Cyclohexanol dehydrogenation reaction and rectification integrated system

Abstract

The utility model provides a cyclohexanol dehydrogenation reaction and rectification integrated system which comprises a cyclohexanol recovery tower and a heavy component removal tower, the top of the cyclohexanol recovery tower is respectively connected with an alcohol dehydrogenation reactor B and a second reboiler of the light component removal tower through a pressurized gas-phase material via pipelines and an alcohol dehydrogenation reactor A; the light component removal tower second reboiler is connected with the upper part of the cyclohexanol recovery tower through a cyclohexanol recovery tower return tank, the bottom of the cyclohexanol recovery tower is connected with the heavy component removal tower through a pipeline, the top of the heavy component removal tower is connected with a heavy component removal tower return tank through a cyclohexanone product tower third reboiler, and the heavy component removal tower return tank is connected with the upper part of the heavy component removal tower through a pipeline. The device is compact in structure and ingenious in design, the energy utilization rate is greatly increased, stable and efficient production is guaranteed, the manufacturing cost is reduced, and good economic benefits are achieved.

Description

Technical Field

[0001] This utility model relates to the field of chemical production technology, and in particular to an integrated system for cyclohexanol dehydrogenation reaction distillation. Background Technology

[0002] Cyclohexanone is one of the important organic chemical raw materials for the production of caprolactam. In the production process of cyclohexanone, whether it is the oxidative decomposition process or the hydration process, cyclohexanol is produced as a by-product or intermediate product, and then cyclohexanone is produced by the dehydrogenation reaction of cyclohexanol.

[0003] In current cyclohexanol dehydrogenation production processes, two completely independent production systems are commonly used: the cyclohexanol dehydrogenation reaction and the crude alcohol ketone refining system. In the dehydrogenation reactor, about 45% of cyclohexanol is converted into cyclohexanone. The dehydrogenation product, crude alcohol ketone, is then separated into light components, cyclohexanone, cyclohexanol, and heavy components by distillation. The distilled cyclohexanol is combined with fresh cyclohexanol from the previous stage, vaporized in an evaporator, and then sent to the dehydrogenation reactor. In the distillation system, cyclohexanol needs to be processed by a circulating water condenser and a chilled water cooler before being vaporized by steam heating. This process consumes a lot of steam for vaporization heating, and also increases the power cost and treatment cost of circulating water and chilled water.

[0004] Under the current increasingly stringent energy requirements and market competition, the cost of raw material benzene procurement is affected by the uncertainty of changes in the international crude oil market, and with the continuous rise in the procurement cost of raw material coal and the increase in steam heat energy costs, the cyclohexanone industry is facing an increasingly severe situation. Utility Model Content

[0005] This invention provides an integrated system for the dehydrogenation and distillation of cyclohexanol, which solves the technical problems of high energy consumption and high manufacturing costs.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: it includes a cyclohexanol recovery tower and a deweighting tower. The top of the cyclohexanol recovery tower is connected to the alcohol dehydrogenation reactor A and the alcohol dehydrogenation reactor B and the second reboiler of the light-weight removal tower through pipelines via pressurized gaseous material. The second reboiler of the light-weight removal tower is connected to the upper part of the cyclohexanol recovery tower through a reflux tank of the cyclohexanol recovery tower. The bottom of the cyclohexanol recovery tower is connected to the deweighting tower through pipelines. The top of the deweighting tower is connected to the reflux tank of the deweighting tower through a third reboiler of the cyclohexanone product tower. The reflux tank of the deweighting tower is connected to the upper part of the deweighting tower through pipelines.

[0007] In the preferred embodiment, alcohol dehydrogenation reactor A and alcohol dehydrogenation reactor B are connected to an alcohol dehydrogenation heat exchanger via pipelines. The two sides of the alcohol dehydrogenation heat exchanger are connected to a cyclohexanol recovery tower and an alcohol dehydrogenation feed preheater via pipelines, respectively.

[0008] In the preferred embodiment, the cyclohexanol feed is connected to an alcohol dehydrogenation feed preheater and a cyclohexanol recovery tower.

[0009] In the preferred embodiment, the ketone tower reboiler is connected to the cyclohexanol recovery tower via a cyclohexanol recovery tower feed preheater.

[0010] In a preferred embodiment, an alcohol dehydrogenation steam generator is also provided, and the alcohol dehydrogenation steam generator and the cyclohexanol recovery tower feed preheater are connected to the alcohol dehydrogenation discharge separation tank via pipelines.

[0011] In the preferred embodiment, the top pressure of the cyclohexanol recovery tower is not less than 60 kPa.

[0012] In the preferred embodiment, a crude alcohol-ketone preheater is connected to one side of the alcohol dehydrogenation discharge separation tank via a pipeline, and the crude alcohol-ketone preheater is connected to a dehydration tower via a pipeline.

