Device for recovering trifluoroacetic acid from kettle residues of rectifying tower

Abstract

The utility model belongs to the technical field of rectifying tower recovery devices, and particularly relates to a device for recovering trifluoroacetic acid from rectifying tower residues. The device comprises a negative pressure evaporator, a condenser, a negative pressure buffer tank, a recovery circulating tank, a heat exchanger and a vacuum unit, the recovery circulating tank is connected with the negative pressure evaporator through a circulating pump, an outlet of the negative pressure evaporator is connected with the heat exchanger through a pipeline, and the vacuum unit is connected with the condenser. An outlet of the negative pressure evaporator is connected with a heat exchanger, an outlet of the heat exchanger is connected with a recycling and circulating tank to realize recycling of materials, a gas phase outlet of the negative pressure evaporator is connected with a condenser, a condensate outlet of the condenser is connected to a material receiving tank to collect trifluoroacetic acid, and an uncondensed gas outlet of the condenser is connected with a negative pressure buffer tank to maintain a negative pressure state of the system. The device for recovering trifluoroacetic acid from the kettle residues of the rectifying tower provided by the utility model is low in energy consumption, reduces the discharge of hazardous wastes, reduces the cost and improves the income.

Description

Technical Field

[0001] The utility model belongs to the technical field of rectification column recovery devices, and particularly relates to a device for recovering trifluoroacetic acid from the residue at the bottom of a rectification column kettle. Background Technique

[0002] In the chemical industry, trifluoroacetic acid, as an important organic synthesis intermediate, is widely used in multiple industries such as pharmaceuticals, pesticides, dyes, and new materials. Currently, the oxidation method of trifluorotrichloroethane is one of the mainstream processes for producing trifluoroacetic acid. Its production process involves complex chemical reactions and separation and purification steps. Specifically, after a series of chemical reactions generate trifluoroacetic acid, it needs to be treated in a de-light tower to remove light components, and then enters a trifluoroacetic acid rectification column for deep purification. During this process, trifluoroacetic acid products meeting quality standards can be taken out from the top of the rectification column, while the bottom of the column is enriched with unreacted raw materials, by-products, and catalysts (such as sulfuric acid), etc.

[0003] However, with the extension of the production cycle, the concentration of sulfuric acid in the bottom of the column gradually accumulates to about 30%, which significantly affects the separation efficiency and product purity of the rectification process. High-concentration sulfuric acid not only intensifies the interaction between materials in the column but also promotes the occurrence of side reactions, resulting in a sharp increase in the impurity content in the top product, making it unable to meet the product quality requirements, and thus causing a decline in the yield of qualified products. In addition, if the bottom materials rich in sulfuric acid continue to circulate in the system, the production situation will be further deteriorated, increasing energy consumption and operation difficulty.

[0004] In view of this, currently in industrial practice, the common method is to press out such bottom materials with high sulfuric acid content from the system and entrust external professional institutions for treatment. However, this method has significant drawbacks: on the one hand, about 70% of trifluoroacetic acid is lost due to ineffective recovery, directly increasing the unit consumption cost of the device; on the other hand, the generation of a large amount of sulfuric acid-containing hazardous waste not only increases the environmental protection pressure on enterprises but also increases the overall operation cost due to the high cost of outsourcing treatment. Therefore, developing an efficient and environmentally friendly technology for treating and recovering the bottom materials of trifluoroacetic acid production towers to effectively separate sulfuric acid and efficiently recover trifluoroacetic acid has become an urgent technical problem to be solved. Content of the Utility Model

[0005] The technical problem to be solved by the utility model is to overcome the above-mentioned defects existing in the prior art, and provide a device for recovering trifluoroacetic acid from the residue at the bottom of a rectification column kettle, which has low energy consumption, reduces the emission of hazardous waste, reduces costs, and increases benefits.

[0006] Device for recovering trifluoroacetic acid from residue in rectifying column kettle of the utility model: It includes a negative pressure evaporator, a condenser, a negative pressure buffer tank, a recovery circulation tank, a heat exchanger, and a vacuum unit. The recovery circulation tank is connected to the negative pressure evaporator through a circulation pump to form a circulation loop. The outlet of the negative pressure evaporator is connected to the heat exchanger through a pipeline for heat exchange. The outlet of the heat exchanger is then connected to the recovery circulation tank to realize the recirculation of materials. The gas phase outlet of the negative pressure evaporator is connected to the condenser. The condensate outlet of the condenser is connected to a receiving tank to collect trifluoroacetic acid. At the same time, the non-condensable gas outlet of the condenser is connected to the negative pressure buffer tank to maintain the negative pressure state of the system.

[0007] Preferably, a steam heater is provided on the negative pressure evaporator to provide heat energy for the negative pressure evaporator to promote the evaporation of trifluoroacetic acid.

