Multi-effect rectification device and method for N-methyl pyrrolidone

Abstract

The invention discloses a multi-effect rectification device for N-methyl pyrrolidone, and belongs to the technical field of rectification devices, the multi-effect rectification device comprises a primary rectification tower and a secondary rectification tower which are connected with a negative pressure dehydration tower, and a heat exchanger is connected between the primary rectification tower and the secondary rectification tower. A first-stage flow adjusting assembly and a second-stage flow adjusting assembly are arranged at the top of the first-stage rectifying tower and the top of the second-stage rectifying tower respectively, the first-stage flow adjusting assembly and the second-stage flow adjusting assembly are the same in structure, one side of the second-stage flow adjusting assembly is connected with a condensing device, and the condensing device is connected with a refrigerating device. One side of the condensing device is connected with a finished product box, and a spraying assembly and a stirring device are arranged in the secondary rectifying tower; the invention discloses a multi-effect rectification device for N-methyl pyrrolidone, which can effectively improve the rectification efficiency and ensure the condensation effect by controlling the speed of steam.

Description

Technical Field

[0001] The invention relates to the technical field of distillation devices, and in particular to a multiple-effect distillation device and method for N-methylpyrrolidone. Background Art

[0002] N-methylpyrrolidone needs to be purified during the production and processing. The existing distillation tower cannot effectively control the distillation steam when condensing N-methylpyrrolidone after distillation. A large amount of distillation steam quickly flows into the condenser and passes through the condenser quickly, affecting its condensation effect. Summary of the invention

[0003] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to provide a multiple-effect distillation device for N-methylpyrrolidone which effectively improves the distillation efficiency and ensures the condensation effect by controlling the speed of steam.

[0004] To achieve this object, the present invention adopts the following technical solutions: The present invention provides a multi-effect distillation device for N-methylpyrrolidone, comprising a primary distillation tower and a secondary distillation tower connected to a negative pressure dehydration tower, a heat exchanger is connected between the primary distillation tower and the secondary distillation tower, a primary flow regulating component and a secondary flow regulating component are respectively arranged on the top of the primary distillation tower and the secondary distillation tower, and the primary flow regulating component and the secondary flow regulating component have the same structure, a condensing device is connected to one side of the secondary flow regulating component, the condensing device is connected to a refrigeration device, and a finished product box is connected to one side of the condensing device, and a spraying component and a stirring device are arranged inside the secondary distillation tower; The spray assembly includes a manifold fixed to the inner wall of the secondary distillation tower through a connecting seat, the manifold is connected to a material receiving chamber through a multi-component manifold, the material receiving chamber is connected to a negative pressure dehydration tower through a feed pipe, and spray heads are evenly distributed around the bottom of the manifold, and driving components for driving the spray heads to rotate are arranged on the four groups of spray heads; The secondary flow regulating assembly includes a regulating box arranged on the top of the secondary distillation tower, the regulating box is rotatably connected to a rotating rod, the bottom of the rotating rod is rotatably connected to a fixed rod, both sides of the bottom of the fixed rod are fixed to the inner wall of the outlet of the secondary distillation tower through support rods, a plurality of groups of annular sleeves rotatably connected to the fixed rod are evenly distributed on the fixed rod, and regulating plates are fixed on the plurality of groups of annular sleeves, a gear group is arranged between the regulating plate and the rotating rod, and the gear group is driven by a motor to control the rotation of the regulating plate to achieve the discharge speed of steam.

[0005] The preferred technical solution of the present invention is that the spray head comprises a spray pipe rotatably connected to the manifold through a rotating joint, the bottom of the spray pipe is connected to a spray cavity, and a plurality of groups of spray heads are arranged at the bottom of the spray cavity.

[0006] The preferred technical solution of the present invention is that the driving component includes a rotating shaft arranged inside the secondary distillation tower, the rotating shaft is rotatably connected to the material receiving chamber, a main gear is arranged on the rotating shaft, a secondary gear meshing with the main gear is arranged on the spray pipe, and a motor is connected to the bottom of the rotating shaft.

[0007] The preferred technical solution of the present invention is that several groups of adjustment plates are distributed in a stepped manner around the fixed rod, and a slide groove is opened on the top; several groups of adjustment plates are provided with a slide rod at the bottom, and the slide rod is located on the slide groove side of the adjacent adjustment plate, and the depth of the slide groove is adapted to the length of the slide rod.

