A radioactive nuclide separation device based on a crown ether extractant

Abstract

The present invention discloses a radioactive nuclide separation device based on a crown ether extractant in the technical field of separation equipment, including an equipment box. A mixing barrel is installed inside the equipment box, and the mixing barrel is used to place a crown ether extractant and a target nuclide substance for mixing. A plurality of groups of fixed seats are fixedly connected to the surface of the fixed frame, and two independent infusion pipes are installed on the plurality of groups of fixed seats. The lower ends of the two infusion pipes both penetrate out of the inside of the equipment box; through the structural setting of the two sealing plates in this solution, the two sealing plates can slide inside the separation box to adjust the positions and relative distances of the two sealing plates, further controlling the formation of upper liquid chambers, lower liquid chambers, and mixed liquid chambers of different sizes inside the separation box, so as to separate the upper liquid and the lower liquid to different degrees, and can be partitioned at different positions along with the stratification positions of the upper liquid and the lower liquid, further increasing the applicability of this device.

Description

Technical Field

[0001] The present invention relates to the technical field of separation equipment, and particularly to a radioactive nuclide separation device based on a crown ether extractant. Background Art

[0002] Crown ether compounds are a class of organic compounds with special structures. Their molecules contain one or more cyclic epoxyethyl units, and the central structure of these epoxyethyl units forms a molecule with a cavity structure. This cavity structure can undergo a specific coordination reaction with metal cations to form stable complexes. This special structural feature endows crown ether compounds with the ability to highly selectively recognize and bind specific metal ions. Crown ether extractants are widely used in the field of radioactive nuclide separation. Their main function is to separate the target nuclide from a complex mixture by undergoing a selective complexation reaction with the nuclide. Since crown ether extractants have different affinities for different metal ions, efficient separation and enrichment of specific nuclides can be achieved.

[0003] After retrieval, Chinese Patent No. CN202322887277.8 discloses an automatic oil-water separation device for recovering nuclides, including a sand core funnel, a pear-shaped separating funnel connected to the lower end of the sand core funnel, a control valve arranged at the lower end of the pear-shaped separating funnel, a filling column connected to the pear-shaped separating funnel through a connecting pipe, and a drain pipe arranged at the lower end of the filling column; filter plates are arranged at both the upper end and the lower end of the filling column, and adsorption fillers are filled between the two filter plates inside the filling column.

[0004] The beneficial effects of the above device are as follows: By combining the sand core funnel and the pear-shaped separating funnel, and combining the filling column filled with adsorption fillers, the three are connected in series to form an overall oil-water separation device. The organic phase in the pear-shaped separating funnel can be recovered, and the inorganic phase enters the filling column for adsorption. After adsorption, the filling column filler can recover the nuclide raw material through pickling. It has a large extraction capacity and excellent continuity, thus effectively solving the problems existing in the prior art.

[0005] In the existing extraction process of radioactive nuclides, first, the extraction liquid and the sample liquid are mixed together, then placed in a separating funnel and left to stand for precipitation, and then the extracted mixed liquid is separated and poured out through the separating funnel. However, after the existing separating funnel pours out the separated liquid, during the operation of the separating funnel, the mixed liquid inside will shake, causing the liquid at the boundary of the mixed liquid to mix, further resulting in a decrease in the dosage of the extracted sample liquid and a low extraction efficiency of radioactive nuclides. For this reason, we propose a radioactive nuclide separation device based on a crown ether extractant. Summary of the Invention

[0006] The object of the present invention is to provide a radioactive nuclide separation device based on crown ether extractants to solve the problems raised in the above background technology.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a radioactive nuclide separation device based on crown ether extractants, comprising an equipment box, a mixing barrel installed inside the equipment box, the mixing barrel being used to place the crown ether extractant and the target nuclide substance for mixing, a plurality of groups of fixing seats fixedly connected to the surface of the fixing frame, two groups of independent infusion tubes being installed on the plurality of groups of the fixing seats, the lower ends of the two groups of infusion tubes both passing through the interior of the equipment box, the other ends of the two groups of infusion tubes both facing the interior of the mixing barrel, the two groups of infusion tubes being used to input the crown ether extractant and the target nuclide substance into the interior of the mixing barrel respectively, the surface of the mixing barrel being fixedly connected to There is a drain pipe, which is connected to the interior of the mixing barrel. A solenoid valve is installed inside the drain pipe. A separation box is also installed inside the equipment box. The separation box is located below the rotation track of the drain pipe. A liquid injection port is provided on the top of the separation box. Two groups of sealing plates are installed inside the separation box. The surface of the sealing plate is provided with a through groove. Two groups of rotating plates are hingedly installed inside the through groove. At the same time, two groups of motors C are fixedly connected to the surface of the sealing plate. The output shafts of the two groups of motors C are respectively connected to the two groups of rotating plates for transmission. The two groups of sealing plates can divide the interior of the separation box into three independent spaces, namely, an upper liquid bin, a lower liquid bin, and a mixed liquid bin.

