Method for separating and refining fusel oil in Fischer-Tropsch synthesis

Abstract

The invention discloses a method for separating and refining fusel oil in Fischer-Tropsch synthesis, which comprises the following steps: carrying out pressurized rectification treatment on fusel oil to remove acids, C4 + alcohol and part of n-butyl alcohol, carrying out dehydration treatment on tower top steam after removal through membrane separation, carrying out normal-pressure rectification treatment on a dehydrated intermediate product to remove light components, and carrying out vacuum distillation treatment on the dehydrated intermediate product to obtain the fusel oil. Carrying out reduced pressure rectification treatment on the tower bottoms after the light components are removed to remove propyl alcohol and butanol, carrying out tower top steam condensation on one part of the tower bottoms, returning the other part of the tower bottoms to the tower, extracting an ethanol finished product, carrying out normal pressure rectification treatment on the tower bottoms to remove isopropyl alcohol, carrying out normal pressure rectification treatment on the tower bottoms after removal for separation, and obtaining an n-propyl alcohol finished product at the tower top; and obtaining an n-butyl alcohol finished product from the tower kettle. Through cooperative coupling of multistage rectification and membrane separation, stage-by-stage efficient separation and resource utilization of components with different polarities and boiling points in fusel oil are realized, and three types of products of ethanol, normal propyl alcohol and normal butanol are synchronously produced.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical engineering, and particularly relates to a method for separating and refining fusel oil in Fischer-Tropsch synthesis. Background Art

[0002] Fischer-Tropsch synthesis is a process that uses syngas (a mixture of carbon monoxide and hydrogen) as a raw material to synthesize liquid hydrocarbons or hydrocarbons under the action of a catalyst and appropriate conditions. This process can convert syngas generated from coal, natural gas, or biomass into liquid fuels such as lubricating oils and synthetic fuels, and most of the generated alkanes tend to be straight-chain, making them suitable as diesel fuels. However, fusel oil is produced during the Fischer-Tropsch synthesis process. Fusel oil is a mixture of various alcohols generated during fermentation or synthesis, commonly including amyl alcohol, butanol, isopentyl alcohol, isobutanol, etc., and their production ratios vary under different synthesis conditions and raw materials. The presence of fusel oil can affect the quality of products. Especially in the production of fuels and chemicals, its high concentration may cause bad odors and reduce product performance.

[0003] Existing separation technologies mostly rely on multi-stage atmospheric and vacuum distillation combined with acid-base neutralization treatment, and there are problems such as long process flow, serious equipment corrosion, and insufficient ethanol purity caused by entrainment of high-boiling acids and light components. For example, traditional extraction methods use solvents such as propylene carbonate, acetonitrile, or methanol-alkali solution. Although they can partially deoxygenate, they face challenges such as high toxicity of the extractant, boiling point limitations (unable to handle high-boiling fractions), high hydrocarbon loss rate, and complex processes (requiring multiple-step reactions or distillations). In addition, conventional distillation has high energy consumption and has not effectively solved the separation problem of the azeotropic system of low-boiling aldehyde / ketone compounds and alcohols, resulting in low energy utilization efficiency and insufficient removal efficiency of light components. Although existing membrane separation technologies can dehydrate, they have not been coupled and optimized with the distillation system, and the separation effect is limited. The cascade utilization of heat energy in the multi-column series process is insufficient, further restricting the economy and product recovery rate. Therefore, developing a method for separating and refining fusel oil in Fischer-Tropsch synthesis that is efficient, low-cost, and easy to operate is of great significance for improving the quality and market competitiveness of Fischer-Tropsch synthesis products. Summary of the Invention

[0004] To solve the deficiencies of the existing technology, the purpose of the present invention is to provide a method for separating and refining fusel oil in Fischer-Tropsch synthesis. Through the synergistic coupling of multi-stage distillation and membrane separation, the step-by-step efficient separation and resource utilization of components with different polarities and boiling points in fusel oil are realized. The whole process adopts a segmented and precise process to simultaneously produce three high-value-added products: ethanol, n-propanol, and n-butanol.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions: A method for separating and refining fusel oil in Fischer-Tropsch synthesis, comprising the following steps: S1. Remove acids, C4+ alcohols and part of n-butanol from fusel oil through pressurized rectification. S2. Dehydrate the overhead steam after removal through membrane separation. S3. Remove light components from the intermediate product after dehydration through atmospheric rectification. S4. Remove propanol and butanol from the bottom liquid after removing light components through vacuum rectification. After the overhead steam is condensed, part of it is refluxed into the tower and the other part is taken out as the finished ethanol product. S5. Remove isopropanol from the bottom liquid through atmospheric rectification. S6. Separate the bottom liquid after removal through atmospheric rectification. The overhead product is the finished n-propanol product and the bottom product is the finished n-butanol product.

