High-temperature ammoximation reaction heat utilization system

Abstract

The utility model relates to the technical field of caprolactam, and particularly provides a high-temperature ammoximation reaction heat utilization system, which comprises an ammoximation reaction kettle and an evaporation tower, a circulating pipeline and a circulating pump are arranged at the lower part of the reaction kettle, an evaporation tower reboiler is arranged in the evaporation tower, an outlet of the circulating pump is connected with an inlet of the evaporation tower reboiler, and the circulating pump is connected with the evaporation tower reboiler. An outlet of the evaporation tower reboiler is connected to a material return port of the ammoximation reaction kettle after passing through a condenser; a steam outlet is formed in the top of the evaporation tower and is connected to a gas pipeline. On the basis of heterogeneous ammoximation, the temperature of a reaction system is increased, high-pressure water vapor is directly generated by reaction heat, the water vapor is used for supplying heat to other sections of caprolactam, the use amount of ammoximation circulating water is reduced, the overall energy consumption of caprolactam is reduced, and the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of caprolactam technology and relates to a high-temperature ammonia oxime reaction heat utilization system. Background Technology

[0002] Caprolactam is an important chemical raw material used in the production of nylon 6 fibers and nylon 6 engineering plastics, and is widely used in industries such as spinning, tires, and food packaging. Currently, there are two methods for the industrial production of caprolactam through ammonoximation. The first is a homogeneous ammonoximation process, using TiSi-1 as a catalyst, with the ammonoximation reaction carried out in tert-butanol solvent at an operating pressure of 0.1-0.2 MPa and an operating temperature of 85-91℃. Ammonoximation is an exothermic reaction, with the rearrangement reaction releasing 301 kJ / mol of cyclohexanone oxime. During the ammonoximation process, the heat generated is first removed through an external circulation loop, and then further removed through a reactor cooler using cooling water, resulting in direct heat waste. The second method employs a heterogeneous ammonia oximation reaction. Compared to the first process, it eliminates tert-butanol and uses Ti / Si molecular sieves as a catalyst. In this process, the system is mostly water. Water has a high calorific value and can better store and transfer heat. However, the ammonia-containing wastewater from the heterogeneous ammonia oximation unit needs to undergo ammonia removal treatment. The ammonia stripping tower uses steam to heat and vaporize the wastewater to remove ammonia, and the wastewater is then sent to the sewage treatment unit. This consumes a large amount of steam, and the wastewater also requires treatment. Summary of the Invention

[0003] This invention provides a high-temperature ammonium oxime reaction heat utilization system. Based on heterogeneous ammonium oxime reaction, the system increases the temperature of the reaction system and uses the reaction heat to directly generate high-pressure steam. The steam is used to heat other stages of caprolactam production, reducing the amount of circulating water used in the ammonium oxime reaction, lowering the overall energy consumption of caprolactam, and reducing costs.

[0004] This invention provides a high-temperature ammonium oximation reaction heat utilization system, including an ammonium oximation reactor and an evaporation tower. The reactor is equipped with a circulation pipe and a circulation pump at the bottom. The evaporation tower is equipped with an evaporation tower reboiler. The outlet of the circulation pump is connected to the inlet of the evaporation tower reboiler. The outlet of the evaporation tower reboiler is connected to the return port of the ammonium oximation reactor after passing through a condenser. The top of the evaporation tower is equipped with a steam outlet, which is connected to the gas supply pipeline.

[0005] Optionally, the reboiler of the evaporator is located on the inner side of the lower part of the evaporator.

[0006] Optionally, the reboiler of the evaporator is a U-tube type, and the liquid circulating from the ammonia oxime reaction vessel passes through the shell side of the reboiler for heat exchange.

[0007] Optionally, the evaporation tower is a packed tower.

[0008] Optionally, the gas pipeline includes users of the deammoniation tower, caprolactam unit steam users, and / or ammonium sulfate unit steam users.

[0009] Optionally, the deammoniation tower user has a deammoniation tower with an external deammoniation tower reboiler. The bottom outlet of the deammoniation tower is connected to the deammoniation tower reboiler via a pipeline and pump, and then returns to the deammoniation tower inlet.

[0010] Optionally, the steam pipe exiting the evaporator is connected to the condensate collection tank after heat exchange with the reboiler of the deammoniation tower.

[0011] Optionally, the deammoniation tower is a packed tower.

[0012] This utility model has the following beneficial effects:

[0013] The system provided by this invention addresses the heat generated in the ammonia oxime reaction vessel by promptly drawing out the feed liquid for heat exchange with the evaporator and reboiler. The heat is absorbed by the water in the evaporator to generate steam. After heat exchange, the feed liquid in the reaction vessel is further condensed and returned to the reaction vessel for further heat exchange. The steam generated in the evaporator is directly used in the deammoniation tower, caprolactam unit, and / or ammonium sulfate unit. By directly combining the heat generation unit with the heat consumption unit, the system can significantly reduce steam consumption, reduce circulating water consumption, and lower the production cost of caprolactam. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model. In the figure, 1 is an ammonia oxime reaction vessel, 2 is a circulating pump, 3 is a condenser, 4 is an evaporator, 5 is an evaporator reboiler, 6 is a deammoniation tower, 7 is a deammoniation tower reboiler, and 8 is a condensate collection tank. Detailed Implementation

