A rectification device for the production and preparation of isopropyl isocyanate

Abstract

The present invention discloses a rectification device for the production and preparation of isopropyl isocyanate, which relates to the technical field of rectification. The device includes a rectification column, a tower kettle, and a fixed ring seat. A liquid collection groove is formed on the fixed ring seat. An elastic membrane is coaxially and fixedly connected to the inner hole wall of the fixed ring seat. A plurality of sieve holes are formed on the surface of the elastic membrane. When the elastic membrane is not subjected to a longitudinal force, the upper surface of the elastic membrane is flush with the upper surface of the fixed ring seat. A top membrane assembly is used to make the elastic membrane receive an upward longitudinal force, so as to cause the elastic membrane to produce an upward bulging elastic extension deformation. In the present invention, when the gas volume in the rectification column is insufficient, the top membrane assembly will trigger an action and generate an upward longitudinal force on the elastic membrane, so that the elastic membrane bulges upward, and the liquid on the upper surface of the elastic membrane will flow along the upper surface of the elastic membrane into the liquid collection groove of the fixed ring seat for collection, preventing the liquid from flowing into the lower layer of the rectification column through the sieve holes on the elastic membrane, resulting in a decrease in the gas-liquid mixing mass transfer efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of rectification, and specifically to a rectification device for the production and preparation of isopropyl isocyanate. Background Art

[0002] Rectification is a separation process that separates each component of a mixture by the different volatilities of the components. Commonly used equipment includes plate rectification towers and packed rectification towers.

[0003] The plate rectification tower is an important separation equipment widely used in the fields of chemical industry, petroleum, etc. Its working principle is based on the countercurrent contact and mass and heat transfer processes of gas-liquid two-phase. The core operation of the plate rectification tower is to utilize the countercurrent contact of gas-liquid two-phase to achieve the separation of the mixture through multiple partial vaporizations and partial condensations. The plate rectification tower is a very widely used gas-liquid mass transfer equipment, which consists of a generally cylindrical shell and a number of tower plates horizontally arranged at a certain interval therein. When the plate tower works normally, the liquid flows downward through each layer of tower plates under the action of gravity and is discharged from the tower bottom; the gas is pushed by the pressure difference, passes through the openings evenly distributed on the tower plates from bottom to top through each layer of tower plates and is discharged from the tower top. There is a certain amount of liquid stored on each tower plate. When the gas passes through the liquid layer on the plate, the two phases contact for mass transfer.

[0004] In the process of rectifying isopropyl isocyanate with the existing plate rectification tower, a liquid leakage phenomenon usually occurs, that is, due to insufficient gas volume of the steam, the liquid on the tower plate leaks through the sieve holes of the tower plate, thereby affecting the gas-liquid mixing mass transfer efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a rectification device for the production and preparation of isopropyl isocyanate to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A rectification device for the production and preparation of isopropyl isocyanate, including a rectification tower with a gas phase outlet, a liquid phase reflux port at the upper end and a gas phase inlet at the lower end. The end of the gas phase inlet is connected to a tower kettle through penetration, and further includes:

[0008] A plurality of fixed ring seats horizontally and fixedly connected to the inner wall of the rectification tower in sequence from top to bottom. An annular liquid collection groove is coaxially opened on the upper end surface of the fixed ring seat;

[0009] An elastic membrane coaxially fixedly connected to the inner wall of the middle hole of the fixed ring seat. A plurality of sieve holes are opened on the surface of the elastic membrane, and when the elastic membrane is not subjected to a longitudinal force, the upper surface of the elastic membrane is flush with the upper surface of the fixed ring seat;

[0010] The top membrane assembly disposed within the rectification column, the top membrane assembly being configured to apply an upward longitudinal force to the elastic membrane, thereby causing the elastic membrane to undergo an elastic extension deformation with an upward bulge.

