Catalytic rectifying separation device for cyclohexene esterification reaction

Abstract

The application relates to the field of cyclohexene esterification technology, and provides a cyclohexene esterification reaction catalytic rectification separation device, which comprises a reaction rectification tower and a material circulating pump, the bottom of the reaction rectification tower is connected with the material circulating pump through a first pipeline, a second pipeline is arranged in parallel on the first pipeline, a buffer tank is arranged on the second pipeline, the buffer tank is provided with an inlet at the bottom and an outlet at the top; a filter screen is arranged in the buffer tank; first and second valves are arranged on the first pipeline at intervals, one end of the second pipeline is connected between the first and second valves, and a third valve is arranged on the second pipeline. By arranging a buffer tank in parallel, the filter screen arranged in the buffer tank can filter solid substances such as catalysts, can effectively prevent the catalysts from flowing into the next process unit, can ensure the normal operation of the next process unit and the product quality, and can ensure the continuity of the device operation by switching the valves to clean the buffer tank at any time according to the existing process technology.

Description

Technical Field

[0001] This application belongs to the field of cyclohexene esterification technology, and more specifically, relates to a catalytic distillation and separation device for cyclohexene esterification reaction. Background Technology

[0002] Cyclohexanone is an important organic chemical raw material and an intermediate in the production of caprolactam, adipic acid, and other chemical products such as pharmaceuticals, coatings, and dyes. It plays a crucial role in the textile and coating industries. Currently, the main production methods for cyclohexanone include cyclohexane oxidation, phenol hydrogenation, and cyclohexene hydration.

[0003] The cyclohexene esterification and hydrogenation to cyclohexanone technology is one of the green production technologies for caprolactam developed in recent years. It includes four reaction steps: selective hydrogenation of benzene, cyclohexene esterification, hydrogenation of cyclohexyl acetate, and dehydrogenation of cyclohexanol. The cyclohexene esterification and hydrogenation reactions exhibit extremely high conversion rates and selectivity. The reaction conditions are relatively mild, carbon atom utilization is high, and the generation of waste during the production process is low. It also has high atom economy, converting inexpensive raw material acetic acid into the more valuable byproduct ethanol.

[0004] The operation of China's first industrial-scale cyclohexene esterification and hydrogenation production unit has revealed several issues. Due to the long-term operation of the reactive distillation column, some damaged catalyst and impurities are carried along with the esterification products into the next process unit (cyclohexyl acetate refining and hydrogenation unit), resulting in catalyst loss and accelerating the cleaning and maintenance of the material circulation pump. Furthermore, the catalyst's entry into the next process unit leads to incomplete separation and purification of subsequent products, ultimately affecting the normal operation of the next process unit and the quality of the cyclohexanone product. Utility Model Content

[0005] In view of the technical problem in the prior art that the catalyst in the reactive distillation column will flow into the next process unit and cause adverse effects, the purpose of this application is to provide a catalytic distillation separation device for cyclohexene esterification reaction, which adds a buffer tank and sets a filter screen in the buffer tube to filter the lost catalyst, thereby ensuring the normal operation of the next process unit and ensuring product quality.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: a catalytic distillation separation device for cyclohexene esterification reaction is provided, comprising: a reactive distillation column and a material circulation pump. The bottom of the reactive distillation column is connected to the material circulation pump through a first pipe. A second pipe is connected in parallel on the first pipe. A buffer tank is provided on the second pipe. The buffer tank is fed from the bottom and discharged from the top. A filter screen is provided inside the buffer tank. A first valve and a second valve are provided at intervals on the first pipe. One end of the second pipe is connected between the first valve and the second valve. A third valve is provided on the second pipe.

[0007] In one embodiment, the filter mesh is provided with three layers, and the pore size of the three layers of filter mesh gradually decreases from bottom to top.

[0008] In one embodiment, the lower layer of filter mesh has a pore size of 0.28-0.25 mm, the middle layer of filter mesh has a pore size of 0.15-0.18 mm, and the upper layer of filter mesh has a pore size of 0.125-0.18 mm.

[0009] In one embodiment, the buffer tank is provided with a perforated plate, and the filter mesh is fixedly supported by the perforated plate.

[0010] In one embodiment, the buffer tank is provided with a radial protruding ring, the perforated plate is placed on the radial protruding ring, and the perforated plate and the filter screen are fixed on the radial protruding ring by bolts.