[0006] Preferably, in the aforementioned step S1, before the pressurized rectification treatment, first heat-exchange the fusel oil with the bottom liquid of the pressurized rectification.

[0007] Preferably, in the aforementioned step S1, the operating pressure of the pressurized rectification is 0.5 - 0.7 MPa, the overhead temperature is 100 - 115 °C, the bottom temperature is 145 - 158 °C, the number of trays is 50 - 60, and the reflux ratio is 2.5 - 3.5; in step S2, the membrane separation unit uses a polyimide membrane or a ceramic molecular sieve membrane, and the vacuum degree on the downstream side of the membrane module is 3 - 10 kPa.

[0008] Preferably, in the aforementioned step S4, the operating pressure of the vacuum rectification is -0.08 - -0.095 MPa, the overhead temperature is 55 - 60 °C, the number of trays is 60 - 70, and the reflux ratio is 8 - 12.

[0009] A separation and purification device for fusel oil in Fischer-Tropsch synthesis, comprising: A pressurized rectification tower for performing pressurized rectification treatment on fusel oil to remove acids, C4+ alcohols and part of n-butanol; A membrane separation unit connected to the top discharge port of the pressurized rectification tower for dehydrating the overhead steam; An atmospheric rectification tower I connected to the bottom discharge port of the membrane separation unit for removing light components; A vacuum rectification tower connected to the bottom discharge port of the atmospheric rectification tower I for removing propanol and butanol from the bottom liquid; An atmospheric rectification tower II connected to the bottom discharge port of the vacuum rectification tower for removing isopropanol from the bottom liquid; An atmospheric rectification tower III connected to the bottom discharge port of the atmospheric rectification tower II for separating n-propanol and n-butanol in the bottom liquid.

[0010] Preferably, it further includes a preheater connected to the pressurized rectification tower for preheating the fusel oil.

[0011] Preferably, the top of the aforementioned membrane separation unit is connected to a permeate condenser for cooling the permeate vapor of the membrane module; the permeate condenser is connected to a permeate tank for storing the permeate.

[0012] Preferably, the top of the aforementioned vacuum distillation column is connected to a vacuum distillation column condenser for condensing the overhead vapor; the outlet of the vacuum distillation column condenser is respectively connected to the top of the vacuum distillation column and an ethanol storage tank for refluxing a part of the condensed liquid back into the column and withdrawing a part of the ethanol product.

[0013] Preferably, the aforementioned pressurized distillation column, atmospheric distillation column I, vacuum distillation column, atmospheric distillation column II, and atmospheric distillation column III are all connected to a reboiler.

[0014] Preferably, it further includes a mixing tank. The inlet end of the mixing tank is respectively connected to the reboilers of the pressurized distillation column, atmospheric distillation column I, atmospheric distillation column II, and atmospheric distillation column III, and the outlet end is connected to the reboiler of the vacuum distillation column for collecting the steam condensate in the reboilers of the pressurized distillation column 1, atmospheric distillation column I, atmospheric distillation column II, and atmospheric distillation column III and sending it into the reboiler of the vacuum distillation column.

[0015] The beneficial effects of the present invention are as follows: (1) Through the synergistic coupling of multi-stage distillation and membrane separation, the present invention realizes the step-by-step efficient separation and resource utilization of components with different polarities and boiling points in fusel oil. The whole process adopts a segmented precise process to simultaneously produce three high-value-added products, namely ethanol, n-propanol, and n-butanol, while enriching and treating light components such as methanol, aldehydes, ketones, esters and acids respectively, improving the comprehensive utilization rate of raw materials; the whole set of equipment optimizes the operating parameters of each column through a pressure gradient design (pressurization - atmospheric pressure - vacuum - atmospheric pressure), and cooperates with the pretreatment dehydration of membrane separation, reducing the equipment investment cost and the wastewater discharge, and having significant energy-saving and environmental protection benefits; (2) The present invention uses a pressurized distillation column to pre-remove acids and higher-carbon alcohols, which can effectively reduce the separation load of subsequent processes. Combining the pervaporation dehydration technology of the membrane separation unit with the steam partial pressure difference as the driving force to achieve low-temperature and high-efficiency dehydration, greatly reducing the energy consumption of traditional azeotropic distillation; through the innovative design of side-line extraction of ethanol vapor from the atmospheric distillation column, the entrainment loss of ethanol in the overhead light components and the bottom heavy components is significantly reduced, improving the ethanol recovery rate; by separating propanol and butanol under negative pressure in the vacuum distillation column, not only the decomposition of heat-sensitive substances is avoided by reducing the operating temperature, but also the steam condensate of the reboilers of the other columns is used as a heat source to form a multi-column heat cascade utilization system, reducing the overall steam consumption of the system. Description of the Drawings