[0008] Preferably, a fixing frame is fixedly connected to the interior of the equipment box, a mounting seat is fixedly connected to the surface of the fixing frame, a mixing barrel is hingedly installed inside the mounting seat, the fixing frame is arranged in an "L" shape, a motor A is fixedly connected to the upper end surface of the fixing frame, a driving shaft is fixedly connected to the output shaft of the motor A, the lower end of the driving shaft is inserted into the interior of the mixing barrel, a stirring roller is fixedly connected to the surface of the driving shaft, the stirring roller is inserted into the interior of the mixing barrel and is distributed concentrically with the mixing barrel.

[0009] Preferably, the surface of the stirring roller is provided with evenly distributed stirring blades, the stirring blades are arranged in an annular structure and are hollowed out inside, and a filter is installed in the hollowed-out area inside the stirring blades.

[0010] Preferably, the lower end of the driving shaft passes through the mixing barrel and is fixedly connected to a control gear, the surface of the fixing frame is fixedly connected to a mounting plate, the surface of the mounting plate at one end away from the fixing frame is fixedly connected to a fixing shaft, the surface of the fixing shaft is hingedly mounted with a connecting gear, the connecting gear is located on one side of the control gear, the connecting gear and the control gear are meshingly connected, the lower end surface of the mixing barrel is fixedly connected to an inner gear ring, the inner gear ring and the mixing barrel are distributed in concentric circles, and the connecting gear is inserted inside the inner gear ring and meshingly connected to the inner gear ring.

[0011] Preferably, the upper liquid storage bin is located above the upper sealing plate, the lower liquid storage bin is located below the lower sealing plate, and the mixed liquid storage bin is located between the two sealing plates.

[0012] Preferably, the upper turning plate rotates from the side of the upper liquid storage bin to the side of the mixed liquid storage bin, and the lower turning plate rotates from the side of the lower liquid storage bin to the side of the mixed liquid storage bin.

[0013] Preferably, a lead screw is fixedly connected inside the separation box, the lead screw is vertically arranged, a motor B is fixedly connected to the inner wall of the lower end of the separation box, the output shaft of the motor B is in transmission connection with the lead screw, a slider is fixedly connected to the surface of the sealing plate, the slider is adaptively installed on the surface of the lead screw, and the sliding directions of the two sliders are opposite.

[0014] Preferably, a telescopic baffle is fixedly connected to the surface of the sealing plate. The telescopic baffle is provided in three groups, and the three groups of telescopic baffles are respectively located on the upper and lower sides of the two sealing plates and between the two sealing plates.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. Through the structural arrangement of the two sealing plates inside the separation box in this solution, after the extracted mixed liquid enters the separation box, when the extracted mixed liquid stands and precipitates in the separation box, the two sealing plates can partition the interior of the separation box, dividing the interior of the separation box into three independent spaces: the upper liquid storage bin, the lower liquid storage bin, and the mixed liquid storage bin. Among them, the upper layer liquid is isolated in the upper liquid storage bin, the lower layer liquid is isolated in the lower liquid storage bin, and the intersection part of the upper layer liquid and the lower layer liquid is in the mixed liquid storage bin. At this time, when pouring out the upper layer liquid in the upper liquid storage bin or the lower layer liquid in the mixed liquid storage bin, the intersection of the upper layer liquid and the lower layer liquid will not shake and fuse, resulting in the ineffective separation of the upper layer liquid and the lower layer liquid;