[0011] In one embodiment, two perforated plates are provided, and three layers of filter mesh are disposed between the two perforated plates. The upper surface of the upper perforated plate is provided with a plurality of reinforcing ribs, and the lower surface of the lower perforated plate is provided with a plurality of reinforcing ribs.

[0012] In one embodiment, the buffer tank is a titanium tank.

[0013] In one embodiment, the material circulation pump is a centrifugal pump or a reciprocating pump, and the inlet pipe of the material circulation pump is equipped with a pipeline filter.

[0014] In one embodiment, two buffer tanks are arranged in parallel.

[0015] In one embodiment, the buffer tank has a catalyst drain port at the bottom of its axis and a liquid discharge port at the bottom of the buffer tank. The liquid discharge port is offset from the axis and is positioned higher than the catalyst drain port.

[0016] The beneficial effects of the cyclohexene esterification reaction catalytic distillation separation device provided in this application are as follows: by connecting a buffer tank in parallel with the existing process, the buffer tank is equipped with a filter screen to filter solid substances such as catalysts, which can effectively prevent the catalyst from flowing into the next process unit, ensuring the normal operation of the next process unit and ensuring product quality; at the same time, by switching valves, the buffer tank can be switched out of the existing process for cleaning at any time, ensuring the continuity of the device's operation, which is simple to operate and saves operating costs and labor. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a simplified flow diagram of the catalytic distillation and separation apparatus for the cyclohexene esterification reaction provided in Example 1 of this application;

[0019] Figure 2 This is a schematic diagram of the structure of the buffer tank with a filter screen installed in the catalytic distillation and separation device for the cyclohexene esterification reaction provided in Example 1 of this application;

[0020] Figure 3 This is a top view of the orifice plate in the catalytic distillation and separation device for cyclohexene esterification provided in Example 1 of this application.

[0021] Figure 4 This is a simplified flow diagram of the catalytic distillation and separation apparatus for the cyclohexene esterification reaction provided in Example 2 of this application;

[0022] Figure 5 This is a simplified process diagram of the catalytic distillation and separation device for the cyclohexene esterification reaction provided in Example 3 of this application.

[0023] The following are the labeling elements in the figure:

[0024] 1. Reactive distillation column; 2. Material circulation pump; 3. First pipeline; 4. Second pipeline; 5. Buffer tank; 6. Filter screen; 7. First valve; 8. Second valve; 9. Third valve; 10. Radial convex ring; 11. Orifice plate; 12. Bolt; 13. Gasket; 14. Reinforcing rib; 15. Pipeline filter; 16. Catalyst discharge port; 17. Liquid discharge port; 18. Third pipeline; 19. Fourth valve; 20. Fifth valve. Detailed Implementation

[0025] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0026] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0027] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0029] Example 1:

[0030] like Figures 1-3 As shown, a catalytic distillation separation device for cyclohexene esterification reaction provided in Embodiment 1 of this application will now be described. This catalytic distillation separation device for cyclohexene esterification reaction includes a reactive distillation column 1 and a material circulation pump 2. The bottom of the reactive distillation column 1 is connected to the material circulation pump 2 via a first pipe 3, and the outlet of the material circulation pump 2 is connected to the next process unit. A second pipe 4 is connected in parallel to the first pipe 3, and a buffer tank 5 is installed on the second pipe 4. The buffer tank 5 has a bottom feed and a top discharge. A filter screen 6 is installed inside the buffer tank 5. A first valve 7 and a second valve 8 are spaced apart on the first pipe 3. One end of the second pipe 4 is connected between the first valve 7 and the second valve 8. A third valve 9 is installed on the second pipe 4, located at the feed inlet of the buffer tank 5. Under normal operating conditions, valves 7 and 9 are open, while valve 8 is closed. The reaction solution is pumped into the reactive distillation column 1 via a feed pump. Within the column, the reaction solution undergoes a catalytic reaction to produce a mixture of cyclohexyl acetate and acetic acid. This mixture (containing damaged catalyst and other solid impurities) flows into buffer tank 5 through valves 7 and 9. In buffer tank 5, the catalyst and solid impurities are precipitated and filtered through a filter screen 6, separating the cyclohexyl acetate and acetic acid from the damaged catalyst and other solid impurities. The filtered cyclohexyl acetate and acetic acid are then pumped to the next process unit via a material circulation pump 2. When cleaning of buffer tank 5 is required, valve 8 is opened and valve 9 is closed, allowing for online cleaning of buffer tank 5, bypassing the existing process flow.