[0008] The preferred technical solution of the present invention is that the tooth group includes a connecting rod arranged on the top of the adjusting plate, the connecting rod is fixed to the top of the adjusting plate at the stepped top, a first gear is arranged on the connecting rod, a second gear meshing with the first gear is arranged on the rotating rod, and the rotating rod is connected to the motor driving end.

[0009] The preferred technical solution of the present invention is that the stirring device includes a stirring frame arranged inside the secondary distillation tower, the stirring frame is fixedly connected to the rotating shaft, stirring rods are evenly distributed around the top of the stirring frame, and a stirring ring is arranged on the stirring rods.

[0010] The preferred technical solution of the present invention is that the condensing device includes two groups of condensing chambers fixed to the inner wall of the condensing box through a socket, and the two groups of condensing chambers are close to each other and are respectively connected to a first annular condensing tube and a second annular condensing tube on one side, and the two groups of condensing chambers are respectively connected to the refrigeration device through a connecting pipe and a reflux pipe.

[0011] A preferred technical solution of the present invention is that the first annular condenser is arranged around the outside of the second annular condenser.

[0012] A multiple-effect distillation method for N-methylpyrrolidone, wherein the multiple-effect distillation method is carried out using a multiple-effect distillation device, and the multiple-effect distillation method comprises the following steps: Step 1: pre-treating the waste liquid raw materials to remove impurities and non-volatile substances in the raw materials; Step 2: Open the control valve, add the pretreated liquid into the negative pressure dehydration tower for dehydration treatment, and the dehydrated liquid is respectively sent to the primary distillation tower and the secondary distillation tower through the feed pipe from the bottom of the negative pressure dehydration tower; Step 3: According to the requirement of steam condensation speed, the speed of steam in the primary distillation tower is adjusted under the action of the primary flow regulating component, so that steam enters the heat exchanger as hot material. At this time, the heat exchanger acts as the condenser of the primary distillation tower, absorbs heat from the primary distillation tower, and transfers the heat to the secondary distillation tower through the heat exchanger. The condensed condensate is partially collected in the finished product box under the action of the reflux pump, and partially refluxes into the primary distillation tower; Step 4: Start the motor and the spray assembly, so that the feed liquid entering the secondary distillation tower is sprayed inside the secondary distillation tower through the spray assembly, and the spray liquid is heated and stirred by the stirring device and the heating device; Step 5: According to the requirement of steam condensation speed, the secondary flow regulating component is adjusted so that the steam enters the condensing device through the condenser at the top for condensation, and is then collected in the finished product box through the conduit. The solution at the bottom of the tower enters the heat exchanger for evaporation as a cold material, and refluxes to the secondary distillation tower through the reflux pipe in the form of a gas-liquid mixture. At this time, the heat exchanger acts as a reboiler of the secondary distillation tower, transferring the heat of the primary distillation tower to the secondary distillation tower.

[0013] The beneficial effects of the present invention are: 1. The present invention is provided with a negative pressure dehydration tower, a primary distillation tower, a secondary distillation tower, a condensing device and a heat exchanger. The heat exchanger can simultaneously serve as a reboiler of the secondary distillation tower and a condenser of the primary distillation tower, thereby achieving effective heat exchange, ensuring distillation efficiency and having a good energy-saving effect; 2. The present invention introduces the dehydrated liquid into the spray assembly, and drives the spray head to rotate under the action of the driving component, so that the liquid is evenly dispersed inside the distillation tower, which can effectively achieve the dispersion of the liquid, make it evaporate quickly, and accelerate the speed of distillation. At the same time, the motor drives the gear group to work. Under the action of the gear group, the adjustment plate rotates around the fixed rod through the annular set. Under the cooperation of the slide bar and the slide groove, one group of adjustment plates drives another group of adjustment plates to rotate in sequence, so as to adjust the speed of steam flowing into the condenser tube and ensure the condensation effect; 3. In order to improve the condensation efficiency of steam, the present invention allows the steam to enter the condensation box through the condenser, and the cooling water flows into the first annular condenser and the second annular condenser respectively, and the first annular condenser is arranged around the outside of the second annular condenser, thereby increasing the contact range with the steam, being able to effectively and quickly condense the steam, achieving the recovery efficiency of the product, and ensuring the condensation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure of a multiple-effect distillation device provided in a specific embodiment of the present invention; Figure 2 It is a schematic diagram of the structure of a two-stage distillation tower provided in a specific embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of a condensing device and a spraying assembly provided in a specific embodiment of the present invention; Figure 4 is a schematic diagram of the structure of a driving component provided in a specific embodiment of the present invention; Figure 5 The structure of the secondary flow regulating component provided in the specific embodiment of the present invention is schematically shown. Figure 1 ; Figure 6 The structure of the secondary flow regulating component provided in the specific embodiment of the present invention is schematically shown. Figure 2 ; Figure 7 It is a schematic diagram of the structure of a condensing device provided in a specific embodiment of the present invention.

