System for recovering and purifying NMP (N-Methyl Pyrrolidone) by adopting thermal coupling dividing wall column

Abstract

The invention relates to the technical field of NMP recovery, in particular to a system for recovering and purifying NMP by adopting a thermal coupling dividing wall column, which comprises a recovery column, a coarse dehydration column and a dividing wall column which are sequentially communicated backwards, a rectification assembly for further rectifying and purifying NMP is arranged in the dividing wall column, and a rectangular frame is fixedly connected in the recovery column. A gas inlet pipe is fixedly connected to the side wall of the rectangular frame and penetrates through the outer wall of the recovery tower, an NMP concentration sensor is arranged on the gas inlet pipe, a spraying mechanism used for spraying a dissolving solution is arranged at the top end in the rectangular frame, and an upper adjusting mechanism used for adjusting a gas flowing path and a lower adjusting mechanism used for adjusting the gas flowing speed are arranged in the rectangular frame; by arranging the upper adjusting mechanism, the flow path of gas in the rectangular frame can be adjusted according to the concentration of NMP in the gas, so that the retention time of the gas in the rectangular frame can be prolonged when the concentration of the NMP in the gas is increased, the dissolving effect of dissolved water on the NMP is improved, and flexible adjustment can be performed according to actual conditions.

Description

Technical Field

[0001] The invention relates to the technical field of NMP recovery, in particular to a system for recovering and purifying NMP by using a thermally coupled bulkhead tower. Background Art

[0002] NMP is a colorless, transparent, oily liquid with a slight amine odor, low volatility, good thermal stability and chemical stability, can evaporate with water vapor, is hygroscopic, sensitive to light, and is easily soluble in water, ethanol, ether, acetone, ethyl acetate, chloroform and benzene. It can dissolve most organic and inorganic compounds, polar gases, and natural and synthetic polymers. N-methylpyrrolidone is widely used in lithium batteries, medicines, pesticides, pigments, cleaning agents, insulating materials and other industries. After using NMP, it needs to be distilled and recovered to save it.

[0003] The prior art discloses a three-tower vacuum distillation system and process for recovering and purifying NMP with publication number CN118526805A. The system forms a complete NMP purification system by adopting a special mechanical structure of "three-tower vacuum distillation" combined with waste gas treatment, thereby improving the efficiency and quality of purification. In addition, the system provides a multi-layer circulation mechanism and a jet mechanism, thereby enabling the gas to be recovered multiple times. Meanwhile, a flow divider is used to control the flow of a dissolved liquid in each layer of the circulation mechanism, and the concentration of the dissolved liquid is controlled according to different layers, thereby achieving efficient utilization of the dissolved liquid and improving the recovery efficiency.

[0004] Although the gas recovery effect can be improved, there are still some problems in the actual recovery process. Since the recovery system is processed by multiple recovery methods, the residence time of the gas in the recovery process cannot be changed, and thus the concentration of NMP in the gas cannot be adjusted accordingly. Moreover, when recovering dilute NMP in the gas, it not only increases the equipment operating cost, but also greatly reduces the recovery efficiency of the device.

[0005] Therefore, a system for recovering and purifying NMP by using a thermally coupled dividing wall tower is proposed to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to solve the shortcomings of the background technology and propose a system for recovering and purifying NMP using a thermally coupled bulkhead tower.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is: a system for recovering and purifying NMP using a thermally coupled bulkhead tower, comprising a recovery tower, a rough dehydration tower and a bulkhead tower which are sequentially connected to each other backwards, wherein a distillation assembly for further distilling and purifying NMP is provided in the bulkhead tower, a rectangular frame is fixedly connected inside the recovery tower, an air inlet pipe is fixedly connected to the side wall of the rectangular frame, and the air inlet pipe runs through the outer wall of the recovery tower, an NMP concentration sensor is provided on the air inlet pipe, a spraying mechanism for spraying a dissolving liquid is provided at the top of the rectangular frame, and an upper regulating mechanism for regulating a gas flow route and a lower regulating mechanism for regulating a gas flow rate are respectively provided in the rectangular frame; The cam is provided with a pair of upper and lower adjusting rods, the upper and lower adjusting rods are arranged on the inner side of the rectangular frame, and the lower and lower adjusting rods are arranged between the upper and lower adjusting rods. A pair of winding rollers are rotatably connected to the inner side of the recovery tower, and the side walls of the lower adjusting rods are fixedly connected to a pair of upper pull ropes, and the other ends of the upper pull ropes pass through the outer wall of the rectangular frame and are fixedly connected to the outer wall of the winding roller. The side walls of the upper adjusting rods are fixedly connected to a pair of lower pull ropes, and the other ends of the lower pull ropes pass through the outer wall of the rectangular frame and are fixedly connected to the winding roller. The inner side of the rectangular frame is rotatably connected to a pair of guide rollers, and the lower pull ropes pass through the outer walls of the guide rollers and are arranged in a U-shape in the rectangular frame. The upper and lower adjusting rods are fixedly connected to a shielding cloth away from the side, and the outer wall of the rectangular frame is provided with a reset mechanism for pulling the shielding cloth to reset, and an air outlet is opened on the side wall of the rectangular frame and away from the air inlet pipe.

