Rectification device for isopropyl isocyanate production and preparation

Abstract

The invention discloses a rectification device for isopropyl isocyanate production and preparation, and relates to the technical field of rectification, the rectification device comprises a rectification tower, a tower kettle and a fixed ring seat, and the fixed ring seat is provided with a liquid collecting groove; the elastic film is coaxially and fixedly connected to the hole wall in the fixing ring seat, a plurality of sieve holes are formed in the surface of the elastic film, and when the elastic film is not subjected to longitudinal acting force, the upper surface of the elastic film is flush with the upper surface of the fixing ring seat; and the top film assembly is used for enabling the elastic film to be subjected to upward longitudinal acting force, so that the elastic film generates upward raised elastic extension deformation. According to the invention, when the air quantity in the rectifying tower is insufficient, the top film assembly triggers the action and generates upward longitudinal acting force on the elastic film, so that the elastic film bulges upwards, and liquid on the upper surface of the elastic film flows into the liquid collecting groove of the fixed ring seat along the upper surface of the elastic film to be collected; the liquid is prevented from flowing into the lower layer of the rectifying tower from the sieve pores in the elastic film to reduce 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 based on 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 device widely used in the fields of chemical engineering, 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 use 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 widely used gas-liquid mass transfer device, which consists of a generally cylindrical shell and a number of trays horizontally arranged at a certain interval therein. When the plate tower works normally, the liquid flows downwards through each tray under the action of gravity and is discharged from the bottom of the tower; the gas is pushed by the pressure difference, passes through the openings evenly distributed on the tray from bottom to top through each tray, and is discharged from the top of the tower. A certain amount of liquid is stored on each tray. When the gas passes through the liquid layer on the tray, the two phases contact for mass transfer.

[0004] During the rectification operation of 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 tray leaks from the sieve holes of the tray, 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: 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 reboiler in a through manner, and further includes: A plurality of fixed ring seats horizontally and fixedly connected to the inner wall of the rectification tower from top to bottom in sequence. The upper end surface of the fixed ring seat is coaxially provided with an annular liquid collection groove; An elastic membrane coaxially fixedly connected to the inner wall of the middle hole of the fixed ring seat. The surface of the elastic membrane is provided with a plurality of sieve holes, 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; A top membrane assembly arranged in the rectification tower, and the top membrane assembly is used to make the elastic membrane receive an upward longitudinal force, so that the elastic membrane generates an upward bulging elastic extension deformation.

[0007] With the above technical solution, 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, 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 into the liquid collection tank 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 resulting in a decrease in the gas-liquid mixed mass transfer efficiency.

[0008] Furthermore, a stirrer is provided at the bottom of the tower kettle.

[0009] With the above technical solution, the stirrer stirs the isopropyl isocyanate mixture in the tower kettle, so that the mixture is heated more evenly, thereby accelerating the evaporation of steam.

[0010] Furthermore, a liquid pressing assembly is provided on the fixed ring seat. The liquid pressing assembly includes a plurality of guide columns vertically fixed on the upper surface of the fixed ring seat. A floating ring is provided above the fixed ring seat. The floating ring is provided with guide holes for the free passage of the guide columns. A plurality of vertical pipes are fixedly connected to the lower surface of the floating ring. 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 stuck into the liquid collection tank and is in sliding fit with the inner wall of the liquid collection tank. A floating frame is fixedly connected to the surface of the floating ring. The floating frame abuts against the upper surface of the elastic membrane. An out-liquid structure is provided on the liquid pressing ring plate.

[0011] With the above technical solution, when the floating ring moves downward, the liquid pressing ring plate is stuck into the liquid collection tank, and the liquid in the liquid collection tank is squeezed to the out-liquid structure. At the same time, it is sprayed onto the upper surface of the elastic membrane by the out-liquid structure, so that when the gas volume is sufficient, the liquid in the liquid collection tank can be remixed for mass transfer.

[0012] Furthermore, the out-liquid 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 a plurality of liquid inlet holes are provided on the bottom surface. The liquid inlet holes are communicated with the inner cavity of the liquid pressing ring plate and the vertical pipe.

[0013] With the above technical solution, after the liquid pressing ring plate is stuck into the liquid collection tank, it will squeeze the liquid in the liquid collection tank, so that the liquid enters the vertical pipe through the liquid inlet holes and is sprayed out by the spray pipe, so that the liquid in the liquid collection tank can be sprayed onto the surface of the elastic membrane to facilitate the re-mixing of gas and liquid for mass transfer.

[0014] Furthermore, a stop ring is fixedly sleeved on the upper end of the guide column. A return spring is wound around the periphery of the guide column. The two ends of 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.

[0015] Through the above technical solution, the reset spring generates a downward elastic abutting force on the floating ring, 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.

