Fusel separation system for butanol purification

Abstract

The present invention relates to the technical field of chemical separation, and discloses a fusel separation system for butanol purification, the fusel separation system comprises: a first pretreatment tower for separating a preheated raw material, the tower top of the first pretreatment tower is provided with a condensation system for separating mixed steam of methanol, ethanol and n-butanol, and the mixed steam is used for separating the mixed steam of methanol, ethanol and n-butanol; the tower kettle is heated through a first reboiler, and the temperature in the tower is maintained to promote evaporation of light components; and the first preheater is configured before the raw materials enter the pretreatment tower and is used for heating the raw materials to a boiling point temperature so as to ensure the efficiency of a subsequent separation process. By utilizing a multi-stage separation process, the purity of butanol is effectively improved, a high-purity butanol product is obtained, the reboiler and the preheater in the system are reasonable in design, low-pressure steam and a heat source are fully utilized, and particularly, due to the heat recovery design between the azeotropic separation tower and the product refining tower, the whole system has relatively high heat efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of chemical separation, in particular to a fusel alcohol separation system for purifying butanol. Background Art

[0002] Butanol is an important bulk chemical widely used in the chemical and fuel fields. In recent years, butanol has attracted much attention due to its potential as an alternative fuel. Compared with traditional fuel ethanol, butanol has a longer carbon chain structure and a higher carbon-hydrogen ratio, so it has a higher calorific value, lower volatility, and better gasoline compatibility. In fuel applications, butanol's physical and chemical properties make it an alternative fuel with significant advantages. In addition, butanol has lower water solubility, which reduces corrosiveness to the fuel system and can improve the combustion efficiency of the engine.

[0003] However, the industrial production of butanol faces certain bottlenecks, especially in the biosynthesis pathway. The separation process of biobutanol is a link with high energy consumption. It is estimated that in traditional processes, the separation cost of biobutanol accounts for more than 14% of the total production cost, second only to the cost of raw materials. The high cost of butanol separation has become one of the main factors restricting its industrial application. Therefore, how to reduce the energy consumption in the separation process while ensuring the purity of butanol has become a key issue in the butanol purification process.

[0004] Existing butanol purification technology mostly adopts distillation process, including preliminary separation and refining process. A series of separation towers (such as pretreatment tower, azeotropic separation tower and refining tower) and auxiliary equipment such as reboiler and condenser are used in the typical process flow. However, in the traditional process, due to insufficient utilization of heat source and low heat recovery efficiency, the energy consumption in the separation process remains high. In addition, the single reflux design is often difficult to achieve accurate material balance within the system, resulting in the purification efficiency and system output rate of the butanol product being limited, further increasing the production cost. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a fusel alcohol separation system for butanol purification, which solves the problem that the existing equipment has high energy consumption in the separation process due to insufficient utilization of heat sources and low heat recovery efficiency.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: a fusel alcohol separation system for butanol purification, comprising:

[0007] A first pretreatment tower is used to separate the preheated raw materials. The top of the first pretreatment tower is provided with a condensation system to separate the mixed vapor of methanol, ethanol and n-butanol. The bottom of the tower is heated by a first reboiler to maintain the temperature in the tower to promote the evaporation of light components.

[0008] The first preheater is arranged before the raw material enters the pretreatment tower and is used to heat the raw material to the boiling point to ensure the efficiency of the subsequent separation process;

[0009] A first condenser is connected to the top of the first pretreatment tower, and uses circulating water as a cold source to condense the methanol, ethanol and n-butanol vapors rising from the top of the tower into a liquid phase and then pass it into a first reflux tank;

[0010] A first reflux tank is used to store the condensed liquid, wherein part of the liquid is returned to the top of the pretreatment tower as reflux liquid through a first reflux pump, and the rest is discharged as waste liquid;

[0011] an azeotropic separation tower, receiving a mixture of heavy phase water and n-butanol extracted from the side line of the first pretreatment tower, for further separating the azeotrope of n-butanol and water, and discharging waste water from the bottom of the tower;

[0012] The product refining tower is used to receive the mixture of n-butanol and n-pentanol produced from the kettle of the pretreatment tower, to purify it to obtain a high-purity butanol product, and to discharge n-pentanol from the bottom of the tower.

[0013] Preferably, a side line outlet is provided in the middle of the first pretreatment tower for producing a liquid mixture of water and n-butanol. The liquid mixture is sequentially passed through a second preheater for heat exchange and a second condenser for condensation, and then passed into a phase separation tank to achieve liquid phase separation.

[0014] Preferably, the phase separation tank is configured to phase separate the mixed liquid of water and n-butanol, the light phase in the phase separation tank is pumped into the middle and lower part of the first pretreatment tower through the first extraction pump, and the heavy phase in the phase separation tank is pumped into the azeotropic separation tower through the second extraction pump to achieve effective phase separation and resource recovery.

[0015] Preferably, a third condenser is provided at the top of the azeotropic separation tower, and the mixed vapor of n-butanol and water rising from the top of the condensation tower is condensed to pass the condensed liquid into the second reflux tank, and a part of the liquid is returned to the top of the azeotropic separation tower by a reflux pump, and the other part of the liquid is returned to the second pretreatment tower to maintain the material balance in the tower.

[0016] Preferably, the kettle of the azeotropic separation tower is provided with two reboilers, one of which uses low-pressure steam as a heat source, and the other reboiler uses the top steam of the product refining tower as a heat source, so as to achieve energy recovery and improve the thermal efficiency of the system.