[0008] In the above technical solution, further, a winding motor is fixedly connected to the outer wall of the recovery tower and the position corresponding to the winding roller, the output end of the winding motor passes through the inner wall of the recovery tower and is fixedly connected to the side wall of the winding roller, and the winding motor is electrically connected to the NMP concentration sensor through a controller.

[0009] In the above technical solution, further, the reset mechanism includes a spiral spring, a pair of support plates are fixedly connected to the outer wall of the rectangular frame and at positions corresponding to the shielding cloth, a rotating cylinder is rotatably connected between the support plates, the other end of the shielding cloth passes through the outer wall of the rectangular frame and is wrapped and fixedly connected to the rotating cylinder, three spiral springs are provided, and the three spiral springs are all provided on the inner side of the rotating cylinder, one end of the spiral spring is fixedly connected to the side wall of the support plate, and the other end of the spiral spring is fixedly connected to the inner wall of the rotating cylinder.

[0010] In the above technical solution, further, a right-angle plate with an inclined surface is fixedly connected to the bottom of the rectangular frame, and the lowest end of the inclined surface of the right-angle plate is arranged on a side close to the air outlet.

[0011] In the above technical solution, further, a right-angle block with an inclined surface for guiding flow is fixedly connected to the inner side of the rectangular frame and located next to the air intake pipe.

[0012] In the above technical solution, further, the lower adjustment mechanism includes an adjustment block, a pair of which is provided, the adjustment block is fixedly connected to the middle of the inner side of the rectangular frame, and the side of the adjustment block away from it is flush with the side close to the upper adjustment rod, the side close to the adjustment block is provided with a semi-heart-shaped guide groove, and the guide grooves are arranged in opposite directions, the inner sides of the guide grooves are provided with water drop-shaped flow partition blocks, the flow partition blocks are fixedly connected to the inner side of the rectangular frame, the flow partition blocks and the guide grooves are combined to form a passage for gas to pass through, the adjustment block is provided with a blocking mechanism for blocking the passage, and the NMP concentration sensor is electrically connected to the blocking mechanism through a controller.

[0013] In the above technical scheme, further, the blocking mechanism includes an adjusting motor, a top frame is fixedly connected to the top of the rectangular frame, a disc is rotatably connected to the top of the rectangular frame, the adjusting motor is fixedly connected to the top of the top frame, the output end of the adjusting motor passes through the top of the top frame and is fixedly connected to the top of the disc, a pair of protruding blocks are fixedly connected to the outer wall of the disc, and the outer wall of the protruding block is set to an arc surface, a receiving groove is opened through the top of the adjusting block, a blocking plate is slidably connected to the inner side of the storing groove, a round rod is fixedly connected to the top of the blocking plate, and the top of the round rod passes through the top of the rectangular frame, a sliding groove is opened at the top of the rectangular frame and at a position corresponding to the round rod, and the round rod is in contact with the outer wall of the disc.

[0014] In the above technical solution, further, a corrugated cover is fixedly connected between the inner side of the slide groove and the outer wall of the round rod, and a plurality of upper springs are fixedly connected between the inner side of the storage groove and the side wall of the blocking plate.