[0016] Furthermore, 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 on 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.

[0017] 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.

[0018] Furthermore, the air jacking structure includes a sliding rod slidably inserted through the sealing portion vertically. 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.

[0019] 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 low, 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, making the top film rod abut against the elastic film and causing the elastic film to bulge upward.

[0020] Furthermore, the aperture of the air inlet hole decreases sequentially from top to bottom.

[0021] Through the above technical solution, this makes the resistance of the sealing plunger sliding in the air inlet hole smaller.

[0022] Furthermore, the transmission unit includes a support arm fixedly connected to the bottom surface of the sealing portion. A transmission gear is rotatably connected to the support arm. A first rack segment meshing with the outer part of the transmission gear is formed on the periphery of the top film rod. A second rack segment meshing with the outer part of the transmission gear is formed on 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.

[0023] Through the above technical scheme, 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.

[0024] Furthermore, the outer diameter of the sealing plunger is smaller than the aperture of the air inlet hole.

[0025] Through the above technical solution, when the gas volume in the distillation tower is low, steam can still overflow from the air inlet hole, 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.

[0026] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, when the gas volume in the distillation tower is insufficient, the top membrane assembly will be triggered to act and 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 tank 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; 2. In the present invention, after the liquid pressure ring plate is inserted into the liquid collecting tank, it will squeeze the liquid in the liquid collecting tank, so that the liquid enters the vertical pipe from the liquid inlet hole and is sprayed out from the nozzle, and then the liquid in the liquid collecting tank can be sprayed onto the surface of the elastic membrane, so as to facilitate gas-liquid mixing and mass transfer again; 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 gas volume is insufficient, the top membrane rod moves upward, causing the elastic membrane to bulge, and when the gas 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

[0027] Figure 1 This is a schematic diagram of the overall structure of a distillation device for producing and preparing isopropyl isocyanate in the present invention; Figure 2 It is a schematic diagram of the positional relationship of the distillation tower after the tower kettle is omitted and the distillation tower is cut open; Figure 3 for Figure 2 A schematic diagram of the positional relationship from another perspective; Figure 4 It is a schematic diagram of the positional relationship of the upper gas collecting hood, the lower gas collecting hood and the fixed ring seat after being assembled in the present invention; Figure 5 is Figure 4 a schematic diagram of the positional relationship from another perspective in Figure 6 is Figure 5 a schematic diagram of the positional relationship after a part of the structure in is cut open; Figure 7 is Figure 6 an enlarged schematic diagram of the local structure at position A in Figure 8 is a schematic diagram of the positional relationship after the sealing part, the counterweight plate and the top film rod in the present invention are assembled; Figure 9 is Figure 8 a schematic diagram of the positional relationship after a part of the structure in is cut open; Figure 10 is a schematic diagram of the positional relationship after the liquid pressure ring plate, the floating ring and the floating frame in the present invention are assembled; Figure 11 is Figure 10 a schematic diagram of the positional relationship after a part of the structure in is cut open; Figure 12 is Figure 10 a schematic diagram of the positional relationship from another perspective in .

[0028] In the figures, the descriptions of the reference numerals are as follows: 1, stirrer; 2, tower kettle; 3, gas phase inlet; 4, rectifying 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 pressure ring plate; 17, top film rod; 18, sealing part; 19, stop ring; 20, return spring; 21, guide post; 22, liquid collection 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. Specific Embodiments

[0029] 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.

