Integrated multi-tank integrated compact ion exchanger structure

Abstract

The application discloses a compact ion exchanger structure integrated with multiple tanks, which comprises a whole pressure-bearing shell, three sets of upper top cover assemblies, three sets of lower top cover assemblies and resin adding pipe sealing assemblies. Three resin containers are integrated in the shell and arranged in parallel and independently. Each resin container is respectively provided with a medium inlet and outlet, a resin adding pipe, a resin discharging pipe and a grating filter. The structure integrates multiple ion exchange tanks into a single device, which can reduce the volume of the device, external pipelines and potential leakage points, and is convenient for resin filling, replacement and filter maintenance, and improves the integration, sealing reliability and maintainability of a nuclear reactor primary loop purification device.

Description

Technical Field

[0001] This application belongs to the field of nuclear engineering equipment technology, specifically relating to an integrated multi-tank compact ion exchanger structure, and more particularly to a nuclear safety grade ion exchange device for purifying the primary loop coolant of a nuclear reactor, which integrates multiple resin containers within the same pressure boundary. Background Technology

[0002] During long-term operation, the primary coolant in a nuclear reactor may contain corrosion products, soluble ions, radionuclides, and other impurities. To control the chemical properties and radioactivity levels of the coolant, an ion exchanger is typically installed in the primary coolant purification system. Ion exchange resins are used to remove anionic and cationic impurities from the coolant, thereby maintaining the quality of the reactor coolant water and reducing corrosion and radioactive deposition in system equipment.

[0003] Existing ion exchange systems typically employ multiple discrete exchange tanks, each equipped with its own pressure-bearing shell, inlet and outlet pipelines, resin filling and discharge interfaces, valves, and supporting structure. These tanks are then connected in parallel or series via external piping to form a purification system. While this structure allows for the configuration of different types of resin beds, it results in a large number of devices, a large overall footprint, and complex external piping, which is not conducive to the compact layout of microreactors, small modular reactors, and other space-constrained nuclear power plants.

[0004] The discrete structure also results in more flange, clamp, and sealing connection modules. For nuclear-grade equipment handling primary loop radioactive media, the increased number of connection interfaces will correspondingly increase the potential leakage points; complex external piping may also generate large local stresses under vibration, impact, or seismic loads, affecting the integrity of pressure boundaries and the reliability of system operation.

[0005] In terms of maintenance and resin replacement, traditional multi-tank structures require the separate isolation and disassembly of multiple units and their associated piping, resulting in a significant workload for on-site installation and leak detection. The increased number of disassemblies not only prolongs system downtime but may also increase the working time and radiation exposure risk for personnel in a radioactive environment. For nuclear power plants with limited space, the layout of large flanges, lifting equipment, and disassembly access routes is also significantly restricted.

[0006] Furthermore, differences in the length and resistance of external pipelines across multiple exchange tanks can easily lead to uneven flow distribution in parallel branches, causing resin overload in some areas and underutilization in others. Insufficient volume margin during resin backwashing or expansion can also affect resin loosening, impurity removal, and bed recovery. If filters cannot balance resin retention capacity and ease of disassembly and inspection, resin particle loss, localized blockage, or maintenance difficulties may occur.

[0007] Therefore, it is necessary to provide an integrated, multi-tank compact ion exchanger structure that integrates multiple independent resin containers within the same nuclear safety-grade pressure boundary, reducing the number of equipment and external pipelines. Through independent media inlet and outlet, resin addition and discharge interfaces, and a detachable filter structure, it takes into account compact layout, sealing reliability, flow distribution, resin utilization rate, and ease of maintenance. Summary of the Invention

[0008] The purpose of this application is to provide an integrated, multi-tank compact ion exchanger structure to solve the problems of large space occupation, numerous external connections and potential leakage points, complex maintenance and operation, and difficulty in coordinating the flow rate and utilization rate of parallel resin beds in existing discrete ion exchanger equipment, and to improve the integration, pressure boundary reliability and maintainability of nuclear reactor primary loop purification equipment.