[0015] In the accompanying drawings, the components represented by the reference numerals are listed as follows: 1. Negative pressure dehydration tower; 11. Feed pipe; 12. Connecting seat; 2. Primary distillation tower; 3. Secondary distillation tower; 4. Heat exchanger; 5. Condensation device; 51. Refrigeration device; 52. Condensation box; 53. Condensation chamber; 54. First annular condenser; 55. Second annular condenser; 56. Card seat; 6. Finished product box; 7. Secondary flow regulating assembly; 71. Rotating rod; 72. Fixed rod; 73. Annular kit; 74. Adjustment plate; 741. Sliding Groove; 742, slide bar; 75, connecting rod; 76, first gear; 77, second gear; 78, regulating box; 8, spray assembly; 81, collecting chamber; 82, diverter pipe; 83, receiving chamber; 84, spray pipe; 85, spray chamber; 86, nozzle; 87, driving component; 871, rotating shaft; 872, main gear; 873, sub gear; 9, stirring device; 91, stirring frame; 92, stirring rod; 93, stirring ring; 10, motor. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0017] Embodiment 1 See attached Figure 1-6 , a multi-effect distillation device for N-methylpyrrolidone, comprising a primary distillation tower 2 and a secondary distillation tower 3 connected to a negative pressure dehydration tower 1, a heat exchanger 4 is connected between the primary distillation tower 2 and the secondary distillation tower 3, a primary flow regulating component and a secondary flow regulating component 7 are respectively arranged on the top of the primary distillation tower 2 and the secondary distillation tower 3, and the primary flow regulating component and the secondary flow regulating component 7 have the same structure, a condensing device 5 is connected to one side of the secondary flow regulating component 7, the condensing device 5 is connected to a refrigeration device 51, and a finished product box 6 is connected to one side of the condensing device 5, and a spraying component 8 and a stirring device 9 are arranged inside the secondary distillation tower 3; The spray assembly 8 includes a manifold 81 fixed to the inner wall of the secondary distillation tower 3 through a connecting seat 12, the manifold 81 is connected to a material receiving chamber 83 through a multi-component manifold 82, the material receiving chamber 83 is connected to the negative pressure dehydration tower 1 through a feed pipe 11, and spray heads are evenly distributed around the bottom of the manifold 81, and four groups of spray heads are provided with driving components 87 for driving the spray heads to rotate; The secondary flow regulating assembly 7 includes a regulating box 78 arranged on the top of the secondary distillation tower 3, and the regulating box 78 is rotatably connected to a rotating rod 71, and the bottom of the rotating rod 71 is rotatably connected to a fixed rod 72, and the two sides of the bottom of the fixed rod 72 are fixed to the inner wall of the outlet of the secondary distillation tower 3 through support rods, and a plurality of groups of annular sleeves 73 rotatably connected to the fixed rod 72 are evenly distributed on the fixed rod 72, and regulating plates 74 are fixed on the plurality of groups of annular sleeves 73, and a gear group is arranged between the regulating plate 74 and the rotating rod 71, and the gear group is driven by a motor 10 to control the rotation of the regulating plate 74 to achieve the discharge speed of steam.