[0016] Figure 1 is the process flow chart of the present invention.

[0017] Meanings of the reference numerals in the figures: 1. Pressure rectification column, 2. Membrane separation unit, 3. Atmospheric rectification column I, 4. Vacuum rectification column, 5. Atmospheric rectification column II, 6. Atmospheric rectification column III, 7. Preheater, 8. Permeate condenser, 9. Permeate tank, 10. Vacuum rectification column condenser, 11. Ethanol storage tank, 12. Reboiler. Detailed implementation manners

[0018] The present invention will be specifically introduced below in conjunction with the accompanying drawings and specific embodiments.

[0019] See Figure 1 , a separation and purification device for heavy oil in Fischer-Tropsch synthesis of the present invention, comprising: a pressure rectification column 1 for performing pressure rectification treatment on heavy oil to remove acids, C4+ alcohols and part of n-butanol; a preheater 7 connected to the pressure rectification column 1 for preheating heavy oil; a membrane separation unit 2 connected to the top discharge port of the pressure rectification column 1 for dehydrating the top steam, and the top of the membrane separation unit 2 is connected to a permeate condenser 8 for cooling the permeate steam of the membrane module; the permeate condenser 8 is connected to a permeate tank 9 for storing the permeate; an atmospheric rectification column I 3 connected to the bottom discharge port of the membrane separation unit 2 for removing light components; a vacuum rectification column 4 connected to the bottom discharge port of the atmospheric rectification column I 3 for removing propanol and butanol in the bottom liquid; an atmospheric rectification column II 5 connected to the bottom discharge port of the vacuum rectification column 4 for removing isopropanol in the bottom liquid; an atmospheric rectification column III 6 connected to the bottom discharge port of the atmospheric rectification column II 5 for separating n-propanol and n-butanol in the bottom liquid.

[0020] The top of the vacuum rectification column 4 is connected to a vacuum rectification column condenser 10 for condensing the top steam; the discharge port of the vacuum rectification column condenser 10 is respectively connected to the top of the vacuum rectification column 4 and an ethanol storage tank 11 for returning a part of the condensed liquid to the column and taking out a part of the ethanol product.

[0021] The pressure rectification column 1, the atmospheric rectification column I 3, the vacuum rectification column 4, the atmospheric rectification column II 5 and the atmospheric rectification column III 6 are all connected to a reboiler 12. The device further includes a mixing tank, and the inlet end of the mixing tank is respectively connected to the reboilers 12 of the pressure rectification column 1, the atmospheric rectification column I 3, the atmospheric rectification column II 5 and the atmospheric rectification column III 6, and the outlet end is connected to the reboiler 12 of the vacuum rectification column 4 for collecting the steam condensate in the reboilers 12 of the pressure rectification column 11, the atmospheric rectification column I 3, the atmospheric rectification column II 5 and the atmospheric rectification column III 6 and sending it into the reboiler 12 of the vacuum rectification column 4.