[0009] The technical solution to achieve the purpose of this application is as follows: This application provides an integrated multi-tank compact ion exchanger structure, including a shell assembly, three sets of upper top cover assemblies disposed on the top of the shell assembly, three sets of lower top cover assemblies disposed on the bottom of the shell assembly and corresponding one-to-one with the three sets of upper top cover assemblies, and a resin addition tube sealing assembly disposed at the upper top cover assembly. The shell assembly is an integral pressure-bearing shell, and three independent resin containers are integrated inside the shell assembly. The three resin containers are arranged in parallel within the same pressure-bearing boundary. Each set of upper top cover assemblies is provided with a medium inlet pipe and a resin addition pipe that are connected to the corresponding resin container, and each set of lower top cover assemblies is provided with a medium outlet pipe and a resin discharge pipe that are connected to the corresponding resin container. Both the upper top cover assembly and the lower top cover assembly are equipped with grate filters, so that the medium to be purified enters the corresponding resin container through the medium inlet pipe, comes into contact with the resin bed, and is discharged through the grate filter and the medium outlet pipe.

[0010] Optionally, the shell assembly includes a cylinder formed by forging, the cylinder having a seamless longitudinal weld structure and serving as a nuclear safety-grade pressure-bearing boundary, and the effective volume of the cylinder above the distribution plate being greater than the resin filling volume of the corresponding resin container.

[0011] Optionally, the three resin containers include two mixed beds and one cation bed; the mixed beds are filled with nuclear-grade hydroxyl anion resin and nuclear-grade lithium cation resin, and the cation bed is filled with nuclear-grade hydrogen cation resin.

[0012] Optionally, each set of the top cover assembly includes a top cover, a distribution cylinder and a distribution plate, the medium inlet pipe is arranged along the central axis of the corresponding top cover and welded to the top cover, and the resin addition pipe is arranged along the side axis of the corresponding top cover and sealed by a flange.

[0013] Optionally, each set of the lower top cover assembly is provided corresponding to the bottom of one of the resin containers, and the medium outlet pipe and the resin discharge pipe are both butt-welded to the corresponding lower top cover assembly.

[0014] Optionally, the resin addition tube sealing assembly includes a sealing tube seat, a sealing block, a graphite gasket, a sealing pressure plate, and bolt fasteners. The graphite gasket is disposed between the sealing block and the sealing pressure plate, and the bolt fasteners press the sealing pressure plate onto the sealing tube seat.

[0015] Optionally, the bolt fastener includes a stud, a flat washer, and a nut. The stud passes through the sealing pressure plate and is connected to the sealing tube seat. The nut presses the sealing pressure plate together with the flat washer.

[0016] Optionally, the grate filter includes a filter connector, a filter support plate, a lower filter plate, a first filter element, a second filter element, a third filter element, a fourth filter element, a first filter rod, a second filter rod, a third filter rod, an upper filter plate, an M16 nut, an M6 nut, a filter gasket, and an M8 nut. The first filter element, the second filter element, the third filter element, and the fourth filter element are stacked between the lower filter plate and the upper filter plate and are fastened by the first filter rod, the second filter rod, the third filter rod, and the corresponding nuts.

[0017] Optionally, the first filter, the second filter, the third filter, and the fourth filter include multiple filter elements stacked sequentially along the axial direction, and the final filtration gap after stacking the first filter, the second filter, the third filter, and the fourth filter is no greater than 0.15 mm.

[0018] Optionally, the grate filter is detachably connected to the corresponding upper or lower cover assembly, and can be installed or removed as a whole with the upper or lower cover assembly.

[0019] Optionally, a sealing ring, a positioning ring, mounting bolts, and a shear ring are provided between the housing assembly and the upper cover assembly. The sealing ring is used to form an axial seal, the positioning ring is used to limit the assembly position of the upper cover assembly, and the shear ring is used to withstand the shear load between the upper cover assembly and the housing assembly.

[0020] Optionally, the medium inlet pipe, the medium outlet pipe, and the resin discharge pipe are welded to the system pipeline, and the resin addition port of the resin addition pipe is sealed with a flange.