[0011] Through the above technical solution, when the gas volume within the rectification column is insufficient, the top membrane assembly will trigger an action and apply an upward longitudinal force to the elastic membrane, thereby causing the elastic membrane to bulge upward. As a result, the liquid on the upper surface of the elastic membrane will flow along the upper surface of the elastic membrane to the liquid collection groove of the fixed ring seat for collection, preventing the liquid from flowing into the lower layer of the rectification column through the sieve holes on the elastic membrane and causing a decrease in the gas-liquid mass transfer efficiency.

[0012] Furthermore, a stirrer is provided at the bottom of the tower kettle.

[0013] Through the above technical solution, the stirrer stirs the isopropyl isocyanate mixture within the tower kettle, thereby making the mixture receive more uniform heating and accelerating steam evaporation.

[0014] Furthermore, a liquid pressing assembly is provided on the fixed ring seat. The liquid pressing assembly includes a plurality of guide columns vertically fixed to the upper surface of the fixed ring seat. Above the fixed ring seat, there is a floating ring. The floating ring is provided with guide holes for the free passage of the guide columns. The lower surface of the floating ring is fixedly connected with a plurality of vertical pipes. The lower ends of the plurality of vertical pipes are commonly fixedly connected with a liquid pressing ring plate. When the liquid pressing ring plate moves downward, it will be inserted into the liquid collection groove and is in sliding fit with the inner wall of the liquid collection groove. The surface of the floating ring is fixedly connected with a floating bracket, and the floating bracket abuts against the upper surface of the elastic membrane. The liquid pressing ring plate is provided with a liquid outlet structure.

[0015] Through the above technical solution, when the floating ring moves downward, the liquid pressing ring plate is inserted into the liquid collection groove, and the liquid in the liquid collection groove is squeezed to the liquid outlet structure. At the same time, the liquid is sprayed onto the upper surface of the elastic membrane by the liquid outlet structure. Thus, when the gas volume is sufficient, the liquid in the liquid collection groove can be remixed for mass transfer.

[0016] Furthermore, the liquid outlet structure includes a spray pipe fixedly connected to the outer wall of the vertical pipe in a penetrating manner. The end of the spray pipe away from the vertical pipe extends toward the center side of the elastic membrane. The inside of the liquid pressing ring plate is hollow and its bottom surface is provided with a plurality of liquid inlet holes, and the liquid inlet holes are in communication with the inner cavity of the liquid pressing ring plate and the vertical pipe.

[0017] Through the above technical solution, after the liquid pressing ring plate is inserted into the liquid collection groove, it will squeeze the liquid in the liquid collection groove, causing the liquid to enter the vertical pipe through the liquid inlet holes and be sprayed out by the spray pipe. Thus, the liquid in the liquid collection groove can be sprayed onto the surface of the elastic membrane to facilitate re-gas-liquid mass transfer.

[0018] Further, a stop ring is fixedly sleeved on the upper end of the guide post, a return spring is wound around the periphery of the guide post, and two ends in the elastic force direction of the return spring elastically abut against the bottom surface of the stop ring and the top surface of the floating ring respectively.

[0019] Through the above technical solution, a downward elastic abutting force is generated on the floating ring by the return spring, so that the pressure of the liquid pressing ring plate on the liquid in the liquid collecting tank is relatively large, enabling the liquid to be ejected from the nozzle quickly and fully.

[0020] Further, the top film assembly includes an upper air collecting hood fixedly connected to the inner wall of the rectifying column and abutting against the bottom surface of the fixed ring seat. A communication chamber is connected through the bottom of the upper air collecting hood. A lower air collecting hood is fixedly connected to the lower end of the communication chamber. A sealing portion is coaxially fixedly connected to the inner cavity wall of the communication chamber. A plurality of air inlet holes are formed in the end surface of the sealing portion. A top film rod is slidably inserted through the sealing portion. The top film rod is used in cooperation with the elastic film. An air jacking structure is further provided on the sealing portion, and the air jacking structure is used to drive the top film rod to move up and down.