[0031] A catalyst drain port 16 is located at the bottom of the buffer tank 5 along its axis, and a liquid discharge port 17 is located at the bottom of the buffer tank 5. Valves are installed on the pipes of both the catalyst drain port 16 and the liquid discharge port 17. The liquid discharge port 17 is offset from the axis and is positioned higher than the catalyst drain port 16. Therefore, during online cleaning, the liquid in the buffer tank 5 is first discharged to the collection system through the liquid discharge port 17. After the liquid is discharged, the catalyst drain port 16 is opened to discharge all the catalyst and other solid impurities in the buffer tank 5. Cleaning is then performed by introducing cleaning water from the top.

[0032] In this embodiment, the catalyst packed in the reactive distillation column 1 has a diameter of 0.25-1.25 mm. The filter mesh 6 consists of three layers, with the pore size gradually decreasing from bottom to top. Specifically, the bottom layer filter mesh 6 has a pore size of 0.28-0.25 mm, the middle layer has a pore size of 0.15-0.18 mm, and the top layer has a pore size of 0.125-0.18 mm. The three layers of filter mesh 6 effectively filter out the catalyst.

[0033] In this embodiment, a perforated plate 11 is provided inside the buffer tank 5. The perforated plate 11 has several through holes with a diameter of 6-8 mm. The filter mesh 6 is fixedly supported inside the buffer tank 5 through the perforated plate 11.

[0034] Preferably, the buffer tank 5 is provided with a radial protruding ring 10, and the perforated plate 11 is placed on the radial protruding ring 10. The perforated plate 11 and the filter mesh 6 are fixed to the radial protruding ring 10 by bolts 12 arranged at intervals. This facilitates the assembly of the perforated plate 11 and the filter mesh 6. Furthermore, two perforated plates 11 are provided, and the three-layer filter mesh 6 is arranged between the two perforated plates 11. The two perforated plates 11 are used to clamp the three-layer filter mesh 6 to ensure the flatness of the three-layer filter mesh 6. A gasket 13 is also provided on the radial protruding ring 10, and the lower perforated plate 11 is placed on the gasket 13. The radial convex ring 10 is welded to the inner wall of the buffer tank 5; the nut of the bolt 12 is located on the lower surface of the radial convex ring 10, and the nut is welded to the lower surface of the radial convex ring 10; during assembly, the gasket 13, the lower perforated plate 11, the three-layer filter mesh 6, and the upper perforated plate 11 are respectively fitted onto the bolt 12, and then a nut is screwed onto the bolt to tighten the upper perforated plate 11, completing the assembly. Preferably, the circumferential surface of the three-layer filter mesh 6 is bent upwards to ensure that the three-layer filter mesh 6 is in close contact with the inner wall of the buffer tank 5. The function of the upper perforated plate 11 and the lower perforated plate 11 is to ensure the flatness of the three-layer filter mesh 6.

[0035] To ensure the deformation resistance of the perforated plate 11, the upper surface of the upper perforated plate 11 is provided with a number of reinforcing ribs 14, and the lower surface of the lower perforated plate 11 is provided with a number of reinforcing ribs 14, which are arranged in a grid pattern.

[0036] In this embodiment, the buffer tank 5 is a titanium tank, preferably a TA2G tank. The material circulation pump 2 is a centrifugal pump or a reciprocating pump, and a pipeline filter 15 is installed on the inlet pipe of the material circulation pump 2 to protect it.

[0037] In other embodiments, two buffer tanks 5 are arranged in parallel, and there are two parallel connection methods, one as shown in Embodiment 2 and the other as shown in Embodiment 3.

[0038] Example 2:

[0039] like Figure 4 As shown, the difference between this embodiment and Embodiment 1 is that two buffer tanks 5 are arranged in parallel. Specifically, a buffer tank 5 is also provided in the first pipeline 3, and valves are provided at the outlets of both buffer tanks 5. Thus, when one buffer tank 5 is in use, the other buffer tank 5 serves as a backup tank, and the outlet valve of the backup tank is closed. During online cleaning, the usage status of the two buffer tanks 5 is changed by alternating the opening and closing states of the second valve 8 and the third valve 9, so that the two buffer tanks 5 can be used and cleaned alternately.

