NMP purification process based on NMP rectification system

Abstract

The invention provides an NMP (N-Methyl Pyrrolidone) purification process based on an NMP rectification system, the process is completed by matching a tail gas desorption tower, the space in the tower is divided into an adsorption bin and a desorption bin by arranging a middle box body, two groups of adsorption devices capable of alternately entering the two bins are mounted, and automatic switching of the adsorption devices is realized by utilizing a driving mechanism; when the adsorption efficiency of one group of adsorption devices is reduced, the adsorption devices are automatically transferred to the desorption bin for regeneration treatment, meanwhile, the other group of adsorption devices enter the adsorption bin to continue working, and in the desorption process, low-pressure saturated steam and hot nitrogen are adopted for purging, so that residual moisture is effectively removed, and the adsorption activity is recovered; compared with the prior art, the process has the advantages that gas exchange in the adsorption and desorption process is reduced, the sealing performance and the air pressure balance control capability of the system are improved, the process ensures continuous production, meanwhile, the energy consumption and the discharge pressure are remarkably reduced, and the NMP purification efficiency and the product quality are improved.

Description

Technical Field

[0001] This invention relates to the field of NMP purification technology, specifically to an NMP purification process based on an NMP distillation system. Background Technology

[0002] N-Methyl-2-pyrrolidone (NMP) is a highly efficient polar aprotic solvent with low toxicity, a high boiling point (202℃), and strong solubility. It is widely used in lithium-ion battery cathode slurries, semiconductor cleaning, and polymer synthesis. Industrial-grade NMP often contains impurities such as water, low-boiling-point substances (e.g., toluene), and high-boiling-point substances (e.g., metal complexes). It needs to be purified to electronic grade (purity ≥99.9%) through distillation to meet the stringent solvent requirements of high-end industries.

[0003] The NMP purification process mainly includes three stages: pretreatment (filtration and decolorization), dehydration distillation (vacuum separation of water and low-boiling substances), and main distillation (removal of high-boiling substances). The tail gas generated during the N-methylpyrrolidone (NMP) distillation purification process often contains residual solvents. Traditional treatment methods often employ alternating operation of dual adsorption towers or shutdown for regeneration, resulting in problems such as large equipment footprint, high operating costs, and production interruptions. Especially during the adsorbent regeneration stage, cross-contamination of gases easily occurs during switching, leading to a decrease in purification efficiency. While existing single-tower structures can reduce space occupation, they cannot achieve seamless integration of adsorption and regeneration, still requiring frequent start-ups and shutdowns, affecting continuous production. Furthermore, insufficient sealing and pressure balance control in the tail gas treatment system further exacerbate energy consumption and emission pressure. Therefore, a highly efficient and integrated NMP purification process is urgently needed to solve the problems of gas pollution and energy consumption while ensuring continuous production.

[0004] Therefore, we propose an NMP purification process based on an NMP distillation system. Summary of the Invention

[0005] The purpose of this invention is to provide an NMP purification process based on an NMP distillation system to overcome the above-mentioned shortcomings in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an NMP purification system, comprising a shell and an adsorption chamber disposed within the shell, and an exhaust pipe connected to the adsorption chamber is disposed on the shell; the NMP purification system further comprises:

[0007] An intermediate chamber is set inside the shell and forms a partition between the internal space of the shell. A desorption chamber is formed on the side of the intermediate chamber away from the adsorption chamber inside the shell.

[0008] Two sets of adsorption devices are installed in the housing via a drive mechanism. The drive mechanism is used to make the two sets of adsorption devices alternately enter the adsorption chamber and the desorption chamber, so that while one set of adsorption devices is in the desorption chamber to adsorb and purify the exhaust gas, the other set of adsorption devices is desorbed.

