A system for recycling and purifying NMP by using thermally coupled dividing wall column

Abstract

The application relates to the technical field of NMP recovery, in particular to a system for recovering and purifying NMP by using a heat-coupled dividing wall column, which comprises a recovery tower, a crude dehydration tower and a dividing wall column which are sequentially and backwardly communicated, a rectifying assembly for further rectifying and purifying NMP is arranged in the dividing wall column, a rectangular frame is fixedly connected in the recovery tower, 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 for spraying a dissolving solution is arranged at the top of the rectangular frame, an upper adjusting mechanism for adjusting the flow route of the gas and a lower adjusting mechanism for adjusting the flow speed of the gas are arranged in the rectangular frame, the upper adjusting mechanism can adjust the flow path of the gas in the rectangular frame according to the concentration of NMP in the gas, the residence time of the gas in the rectangular frame can be increased when the concentration of NMP in the gas is deepened, the dissolving effect of the water on the NMP can be improved, and the system can be flexibly adjusted according to the actual situation.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of NMP recovery, and in particular to a system for recovering and purifying NMP by adopting thermal coupling compartment walls. BACKGROUND

[0002] NMP is a colorless transparent oily liquid with a slight amine odor, low volatility, good thermal stability and chemical stability, can volatilize with water vapor, has hygroscopicity, is sensitive to light, is easily soluble in water, ethanol, diethyl ether, acetone, ethyl acetate, chloroform and benzene, can dissolve most organic and inorganic compounds, polar gases, natural and synthetic polymer compounds, and is widely used in lithium batteries, medicines, pesticides, pigments, cleaning agents, insulating materials and other industries. After NMP is used, it needs to be recovered and treated by rectification to save resources.

[0003] The system and process for recovering and purifying NMP by adopting three-tower vacuum rectification disclosed in the prior art CN118526805A form a complete NMP purification system by adopting the special mechanical structure of “three-tower vacuum rectification” combined with waste gas treatment, improve the efficiency and quality of purification, and through the setting of the multi-layer circulating mechanism and the air injection mechanism, the gas can be recycled multiple times, and the concentration of the dissolved liquid in each layer of the circulating mechanism is controlled according to different layers to realize efficient use of the dissolved liquid and improve the recovery efficiency.

[0004] Although the recovery effect of the gas can be improved, there are still some problems in the actual recovery process. Since the recovery system is processed by multiple recycling, the residence time of the gas in the recovery process cannot be changed, and accordingly, the corresponding adjustment cannot be made according to the concentration of NMP in the gas, and when the dilute NMP in the gas is recovered, not only the equipment operation cost is increased, but also the recovery efficiency of the device is greatly reduced.

[0005] Therefore, a system for recovering and purifying NMP by adopting thermal coupling compartment walls is proposed to solve the above problems. SUMMARY

[0006] The purpose of the application is to solve the problems in the background art and provide a system for recovering and purifying NMP by adopting thermal coupling compartment walls.

[0007] To achieve the above object, the technical scheme adopted by the present application is: a system for recycling and purifying NMP by using heat-coupled dividing wall column, comprising a recycling tower, a crude dehydration tower and a dividing wall column which are sequentially and backwardly connected, a rectifying assembly for further rectifying and purifying NMP is arranged in the dividing wall column, a rectangular frame is fixedly connected inside the recycling tower, an air inlet pipe is fixedly connected to the side wall of the rectangular frame and penetrates through the outer wall of the recycling tower, an NMP concentration sensor is arranged on the air inlet pipe, a spraying mechanism for spraying dissolving liquid is arranged at the top end inside the rectangular frame, an upper adjusting mechanism for adjusting the gas flow route and a lower adjusting mechanism for adjusting the gas flow rate are respectively arranged inside the rectangular frame.

