Separating and refining device for fusel oil in Fischer-Tropsch synthesis
By employing a synergistic coupling method of multi-stage distillation and membrane separation, the problems of lengthy and energy-intensive fusel oil separation technology in the Fischer-Tropsch synthesis process have been solved, achieving efficient separation and resource utilization, and improving product quality and economy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2026-04-14
AI Technical Summary
Existing separation technologies for fusel oils in Fischer-Tropsch synthesis suffer from problems such as lengthy process flow, severe equipment corrosion, high energy consumption, limited separation effect, and low resource utilization. In particular, the entrainment of high-boiling-point acids and light components leads to insufficient ethanol purity, and traditional extraction methods and membrane separation technologies have failed to effectively solve the separation problem of azeotropic systems.
A synergistic coupling method of multi-stage distillation and membrane separation is adopted. By combining pressurized distillation, membrane separation, atmospheric distillation and vacuum distillation, the efficient separation of different polarity and boiling point components in fusel oil is achieved stepwise. Combined with the pervaporation dehydration technology of the membrane separation unit and the cascade utilization of thermal energy of the reboiler, the operating parameters are optimized to reduce energy consumption and equipment costs.
This technology enables efficient separation and resource utilization of different components in fusel oil, reduces equipment investment and energy consumption, improves the recovery rates of ethanol, n-propanol and n-butanol, reduces wastewater discharge and heat energy consumption, and enhances product quality and market competitiveness.
Smart Images
Figure CN224113314U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of chemical technology, specifically relating to a separation and purification device for fusel oil in Fischer-Tropsch synthesis. Background Technology
[0002] Fischer-Tropsch synthesis is a process that uses syngas (a mixture of carbon monoxide and hydrogen) as a feedstock to synthesize liquid hydrocarbons or hydrocarbons under catalytic conditions and appropriate conditions. This process can convert syngas from coal, natural gas, or biomass into liquid fuels such as lubricating oils and synthetic fuels, and the resulting alkanes mostly tend to be straight-chain, making them suitable for diesel fuel. However, Fischer-Tropsch synthesis produces fusel oils, a mixture of various alcohols generated during fermentation or synthesis, commonly including pentanol, butanol, isoamyl alcohol, and isobutanol, the proportions of which vary depending on the synthesis conditions and feedstock. The presence of fusel oils can affect product quality, especially in fuel and chemical production; high concentrations can lead to unpleasant odors and reduced product performance.
[0003] Existing separation technologies largely rely on multi-stage atmospheric and vacuum distillation combined with acid-base neutralization, which suffers from problems such as lengthy process flows, severe equipment corrosion, and insufficient ethanol purity due to the entrainment of high-boiling-point acids and light components. For example, traditional extraction methods use solvents such as propylene carbonate, acetonitrile, or methanol-based alkaline solutions, which can partially deoxygenate but face challenges such as high extractant toxicity, boiling point limitations (inability to handle high-boiling-point fractions), high hydrocarbon loss rates, and complex processes (requiring multiple reaction steps or distillation). Furthermore, conventional distillation is energy-intensive and has not effectively solved the separation problem of low-boiling-point aldehydes / ketones from azeotropic systems with alcohols, resulting in low energy utilization and insufficient removal efficiency of light components. While existing membrane separation technologies can dehydrate, they are not coupled and optimized with the distillation system, and their separation effect is limited. In multi-tower series processes, insufficient utilization of thermal energy further restricts economic efficiency and product recovery rates. Therefore, developing an efficient, low-cost, and easy-to-operate method for separating and purifying fusel oils in Fischer-Tropsch synthesis is of great significance for improving the quality and market competitiveness of Fischer-Tropsch synthesis products. Summary of the Invention
[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a separation and refining device for fusel oil in Fischer-Tropsch synthesis. Through the synergistic coupling of multi-stage distillation and membrane separation, it achieves efficient separation and resource utilization of components with different polarities and boiling points in fusel oil. The entire process adopts a segmented precision process, simultaneously producing three high-value-added products: ethanol, n-propanol, and n-butanol.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A method for separating and purifying fusel oils in Fischer-Tropsch synthesis includes the following steps:
[0007] S1. Remove acids, C4+ alcohols, and some n-butanol from fusel oil by pressurized distillation;
[0008] S2. The removed top steam from the tower is dehydrated by membrane separation.