[0021] Through the above technical solution, the arrangement of the lower air collecting hood and the upper air collecting hood enables the steam in the rectifying column to trigger the action of the air jacking structure through the guiding action of the lower air collecting hood, and trigger the action of the top film rod through the air jacking structure.

[0022] Further, the air jacking structure includes a sliding rod vertically slidably inserted through the sealing portion. A counterweight plate is fixedly connected to the upper end of the sliding rod. A sealing plunger used in cooperation with the air inlet hole is fixedly connected to the bottom surface of the counterweight plate. The top film rod and the sliding rod are connected through a transmission unit, so that when the sliding rod moves vertically, it drives the top film rod to move synchronously in the opposite direction.

[0023] Through the above technical solution, the steam in the rectifying column generates an upward jacking force on the sealing plunger, so that the sealing plunger can slide upward in the air inlet hole and the air inlet hole is opened. When the steam volume in the rectifying column is small and the air pressure is small, the upward movement stroke of the sealing plunger is reduced, so that the transmission unit can be triggered to act and drive the top film rod to move upward, causing the top film rod to abut against the elastic film and making the elastic film bulge upward.

[0024] Further, the aperture of the air inlet hole decreases successively from top to bottom.

[0025] Through the above technical solution, this makes the resistance of the sealing plunger sliding in the air inlet hole smaller.

[0026] Furthermore, the transmission unit includes a support arm fixed to the bottom surface of the sealing part, and a transmission gear is rotatably connected to the support arm. A first rack segment that meshes with the outside of the transmission gear is provided at the periphery of the top membrane rod, and a second rack segment that meshes with the outside of the transmission gear is provided at the periphery of the sliding rod. The first rack segment and the second rack segment are respectively located on both sides of the radial direction of the transmission gear.

[0027] Through the above technical solution, when the sealing plunger moves and drives the counterweight plate to move, the sliding rod will move synchronously, and then the second rack segment and the transmission gear will engage and transmit, and the transmission gear will engage and transmit with the first rack segment, thereby driving the top membrane rod to move in the opposite direction synchronously, so that when the air volume is insufficient, the top membrane rod moves upward, causing the elastic membrane to bulge, and when the air volume is sufficient, the top membrane rod moves downward, causing the upper surface of the elastic membrane to tend to be flat.

[0028] Furthermore, the outer diameter of the sealing plunger is smaller than the aperture of the air inlet hole.

[0029] Through the above technical solution, when the gas volume in the distillation tower is low, steam can still overflow from the air inlet, avoiding the situation where the gas pressure is insufficient to drive the sealing plunger to move when the gas volume is low, thereby causing steam to accumulate in the lower layer of the distillation tower.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. In the present invention, when the gas volume in the distillation tower is insufficient, the top membrane assembly will be triggered to generate an upward longitudinal force on the elastic membrane, thereby causing the elastic membrane to bulge upward, so that the liquid on the upper surface of the elastic membrane will flow along the upper surface of the elastic membrane to the liquid collecting trough of the fixed ring seat for collection, thereby preventing the liquid from flowing into the lower layer of the distillation tower through the sieve holes on the elastic membrane, resulting in a decrease in the gas-liquid mixing mass transfer efficiency;

[0032] 2. In the present invention, after the liquid pressure ring plate is inserted into the liquid collecting tank, it squeezes the liquid in the liquid collecting tank, causing the liquid to enter the riser through the liquid inlet hole and be sprayed out through the nozzle. The liquid in the liquid collecting tank can then be sprayed onto the surface of the elastic membrane, thereby facilitating gas-liquid mixing and mass transfer.