[0022] A separation and purification method for heavy oil in Fischer-Tropsch synthesis, comprising the following steps: S1. The fusel oil from the Fischer-Tropsch synthesis production process (the main components are water, ethanol, methanol, n-propanol, n-butanol, C4+ alcohols (such as n-pentanol, n-hexanol, n-heptanol, etc.), and a small amount of isopropanol, acetate esters (such as methyl acetate and ethyl acetate), ketones (such as acetone, butanone, etc.), aldehydes (such as acetaldehyde, propionaldehyde, butyraldehyde, etc.), and acids (such as acetic acid, propionic acid, n-butyric acid, n-valeric acid, etc.)); The fusel oil is pumped through a feed pump into a preheater 7, exchanges heat with the bottom liquid of the pressurized distillation column 1, and then enters the pressurized distillation column 1 from the middle of the column. Acids, C4+ alcohols, and part of the n-butanol are removed through pressurized distillation. Part of the overhead steam is condensed and used as the overhead reflux liquid to flow back into the column, and part of it enters the membrane separation unit 2 in parallel in the gas phase; S2. The membrane separation unit 2 is composed of multiple membrane modules connected in series. The water and a small amount of solvent in the raw material permeate from the upstream side of the membrane to the downstream side of the membrane through the membrane module. The dehydrated intermediate product enters the atmospheric distillation column I 3 in the gas phase after passing through the last-stage membrane module on the upstream side of the membrane. The downstream side of the membrane uses vacuum pumping and condensation to form a vapor partial pressure difference between the upstream and downstream sides of the membrane, and the inside of the membrane uses vacuum pumping and condensation to generate a driving force. The permeate steam enters the permeate condenser 8 under the suction of the vacuum unit, and the permeate flows to the permeate tank and is then pumped out for treatment; S3. Light components (such as methanol, aldehydes, ketones, esters, etc.) are removed through atmospheric distillation. Part of the overhead steam is condensed and used as the overhead reflux liquid to flow back into the column, and part of it is withdrawn. A part of the fusel oil steam containing ethanol is withdrawn from the side line of the distillation column, condensed by a condenser, temporarily stored in a buffer tank, and then pumped out of the battery limit by a pump. The bottom liquid is pumped into the vacuum distillation column 4 by a pump for further refining; S4. Propanol and butanol are removed through vacuum distillation. Part of the overhead steam is condensed and used as the overhead reflux liquid to flow back into the column to improve the ethanol recovery rate, and part of it is withdrawn as the finished ethanol. The bottom liquid is pumped into the atmospheric distillation column II 5 by a pump; S5. Isopropanol is removed through atmospheric distillation. Part of the overhead steam is condensed and used as the overhead reflux liquid to flow back into the column, and part of it is withdrawn. The bottom liquid is pumped into the atmospheric distillation column III 6 by a pump; S6. n-Propanol and n-butanol are separated through atmospheric distillation. The n-propanol finished product is obtained at the top of the column, and the n-butanol finished product is obtained at the bottom of the column.

[0023] Example 1. Using 5000 kg / h of fusel oil as the raw material (containing 30.9% water, 30.12% ethanol, 14.09% methanol, 11.52% n-propanol, 7.33% n-butanol, 4.22% C4+ alcohols, and 2.02% other impurities), the specific steps are as follows: The fusel oil is preheated and then sent to the pressurized distillation column 1 (operating pressure 0.5 MPa, top temperature 102 °C, bottom temperature 145 °C, 50 trays, reflux ratio 2.5) to remove acids and C4+ alcohols. 40% of the top gas phase is refluxed and 60% enters the membrane separation unit 2. The bottom liquid (acids ≤ 0.1%, C4+ alcohols ≤ 0.3%) enters the subsequent process; the membrane separation unit 2 uses a polyimide pervaporation membrane, operating at a temperature of 85 °C and a vacuum of 8 kPa, dehydrates the intermediate product to a water content of 0.5% and increases the ethanol content to 45.2%. The permeate is discharged after condensation; the dehydrated intermediate product enters the atmospheric distillation column I 3 (top temperature 65 °C, bottom temperature 105 °C, 40 trays, reflux ratio 3). Light components (methanol, aldehydes, ketones, esters, purity ≥ 99%) are taken from the top, and fusel oil vapor with an ethanol content of 95.2% is taken from the side line. The bottom liquid (containing 25.3% n-propanol and 18.7% n-butanol) enters the vacuum distillation column 4 (operating pressure -0.08 MPa, top temperature 60 °C, bottom temperature 90 °C, 60 trays, reflux ratio 8), and ethanol with a purity of 99.5% is taken from the top; the bottom liquid is separated into n-propanol and n-butanol by using the atmospheric distillation column II 5 and the atmospheric distillation column III 6 in combination (99.6% n-propanol is taken from the top and 99.4% n-butanol is taken from the bottom). Finally, the total yields reach 94.2% for ethanol, 96.5% for n-propanol, and 95.8% for n-butanol, and the concentration of COD in the wastewater is reduced to 180 mg / L.