[0013] In a preferred embodiment, the other side of the alcohol dehydrogenation discharge separation tank is connected to the crude alcohol-ketone preheater via an alcohol dehydrogenation product tank and an electric pump unit.

[0014] In the preferred embodiment, the deweight reflux tank is connected to the cyclohexanol recovery tower via an electric pump unit.

[0015] In the preferred embodiment, the bottom of the de-oiling tower is connected to a heavy oil storage tank via an electric pump unit.

[0016] The beneficial effects of this utility model are as follows: by modifying the traditional process, the alcohol conversion evaporator is eliminated, the condenser of the cyclohexanol recovery tower is reduced, steam consumption and condenser circulating water consumption are reduced, the thermal energy utilization of the three high-temperature materials—the top gas phase of the cyclohexanol recovery tower, the top gas phase of the deweighting tower, and the effluent from the dehydrogenation reactor—is improved, the system heating steam consumption is reduced, the load on the condenser and cooler is reduced, the circulating water consumption of the condenser and cooler is reduced, and energy consumption is reduced, resulting in good economic benefits. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0018] Figure 1 This is a schematic diagram of the structural layout of this utility model;

[0019] Figure 2 This is a schematic diagram of the traditional process flow;

[0020] Figure 3 This is a schematic diagram of the process flow of this utility model.

[0021] In the diagram: 1. Cyclohexanol recovery tower; 2. Heavy removal tower; 3. Alcohol dehydrogenation reactor A; 4. Alcohol dehydrogenation reactor B; 5. Alcohol dehydrogenation heat exchanger; 6. Alcohol dehydrogenation steam generator; 7. Alcohol dehydrogenation feed preheater; 8. Cyclohexanol recovery tower feed preheater; 9. Alcohol dehydrogenation discharge separator; 10. Crude alcohol-ketone preheater; 11. Second reboiler for light removal tower; 12. Cyclohexanol recovery tower reflux tank; 13. Third reboiler for cyclohexanone product tower; 14. Heavy removal tower reflux tank; 15. Electric pump unit; 16. Ketone tower reboiler; 17. Cyclohexanol feed; 18. Dehydration tower; 19. Alcohol dehydrogenation product tank; 20. Heavy oil storage tank; 21. Hydrogen compressor. Detailed Implementation

[0022] like Figure 1 As shown, an integrated cyclohexanol dehydrogenation reactive distillation system includes a cyclohexanol recovery tower 1 and a heavy phase removal tower 2. The top of the cyclohexanol recovery tower 1 is connected via pipelines to the alcohol dehydrogenation reactor A3, alcohol dehydrogenation reactor B4, and the second reboiler 11 of the light phase removal tower. The second reboiler 11 is connected to the upper part of the cyclohexanol recovery tower 1 via a cyclohexanol recovery tower reflux tank 12. The bottom of the cyclohexanol recovery tower 1 is connected to the heavy phase removal tower 2 via pipelines. The top of the heavy phase removal tower 2 is connected to the third reboiler 13 of the cyclohexanone product tower and the heavy phase removal tower reflux tank 14 via pipelines. The heavy phase removal tower reflux tank 14 is connected to the upper part of the heavy phase removal tower 2 via pipelines. An electric pump unit 15 serves as the driving component for liquid supply and recovery, ensuring stable flow rates in each loop to meet production needs.

[0023] like Figure 2 In the middle, the traditional production process requires an evaporator to ensure energy supply, and this process consumes a lot of energy, such as... Figure 3 The process described in this application reduces energy consumption. In addition to the second reboiler in the light tower, it comprehensively utilizes the gas phase heat at the top of the cyclohexanol recovery tower, and at the same time, it better exchanges energy between cyclohexanol in different states, ensuring stable and efficient production.

[0024] The gas phase from the top of the cyclohexanol recovery tower, which is used as the reflux liquid, is used as the heat source for heating the light-light removal tower. A second reboiler for the light-light removal tower is designed to reduce the design cost of the first reboiler.

[0025] Adjusting the required circulating water volume for the top condenser of the cyclohexanol recovery tower, while ensuring the exhaust temperature meets the standard, can reduce the operating and management costs of the circulating water system.

[0026] Using the top gas phase of the deweighting tower as the heat source for the cyclohexanone product tower, the operating pressure at the top of the deweighting tower was determined, and the third reboiler for the cyclohexanone product tower was designed.

[0027] In a copper-silicon catalyst fixed bed, gaseous cyclohexanol undergoes partial dehydrogenation to produce cyclohexanone and hydrogen. The reaction temperature is controlled at 210℃-260℃, and the reaction pressure is controlled at 60 kPaG. This reaction is endothermic, and the heat required for the reaction is provided by a thermal oil heater through the combustion of fuel gas / fuel oil.