[0021] The beneficial technical effects of this application are as follows: The integrated multi-tank compact ion exchanger structure provided in this application includes an integral pressure-bearing shell assembly, three sets of upper top cover assemblies located on top of the shell assembly, three sets of lower top cover assemblies located at the bottom of the shell assembly and corresponding one-to-one with the three sets of upper top cover assemblies, and a resin addition pipe sealing assembly. The shell assembly integrates three independent, parallel-arranged resin containers within the same pressure-bearing boundary. Each resin container is equipped with a media inlet pipe, a media outlet pipe, a resin addition pipe, a resin discharge pipe, and a grate filter. Through this structure, multiple ion exchange tanks that were originally arranged separately are integrated into a single unit, significantly reducing the number of devices, support structures, and external connection pipelines, lowering the overall volume and weight, and adapting to microreactors. In space-constrained scenarios such as nuclear reactors and small modular reactors, the integrated nuclear safety-grade pressure vessel and welded system interfaces reduce potential leakage points and improve the reliability of radioactive media containment. The three resin containers maintain independent functions and flow paths, allowing for separate configurations of mixed beds and cation beds, and improving resin bed utilization. The top and bottom grate filters can evenly distribute the medium and trap resin particles. Their detachable structure facilitates overall maintenance along with the top cover. The resin addition pipe sealing assembly and resin discharge pipe facilitate resin filling, replacement, and maintenance, thereby shortening downtime and disassembly time, reducing personnel operation and radiation risks, and improving the engineering integration, operational safety, and maintainability of the primary coolant purification system. Attached Figure Description

[0022] Figure 1 is a schematic diagram of the integrated multi-tank compact ion exchanger structure provided in this application; Figure 2 is a schematic diagram of the resin addition tube sealing assembly provided in this application; Figure 3 is a schematic diagram of the upper cover assembly structure provided in this application; Figure 4 is a schematic diagram of the grate filter structure provided in this application.

[0023] In the diagram: 1-Resin addition tube sealing assembly, 2-Sealing ring, 3-Positioning ring, 4-Mounting bolt, 5-Shear ring, 6-Upper top cover assembly, 7-Housing assembly, 8-Lower top cover assembly, 9-Media outlet pipe, 10-Resin discharge pipe, 11-Sealing tube seat, 12-Sealing support block, 13-Graphite gasket, 14-Sealing pressure plate, 15-Stud, 16-Flat washer, 17-Nut, 18-Upper top cover, 19-Resin addition tube, 20- 21-Distribution cylinder, 22-Distribution plate, 23-Grate filter, 24-Filter connector, 25-Filter support plate, 26-Lower filter plate, 27-First filter element, 28-Second filter element, 29-Third filter element, 30-First filter rod, 31-Second filter rod, 32-Third filter rod, 33-Upper filter plate, 34-M16 nut, 35-M6 nut, 36-Filter gasket, 37-M8 nut. Detailed Implementation

[0024] To enable those skilled in the art to better understand this application, the technical solution of this application is clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the following specific embodiments are only some embodiments of this application and are not intended to limit the scope of protection of this application. Equivalent substitutions, modifications, or improvements made by those skilled in the art based on the content of this application without departing from the concept of this application should all fall within the scope of protection of this application.

[0025] The directional or positional terms such as "upper," "lower," "top," "bottom," "axial," and "radial" used in this application are, in accordance with... Figure 1 The equipment layout direction and the central axis of the corresponding components shown are for reference only, and are used to illustrate the relative positional relationship between the components. They do not constitute a limitation on the actual installation posture of the equipment.

[0026] As shown in Figures 1 to 4, this embodiment provides an integrated, multi-tank, compact ion exchanger structure. This ion exchanger can be installed in the primary loop purification system of a nuclear reactor to receive the reactor coolant to be purified and remove ionic impurities and radionuclides from the coolant using ion exchange resin filled in a resin container. The equipment is generally vertically arranged and can be installed using suspension supports, bracket supports, or other support methods connected to the compartment structure.

[0027] The ion exchanger includes a shell assembly 7, three sets of upper top cover assemblies 6, three sets of lower top cover assemblies 8, and a resin addition tube sealing assembly 1. The three sets of upper top cover assemblies 6 are arranged side by side at the top along the transverse direction of the shell assembly 7, and the three sets of lower top cover assemblies 8 are located at the bottom, corresponding one-to-one with the three sets of upper top cover assemblies 6 and the three resin containers. Each set of upper top cover assemblies 6, the corresponding resin container, and the corresponding lower top cover assembly 8 together form a relatively independent media purification flow path.

[0028] Figure 1 shows representative annotations for only some of the repetitive components. In practical applications, each resin addition tube 19 can be equipped with a corresponding resin addition tube sealing assembly 1. The same components in the three purification flow paths can adopt the same or similar structural dimensions, or they can be designed separately according to the type of resin, the processing flow rate, and the resistance requirements.

