A multi-kettle series rotary chain type magnetic separation radioactive wastewater treatment system

Abstract

This invention belongs to the technical field of wastewater treatment and discloses a multi-reactor series rotary chain magnetic separation radioactive wastewater treatment system. The system includes a magnetic separation device and multiple reaction vessels. The magnetic separation device comprises an adsorption zone and a separation zone. The adsorption zone includes a rotary chain, multiple metal grids mounted on the rotary chain, and an adsorption zone shell located outside the rotary chain. The rotary chain rotates along the axial direction of the adsorption zone. Permanent magnets are provided on the adsorption zone shell and / or the separation zone shell. Multiple scrapers are provided along the axial direction of the separation zone. The adsorption zone and separation zone partially overlap, and the scrapers contact the metal grids during rotation. The permanent magnets magnetize the metal grids, causing them to adsorb magnetic adsorbents. The rotary chain drives the metal grids to move, and the adsorbents are scraped off and removed at the overlap of the adsorption and separation zones by the scrapers. This application can achieve real-time adsorption and separation of waste in wastewater.

Description

Technical Field

[0001] This invention belongs to the technical field of wastewater treatment, and more specifically, relates to a multi-tank series rotary chain magnetic separation radioactive wastewater treatment system. Background Technology

[0002] As people increasingly value environmental protection, nuclear power generation is becoming more widespread. However, even normally operating nuclear power plants still face the problem of radioactive wastewater treatment. Common methods mainly involve concentration and enrichment followed by cement solidification, or long-term decay treatment. Concentration and enrichment can be achieved through chemical and physical methods, specifically using adsorbents for concentration and separation. Recent research has made significant progress using adsorbents based on Fe3O4 or iron powder. These adsorbents not only have fast adsorption rates and good effects, but also possess ferromagnetism, allowing them to be easily separated by magnetic fields.

[0003] Magnetic separation technology is a mature technology commonly used in metallurgy and mining. The fact that ferromagnetic adsorbents can be easily separated by magnetic fields makes magnetic separation technology applicable to the water treatment industry. Furthermore, magnetic separation technology offers fast separation speed and good results, thus solving the time-consuming and labor-intensive problems in conventional radioactive wastewater treatment. However, currently popular magnetic separation devices are not highly efficient in utilizing the magnetic field, resulting in significant energy waste in the coils, and they cannot achieve integrated adsorption and separation, severely impacting the efficiency of magnetic separation. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a multi-tank series rotary chain magnetic separation radioactive wastewater treatment system, which solves the problems of real-time adsorption and separation and energy waste in existing magnetic separation technologies.

[0005] To achieve the above objectives, according to one aspect of the present invention, a multi-reactor series rotary chain magnetic separation radioactive wastewater treatment system is provided. This system uses magnetic adsorbents to remove radionuclides from wastewater and includes a magnetic separation device and multiple reactors connected in series. The magnetic separation device includes an adsorption zone and a separation zone. The adsorption zone includes a rotary chain, multiple metal grids mounted on the rotary chain, and an adsorption zone shell located outside the rotary chain. The rotary chain rotates along the axial direction of the adsorption zone. Permanent magnets are provided on the adsorption zone shell and / or the separation zone shell. Multiple scrapers are provided along the axial direction of the separation zone. The adsorption zone and the separation zone partially overlap, and the scrapers contact the metal grids during rotation. The permanent magnets magnetize the metal grids, causing them to adsorb metal ions from the wastewater. The rotary chain drives the metal grids to move, and the ions are scraped off and removed at the overlap of the adsorption zone and the separation zone by the scrapers.

[0006] Preferably, the metal grid includes multiple fan-shaped mesh structures, each fan shape includes multiple skeletons, each skeleton is arc-shaped, and the multiple skeletons are arranged to protrude towards the root of the fan shape.

[0007] Preferably, the diameter of the skeleton is 1 to 2 mm.

[0008] Preferably, the plurality of metal grids are arranged at equal intervals on the rotary chain.

[0009] Preferably, multiple scraper blades are arranged in a spiral pattern along the axial direction of the separation zone; the pitch of the spirally arranged scraper blades is the same as the distance between two adjacent metal grids.

[0010] Preferably, the permanent magnets are arranged in a Heilbeck array.

[0011] Preferably, the reactor is equipped with a stirring paddle located at the bottom of the reactor. The stirring paddle comprises multiple layers of blades along the radial direction, with adjacent layers of blades rotating in opposite directions.

[0012] Preferably, the impeller comprises two layers of blades, with forward-rotating blades arranged at 0 to 2 / 3 of the radial direction and reverse-rotating blades arranged at 2 / 3 to 1.

[0013] Preferably, the number of reaction vessels is two.