[0008] The upper adjusting mechanism comprises upper adjusting rods and lower adjusting rods, one pair of upper adjusting rods are arranged, the upper adjusting rods are arranged inside the rectangular frame, the lower adjusting rods are arranged between the upper adjusting rods, a pair of winding rollers are rotatably connected to the inner side of the recycling tower, a pair of upper pull ropes are fixedly connected to the side wall of the lower adjusting rods, and the other ends of the upper pull ropes are fixedly connected to the outer wall of the winding rollers by winding through the outer wall of the rectangular frame, a pair of lower pull ropes are fixedly connected to the side wall of each of the upper adjusting rods, and the other ends of the lower pull ropes are fixedly connected to the winding rollers by winding through the outer wall of the rectangular frame, a pair of guide rollers are rotatably connected to the inner side of the rectangular frame, the lower pull ropes are arranged in a U-shaped manner inside the rectangular frame by penetrating through the outer wall of the guide rollers, the upper adjusting rods and the lower adjusting rods are fixedly connected to shielding cloths away from one side, the outer wall of the rectangular frame is provided with a reset mechanism for pulling the shielding cloths back to the original position, and an air outlet is formed in the side wall of the rectangular frame away from the air inlet pipe.

[0009] In the above technical scheme, further, winding motors are fixedly connected to the outer wall of the recycling tower at positions corresponding to the winding rollers, the output ends of the winding motors are fixedly connected to the side wall of the winding rollers by penetrating through the inner wall of the recycling tower, and the winding motors are electrically connected to the NMP concentration sensor through the controller.

[0010] In the above technical scheme, further, the reset mechanism comprises spiral springs, a pair of support plates are fixedly connected to the outer wall of the rectangular frame at positions corresponding to the shielding cloths, a rotating cylinder is rotatably connected between the support plates, the other ends of the shielding cloths are fixedly connected to the rotating cylinder by winding through the outer wall of the rectangular frame, three spiral springs are arranged, and the three spiral springs are arranged inside the rotating cylinder, one end of each of the spiral springs is fixedly connected to the side wall of the support plate, and the other end of each of the spiral springs is fixedly connected to the inner wall of the rotating cylinder.

[0011] In the above technical scheme, 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 the side close to the air outlet.

[0012] In the above technical solution, further, the rectangular frame inside and beside the air inlet pipe is fixedly connected with a right-angle block with an inclined surface for flow guiding.

[0013] In the above technical solution, further, the lower adjusting mechanism comprises adjusting blocks, a pair of the adjusting blocks are arranged, the adjusting blocks are fixedly connected to the middle part of the inner side of the rectangular frame, and the side away from the adjusting blocks is flush with the side close to the upper adjusting rod, the side close to the adjusting blocks is provided with semicircular flow guiding grooves, the directions of the flow guiding grooves are opposite, water drop-shaped flow blocking blocks are arranged in the inner sides of the flow guiding grooves, the flow blocking blocks are fixedly connected to the inner side of the rectangular frame, the flow guiding grooves and the flow blocking blocks are combined to form a gas passing channel, the adjusting blocks are provided with a plugging mechanism for plugging the channel, and the NMP concentration sensor is electrically connected to the plugging mechanism through the controller.

[0014] In the above technical solution, further, the plugging mechanism comprises 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 is fixedly connected to the top end of the disc through the top of the top frame, a pair of convex blocks are fixedly connected to the outer wall of the disc, the outer wall of the convex blocks is provided with an arc surface, a receiving groove is formed in the top of the adjusting block, a plugging plate is slidably connected to the inner side of the receiving groove, a circular rod is fixedly connected to the top of the plugging plate, the top end of the circular rod is arranged through the top of the rectangular frame, a sliding groove is formed in the top of the rectangular frame and corresponds to the circular rod, and the circular rod is in contact with the outer wall of the disc.

[0015] In the above technical solution, further, a corrugated cover is fixedly connected between the inner side of the sliding groove and the outer wall of the circular rod, and a plurality of upper springs are fixedly connected between the inner side of the receiving groove and the side wall of the plugging plate.

[0016] In the above technical solution, further, a plurality of drainage grooves are equidistantly formed in the bottom of the adjusting block and the bottom of the flow blocking block.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] 1. By arranging the upper adjusting mechanism, the flow path of the gas in the rectangular frame can be adjusted according to the concentration of NMP in the gas, 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 the dissolved water on NMP, and the adjustment can be flexibly made according to the actual situation.