[0040] Example 3:

[0041] like Figure 5 As shown, the difference between this embodiment and embodiment 1 is that a buffer tank 5 is connected in parallel by adding a third pipe 18. The third pipe 18 is connected in parallel with the second pipe 4, so that the two buffer tanks 5 are connected in parallel. The outlets of the two buffer tanks 5 are equipped with valves. A fourth valve 19 is provided on the second pipe 4, and a fifth valve 20 is provided on the third pipe 18. The third pipe 18 is located between the third valve 9 and the fourth valve 19. In this way, the usage state of the two buffer tanks 5 can be changed by changing the opening and closing state of the fourth valve 19 and the fifth valve 20, so that the two buffer tanks 5 can be used and cleaned alternately, so as to achieve continuous operation of the device. This embodiment also retains the original process flow.

[0042] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A catalytic distillation and separation apparatus for cyclohexene esterification reaction, comprising: A reactive distillation column (1) and a material circulation pump (2) are provided. The bottom of the reactive distillation column (1) is connected to the material circulation pump (2) through a first pipe (3). The first pipe (3) is connected in parallel with a second pipe (4). A buffer tank (5) is provided on the second pipe (4). The buffer tank (5) is fed from the bottom and discharged from the top. A filter screen (6) is provided inside the buffer tank (5). A first valve (7) and a second valve (8) are provided at intervals on the first pipe (3). One end of the second pipe (4) is connected between the first valve (7) and the second valve (8). A third valve (9) is provided on the second pipe (4).

2. The catalytic distillation and separation apparatus for cyclohexene esterification reaction as described in claim 1, characterized in that: The filter mesh (6) has three layers, and the pore size of the three layers of filter mesh (6) gradually decreases from bottom to top.

3. The catalytic distillation and separation apparatus for cyclohexene esterification reaction as described in claim 2, characterized in that: The lower layer of filter mesh (6) has a pore size of 0.28-0.25 mm, the middle layer of filter mesh (6) has a pore size of 0.15-0.18 mm, and the upper layer of filter mesh (6) has a pore size of 0.125-0.18 mm.

4. The catalytic distillation and separation apparatus for cyclohexene esterification reaction as described in claim 3, characterized in that: The buffer tank (5) is provided with a perforated plate (11), and the filter mesh (6) is fixedly supported by the perforated plate (11).

5. The catalytic distillation and separation apparatus for cyclohexene esterification reaction as described in claim 4, characterized in that: The buffer tank (5) is provided with a radial protruding ring (10), and the perforated plate (11) is placed on the radial protruding ring (10). The perforated plate (11) and the filter screen (6) are fixed on the radial protruding ring (10) by bolts (12).

6. The catalytic distillation and separation apparatus for cyclohexene esterification reaction as described in claim 5, characterized in that: Two perforated plates (11) are provided, and three layers of filter mesh (6) are provided between the two perforated plates (11). The upper surface of the upper perforated plate (11) is provided with several reinforcing ribs (14), and the lower surface of the lower perforated plate (11) is provided with several reinforcing ribs (14).

7. The catalytic distillation and separation apparatus for cyclohexene esterification reaction as described in claim 1, characterized in that: The buffer tank (5) is a titanium tank.

8. The catalytic distillation and separation apparatus for cyclohexene esterification reaction as described in claim 1, characterized in that: The material circulation pump (2) is a centrifugal pump or a reciprocating pump, and a pipeline filter (15) is provided on the inlet pipe of the material circulation pump (2).

9. The catalytic distillation and separation apparatus for the cyclohexene esterification reaction as described in any one of claims 1-8, characterized in that: The buffer tanks (5) are arranged in parallel in two.

10. The catalytic distillation and separation apparatus for cyclohexene esterification reaction as described in claim 9, characterized in that: The buffer tank (5) has a catalyst discharge port (16) at the bottom of its axis and a liquid discharge port (17) at the bottom of its axis. The liquid discharge port (17) is offset from the axis and is positioned higher than the catalyst discharge port (16).

Images