[0014] In summary, compared with the prior art, the multi-tank series rotary chain magnetic separation radioactive wastewater treatment system provided by this invention has the following advantages:

[0015] 1. This application employs a multi-stage reactor. First, a magnetic adsorbent is used to remove radioactive elements from the wastewater. Then, the water flow carries the magnetic adsorbent and impacts a metal grid. The metal grid, magnetized by a magnet, has the ability to adsorb the magnetic adsorbent. After adsorbing the magnetic adsorbent, the metal grid rotates within the magnetic separation device via a chain, reaching a scraping zone. In this zone, the adsorbent on the metal grid is scraped off and collected in a lower container. Meanwhile, the water flows smoothly through the metal grid into different collectors, significantly improving the removal efficiency of radioactive elements, reaching over 79%. Real-time adsorption and separation are achieved, and the adsorbent can be recovered promptly.

[0016] 2. The impeller blades in this application are designed to rotate in different directions, which can generate water flow in two directions in the reactor, enhancing turbulence and mixing in the reactor, while avoiding the use of stationary blades, which may cause solid materials to accumulate in corners.

[0017] 3. Within the scraper area, scrapers are installed on a spiral rotating device. The pitch of the rotating device is the same as the spacing between adjacent metal grids, ensuring that the adsorbent on the metal grids is always scraped.

[0018] 4. Rectangular permanent magnets arranged in a Hellbeck array are placed around the magnetic adsorption area. The interaction of the magnets can generate a strong magnetic field in the magnetic adsorption area to magnetize the metal grid. The magnetic field formed by the Hellbeck array is perpendicular to the metal grid, which has the best magnetization effect on the metal grid. Attached Figure Description

[0019] Figure 1 This is a perspective view of the multi-tank series rotary chain magnetic separation radioactive wastewater treatment system according to an embodiment of this application;

[0020] Figure 2 This is a half-sectional view of the multi-tank series rotary chain magnetic separation radioactive wastewater treatment system according to an embodiment of this application;

[0021] Figure 3 This is a schematic diagram of the magnetic separation device according to an embodiment of this application;

[0022] Figure 4 This is a top view of the magnetic separation device according to an embodiment of this application;

[0023] Figure 5 This is a schematic diagram of the metal grid of the magnetic separation device according to an embodiment of this application;

[0024] Figure 6 This refers to the stirring paddle in this application embodiment;

[0025] Figure 7 This is a schematic diagram of the magnetic field distribution of a permanent magnet disposed in the shell of the adsorption region according to an embodiment of this application;

[0026] Figure 8 This is a schematic diagram of the magnetic field distribution of permanent magnets in the adsorption zone shell and the separation zone shell according to an embodiment of this application;

[0027] Figure 9 This is a schematic diagram of the magnetic field distribution of a permanent magnet in the housing of the separation zone according to an embodiment of this application;

[0028] Figure 10 This refers to the magnetic field adsorption force when a permanent magnet is provided in the shell of the adsorption region according to an embodiment of this application;

[0029] Figure 11 This refers to the magnetic field adsorption force when permanent magnets are provided in the adsorption zone shell and the separation zone shell in this embodiment of the application;

[0030] Figure 12 This refers to the magnetic field adsorption force when a permanent magnet is provided in the shell of the separation zone according to an embodiment of this application;

[0031] Figure 13 The radionuclide Co in the embodiments of this application 2+ The removal effect image, where (a) is Co 2+ The relationship between concentration and time, (b) is the Co concentration. 2+ The relationship between removal rate and time.

[0032] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0033] 1-Motor; 2-Cover; 3-First-stage reactor; 4-Support frame; 5-Pipeline; 6-Second-stage reactor; 7-Valve; 8-Magnetic separation device; 9-Agitator; 81-Inlet; 82-Adsorption zone; 83-Metal grid; 84-Adsorption zone shell; 85-Outlet; 86-Scraper; 87-Separation zone; 88-Separation zone shell; 89-Magnetic particle separation port. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0035] This invention provides a multi-tandem rotary chain magnetic separation radioactive wastewater treatment system, which includes a magnetic separation device and multiple reactors connected in series, such as... Figure 1 and Figure 2 As shown, the magnetic separation device includes an adsorption zone 82 and a separation zone 87, with the following specific structure.

[0036] like Figure 3 As shown, the adsorption zone 82 includes a rotating chain, a plurality of metal grids 83 disposed on the rotating chain, and an adsorption zone housing 84 disposed outside the rotating chain. The rotating chain rotates along the axial direction of the adsorption zone. The adsorption zone housing 84 and / or the separation zone housing 88 are provided with permanent magnets. The upper part of the adsorption zone 82 is provided with a water inlet 81, and the lower part is provided with a water outlet 85.