[0009] A hollow tube is installed inside the intermediate chamber, with a piston inside. Both ends of the hollow tube are sealed with plugs, and a frame is installed on the outer surface of the hollow tube. A connecting channel for the adsorption device is formed within the frame. The hollow tube is connected to the adsorption chamber and the desorption chamber respectively through two exhaust pipes, and the hollow tube is also connected to the connecting channel through a one-way valve. A transmission mechanism connected to the piston is installed on the surface of the hollow tube located in the connecting channel. When the two sets of adsorption devices alternate, the piston is driven to move inside the hollow tube through the transmission mechanism to change the gas pressure, so that the gas in the connecting channel is transported to the corresponding adsorption chamber / desorption chamber.

[0010] As a further description of the above technical solution: the adsorption device includes a mounting frame mounted on a driving mechanism and an adsorption material filled in the mounting frame. The width of the mounting frame is the same as the width of the connecting channel. After the driving mechanism moves the mounting frame into place, the end of the mounting frame seals the opening of the connecting channel.

[0011] As a further description of the above technical solution: the two ends of the mounting frame along the direction of movement are respectively provided with sealing plate one and sealing plate two by springs. Both sealing plate one and sealing plate two are made of fluororubber material and their width and height dimensions are greater than the height and width dimensions of the ends of the mounting frame.

[0012] As a further description of the above technical solution: both exhaust pipes have covers installed at their opening positions inside the hollow pipe via torsion springs. The openings of the covers are equipped with receiving rollers via torsion springs, and a traction belt with one end fixed to a sliding plate is wound around the receiving rollers. The sliding plate is slidably mounted on the upper surface of the covers, and when the covers are in the closed state, the upper surface of the covers is flush with the lower surface inside the hollow pipe.

[0013] The hollow tube has triangular plates at both ends, and the piston has an inclined surface with the same tilt angle as the triangular plates on its bottom side.

[0014] As a further description of the above technical solution: the hollow tube has grooves on the top side near the two ends, and the piston is connected to two sealing plugs through a telescopic rod.

[0015] As a further description of the above technical solution: the transmission mechanism includes two sets of fixed wheels fixed on the surface of the hollow tube and two sets of movable wheels slidably disposed on the surface of the hollow tube, and a pull rope is wound on both the fixed wheels and the movable wheels, and the end of the pull rope is fixedly disposed on the surface of the intermediate box. The frames of the two movable wheels are inserted into the hollow tube through connecting rods and slidably connected to the piston surface. A contact block is disposed on the pull rope between the two sets of fixed wheels through a torsion spring.

[0016] As a further description of the above technical solution: the sealing method at the position where the connecting rod passes through the sealing plug and the intermediate housing is a dynamic seal.

[0017] As a further description of the above technical solution: a protrusion is provided on the surface of the hollow tube in the connecting channel, and inclined grooves are opened at both ends of the protrusion surface. A straight groove with a slide seat is slidably installed between the two inclined grooves. The slide seat is connected to the abutment block, and a guide plate is provided on the protrusion near the inclined groove. The guide plate is inserted into the groove along the inclined direction until it is inside the groove. The guide plate is made of elastic material, and the distance between the end of the guide plate and the straight groove is smaller than the size of the end of the slide seat.

[0018] As a further description of the above technical solution: the ends of the inclined groove and the straight groove are connected by a groove opening perpendicular to the straight groove.

[0019] An NMP purification process based on an NMP distillation system, applied to the aforementioned NMP purification system, is characterized by comprising the following steps:

[0020] S1: The tail gas generated by the NMP purification of the NMP distillation system is passed into the adsorption chamber inside the shell. The residual solvent in the tail gas is adsorbed by the adsorption device, and then the tail gas after adsorption treatment is discharged through the discharge pipe.

[0021] S2: When the adsorption efficiency of one set of adsorption devices decreases, the drive device is activated, causing the adsorption device in the adsorption chamber to enter the desorption chamber, and at the same time, the adsorption device in the desorption chamber to enter the adsorption chamber.

[0022] S3: Introduce low-pressure saturated steam (pressure 0.5MPa, temperature 120-150℃) into the desorption chamber for 30-60 minutes, then purge with hot nitrogen (80-100℃) for 10-20 minutes to remove residual moisture and restore adsorption activity.

