Separation device and separation method for mixed liquid of triethylamine, acetonitrile and water

Abstract

The invention relates to a separation device and a separation method of a mixed solution of acetonitrile, triethylamine and water, the separation method comprises the following steps: adding an entrainer into the mixed solution of acetonitrile, triethylamine and water, the entrainer being azeotropic with water; a first rectification step: carrying out rectification treatment by taking the mixed solution containing the entrainer as a first feed material, so that the entrainer and water are subjected to azeotropic distillation; separating the distillate obtained in the first rectification step to obtain water and an entrainer; a second rectification step: carrying out rectification treatment on the tower bottoms in the first rectification step to obtain separated acetonitrile and triethylamine; according to the separation method, high-cost equipment such as membrane separation is not needed for dehydration, so that the equipment investment cost is low, the whole process is relatively simple, and the separation cost is relatively low; the energy consumption of separation can be reduced and the separation efficiency can be improved; a heterogeneous azeotropic mode is adopted for dehydration, and an entrainer is simple in recovery mode and can be repeatedly utilized for multiple times; the dehydration effect is obvious, and the water content in the treated mixed liquid can be reduced to be less than 100ppm.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical separation and relates to a method and a device for separating a mixed liquid of triethylamine, acetonitrile and water. Background Art

[0002] Acetonitrile, triethylamine and water mixture is a common type of waste liquid in various chemical processes. Acetonitrile, also known as methyl nitrile, is an excellent polar aprotic solvent. It is miscible with water, methanol, carbon tetrachloride, methyl acetate, ethyl acetate, ethylene dichloride and many unsaturated hydrocarbon solvents. It is widely used in the petroleum industry, high-quality industry, medicine and fine chemicals. Triethylamine is a liquid at room temperature and is the simplest homotrisubstituted tertiary amine. It is often used as a solvent, catalyst or base in organic synthesis. The above two substances are often used as solvents in the fine chemical and pharmaceutical industries, so a large amount of acetonitrile, triethylamine and water waste liquid is often generated during the production process.

[0003] The separation of the above-mentioned mixed liquid is a difficult problem in the industry. Since acetonitrile and water are azeotropic (the azeotropic point is 76°C at normal pressure, and the water content is 16%), and triethylamine and water are also azeotropic (the azeotropic point is 75°C, and the water content is 10%), it is difficult to separate the mixed liquid of the three by ordinary distillation. Therefore, enterprises usually choose to hand over the waste liquid to environmental protection companies for treatment, which has high treatment costs.

[0004] The specific methods for separating and treating the mixture of acetonitrile, triethylamine and water are retrieved as follows: for example, patent CN113461571A discloses that the mixture is extracted and separated by liquid-liquid extraction with water, and then triethylamine, acetonitrile and water are separated by three-tower distillation; for example, patent CN113461544A discloses that acetonitrile, triethylamine and water are separated by three-tower distillation and liquid-liquid extraction using cyclohexane as an azeotropic agent; and patent CN115850091A performs two azeotropic distillations and uses a NaA molecular sieve membrane for dehydration.

[0005] The above-mentioned various process flows of the prior art are relatively complicated, involving numerous equipments, requiring large equipment investment and high separation cost. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a new separation method and device for a mixed solution of triethylamine, acetonitrile and water.

[0007] The method for separating a mixed liquid of triethylamine, acetonitrile and water comprises the following steps: a first distillation step, in which the mixed liquid and an azeotropic agent are used as feeds for distillation treatment, wherein the mixed liquid comprises acetonitrile, triethylamine and water, and the azeotropic agent can azeotropize with water; a separation step, in which the distillate of the first distillation step is separated to obtain water and the azeotropic agent; and a second distillation step, in which the bottom liquid of the first distillation step is distilled to obtain separated acetonitrile and triethylamine.

[0008] The above method realizes the separation of acetonitrile, triethylamine and water by two distillations. In the existing scheme, acetonitrile or triethylamine is usually first purified and separated from the system, and then dehydrated by membrane dehydration and other methods. The inventor proposes that for the unconventional distillation separation of the mixed liquid system of acetonitrile, triethylamine and water, dehydration is an important process. The present invention proposes for the first time to first perform a dehydration operation, use an azeotropic agent to take water out of the mixed liquid, and the tower bottom can obtain a mixed liquid of acetonitrile and triethylamine with extremely low water content (≤100ppm), which can be separated by ordinary distillation treatment to obtain acetonitrile and triethylamine with higher purity. This method does not require high-cost equipment such as membrane separation for dehydration, and the overall process flow is simple and low in cost.

