Separation system of acetonitrile and water azeotrope
By using chloroform as an azeotropic distillation system in a micro positive pressure azeotropic distillation system, combined with the design of distillation tower, reboiler and decanter, the separation of azeotropic substances of acetonitrile and water and the recycling of chloroform are achieved, which solves the problems of high equipment costs and high risk in the prior art, meets the requirements of continuous, automated and unmanned production equipment, and reduces energy consumption.
Patent Information
- Application Number
- CN202421909245.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-08
- Publication Date
- 2025-06-24
- Estimated Expiration
- 2034-08-08
AI Technical Summary
It is difficult to achieve continuous distillation separation of azeotropes of acetonitrile and water in the prior art, and the existing transformer distillation equipment is costly and at high risk, making it difficult to meet the continuous, automated and unmanned requirements of production equipment.
Chloroform is used as the azeotrope. In the micro-positive pressure azeotrope distillation system, the azeotrope separation of acetonitrile and water is achieved through the combination of a distillation tower and a reboiler. The azeotrope is separated by liquid-liquid layering technology, and the chloroform is further recovered through the decanter and the gas-liquid separation tank, reducing equipment investment and danger.
The continuous distillation separation of acetonitrile and water azeotropes is achieved, which reduces equipment investment and danger, meets the continuous, automated and unmanned requirements of production equipment, and reduces energy consumption through waste heat recovery.
Smart Images
Figure CN223009841U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of rectification separation, and particularly relates to a separation system for acetonitrile and water azeotrope. Background Art
[0002] Acetonitrile is a colorless liquid, highly volatile, and has good solubility in oils, inorganic salts, organic compounds, and high molecular compounds. As a solvent in the production of fluorinated ethylene carbonate from chloroethylene carbonate, acetonitrile can dissolve inorganic salt potassium fluoride and organic catalyst well, which is beneficial to the effective replacement fluorination reaction.
[0003] As a solvent used in the production device, acetonitrile needs to be recycled. The water contained in the recycled acetonitrile solvent will react with potassium fluoride to form hydrofluoric acid, corrode the equipment, and the replacement fluorination reaction cannot be carried out. Therefore, for a production device using acetonitrile as a solvent, it is necessary to dehydrate the recycled acetonitrile.
[0004] The azeotrope of acetonitrile and water cannot be separated by conventional rectification. Adding salts and ionic liquids to break the azeotrope in the prior art is difficult to achieve continuous rectification production in the production device, which is not conducive to the continuous, automated, and unmanned operation of the production device. Separating the acetonitrile and water azeotrope by pressure swing rectification with prior pressurization and subsequent depressurization can achieve continuous rectification of the device, but the pressure swing rectification equipment has high costs and high risk factors. The operating pressure of the rectification column in pressure swing rectification is high, and the rectification column equipment and internals need to be strengthened to meet the requirements of the pressure vessel equipment specification standards. The equipment investment and later maintenance and repair costs are high; for the downstream auxiliary facilities of the key supervised and dangerous chemical process (fluorination process), the pressurization equipment of acetonitrile solvent (class B flammable liquid) has a high risk factor, and safety and supervision measures need to meet the requirements of national regulations and specification standards.
[0005] In summary, there is an urgent need to provide a separation system that can continuously rectify and separate the acetonitrile and water azeotrope and is safe and low-cost. Summary of the Utility Model
[0006] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide a separation system for acetonitrile and water azeotrope, which performs azeotropic rectification separation on the acetonitrile and water azeotrope, selects chloroform as the azeotropic agent, and realizes the separation of the acetonitrile and water azeotrope under slightly positive pressure azeotropic rectification, which can not only meet the requirements of continuous, automated, and unmanned operation of the production device, but also reduce equipment investment and lower the risk.