[0023] S4: Repeat steps S2 to S3.

[0024] In the above technical solution, the NMP purification process based on an NMP distillation system provided by the present invention has the following beneficial effects:

[0025] High-efficiency continuous production: By using two sets of adsorption devices alternately, a seamless connection between adsorption and regeneration is achieved, avoiding the problem of equipment shutdown for regeneration in traditional methods, and ensuring the continuity and efficiency of the NMP purification process.

[0026] Reduced energy consumption and emissions: By incorporating hollow tubes and pistons, this invention effectively reduces gas exchange during adsorption and desorption processes, improves the system's sealing and pressure balance control capabilities, thereby reducing energy consumption and emissions. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0028] Figure 1 This is a schematic diagram of the overall structure provided for an embodiment of the present invention;

[0029] Figure 2 This is a structural schematic diagram of the top view cross-section provided in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the overall structure after removing the shell, provided in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the cross-section of the entire structure after removing the shell, as provided in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the connection channel provided in an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the hollow tube and intermediate box provided in an embodiment of the present invention;

[0034] Figure 7 Provided for embodiments of the present invention Figure 6 Enlarged structural diagram at point A;

[0035] Figure 8 This is a schematic diagram of the suction assembly provided in an embodiment of the present invention;

[0036] Figure 9 This is a structural schematic diagram of a cross-sectional view of a hollow tube provided in an embodiment of the present invention;

[0037] Figure 10 This is a schematic diagram of the structure of the cover provided in an embodiment of the present invention;

[0038] Figure 11This is a schematic diagram of the protrusion structure provided in an embodiment of the present invention;

[0039] Figure 12 Provided for embodiments of the present invention Figure 11 Enlarged structural diagram at point B;

[0040] Figure 13 This is a top view of the hollow tube structure provided in an embodiment of the present invention.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Shell; 2. Discharge pipe; 3. Connecting frame; 31. Conveying device; 4. Adsorption chamber; 5. Desorption chamber; 6. Intermediate box; 7. Exhaust pipe; 71. Connecting rod; 72. Sealing plug; 73. Hollow tube; 75. Fixed wheel; 76. Pull rope; 77. Movable wheel; 78. Abutment block; 79. Groove; 710. Piston; 711. Telescopic rod; 712. Triangular plate; 713. One-way valve; 714. Notch; 715. Cover; 716. Slide plate; 719. Collection roller; 8. Sealing plate one; 81. Sealing plate two; 82. Spring; 9. Mounting frame; 91. Adsorption material; 10. Connecting channel; 11. Frame; 12. Protrusion; 121. Straight groove; 122. Guide plate; 123. Inclined groove; 124. Slide seat. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0044] Please see Figures 1-13 This invention provides an NMP purification system, including a housing 1 and an adsorption chamber 4 disposed within the housing 1. An exhaust pipe 2 connected to the adsorption chamber 4 is provided on the housing 1 to allow the exhaust gas generated by the NMP purification process to be introduced into the adsorption chamber 4 within the housing 1, so that the exhaust gas adsorbs the residual solvent through the adsorption chamber 4, preventing direct discharge and pollution.

[0045] The NMP purification unit based on the NMP distillation system also includes:

[0046] An intermediate box 6 is set inside the shell 1 and forms a partition between the internal space of the shell 1. A desorption chamber 5 is formed on the side of the intermediate box 6 away from the adsorption chamber 4 inside the shell 1.