[0009] Preferably, the entrainer is immiscible with water; the separation step is to separate water and the entrainer by extraction. The entrainer can be heterogeneously azeotropic with water, and after distillation, the water and the entrainer in the distillate can be separated by liquid-liquid phase separation, and the entrainer can be easily recovered.

[0010] Preferably, an extraction step is further included before the first distillation step, in which the mixed liquid and the azeotropic agent are subjected to extraction treatment, and the extracted oil phase is used as feed for the first distillation step.

[0011] Preferably, the water content in the mixed liquid is ≥5%wt. For a mixed liquid with a high water content (weight fraction ≥5%), direct azeotropic distillation has a high dehydration pressure. The preferred method utilizes the immiscible characteristics of the azeotropic agent and water to first perform liquid-liquid extraction on acetonitrile and triethylamine in the mixed liquid. In addition to the advantages of simplifying the distillation process and reducing separation energy consumption brought by conventional heterogeneous azeotropy in the first distillation step, the extraction technology can also be combined to remove most of the water first, reducing the pressure of subsequent azeotropic dehydration.

[0012] Preferably, the azeotropic agent is dichloromethane, chloroform or isoprene.

[0013] Preferably, the separation method further comprises recovering the azeotropic agent obtained in the separation step and providing it to the first distillation step for further distillation treatment.

[0014] Preferably, the separation method further comprises recovering the azeotropic agent obtained in the separation step and providing it to the extraction step for extraction treatment.

[0015] Preferably, the mass ratio of the mixed liquid to the entrainer in the extraction step is 1:1.5-1:3.

[0016] The device for separating a mixed liquid of acetonitrile, triethylamine and water provided by the present invention comprises a first distillation unit, a separation unit and a second distillation unit; the feed of the first distillation unit comprises a mixed liquid and an entrainer, the mixed liquid comprises acetonitrile, triethylamine and water, and the entrainer can azeotropize with water; the distillate of the first distillation unit comprises an azeotrope of the entrainer and water, and the bottom liquid comprises acetonitrile and triethylamine; the separation unit and the second distillation unit respectively receive the distillate of the first distillation unit and the bottom liquid and separate them.

[0017] Preferably, the azeotropic agent is immiscible with water, and an extraction unit is provided before the first distillation unit to extract the mixed liquid and the azeotropic agent; the oil phase outlet of the extraction unit is connected to the feed port of the first distillation unit.

[0018] The invention proposes that dehydration treatment is the key to the rectification separation of a mixed liquid system of acetonitrile, triethylamine and water, and based on this, a new separation method is proposed. The method adopts a heterogeneous azeotropic dehydration method, and is combined with an extraction dehydration method for pretreatment, so that the water content in the mixed liquid can be reduced first, and the pressure of subsequent dehydration is reduced, which is beneficial to reducing the energy consumption of separation and improving the separation efficiency; the overall process flow does not require high-cost equipment such as membrane separation for dehydration, so that the equipment investment cost is low and the separation cost is low; the heterogeneous azeotropic dehydration method has a simple entrainer recovery method and can be repeatedly used; the dehydration effect is obvious, and the water content in the mixed liquid after treatment can be reduced to less than 100 ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a principle block diagram of an embodiment; Figure 2 It is a functional block diagram of another embodiment. DETAILED DESCRIPTION

[0020] In order to allow readers to more intuitively understand certain specific implementation methods of the present application, the present application also provides the following examples for readers' reference.