[0033] 3. In the present invention, when the sealing plunger moves and drives the counterweight plate to move, the sliding rod will move synchronously, and then the second rack segment and the transmission gear will engage and transmit, and the transmission gear will engage and transmit with the first rack segment, thereby driving the top membrane rod to move in the opposite direction synchronously, so that when the air volume is insufficient, the top membrane rod moves upward, causing the elastic membrane to bulge, and when the air volume is sufficient, the top membrane rod moves downward, causing the upper surface of the elastic membrane to tend to be flat. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1This is a schematic diagram of the overall structure of a distillation device for producing isopropyl isocyanate in the present invention;

[0035] Figure 2 This is a schematic diagram of the positional relationship of the distillation tower after the tower kettle is omitted in the present invention;

[0036] Figure 3 for Figure 2 A schematic diagram of the positional relationship from another perspective;

[0037] Figure 4 Schematic diagram of the positional relationship between the upper gas collecting hood, the lower gas collecting hood and the fixed ring seat after assembly in the present invention;

[0038] Figure 5 for Figure 4 A schematic diagram of the positional relationship from another perspective;

[0039] Figure 6 for Figure 5 Schematic diagram of the positional relationship of the middle part structure after it is cut open;

[0040] Figure 7 for Figure 6 A magnified schematic diagram of the local structure at point A;

[0041] Figure 8 Schematic diagram of the positional relationship among the sealing portion, the counterweight plate and the top membrane rod after assembly in the present invention;

[0042] Figure 9 for Figure 8 Schematic diagram of the positional relationship of the middle part structure after it is cut open;

[0043] Figure 10 Schematic diagram of the positional relationship among the hydraulic ring plate, floating ring and floating frame after assembly in the present invention;

[0044] Figure 11 for Figure 10 Schematic diagram of the positional relationship of the middle part structure after it is cut open;

[0045] Figure 12 for Figure 10 Schematic diagram of the positional relationship from another perspective.

[0046] In the figure, the descriptions of each reference numeral are as follows: 1. agitator; 2. bottom kettle; 3. gas-phase inlet; 4. distillation column; 5. liquid-phase reflux port; 6. gas-phase outlet; 7. lower gas-gathering hood; 8. fixed ring seat; 9. floating ring; 10. elastic membrane; 11. communication chamber; 12. upper gas-gathering hood; 13. floating frame; 14. spray pipe; 15. riser pipe; 16. liquid-pressing ring plate; 17. top membrane rod; 18. sealing part; 19. stop ring; 20. return spring; 21. guide post; 22. liquid-collecting tank; 23. liquid inlet hole; 24. first rack segment; 25. transmission gear; 26. sliding rod; 27. counterweight plate; 28. sealing plunger; 29. air inlet hole; 30. second rack segment. Detailed implementation manners

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] Please refer to Figures 1-12 , the present invention provides a technical solution: a distillation device for the production and preparation of isopropyl isocyanate, including a distillation column 4 with a gas-phase outlet 6 and a liquid-phase reflux port 5 at the upper end and a gas-phase inlet 3 at the lower end. The end of the gas-phase inlet 3 is connected to a bottom kettle 2 through a through connection. The bottom kettle 2 is installed on an external support, so that the bottom kettle 2 is suspended above the ground. At the same time, the distillation column 4 is installed above the bottom kettle 2. The gas-phase outlet 6 is connected to the inlet of an external condenser through a pipeline, and the liquid-phase reflux port 5 is connected to the liquid outlet of the condenser through a pipeline. In this way, the liquid can flow back to the liquid-phase reflux port 5 and then enter the distillation column 4. The isopropyl isocyanate raw material is heated in the bottom kettle 2 to form steam, and the steam enters the distillation column 4 through the gas-phase inlet 3. In addition, a stirrer 1 is installed at the bottom of the bottom kettle 2, and the stirrer 1 is used to stir the raw materials in the bottom kettle 2, so that the raw materials are heated more evenly;