[0028] In the preferred embodiment, alcohol dehydrogenation reactor A3 and alcohol dehydrogenation reactor B4 are connected to alcohol dehydrogenation heat exchanger 5 via pipelines. The two sides of alcohol dehydrogenation heat exchanger 5 are connected to cyclohexanol recovery tower 1 and alcohol dehydrogenation feed preheater 7 via pipelines, respectively.

[0029] By setting up the alcohol dehydrogenation heat exchanger 5, the stability of the reaction process is ensured, while the energy utilization rate is improved and the system steam loss is reduced.

[0030] In a preferred embodiment, the cyclohexanol feed 17 is connected to the alcohol dehydrogenation feed preheater 7 and the cyclohexanol recovery tower 1.

[0031] In a preferred embodiment, the ketone tower bottom 16 is connected to the cyclohexanol recovery tower 1 via the cyclohexanol recovery tower feed preheater 8.

[0032] In a preferred embodiment, an alcohol dehydrogenation steam generator 6 is also provided. The alcohol dehydrogenation steam generator 6 and the cyclohexanol recovery tower feed preheater 8 are respectively connected to the alcohol dehydrogenation discharge separation tank 9 via pipelines.

[0033] By setting up the above-mentioned alcohol dehydrogenation feed preheater, cyclohexanol recovery tower feed preheater, and alcohol dehydrogenation steam generator, the steam consumption of the cyclohexanol recovery tower is reduced by controlling the temperature of the two streams of feed to the cyclohexanol recovery tower; the alcohol dehydrogenation steam generator produces a by-product of 0.3 MPa, which further reduces the steam consumption of the cyclohexanol product tower.

[0034] In the preferred embodiment, the top pressure of the cyclohexanol recovery tower 1 is not less than 60 kPa. The dehydrogenation reaction is a volume-reducing reaction; to ensure the conversion rate, the system pressure is generally controlled at around 5-10 kPa. The catalyst pressure difference in the dehydrogenation reactor bed is generally within 50 kPa. Therefore, the pressure of the gaseous cyclohexanol feed to the dehydrogenation reactor needs to be controlled at 60 kPa to ensure stable and efficient separation of cyclohexanol and heavy components.

[0035] In the preferred embodiment, a crude alcohol-ketone preheater 10 is connected to one side of the alcohol dehydrogenation discharge separation tank 9 via a pipeline, and the crude alcohol-ketone preheater 10 is connected to a dehydration tower 18 via a pipeline. After the crude alcohol-ketone preheater 10 exchanges heat with the crude alcohol-ketone in the product tank after being pressurized by the alcohol dehydrogenation discharge pump, the gas phase then passes through the alcohol dehydrogenation condenser and the alcohol dehydrogenation tail cooler in sequence for condensation and cooling. The separated liquid returns to the dehydrogenation product tank, and the gas phase is mainly dehydrogenation by-product hydrogen. After being pressurized by the hydrogen compressor 21, it is sent to the hydrogen purification system to recover hydrogen.

[0036] In a preferred embodiment, the other side of the alcohol dehydrogenation discharge separation tank 9 is connected to the crude alcohol ketone preheater 10 via the alcohol dehydrogenation product tank 19 and the electric pump unit 15.

[0037] In a preferred embodiment, the deweight reflux tank 14 is connected to the cyclohexanol recovery tower 1 via an electric pump unit 15.

[0038] Based on the separation status of heavy components and cyclohexanol in the bottom of the column, the design of the heavy removal column was re-optimized to recover cyclohexanol from the heavy oil output in the bottom of the column and improve the utilization rate of raw materials.

[0039] In the preferred embodiment, the bottom of the de-oiling tower 2 is connected to a heavy oil storage tank 20 via an electric pump unit 15.

[0040] Process flow description:

[0041] The fresh cyclohexanol feed to the original alcohol conversion evaporator is changed to be used as reflux liquid at the top of the cyclohexanol recovery tower. Most of the gaseous material pressurized to 60 kPa at the top of the cyclohexanol recovery tower is directly used as feed to the dehydrogenation reactor. The other part enters the second reboiler of the light removal tower and exchanges heat with the bottom material of the light removal tower before returning to the reflux tank of the cyclohexanol recovery tower. It is then pumped to the top of the tower by the cyclohexanol recovery tower reflux pump as another part of the reflux liquid.