[0021] like Figure 1 As shown, the separation device of the mixed solution of acetonitrile, triethylamine and water of the present invention comprises a first distillation unit, a second distillation unit and a separation unit; The first distillation unit has a first feed port for inputting a mixed liquid of acetonitrile, triethylamine and water, and a second feed port for inputting an azeotropic agent, wherein the first feed port and the second feed port may be two separate feed ports or a combined feed port; The top extraction end of the first distillation unit is connected to the feed end of the separation unit, and the separation unit separates the top distillate of the first distillation unit. The first discharge end of the separation unit is a water phase discharge end to output most of the water, and the second discharge end of the separation unit is an oil phase discharge end to output most of the entrainer. The first branch of the oil phase discharge end is connected to the reflux port of the first distillation unit, and the second branch of the oil phase discharge end extracts the recovered entrainer, which can be recycled and reused, that is, the separated entrainer is recycled and provided to the first distillation unit for further distillation; The bottom extraction end of the first distillation unit is connected to the feed end of the second distillation unit. The second distillation unit distills the bottom liquid of the first distillation unit, and acetonitrile is extracted from the top fraction of the second distillation unit, and triethylamine is extracted from the bottom of the second distillation unit.

[0022] The first distillation unit can be an azeotropic distillation tower, and the second distillation unit can be an atmospheric distillation tower; the separation unit is a layered tank; the first distillation unit includes a distillation tower with 30-45 theoretical plates, and the first feed port is set at the 15th-20th plate; the second distillation unit includes a distillation tower with 40-60 theoretical plates, and the feed end is set at the 20th-30th plate.

[0023] Use as Figure 1 The method for separating the mixed liquid by the separation device shown is as follows: in the first distillation step, the mixed liquid containing the entrainer (i.e., the mixed liquid of acetonitrile, triethylamine and water) is used as the first feed for distillation treatment, that is, the entrainer and the mixed liquid are input into the first distillation unit, or the entrainer and the mixed liquid are respectively input into the first distillation unit, so that the entrainer and water are azeotropically distilled in the first distillation unit; the distillate of the first distillation step is passed into the separation unit for separation, and water and the entrainer are separated; in the second distillation step, the bottom liquid of the first distillation step is passed into the second distillation unit for distillation treatment, and separated acetonitrile and triethylamine are obtained.

[0024] Use the above Figure 1 Specific embodiments of the separation device and separation method (Example 1) In this embodiment, the mixture of acetonitrile, triethylamine and water comprises the following compositions and their mass fractions: 1% to 20% water, 70 to 85% acetonitrile, and 2 to 5% triethylamine. The mixture is treated by azeotropic distillation. The heterogeneous azeotropic agent is dichloromethane. The mixture and dichloromethane are pumped into the azeotropic distillation tower (first distillation unit) at a mass ratio of 1:1.5 to 1:3. The mixture is treated at a mass ratio of 1:1.5 in this embodiment. The raw material mixture is heated at 333 kg / min. h is pumped into the azeotropic distillation tower from the 15th plate, and dichloromethane is pumped into the azeotropic distillation tower from the 5th plate at 500kg / h. The theoretical number of plates of the distillation tower is 30. After full reflux until the top temperature is stable at 38°C and the bottom temperature is stable at 69°C, the top of the azeotropic distillation tower is produced to the stratification tank (separation unit) for stratification, and part of the oil phase is controlled to reflux, and the water phase is fully produced; the composition and mass fraction of the water phase produced from the top of the stratification tank are: 98.7% water, 1.3% dichloromethane, and the mass flow rate is 50kg / h. The composition and mass fraction of the reflux oil phase at the top of the stratification tank are: 0.2% water, 99.8% dichloromethane, and the mass flow rate is 4325kg / h. The composition and mass fraction of the oil phase produced from the top of the stratification tank are: 0.2% water, 99.8% dichloromethane, and the mass flow rate is 500kg / h, which is returned to the azeotropic distillation tower (first distillation unit) as a heterogeneous azeotropic agent. The azeotropic distillation tower bottom obtains a mixed liquid of acetonitrile and triethylamine with extremely low water content (water content ≤100ppm in the bottom liquid), whose composition and mass fraction are: acetonitrile 97.6%, triethylamine 2.4%, and mass flow rate 283kg / h. The bottom liquid of the azeotropic distillation tower is sent to the atmospheric distillation tower (the second distillation unit), and acetonitrile is produced from the top of the atmospheric distillation tower, and its composition and mass fraction are: acetonitrile 99.7%, triethylamine 0.3%, and mass flow rate 277kg / h. The triethylamine is produced from the bottom of the atmospheric distillation tower, and its composition and mass fraction are: triethylamine 99.4%, acetonitrile 0.6%, and mass flow rate 6kg / h.