[0017] 2. Through the structural arrangement of the two sealing plates in this solution, when the through grooves in the two sealing plates are closed, the upper turning plate rotates from the side of the upper liquid storage bin to the side of the mixed liquid storage bin, and the lower turning plate rotates from the side of the lower liquid storage bin to the side of the mixed liquid storage bin. Further, during the closing process of the turning plates, the upper layer liquid below will be pushed into the mixed liquid storage bin, and the lower layer liquid above will be pushed into the mixed liquid storage bin, further effectively ensuring the purity of the upper layer liquid and the lower layer liquid. Avoiding poor separation effect on the target nuclide substance;

[0018] 3. This solution uses the structural setting of two groups of sealing plates to enable the two groups of sealing plates to slide inside the separation box, adjust the positions and relative spacing of the two groups of sealing plates, and further control the interior of the separation box to form upper liquid bins, lower liquid bins, and mixed liquid bins of different sizes, thereby separating the upper liquid and the lower liquid to different degrees, and being able to perform partitions at different positions according to the stratification positions of the upper liquid and the lower liquid, further increasing the applicability of this device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the internal structure of the equipment box of the present invention;

[0021] Figure 3 This is a schematic diagram of the internal structure of the mixing barrel of the present invention;

[0022] Figure 4 This is a schematic diagram of the internal structure of the separation box of the present invention;

[0023] Figure 5 It is a schematic diagram of the sealing plate structure of the present invention.

[0024] In the figure: 1. Equipment box; 2. Fixed frame; 3. Fixed seat; 4. Infusion tube; 5. Mounting seat; 6. Mixing barrel; 7. Motor A; 8. Driving shaft; 9. Stirring roller; 10. Stirring blade; 11. Filter; 12. Control gear; 13. Mounting plate; 14. Fixed shaft; 15. Connecting gear; 16. Internal gear ring; 17. Drain pipe; 18. Solenoid valve; 19. Separation box; 20. Liquid filling port; 21. Motor B; 22. Screw rod; 23. Sealing plate; 24. Upper liquid tank; 25. Lower liquid tank; 26. Mixing tank; 27. Through slot; 28. Turn plate; 29. ​​Motor C; 30. Sliding block; 31. Telescopic baffle. DETAILED DESCRIPTION

[0025] Example

[0026] See also Figures 1-5 , the present invention provides a technical solution:

[0027] A radioactive nuclide separation device based on a crown ether extractant. Inside the equipment box 1, there is a fixed frame 2 fixedly connected. On the surface of the fixed frame 2, there is a mounting seat 5 fixedly connected. Inside the mounting seat 5, there is a mixing barrel 6 hingedly installed. The mixing barrel 6 is used to place the crown ether extractant and the target nuclide substance for mixing, further enabling the extractant to form a complex or compound with the target nuclide, and realizing the separation and enrichment of the target nuclide during the extraction process. On the surface of the fixed frame 2, there are several groups of fixed seats 3. Two independent infusion tubes 4 are installed on several groups of fixed seats 3. The lower ends of the two infusion tubes 4 both penetrate out of the inside of the equipment box 1. The other ends of the two infusion tubes 4 both face the inside of the mixing barrel 6. The two infusion tubes 4 are respectively used to input the crown ether extractant and the target nuclide substance into the inside of the mixing barrel 6, realizing the automatic feeding for radioactive nuclide separation and increasing the working efficiency of this device.

[0028] The fixed frame 2 is set in an "L" shape. On the upper surface of the fixed frame 2, there is a motor A7 fixedly connected. On the output shaft of the motor A7, there is a drive shaft 8 fixedly connected. The lower end of the drive shaft 8 is inserted into the inside of the mixing barrel 6. On the surface of the drive shaft 8, there is a stirring roller 9 fixedly connected. The stirring roller 9 is inserted into the inside of the mixing barrel 6 and is concentrically distributed with the mixing barrel 6. On the surface of the stirring roller 9, there are evenly distributed stirring blades 10. Further, after the motor A7 is turned on, it drives the drive shaft 8 to connect the stirring roller 9 to rotate inside the mixing barrel 6, further controlling the stirring blades 10 to stir the mixture of the crown ether extractant and the target nuclide substance inside the mixing barrel 6, thereby accelerating the mixing efficiency of the crown ether extractant and the target nuclide substance and enabling the target nuclide to interact with the crown ether extractant to form a complex.