[0042] After the cyclohexanol gas phase undergoes a dehydrogenation reaction catalyzed by the catalyst in the dehydrogenation reactor, the high-temperature material is divided into three parts: one part exchanges heat with the fresh cyclohexanol feed, heating the cyclohexanol feedstock from room temperature to 170°C, and then sends it to the cyclohexanol recovery tower as reflux liquid; the second part exchanges heat with the material at the bottom of the cyclohexanone product tower, heating the mixture of cyclohexanol and heavy components at approximately 90°C at the bottom of the cyclohexanone product tower to 160°C, and then enters the middle of the cyclohexanol recovery tower; after the heat exchange in the first two parts, the material with excess heat from the dehydrogenation reaction product enters the alcohol dehydrogenation steam generator, and after exchanging heat with the steam condensate of the unit, 0.3MPa steam is produced as a byproduct, which is used for the first reboiler of the cyclohexanone product tower, reducing the amount of 0.3MPa steam used in the inner and outer tubes of the original cyclohexanone product tower first reboiler.

[0043] After heat exchange, these three materials enter the alcohol dehydrogenation discharge separator. In the separator, gas-liquid separation is carried out. The liquid phase enters the dehydrogenation product tank, while the gas phase exchanges heat with the crude alcohol ketone in the crude alcohol ketone preheater after being pressurized by the alcohol dehydrogenation discharge pump in the product tank. The gas phase then passes through the alcohol dehydrogenation condenser and alcohol dehydrogenation tail cooler in sequence for condensation and cooling. The separated liquid returns to the dehydrogenation product tank. The gas phase is mainly hydrogen, a by-product of dehydrogenation. After being pressurized by the compressor, it is sent to the hydrogen purification system to recover hydrogen.

[0044] The heavy oil containing cyclohexanol in the bottom of the cyclohexanol recovery tower is pumped to the deweighting tower for further separation of cyclohexanol and heavy components. The vapor from the top of the deweighting tower enters the third reboiler of the cyclohexanone product tower. After heat exchange with the bottom material of the cyclohexanone product tower, it returns to the reflux tank of the deweighting tower and is then pumped to the top of the tower as reflux liquid by the deweighting tower reflux pump.

[0045] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The protection scope of this utility model should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. An integrated system for the dehydrogenation reactive distillation of cyclohexanol, characterized in that: The cyclohexanol recovery tower (1) and the deweight tower (2) are included. The top of the cyclohexanol recovery tower (1) is connected to the alcohol dehydrogenation reactor B (4) and the second reboiler (11) of the light removal tower through the pressurized gaseous material via pipelines and alcohol dehydrogenation reactor A (3). The second reboiler (11) of the light removal tower is connected to the upper part of the cyclohexanol recovery tower (1) through the cyclohexanol recovery tower reflux tank (12). The bottom of the cyclohexanol recovery tower (1) is connected to the deweight tower (2) through pipelines. The top of the deweight tower (2) is connected to the deweight tower reflux tank (14) through the cyclohexanone product tower third reboiler (13). The deweight tower reflux tank (14) is connected to the upper part of the deweight tower (2) through pipelines.

2. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 1, characterized in that: The alcohol dehydrogenation reactor A (3) and the alcohol dehydrogenation reactor B (4) are connected to the alcohol dehydrogenation heat exchanger (5) through pipelines. The two sides of the alcohol dehydrogenation heat exchanger (5) are connected to the cyclohexanol recovery tower (1) and the alcohol dehydrogenation feed preheater (7) through pipelines, respectively.

3. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 2, characterized in that: The cyclohexanol feed (17) is connected to the alcohol dehydrogenation feed preheater (7) and the cyclohexanol recovery tower (1).

4. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 3, characterized in that: The ketone tower bottom (16) is connected to the cyclohexanol recovery tower feed preheater (8) and the cyclohexanol recovery tower (1).

5. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 4, characterized in that: It is also equipped with an alcohol dehydrogenation steam generator (6), and the alcohol dehydrogenation steam generator (6) and the cyclohexanol recovery tower feed preheater (8) are connected to the alcohol dehydrogenation discharge separation tank (9) through pipelines.

6. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 5, characterized in that: The pressure at the top of the cyclohexanol recovery tower (1) shall not be less than 60 kPa.

7. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 5, characterized in that: A crude alcohol-ketone preheater (10) is connected to one side of the alcohol dehydrogenation discharge separation tank (9) via a pipeline, and the crude alcohol-ketone preheater (10) is connected to a dehydration tower (18) via a pipeline.

8. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 7, characterized in that: The other side of the alcohol dehydrogenation discharge separator (9) is connected to the crude alcohol ketone preheater (10) via the alcohol dehydrogenation product tank (19) and the electric pump unit (15).

9. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 1, characterized in that: The deweight tower reflux tank (14) is connected to the cyclohexanol recovery tower (1) via an electric pump unit (15).

10. The integrated cyclohexanol dehydrogenation reactive distillation system according to claim 1, characterized in that: The bottom of the deweight tower (2) is connected to a heavy oil storage tank (20) via an electric pump unit (15).

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