[0018] After the waste liquid raw material is added to the negative pressure dehydration tower 1 for dehydration treatment, the feed liquid is introduced into the primary distillation tower 2 and the secondary distillation tower 3 respectively. The steam after the distillation of the feed liquid in the primary distillation tower 2 enters the heat exchanger 4 under the control of the primary flow regulating component, so that the steam enters the heat exchanger 4 as a hot material. At this time, the heat exchanger 4 serves as the condenser of the primary distillation tower 2, absorbs the heat from the primary distillation tower 2, and transfers the heat to the secondary distillation tower 3 through the heat exchanger 4. The condensed liquid after condensation treatment is collected in the finished product box 6, and the steam is used for the subsequent secondary distillation. The distillation tower 3 provides heat for operation; the feed liquid enters the receiving chamber 83 in the secondary distillation tower 3, and enters the spray head through the shunt pipe 82 and the manifold 81, and the driving component 87 drives the spray head to rotate, and the spray head sprays the feed liquid evenly into the interior of the secondary distillation tower 3. At the same time, the motor 10 drives the stirring device 9 to operate. By spraying, the feed liquid to be distilled can be effectively dispersed, so that it can evaporate quickly and the distillation efficiency can be accelerated, replacing the method of directly adding the feed liquid into the distillation tower for stirring in the prior art, thereby improving the distillation efficiency of N-methylpyrrolidone; According to the needs of condensation speed, the motor 10 drives the rotating rod 71 to rotate, and cooperates with the operation of the gear set, so that the adjustment plate 74 drives the annular sleeve 73 to rotate around the fixed rod 72. There are multiple groups of adjustment plates 74. Under the cooperation of the motor 10 and the gear set, the adjustment plates 74 at the corresponding positions are driven to rotate clockwise from top to bottom, so as to open the outlet of the steam entering the adjustment box 78 in turn, so as to control the steam discharge speed by the number of rotating adjustment plates 74; the steam enters the condensation device 5 through the condensation pipe for condensation treatment, and the condensation The condensate after the reaction is collected in the finished product tank 6, and the bottom solution enters the heat exchanger 4 to be evaporated as a cold material, and refluxes to the secondary distillation tower 3 through the reflux pipe in the form of a gas-liquid mixture. At this time, the heat exchanger 4 serves as a reboiler of the secondary distillation tower 3, and transfers the heat of the primary distillation tower 2 to the secondary distillation tower 3. The feed liquid refluxed to the secondary distillation tower 3 continues to be distilled until the collection of N-methylpyrrolidone is completed. Through two parallel distillation towers, the heat exchanger 4 is used to realize heat exchange and realize multi-effect distillation, which has a good energy-saving effect.

[0019] A multiple-effect distillation method for N-methylpyrrolidone, wherein the multiple-effect distillation method is carried out using the multiple-effect distillation device, and the multiple-effect distillation method comprises the following steps: Step 1: pre-treating the waste liquid raw materials to remove impurities and non-volatile substances in the raw materials; Step 2: Open the control valve, add the pretreated liquid to the negative pressure dehydration tower 1 for dehydration treatment, and the dehydrated liquid is respectively sent to the primary distillation tower 2 and the secondary distillation tower 3 from the bottom of the negative pressure dehydration tower 1 through the feed pipe 11; Step 3: According to the requirement of steam condensation speed, the speed of steam in the primary distillation tower 2 is adjusted under the action of the primary flow regulating component, so that the steam enters the heat exchanger 4 as a hot material. At this time, the heat exchanger 4 serves as the condenser of the primary distillation tower 2, absorbs heat from the primary distillation tower 2, and transfers the heat to the secondary distillation tower 3 through the heat exchanger 4. The condensed condensate is partially collected in the finished product tank 6 under the action of the reflux pump, and partially refluxes into the primary distillation tower 2; Step 4: Start the motor 10 and the spray assembly 8, so that the feed liquid entering the secondary distillation tower 3 is sprayed inside the secondary distillation tower 3 through the spray assembly 8, and the spray liquid is heated and stirred by the stirring device 9 and the heating device; Step 5: According to the requirement of steam condensation speed, the secondary flow regulating component 7 is adjusted so that the steam enters the condensing device 5 through the condenser at the top for condensation, and is then collected in the finished product box 6 through the conduit. The solution at the bottom of the tower enters the heat exchanger 4 for evaporation as a cold material, and refluxes to the secondary distillation tower 3 through the reflux pipe in the form of a gas-liquid mixture. At this time, the heat exchanger 4 serves as a reboiler of the secondary distillation tower 3 to transfer the heat of the primary distillation tower 2 to the secondary distillation tower 3.