[0025] like Figure 2 As shown, the separation device of the mixed liquid of acetonitrile, triethylamine and water of the present invention comprises an extraction unit, a first distillation unit, a second distillation unit and a separation unit; the extraction unit is provided with a first feed port for inputting the mixed liquid of acetonitrile, triethylamine and water, a second feed port for inputting an entrainer, and a water phase discharge end and an oil phase discharge end, and the first feed port and the second feed port can be two separate feed ports or a combined feed port; the extraction unit utilizes the extraction of the entrainer to obtain a stratified water phase and an oil phase containing acetonitrile, triethylamine, a small amount of residual water and the entrainer.

[0026] The oil phase discharge end of the extraction unit is connected to the feed end of the first distillation unit. The top extraction end of the first distillation unit is connected to the feed end of the separation unit, and the separation unit layers the top distillate of the first distillation unit. The first discharge end of the separation unit is the water phase discharge end, which outputs most of the water, and the second discharge end of the separation unit is the oil phase discharge end, which outputs most of the entrainer. The first branch of the oil phase discharge end is connected to the reflux port of the first distillation unit, and the second branch of the oil phase discharge end extracts the recovered entrainer. These entrainers can be recovered and reused, that is, the separated entrainer is recovered and provided to the extraction unit for continued use.

[0027] The bottom extraction end of the first distillation unit is connected to the feed end of the second distillation unit. The second distillation unit distills the bottom liquid of the first distillation unit, and acetonitrile is extracted from the top fraction of the second distillation unit, and triethylamine is extracted from the bottom of the second distillation unit.

[0028] use Figure 2 The method for separating the mixed liquid by the separation device shown is as follows (especially for the mixed liquid with a water content of > 5%, but not limited thereto): Adding a mixture of acetonitrile, triethylamine and water and an azeotropic agent into an extraction unit, performing an extraction step, first separating and obtaining an oil phase and a water phase, wherein the separated oil phase is a mixture of acetonitrile, triethylamine, a small amount of water and an azeotropic agent, and the oil phase is sent to a first distillation step as a first feed for separation; In the first distillation step, the oil phase output from the extraction unit enters the first distillation unit for distillation treatment, so that the entrainer and water are azeotropically distilled; the distillate from the first distillation unit enters the separation unit for separation, and water and the entrainer are obtained; In the second distillation step, the bottom liquid of the first distillation step enters the second distillation unit for distillation treatment to obtain separated acetonitrile and triethylamine.

[0029] The azeotropic agent and water form a heterogeneous azeotrope, so that the water and the azeotropic agent in the distillate can be separated by liquid-liquid phase separation; the specific azeotropic agent can be dichloromethane, chloroform or isoprene.

[0030] Taking advantage of the immiscible characteristics of the azeotropic agent and water, combined with extraction technology, the acetonitrile and triethylamine in the mixed solution are first subjected to liquid-liquid extraction to remove most of the water, thereby reducing the pressure of subsequent azeotropic dehydration.

[0031] The mass ratio of the mixed liquid to the entrainer in the extraction step can be 1:1.5-1:3; the first distillation step uses a distillation tower with 30-45 theoretical plates, and feeds at the 15th-20th plate; the second distillation step uses a distillation tower with 40-60 theoretical plates, and feeds at the 20th-30th plate; the reflux ratio of the distillation tower is controlled to be 1-5.

[0032] Use the above Figure 2 Specific embodiments of the separation device and separation method (Example 2) In this embodiment, the mixture of acetonitrile, triethylamine and water comprises the following composition and mass fractions: 1% to 20% water, 70% to 85% acetonitrile, and 2% to 5% triethylamine. The mixture is treated by extraction + azeotropic distillation. The heterogeneous azeotropic agent is dichloromethane. The mixture and dichloromethane are pumped into the extraction tower (i.e., the extraction unit) in a mass ratio of 1:1.5 to 1:3. In this embodiment, the mass ratio of 1:1.5 is used for treatment, wherein the treatment capacity of the mixture is 333 kg / h and that of dichloromethane is 500 kg / h.

[0033] The main components and mass fractions of the water phase extracted from the top of the extraction tower are: 98.97% water, 1.03% dichloromethane, and the processing capacity is 14kg / h. The main components and mass fractions of the oil phase extracted from the bottom of the extraction tower are: 4.4% water, 33.8% acetonitrile, 61.0% dichloromethane, 0.8% triethylamine, and the processing capacity is 819kg / h.