[0008] Preferably, a gas phase port is provided on the negative pressure evaporator and is connected to the inlet of the condenser through the gas phase port to ensure that the evaporated trifluoroacetic acid gas can efficiently enter the condenser for condensation.

[0009] Preferably, a liquid phase port is provided on the negative pressure evaporator. The liquid phase port is connected to the inlet of the heat exchanger through a pipeline to realize the heat exchange and recirculation of the unevaporated liquid material in the evaporator.

[0010] Preferably, a feed pipe is provided on the recovery circulation tank for introducing the trifluoroacetic acid solution to be recovered into the recovery circulation tank.

[0011] Preferably, the negative pressure buffer tank is directly connected to the vacuum unit, and the vacuum unit provides a negative pressure environment for the whole system to promote the evaporation and subsequent treatment of trifluoroacetic acid.

[0012] Preferably, the condenser is cooled by an efficient cooling medium to improve the condensation efficiency of trifluoroacetic acid.

[0013] When the device for recovering trifluoroacetic acid from the residue in the rectifying column kettle of the utility model is working, the vacuum unit is started to form a negative pressure system. The negative pressure buffer tank is used for negative pressure buffering and pumping negative pressure. The negative pressure is controlled at -5 to -50 KPa. The material (about 30% sulfuric acid) pressed out from the rectifying column kettle enters the recovery circulation tank through the feed pipe, is pumped up by the circulation pump and enters the negative pressure evaporator with the flow rate controlled. The liquid phase discharges from the bottom of the negative pressure evaporator, enters the heat exchanger and then enters the recovery circulation tank for circulation. The steam heater of the negative pressure evaporator is started to heat the circulating material, and the heating temperature is controlled at 90 - 130 °C. The gaseous trifluoroacetic acid and water enter the condenser from the gas phase port of the negative pressure evaporator for condensation. The liquid-phase trifluoroacetic acid enters the receiving tank to collect trifluoroacetic acid, and the recovery is completed. As the concentration of sulfuric acid increases and trifluoroacetic acid cannot be recovered, the steam is stopped, and the material is pressed out of the system and entrusted to an external processing company in a ton barrel.

[0014] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0015] (1) The device for recovering trifluoroacetic acid from the residue in the bottom of the distillation column of the present utility model, compared with the traditional distillation device, adopts vacuum distillation to reduce the operating temperature, and solves the problems of difficult equipment selection and high operating difficulty due to high boiling point.

[0016] (2) The device for recovering trifluoroacetic acid from the residue in the bottom of the distillation column of the present utility model conducts secondary recovery of the residue in the bottom of the distillation column, reducing the production unit consumption.

[0017] (3) The device for recovering trifluoroacetic acid from the residue in the bottom of the distillation column of the present utility model reduces the generation amount of hazardous waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The figure is a schematic diagram of the device for recovering trifluoroacetic acid from the residue in the bottom of the distillation column of the present utility model.

[0019] In the figure: 1, vacuum evaporator; 2, condenser; 3, vacuum buffer tank; 4, recovery circulation tank; 5, heat exchanger; 6, receiving tank; 7, vacuum unit; 8, steam heater; 9, circulation pump; 10, feed pipe; 11, liquid phase port; 12, gas phase port. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The present utility model will be further described below in conjunction with specific embodiments.

[0021] As Figure 1 shown, the device for recovering trifluoroacetic acid from the residue in the bottom of the distillation column: includes a vacuum evaporator 1, a condenser 2, a vacuum buffer tank 3, a recovery circulation tank 4, a heat exchanger 5, and a vacuum unit 7. The recovery circulation tank 4 is connected to the vacuum evaporator 1 through a circulation pump 9 to form a circulation loop. The outlet of the vacuum evaporator 1 is connected to the heat exchanger 5 through a pipeline for heat exchange. The outlet of the heat exchanger 5 is then connected to the recovery circulation tank 4 to realize the recycling of materials. The gas phase outlet of the vacuum evaporator 1 is connected to the condenser 2. The condensate outlet of the condenser 2 is connected to the receiving tank 6 to collect trifluoroacetic acid. At the same time, the non-condensable gas outlet of the condenser 2 is connected to the vacuum buffer tank 3 to maintain the negative pressure state of the system.

[0022] Preferably, a steam heater 8 is provided on the vacuum evaporator 1. It is used to provide heat energy for the vacuum evaporator 1 to promote the evaporation of trifluoroacetic acid.

[0023] Preferably, a gas phase port 12 is provided on the vacuum evaporator 1. It is connected to the inlet of the condenser 2 through the gas phase port 12 to ensure that the evaporated trifluoroacetic acid gas can efficiently enter the condenser for condensation.

[0024] Preferably, a liquid phase port 11 is provided on the negative pressure evaporator 1. This liquid phase port 11 is connected to the inlet of the heat exchanger 5 through a pipeline to achieve heat exchange and recirculation of the unevaporated liquid material in the evaporator.