[0020] Embodiment 2 See attached Figure 3 and 4 In order to effectively disperse the liquid and improve the distillation efficiency, as a possible implementation mode of the present scheme, preferably, the spray head includes a spray pipe 84 rotatably connected to the manifold 81 through a rotating joint, and the bottom of the spray pipe 84 is connected to a spray chamber 85, and the bottom of the spray chamber 85 is provided with a plurality of groups of spray heads 86.

[0021] The driving component 87 includes a rotating shaft 871 arranged inside the secondary distillation tower 3, the rotating shaft 871 is rotatably connected to the material receiving chamber 83, a main gear 872 is arranged on the rotating shaft 871, and a sub-gear 873 meshing with the main gear 872 is arranged on the spray pipe 84, and a motor 10 is connected to the bottom of the rotating shaft 871.

[0022] The motor 10 rotates to drive the main gear 872 on the rotating shaft 871 to rotate, and the main gear 872 drives the sub-gear 873 meshing therewith to rotate. Since the sub-gear 873 is arranged on the spray pipe 84, the spray pipe 84, the spray chamber 85 and the nozzle 86 are driven to rotate, so that the feed liquid can be effectively and evenly dispersed in the interior of the secondary distillation tower, and the distillation effect is achieved more quickly, which speeds up the distillation efficiency of the feed liquid and ensures the distillation speed of N-methylpyrrolidone.

[0023] See attached Figure 3 and 4 In order to make the feed liquid cooperate with the effect of the spray component 8 and be effectively dispersed in the secondary distillation tower 3, as a possible implementation method of this scheme, preferably, the stirring device 9 includes a stirring frame 91 arranged inside the secondary distillation tower 3, and the stirring frame 91 is fixedly connected to the rotating shaft 871. Stirring rods 92 are evenly distributed around the top of the stirring frame 91. A stirring ring 93 is arranged on the stirring rod 92. The rotating shaft 871 is driven to rotate by the motor 10, so that the stirring frame 91 drives the stirring rod 92 and the stirring ring 93 to stir the feed liquid sprayed in the secondary distillation tower 3 that has not been distilled in time, so as to increase the distillation speed.

[0024] Embodiment 3 See attached Figure 5 and 6 In order to avoid a large amount of steam from rushing into the condenser at the same time and affecting the condensation effect, as a possible implementation method of the present scheme, preferably, several groups of the adjustment plates 74 are distributed in a stepped manner along the four sides of the fixed rod 72, and a slide groove 741 is opened on the top, and several groups of the adjustment plates 74 are provided with a slide bar 742 at the bottom, and the slide bar 742 is located on the side of the slide groove 741 of the adjacent adjustment plate 74, and the depth of the slide groove 741 is adapted to the length of the slide bar 742.

[0025] The tooth group includes a connecting rod 75 arranged on the top of the adjustment plate 74, and the connecting rod 75 is fixed to the top of the adjustment plate 74 at the stepped top. A first gear 76 is arranged on the connecting rod 75, and a second gear 77 meshing with the first gear 76 is arranged on the rotating rod 71. The rotating rod 71 is connected to the driving end of the motor 10.

[0026] The second gear 77 is driven to rotate by the motor 10. Since the first gear 76 is fixed to the connecting rod 75 and the top adjustment plate 74, the second gear 77 rotates, which can drive the first gear 76 to move around the second gear 77 in a circle. According to the condensation speed requirement of the condensing device 5, the second gear 77 cooperates with the first gear 76 to make the top adjustment plate 74 drive the bottom slide bar 742 to slide along the slide groove 741 on the top of the adjustment plate 74 adjacent to it. When the slide bar 742 moves to the inside of the slide groove 741 and is aligned with the slide groove 741, the slide bar 742 is rotated to rotate. When the inner wall is in contact, the opening for the steam to enter the regulating box 78 is increased to a size almost equivalent to that of an regulating plate 74. As the top regulating plate 74 rotates, the bottom slide bar 742 drives the regulating plates 74 adjacent to it to rotate as well, until the bottom slide bar 742 contacts the inner wall of the slide groove 741, and so on. This enables the regulating plate 74 to adjust the discharge rate of the steam in the secondary distillation tower 3 according to the needs of steam condensation, thereby avoiding a large amount of steam from quickly rushing into the condensing pipe and entering the condensing device 5, ensuring the condensation effect, and realizing the collection of the finished product.