[0007] The technical solution of the utility model is as follows:
[0008] A separation system for an acetonitrile and water azeotrope, comprising a distillation column. The distillation column is connected with an azeotrope feed pipeline, a top product discharge pipeline and a bottom product discharge pipeline. The bottom product discharge pipeline is connected with a reboiler, and the reboiler is connected with the distillation column through a pipeline; the top product discharge pipeline is connected with a top condenser, the top condenser is connected with a decanter through a pipeline, the decanter is connected with the reflux port of the distillation column through an organic phase discharge pipeline, and the reflux port of the distillation column is also connected with a chloroform supply pipeline. The decanter is connected with an aqueous phase preheater through an aqueous phase discharge pipeline, and the aqueous phase preheater is connected with the feed port of a gas-liquid separation tank through a pipeline; the gas-liquid separation tank is connected with a waste water discharge pipeline and a gas phase discharge pipeline, and the gas phase discharge pipeline is connected with the top condenser; an inlet preheater is connected to the azeotrope feed pipeline, the reboiler is connected with the aqueous phase preheater through a hot acetonitrile product feed pipeline, the aqueous phase preheater is connected with the inlet preheater through a hot acetonitrile product discharge pipeline, and the inlet preheater is connected with an acetonitrile product pipeline.
[0009] Preferably, the number of theoretical plates of the distillation column is 25, and the azeotrope feed pipeline is connected to the 12th plate position of the distillation column.
[0010] Preferably, the chloroform supply pipeline and the organic phase discharge pipeline of the decanter are connected to the 1st plate position of the distillation column.
[0011] Preferably, the chloroform supply pipeline is connected to the organic phase discharge pipeline.
[0012] Preferably, a reflux pump is connected to the organic phase discharge pipeline.
[0013] Preferably, the waste water discharge pipeline is connected to the bottom of the gas-liquid separation tank, and the gas phase discharge pipeline is connected to the top of the gas-liquid separation tank.
[0014] Compared with the prior art, the utility model has the following beneficial effects:
[0015] The separation system of the present utility model performs azeotropic distillation separation on the azeotrope of acetonitrile and water. Chloroform is selected as the azeotropic agent. Under the slightly positive pressure of 0.01 MPa(G) in the distillation column, the azeotropic temperature of water and chloroform is 58.87 °C, the boiling point temperature of chloroform is 64.09 °C, the boiling point temperature of acetonitrile is 84.72 °C, and the boiling point temperature of water is 102.75 °C. Moreover, the liquid phase of water and chloroform is heterogeneous, and liquid-liquid separation can be used for separation. Therefore, the present utility model performs azeotropic distillation separation on the azeotrope of acetonitrile and water, selects chloroform as the azeotropic agent, and the azeotrope of water and chloroform can be obtained at the top of the distillation column, reducing the energy consumption of the distillation column. The liquid phase of water and chloroform is heterogeneous, which is conducive to the separation and recovery of the azeotropic agent, and high-purity acetonitrile products can be obtained at the bottom of the distillation column. The water phase of the decanter goes to the gas-liquid separation tank to further recover chloroform for recycling, reducing the equipment investment of the azeotropic agent recovery column. At the same time, the hot acetonitrile product at the bottom of the distillation column first preheats the water phase and then preheats the azeotrope of acetonitrile and water, realizing the recovery of waste heat and reducing the energy consumption. The present utility model realizes the separation of the azeotrope of acetonitrile and water under slightly positive pressure azeotropic distillation, which can not only meet the requirements of continuous, automated, and unmanned production devices, but also reduce equipment investment and reduce risks. Brief Description of the Drawings
[0016] Figure 1 It is a schematic structural diagram of the separation system of the azeotrope of acetonitrile and water of the present utility model.
[0017] Figure 2 It is the temperature distribution diagram of the distillation column trays in Example 1.
[0018] Figure 3 It is the composition distribution diagram of the distillation column trays in Example 1.