[0029] The stirring blade 10 is set in an annular structure and is hollow inside. Inside the hollow area of the stirring blade 10, there is a filter screen 11 installed. Further, when the stirring blade 10 stirs the mixture of the crown ether extractant and the target nuclide substance inside the mixing barrel 6, it can filter the impurities in the mixture, further increasing the subsequent separation effect of the radioactive nuclide.

[0030] The lower end of the drive shaft 8 penetrates through the mixing barrel 6 and is fixedly connected to a control gear 12. The surface of the fixed frame 2 is fixedly connected to a mounting plate 13. One end surface of the mounting plate 13 away from the fixed frame 2 is fixedly connected to a fixed shaft 14. A connecting gear 15 is hingedly mounted on the surface of the fixed shaft 14. The connecting gear 15 is located on one side of the control gear 12, and the connecting gear 15 and the control gear 12 are meshed and connected. At the same time, the lower end surface of the mixing barrel 6 is fixedly connected to an internal gear ring 16. The internal gear ring 16 and the mixing barrel 6 are concentrically distributed. The connecting gear 15 is inserted into the interior of the internal gear ring 16 and is meshed and connected to the internal gear ring 16. Further, when the motor A7 is turned on and drives the stirring roller 9 to stir, at the same time, the drive shaft 8 is controlled to drive the control gear 12 to mesh with the connecting gear 15 to rotate, and then the internal gear ring 16 is driven by the connecting gear 15 to rotate the mixing barrel 6, controlling the mixing barrel 6 to rotate self in the mounting seat 5, so that the mixing barrel 6 generates centrifugal force during rotation, further controlling the crown ether extractant and the target nuclide substance mixture inside the mixing barrel 6 to be more evenly mixed under the action of centrifugal force, and further increasing the interaction effect between the crown ether extractant and the target nuclide substance. And under the action of the centrifugal force generated by the rotation of the mixing barrel 6, the impurities in the crown ether extractant and the target nuclide substance mixture can be fully captured by the stirring blades 10, thereby improving the filtering effect of the crown ether extractant and the target nuclide substance mixture.

[0031] A drain pipe 17 is fixedly connected to the surface of the mixing barrel 6. The drain pipe 17 is communicated with the interior of the mixing barrel 6. At the same time, a solenoid valve 18 is installed inside the drain pipe 17. When the crown ether extractant and the target nuclide substance interact and mix inside the mixing barrel 6, the drain pipe 17 is closed by the solenoid valve 18 to prevent the mixture inside the mixing barrel 6 from flowing out. When the crown ether extractant and the target nuclide substance mixture inside the mixing barrel 6 have fully interacted, the solenoid valve 18 is opened, so that the extracted mixture inside the mixing barrel 6 is discharged through the drain pipe 17, facilitating the subsequent separation of the radionuclide from the extraction mixture.

[0032] A separation box 19 is also installed inside the equipment box 1. The separation box 19 is located below the rotation trajectory of the drain pipe 17. When the mixing barrel 6 stops rotating, the drain pipe 17 is just above the separation box 19. A liquid injection port 20 is provided on the upper end surface of the separation box 19. Further, the drain pipe 17 can discharge the extracted mixture into the separation box 19 through the liquid injection port 20, facilitating the subsequent static settlement and precipitation of the extracted mixture.

[0033] After the extracted mixture has been statically settled in the separation box 19 for a period of time, the extracted mixture will precipitate and stratify into an upper layer liquid and a lower layer liquid inside the separation box 19. Most of the radionuclides will be in the upper layer liquid or the lower layer liquid, further realizing the separation of the radionuclides.