[0037] The separation zone 87 is provided with multiple scraper strips 86 along the axial direction. The adsorption zone and the separation zone partially overlap. During the rotation, the scraper strips 86 contact the metal grid 83. The lower part of the separation zone 87 is provided with a magnetic particle separation port 89.

[0038] The permanent magnet magnetizes the metal grid 83, which then adsorbs metal ions in the wastewater. The rotating chain drives the metal grid 83 to move and is scraped off by the scraper 86 at the overlap of the adsorption zone and the separation zone.

[0039] In a further preferred embodiment, the metal grille 83 includes multiple fan-shaped mesh structures (such as...). Figure 4 and Figure 5 As shown, each sector comprises multiple skeletons, each skeleton being arc-shaped, with all skeletons protruding towards the root of the sector. Furthermore, the metal grid 83 is made of woven metal wire, distributed in an inverted U-shape around its perimeter, perpendicular to the magnetic field lines. This creates a larger magnetic field gradient within the metal surface space, increasing the adsorption force, allowing the metal grid 83 to effectively adsorb magnetic adsorbents. The metal mesh orientation of the metal grid 83 should be designed to ensure perpendicularity to the magnetic field lines, and the radius of the metal wires should neither be too small to lose the ability to attract magnetic adsorbents, nor too large to reduce the magnetic field gradient near the wires; ordinary iron wire of one to two millimeters is sufficient.

[0040] Multiple metal grids 83 are arranged at equal intervals on the rotary chain.

[0041] In a further preferred embodiment, the reactor is provided with a stirring paddle 9, which is located at the lower part of the reactor, preferably at about 2 / 3 of the reactor. The stirring paddle 9 includes multiple layers of blades in the radial direction, with adjacent layers of blades rotating in opposite directions.

[0042] In further optimized solutions, such as Figure 6 As shown, the stirring paddle 9 comprises two layers of blades, with forward-rotating blades positioned from 0 to 2 / 3 of the radial direction and counter-rotating blades positioned from 2 / 3 to 1. Therefore, during rotation, the water flow direction in the central region of the reactor is downward, while the water flow direction in the outer region is upward, and the volumetric flow rates are equal. This creates a circulating flow in the rz plane, thereby increasing turbulence within the reactor. Simultaneously, the overall rotation direction of the water flow within the reactor is consistent with the stirring direction, which can also create turbulence in the bottom pipes, preventing adsorbent precipitation within the pipes.

[0043] In a further preferred embodiment, a plurality of scraper blades 86 are arranged spirally in the axial direction of the separation zone 87. Within the scraper blade area, the scraper blades are mounted on a spiral rotating device, the pitch of which is the same as the spacing between adjacent metal grids, ensuring that the adsorbent on the metal grids is constantly scraped.

[0044] In a further preferred solution, such as Figures 7-9As shown, the permanent magnets are arranged in a square permanent magnet block in a Hellbeck array. This arrangement prevents iron powder from directly adhering to the wall surface while completing the magnetic separation process. The interaction of the magnets can generate a strong magnetic field in the magnetic adsorption area to magnetize the metal grid 83. The strength of the magnetic field should be designed to be sufficient to magnetize the metal grid without attracting the magnetic adsorbent on the inner wall of the magnetic adsorption area. In this embodiment, the distribution of the magnetic field is obtained through simulation calculations and expressed as the gradient of the magnetic scalar potential. The results show that the magnetic field is strongest at the edge and weakest in the middle, with a minimum of 1.5A. The forces acting on the magnetic material in the magnetic field are then analyzed, such as... Figures 10-12 As shown, with a gradient of 1 cm, the adsorption force of the magnetic field in the y direction is approximately 0.0069-0.0108 N (approximately 0.0086 N when a permanent magnet is placed only in the shell of the adsorption zone, approximately 0.0108 N when permanent magnets are placed in both the shell of the adsorption zone and the shell of the separation zone, and approximately 0.0069 N when a permanent magnet is placed only in the shell of the separation zone). The impact force caused by the water flow is approximately 0.003 N, so adsorption can be achieved. However, given that the magnetic adsorption and throttling effect in the middle part of the magnetic field is relatively weak, baffles can be added later to prevent the magnetic material from settling in the middle.

[0045] In a further preferred embodiment, there are two reactors: a first-stage reactor 3 and a second-stage reactor 6. The two reactors are supported by a support frame 4 and connected by a pipe 5, which connects the bottom of the first-stage reactor to the side of the second-stage reactor. The second reactor 6 is connected to a magnetic separation device 8 via a pipe, with a valve 7 installed on the connecting pipe. Due to the connecting device, the liquid levels in both reactors are the same. The top of the reactor is a cover 2, which supports the stirring paddle 9 and the motor 1. A feeding port and an instrument port are located above the cover for feeding and instrument testing. Flanges are used to connect the reactor to the cover and the pipe, and gaskets are used for sealing. The motor is connected to the stirring paddle via a reducer. Preferably, the stirring paddle is inserted into the reactor to a depth of 2 / 3 for rotational stirring.