[0019] In the figure, 1. Distillation column; 101. Azeotrope feed pipeline; 102. Top product pipeline; 103. Bottom product pipeline; 104. Chloroform supplement pipeline; 2. Reboiler; 3. Top condenser; 4. Decanter; 401. Organic phase product pipeline; 402. Water phase product pipeline; 5. Water phase preheater; 501. Hot acetonitrile product feed pipeline; 502. Hot acetonitrile product discharge pipeline; 6. Gas-liquid separation tank; 601. Waste water discharge pipeline; 602. Gas phase discharge pipeline; 7. Feed preheater; 701. Acetonitrile product pipeline; 8. Reflux pump. Detailed Embodiments
[0020] In order to enable those skilled in the art to better understand the technical solutions in the present utility model, the technical solutions of the present utility model will be clearly and completely described below in conjunction with the embodiments of the present utility model.
[0021] Example 1
[0022] As Figure 1As shown in the figure, this embodiment provides a separation system for acetonitrile and water azeotrope, which includes a distillation column 1. The distillation column 1 is connected with an azeotrope feed pipeline 101, a top product discharge pipeline 102 and a bottom product discharge pipeline 103. The bottom product discharge pipeline 103 is connected with a reboiler 2, and the reboiler 2 is connected with the distillation column 1 through a pipeline; the top product discharge pipeline 102 is connected with a top condenser 3, the top condenser 3 is connected with a decanter 4 through a pipeline, the decanter 4 is connected with the reflux port of the distillation column 1 through an organic phase discharge pipeline 401, and a chloroform supplement pipeline 104 is also connected to the organic phase discharge pipeline 401. A reflux pump 8 is connected to the organic phase discharge pipeline 401; the decanter 4 is connected with a water phase preheater 5 through a water phase discharge pipeline 402, and the water phase preheater 5 is connected with the feed port of a gas-liquid separation tank 6 through a pipeline; the bottom of the gas-liquid separation tank 6 is connected with a waste water discharge pipeline 601, and the top is connected with a gas phase discharge pipeline 602. The gas phase discharge pipeline 602 is connected with the top condenser 3; a feed preheater 7 is connected to the azeotrope feed pipeline 101. The reboiler 2 is connected with the water phase preheater 5 through a hot acetonitrile product feed pipeline 501, the water phase preheater 5 is connected with the feed preheater 7 through a hot acetonitrile product discharge pipeline 502, and the feed preheater 7 is connected with an acetonitrile product pipeline 701.
[0023] Working principle:
[0024] The flow rate of the azeotrope feed pipeline 101 of the distillation column 1 is 5000 kg / h, the temperature is 25 °C, the pressure is 0.20 MPa (G), and the composition is 81.9 wt.% acetonitrile and 18.1 wt.% water; the flow rate of the chloroform supplement pipeline 104 is 2.15 kg / h, the temperature is 25 °C, the pressure is 0.10 MPa (G), and the composition is 100 wt.% chloroform.
[0025] The number of theoretical plates of the distillation column 1 is 25, the top pressure is 0.01 MPa (G), and the tray pressure drop is 0.1 psi. After the azeotrope feed pipeline 101 is heated to 50 °C by the heat recovered from the hot acetonitrile product in the feed preheater 7, it enters the 12th tray position of the distillation column 1. High-purity hot acetonitrile product at 88.91 °C (as Figure 2 shown) is obtained at the bottom of the distillation column 1. This part of the hot acetonitrile product first enters the water phase preheater 5 to preheat the water phase separated by the decanter 4, and then enters the feed preheater 7 to preheat the acetonitrile and water azeotrope, realizing the waste heat recovery of the hot acetonitrile product.
[0026] An azeotrope of chloroform and water is obtained at the top of the distillation column 1. After being condensed by the top condenser 3, it undergoes liquid-liquid phase equilibrium in the decanter 4 to obtain an organic phase (chloroform content 99.71 wt.%) and an aqueous phase (water content 99.28 wt.%). The aqueous phase of the decanter 4 is heated to 80°C by the heat recovered from the hot acetonitrile product in the aqueous phase preheater 5 and then enters the gas-liquid separation tank 6. The gas phase at the top of the gas-liquid separation tank 6 (chloroform content 87.93 wt.%) is condensed by the top condenser 3 and recycled to the decanter 4, and high-purity wastewater is obtained at the bottom of the tank.