[0049] A plurality of fixed ring seats 8 are horizontally and fixedly connected to the inner wall of the distillation column 4 in sequence from top to bottom. The upper end surface of the fixed ring seat 8 is coaxially provided with an annular liquid-collecting tank 22 (as shown in Figure 7 ), and a circular elastic membrane 10 is fixedly connected to the middle hole wall of the fixed ring seat 8 by physical or chemical means. The elastic membrane 10 is made of rubber material and has good elastic extensibility and deformation ability. The elastic membrane 10 is coaxial with the fixed ring seat 8. In addition, a plurality of sieve holes are provided on the surface of the elastic membrane 10, and both liquid and gas can pass through the sieve holes. In addition, when the elastic membrane 10 is not subjected to a longitudinal force, the upper surface of the elastic membrane 10 is flush with the upper surface of the fixed ring seat 8;

[0050] On the upper surface of the fixed ring seat 8, four guide posts 21 are vertically fixed. The four guide posts 21 are arranged in an axial array along the fixed ring seat 8. In addition, a floating ring 9 is provided above the fixed ring seat 8. A guide hole for the free passage of the guide posts 21 is provided on the floating ring 9. A plurality of riser pipes 15 are fixed to the lower surface of the floating ring 9. The lower ends of the plurality of riser pipes 15 are jointly fixed with a liquid pressing ring plate 16 (as Figure 12 shown). When the liquid pressing ring plate 16 moves downward, it will be stuck into the liquid collecting groove 22 and is in sliding fit with the inner wall of the liquid collecting groove 22. A floating frame 13 is fixed to the surface of the floating ring 9. The floating frame 13 abuts against the upper surface of the elastic membrane 10. A spray pipe 14 is fixed to the outer wall of the riser pipe 15. The inside of the spray pipe 14 is in through connection with the inside of the riser pipe 15. In addition, the spray pipe 14 is arranged horizontally, and the end of the spray pipe 14 away from the riser pipe 15 extends toward the center side of the elastic membrane 10. The inside of the liquid pressing ring plate 16 is hollow and a plurality of liquid inlet holes 23 are provided on the bottom surface. The liquid inlet holes 23 are in through connection with the inner cavity of the liquid pressing ring plate 16 and the riser pipe 15. A stop ring 19 is fixedly sleeved on the upper end of the guide post 21. A return spring 20 is wound around the periphery of the guide post 21. The two ends of the return spring 20 in the direction of the elastic force are elastically abutted against the bottom surface of the stop ring 19 and the top surface of the floating ring 9 respectively. When the floating ring 9 moves upward, the return spring 20 will be squeezed by the top surface of the floating ring 9, and then be compressed and store elastic potential energy;

[0051] An upper gas collecting hood 12 is fixed to the inner wall of the rectification column 4. The upper gas collecting hood 12 abuts against the bottom surface of the fixed ring seat 8. A communication chamber 11 is connected through the bottom of the upper gas collecting hood 12. A lower gas collecting hood 7 is fixed to the lower end of the communication chamber 11. A sealing part 18 is coaxially fixed to the inner cavity wall of the communication chamber 11. A plurality of air inlet holes 29 are provided on the end face of the sealing part 18. A top film rod 17 is slidably penetrated through the sealing part 18. The top film rod 17 is used in cooperation with the elastic membrane 10, that is, the top film rod 17 is located directly below the elastic membrane 10. A sliding rod 26 is vertically slidably penetrated through the sealing part 18. A counterweight plate 27 is fixed to the upper end of the sliding rod 26. A sealing plunger 28 for cooperating with the air inlet hole 29 is fixed to the bottom surface of the counterweight plate 27. The aperture of the air inlet hole 29 decreases sequentially from top to bottom, and the outer diameter of the sealing plunger 28 is smaller than the aperture of the air inlet hole 29. A support arm is fixed to the bottom surface of the sealing part 18. A transmission gear 25 is rotatably connected to the support arm. A first rack section 24 meshing with the outer part of the transmission gear 25 is provided on the periphery of the top film rod 17. A second rack section 30 meshing with the outer part of the transmission gear 25 is provided on the periphery of the sliding rod 26. The first rack section 24 and the second rack section 30 are respectively located on both sides of the radial direction of the transmission gear 25. In this way, when the transmission gear 25 rotates, the moving directions of the first rack section 24 and the second rack section 30 are opposite.