[0029] Shell assembly 7 is an integral pressure-bearing shell, forming three independent elongated cylindrical resin containers within the same external pressure-bearing boundary. The three resin containers are separated from each other by shell material or partition walls, preventing the medium and resin in one flow path from directly entering adjacent flow paths. The three resin containers are arranged in parallel and can be put into operation simultaneously, or isolated, put into operation, or maintained separately in conjunction with system valves.

[0030] In one embodiment, the shell assembly 7 is machined from a single forging. The forged shell body has no longitudinal welds, reducing manufacturing defects from long welds and in-service inspection workload, and improving the continuity of the nuclear safety grade pressure boundary. The shell assembly 7 may be made of nuclear-grade austenitic stainless steel, such as 026Cr18Ni12Mo2N, or other materials capable of withstanding high temperatures, high pressures, boron-containing water, and radioactive environments. Materials, forging, heat treatment, welding, and non-destructive testing may be carried out in accordance with RCC-M or applicable nuclear-grade equipment design and manufacturing specifications.

[0031] Each resin container has an effective volume greater than the normal filling volume of the corresponding resin, thus creating an expansion margin in the upper part of the resin bed or within the effective space defined by the distribution plate 21. This expansion margin can accommodate the volume increase of the resin during backwashing, temperature changes, and changes in water absorption, preventing over-compaction of the resin bed and providing space for media redistribution. The specific ratio of effective volume to filling volume can be determined based on the resin type, design flow rate, and backwash expansion rate.

[0032] In this embodiment, the three resin containers include two mixed beds and one cation bed. Each mixed bed can be filled with nuclear-grade hydroxyl anion resin and nuclear-grade lithium cation resin to simultaneously remove anionic and cationic impurities from the coolant; the cation bed can be filled with nuclear-grade hydrogen cation resin to remove specific cationic contaminants. The combination of resin beds is not limited to the above-described form, and other nuclear-grade ion exchange resins can also be configured according to the primary loop water chemistry control scheme.

[0033] As shown in Figure 3, each set of upper cover assembly 6 includes an upper cover 18, a distribution cylinder 20, a distribution plate 21, and a grate filter 22. The media inlet pipe is arranged along the central axis of the upper cover 18 and welded to the upper cover 18 to form a stable pressure-bearing inlet. The resin addition pipe 19 is arranged along the side axis of the upper cover 18, with its lower end communicating with the corresponding resin container and its upper end forming an openable resin addition port.

[0034] The distribution cylinder 20 and distribution plate 21 are located on the side of the top cover 18 facing the resin container. After the medium to be purified enters through the medium inlet pipe, it is guided by the distribution cylinder 20 and dispersed by the distribution plate 21 and the upper grate filter 22, ensuring a relatively uniform flow velocity distribution before entering the resin bed. The distribution plate 21 can be provided with multiple flow holes, guide holes, or flow channels; the pore size, opening ratio, and distribution pattern can be determined according to the design flow rate and allowable pressure drop.

[0035] A sealing ring 2, a positioning ring 3, mounting bolts 4, and a shear ring 5 are provided between the housing assembly 7 and the upper cover assembly 6. The sealing ring 2 is located between the corresponding sealing surfaces and forms an axial seal under the preload provided by the mounting bolts 4. The positioning ring 3 restricts the radial or axial assembly position of the upper cover assembly 6, ensuring alignment of the media inlet pipe, resin addition pipe 19, and internal filter components with the resin container. The shear ring 5 is positioned at the mating point between the housing assembly 7 and the upper cover assembly 6 to transfer shear loads generated by the equipment's own weight, pipeline loads, vibration, or seismic forces, reducing the degree to which the seals and mounting bolts 4 directly bear lateral loads.

[0036] As shown in Figure 2, the resin addition tube sealing assembly 1 includes a sealing tube seat 11, a sealing block 12, a graphite gasket 13, a sealing pressure plate 14, studs 15, a flat washer 16, and a nut 17. The sealing tube seat 11 is connected to or integrally formed with the addition port of the resin addition tube 19. The sealing block 12 is disposed at the opening of the sealing tube seat 11, and the graphite gasket 13 is disposed between the sealing block 12 and the sealing pressure plate 14. Multiple studs 15 pass through the sealing pressure plate 14 and are connected to the sealing tube seat 11. The nut 17 applies a preload force to the sealing pressure plate 14 through the flat washer 16, causing the graphite gasket 13 to be compressed and form a seal.