[0046] During operation, water flows in through the inlet on the side of the first-stage reactor 3. A water pump can be placed before the inlet to pump the wastewater in. Magnetic adsorbent is added through the feeding hole above the adsorption zone shell of the first-stage reactor 3. The adsorbent adsorbs radioactive nuclides in the wastewater within the first-stage reactor 3. The agitator creates turbulence in the first-stage reactor 3, which acts on the pipe connecting the bottom of the reactor to the second-stage reactor 6. The agitator speed can be calculated using CFD. The speed should be such that iron powder does not settle in the water and clog the pipe, and the agitation speed is greater than the settling speed of the iron powder. Considering factors such as motor efficiency, agitator geometry and structural design, and solution density, a motor power of 1.5 kW is sufficient to prevent settling. Water will enter the second-stage reactor from the pipe at the bottom of the first-stage reactor due to the communicating vessel principle, and undergo a second adsorption reaction in the second-stage reactor.

[0047] Water flows out from the bottom of the secondary reactor and passes through multiple rows of magnetized metal grids in the adsorption zone of the magnetic separation device, eventually flowing into a collection box. The magnetic adsorbent adsorbed on the metal grids moves with the grids to the scraper zone, where it is scraped off and enters another collection box.

[0048] In this embodiment, the removal of 80 mg / L of cobalt ions from water is taken as an example. Figure 13 The rate at which magnetic adsorbent iron powder is added to the primary reactor is 10 g / s, and the rate at which unreacted magnetic adsorbent is added to the secondary reactor is 5 g / s, half that of the primary reactor. Ultimately, the primary reactor adsorbed 53 mg / L of Co. 2+ The removal rate was approximately 66%; the secondary reactor adsorbed 10 mg / L of Co. 2+ The removal rate is approximately 37%; after treatment in a two-stage reactor, the total removal rate of radionuclides is approximately 79%.

[0049] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-tank series rotary chain magnetic separation radioactive wastewater treatment system, characterized in that, A magnetic adsorbent is used to remove radionuclides from wastewater. The device includes a magnetic separation unit (8) and multiple reactors connected in series. The magnetic separation unit (8) includes an adsorption zone (82) and a separation zone (87), wherein: The adsorption zone (82) includes a rotating chain, a plurality of metal grids (83) disposed on the rotating chain, and an adsorption zone shell (84) disposed outside the rotating chain. The rotating chain rotates along the axial direction of the adsorption zone (82). The adsorption zone shell (84) and / or the separation zone shell (88) are provided with permanent magnets. The separation zone (87) is provided with multiple scraper strips (86) along the axial direction. The adsorption zone (82) and the separation zone (87) partially overlap. During the rotation process, the scraper strips contact the metal grid. The permanent magnet magnetizes the metal grid (83), and the metal grid (83) adsorbs the magnetic adsorbent in the wastewater. The rotating chain drives the metal grid (83) to move, and it is scraped off by the scraper at the overlap of the adsorption zone (82) and the separation zone (87). The metal grid (83) includes multiple fan-shaped mesh structures, each fan-shaped structure includes multiple skeletons, each skeleton is arc-shaped, and multiple skeletons are arranged to protrude towards the root of the fan-shaped structure. The permanent magnets are arranged in a Helbeck array.

2. The wastewater treatment system according to claim 1, characterized in that, The diameter of the skeleton is 1~2mm.

3. The wastewater treatment system according to claim 1 or 2, characterized in that, The plurality of metal grids (83) are arranged at equal intervals on the rotating chain.

4. The wastewater treatment system according to claim 1, characterized in that, Multiple scraper blades (86) are arranged in a spiral pattern along the axial direction of the separation zone (87); the pitch of the spirally arranged scraper blades is the same as the distance between two adjacent metal grids.

5. The wastewater treatment system according to claim 1, characterized in that, The reactor is equipped with a stirring paddle (9), which is located at the bottom of the reactor. The stirring paddle (9) includes multiple layers of blades in the radial direction, and the rotation directions of adjacent layers of blades are opposite.

6. The wastewater treatment system according to claim 5, characterized in that, The stirring paddle (9) includes two layers of blades, with forward rotating blades set at 0 to 2 / 3 of the radial direction and reverse rotating blades set at 2 / 3 to 1.

7. The wastewater treatment system according to claim 1, characterized in that, The number of reaction vessels is two.

Images