[0034] Two sets of sealing plates 23 are installed inside the separation box 19, and the inside of the separation box 19 can be blocked and switched through the sealing plates 23. The surface of the sealing plate 23 is provided with a through groove 27, and two sets of rotating plates 28 are hingedly installed inside the through groove 27. At the same time, two sets of motors C29 are fixedly connected to the surface of the sealing plate 23, and the output shafts of the two sets of motors C29 are respectively connected to the two sets of rotating plates 28. After the two sets of motors C29 are turned on, the two sets of rotating plates 28 are driven to rotate in the opposite direction, and the two sets of rotating plates 28 are further controlled to open and close in the through groove 27, so that the through groove 27 can be closed. The two sets of sealing plates 23 can further divide the inside of the separation box 19 into three independent spaces, namely the upper liquid bin 24, the lower liquid bin 25, and the mixed liquid bin 26. The upper liquid bin 24 is located above the upper sealing plate 23, the lower liquid bin 25 is located below the lower sealing plate 23, and the mixed liquid bin 26 is located between the two sets of sealing plates 23. When the mixed liquid after extraction enters the separation box 19, the through slot 27 is controlled to open, so that the mixed liquid after extraction enters the separation box 19, fills the interior of the separation box 19 and settles as it stands. After the mixed liquid after extraction settles and layers, the motor C29 is turned on to run and drive the rotating plate 28 to rotate. The through slot 27 can be further sealed by the rotating plate 28 to achieve phase isolation between the upper liquid bin 24, the lower liquid bin 25, and the mixed liquid bin 26. The upper layer of liquid can be isolated in the upper liquid bin 24, the lower layer of liquid can be isolated in the lower liquid bin 25, and the interface between the upper layer of liquid and the lower layer of liquid is in the mixed liquid bin 26. At this time, when the upper layer of liquid in the upper liquid bin 24 is poured out, the interface between the upper layer of liquid and the lower layer of liquid will not shake and merge, resulting in the inability to effectively separate the upper layer of liquid and the lower layer of liquid.

[0035] In addition, during the closing process of the rotating plate 28, the rotating plate 28 located at the top rotates from the upper liquid bin 24 to the mixed liquid bin 26, and the rotating plate 28 located at the bottom rotates from the lower liquid bin 25 to the mixed liquid bin 26. Furthermore, during the closing process of the rotating plate 28, the upper layer of liquid below is pushed into the mixed liquid bin 26, and the lower layer of liquid above is pushed into the mixed liquid bin 26, thereby further effectively ensuring the purity of the upper layer of liquid and the lower layer of liquid, thereby avoiding poor separation effect on the target nuclide substances.

[0036] Inside the separation box 19, a lead screw 22 is fixedly connected, and the lead screw 22 is vertically arranged. On the lower inner wall of the separation box 19, a motor B21 is fixedly connected, and the output shaft of the motor B21 is in transmission connection with the lead screw 22. On the surface of the sealing plate 23, a slider 30 is fixedly connected, and the slider 30 is adaptively installed on the surface of the lead screw 22. After the motor B21 is turned on, it drives the lead screw 22 to rotate and controls the two sliders 30 to linearly slide on the surface of the lead screw 22, and the sliding directions of the two sliders 30 are opposite. Thus, the positions and relative distances of the two sealing plates 23 inside the separation box 19 are adjusted, and further, different-sized upper liquid chambers 24, lower liquid chambers 25, and mixed liquid chambers 26 are formed inside the separation box 19, so as to separate the upper liquid and the lower liquid to different degrees, and can be partitioned at different positions along with the stratification positions of the upper liquid and the lower liquid, further increasing the applicability of this device.

[0037] On the surface of the sealing plate 23, a telescopic baffle 31 is fixedly connected. The telescopic baffle 31 is arranged in three groups, respectively located on the upper and lower sides of the two sealing plates 23 and between the two sealing plates 23. Further, when the two sealing plates 23 move inside the separation box 19, one side is always kept sealed to prevent the upper liquid chamber 24, the lower liquid chamber 25, and the mixed liquid chamber 26 from communicating with each other, resulting in the mixing of the upper liquid and the lower liquid.