[0047] Two sets of adsorption devices are installed inside the housing 1 via a drive mechanism. This drive mechanism allows the two sets of adsorption devices to alternately enter the adsorption chamber 4 and the desorption chamber 5. This allows one set of adsorption devices to adsorb and purify the exhaust gas while the other set of adsorption devices performs desorption. An intermediate box 6 is provided inside the housing 1, dividing the internal space into adsorption chamber 4 and desorption chamber 5. Two sets of adsorption devices are provided, located in adsorption chamber 4 and desorption chamber 5 respectively. When the adsorption device in adsorption chamber 4 becomes saturated, the drive mechanism is activated, causing the two adsorption devices to switch positions. The saturated adsorption device then enters the desorption chamber 5, and low-pressure saturated steam (pressure 0.5 MPa, temperature 120-150℃) is introduced into the desorption device. Continue for 30-60 minutes, then purge with hot nitrogen (80-100℃) for 10-20 minutes to remove residual moisture and restore the adsorption activity of the adsorption device. In this way, when the other adsorption device is saturated, the above process is repeated, and the positions of the two adsorption devices can be switched back and forth. There is no need to shut down the entire machine after the adsorption material 91 in the adsorption tower is saturated, which would reduce production efficiency. There is also no need to use a dual adsorption tower design, which occupies a large space. By setting up two sets of adsorption devices and having the two sets of adsorption devices alternately enter the adsorption chamber 4 to adsorb the tail gas and enter the desorption chamber 5 to desorb it, the treatment of tail gas can be carried out continuously, improving production efficiency. Moreover, the shell 1 integrates two adsorption devices that can be changed in position, which is compact, convenient to use, and suitable for widespread use.

[0048] In one embodiment of the present invention, the driving mechanism includes a conveying device 31 disposed in the housing 1. The conveying device 31 is a belt conveyor, and the upper surface and lower surface of the belt conveyor are respectively connected to two adsorption devices through a connecting frame 3. In this way, after the driving mechanism is started, the upper and lower belts of the belt conveyor move in opposite directions, realizing the operation of one adsorption device entering the desorption chamber 5 and the other adsorption device entering the adsorption chamber 4.

[0049] To reduce gas exchange between the desorption chamber 5 and the adsorption chamber 4 when switching between the two adsorption devices, the NMP purification device based on the NMP distillation system also includes a hollow tube 73 set in the intermediate box 6. A piston 710 is set inside the hollow tube 73, and the two ends of the hollow tube 73 are sealed by sealing plugs 72. A frame 11 is set on the outer surface of the hollow tube 73, and a connecting channel 10 for the adsorption device to pass through is formed in the frame 11. The hollow tube 73 is connected to the adsorption chamber 4 and the desorption chamber 5 respectively through two exhaust pipes 7, and the hollow tube 73 is also connected to the connecting channel 10 through a one-way valve 713. A transmission mechanism connected to the piston 710 is set on the surface of the hollow tube 73 located in the connecting channel 10. When the two sets of adsorption devices are switched, the piston 710 is driven by the transmission mechanism to move in the hollow tube 73 to change the gas pressure, so that the gas in the connecting channel 10 is transported to the corresponding adsorption chamber 4 / desorption chamber 5.

[0050] The adsorption device includes a mounting frame 9 mounted on a drive mechanism and an adsorption material 91 filled in the mounting frame 9. The width of the mounting frame 9 is the same as the width of the connecting channel 10. After the drive mechanism moves the mounting frame 9 into place, the end of the mounting frame 9 seals the opening of the connecting channel 10.

[0051] When the drive mechanism is activated to switch the positions of the two adsorption devices, there are two states: The mounting frame 9 of the adsorption device in the adsorption chamber 4 is pulled by the drive mechanism towards the desorption chamber 5 through the intermediate housing 6. At this time, the exhaust gas in the adsorption chamber 4 enters the connecting channel 10 through the gaps between the adsorption materials 91 in the mounting frame 9. However, since the width of the mounting frame 9 is the same as the width of the connecting channel 10, the exhaust gas cannot directly enter the desorption chamber; it only enters the connecting channel 10. As the mounting frame 9 moves within the connecting channel 10, after it is fully inserted, the connecting channel 10 is no longer connected to either the adsorption chamber 4 or the desorption chamber 5. At this point, the mounting frame 9 abuts against the transmission mechanism, causing the piston 710 to move within the hollow tube 73, changing the hollow tube's position. The pressure on one side of the piston 710 inside the tube 73 is used to draw the gas between the mounting brackets 9 in the connecting channel 10 through the one-way valve 713, thereby drawing the exhaust gas entering the connecting channel 10 from the adsorption chamber 4 into the hollow tube 73. As the external drive mechanism moves, one end of the mounting bracket 9 disengages from the connecting channel 10, and the adsorption material 91 enters the desorption chamber 5. However, due to the suction of the piston 710 and the hollow tube 73, this part of the exhaust gas will not enter the desorption chamber 5, preventing pollution. The process of another adsorption device in the desorption chamber 5 entering the adsorption chamber 4 is the same, except that the vapor entering the desorption chamber 5 from the connecting channel 10 is drawn into the hollow tube 73, thereby preventing gas exchange between the adsorption chamber 4 and the desorption chamber 5, preventing pollution, and improving the overall performance.