[0024] Example 2: Using 8000 kg / h of fusel oil (with the same composition as in Example 1) as the raw material, the specific steps are as follows: The fusel oil is preheated and then fed into the pressurized distillation column 1 (operating pressure 0.6 MPa, top temperature 110 °C, bottom temperature 152 °C, 55 trays, reflux ratio 3). After removing acids and C4+ alcohols, 50% of the top gas phase is refluxed and 50% enters the membrane separation unit 2. The bottom liquid (acids ≤ 0.1%, C4+ alcohols ≤ 0.3%) enters the subsequent process; the membrane separation unit 2 uses a ceramic molecular sieve membrane, with an operating temperature of 90 °C and a vacuum degree of 5 kPa, dehydrates the intermediate product to a water content of 0.3% and increases the ethanol content to 47.5%, and the permeate is discharged; the dehydrated intermediate product enters the atmospheric distillation column I 3 (top temperature 65 °C, bottom temperature 105 °C, 45 trays, reflux ratio 3.5), the light components (methanol, aldehydes, ketones, esters, purity ≥ 99%) are taken out from the top, the fusel oil vapor with an ethanol content of 96.8% is taken out from the side line, and the bottom liquid (containing 28.1% n-propanol and 20.4% n-butanol) enters the vacuum distillation column 4 (operating pressure -0.09 MPa, top temperature 58 °C, bottom temperature 80 °C, 65 trays, reflux ratio 10) to obtain ethanol with a purity of 99.7%. After the bottom liquid is separated by the atmospheric distillation column II 5 and the atmospheric distillation column III 6 (99.8% n-propanol is taken out from the top and 99.5% n-butanol is taken out from the bottom), the n-propanol recovery rate is increased to 97.1% and the n-butanol recovery rate is increased to 96.3%, and the ethanol recovery rate reaches 95.6%, and the COD concentration in the wastewater is reduced to 198 mg / L.

[0025] Comparative example: Using fusel oil with a treatment volume of 5000 kg / h as the raw material (the composition is the same as that in Example 1), the traditional multi-column azeotropic distillation process is used for separation, and the specific steps are as follows: First, dehydration is carried out through an atmospheric dehydration column under atmospheric pressure operation, with a top temperature of 100 °C (the azeotrope contains ethanol / water / methanol, purity 85%), a bottom temperature of 120 °C, 60 trays, and a reflux ratio of 8. After dehydration, the water content of the intermediate product is 8.5%; the intermediate product is fed into an ethanol distillation column for atmospheric pressure operation, with a top temperature of 78 °C (ethanol-water azeotrope, ethanol purity 92.3%), 50 trays, and a reflux ratio of 10. High-purity ethanol cannot be efficiently taken out from the side line. The ethanol recovery rate at the top is 82.5% and the purity is 95%. A large amount of methanol and aldehyde and ketone impurities remain in the bottom; the bottom liquid is fed into an atmospheric distillation column, with a top temperature of 97 °C (n-propanol purity 88.4%) and a bottom temperature of 118 °C (n-butanol purity 85.7%), 50 trays, and a reflux ratio of 6. The total recovery rates of n-propanol and n-butanol are 78.6% and 72.3% respectively, and the COD in the wastewater is as high as 1200 mg / L.

[0026] Comparing Example 1 with the comparative example, it can be seen that the water content of the intermediate product after dehydration in the comparative example is still as high as 8.5%, which is significantly inferior to the membrane separation dehydration effect of Example 1. This leads to the subsequent ethanol rectification column being difficult to efficiently separate due to the water-ethanol azeotropic effect, reducing the ethanol yield, and leaving a large amount of methanol and aldehyde-ketone impurities in the bottom of the column. Moreover, the total yields of n-propanol and n-butanol are only 78.6% and 72.3% respectively, which are significantly lower than 96.5% and 95.8% of Example 1. The content of COD in the treated wastewater is relatively high, fully demonstrating that Example 1 has achieved a breakthrough improvement in terms of product purity, yield, energy consumption, and environmental protection through the coupling of membrane separation-vacuum rectification and heat integration technology.

[0027] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by using equivalent replacements or equivalent transformations fall within the protection scope of the present invention.

Claims

1. A method for separating and refining fusel oil in Fischer-Tropsch synthesis, characterized in that: The following steps are involved: S1, removing acids, C4+ alcohols and part of n-butanol from fusel oil by pressure distillation; S2, the tower top steam after removal is dehydrated by membrane separation; S3, the dehydrated intermediate product is treated by atmospheric distillation to remove light components; S4, the bottom liquid after the light components are removed is treated by vacuum distillation to remove propanol and butanol, and a portion of the overhead vapor is condensed and refluxed into the tower, and the other portion is extracted as ethanol product; S5, the bottom liquid of the tower is treated by atmospheric distillation to remove isopropanol; S6. The bottom liquid after removal is separated by atmospheric distillation, and the top of the tower obtains the finished product of n-propanol, and the bottom of the tower obtains the finished product of n-butanol.