[0034] After extraction and stratification in the extraction tower, the lower oil phase is pumped into the azeotropic distillation tower (i.e., the first distillation unit) at a flow rate of 819 kg / h. The azeotropic distillation tower has 30 theoretical plates. The 15th plate is fed and fully refluxed until the top temperature is stabilized at 38°C and the bottom temperature is stabilized at 69°C. The top of the azeotropic distillation tower is extracted to the stratification tank (i.e., the separation unit) for stratification, and part of the oil phase is controlled to reflux to the azeotropic distillation tower. The stratified water phase is fully extracted; the composition and mass fraction of the water phase extracted from the top of the stratification tank are: 98.7% water, 1.3% dichloromethane, and the mass flow rate is 36 kg / h. The composition and mass fraction of the oil phase refluxed from the stratification tank are: 0.2% water, 99.8% dichloromethane, and the mass flow rate is 3323 kg / h. The composition and mass fraction of the oil phase extracted from the stratification tank are: 0.2% water, 99.8% dichloromethane, and the mass flow rate is 500 kg / h, which is returned to the extraction tower. The bottom of the azeotropic distillation tower obtains a mixed liquid of acetonitrile and triethylamine with extremely low water content (water content ≤100ppm bottom liquid), whose composition and mass fraction are: acetonitrile 97.6%, triethylamine 2.4%, and mass flow rate 283kg / h. The bottom liquid output from the azeotropic distillation tower is sent to the atmospheric distillation tower (i.e., the second distillation unit), acetonitrile is extracted from the top of the atmospheric distillation tower, and its composition and mass fraction are: acetonitrile 99.8%, triethylamine 0.2%, and mass flow rate 277kg / h. The bottom of the atmospheric distillation tower extracts triethylamine, whose composition and mass fraction are: triethylamine 99.5%, acetonitrile 0.5%, and mass flow rate 6kg / h.

[0035] Use the above Figure 2 Specific embodiment of the separation device and separation method (Example 3) In this embodiment, the mixture of acetonitrile, triethylamine and water contains the following composition and mass fractions: 1% to 20% water, 70 to 85% acetonitrile, and 2 to 5% triethylamine. The mixture is treated by extraction + azeotropic distillation, and isoprene is used as a heterogeneous azeotropic agent for the experiment. The mixture and isoprene are pumped into an extraction tower (i.e., extraction unit) at a mass ratio of 1:1.5 to 1:3. In this embodiment, a mass ratio of 1:1.5 is used for treatment, wherein the treatment capacity of the mixture is 333 kg / h and that of isoprene is 500 kg / h.

[0036] The main components and mass fractions of the water phase extracted from the top of the extraction tower are: 99.07% water, 0.93% isoprene, and the processing capacity is 8kg / h. The main components and mass fractions of the oil phase extracted from the bottom of the extraction tower are: 5.1% water, 33.6% acetonitrile, 60.6% isoprene, 0.7% triethylamine, and the processing capacity is 825kg / h.

[0037] After the extraction tower is separated, the lower oil phase is pumped into the azeotropic distillation tower (i.e., the first distillation unit) at a flow rate of 825 kg / h. The distillation tower has 40 theoretical plates. The material is fed on the 20th plate and fully refluxed until the top temperature is stabilized at 34°C and the bottom temperature is stabilized at 58°C. The top of the azeotropic distillation tower is extracted to the separation tank (i.e., the separation unit) for separation, and part of the oil phase is controlled to reflux to the azeotropic distillation tower. The water phase separated by the separation tank is fully extracted. The composition and mass fraction of the water phase extracted from the top of the separation tank are: 99.07% water, 0.93% isoprene, and the mass flow rate is 42 kg / h. The composition and mass fraction of the oil phase refluxed from the top of the separation tank are: 0.2% water, 99.8% isoprene, and the mass flow rate is 2854 kg / h. The composition and mass fraction of the oil phase extracted from the separation tank are: 0.1% water, 99.9% isoprene, and the mass flow rate is 500 kg / h, which is returned to the extraction tower. The bottom of the azeotropic distillation tower obtains a mixed liquid of acetonitrile and triethylamine with extremely low water content (water content ≤100ppm bottom liquid), whose composition and mass fraction are: acetonitrile 97.5%, triethylamine 2.5%, and mass flow rate 283kg / h. The bottom liquid output from the azeotropic distillation tower is sent to the atmospheric distillation tower (the second distillation unit), and acetonitrile is produced from the top of the atmospheric distillation tower, and its composition and mass fraction are: acetonitrile 99.7%, triethylamine 0.3%, and mass flow rate 277kg / h. The bottom of the atmospheric distillation tower produces triethylamine, and its composition and mass fraction are: triethylamine 99.6%, acetonitrile 0.4%, and mass flow rate 6kg / h.