[0052] After the two adsorption devices are moved into place, the ends of the mounting frame 9 do not detach from the connecting channel 10, thereby sealing the opening of the connecting channel 10 and further preventing gas exchange between the desorption chamber 5 and the adsorption chamber 4. To further improve this effect, the two ends of the mounting frame 9 along the direction of movement are respectively equipped with sealing plate 1 8 and sealing plate 2 81 by spring 82. The sealing plate 1 8 and sealing plate 2 81 are both made of fluororubber and their width and height dimensions are larger than the height and width dimensions of the ends of the mounting frame 9. When the mounting frame 9 is fully inserted into the connecting channel 10, the sealing plate 1 8 and sealing plate 2 81 will be blocked by the opening of the connecting channel 10, and the spring 82 will be stretched and deformed. At this time, the opening of the connecting channel 10 is sealed by the sealing plate 1 and sealing plate 2 made of fluororubber, preventing the gas in the desorption chamber 5 and the adsorption chamber 4 from entering the connecting channel 10. As a safety measure, this further prevents the problem of gas exchange.

[0053] In another embodiment of the present invention, the transmission mechanism includes two sets of fixed wheels 75 fixed on the surface of the hollow tube 73 and two sets of movable wheels 77 slidably disposed on the surface of the hollow tube 73. A pull rope 76 is wound on both the fixed wheels 75 and the movable wheels 77. The end of the pull rope 76 is fixedly disposed on the surface of the intermediate box 6. The frame of the two movable wheels 77 is inserted into the hollow tube 73 through a connecting rod 71 and slidably connected to the surface of the piston 710. A contact block 78 is provided on the pull rope 76 between the two sets of fixed wheels 75 through a torsion spring.

[0054] After the mounting bracket 9 is fully inserted into the connecting channel 10, the mounting bracket 9 abuts against the contact block 78, and the pull rope 76 is pulled by the contact block 78. Please refer to [link / reference]. Figure 13 At this time, since the pull rope 76 is wound around the fixed wheel 75 and the movable wheel 77, when the pull rope 76 at the position of the two fixed wheels 75 is pulled, the two movable wheels 77 will move on the outer wall of the hollow tube 73 in the opposite direction to the direction in which the pull rope 76 is pushed, thereby pulling the piston 710 through the connecting rod 71, causing the piston 710 to move inside the hollow tube 73, changing the pressure on one side of the piston 710 inside the hollow tube 73, thereby drawing gas in the connecting channel 10 through the one-way valve 713;

[0055] After the gas in the connecting channel 10 is drawn into the hollow tube 73, in order to process the gas in the hollow tube 73, the opening positions of the two exhaust pipes 7 in the hollow tube 73 are each provided with a cover 715 by a torsion spring. The opening of the cover 715 is provided with a receiving roller 719 by a torsion spring, and a traction belt with one end fixed to the slide plate 716 is wound on the receiving roller 719. The slide plate 716 is slidably disposed on the upper surface of the cover 715, and when the cover 715 is in the closed state, the upper surface of the cover 715 is flush with the lower surface of the hollow tube 73. Triangular plates 712 are provided at the two ends of the hollow tube 73, and a notch 714 with the same inclination angle as the triangular plate 712 is opened on the bottom side of the piston 710.