[0030] Please refer to Figures 1-12, the present invention provides a technical solution: a rectification device for the production and preparation of isopropyl isocyanate, including a rectification tower 4 with a gas phase outlet 6, 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 through to a tower kettle 2. The tower kettle 2 is installed on an external support, so that the tower kettle 2 is suspended above the ground. At the same time, the rectification tower 4 is installed above the tower 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, so that the liquid can flow back to the liquid phase reflux port 5 and then enter the rectification tower 4 again. The isopropyl isocyanate raw material is heated in the tower kettle 2 to form steam, and the steam enters the rectification tower 4 through the gas phase inlet 3. In addition, a stirrer 1 is installed at the bottom of the tower kettle 2, and the stirrer 1 is used to stir the raw materials in the tower kettle 2, so that the raw materials are heated more evenly; A plurality of fixed ring seats 8 are horizontally and fixedly connected to the inner wall of the rectification tower 4 from top to bottom in sequence. The upper end surface of the fixed ring seat 8 is coaxially provided with an annular liquid collecting groove 22 (as Figure 7 shown), 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 extension 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; Four guide columns 21 are vertically and fixedly connected to the upper surface of the fixed ring seat 8. The four guide columns 21 are arranged in an array along the axial direction of 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 column 21 is provided on the floating ring 9. A plurality of vertical pipes 15 are fixedly connected to the lower surface of the floating ring 9. The lower ends of the plurality of vertical pipes 15 are commonly fixedly connected to 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 fixedly connected to the surface of the floating ring 9, and the floating frame 13 abuts against the upper surface of the elastic membrane 10. A spray pipe 14 is fixedly connected to the outer wall of the vertical pipe 15. The inside of the spray pipe 14 is in through connection with the inside of the vertical pipe 15. In addition, the spray pipe 14 is horizontally arranged, and the end of the spray pipe 14 away from the vertical 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 vertical pipe 15. A stop ring 19 is fixedly sleeved on the upper end of the guide column 21, and a return spring 20 is wound around the periphery of the guide column 21. The two ends of the elastic force direction of the return spring 20 are respectively elastically abutted against the bottom surface of the stop ring 19 and the top surface of the floating ring 9. 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 accumulate elastic potential energy; An upper gas hood 12 is fixedly connected to the inner wall of the rectifying column 4. The upper gas hood 12 abuts against the bottom surface of the fixed ring seat 8. A communicating chamber 11 is connected through the bottom of the upper gas hood 12. A lower gas hood 7 is fixedly connected to the lower end of the communicating chamber 11. A sealing portion 18 is coaxially and fixedly connected to the inner cavity wall of the communicating chamber 11. A plurality of air inlet holes 29 are formed in the end face of the sealing portion 18. A top film rod 17 is slidably inserted through the sealing portion 18. The top film rod 17 is used in cooperation with the elastic film 10, that is, the top film rod 17 is located directly below the elastic film 10. A sliding rod 26 is vertically and slidably inserted through the sealing portion 18. A weight plate 27 is fixedly connected to the upper end of the sliding rod 26. A sealing plunger 28 used in cooperation with the air inlet hole 29 is fixedly connected to the bottom surface of the weight plate 27. The aperture of the air inlet hole 29 gradually decreases 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 fixedly connected to the bottom surface of the sealing portion 18. A transmission gear 25 is rotatably connected to the support arm. A first rack segment 24 meshing with the outer teeth of the transmission gear 25 is formed on the periphery of the top film rod 17. A second rack segment 30 meshing with the outer teeth of the transmission gear 25 is formed on the periphery of the sliding rod 26. The first rack segment 24 and the second rack segment 30 are respectively located on both radial sides of the transmission gear 25. In this way, when the transmission gear 25 rotates, the moving directions of the first rack segment 24 and the second rack segment 30 are opposite.

[0031] The working principle of the present invention: The steam in the rectifying column 4 has a jacking force on the sealing plunger 28, causing the sealing plunger 28 to move upward, and the sealing plunger 28 drives the weight plate 27 to move upward. When the weight 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 engaged for transmission, and the transmission gear 25 is also engaged with the first rack segment 24 for transmission. As a result, the moving directions of the second rack segment 30 and the first rack segment 24 are opposite. Under normal circumstances, the upward movement stroke of the sealing plunger 28 driven by the steam in the rectifying column 4 is within a certain range, so that the top film rod 17 does not lift the elastic film 10. When the gas volume in the rectifying column 4 is insufficient, the upward movement stroke of the sealing plunger 28 is small. At this time, the gravity of the weight plate 27 will cause the sealing plunger 28 to move downward (or the moving stroke of the sealing plunger 28 is reduced compared to the normal situation), so that the transmission gear 25 rotates in the reverse direction, and then the top film rod 17 moves upward and lifts the elastic film 10, so that the upper surface of the elastic film 10 bulges. When the elastic film 10 bulges, it generates a jacking force on the floating frame 13, and the floating frame 13 drives the floating ring 9 to move upward, causing the pressure liquid ring plate 16 to move upward and disengage from the clamping state with the liquid collecting groove 22. At this time, the liquid on the upper surface of the elastic film 10 will flow along the upper surface of the elastic film 10 into the liquid collecting groove 22 for collection. When the floating ring 9 moves upward, it compresses the return spring 20, causing the return spring 20 to accumulate elastic potential energy. When the gas volume in the rectifying column 4 is sufficient, the upward movement stroke of the sealing plunger 28 increases, which in turn causes the top membrane rod 17 to move downward, and the elastic membrane 10 resumes its deformation, making the upper surface of the elastic membrane 10 flush with the upper surface of the fixed ring seat 8. At the same time, the return spring 20 drives the floating ring 9 to move downward, so that the liquid pressing ring plate 16 is snapped into the liquid collecting groove 22. The liquid in the liquid collecting groove 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 perform mass transfer and mixing on the liquid on the surface of the elastic membrane 10.