[0009] S3. The dehydrated intermediate product is subjected to atmospheric distillation to remove light components;
[0010] S4. After removing the light components, the bottom liquid of the column is treated by vacuum distillation to remove propanol and butanol. After the top vapor of the column is condensed, part of it is refluxed into the column, and the other part is used to collect the ethanol product.
[0011] S5. Isopropanol is removed from the bottom liquid of the column by atmospheric distillation.
[0012] S6. The bottom liquid after removal is separated by atmospheric distillation. The top of the column yields n-propanol, and the bottom of the column yields n-butanol.
[0013] Preferably, in step S1 above, before the pressurized distillation process, the fusel oil is first exchanged with the liquid in the bottom of the pressurized distillation column for heat exchange.
[0014] Preferably, in the aforementioned step S1, the operating pressure of the pressurized distillation is 0.5~0.7 MPa, the top temperature is 100~115 ℃, the bottom temperature is 145~158 ℃, the number of trays is 50~60, and the reflux ratio is 2.5~3.5.
[0015] Preferably, in step S2 above, 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.
[0016] Preferably, in step S4 above, the operating pressure of the vacuum distillation column is -0.08 to -0.095 MPa, the top temperature is 55 to 60 ℃, the number of trays is 60 to 70, and the reflux ratio is 8 to 12.
[0017] A separation and purification apparatus for fusel oils in Fischer-Tropsch synthesis includes:
[0018] A pressurized distillation column is used to perform pressurized distillation on fusel oil to remove acids, C4+ alcohols and some n-butanol;
[0019] The membrane separator unit is connected to the top outlet of the pressurized distillation column and is used to dehydrate the top steam of the column.
[0020] Atmospheric distillation column I is connected to the bottom outlet of the membrane separator unit and is used to remove light components;
[0021] A vacuum distillation column, connected to the bottom outlet of atmospheric distillation column I, is used to remove propanol and butanol from the bottom liquid of the column;
[0022] Atmospheric distillation column II is connected to the bottom outlet of the vacuum distillation column and is used to remove isopropanol from the bottom liquid of the column.
[0023] Atmospheric distillation column III is connected to the bottom outlet of atmospheric distillation column II and is used to separate n-propanol and n-butanol from the bottom liquid of the column.
[0024] Preferably, it also includes a preheater connected to a pressurized distillation column for preheating fusel oil.
[0025] Preferably, the top of the aforementioned membrane separation unit is connected to a permeate condenser for cooling the permeate vapor in the membrane module; the permeate condenser is connected to a permeate tank for storing the permeate.
[0026] Preferably, the top of the aforementioned vacuum distillation column is connected to a vacuum distillation column condenser for condensing the top vapor of the column; the outlet of the vacuum distillation column condenser is connected to the top of the vacuum distillation column and the ethanol storage tank respectively, for returning part of the condensed liquid back into the column and collecting part of the ethanol product.
[0027] 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.
[0028] Preferably, the system further includes a mixing tank, the inlet of which is connected to the reboilers of the pressurized distillation column, atmospheric distillation column I, atmospheric distillation column II, and atmospheric distillation column III, respectively, and the outlet of which is connected to the reboiler of the vacuum distillation column. The mixing tank is used to collect the steam condensate from the reboilers of the pressurized distillation column I, atmospheric distillation column I, atmospheric distillation column II, and atmospheric distillation column III, and send it to the reboiler of the vacuum distillation column.