[0052] The working principle of the present invention:

[0053] The steam in the distillation tower 4 has a lifting force on the sealing plunger 28, causing the sealing plunger 28 to move upward, so that the sealing plunger 28 drives the counterweight plate 27 to move upward. When the counterweight plate 27 moves upward, it will cause the sliding rod 26 to move upward. When the sliding rod 26 moves upward, the second rack segment 30 and the transmission gear 25 are meshed and transmitted. The transmission gear 25 is also meshed and transmitted with the first rack segment 24, so that the movement directions of the second rack segment 30 and the first rack segment 24 are opposite. Under normal circumstances, the steam in the distillation tower 4 drives the sealing plunger 28 to move upward within a certain range, so that the membrane top rod 17 does not lift the elastic membrane 10.

[0054] When the gas volume in the distillation tower 4 is insufficient, the upward movement stroke of the sealing plunger 28 is small. At this time, the gravity of the counterweight plate 27 will cause the sealing plunger 28 to move downward (or the movement stroke of the sealing plunger 28 is reduced compared to the normal situation). This will cause the transmission gear 25 to rotate in the opposite direction, thereby causing the top membrane rod 17 to move upward and lift the elastic membrane 10, thereby causing the upper surface of the elastic membrane 10 to bulge. When the elastic membrane 10 bulges, it generates a lifting force on the floating frame 13. The floating frame 13 will drive the floating ring 9 to move upward, causing the pressure liquid ring plate 16 to move upward and disengage from the engaging state with the liquid collecting tank 22. At this time, the liquid on the upper surface of the elastic membrane 10 will flow into the liquid collecting tank 22 along the upper surface of the elastic membrane 10 for collection. When the floating ring 9 moves upward, it will compress the return spring 20, causing the return spring 20 to accumulate elastic potential energy.

[0055] When the gas volume in the distillation tower 4 is sufficient, the upward movement stroke of the sealing plunger 28 increases, thereby causing the top membrane rod 17 to move downward, and the elastic membrane 10 recovers its deformation, so that the upper surface of the elastic membrane 10 is flush with the upper surface of the fixed ring seat 8. At the same time, the reset spring 20 drives the floating ring 9 to move downward, so that the pressure liquid ring plate 16 is stuck in the liquid collecting tank 22. The liquid in the liquid collecting tank 22 will enter the riser 15 through the liquid inlet hole 23, and then be sprayed onto the surface of the elastic membrane 10 from the nozzle 14. The steam passes through the sieve holes to transfer and mix the liquid on the surface of the elastic membrane 10.

[0056] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A distillation device for producing isopropyl isocyanate, comprising a distillation tower (4) having a gas phase outlet (6) and a liquid phase reflux port (5) at its upper end and a gas phase inlet (3) at its lower end, wherein the gas phase inlet (3) is connected to a tower reactor (2) at its end, characterized in that: Also includes: A plurality of fixed ring seats (8) are fixedly connected horizontally to the inner wall of the distillation tower (4) in sequence from top to bottom, and an annular liquid collecting trough (22) is coaxially formed on the upper end surface of the fixed ring seat (8); An elastic membrane (10) is coaxially fixed to the hole wall of the fixed ring seat (8), a plurality of sieve holes are provided on the surface of the elastic membrane (10), and when the elastic membrane (10) is not subjected to a longitudinal force, the upper surface of the elastic membrane (10) is flush with the upper surface of the fixed ring seat (8); A top membrane assembly is provided in the distillation tower (4), the top membrane assembly being used to subject the elastic membrane (10) to an upward longitudinal force, thereby causing the elastic membrane (10) to undergo an elastic extension deformation such that it bulges upward; The top membrane assembly includes an upper gas collecting hood (12) fixed to the inner wall of the distillation tower (4) and abutting against the bottom surface of the fixed ring seat (8), the bottom of the upper gas collecting hood (12) is connected with a connecting chamber (11), the lower end of the connecting chamber (11) is fixed with a lower gas collecting hood (7), the inner cavity wall of the connecting chamber (11) is coaxially fixed with a sealing portion (18), the end surface of the sealing portion (18) is provided with a plurality of air inlet holes (29), a top membrane rod (17) is slidably penetrated on the sealing portion (18), the top membrane rod (17) is used in conjunction with the elastic membrane (10), and a gas cap structure is also provided on the sealing portion (18), the gas cap structure is used to drive the top membrane rod (17) to move up and down; The air top structure includes a sliding rod (26) vertically slidingly penetrated on the sealing portion (18), the upper end of the sliding rod (26) is fixedly connected to a counterweight plate (27), the bottom surface of the counterweight plate (27) is fixedly connected to a sealing plunger (28) used in conjunction with the air inlet hole (29), and the top film rod (17) and the sliding rod (26) are connected by a transmission unit, so that when the sliding rod (26) moves vertically, it drives the top film rod (17) to move synchronously in the opposite direction.