[0019] 2、The present application can be opened when the NMP concentration in the gas is deeper through the setting of the lower adjusting mechanism, so as to play a flow resistance effect on the flow rate of the gas in the rectangular frame, and further increase the residence time of the gas in the rectangular frame in cooperation with the upper adjusting mechanism, and further improve the dissolution effect of the dissolved water on the NMP. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the overall structure schematic diagram of the NMP recovery and purification system of the present application;

[0021] Figure 2 It is the rear view three-dimensional structure schematic diagram of the recovery tower of the present application;

[0022] Figure 3 It is the front view partial cutaway three-dimensional structure schematic diagram of the recovery tower of the present application;

[0023] Figure 4 It is the front view full cutaway three-dimensional structure schematic diagram of the rectangular frame of the present application;

[0024] Figure 5 It is the side view three-dimensional structure schematic diagram of the rectangular frame of the present application;

[0025] Figure 6 It is the top view full cutaway three-dimensional structure schematic diagram of the rectangular frame of the present application;

[0026] Figure 7 It is the overall appearance structure schematic diagram of the rotating cylinder and the shielding cloth of the present application;

[0027] Figure 8 It is the three-dimensional structure schematic diagram of the adjusting block, the flow separation block and the disc of the present application;

[0028] Figure 9 It is the flow direction schematic diagram of the guide groove duct of the present application.

[0029] In the figure: 1, recovery tower; 2, coarse dehydration tower; 3, partition wall tower; 4, rectification assembly; 5, rectangular frame; 6, air inlet pipe; 7, NMP concentration sensor; 8, spraying mechanism; 9, upper adjusting rod; 10, lower adjusting rod; 11, winding roller; 12, upper pull rope; 13, guide roller; 14, lower pull rope; 15, shielding cloth; 16, winding motor; 17, volute spring; 18, support plate; 19, rotating cylinder; 20, air outlet; 21, right angle plate; 22, right angle block; 23, adjusting block; 24, guide groove; 25, flow separation block; 26, adjusting motor; 27, top frame; 28, disc; 29, protruding block; 30, storage groove; 31, plugging plate; 32, round rod; 33, corrugated cover; 34, upper spring; 35, drainage groove. DETAILED DESCRIPTION

[0030] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the invention is not limited to the specific embodiments disclosed below.

[0032] like Figures 1-9 The system shown uses a thermally coupled partitioned wall tower to recover and purify NMP, including a recovery tower 1, a crude dehydration tower 2, and a partitioned wall tower 3 arranged sequentially. The bottom material collection pipeline of the recovery tower 1 is connected to the crude dehydration tower 2 and the partitioned wall tower 3. The top of the recovery tower 1 is equipped with a monitoring component and a secondary dissolution mechanism to prevent the discharge of gas containing NMP. The partitioned wall tower 3 is equipped with a distillation component 4 for further distillation and purification of NMP. The distillation component 4 includes a central distillation section, a common stripping section (located below the central distillation section), and a common distillation section (located above the central distillation section). A rectangular frame 5 is fixedly connected inside the recovery tower 1. An inlet pipe 6 is fixedly connected to the side wall of the rectangular frame 5 and penetrates the outer wall of the recovery tower 1. An NMP concentration sensor 7 is installed on the inlet pipe 6. A spraying mechanism 8 for spraying the dissolving liquid is installed at the top of the rectangular frame 5. An upper regulating mechanism for adjusting the gas flow path and a lower regulating mechanism for adjusting the gas flow rate are respectively installed inside the rectangular frame 5.

[0033] Before use, set the medium and high concentration alarm values ​​for the NMP concentration sensor 7. Then, when dissolving NMP in the gas, first control the spraying mechanism 8 to start spraying the dissolved water into the rectangular frame 5. Then open the valve to discharge the gas containing NMP into the rectangular frame 5, where it combines with the sprayed water droplets. Due to gravity, the gas is discharged from the outlet 20 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, i.e., 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 coarse dehydration tower 2 for further processing.