[0037] The graphite gasket 13 is temperature-resistant, radiation-resistant, and adaptable to minor deformations of the sealing surface, making it suitable for nuclear-grade radioactive media environments. When resin filling or replenishment is required, after system isolation, depressurization, and confirmation of radiation protection conditions, the nut 17, flat washer 16, and sealing plate 14 can be removed, the sealing support block 12 removed, and the resin filling port opened. After resin filling, the components are reassembled in the prescribed order, and the seal integrity is confirmed through a preload check and leak test.

[0038] Each set of lower top cover assemblies 8 is located at the bottom of the corresponding resin container. The media outlet pipe 9 and the resin discharge pipe 10 are both butt-welded to the lower top cover assembly 8. The media outlet pipe 9 is used to return the media purified by the resin bed to the system, and the resin discharge pipe 10 is used to discharge resin when it fails or requires maintenance. The resin discharge pipe 10 may have a bend to accommodate space at the bottom of the equipment and the layout of system pipelines.

[0039] Both the upper cover assembly 6 and the lower cover assembly 8 are equipped with grate filters 22. The upper grate filter 22 is used to distribute the medium entering the resin bed and prevent resin from migrating towards the inlet; the lower grate filter 22 is used to support the resin bed, trap resin particles, and allow the purified medium to enter the medium outlet pipe 9. The upper and lower filters can adopt the same basic structure, and the filter thickness, gap, and support method can be adjusted according to the flow direction and load requirements.

[0040] As shown in Figure 4, the grate filter 22 includes a filter inlet 23, a filter support plate 24, a lower filter plate 25, a first filter element 26, a second filter element 27, a third filter element 28, a fourth filter element 29, a first filter pull rod 30, a second filter pull rod 31, a third filter pull rod 32, an upper filter plate 33, an M16 nut 34, an M6 nut 35, a filter gasket 36, and an M8 nut 37. The filter inlet 23 forms the connection channel between the filter and the corresponding media pipeline or top cover flow channel. The filter support plate 24, the lower filter plate 25, and the upper filter plate 33 form a filter element stacking and load transfer frame.

[0041] The first filter element 26, the second filter element 27, the third filter element 28, and the fourth filter element 29 may represent filter element groups with different thicknesses, outer diameters, inner diameters, tooth profiles, or flow channel structures, respectively, with each filter element alternating or stacked in layers along the axial direction. Annular or radial filtration gaps are formed between adjacent surfaces of the filter elements, with the final filtration gap not exceeding 0.15 mm to allow coolant passage and prevent the main resin particles from being lost with the medium. The filtration gap can be further reduced depending on the particle size distribution of the resin used.

[0042] Multiple filter elements are secured between the lower filter plate 25 and the upper filter plate 33 by a first filter rod 30, a second filter rod 31, and a third filter rod 32, along with corresponding nuts. A filter gasket 36 is used to adjust the assembly clearance and preload. M16 nuts 34, M6 nuts 35, and M8 nuts 37 mate with their respective connection points to ensure the filter maintains structural stability when subjected to resin weight, media pressure differential, and flow-induced vibration.

[0043] The grate filter 22 is detachably connected to either the upper cover assembly 6 or the lower cover assembly 8. When the corresponding cover assembly is removed, the grate filter 22 can be removed as a whole, allowing for external inspection of the filter element gaps, clogging, corrosion, and tightness. It also facilitates cleaning or replacement of the filter elements. Compared to filters fixed deep within the housing, this structure reduces maintenance operations inside the elongated resin container.

[0044] The medium inlet pipe, medium outlet pipe 9, and resin discharge pipe 10 can be welded to the system piping to reduce the number of detachable interfaces at the pressure boundary of the high-temperature, high-pressure radioactive medium. Since the resin addition pipe 19 needs to be opened periodically, its inlet is fitted with a flange or a detachable seal formed by the resin addition pipe sealing assembly 1. The system piping can be equipped with isolation valves, flow regulating devices, and sampling interfaces to achieve independent control of the three resin containers.

[0045] During ion exchanger operation, the media to be purified enters the corresponding upper cover assembly 6 through each media inlet pipe. After being evenly distributed by the distribution cylinder 20, distribution plate 21, and upper grate filter 22, it enters the resin bed. The media flows axially along the resin container and makes full contact with the resin, where impurity ions are exchanged or adsorbed by the resin. The purified media enters the media outlet pipe 9 through the lower grate filter 22 and returns to the primary loop purification system. The three flow paths can operate at the same flow rate according to system requirements, or different flow rates can be achieved through branch adjustment.