Claims

1. A radionuclide separation device based on a crown ether extractant, comprising an equipment box (1), characterized in that: A mixing barrel (6) is installed inside the equipment box (1), and the mixing barrel (6) is used to place a crown ether extractant and a target nuclide substance for mixing. A plurality of groups of fixing seats (3) are fixedly connected to the surface of the fixing frame (2), and two groups of independent infusion tubes (4) are installed on the plurality of groups of fixing seats (3). The lower ends of the two groups of infusion tubes (4) pass through the interior of the equipment box (1), and the other ends of the two groups of infusion tubes (4) face the interior of the mixing barrel (6). The two groups of infusion tubes (4) are used to respectively input the crown ether extractant and the target nuclide substance into the interior of the mixing barrel (6). A discharge pipe (17) is fixedly connected to the surface of the mixing barrel (6), and the discharge pipe (17) is connected to the interior of the mixing barrel (6). A solenoid valve (18) is installed inside the discharge pipe (17). The equipment box (1) is also provided with a separation box (19) inside. The separation box (19) is located below the rotation track of the liquid discharge pipe (17). A liquid injection port (20) is provided above the separation box (19). Two sets of sealing plates (23) are installed inside the separation box (19). The surface of the sealing plate (23) is provided with a through groove (27). Two sets of rotating plates (28) are hingedly installed inside the through groove (27). Meanwhile, two sets of motors C (29) are fixedly connected to the surface of the sealing plate (23). The output shafts of the two sets of motors C (29) are respectively connected to the two sets of rotating plates (28). The two sets of sealing plates (23) divide the interior of the separation box (19) into three independent spaces, namely, an upper liquid bin (24), a lower liquid bin (25), and a mixed liquid bin (26). The upper liquid bin (24) is located above the upper sealing plate (23), the lower liquid bin (25) is located below the lower sealing plate (23), and the mixed liquid bin (26) is located between the two sets of sealing plates (23); The rotating plate (28) located at the top rotates from the upper liquid bin (24) side to the liquid mixing bin (26) side, and the rotating plate (28) located at the bottom rotates from the lower liquid bin (25) side to the liquid mixing bin (26) side.

2. A radionuclide separation device based on crown ether extractants according to claim 1, characterized in that: A fixing frame (2) is fixedly connected to the interior of the equipment box (1), a mounting seat (5) is fixedly connected to the surface of the fixing frame (2), a mixing barrel (6) is hingedly mounted inside the mounting seat (5), the fixing frame (2) is arranged in an "L" shape, a motor A (7) is fixedly connected to the upper end surface of the fixing frame (2), a drive shaft (8) is fixedly connected to the output shaft of the motor A (7), the lower end of the drive shaft (8) is inserted into the interior of the mixing barrel (6), a stirring roller (9) is fixedly connected to the surface of the drive shaft (8), the stirring roller (9) is inserted into the interior of the mixing barrel (6) and is arranged concentrically with the mixing barrel (6).

3. A radionuclide separation device based on crown ether extractants according to claim 2, characterized in that: The surface of the stirring roller (9) is provided with stirring blades (10) distributed evenly, the stirring blades (10) are arranged in an annular structure and are hollowed out inside, and a filter screen (11) is installed in the hollowed-out area inside the stirring blades (10).

4. A radionuclide separation device based on crown ether extractants according to claim 2, characterized in that: The lower end of the driving shaft (8) passes through the mixing barrel (6) and is fixedly connected to a control gear (12); a mounting plate (13) is fixedly connected to the surface of the fixing frame (2); a fixed shaft (14) is fixedly connected to the surface of the mounting plate (13) at one end away from the fixing frame (2); a connecting gear (15) is hingedly mounted on the surface of the fixing shaft (14); the connecting gear (15) is located on one side of the control gear (12); the connecting gear (15) and the control gear (12) are meshingly connected; an inner gear ring (16) is fixedly connected to the lower end surface of the mixing barrel (6); the inner gear ring (16) and the mixing barrel (6) are arranged in concentric circles; the connecting gear (15) is inserted inside the inner gear ring (16) and is meshingly connected to the inner gear ring (16).

5. The radionuclide separation device based on crown ether extractants according to claim 1, characterized in that: A screw rod (22) is fixedly connected to the interior of the separation box (19), and the screw rod (22) is arranged vertically. A motor B (21) is fixedly connected to the inner wall of the lower end of the separation box (19), and the output shaft of the motor B (21) is transmission-connected to the screw rod (22). A slider (30) is fixedly connected to the surface of the sealing plate (23), and the slider (30) is adaptively mounted on the surface of the screw rod (22), and the sliding directions of the two groups of sliders (30) are opposite.

6. The radionuclide separation device based on crown ether extractants according to claim 1, characterized in that: A telescopic baffle (31) is fixedly connected to the surface of the sealing plate (23), and the telescopic baffle (31) is arranged in three groups. The three groups of telescopic baffles (31) are respectively located at the upper and lower sides of the two groups of sealing plates (23) and between the two groups of sealing plates (23).

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