[0015] In the above technical solution, further, a plurality of drainage grooves are equidistantly provided at the bottom of the regulating block and the bottom of the flow isolation block.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention can adjust the flow path of the gas in the rectangular frame according to the concentration of NMP in the gas by setting the upper regulating mechanism, so that the residence time of the gas in the rectangular frame can be increased when the concentration of NMP in the gas increases, thereby improving the dissolution effect of dissolved water on NMP, and can be flexibly adjusted according to actual conditions.

[0017] 2. The present invention can open when the NMP concentration in the gas is deeper through the setting of the lower regulating mechanism, thereby having a flow-blocking effect on the flow rate of the gas in the rectangular frame, and cooperating with the upper regulating mechanism to further increase the residence time of the gas in the rectangular frame, and further improve the dissolution effect of dissolved water on NMP. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The overall structure schematic diagram of the NMP recovery and purification system of the present invention; Figure 2 It is a schematic diagram of the rear perspective structure of the recovery tower of the present invention; Figure 3 It is a schematic diagram of a partially cutaway three-dimensional structure of the front side of the recovery tower of the present invention; Figure 4 It is a schematic diagram of the full-cut three-dimensional structure of the rectangular frame of the present invention; Figure 5 It is a schematic diagram of the three-dimensional structure of the rectangular frame side of the present invention; Figure 6 It is a schematic diagram of a three-dimensional structure of a rectangular frame in a top view and in full section according to the present invention; Figure 7 It is a schematic diagram of the overall appearance structure of the rotating drum and the shielding cloth of the present invention; Figure 8 It is a schematic diagram of the three-dimensional structure of the regulating block, the flow isolation block and the disc separation of the present invention; Fig. 9 It is a schematic diagram of the flow direction of the guide channel of the present invention.

[0019] In the figure: 1. recovery tower; 2. rough dehydration tower; 3. bulkhead tower; 4. distillation assembly; 5. rectangular frame; 6. air inlet pipe; 7. NMP concentration sensor; 8. spraying mechanism; 9. upper adjustment rod; 10. lower adjustment rod; 11. winding roller; 12. upper pull rope; 13. guide roller; 14. lower pull rope; 15. shielding cloth; 16. winding motor; 17. scroll spring; 18. support plate; 19. rotating cylinder; 20. air outlet; 21. right angle plate; 22. right angle block; 23. adjustment block; 24. guide groove; 25. flow partition block; 26. adjustment motor; 27. top frame; 28. disc; 29. ​​protruding block; 30. storage groove; 31. blocking plate; 32. round rod; 33. corrugated cover; 34. upper spring; 35. drainage groove. DETAILED DESCRIPTION

[0020] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] like Figure 1-9A system for recovering and purifying NMP using a thermally coupled bulkhead tower is shown, comprising a recovery tower 1, a rough dehydration tower 2 and a bulkhead tower 3 which are sequentially connected to each other backwards, a bottom material extraction pipeline of the recovery tower 1 is connected to the rough dehydration tower 2 and the bulkhead tower 3, and a monitoring component and a secondary dissolution mechanism are provided at the top of the recovery tower 1 to prevent the discharge of gas containing NMP, a distillation component 4 for further distillation and purification of NMP is provided in the bulkhead tower 3, and the distillation component 4 includes a middle distillation section, a common distillation section (located below the middle distillation section) and a common distillation section (located above the middle distillation section), a rectangular frame 5 is fixedly connected inside the recovery tower 1, an air inlet pipe 6 is fixedly connected to the side wall of the rectangular frame 5, and the air inlet pipe 6 runs through the outer wall of the recovery tower 1, an NMP concentration sensor 7 is provided on the air inlet pipe 6, a spraying mechanism 8 for spraying a dissolving liquid is provided at the top of the rectangular frame 5, and an upper regulating mechanism for regulating the gas flow route and a lower regulating mechanism for regulating the gas flow rate are respectively provided in the rectangular frame 5; Before use, the medium and high concentration alarm values ​​of the NMP concentration sensor 7 are set first. Then, when dissolving the NMP in the gas, the spraying mechanism 8 is first controlled to start spraying the dissolved water in the rectangular frame 5, and then the valve is opened to discharge the gas with NMP into the rectangular frame 5, and the gas is combined with the sprayed water droplets, and discharged from the gas outlet 20 due to gravity, and falls into the bottom of the recovery tower 1. When the dissolved liquid at the bottom of the recovery tower 1 reaches the set concentration, that is, 80%-90% (the optimal NMP dissolved liquid output concentration is 85), the dissolved liquid at the bottom of the recovery tower 1 can be input into the rough dehydration tower 2 for subsequent processing; After the NMP gas is recovered and processed by the recovery tower 1, it is discharged into the rough dehydration tower 2 through a pipeline. The treated water-containing NMP first enters the rough dehydration tower 2 for dehydration. Under negative pressure operation conditions, by controlling the tower top reflux ratio and the reflux temperature, a large amount of water is extracted from the tower top, and a crude NMP product (1%) with a low water content is extracted from the tower bottom, and enters the bulkhead tower 3, and enters the middle of the pre-separation section of the middle distillation section in the distillation component 4. The tower top extracts low-boiling substances (mainly water or water-containing NMP) and can be returned to the rough dehydration tower 2 for mixing, and the high-boiling substances (PVDF) are extracted from the tower bottom, and the high-purity NMP is extracted from the main separation section of the middle distillation section for discharge.