[0056] As piston 710 moves within hollow tube 73, it abuts against sliding plate 716 and pushes it forward. Sliding plate 716 pulls the traction belt, causing the receiving roller 719 to rotate and release the traction belt wound on it. After piston 710 moves to contact the surface of triangular plate 712, the traction belt is released to its maximum length. Piston 710 is slidably positioned at the bottom of hollow tube 73 and on the surface of triangular plate 712. After piston 710 abuts against the surface of triangular plate 712, it slides upwards along the inclined surface of triangular plate 712, causing the traction belt to create the same angle as the inclined surface of triangular plate 712. This will affect the cover 7. A pulling force of 15 equal to the tilt angle of the triangular plate 712 is applied to open the cover 715, thereby connecting the hollow tube 73 to the adsorption chamber 4 / desorption chamber 5 through the exhaust pipe 7. When the adsorption device enters the desorption chamber 5 from the adsorption chamber 4, the cover 715 of the exhaust pipe 7 connected to the adsorption chamber 4 is opened, and the gas is discharged back into the adsorption chamber 4. Conversely, the gas is discharged back into the desorption chamber 5. After the gas in the connecting channel 10 is drawn through the hollow tube 73, the drawn gas can be discharged back into the original adsorption chamber 4 / desorption chamber 5 to prevent cross-mixing of the gases on both sides and causing pollution. This has excellent performance.

[0057] When the cover 715 is opened, to prevent the piston 710 from drawing gas from the adsorption chamber 4 / desorption chamber 5 into the hollow tube 73 through the exhaust pipe 7 during movement, grooves 79 are provided on the top side of the hollow tube 73 near both ends. The piston 710 is connected to two sealing plugs 72 via a telescopic rod 711. That is, when the cover 715 is opened, as the piston 710 moves upward along the triangular plate 712, the piston 710 is below the groove 79. At this time, the gas on both sides of the piston 710 in the hollow tube 73 flows. The movement of the piston 710 cannot change the gas pressure, so the suction effect disappears. When 10 moves along the triangular plate 712, the telescopic rod 711 extends to its maximum stroke, pulling the sealing plug 72 to move. At this time, the air pressure in the hollow tube 73 is changed by the sealing plug 72, thereby accelerating the gas in the hollow tube 73 to be pushed out into the adsorption chamber 4 / desorption chamber 5 through the exhaust pipe 7, preventing gas from remaining in the hollow tube 73. When the positions of the two adsorption devices are exchanged, the gas that enters the connecting channel 10 during the exchange can be drawn into the hollow tube 73, and the drawn gas can also be reintroduced into the original adsorption chamber 4 / desorption chamber 5 to prevent gas exchange from causing pollution, and has a better use effect.

[0058] When the piston 710 moves in the opposite direction, the receiving roller 719 rotates in the opposite direction under the action of the torsion spring to receive the traction belt until the piston 710 passes the cover 715, the slide plate 716 returns to its original position, and the cover 715 closes again.

[0059] It should be noted that the sealing method at the position where the connecting rod 71 passes through the sealing plug 72 and the intermediate housing 6 is a dynamic seal, which allows for sealing even during movement to prevent air leakage. Dynamic sealing is existing technology, and details will not be elaborated here.

[0060] After the piston 710 moves to its maximum stroke, a protrusion 12 is provided on the surface of the hollow tube 73 in the connecting channel 10. An inclined groove 123 is provided at both ends of the surface of the protrusion 12. A straight groove 121 is provided between the two inclined grooves 123, on which a slide block 124 is slidably mounted. The slide block 124 is connected to the abutment block 78. A guide plate 122 is provided on the protrusion 12 near the inclined groove 123. The guide plate 122 is inserted into the straight groove 121 along the inclined direction of the inclined groove 123. The guide plate 122 is made of elastic material, and the distance between the end of the guide plate 122 and the straight groove 121 is smaller than the size of the end of the slide block 124. The ends of the inclined groove 123 and the straight groove 121 are connected by a slot perpendicular to the straight groove 121.