[0027] After the chloroform makeup pipeline 104 is mixed with the organic phase discharge pipeline 401 of the decanter 4, it is pressurized by the reflux pump 8 and enters the first plate position of the distillation column 1.
[0028] Using the aspen plus software and selecting the NRTL physical property method, the vapor-liquid-liquid ternary phase equilibrium of acetonitrile, water, and chloroform is simulated and calculated. The flow rate of the hot acetonitrile product feed pipeline 501 is 4095 kg / h, the temperature is 88.91°C (as Figure 2 shown), the pressure is 0.03 MPa(G), and the composition is 99.9916 wt.% acetonitrile, 0.0001 wt.% water, 0.0083 wt.% chloroform (as Figure 3 shown); the flow rate of the acetonitrile product pipeline 701 after heat recovery treatment is 4095 kg / h, the temperature is 48.43°C, the pressure is 0.03 MPa(G), and the composition is 99.9916 wt.% acetonitrile, 0.0001 wt.% water, 0.0083 wt.% chloroform.
[0029] The flow rate of the wastewater discharge pipeline 601 at the bottom of the gas-liquid separation tank 6 is 907.15 kg / h, the temperature is 80°C, the pressure is 0 MPa(G), and the composition is 99.7625 wt.% water, 0.0380 wt.% acetonitrile, 0.1995 wt.% chloroform.
[0030] The heat load of the reboiler 2 is 3691.94 kW.
[0031] Comparative Example 1
[0032] The difference from Example 1 is that the azeotrope feed pipeline 101 is connected to the tenth plate position of the distillation column 1.
[0033] The flow rate of the hot acetonitrile product feed pipeline 501 finally obtained in Comparative Example 1 is 4095 kg / h, the temperature is 88.91°C, the pressure is 0.03 MPa(G), and the composition is 99.9849 wt.% acetonitrile, 0.0151 wt.% chloroform; the flow rate of the wastewater discharge pipeline 601 at the bottom of the gas-liquid separation tank 6 is 907.43 kg / h, the temperature is 80°C, the pressure is 0 MPa(G), and the composition is 99.7323 wt.% water, 0.0683 wt.% acetonitrile, 0.1994 wt.% chloroform.
[0034] Comparative Example 2
[0035] The difference from Example 1 is that the azeotrope feed line 101 is connected to the 11th plate position of the distillation column 1.
[0036] The flow rate of the hot acetonitrile product feed line 501 finally obtained in Comparative Example 1 is 4095 kg / h, the temperature is 88.91 °C, the pressure is 0.03 MPa(G), and the composition is 99.9890 wt.% acetonitrile, 0.0001 wt.% water, 0.0109 wt.% chloroform; the flow rate of the waste water discharge line 601 at the bottom of the gas-liquid separation tank 6 is 907.26 kg / h, the temperature is 80 °C, the pressure is 0 MPa(G), and the composition is 99.7511 wt.% water, 0.0495 wt.% acetonitrile, 0.1994 wt.% chloroform.
[0037] Comparative Example 3
[0038] The difference from Example 1 is that the azeotrope feed line 101 is connected to the 13th plate position of the distillation column 1.
[0039] The flow rate of the hot acetonitrile product feed line 501 finally obtained in Comparative Example 3 is 4095 kg / h, the temperature is 88.91 °C, the pressure is 0.03 MPa(G), and the composition is 99.9932 wt.% acetonitrile, 0.0004 wt.% water, 0.0064 wt.% chloroform; the flow rate of the waste water discharge line 601 at the bottom of the gas-liquid separation tank 6 is 907.07 kg / h, the temperature is 80 °C, the pressure is 0 MPa(G), and the composition is 99.7698 wt.% water, 0.0307 wt.% acetonitrile, 0.1995 wt.% chloroform. The heat load of the reboiler 2 is 3701.84 kW.