[0027] Embodiment 4 See attached Figure 7 In order to improve the condensation efficiency of steam and ensure the effect, as a possible implementation method of this scheme, preferably, the condensing device 5 includes two groups of condensing chambers 53 fixed to the inner wall of the condensing box 52 by a holder 56, and the two groups of condensing chambers 53 are close to each other and are respectively connected to a first annular condensing tube 54 and a second annular condensing tube 55 on one side. The two groups of condensing chambers 53 are respectively connected to the refrigeration device 51 through a connecting pipe and a reflux pipe, and the first annular condensing tube 54 is arranged around the outside of the second annular condensing tube 55.

[0028] The steam enters the condensation box 52 through the condenser, and the cooling water enters the condensation chamber 53 under the action of the refrigeration device 51, and flows into the first annular condenser 54 and the second annular condenser 55 respectively, wherein the first annular condenser 54 is arranged around the outside of the second annular condenser 55, thereby increasing the contact range with the steam, being able to effectively and quickly condense the steam, achieving the recovery efficiency of the product, and ensuring the condensation effect.

[0029] The present invention is described by preferred embodiments, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. The present invention is not limited to the specific embodiments disclosed herein, and other embodiments falling within the claims of this application are within the scope of protection of the present invention.

Claims

1. A multiple-effect distillation device for N-methylpyrrolidone, characterized in that: The invention comprises a primary distillation tower (2) and a secondary distillation tower (3) connected to a negative pressure dehydration tower (1), a heat exchanger (4) being connected between the primary distillation tower (2) and the secondary distillation tower (3), a primary flow regulating component and a secondary flow regulating component (7) being respectively arranged on the top of the primary distillation tower (2) and the secondary distillation tower (3), and the primary flow regulating component and the secondary flow regulating component (7) have the same structure, a condensing device (5) being connected to one side of the secondary flow regulating component (7), the condensing device (5) being connected to a refrigeration device (51), a finished product box (6) being connected to one side of the condensing device (5), and a spraying component (8) and a stirring device (9) being arranged inside the secondary distillation tower (3); The spray assembly (8) comprises a manifold (81) fixed to the inner wall of the secondary distillation tower (3) via a connecting seat (12); the manifold (81) is connected to a material receiving chamber (83) via a multi-component manifold (82); the material receiving chamber (83) is connected to the negative pressure dehydration tower (1) via a feed pipe (11); spray heads are evenly distributed around the bottom of the manifold (81); and driving components (87) for driving the spray heads to rotate are provided on four groups of the spray heads; The secondary flow regulating assembly (7) comprises a regulating box (78) arranged on the top of the secondary distillation tower (3); a rotating rod (71) is rotatably connected to the regulating box (78); a fixed rod (72) is rotatably connected to the bottom of the rotating rod (71); two sides of the bottom of the fixed rod (72) are fixed to the inner wall of the outlet of the secondary distillation tower (3) by support rods; a plurality of groups of annular sleeves (73) rotatably connected to the fixed rod (72) are evenly spaced on the fixed rod (72); regulating plates (74) are fixed to the plurality of groups of annular sleeves (73); a gear group is arranged between the regulating plate (74) and the rotating rod (71); the gear group is driven by a motor (10) to control the rotation of the regulating plate (74) to achieve a steam discharge speed.

2. A multiple-effect distillation device for N-methylpyrrolidone according to claim 1, characterized in that: The spray head comprises a spray pipe (84) rotatably connected to the manifold (81) via a rotating joint, the bottom of the spray pipe (84) being connected to a spray chamber (85), and a plurality of groups of spray heads (86) being arranged at the bottom of the spray chamber (85).