[0023] The upper adjustment mechanism includes an upper adjustment rod 9 and a lower adjustment rod 10. A pair of upper adjustment rods 9 are provided. The upper adjustment rods 9 are arranged inside the rectangular frame 5. The lower adjustment rods 10 are arranged between the upper adjustment rods 9. A pair of winding rollers 11 are rotatably connected to the inside of the recovery tower 1. A pair of upper pull ropes 12 are fixedly connected to the side wall of the lower adjustment rod 10, and the other end of the upper pull rope 12 passes through the outer wall of the rectangular frame 5 and is fixedly connected to the outer wall of the winding roller 11. A pair of lower pull ropes 14 are fixedly connected to the side walls of the upper adjustment rods 9, and the other end of the lower pull ropes 14 passes through the outer wall of the rectangular frame 5 and is wound around A pair of guide rollers 13 are rotatably connected to the inner side of the rectangular frame 5, which guide the sliding direction of the lower pull rope 14 and improve the smoothness of the lower pull rope 14 during pulling. The lower pull rope 14 passes through the outer wall of the guide roller 13 and is arranged in the rectangular frame 5 in a U-shape. The upper adjustment rod 9 and the lower adjustment rod 10 are fixedly connected to the shielding cloth 15 on the away side. The outer wall of the rectangular frame 5 is provided with a reset mechanism for pulling the shielding cloth 15 to reset. The side wall of the rectangular frame 5 and the side away from the air inlet pipe 6 are provided with an air outlet 20; The outer wall of the recovery tower 1 and the position corresponding to the winding roller 11 are fixedly connected with a winding motor 16, the output end of the winding motor 16 passes through the inner wall of the recovery tower 1 and is fixedly connected to the side wall of the winding roller 11, and the winding motor 16 is electrically connected to the NMP concentration sensor 7 through the controller; The reset mechanism includes a spiral spring 17, a pair of support plates 18 are fixedly connected to the outer wall of the rectangular frame 5 and at positions corresponding to the shielding cloth 15, a rotating cylinder 19 is rotatably connected between the support plates 18, the other end of the shielding cloth 15 passes through the outer wall of the rectangular frame 5 and is wound and fixedly connected to the rotating cylinder 19, three spiral springs 17 are provided, and the three spiral springs 17 are all arranged on the inner side of the rotating cylinder 19, one end of the spiral spring 17 is fixedly connected to the side wall of the support plate 18, and the other end of the spiral spring 17 is fixedly connected to the inner wall of the rotating cylinder 19; When the NMP concentration sensor 7 detects a medium concentration, the winding motor 16 is controlled to start and drive the winding roller 11 to rotate, thereby winding the upper pull rope 12 and the lower pull rope 14 and winding them around the winding roller 11. At the same time, through the winding of the upper pull rope 12 and the lower pull rope 14, the upper adjustment rod 9 and the lower adjustment rod 10 are driven to slide on the inner side of the rectangular frame 5 under the guidance of the guide roller 13, and the shielding cloth 15 is pulled to move, so that the shielding cloth 15 is pulled out of the wound part on the rotating drum 19. At the same time, since the other end of the shielding cloth 15 is fixed on the rotating drum 19, the rotating drum 19 will be driven to rotate simultaneously during the process of pulling the shielding cloth 15, and since one end of the volute spring 17 is fixed to the inner wall of the rotating drum 19 and the other end is fixed to the side wall of the support plate 18; Therefore, the rotation of the rotating cylinder 19 will gradually compress the volute spring 17, and then the upper adjusting rod 9 will be pulled to the side of the guide roller 13, and at the same time the lower adjusting rod 10 will be pulled to the specified position (at this time, there is a certain distance between the lower adjusting rod 10 and the inner wall of the rectangular frame 5, which is the same as the distance between the upper adjusting rod 9 and the inner wall of the rectangular frame 5), so that the shielding cloth 15 is completely opened, and an S-shaped corridor is formed in the rectangular frame 5 through the shielding cloth 15, which will block the gas discharged from the air inlet pipe 6, so that when the NMP concentration in the gas increases, the residence time of the gas in the rectangular frame 5 can be increased, thereby improving the dissolution effect of dissolved water on NMP, which can be flexibly adjusted according to actual conditions, and finally, when retracting, the winding motor 16 is controlled to start in reverse and repeat the above operation in reverse.