[0040] Comparative Example 4
[0041] The difference from Example 1 is that the azeotrope feed line 101 is connected to the 14th plate position of the distillation column 1.
[0042] The flow rate of the hot acetonitrile product feed line 501 finally obtained in Comparative Example 4 is 4095 kg / h, the temperature is 88.91 °C, the pressure is 0.03 MPa(G), 99.9941 wt.% acetonitrile, 0.0012 wt.% water, 0.0047 wt.% chloroform; the flow rate of the waste water discharge line 601 at the bottom of the gas-liquid separation tank 6 is 907.00 kg / h, the temperature is 80 °C, the pressure is 0 MPa(G), and the composition is 99.7741 wt.% water, 0.0264 wt.% acetonitrile, 0.1995 wt.% chloroform. The heat load of the reboiler 2 is 3752.91 kW.
[0043] It can be seen from the comparison between Example 1 and Comparative Examples 1-4 that the lower the connection position of the azeotrope feed pipeline 101 to the plate of the distillation column 1, the higher the purity of the final acetonitrile product obtained. However, the heat load will also be higher. Therefore, considering these two factors comprehensively, when the azeotrope feed pipeline 101 is connected to the 12th plate of the distillation column 1, the requirements of high product purity and low heat load can be balanced, and the effect is optimal.
Claims
1. A separation system for acetonitrile and water azeotrope, characterized in that: The invention comprises a distillation tower (1), wherein the distillation tower (1) is connected to an azeotropic feed pipeline (101), a tower top discharge pipeline (102) and a tower bottom discharge pipeline (103), wherein the tower bottom discharge pipeline (103) is connected to a reboiler (2), and the reboiler (2) is connected to the distillation tower (1) through a pipeline; the tower top discharge pipeline (102) is connected to a tower top condenser (3), and the tower top condenser (3) is connected to a decanter (4) through a pipeline, and the decanter (4) is connected to the reflux port of the distillation tower (1) through an organic phase discharge pipeline (401), and the reflux port of the distillation tower (1) is also connected to a chloroform supplement pipeline (104), and the decanter (4) is connected to the reflux port of the distillation tower (1) through an aqueous phase discharge pipeline (40 2) is connected to a water phase preheater (5), and the water phase preheater (5) is connected to the feed port of a gas-liquid separation tank (6) through a pipeline; the gas-liquid separation tank (6) is connected to a wastewater discharge pipeline (601) and a gas phase discharge pipeline (602), and the gas phase discharge pipeline (602) is connected to a tower top condenser (3); the azeotropic feed pipeline (101) is connected to a feed preheater (7), the reboiler (2) is connected to the water phase preheater (5) through a hot acetonitrile product feed pipeline (501), the water phase preheater (5) is connected to the feed preheater (7) through a hot acetonitrile product discharge pipeline (502), and the feed preheater (7) is connected to an acetonitrile product pipeline (701).
2. The separation system of acetonitrile and water azeotrope as claimed in claim 1, characterized in that The number of theoretical plates of the distillation tower (1) is 25, and the azeotrope feed pipeline (101) is connected to the 12th plate position of the distillation tower (1).
3. The separation system of acetonitrile and water azeotrope as claimed in claim 1, characterized in that The chloroform replenishment pipeline (104) is connected to the organic phase discharge pipeline (401) of the decanter (4) at the first plate position of the distillation tower (1).
4. The separation system of acetonitrile and water azeotrope as claimed in claim 1, characterized in that The chloroform replenishment pipeline (104) is connected to the organic phase discharge pipeline (401).
5. The separation system of acetonitrile and water azeotrope as claimed in claim 4, characterized in that The organic phase discharge pipeline (401) is connected to a reflux pump (8).
6. The separation system of acetonitrile and water azeotrope as claimed in claim 1, characterized in that The wastewater discharge pipeline (601) is connected to the bottom of the gas-liquid separation tank (6), and the gas phase discharge pipeline (602) is connected to the top of the gas-liquid separation tank (6).