[0038] Example 1 ( Figure 1 ) For a mixed liquid with a water content of 5%, a direct azeotropic distillation scheme is used to compare examples 2 and 3 ( Figure 2), the water phase obtained from the azeotropic distillation tower is significantly increased, and the reflux oil phase is increased, which will lead to a long processing time and increased energy consumption of the equipment. When the water content in the raw material is higher, the energy consumption of the treatment method in Example 1 will be higher. Therefore, the extraction + azeotropic distillation method (Examples 2 and 3) is used for treatment to save energy and improve work efficiency.

[0039] Therefore, the present invention Figure 2 The embodiment of the invention uses an azeotropic agent to first extract the mixed solution of acetonitrile, triethylamine and water, separates most of the water, and then performs azeotropic distillation to make the water in the mixed solution basically completely separated from the system, and finally separates acetonitrile and triethylamine by conventional distillation. The method is simpler in process and can be dehydrated without complex equipment. The azeotropic agent can be recycled after distillation and separation, and no waste liquid is generated, which solves the current series of problems such as high waste liquid treatment cost of acetonitrile, triethylamine and water, high equipment cost, and difficult recycling.

[0040] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for separating a mixed solution of acetonitrile, triethylamine and water, characterized in that: The following steps are involved: In a first distillation step, a mixed liquid and an azeotropic agent are used as feeds for distillation treatment, wherein the mixed liquid includes acetonitrile, triethylamine and water, and the azeotropic agent can azeotropize with water; Separation step: separating the distillate from the first distillation step to obtain water and an azeotropic agent; In the second distillation step, the bottom liquid of the first distillation step is distilled to obtain separated acetonitrile and triethylamine.

2. The separation method according to claim 1, characterized in that: The entrainer is immiscible with water; and the separation step is to separate water and the entrainer by extraction.

3. The separation method according to claim 2, characterized in that: The method further comprises an extraction step before the first distillation step, wherein the mixed liquid and the azeotropic agent are subjected to extraction treatment, and the extracted oil phase is used as feed for the first distillation step.

4. The separation method according to claim 3, characterized in that: The water content in the mixed solution is ≥5%wt.

5. The separation method according to claim 1 or 2, characterized in that: The azeotropic agent is dichloromethane, chloroform or isoprene.

6. The separation method according to claim 1, characterized in that: The method also includes recovering the azeotropic agent obtained in the separation step and providing it to the first distillation step for further distillation treatment.

7. The separation method according to claim 3, characterized in that: The method also includes recovering the azeotropic agent obtained in the separation step and providing the azeotropic agent to the extraction step for extraction treatment.

8. The separation method according to claim 3, characterized in that: The mass ratio of the mixed liquid to the entrainer in the extraction step is 1:1.5-1:

3.

9. A separation device for a mixed solution of acetonitrile, triethylamine and water, characterized in that: It includes a first distillation unit, a separation unit and a second distillation unit; The feed of the first distillation unit includes a mixed liquid and an azeotropic agent, the mixed liquid includes acetonitrile, triethylamine and water, and the azeotropic agent can azeotropize with water; the distillate of the first distillation unit includes an azeotrope of the azeotropic agent and water, and the bottom liquid includes acetonitrile and triethylamine; The separation unit and the second distillation unit receive the distillate and the bottom liquid of the first distillation unit respectively and separate them.

10. The separation device according to claim 9, characterized in that: The entrainer is immiscible with water, and an extraction unit is provided before the first distillation unit to extract the mixed liquid and the entrainer; the oil phase outlet of the extraction unit is connected to the feed port of the first distillation unit.

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