[0024] In order to facilitate the sprayed dissolved water to be quickly discharged from the air outlet 20, a right-angle plate 21 with an inclined surface is fixedly connected to the bottom of the rectangular frame 5, and the lowest end of the inclined surface of the right-angle plate 21 is arranged on the side close to the air outlet 20. The arrangement of the right-angle plate 21 facilitates the diversion of the dissolved water in the rectangular frame 5, and then quickly discharges the dissolved water from the inside of the rectangular frame 5 to avoid accumulation in the rectangular frame 5. A right-angle block 22 with an inclined surface for diversion is fixedly connected to the inner side of the rectangular frame 5 and is located next to the air inlet pipe 6. The arrangement of the right-angle block 22 can divert the gas discharged from the air inlet pipe 6 to avoid direct blowing to the air outlet 20, thereby further improving the recovery effect of the device. A number of drainage grooves 35 are equidistantly provided at the bottom of the regulating block 23 and the bottom of the flow isolation block 25. The arrangement of the drainage grooves 35 can prevent the dissolved water in the rectangular frame 5 from being blocked by the regulating block 23, thereby further facilitating the discharge of the dissolved water.

[0025] In order to have a flow-blocking effect on the flow rate of the gas in the rectangular frame 5, the lower regulating mechanism includes an regulating block 23, a pair of regulating blocks 23 are provided, the regulating blocks 23 are fixedly connected to the middle of the inner side of the rectangular frame 5, and the side of the regulating block 23 away from each other is flush with the side close to the upper regulating rod 9, a semi-heart-shaped guide groove 24 is provided on the side close to the regulating block 23, and the directions of the guide grooves 24 are arranged in opposite directions, and a water drop-shaped flow block 25 is provided on the inner side of the guide groove 24, and the flow block 25 is fixedly connected to the inner side of the rectangular frame 5, and the flow block 25 and the guide groove 24 are combined to form a passage for the gas to pass through, and a blocking mechanism for blocking the passage is provided on the regulating block 23, and the NMP concentration sensor 7 is electrically connected to the blocking mechanism through the controller; The blocking mechanism includes an adjusting motor 26, a top frame 27 is fixedly connected to the top of the rectangular frame 5, a disc 28 is rotatably connected to the top of the rectangular frame 5, the adjusting motor 26 is fixedly connected to the top of the top frame 27, the output end of the adjusting motor 26 passes through the top of the top frame 27 and is fixedly connected to the top of the disc 28, a pair of protruding blocks 29 are fixedly connected to the outer wall of the disc 28, and the outer wall of the protruding block 29 is set as an arc surface, the top of the adjusting block 23 is penetrated by a receiving groove 30, the inner side of the receiving groove 30 is slidably connected to a blocking plate 31, the top of the blocking plate 31 is fixedly connected to a round rod 32, and the top of the round rod 32 passes through the top of the rectangular frame 5, a sliding groove is set at the top of the rectangular frame 5 and at a position corresponding to the round rod 32, and the round rod 32 contacts the outer wall of the disc 28; When the NMP concentration sensor 7 detects a high concentration, the regulating motor 26 will be controlled to start driving the disc 28 to rotate, thereby driving the protruding block 29 to rotate and squeeze the round rod 32 to move, thereby pushing the blocking plate 31 to slide on the inner side of the receiving groove 30, and gradually compressing the upper spring 34, thereby opening the channel, so that the gas guided by the upper regulating mechanism can pass through the channel. At this time, a part of the gas will enter the channel, and the other part of the gas will pass by the original flow block 25, and the gas coming out of the channel will flow back and collide head-on with the gas passing by the flow block 25. The force after the collision plays a role in reducing the gas flow rate. After two collisions, the gas flow rate will be greatly weakened, thereby playing a blocking effect on the gas flow rate in the rectangular frame 5, further increasing the residence time of the gas in the rectangular frame 5, and further improving the dissolution effect of dissolved water on NMP.