[0015] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0016] A high-temperature ammonia oximation reaction heat utilization system includes an ammonia oximation reactor and an evaporation tower. A circulation pipeline and a circulation pump are located at the bottom of the reactor. An evaporation tower reboiler is installed inside the evaporation tower. The outlet of the circulation pump is connected to the inlet of the evaporation tower reboiler. The outlet of the evaporation tower reboiler is connected to the return port of the ammonia oximation reactor after passing through a condenser. A steam outlet is located at the top of the evaporation tower and connected to a gas supply pipeline. The ammonia oximation reactor is a pressure vessel containing hydrogen peroxide, gaseous ammonia, and cyclohexanone feedstock. The reaction temperature is 115-130℃, the operating pressure is 0.5-0.6 MPa, and the reactor liquid temperature is 120-130℃. The reaction generates a large amount of heat, which is carried away by the high-flow-rate feed liquid circulation. The steam generated in the evaporation tower is 120-130℃ and can be directly used for ammonia desorption (ammonia removal tower) in the ammonia oximation unit, the caprolactam unit, and the ammonium sulfate unit. The system directly converts the heat of the ammonia oximation reaction into steam, reducing circulating water consumption and the steam required by the caprolactam unit.

[0017] In some embodiments, the reboiler of the evaporator is located inside the lower part of the evaporator. The feed liquid in the reactor undergoes heat exchange directly in the reboiler, and the exchanged heat is directly used to produce steam.

[0018] In some embodiments, the reboiler of the evaporator is a U-tube type, and the liquid circulating from the ammonia oxime reaction vessel passes through the shell side of the reboiler for heat exchange.

[0019] In some embodiments, the evaporation tower is a packed tower.

[0020] The ammonia removal tower uses steam to heat and vaporize wastewater, removing ammonia, and then the wastewater is sent to the sewage treatment unit. This requires a large amount of steam, and the wastewater also needs treatment. The ammonium sulfate unit's sulfurization drying bed and mother liquor heater both use steam heating, resulting in high energy consumption. The caprolactam refining unit's benzene stripping, benzene residue distillation, hexane evaporation, and pre-evaporation all require large amounts of steam, leading to high energy consumption. In some embodiments, the steam pipeline includes users of the ammonia removal tower, caprolactam unit steam users, and / or ammonium sulfate unit steam users. This system can reduce the amount of steam required in this stage.

[0021] In some embodiments, the deammoniation tower user has a deammoniation tower with an external deammoniation tower reboiler. The bottom outlet of the deammoniation tower is connected to the deammoniation tower reboiler via a pipeline and a pump, and then returns to the deammoniation tower inlet.

[0022] In some embodiments, the steam pipe exiting the evaporator exchanges heat with the reboiler of the deammoniation tower and is then connected to the condensate collection tank.

[0023] In some embodiments, the ammonia removal tower is a packed tower. It uses standard Pall ring packing, has a tower diameter of 1000-1200 mm, and operates at atmospheric pressure.

[0024] The high-temperature ammonium oxime thermal energy utilization system provided by this utility model has a short process flow, low steam consumption, low equipment investment, high cyclohexanone conversion rate, and stable acoustic field. By combining the heat energy generation unit and the heat energy consumption unit, the steam consumption of the equipment can be significantly reduced, the circulating water consumption can be reduced, and the production cost of caprolactam can be reduced.

[0025] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including combining the various technical features in any other way. These simple modifications and combinations should also be considered as the content disclosed by the present invention and all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be determined by the appended claims.

Claims

1. A high-temperature ammonium oxime reaction heat utilization system, characterized in that: It includes an ammonium oximation reactor and an evaporation tower. The reactor is equipped with a circulation pipeline and a circulation pump at the bottom. The evaporation tower is equipped with an evaporation tower reboiler. The outlet of the circulation pump is connected to the inlet of the evaporation tower reboiler. The outlet of the evaporation tower reboiler is connected to the return port of the ammonium oximation reactor after passing through a condenser. The top of the evaporation tower is equipped with a steam outlet, which is connected to the gas supply pipeline.

2. The system according to claim 1, characterized in that: The reboiler of the evaporator is located on the inner side of the lower part of the evaporator.

3. The system according to claim 2, characterized in that: The reboiler of the evaporator is a U-shaped tube type, and the liquid circulating from the ammonia oxime reaction vessel passes through the shell side of the evaporator reboiler for heat exchange.

4. The system according to claim 1, characterized in that: The evaporation tower is a packed tower.

5. The system according to any one of claims 1 to 4, characterized in that: Gas pipelines include users of the deammoniation tower, users of the caprolactam unit, and / or users of the ammonium sulfate unit.

6. The system according to claim 5, characterized in that: The user has a deammoniation tower, which is equipped with a deammoniation tower reboiler. The bottom outlet of the deammoniation tower is connected to the deammoniation tower reboiler through a pipeline and pump, and then returns to the deammoniation tower inlet.

7. The system according to claim 6, characterized in that: The steam pipe from the evaporator exchanges heat with the reboiler of the deammoniation tower and then connects to the condensate collection tank.

8. The system according to claim 6, characterized in that: The ammonia removal tower is a packed tower.

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