[0034] After NMP gas is recovered and treated by recovery tower 1, it is discharged into crude dehydration tower 2 through pipeline. The NMP containing water to be treated first enters crude dehydration tower 2 for dehydration. Under negative pressure operation conditions, by controlling the reflux ratio and reflux temperature at the top of the tower, a large amount of water is collected from the top of the tower, and a crude NMP product with low water content (1%) is collected from the bottom of the tower. It enters the adjacent tower 3 and enters the middle of the pre-separation section of the middle rectification section in the rectification component 4. The top of this tower collects low-boiling substances (mainly water or water-containing NMP), which can be returned to crude dehydration tower 2 for mixing. The bottom of the tower collects high-boiling substances (PVDF). The main separation section of the middle rectification section collects high-purity NMP and discharges it.

[0035] The upper adjusting mechanism comprises a pair of upper adjusting rods 9 arranged inside the rectangular frame 5 and a lower adjusting rod 10 arranged between the upper adjusting rods 9. A pair of winding rollers 11 are rotatably connected inside the recycling tower 1. A pair of upper pull ropes 12 are fixedly connected to the side walls of the lower adjusting rod 10, and the other ends of the upper pull ropes 12 are fixedly connected to the outer walls of the winding rollers 11 by winding through the outer walls of the rectangular frame 5. A pair of lower pull ropes 14 are fixedly connected to the side walls of the upper adjusting rods 9, and the other ends of the lower pull ropes 14 are fixedly connected to the winding rollers 11 by winding through the outer walls of the rectangular frame 5. A pair of guide rollers 13 are rotatably connected inside the rectangular frame 5. The guide rollers 13 guide the sliding direction of the lower pull ropes 14 and improve the silkiness during the pulling of the lower pull ropes 14. The lower pull ropes 14 are arranged in a U-shaped manner inside the rectangular frame 5 by passing through the outer walls of the guide rollers 13. The upper adjusting rods 9 and the lower adjusting rod 10 are fixedly connected to the shielding cloth 15 away from one side. The outer walls of the rectangular frame 5 are provided with a reset mechanism for pulling the shielding cloth 15 back to its original position. The side walls of the rectangular frame 5 and away from the air inlet pipe 6 are provided with an air outlet 20.

[0036] The outer walls of the recycling tower 1 and corresponding to the winding rollers 11 are fixedly connected with winding motors 16. The output ends of the winding motors 16 are fixedly connected with the side walls of the winding rollers 11 by passing through the inner walls of the recycling tower 1. The winding motors 16 are electrically connected with the NMP concentration sensor 7 through the controller.

[0037] The reset mechanism comprises a pair of support plates 18 fixedly connected to the outer walls of the rectangular frame 5 and corresponding to the shielding cloth 15. A rotating cylinder 19 is rotatably connected between the support plates 18. The other ends of the shielding cloth 15 are fixedly connected to the rotating cylinder 19 by winding through the outer walls of the rectangular frame 5. Three volute springs 17 are arranged inside the rotating cylinder 19. One end of each volute spring 17 is fixedly connected to the side walls of the support plates 18, and the other end of each volute spring 17 is fixedly connected to the inner walls of the rotating cylinder 19.

[0038] When the NMP concentration sensor 7 detects a medium concentration, it will control the winding motor 16 to start rotating the winding roller 11, thereby winding the upper pull rope 12 and the lower pull rope 14 on 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 adjusting rod 9 and the lower adjusting rod 10 will slide inside the rectangular frame 5 under the guidance of the guide roller 13, and the shielding cloth 15 will be pulled out of the rotating cylinder 19. At the same time, since the other end of the shielding cloth 15 is fixed to the rotating cylinder 19, the rotating cylinder 19 will also rotate during the pulling of the shielding cloth 15. Since one end of the volute spring 17 is fixed to the inner wall of the rotating cylinder 19 and the other end is fixed to the side wall of the support plate 18, the rotating cylinder 19 will also rotate during the pulling of the shielding cloth 15.