[0026] In order to prevent the gas in the rectangular frame 5 from being discharged into the top frame 27, a corrugated cover 33 is fixedly connected between the inner side of the slide groove and the outer wall of the round rod 32. The setting of the corrugated cover 33 will not only not hinder the normal sliding of the round rod 32, but also block the slide groove to prevent the gas in the rectangular frame 5 from being discharged into the top frame 27. A plurality of upper springs 34 are fixedly connected between the inner side of the storage groove 30 and the side wall of the blocking plate 31. The setting of the upper spring 34 makes it easy to adjust the motor 26 to drive the disc 28 to reverse and release the squeezing of the round rod 32. Under the elastic force of the upper spring 34, the round rod 32 and the blocking plate 31 are quickly pushed to reset, thereby maintaining the blocking of the passage.

[0027] The basic principles, main features and advantages of the present invention are shown and described above.

[0028] Those skilled in the art should understand that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments and the specification only describe the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. These changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A system for recovering and purifying NMP using a thermally coupled bulkhead tower, characterized in that: The invention comprises a recovery tower (1), a rough dehydration tower (2) and a bulkhead tower (3) which are arranged in sequence and connected to each other backwards, wherein the bulkhead tower (3) is provided with a distillation assembly (4) for further distilling and purifying NMP, the recovery tower (1) is fixedly connected with a rectangular frame (5), the side wall of the rectangular frame (5) is fixedly connected with an air inlet pipe (6), and the air inlet pipe (6) is arranged to penetrate the outer wall of the recovery tower (1), an NMP concentration sensor (7) is arranged on the air inlet pipe (6), the top end of the rectangular frame (5) is provided with a spraying mechanism (8) for spraying a dissolving liquid, and the rectangular frame (5) is provided with an upper regulating mechanism for regulating a gas flow route and a lower regulating mechanism for regulating a gas flow rate; The upper adjustment mechanism comprises an upper adjustment rod (9) and a lower adjustment rod (10), wherein a pair of upper adjustment rods (9) are provided, wherein the upper adjustment rod (9) is provided inside the rectangular frame (5), and the lower adjustment rod (10) is provided between the upper adjustment rods (9). A pair of winding rollers (11) are rotatably connected to the inside of the recovery tower (1), and a pair of upper pull ropes (12) are fixedly connected to the side walls of the lower adjustment rods (10), and the other ends of the upper pull ropes (12) pass through the outer wall of the rectangular frame (5) and are wound and fixedly connected to the outer wall of the winding roller (11). The side walls of the upper adjustment rods (9) are fixedly connected to the pair of lower pull ropes (11). 4), and the other ends of the pull-down ropes (14) pass through the outer wall of the rectangular frame (5) and are wound and fixedly connected to the winding roller (11); a pair of guide rollers (13) are rotatably connected to the inner side of the rectangular frame (5); the pull-down ropes (14) pass through the outer wall of the guide roller (13) and are arranged in a U-shape in the rectangular frame (5); the upper adjustment rod (9) and the lower adjustment rod (10) are fixedly connected to the shielding cloth (15) on the away side; the outer wall of the rectangular frame (5) is provided with a reset mechanism for pulling the shielding cloth (15) to reset; and an air outlet (20) is provided on the side wall of the rectangular frame (5) and away from the air inlet pipe (6).