3. A multiple-effect distillation device for N-methylpyrrolidone according to claim 2, characterized in that: The driving component (87) comprises a rotating shaft (871) arranged inside the secondary distillation tower (3); the rotating shaft (871) is rotatably connected to the bottom of the material receiving chamber (83); a main gear (872) is arranged on the rotating shaft (871); a secondary gear (873) meshing with the main gear (872) is arranged on the spray pipe (84); and a motor (10) is connected to the bottom of the rotating shaft (871).

4. A multiple-effect distillation device for N-methylpyrrolidone according to claim 1, characterized in that: Several groups of the adjustment plates (74) are evenly distributed along the periphery of the fixed rod (72) in a stepped manner, and a slide groove (741) is provided on the top of each group of the adjustment plates (74). Several groups of the adjustment plates (74) are provided with a slide rod (742) at the bottom, and the slide rod (742) is located on a side of the slide groove (741) close to the adjacent adjustment plate (74), and the depth of the slide groove (741) is adapted to the length of the slide rod (742).

5. A multiple-effect distillation device for N-methylpyrrolidone according to claim 1, characterized in that: The tooth assembly comprises a connecting rod (75) arranged at the top of the adjustment plate (74), the connecting rod (75) being fixed to the top of the adjustment plate (74) at the stepped top end, the connecting rod (75) being provided with a first gear (76), the rotating rod (71) being provided with a second gear (77) meshing with the first gear (76), and the rotating rod (71) being connected to a driving end of a motor (10).

6. A multiple-effect distillation device for N-methylpyrrolidone according to claim 1, characterized in that: The stirring device (9) comprises a stirring frame (91) arranged inside the secondary distillation tower (3), the stirring frame (91) being fixedly connected to the rotating shaft (871), stirring rods (92) being evenly distributed around the top of the stirring frame (91), and a stirring ring (93) being arranged on the stirring rods (92).

7. The multiple-effect distillation device for N-methylpyrrolidone according to claim 1, characterized in that: The condensing device (5) comprises two groups of condensing chambers (53) fixed to the inner wall of the condensing box (52) via a holder (56); the two groups of condensing chambers (53) are close to each other and are respectively connected to a first annular condensing tube (54) and a second annular condensing tube (55); the two groups of condensing chambers (53) are respectively connected to the refrigeration device (51) via a connecting pipe and a return pipe.

8. A multiple-effect distillation device for N-methylpyrrolidone according to claim 7, characterized in that: The first annular condenser tube (54) is arranged around the outside of the second annular condenser tube (55).

9. A multiple-effect distillation method for N-methylpyrrolidone, characterized in that: The multiple-effect distillation method is carried out using the multiple-effect distillation device described in any one of claims 1 to 8, and the multiple-effect distillation method comprises the following steps: Step 1: pre-treating the waste liquid raw materials to remove impurities and non-volatile substances in the raw materials; Step 2: Open the control valve and add the pretreated liquid to the negative pressure dehydration tower (1) for dehydration treatment. The dehydrated liquid is respectively sent from the bottom of the negative pressure dehydration tower (1) through the feed pipe (11) to the primary distillation tower (2) and the secondary distillation tower (3); Step 3: According to the requirement of steam condensation speed, the speed of steam in the primary distillation tower (2) is adjusted under the action of the primary flow regulating component, so that the steam enters the heat exchanger (4) as a hot material. At this time, the heat exchanger (4) serves as a condenser of the primary distillation tower (2). The condensed condensate is partially collected in the finished product tank (6) under the action of the reflux pump, and partially refluxed into the primary distillation tower (2); Step 4: starting the motor (10) and the spray assembly (8), so that the feed liquid entering the secondary distillation tower (3) is sprayed into the secondary distillation tower (3) through the spray assembly (8), and the spray liquid is heated and stirred by the stirring device (9) and the heating device; Step 5: According to the requirement of steam condensation speed, the secondary flow regulating component (7) is adjusted so that the steam enters the condensing device (5) through the condensing pipe at the top and is condensed. The steam is then collected in the finished product box (6) through the conduit. The solution at the bottom of the tower enters the heat exchanger (4) and evaporates as a cold material. The solution is then refluxed to the secondary distillation tower (3) through the reflux pipe in the form of a gas-liquid mixture. At this time, the heat exchanger (4) serves as a reboiler of the secondary distillation tower (3) and transfers the heat of the primary distillation tower (2) to the secondary distillation tower (3).

Images