2. A distillation device for producing isopropyl isocyanate according to claim 1, characterized in that: A stirrer (1) is provided at the bottom of the tower kettle (2).

3. A distillation device for producing isopropyl isocyanate according to claim 1, characterized in that: The fixed ring seat (8) is provided with a pressure liquid component, and the pressure liquid component includes a plurality of guide columns (21) vertically fixed to the upper surface of the fixed ring seat (8); a floating ring (9) is provided above the fixed ring seat (8); a guide hole for the guide column (21) to pass freely is opened on the floating ring (9); a plurality of vertical pipes (15) are fixed to the lower surface of the floating ring (9); the lower ends of the plurality of vertical pipes (15) are commonly fixed to a pressure liquid ring plate (16); when the pressure liquid ring plate (16) moves downward, it will be stuck in the liquid collecting tank (22) and be in sliding fit with the inner wall of the liquid collecting tank (22); a floating frame (13) is fixed to the surface of the floating ring (9); the floating frame (13) is in contact with the upper surface of the elastic membrane (10); and a liquid outlet structure is provided on the pressure liquid ring plate (16).

4. A distillation device for producing isopropyl isocyanate according to claim 3, characterized in that: The liquid outlet structure includes a nozzle (14) fixedly connected to the outer wall of the vertical pipe (15). One end of the nozzle (14) away from the vertical pipe (15) extends toward the center side of the elastic membrane (10). The pressure liquid ring plate (16) is hollow inside and has a plurality of liquid inlet holes (23) on the bottom surface. The liquid inlet holes (23) are connected to the inner cavity of the pressure liquid ring plate (16) and the vertical pipe (15).

5. The distillation device for producing isopropyl isocyanate according to claim 3, characterized in that: The upper end of the guide column (21) is fixedly sleeved with a stop ring (19), and the periphery of the guide column (21) is sleeved with a return spring (20), and the two ends of the return spring (20) in the elastic direction elastically press against the bottom surface of the stop ring (19) and the top surface of the floating ring (9) respectively.

6. The distillation device for producing isopropyl isocyanate according to claim 1, characterized in that: The apertures of the air inlet holes (29) decrease from top to bottom.

7. The distillation device for producing isopropyl isocyanate according to claim 1, characterized in that: The transmission unit includes a support arm fixed to the bottom surface of the sealing portion (18), and a transmission gear (25) is rotatably connected to the support arm. A first rack segment (24) is provided on the periphery of the top membrane rod (17) and is meshed with the outside of the transmission gear (25). A second rack segment (30) is provided on the periphery of the sliding rod (26) and is meshed with the outside of the transmission gear (25). The first rack segment (24) and the second rack segment (30) are respectively located on both sides of the radial direction of the transmission gear (25).

8. The distillation device for producing isopropyl isocyanate according to claim 1, characterized in that: The outer diameter of the sealing plunger (28) is smaller than the aperture of the air inlet hole (29).

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