2. A system for recovering and purifying NMP using a thermally coupled bulkhead tower according to claim 1, characterized in that: A winding motor (16) is fixedly connected to the outer wall of the recovery tower (1) and at a position corresponding to the winding roller (11); an output end of the winding motor (16) passes through the inner wall of the recovery tower (1) and is fixedly connected to the side wall of the winding roller (11); and the winding motor (16) is electrically connected to the NMP concentration sensor (7) via a controller.

3. A system for recovering and purifying NMP using a thermally coupled bulkhead tower according to claim 1, characterized in that: The reset mechanism comprises a scroll spring (17); a pair of support plates (18) are fixedly connected to the outer wall of the rectangular frame (5) and at positions corresponding to the shielding cloth (15); a rotating cylinder (19) is rotatably connected between the support plates (18); the other end of the shielding cloth (15) passes through the outer wall of the rectangular frame (5) and is wound and fixedly connected to the rotating cylinder (19); three scroll springs (17) are provided, and the three scroll springs (17) are all provided on the inner side of the rotating cylinder (19); one end of the scroll spring (17) is fixedly connected to the side wall of the support plate (18), and the other end of the scroll spring (17) is fixedly connected to the inner wall of the rotating cylinder (19).

4. A system for recovering and purifying NMP using a thermally coupled bulkhead tower according to claim 1, characterized in that: A right-angle plate (21) having an inclined surface is fixedly connected to the inner bottom of the rectangular frame (5), and the lowest end of the inclined surface of the right-angle plate (21) is arranged on a side close to the air outlet (20).

5. A system for recovering and purifying NMP using a thermally coupled bulkhead tower according to claim 1, characterized in that: A right-angle block (22) having an inclined surface for guiding flow is fixedly connected to the inner side of the rectangular frame (5) and located next to the air intake pipe (6).

6. A system for recovering and purifying NMP using a thermally coupled bulkhead tower according to claim 1, characterized in that: The lower adjustment mechanism comprises an adjustment block (23), a pair of the adjustment blocks (23) are provided, the adjustment blocks (23) are fixedly connected to the middle part of the inner side of the rectangular frame (5), and the side of the adjustment block (23) away from each other is flush with the side of the upper adjustment rod (9) close to each other, a semi-heart-shaped guide groove (24) is provided on the side of the adjustment block (23) close to each other, and the guide grooves (24) are arranged in opposite directions, a water drop-shaped flow block (25) is provided on the inner side of each of the guide grooves (24), the flow block (25) is fixedly connected to the inner side of the rectangular frame (5), the flow block (25) and the guide groove (24) are combined to form a passage for gas to pass through, a blocking mechanism for blocking the passage is provided on the adjustment block (23), and the NMP concentration sensor (7) is electrically connected to the blocking mechanism via a controller.

7. A system for recovering and purifying NMP using a thermally coupled bulkhead tower according to claim 6, characterized in that: The blocking mechanism comprises an adjusting motor (26), a top frame (27) is fixedly connected to the top of the rectangular frame (5), a disc (28) is rotatably connected to the top of the rectangular frame (5), the adjusting motor (26) is fixedly connected to the top of the top frame (27), the output end of the adjusting motor (26) passes through the top of the top frame (27) and is fixedly connected to the top of the disc (28), a pair of protruding blocks (29) are fixedly connected to the outer wall of the disc (28), and the outer wall of the protruding block (29) is arranged as an arc surface, the top of each adjusting block (23) is provided with a receiving groove (30) through the top, a blocking plate (31) is slidably connected to the inner side of the receiving groove (30), a round rod (32) is fixedly connected to the top of the blocking plate (31), and the top of the round rod (32) passes through the top of the rectangular frame (5), a sliding groove is provided at the top of the rectangular frame (5) and at a position corresponding to the round rod (32), and the round rod (32) contacts the outer wall of the disc (28).

8. A system for recovering and purifying NMP using a thermally coupled bulkhead tower according to claim 7, characterized in that: A corrugated cover (33) is fixedly connected between the inner side of the slide groove and the outer wall of the round rod (32), and a plurality of upper springs (34) are fixedly connected between the inner side of the storage groove (30) and the side wall of the blocking plate (31).

9. A system for recovering and purifying NMP using a thermally coupled bulkhead tower according to claim 6, characterized in that: A plurality of drainage grooves (35) are equidistantly provided at the bottom of the regulating block (23) and the bottom of the flow isolation block (25).

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