of the ion exchanger 10. This allows the resin to flow back from the resin storage tank 32 to the first chamber 111 by its own gravity, eliminating the need for additional power equipment and helping to reduce system operating and maintenance costs.

[0045] Furthermore, a third switching valve 42 is provided on the resin delivery pipeline 41, and a level gauge 13 is provided on the ion exchanger 10. The level gauge 13 is used to monitor the height change of the resin material in the reaction chamber 11, and the third switching valve 42 is used to control the opening and closing of the resin delivery pipeline 41 according to the height change of the resin material collected by the level gauge 13.

[0046] Furthermore, the unloading system also includes a discharge valve 323, which is located at the connection between the resin pipeline 41 and the resin storage tank 32.

[0047] Specifically, when the material level reaches the set upper limit threshold, the third switch valve 42 can be closed to stop the resin delivery and avoid excessive resin accumulation; when the material level gauge 13 detects that the resin material level in the reaction chamber 11 is lower than the set lower limit threshold, the third switch valve 42 can be opened to allow the resin to be delivered from the resin storage silo 32 to the first chamber 111 to replenish the resin material.

[0048] Furthermore, the ion exchanger unloading system may include a controller, which is electrically connected to the third switching valve 42 and the level gauge 13. That is, the level gauge 13 monitors the resin level in the reaction chamber 11 in real time and transmits the data to the control system; the control system determines whether the third switching valve 42 needs to be opened or closed based on a preset level threshold.

[0049] It should be noted that in some embodiments, the third switching valve 42 can be opened or closed by a controller. In other embodiments, the third switching valve 42 can also be opened or closed manually.

[0050] In this embodiment, the ion exchanger unloading system also includes multiple flow meters 14, which can be respectively installed on the infusion pipeline 23, and the flow meters are configured in a one-to-one correspondence with the infusion pipeline 23.

[0051] In addition, such as Figure 2 As shown, one embodiment of this utility model also provides an ion exchange system, which includes a feed storage tank 51, a feed pipeline 52, a discharge storage tank 61, a discharge pipeline 62, and an ion exchanger unloading system provided in any of the above embodiments. The two ends of the feed pipeline 52 are connected to the feed storage tank 51 and the first chamber 111, respectively, and the two ends of the discharge pipeline 62 are connected to the second chamber 112 and the discharge storage tank 61, respectively. The feed storage tank 51 is used to store the fluid to be processed, and the discharge storage tank 61 is used to store the fluid processed by the ion exchanger 10.

[0052] Furthermore, a feed pump 53 and a fourth switching valve 54 are installed on the feed pipeline 52. A discharge pump 63 and a fifth switching valve 64 are installed on the discharge pipeline 62. During the operation of the ion exchanger 10, when feeding needs to begin, the operator can control the opening degree of the fourth switching valve 54 to adjust the fluid feed rate, so as to transport the material into the first chamber 111 of the ion exchanger 10; and open the fifth switching valve 64 so that the treated fluid is transported to the discharge storage silo 61 through the discharge pipeline 62 under the action of the discharge pump 63.

[0053] Similarly, during the unloading process of ion exchanger 10, the fourth switch valve 54 and the fifth switch valve 64 can be closed simultaneously to start the ion exchanger unloading system and realize the unloading process of resin in ion exchanger 10. In this embodiment, flow meters 14 can also be installed on the feed pipe 52 and the discharge pipe 62.

[0054] In addition, the first switching valve 24, the second switching valve 35, the third switching valve 42, the fourth switching valve 54, the fifth switching valve 64, and the discharge valve 323 can be configured as ball valves, butterfly valves, etc., controlled manually, electrically, or pneumatically.

[0055] It should be noted that the ion exchanger unloading system provided in this application embodiment is applicable to the ion exchange system. Therefore, the implementation principle and technical effects of the ion exchange system can be referred to the corresponding content in the above-mentioned ion exchanger unloading system embodiment, and will not be repeated here.

[0056] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. 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. Therefore, they should not be construed as limitations on this utility model.

[0057] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0058] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0059] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0060] In this utility model, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An ion exchanger unloading system, characterized in that, include: An ion exchanger, comprising a reaction chamber and a filter screen, wherein the reaction chamber is divided into a first chamber and a second chamber, the first chamber and the second chamber being located opposite each other on both sides of the filter screen; An infusion assembly includes a reservoir, an infusion pump, and an infusion line. One end of the infusion line is connected to the reservoir, and the other end is connected to a second chamber. The infusion pump is located on the infusion line and is used to drive the liquid in the reservoir to flow into the second chamber. A suction assembly includes a suction pipeline, a resin reservoir, and a suction pump. One end of the suction pipeline is connected to the first chamber, and the other end of the suction pipeline is connected to the resin reservoir. The suction pump is located on the suction pipeline and is used to drive the resin in the first chamber to flow to the resin reservoir.

2. The ion exchanger unloading system according to claim 1, characterized in that, The suction pipeline includes a straight pipe section and a bent pipe section connected together. The bent pipe section is provided with a suction port, and the opening of the suction port is oriented towards the filter screen.

3. The ion exchanger unloading system according to claim 2, characterized in that, The bent tube section is located in the first chamber, the suction port is located on the central axis of the first chamber, and the distance between the suction port and the filter screen is set to 3mm to 10mm.

4. The ion exchanger unloading system according to claim 1, characterized in that, The resin storage tank is provided with an overflow port, and a return pipeline is provided between the overflow port and the storage tank.

5. The ion exchanger unloading system according to claim 4, characterized in that, The overflow outlet is located in the upper middle part of the resin storage tank, and a screen is provided at the overflow outlet.

6. The ion exchanger unloading system according to claim 1, characterized in that, The infusion assembly further includes a first switching valve, which is disposed on the infusion line and located between the infusion pump and the second chamber; the aspiration assembly further includes a second switching valve, which is disposed on the aspiration line and located between the first chamber and the aspiration pump. And / or, the suction pump is configured as a diaphragm pump.

7. The ion exchanger unloading system according to claim 1, characterized in that, The first chamber is located above the second chamber in the height direction of the ion exchanger, the resin storage tank is located above the ion exchanger, and a resin delivery pipeline is provided between the resin storage tank and the first chamber of the ion exchanger.

8. The ion exchanger unloading system according to claim 7, characterized in that, A third switching valve is provided on the resin delivery pipeline, and a level gauge is provided on the ion exchanger. The level gauge is used to monitor the height change of the resin material in the reaction chamber, and the third switching valve is used to control the opening and closing of the resin delivery pipeline according to the height change of the resin material collected by the level gauge.

9. An ion exchange system, characterized in that, The system includes a feed storage bin, a feed pipeline, a discharge storage bin, a discharge pipeline, and an ion exchanger unloading system as described in any one of claims 1 to 8. The two ends of the feed pipeline are connected to the feed storage bin and the first chamber, and the two ends of the discharge pipeline are connected to the second chamber and the discharge storage bin.

10. The ion exchange system according to claim 9, characterized in that, The feed pipeline is equipped with a feed pump and a fourth switch valve. The discharge pipeline is equipped with a discharge pump and a fifth switch valve.

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