[0029] The advantages of this utility model are:
[0030] (1) This utility model achieves efficient separation and resource utilization of different polarity and boiling point components in fusel oil through the synergistic coupling of multi-stage distillation and membrane separation. The whole process adopts segmented precision process, and simultaneously produces three high value-added products: ethanol, n-propanol and n-butanol. At the same time, methanol, aldehydes, ketones and esters and acid substances are enriched and treated separately, which improves the comprehensive utilization rate of raw materials. The whole set of equipment optimizes the operating parameters of each tower through pressure gradient design (pressurization-atmospheric pressure-depressurization-atmospheric pressure), and with the pretreatment dehydration of membrane separation, the equipment investment cost is reduced and the wastewater discharge is reduced, which has significant energy-saving and environmental protection benefits.
[0031] (2) The present invention adopts a pressurized distillation column to remove acids and high carbon alcohols in advance, which can effectively reduce the separation load of subsequent processes. Combined with the pervaporation dehydration technology of the membrane separation unit, the steam partial pressure difference is used as the driving force to achieve low-temperature and high-efficiency dehydration, which greatly reduces the energy consumption of traditional azeotropic distillation. The innovative design of taking out ethanol vapor from the side line of the atmospheric distillation column significantly reduces the entrainment loss of ethanol in the light components at the top of the column and the heavy components at the bottom of the column, and improves the ethanol recovery rate. By separating propanol and butanol under negative pressure conditions through the vacuum distillation column, not only is the decomposition of heat-sensitive substances avoided by reducing the operating temperature, but the steam condensate of the reboiler of the other columns is also used as a heat source to form a multi-column thermal energy cascade utilization system, which reduces the overall steam consumption of the system. Attached Figure Description
[0032] Figure 1 This is a process flow diagram of this utility model.
[0033] The meanings of the labels in the attached diagram are as follows: 1. Pressurized distillation column, 2. Membrane separator, 3. Atmospheric distillation column I, 4. Vacuum distillation column, 5. Atmospheric distillation column II, 6. Atmospheric distillation column III, 7. Preheater, 8. Permeate condenser, 9. Permeate tank, 10. Vacuum distillation column condenser, 11. Ethanol storage tank, 12. Reboiler. Detailed Implementation
[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0035] See Figure 1 This utility model discloses a separation and refining apparatus for fusel oil in Fischer-Tropsch synthesis, comprising: a pressurized distillation column 1 for pressurized distillation of fusel oil to remove acids, C4+ alcohols, and part of n-butanol; a preheater 7 connected to the pressurized distillation column 1 for preheating the fusel oil; a membrane separator 2 connected to the top outlet of the pressurized distillation column 1 for dehydrating the top vapor, wherein the top of the membrane separator 2 is connected to a permeate condenser 8 for cooling the permeate vapor of the membrane module; and a permeate cooling... Condenser 8 is connected to permeate tank 9 for storing permeate; atmospheric distillation column I 3 is connected to the bottom outlet of membrane separator 2 for removing light components; vacuum distillation column 4 is connected to the bottom outlet of atmospheric distillation column I 3 for removing propanol and butanol from the bottom liquid; atmospheric distillation column II 5 is connected to the bottom outlet of vacuum distillation column 4 for removing isopropanol from the bottom liquid; atmospheric distillation column III 6 is connected to the bottom outlet of atmospheric distillation column II 5 for separating n-propanol and n-butanol from the bottom liquid.
[0036] The top of the vacuum distillation column 4 is connected to the vacuum distillation column condenser 10 for condensing the top vapor of the column; the outlet of the vacuum distillation column condenser 10 is connected to the top of the vacuum distillation column 4 and the ethanol storage tank 11 respectively, for returning part of the condensed liquid back into the column and collecting part of the ethanol product.
[0037] The pressurized distillation column 1, atmospheric distillation column I3, vacuum distillation column 4, atmospheric distillation column II5, and atmospheric distillation column III6 are all connected to reboilers 12. The apparatus also includes a mixing tank, the inlet of which is connected to the reboilers 12 of the pressurized distillation column 1, atmospheric distillation column I3, atmospheric distillation column II5, and atmospheric distillation column III6, and the outlet of which is connected to the reboiler 12 of the vacuum distillation column 4. The mixing tank is used to collect the steam condensate from the reboilers 12 of the pressurized distillation column 11, atmospheric distillation column I3, atmospheric distillation column II5, and atmospheric distillation column III6, and send it to the reboiler 12 of the vacuum distillation column 4.