[0039] Therefore, by rotating the cylinder 19, the scroll spring 17 is gradually compressed, and then the upper adjusting rod 9 is pulled to the side of the guide roller 13, and the lower adjusting rod 10 is pulled to the designated position (at this time, the lower adjusting rod 10 has a certain distance from the inner wall of the rectangular frame 5, and the distance between the upper adjusting rod 9 and the inner wall of the rectangular frame 5 is the same), so that the shielding cloth 15 is completely opened, and an S-shaped channel is formed in the rectangular frame 5 through the shielding cloth 15, which blocks the gas discharged from the air inlet pipe 6, thereby increasing the residence time of the gas in the rectangular frame 5 when the NMP concentration in the gas is deepened, thereby improving the dissolution effect of the dissolved water on the NMP, and the actual situation can be flexibly adjusted. Finally, when retracted, control the reverse start of the winding motor 16 to reverse the above operation.

[0040] In order to facilitate the dissolved water sprayed to be quickly discharged from the air outlet 20, the rectangular frame 5 is fixedly connected with a right-angle plate 21 with an inclined surface at the bottom, and the lowest end of the inclined surface of the right-angle plate 21 is arranged near the air outlet 20. Through the arrangement of the right-angle plate 21, the flow of the dissolved water in the rectangular frame 5 is facilitated, and the dissolved water is quickly discharged from the inside of the rectangular frame 5, avoiding accumulation in the rectangular frame 5. The inside of the rectangular frame 5 and the air inlet pipe 6 are fixedly connected with a right-angle block 22 with an inclined surface for flow guiding. Through the arrangement of the right-angle block 22, the gas discharged from the air inlet pipe 6 can be guided, avoiding being directly blown to the air outlet 20, further improving the recovery effect of the device. A plurality of drainage grooves 35 are equally arranged at the bottom of the adjusting block 23 and the bottom of the flow blocking block 25. Through the arrangement of the drainage grooves 35, the dissolved water in the rectangular frame 5 is prevented from being blocked by the adjusting block 23, further facilitating the discharge of the dissolved water.

[0041] In order to be able to block the flow of gas in the rectangular frame 5, the lower adjusting mechanism includes a pair of adjusting blocks 23. The adjusting blocks 23 are fixedly connected to the inner side of the rectangular frame 5. The adjusting blocks 23 are flush with the side of the upper adjusting rod 9. The adjusting blocks 23 are provided with a pair of half-heart-shaped flow guiding grooves 24. The directions of the flow guiding grooves 24 are opposite. The flow guiding grooves 24 are provided with water drop-shaped flow blocking blocks 25. The flow blocking blocks 25 are fixedly connected to the inner side of the rectangular frame 5. The flow blocking blocks 25 and the flow guiding grooves 24 are combined to form a channel for the gas to pass through. The adjusting block 23 is provided with a plugging mechanism for plugging the channel. The NMP concentration sensor 7 is electrically connected to the plugging mechanism through the controller.

[0042] The blocking mechanism comprises an adjusting motor 26, the top of the rectangular frame 5 is fixedly connected with a top frame 27, the top of the rectangular frame 5 is rotatably connected with a disc 28, the adjusting motor 26 is fixedly connected to the top of the top frame 27, the output end of the adjusting motor 26 is fixedly connected to the top end of the disc 28 through the top of the top frame 27, 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 provided as a curved surface, the top of each adjusting block 23 is provided with a receiving groove 30, the inside of the receiving groove 30 is slidably connected with a blocking plate 31, the top of the blocking plate 31 is fixedly connected with a circular rod 32, and the top end of the circular rod 32 is arranged to penetrate through the top of the rectangular frame 5, and the top of the rectangular frame 5 is provided with a sliding groove corresponding to the circular rod 32, and the outer wall of the disc 28 is in contact with the circular rod 32;