[0025] Preferably, a feed pipe 10 is provided on the recovery circulation tank 4 for introducing the trifluoroacetic acid solution to be recovered into the recovery circulation tank 4.

[0026] Preferably, the negative pressure buffer tank 3 is directly connected to the vacuum unit 7, and the vacuum unit 7 provides a negative pressure environment for the entire system to promote the evaporation and subsequent treatment of trifluoroacetic acid.

[0027] Preferably, the condenser 2 is cooled by an efficient cooling medium to improve the condensation efficiency of trifluoroacetic acid.

[0028] When the device for recovering trifluoroacetic acid from the residue at the bottom of the rectification tower kettle of the present utility model is working, the vacuum unit 7 is started to form a negative pressure system. The negative pressure buffer tank 3 is used for negative pressure buffering and negative pressure pumping. The negative pressure is controlled at -5 to -50 KPa. The material (about 30% sulfuric acid) discharged from the rectification tower kettle enters the recovery circulation tank 4 through the feed pipe 10, and is pumped by the circulation pump 9 to control the flow rate and enter the negative pressure evaporator 1. The liquid phase discharges from the bottom of the negative pressure evaporator 1, enters the heat exchanger 5 and then enters the recovery circulation tank 4 for circulation; the negative pressure evaporator 1 starts the steam heater 8 to heat the circulating material, and the heating temperature is controlled at 90 - 130 °C. The gaseous trifluoroacetic acid and water enter the condenser 2 from the gas phase port 12 of the negative pressure evaporator for condensation, and the liquid phase trifluoroacetic acid enters the receiving tank 6 to collect trifluoroacetic acid, completing the recovery. As the concentration of sulfuric acid increases and trifluoroacetic acid cannot be recovered effectively, stop the steam, and press the material outside the system into a ton barrel for external processing.

[0029] The device for recovering trifluoroacetic acid from the residue at the bottom of the rectification tower kettle provided by the present utility model realizes the efficient recovery of trifluoroacetic acid from the residue at the bottom of the rectification tower kettle by introducing a negative pressure evaporation device and a condensation recovery device. In a negative pressure environment of -5 kPa to -50 kPa, the material is heated to 90 °C to 130 °C by a steam heater, which effectively promotes the evaporation and separation of trifluoroacetic acid and significantly improves the recovery rate. Compared with the traditional method of directly outsourcing for treatment, the method of the present utility model can recover about 70% of the trifluoroacetic acid that could not be reused originally, which not only reduces resource waste, but also significantly reduces the production cost and environmental protection pressure of the enterprise.

[0030] For the device for recovering trifluoroacetic acid from the residue at the bottom of the rectification tower kettle proposed by the present utility model, as the concentration of sulfuric acid increases and trifluoroacetic acid cannot be effectively recovered continuously, the present utility model can timely stop the steam heating and safely press the remaining material out of the system for treatment, avoiding further erosion of the equipment by high-concentration sulfuric acid, and further ensuring production safety and environmental protection requirements.

[0031] Certainly, the above content is only a preferred embodiment of the present utility model and cannot be considered as limiting the scope of the embodiments of the present utility model. The present utility model is not limited to the above examples either. Equivalent changes and improvements made by those of ordinary skill in the art within the essence of the present utility model shall all fall within the scope covered by the patent of the present utility model.

Claims

1. A device for recovering trifluoroacetic acid from the still residue of a distillation tower, characterized in that: The invention comprises a negative pressure evaporator (1), a condenser (2), a negative pressure buffer tank (3), a recovery circulation tank (4), a heat exchanger (5), and a vacuum unit (7). The recovery circulation tank (4) is connected to the negative pressure evaporator (1) via a circulation pump (9), the negative pressure evaporator (1) is connected to the heat exchanger (5), the heat exchanger (5) is connected to the recovery circulation tank (4), the negative pressure evaporator (1) is connected to the condenser (2), the condenser (2) is connected to a material receiving tank (6), and the condenser (2) is connected to the negative pressure buffer tank (3).

2. The device for recovering trifluoroacetic acid from the still residue of the rectifying tower according to claim 1, characterized in that: The negative pressure evaporator (1) is provided with a steam heater (8).

3. The device for recovering trifluoroacetic acid from the still residue of the rectifying tower according to claim 1, characterized in that: The negative pressure evaporator (1) is provided with a gas phase port (12).

4. The device for recovering trifluoroacetic acid from the still residue of a rectifying tower according to claim 1, characterized in that: The negative pressure evaporator (1) is provided with a liquid phase port (11).

5. The device for recovering trifluoroacetic acid from the still residue of the rectifying tower according to claim 1, characterized in that: The recovery circulation tank (4) is provided with a feed pipe (10).

6. The device for recovering trifluoroacetic acid from the still residue of a rectifying tower according to claim 1, characterized in that: The negative pressure buffer tank (3) is connected to the vacuum unit (7).

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