[0046] During resin filling, resin and replacement fluid can be delivered to the corresponding resin container through the resin addition pipe 19. When resin is discharged or replaced, the spent resin can be discharged through the resin discharge pipe 10, and then rinsed and refilled through the resin addition pipe 19. Since the three resin containers are independent of each other, individual resin containers can be isolated for maintenance when the system design allows, while the remaining resin containers continue to perform some of the purification functions, thereby improving system availability.

[0047] After the equipment is manufactured, dimensional inspection, non-destructive testing of welds, pressure testing, helium mass spectrometry leak detection, or other applicable sealing tests can be performed in sequence. For the grate filter 22, the filter element stacking order, final filtration gap, and fastener anti-loosening status should be checked; for the top cover assembly 6, the compression of the sealing ring 2, the fit of the positioning ring 3, and the assembly of the shear ring 5 should be checked; for the resin addition tube sealing assembly 1, the surface of the graphite gasket 13 and the bolt preload status should be checked.

[0048] Example 1: This example is applied to a primary loop purification system for a microreactor. The shell assembly 7 is machined from 026Cr18Ni12Mo2N nuclear-grade austenitic stainless steel forgings, and the equipment uses a vertical suspension support. Of the three resin containers, two serve as mixed beds, filled with nuclear-grade hydroxyl-type anion resin and nuclear-grade lithium-type cation resin; the other serves as a cation bed, filled with nuclear-grade hydrogen-type cation resin. The medium inlet and outlet are welded to the system piping, and the resin addition port is sealed with a graphite gasket. This structure enables the integration of the functions of three traditional exchange tanks within a confined space, reducing the number of external pipelines and supports.

[0049] Example 2: This example applies to the primary loop purification system of a small modular reactor. The shell assembly 7 can be formed into three independent resin containers using integral forging followed by deep hole machining, near-net-shape manufacturing, or an integrated molding process that meets nuclear-grade quality assurance requirements. Each upper top cover assembly 6 is equipped with a central medium inlet pipe and a side resin addition pipe 19, and each lower top cover assembly 8 is equipped with a medium outlet pipe 9 and a resin discharge pipe 10. During operation, the distribution plate 21 and the grate filter 22 ensure uniform coolant flow through the resin bed; when replacing the resin, only the corresponding resin addition pipe sealing assembly 1 and resin discharge pipe 10 need to be opened, without disassembling the main system's welded pressure-bearing boundaries.

[0050] With the above structure, a single ion exchanger integrates three independent resin containers within a single pressure-bearing boundary, achieving equipment compactness while maintaining the independent function of each resin bed. The integral shell, welded system interfaces, top cover seal, and shear force transmission structure together improve pressure resistance and vibration resistance reliability, while the removable filter and resin addition and discharge interfaces enhance the convenience of maintenance and resin replacement.

[0051] The present application has been described above with reference to the accompanying drawings and specific embodiments, but the present application is not limited to the specific embodiments described above. The number and arrangement of resin containers, resin types, shell manufacturing processes, sealing methods, filter element structures, pipeline connection methods, and inspection methods not described in detail in this application can all be implemented using existing technologies in the art without departing from the concept of this application.

Claims

1. A compact ion exchanger structure integrating multiple tanks, characterized in that, It includes a housing assembly (7), three sets of upper top cover assemblies (6) disposed on the top of the housing assembly (7), three sets of lower top cover assemblies (8) disposed on the bottom of the housing assembly (7) and corresponding to the three sets of upper top cover assemblies (6), and a resin addition tube sealing assembly (1) disposed on the upper top cover assembly (6). The shell assembly (7) is an integral pressure-bearing shell. Three independent resin containers are integrated inside the shell assembly (7). The three resin containers are arranged in parallel within the same pressure-bearing boundary. Each set of upper top cover assemblies (6) is provided with a medium inlet pipe and a resin addition pipe (19) communicating with the corresponding resin container, and each set of lower top cover assemblies (8) is provided with a medium outlet pipe (9) and a resin discharge pipe (10) communicating with the corresponding resin container. Both the upper top cover assembly (6) and the lower top cover assembly (8) are equipped with grate filters (22) so that the medium to be purified enters the corresponding resin container through the medium inlet pipe, and after contacting the resin bed, it is discharged through the grate filter (22) and the medium outlet pipe (9).