[0043] When the NMP concentration sensor 7 detects a high concentration, the adjusting motor 26 is controlled to start and drive the disc 28 to rotate, thereby driving the protruding block 29 to rotate and extrude the circular rod 32 to move, so as to push the blocking plate 31 to slide in the receiving groove 30, and gradually compress the upper spring 34, thereby opening the channel, facilitating the gas guided by the upper adjusting mechanism to pass through the channel. At this time, part of the gas will enter the channel, and the other part of the gas will pass through the original flow blocking block 25 and then come out of the channel. The gas coming out of the channel will flow back and collide with the gas passing through the flow blocking block 25, and the force after the collision will weaken the flow rate of the gas. After two collisions, the flow rate of the gas will be greatly weakened, thereby achieving the effect of blocking the flow of the gas 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 the dissolved water on the NMP.

[0044] In order to avoid the gas in the rectangular frame 5 from being discharged into the top frame 27, a corrugated cover 33 is fixedly connected between the inside of the sliding groove and the outer wall of the circular rod 32. Through the arrangement of the corrugated cover 33, the normal sliding of the circular rod 32 is not hindered, and the sliding groove is blocked, avoiding 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 inside of the receiving groove 30 and the side wall of the blocking plate 31. Through the arrangement of the upper spring 34, when the adjusting motor 26 drives the disc 28 to reverse and remove the extrusion of the circular rod 32, the circular rod 32 and the blocking plate 31 are quickly pushed to reset under the elastic force of the upper spring 34, thereby maintaining the blocking of the channel.

[0045] The above shows and describes the basic principles, main features and advantages of the present application.

[0046] Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A system for recovering and purifying NMP by thermally coupled divided wall columns, characterized in that: Including recovery tower (1), crude dehydration tower (2) and partition wall tower (3) arranged in turn backward, the partition wall tower (3) is equipped with rectification assembly (4) for further rectification and purification of NMP, the recovery tower (1) is fixedly connected with rectangular frame (5) inside, the side wall of rectangular frame (5) is fixedly connected with air inlet pipe (6), and the air inlet pipe (6) is arranged through the outer wall of recovery tower (1), and the air inlet pipe (6) is provided with NMP concentration sensor (7), the inside top of rectangular frame (5) is provided with spraying mechanism (8) for spraying dissolving solution, the inside of rectangular frame (5) is respectively provided with upper adjusting mechanism for adjusting gas flow route and lower adjusting mechanism for adjusting gas flow velocity, The upper adjusting mechanism includes upper adjusting rod (9) and lower adjusting rod (10), the upper adjusting rod (9) is provided with a pair, the upper adjusting rod (9) is arranged inside the rectangular frame (5), the lower adjusting rod (10) is arranged between the upper adjusting rod (9), the inside of the recovery tower (1) is rotatably connected with a pair of winding rollers (11), the side wall of the lower adjusting rod (10) is fixedly connected with a pair of upper pull ropes (12), and the other end of the upper pull rope (12) is fixedly connected on the outer wall of the winding roller (11) by winding through the outer wall of the rectangular frame (5), the side wall of the upper adjusting rod (9) is fixedly connected with a pair of lower pull ropes (14), and the other end of the lower pull rope (14) is fixedly connected on the winding roller (11) by winding through the outer wall of the rectangular frame (5), the inside of the rectangular frame (5) is rotatably connected with a pair of guide rollers (13), the lower pull rope (14) is arranged in the rectangular frame (5) in U-shaped form by passing through the outer wall of the guide roller (13), the upper adjusting rod (9) and the lower adjusting rod (10) are fixedly connected with the shielding cloth (15) away from one side, the outer wall of the rectangular frame (5) is provided with a reset mechanism for pulling the shielding cloth (15) to reset, and the side wall of the rectangular frame (5) and away from the air inlet pipe (6) side is provided with air outlet (20).

2. The system for recycling and purifying NMP by using thermally coupled dividing wall column according to claim 1, characterized in that: The outer wall of the recovery tower (1) and the corresponding position of the winding roller (11) are fixedly connected with winding motor (16), and the output end of the winding motor (16) is fixedly connected with the winding roller (11) through the inner wall of the recovery tower (1), and the winding motor (16) is electrically connected with the NMP concentration sensor (7) through the controller.