[0038] A method for separating and purifying fusel oils in Fischer-Tropsch synthesis includes the following steps:
[0039] S1. Fusel oil from the Fischer-Tropsch synthesis process (mainly composed of water, ethanol, methanol, n-propanol, n-butanol, C4+ alcohols (referring to n-pentanol, n-hexanol, n-heptanol, etc.) and small amounts of isopropanol, acetates (referring to methyl acetate and ethyl acetate), ketones (referring to acetone, butanone, etc.), aldehydes (referring to acetaldehyde, propionaldehyde, butyraldehyde, etc.) and acids (referring to acetic acid, propionic acid, n-butyric acid, n-valeric acid, etc.)).
[0040] Fusel oil is pumped into preheater 7 via a feed pump. After exchanging heat with the bottom liquid of pressurized distillation column 1, it enters pressurized distillation column 1 from the column. Acids, C4+ alcohols, and part of n-butanol are removed by pressurized distillation. Part of the overhead vapor is condensed and returned to the column as overhead reflux liquid, while part enters the membrane separator unit 2 in parallel in gas phase form.
[0041] S2, Membrane Separator 2 consists of multiple membrane modules connected in series. Moisture and a small amount of solvent in the feed permeate from the upstream side of the membrane to the downstream side of the membrane module. The dehydrated intermediate product enters the atmospheric distillation column I3 in gas phase after passing through the last membrane module on the upstream side. The downstream side of the membrane is vacuumed and condensed to form a vapor pressure difference between the components on the upstream and downstream sides of the membrane. The inner side of the membrane is vacuumed and condensed to generate driving force. The permeate vapor enters the permeate condenser 8 under the suction of the vacuum unit. The permeate flows to the permeate tank and is then pumped out for treatment.
[0042] S3. Light components (methanol, aldehydes, ketones, esters, etc.) are removed by atmospheric distillation. A portion of the condensed vapor from the top of the column is returned to the column as reflux, while the remainder is collected. A portion of fusel oil vapor containing ethanol is collected from the side stream of the distillation column, condensed in a condenser, and temporarily stored in a buffer tank before being pumped out of the boundary area. The bottom liquid is pumped into vacuum distillation column 4 for further purification.
[0043] S4. Propanol and butanol are removed by vacuum distillation. After the vapor at the top of the column is condensed, part of it is returned to the column as reflux liquid to improve the ethanol recovery rate. Part of it is used to collect the finished ethanol. The bottom liquid is pumped into atmospheric distillation column II5.
[0044] S5. Isopropanol is removed by atmospheric distillation. After the top vapor is condensed, part of it is returned to the column as top reflux liquid, and part of it is collected. The bottom liquid is pumped into atmospheric distillation column III6.
[0045] S6. Propanol and butanol are separated by atmospheric distillation. Propanol is obtained at the top of the column, and butanol is obtained at the bottom.