2. The integrated multi-tank compact ion exchanger structure according to claim 1, characterized in that, The shell assembly (7) includes a cylinder formed by forging, the cylinder having a no longitudinal weld seam structure and serving as a nuclear safety grade pressure-bearing boundary, and the effective volume of the cylinder above the distribution plate (21) being greater than the resin filling volume of the corresponding resin container.

3. The integrated multi-tank compact ion exchanger structure according to claim 1, characterized in that, The three resin containers include two mixed beds and one cation bed; the mixed beds are filled with nuclear-grade hydroxyl anion resin and nuclear-grade lithium cation resin, and the cation bed is filled with nuclear-grade hydrogen cation resin.

4. The integrated multi-tank compact ion exchanger structure according to claim 1, characterized in that, Each set of the top cover assembly (6) includes a top cover (18), a distribution cylinder (20) and a distribution plate (21). The medium inlet pipe is arranged along the central axis of the corresponding top cover (18) and welded to the top cover (18). The resin addition pipe (19) is arranged along the side axis of the corresponding top cover (18) and sealed by a flange.

5. The integrated multi-tank compact ion exchanger structure according to claim 1, characterized in that, Each set of the lower top cover assembly (8) is provided corresponding to the bottom of one of the resin containers, and the medium outlet pipe (9) and the resin discharge pipe (10) are butt-welded to the corresponding lower top cover assembly (8).

6. The integrated multi-tank compact ion exchanger structure according to claim 1, characterized in that, The resin addition tube sealing assembly (1) includes a sealing tube seat (11), a sealing block (12), a graphite gasket (13), a sealing pressure plate (14), and bolt fasteners. The graphite gasket (13) is disposed between the sealing block (12) and the sealing pressure plate (14), and the bolt fasteners press the sealing pressure plate (14) onto the sealing tube seat (11).

7. The integrated multi-tank compact ion exchanger structure according to claim 6, characterized in that, The bolt fastener includes a stud (15), a flat washer (16) and a nut (17). The stud (15) passes through the sealing pressure plate (14) and is connected to the sealing tube seat (11). The nut (17) presses the sealing pressure plate (14) through the flat washer (16).

8. The integrated multi-tank compact ion exchanger structure according to claim 1, characterized in that, The grate filter (22) includes a filter connector (23), a filter support plate (24), a filter lower plate (25), a first filter element (26), a second filter element (27), a third filter element (28), a fourth filter element (29), a first filter rod (30), a second filter rod (31), a third filter rod (32), a filter upper plate (33), an M16 nut (34), an M6 nut (35), a filter gasket (36), and an M8 nut (37). The first filter element (26), the second filter element (27), the third filter element (28), and the fourth filter element (29) are stacked between the filter lower plate (25) and the filter upper plate (33) and are fastened by the first filter rod (30), the second filter rod (31), the third filter rod (32), and the corresponding nuts.

9. The integrated multi-tank compact ion exchanger structure according to claim 8, characterized in that, The first filter (26), the second filter (27), the third filter (28) and the fourth filter (29) include multiple filter sheets stacked sequentially along the axial direction. The final filtration gap after the first filter (26), the second filter (27), the third filter (28) and the fourth filter (29) are stacked is no greater than 0.15 mm.

10. The integrated multi-tank compact ion exchanger structure according to claim 1 or 8, characterized in that, The grate filter (22) is detachably connected to the corresponding upper cover assembly (6) or lower cover assembly (8), and can be installed or removed as a whole with the upper cover assembly (6) or the lower cover assembly (8).

11. The integrated multi-tank compact ion exchanger structure according to claim 1, characterized in that, A sealing ring (2), a positioning ring (3), a mounting bolt (4), and a shear ring (5) are provided between the housing assembly (7) and the upper cover assembly (6). The sealing ring (2) is used to form an axial seal, the positioning ring (3) is used to restrict the assembly position of the upper cover assembly (6), and the shear ring (5) is used to bear the shear load between the upper cover assembly (6) and the housing assembly (7).

12. The integrated multi-tank compact ion exchanger structure according to claim 1, characterized in that, The medium inlet pipe, the medium outlet pipe (9) and the resin discharge pipe (10) are welded to the system pipeline, and the resin addition port of the resin addition pipe (19) is sealed with a flange.

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