[0061] When the mounting frame 9 pushes the contact block 78, the slide block 124 moves on the straight groove 121. Due to the design of the guide plate 122, when the slide block 124 contacts the guide plate 122, the guide plate 122 has an upward guiding action on the slide block 124, causing the slide block 124 to slide along the inclined groove 123, thereby causing the contact block 78 to rotate until the contact block 78 separates from the mounting frame 9. At this time, the mounting frame 9 passes over the contact block 78, and the contact block 78 returns to its original position through the groove. When the mounting frame 9 moves in the opposite direction, it will push the contact block 78 to move again. At this time, when the slide block 124 contacts the guide plate 122, it will push the guide plate 122 upward, causing the guide plate 122 to deflect upward and deform, allowing the slide block 124 to pass through. This process is repeated to achieve the alternation of the two adsorption devices.

[0062] An NMP purification process based on an NMP distillation system, applied to the aforementioned NMP purification system, includes the following steps:

[0063] S1: The tail gas generated by the NMP purification of the NMP distillation system is introduced into the adsorption chamber 4 inside the shell 1. The residual solvent in the tail gas is adsorbed by the adsorption device, and then the tail gas after adsorption treatment is discharged through the discharge pipe 2.

[0064] S2: When the adsorption efficiency of one set of adsorption devices decreases, the drive device is activated, so that the adsorption device in the adsorption chamber 4 at this time enters the desorption chamber 5, and at the same time, the adsorption device in the desorption chamber 5 enters the adsorption chamber 4.

[0065] S3: Introduce low-pressure saturated steam (pressure 0.5MPa, temperature 120-150℃) into desorption chamber 5 for 30-60 minutes, then purge with hot nitrogen (80-100℃) for 10-20 minutes to remove residual moisture and restore adsorption activity.

[0066] S4: Repeat steps S2 to S3.

[0067] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An NMP purification system, comprising a shell (1) and an adsorption chamber (4) disposed within the shell (1), and an outlet pipe (2) connected to the adsorption chamber (4) disposed on the shell (1), characterized in that, The NMP purification system also includes: An intermediate box (6) is set inside the shell (1) and divides the internal space of the shell (1). A desorption chamber (5) is formed on the side of the intermediate box (6) away from the adsorption chamber (4) inside the shell (1). Two sets of adsorption devices are installed in the housing (1) by a drive mechanism. The drive mechanism is used to make the two sets of adsorption devices alternately enter the adsorption chamber (4) and the desorption chamber (5), so that while one set of adsorption devices is in the desorption chamber (5) to adsorb and purify the exhaust gas, the other set of adsorption devices is desorbed. A hollow tube (73) is installed inside the intermediate box (6). A piston (710) is installed inside the hollow tube (73). The two ends of the hollow tube (73) are sealed by sealing plugs (72). A frame (11) is installed on the outer surface of the hollow tube (73). A connecting channel (10) for the adsorption device to pass through is formed in the frame (11). The hollow tube (73) is connected to the adsorption chamber (4) and the desorption chamber (5) respectively through two exhaust pipes (7). The hollow tube (73) is also connected to the connecting channel (10) through a one-way valve (713). A transmission mechanism connected to the piston (710) is installed on the surface of the hollow tube (73) located in the connecting channel (10). When the two sets of adsorption devices are alternated, the piston (710) is driven to move in the hollow tube (73) through the transmission mechanism to change the air pressure, so that the gas in the connecting channel (10) is transported to the corresponding adsorption chamber (4) / desorption chamber (5).

2. The NMP purification system according to claim 1, characterized in that, The adsorption device includes a mounting frame (9) mounted on a drive mechanism and an adsorption material (91) filled in the mounting frame (9). The width of the mounting frame (9) is the same as the width of the connecting channel (10). After the drive mechanism moves the mounting frame (9) into place, the end of the mounting frame (9) seals the opening of the connecting channel (10).