[0032] It should be noted that in this article, 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 term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including 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 the embodiments of the present invention have been shown and described, those of ordinary skill in the art can 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. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rectification device for the production and preparation of isopropyl isocyanate, comprising a rectification 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, wherein the end of the gas phase inlet (3) is connected to a reboiler (2) in a through manner, and is characterized in that, It further includes: A plurality of fixed ring seats (8) horizontally and fixedly connected to the inner wall of the rectification column (4) in sequence from top to bottom. An annular liquid collection groove (22) is coaxially formed on the upper end surface of the fixed ring seat (8); An elastic membrane (10) coaxially and fixedly connected to the inner wall of the middle hole of the fixed ring seat (8). A plurality of sieve holes are formed on the surface of the elastic membrane (10). 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 arranged in the rectification column (4). The top membrane assembly is used to make the elastic membrane (10) receive an upward longitudinal force, so that the elastic membrane (10) generates an upward bulging elastic extension deformation.

2. The rectification device for the production and preparation of isopropyl isocyanate according to claim 1, wherein, A stirrer (1) is arranged at the bottom of the tower kettle (2).

3. A rectification device for the production and preparation of isopropyl isocyanate according to claim 1, characterized in that, A liquid pressing assembly is arranged on the fixed ring seat (8). The liquid pressing assembly includes a plurality of guide columns (21) vertically and fixedly connected to the upper surface of the fixed ring seat (8). A floating ring (9) is arranged above the fixed ring seat (8). A guide hole for the free passage of the guide column (21) is formed on the floating ring (9). A plurality of vertical pipes (15) are fixedly connected to the lower surface of the floating ring (9). The lower ends of the plurality of vertical pipes (15) are commonly fixedly connected with a liquid pressing ring plate (16). When the liquid pressing ring plate (16) moves downward, it will be clamped into the liquid collection groove (22) and is in sliding fit with the inner wall of the liquid collection groove (22). A floating frame (13) is fixedly connected to the surface of the floating ring (9). The floating frame (13) abuts against the upper surface of the elastic membrane (10). A liquid outlet structure is arranged on the liquid pressing ring plate (16).

4. A rectification device for the production and preparation of isopropyl isocyanate according to claim 3, characterized in that, The liquid outlet structure includes a spray pipe (14) fixedly connected to the outer wall of the vertical pipe (15) in a penetrating manner. The end of the spray pipe (14) far away from the vertical 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 formed on the bottom surface. The liquid inlet holes (23) are communicated with the inner cavity of the liquid pressing ring plate (16) and the vertical pipe (15).

5. A rectification device for the production and preparation of isopropyl isocyanate according to claim 3, characterized in that, A stop ring (19) is fixedly sleeved on the upper end of the guide column (21). A return spring (20) is wound around the periphery of the guide column (21). The two ends of the elastic force direction of the return spring (20) elastically abut against the bottom surface of the stop ring (19) and the top surface of the floating ring (9) respectively.

6. A rectification device for the production and preparation of isopropyl isocyanate according to claim 1, characterized in that, The top membrane assembly includes an upper air gathering cover (12) fixedly connected to the inner wall of the rectification column (4) and abutting against the bottom surface of the fixed ring seat (8). A communication chamber (11) is connected to the bottom of the upper air gathering cover (12) in a penetrating manner. A lower air gathering cover (7) is fixedly connected to the lower end of the communication chamber (11). A sealing part (18) is coaxially fixedly connected to the inner cavity wall of the communication chamber (11). A plurality of air inlet holes (29) are formed on the end surface of the sealing part (18). A top membrane rod (17) is slidably penetrated through the sealing part (18). The top membrane rod (17) is used in cooperation with the elastic membrane (10). An air jacking structure is further arranged on the sealing part (18). The air jacking structure is used to drive the top membrane rod (17) to move up and down.

7. A rectification device for the production and preparation of isopropyl isocyanate according to claim 6, characterized in that, The gas top structure includes a sliding rod (26) vertically slidably penetrating through the sealing part (18). A counterweight plate (27) is fixedly connected to the upper end of the sliding rod (26). A sealing plunger (28) cooperating with the air inlet hole (29) is fixedly connected to the bottom surface of the counterweight plate (27). 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, the top film rod (17) is driven to move synchronously and in the opposite direction.

8. A rectification device for the production and preparation of isopropyl isocyanate according to claim 7, characterized in that, The aperture of the air inlet hole (29) gradually decreases from top to bottom.

9. A rectification device for the production and preparation of isopropyl isocyanate according to claim 7, characterized in that, The transmission unit includes a support arm fixedly connected 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) externally meshing with the transmission gear (25) is provided on the periphery of the top film rod (17). A second rack section (30) externally meshing with 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).

10. A rectification device for the production and preparation of isopropyl isocyanate according to claim 7, 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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