[0046] Example 1: Using fusel oil with a processing capacity of 5000 kg / h as 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:
[0047] The fusel oil, after preheating, is fed into pressurized distillation column 1 (operating pressure 0.5 MPa, top temperature 102 ℃, bottom temperature 145 ℃, 50 trays, reflux ratio 2.5) to remove acids and C4+ alcohols. 40% of the vapor from the top is refluxed, and 60% enters membrane separator unit 2. The bottom liquid (acids ≤0.1%, C4+ alcohols ≤0.3%) enters the subsequent process. Membrane separator unit 2 uses a polyimide pervaporation membrane, operating at 85 ℃ and a vacuum of 8 kPa, to dehydrate the intermediate product to a water content of 0.5% and increase the ethanol content to 45.2%. The permeate is condensed and discharged. The dehydrated intermediate product then enters atmospheric distillation column I3 (top temperature 65 ℃, bottom temperature 105 ℃). At ℃, 40 trays, reflux ratio 3), light components (methanol, aldehydes, ketones, and esters, purity ≥99%) are collected from the top of the column, and fusel oil vapor with 95.2% ethanol content is collected from the side stream. The bottom liquid (containing 25.3% n-propanol and 18.7% n-butanol) enters vacuum distillation column 4 (operating pressure -0.08 MPa, top temperature 60 ℃, bottom temperature 90 ℃, 60 trays, reflux ratio 8), and ethanol with 99.5% purity is collected from the top of the column. The bottom liquid is used in conjunction with atmospheric distillation column II 5 and atmospheric distillation column III 6 (99.6% n-propanol is collected from the top of the column, and 99.4% n-butanol is collected from the bottom of the column) to separate n-propanol and n-butanol. The final total yield is 94.2% ethanol, 96.5% n-propanol, and 95.8% n-butanol, and the COD concentration in the wastewater is reduced to 180 mg / L.
[0048] Example 2: Using fusel oil with a processing capacity of 8000 kg / h (same composition as in Example 1) as raw material, the specific steps are as follows:
[0049] The fusel oil, after preheating, is fed into pressurized distillation column 1 (operating pressure 0.6 MPa, top temperature 110 ℃, bottom temperature 152 ℃, 55 trays, reflux ratio 3) to remove acids and C4+ alcohols. 50% of the vapor phase from the top is refluxed, and 50% enters membrane separator unit 2. The bottom liquid (acids ≤0.1%, C4+ alcohols ≤0.3%) enters the subsequent process. Membrane separator unit 2 uses ceramic molecular sieve membranes, operating at 90 ℃ and a vacuum of 5 kPa, to dehydrate the intermediate product to a water content of 0.3% and an ethanol content of 47.5%, with the permeate discharged. The dehydrated intermediate product then enters atmospheric distillation column I3 (top temperature 65 ℃, bottom temperature 105 ℃). At ℃, 45 trays, reflux ratio 3.5), light components (methanol, aldehydes, ketones, and esters, purity ≥99%) were collected from the top of the column, and fusel oil vapor with 96.8% ethanol content was collected from the side stream. The bottom liquid (containing 28.1% n-propanol and 20.4% n-butanol) entered vacuum distillation column 4 (operating pressure -0.09 MPa, top temperature 58 ℃, bottom temperature 80 ℃, 65 trays, reflux ratio 10) to obtain ethanol with 99.7% purity. After the bottom liquid was separated from atmospheric distillation column II 5 and atmospheric distillation column III 6 (99.8% n-propanol was collected from the top and 99.5% n-butanol was collected from the bottom), the yield of n-propanol increased to 97.1%, n-butanol to 96.3%, the ethanol recovery rate reached 95.6%, and the COD concentration in the wastewater decreased to 198 mg / L.
[0050] In the comparative example, fusel oil with a processing capacity of 5000 kg / h was used as raw material (with the same composition as in Example 1). Separation was performed using a conventional multi-tower azeotropic distillation process, with the specific steps as follows:
[0051] First, dehydration is carried out using an atmospheric pressure dehydration tower. The tower operates at atmospheric pressure with a top temperature of 100℃ (the azeotrope contains ethanol / water / methanol, purity 85%) and a bottom temperature of 120℃. At ℃, with 60 trays and a reflux ratio of 8, the intermediate product after dehydration had a water content of 8.5%. The intermediate product was then fed into an ethanol distillation column, operated at atmospheric pressure, with a top temperature of 78℃ (ethanol-water azeotrope, ethanol purity 92.3%), 50 trays, and a reflux ratio of 10. The side stream could not efficiently extract high-purity ethanol, and the top ethanol yield was 82.5% with a purity of 95%. A large amount of methanol and aldehyde / ketone impurities remained in the bottom column. The bottom liquid was then fed into an atmospheric distillation column, with a top temperature of 97℃ (n-propanol purity 88.4%) and a bottom temperature of 118℃ (n-butanol purity 85.7%), 50 trays, and a reflux ratio of 6. The total yield was 78.6% for n-propanol and 72.3% for n-butanol. The COD in the wastewater was as high as 1200 mg / L.