3. The NMP purification system according to claim 2, characterized in that, The mounting bracket (9) has a sealing plate 1 (8) and a sealing plate 2 (81) respectively provided at its two ends along the direction of movement via springs (82). The sealing plate 1 (8) and the sealing plate 2 (81) are both made of fluororubber and their width and height dimensions are greater than the height and width dimensions of the ends of the mounting bracket (9).

4. The NMP purification system according to claim 3, characterized in that, Both exhaust pipes (7) have covers (715) installed at their openings inside the hollow tube (73) via torsion springs. The openings of the covers (715) are equipped with receiving rollers (719) installed via torsion springs. A traction belt with one end fixed to a sliding plate (716) is wound around the receiving rollers (719). The sliding plate (716) is slidably mounted on the upper surface of the covers (715). When the covers (715) are in the closed state, the upper surface of the covers (715) is flush with the lower inner surface of the hollow tube (73). The hollow tube (73) has two triangular plates (712) at its two ends, and the piston (710) has an inclined surface with the same tilt angle as the triangular plate (712) on its bottom side.

5. The NMP purification system according to claim 4, characterized in that, The hollow tube (73) has grooves (79) on the top side near the two ends, and the piston (710) is connected to two sealing plugs (72) through a telescopic rod (711).

6. The NMP purification system according to claim 5, characterized in that, The transmission mechanism includes two sets of fixed wheels (75) fixed on the surface of the hollow tube (73) and two sets of movable wheels (77) slidably disposed on the surface of the hollow tube (73). A pull rope (76) is wound on the fixed wheels (75) and the movable wheels (77). The end of the pull rope (76) is fixedly disposed on the surface of the intermediate box (6). The frame of the two movable wheels (77) is inserted into the hollow tube (73) through a connecting rod (71) and slidably connected to the surface of the piston (710). A contact block (78) is disposed on the pull rope (76) between the two sets of fixed wheels (75) through a torsion spring.

7. The NMP purification system according to claim 6, characterized in that, The sealing method at the position where the connecting rod (71) passes through the sealing plug (72) and the intermediate box (6) is dynamic sealing.

8. The NMP purification system according to claim 7, characterized in that, A protrusion (12) is provided on the surface of the hollow tube (73) in the connecting channel (10). An inclined groove (123) is provided at both ends of the surface of the protrusion (12). A straight groove (121) on which a slide block (124) is slidably installed is provided between the two inclined grooves (123). The slide block (124) is connected to the abutment block (78). A guide plate (122) is provided on the protrusion (12) near the inclined groove (123). The guide plate (122) is inserted into the groove (121) along the inclined direction of the inclined groove (123). The guide plate (122) is made of elastic material. The distance between the end of the guide plate (122) and the straight groove (121) is smaller than the size of the end of the slide block (124).

9. The NMP purification system according to claim 8, characterized in that, The ends of the inclined groove (123) and the straight groove (121) are connected by a slot perpendicular to the straight groove (121).

10. An NMP purification process based on an NMP distillation system, applied to an NMP purification system according to any one of claims 1 to 9, characterized in that, The NMP purification process based on the NMP distillation system includes the following steps: S1: The tail gas generated by the NMP purification of the NMP distillation system is introduced into the adsorption chamber (4) inside the shell (1), and the residual solvent in the tail gas is adsorbed by the adsorption device. Then the tail gas after adsorption treatment is discharged through the discharge pipe (2). S2: When the adsorption efficiency of one of the adsorption devices decreases, the drive device is activated, so that the adsorption device in the adsorption chamber (4) enters the desorption chamber (5) and the adsorption device in the desorption chamber (5) enters the adsorption chamber (4). S3: Introduce low-pressure saturated steam (pressure 0.5MPa, temperature 120-150℃) into the desorption chamber (5) for 30-60 minutes, then purge with hot nitrogen (80-100℃) for 10-20 minutes to remove residual moisture and restore adsorption activity; S4: Repeat steps S2 to S3.

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