2. The method for separating and refining fusel oil in Fischer-Tropsch synthesis according to claim 1, characterized in that: In the step S1, before the pressure distillation treatment, the fusel oil is first heat exchanged with the bottom liquid of the pressure distillation tower.

3. The method for separating and refining fusel oil in Fischer-Tropsch synthesis according to claim 1, characterized in that: In the step S1, the operating pressure of the pressure distillation is 0.5~0.7 MPa, the tower top temperature is 100~115°C, the tower bottom temperature is 145~158°C, the number of tower plates is 50~60 layers, and the reflux ratio is 2.5~3.5; in the step S2, the membrane separation unit adopts a polyimide membrane or a ceramic molecular sieve membrane, and the vacuum degree on the downstream side of the membrane assembly is 3~10 kPa.

4. The method for separating and refining fusel oil in Fischer-Tropsch synthesis according to claim 1, characterized in that: In the step S4, the operating pressure of the vacuum distillation is -0.08~-0.095 MPa, the tower top temperature is 55~60°C, the number of tower plates is 60~70 layers, and the reflux ratio is 8~12.

5. A separation and refining device for fusel oil in Fischer-Tropsch synthesis, characterized in that: include: A pressure distillation tower (1) is used to perform pressure distillation treatment on fusel oil to remove acids, C4+ alcohols and part of n-butanol; The membrane separation unit (2) is connected to the top discharge port of the pressurized distillation tower (1) and is used for dehydrating the steam at the top of the tower; Atmospheric distillation tower I (3), connected to the bottom outlet of the membrane separation unit (2), for removing light components; A vacuum distillation tower (4) connected to the bottom outlet of the atmospheric distillation tower I (3) for removing propanol and butanol from the bottom liquid of the tower; Atmospheric distillation tower II (5), connected to the bottom discharge port of vacuum distillation tower (4), for removing isopropanol from the bottom liquid; The atmospheric distillation tower III (6) is connected to the bottom discharge port of the atmospheric distillation tower II (5) and is used to separate the n-propanol and n-butanol in the bottom liquid of the tower.

6. The separation and refining device for fusel oil in Fischer-Tropsch synthesis according to claim 5, characterized in that: It also includes a preheater (7) connected to the pressurized distillation tower (1) for preheating the fusel oil.

7. The separation and refining device for fusel oil in Fischer-Tropsch synthesis according to claim 5, characterized in that: The top of the membrane separation unit (2) is connected to a permeate condenser (8) for cooling the permeate vapor of the membrane assembly; the permeate condenser (8) is connected to a permeate tank (9) for storing the permeate.

8. The separation and refining device for fusel oil in Fischer-Tropsch synthesis according to claim 5, characterized in that: The top of the vacuum distillation tower (4) is connected to a vacuum distillation tower condenser (10) for condensing the tower top steam; the discharge port of the vacuum distillation tower condenser (10) is respectively connected to the top of the vacuum distillation tower (4) and the ethanol storage tank (11) for returning part of the condensed liquid to the tower and taking out part of the ethanol product.

9. The separation and refining device for fusel oil in Fischer-Tropsch synthesis according to claim 5, characterized in that: The pressure distillation tower (1), the atmospheric distillation tower I (3), the vacuum distillation tower (4), the atmospheric distillation tower II (5) and the atmospheric distillation tower III (6) are all connected to a reboiler (12).

10. The device for separating and refining fusel oil in Fischer-Tropsch synthesis according to claim 9, characterized in that: The invention also comprises a mixing tank (13), wherein the inlet end of the mixing tank (13) is respectively connected to the reboilers (12) of the pressure distillation tower (1), the atmospheric distillation tower I (3), the atmospheric distillation tower II (5) and the atmospheric distillation tower III (6), and the outlet end of the mixing tank (13) is connected to the reboiler (12) of the vacuum distillation tower (4), and is used to collect steam condensed water in the reboilers (12) of the pressure distillation tower (1), the atmospheric distillation tower I (3), the atmospheric distillation tower II (5) and the atmospheric distillation tower III (6), and send the condensed water into the reboiler (12) of the vacuum distillation tower (4).

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