3. The system for recycling and purifying NMP by using thermally coupled dividing wall column according to claim 1, characterized in that: The reset mechanism includes spiral spring (17), the outer wall of the rectangular frame (5) and the corresponding position of the shielding cloth (15) are fixedly connected with a pair of supporting plates (18), the supporting plates (18) are rotatably connected with rotating cylinder (19) between them, the other end of the shielding cloth (15) is fixedly connected on the rotating cylinder (19) by winding through the outer wall of the rectangular frame (5), the spiral spring (17) is provided with three, and the three spiral springs (17) are arranged inside the rotating cylinder (19), one end of the spiral spring (17) is fixedly connected on the side wall of the supporting plate (18), and the other end of the spiral spring (17) is fixedly connected on the inner wall of the rotating cylinder (19).

4. The system for recycling and purifying NMP by using thermally coupled dividing wall column according to claim 1, characterized in that: The inner bottom of the rectangular frame (5) is fixedly connected with a right-angle plate (21) with an inclined surface, 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).

5. The system for recovering and purifying NMP by using thermally coupled dividing wall column according to claim 1, characterized in that: The inner side of the rectangular frame (5) and beside the air inlet pipe (6) is fixedly connected with a right-angle block (22) with an inclined surface for flow guiding.

6. The system for recovering and purifying NMP by using thermally coupled dividing wall column according to claim 1, characterized in that: The lower adjusting mechanism comprises adjusting blocks (23), the adjusting blocks (23) are arranged in pairs, the adjusting blocks (23) are fixedly connected to the inner side of the rectangular frame (5) and the middle part, and the side away from the adjusting blocks (23) is flush with the side close to the upper adjusting rod (9). The side close to the adjusting blocks (23) is provided with half-heart-shaped flow guide grooves (24), and the directions of the flow guide grooves (24) are opposite. The inner sides of the flow guide grooves (24) are provided with water drop-shaped flow barriers (25), the flow barriers (25) are fixedly connected to the inner side of the rectangular frame (5), the flow barriers (25) and the flow guide grooves (24) are combined to form a gas passing channel, the adjusting blocks (23) are provided with a plugging mechanism for plugging the channel, and the NMP concentration sensor (7) is electrically connected with the plugging mechanism through a controller.

7. The system for recycling and purifying NMP by using thermally coupled dividing wall column according to claim 6, characterized in that: The plugging mechanism comprises an adjusting motor (26), the top of the rectangular frame (5) is fixedly connected with a top frame (27), the top of the rectangular frame (5) is rotatably connected with a disc (28), the adjusting motor (26) is fixedly connected to the top of the top frame (27), the output end of the adjusting motor (26) is fixedly connected to the top end of the disc (28) through the top of the top frame (27), the outer wall of the disc (28) is fixedly connected with a pair of protruding blocks (29), the outer wall of the protruding blocks (29) is provided with an arc surface, the top of the adjusting blocks (23) is provided with receiving grooves (30), the inner side of the receiving grooves (30) is slidably connected with a plugging plate (31), the top of the plugging plate (31) is fixedly connected with a circular rod (32), and the top end of the circular rod (32) penetrates through the top of the rectangular frame (5) and is arranged, the top of the rectangular frame (5) and the corresponding position of the circular rod (32) are provided with a sliding groove, and the circular rod (32) is in contact with the outer wall of the disc (28).

8. The system for recycling and purifying NMP by using thermally coupled dividing wall column according to claim 7, characterized in that: The inner side of the sliding groove and the outer wall of the circular rod (32) are fixedly connected with a corrugated cover (33), and the inner side of the receiving groove (30) and the side wall of the plugging plate (31) are fixedly connected with a plurality of upper springs (34).

9. The system for recycling and purifying NMP by using thermally coupled dividing wall column according to claim 6, characterized in that: The bottom of the adjusting block (23) and the bottom of the flow barrier (25) are provided with a plurality of drainage grooves (35) at equal intervals.

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