[0052] A comparison of Example 1 and the comparative example shows that the water content of the intermediate product after dehydration in the comparative example is still as high as 8.5%, which is significantly worse than the membrane separation dehydration effect of Example 1. This leads to the difficulty in efficient separation of the water-ethanol azeotropic effect in the subsequent ethanol distillation column, reducing the ethanol yield, and leaving a large amount of methanol and aldehyde / ketone impurities in the column bottom. Furthermore, the final total yield of n-propanol and n-butanol is only 78.6% and 72.3%, respectively, which is significantly lower than 96.5% and 95.8% in Example 1. The COD content in the treated wastewater is also high. This fully demonstrates that Example 1 achieves a breakthrough improvement in product purity, yield, energy consumption, and environmental protection through membrane separation-reduced pressure distillation coupling and thermal integration technology.
[0053] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that the above embodiments do not limit this utility model in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this utility model.
Claims
1. A device for separating and purifying of fusel oil in a Fischer-Tropsch synthesis, characterized in that, include: A pressurized distillation column (1) is used to perform pressurized distillation on fusel oil to remove acids, C4+ alcohols and some n-butanol; The membrane separator (2) is connected to the top outlet of the pressurized distillation column (1) and is used to dehydrate the top steam of the column. Atmospheric distillation column I (3) is connected to the bottom outlet of membrane separator (2) for removing light components; The vacuum distillation column (4) is connected to the bottom outlet of the atmospheric distillation column I (3) and is used to remove propanol and butanol from the bottom liquid of the column. Atmospheric distillation column II (5) is connected to the bottom outlet of vacuum distillation column (4) and is used to remove isopropanol from the bottom liquid of the column; Atmospheric distillation column III (6) is connected to the bottom outlet of atmospheric distillation column II (5) and is used to separate n-propanol and n-butanol in the bottom liquid of the column.
2. The device for separating and purifying fusel oil in a Fischer-Tropsch synthesis according to claim 1, characterized in that, It also includes a preheater (7) connected to a pressurized distillation column (1) for preheating fusel oil.
3. The apparatus for separating and refining fusel oils in Fischer-Tropsch synthesis according to claim 1, 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 module; the permeate condenser (8) is connected to a permeate tank (9) for storing permeate.
4. The apparatus for separating and refining fusel oils in Fischer-Tropsch synthesis according to claim 1, characterized in that, The top of the vacuum distillation column (4) is connected to the vacuum distillation column condenser (10) for condensing the top steam of the column; the outlet of the vacuum distillation column condenser (10) is connected to the top of the vacuum distillation column (4) and the ethanol storage tank (11) respectively, for returning part of the condensed liquid back into the column and taking out part of the ethanol product.
5. The apparatus for separating and refining fusel oils in Fischer-Tropsch synthesis according to claim 1, characterized in that, The pressurized distillation column (1), atmospheric distillation column I (3), vacuum distillation column (4), atmospheric distillation column II (5) and atmospheric distillation column III (6) are all connected to a reboiler (12).
6. The apparatus for separating and refining fusel oils in Fischer-Tropsch synthesis according to claim 5, characterized in that, It also includes a mixing tank (13), the inlet of which is connected to the reboilers (12) of the pressurized distillation column (1), the atmospheric distillation column I (3), the atmospheric distillation column II (5) and the atmospheric distillation column III (6), and the outlet is connected to the reboiler (12) of the vacuum distillation column (4), which is used to collect the steam condensate in the reboilers (12) of the pressurized distillation column (1), the atmospheric distillation column I (3), the atmospheric distillation column II (5) and the atmospheric distillation column III (6) and send it into the reboiler (12) of the vacuum distillation column (4).