[0017] Preferably, the bottom of the azeotropic separation tower is provided with a third extraction pump for pumping the waste water at the bottom of the tower into a third preheater for heat exchange with the raw material, and the waste water after heat exchange is discharged from the extraction boundary area.

[0018] Preferably, the mixture of n-butanol and n-pentanol produced from the kettle of the first pretreatment tower is pumped into a product refining tower through a fourth production pump, and the product refining tower is used to further purify butanol and separate n-pentanol.

[0019] Preferably, azeotropic vapor of butanol and water is generated at the top of the product refining tower, and the azeotropic vapor is passed into the second reboiler of the azeotropic separation tower for heat recovery, and is condensed into a liquid phase and then passed into the third reflux tank.

[0020] Preferably, an azeotropic vapor of butanol and water is generated at the top of the product refining tower, the azeotropic vapor is passed into the second reboiler of the azeotropic separation tower for heat recovery, and is condensed into a liquid phase and then passed into a third reflux tank, the third reflux tank refluxes a part of the liquid to the top of the product refining tower through a second reflux pump, and the other part is extracted as a high-purity butanol product.

[0021] Preferably, the product refining tower is provided with a storage tower bottom for discharging the n-pentanol through a storage tower bottom outlet as one of the by-products separated by the system for industrial recovery and utilization.

[0022] The present invention provides a fusel alcohol separation system for butanol purification, which has the following beneficial effects:

[0023] 1. The present invention can efficiently separate components such as methanol, ethanol, n-butanol and n-amyl alcohol through the combination of pretreatment tower, azeotropic separation tower and product refining tower, thereby ensuring the separation purity of fusel alcohol. Utilize multi-stage separation process, effectively improve the purity of butanol, obtain high-purity butanol product, the reboiler and preheater in the system are reasonably designed, make full use of low-pressure steam and heat source, particularly the heat recovery design between azeotropic separation tower and product refining tower, so that the whole system has higher thermal efficiency. This energy recovery mechanism improves the overall thermal efficiency of the system while reducing energy consumption, helps to save energy and reduce operating costs.

[0024] 2. The present invention taps the potential for heat extraction multiple times, maximizes the use of waste heat, and saves energy and reduces consumption. A preheater is added to make the feed temperature of each tower close to the bubble point temperature. The process is optimized, the process parameters are adjusted, and the steam heat source of the azeotropic separation tower reboiler is reduced. Instead, the waste heat of the steam at the top of the product refining tower is used, which not only saves energy consumption, but also reduces the equipment investment and circulating cooling water consumption caused by the cooling of the refined butanol product.

[0025] 3. The present invention provides multiple reflux tanks and reflux pumps, and the material balance in each tower section is precisely controlled. This multi-point reflux design improves the separation efficiency of the system, enables components such as n-butanol and water to be effectively separated, reduces the loss of butanol, and improves the output rate of the system. The system is designed with a variety of extraction pumps, phase separation tanks and preheaters, which are easy to adjust according to changes in raw materials and process conditions, and can more flexibly adapt to different requirements for separation and purification of fusel alcohols, thereby improving the operational stability and production efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention.

[0027] Among them, 1. the first preheater; 2. the first pretreatment tower; 3. the first condenser; 4. the first reflux tank; 5. the first reboiler; 6. the first reflux pump; 7. the second reflux pump; 8. the storage tower kettle; 9. the second preheater; 10. the second condenser; 11. the phase separation tank; 12. the first production pump; 13. the second production pump; 14. the azeotropic separation tower; 15. the third condenser; 16. the second reflux tank; 17. the third reflux tank; 18. the second pretreatment tower; 19. the product refining tower; 20. the third production pump; 21. the third preheater; 22. the production boundary; 23. the fourth production pump; 24. the second reboiler. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Please see attached Figure 1 The embodiment of the present invention provides a fusel alcohol separation system for butanol purification, comprising:

[0030] The first pretreatment tower 2 is used to separate the preheated raw materials. The top of the first pretreatment tower 2 is provided with a cooling system to separate the mixed vapor of methanol, ethanol and n-butanol. The bottom of the tower is heated by the first reboiler 5 to maintain the temperature in the tower to promote the evaporation of the light component.

[0031] The first preheater 1 is arranged before the raw material enters the pretreatment tower and is used to heat the raw material to the boiling point to ensure the efficiency of the subsequent separation process;

[0032] The first condenser 3 is connected to the top of the first pretreatment tower 2, and uses circulating water as a cold source to condense the methanol, ethanol and n-butanol vapors rising from the top of the tower into a liquid phase and then pass it into the first reflux tank 4;

[0033] A first reflux tank 4 is used to store the condensed liquid, wherein part of the liquid is returned to the top of the pretreatment tower as reflux liquid through a first reflux pump 6, and the rest is discharged as waste liquid;

[0034] Azeotropic separation tower 14 receives the mixture of heavy phase water and n-butanol extracted from the side line of the first pretreatment tower 2, is used to further separate the azeotrope of n-butanol and water, and discharge waste water from the bottom of the tower;

[0035] The product refining tower 19 is used to receive the mixture of n-butanol and n-pentanol produced from the kettle of the pretreatment tower, to purify the mixture to obtain a high-purity butanol product, and to discharge n-pentanol from the bottom of the tower.

[0036] In one embodiment, the raw material is first preheated to a bubble point temperature of about 75 to 90°C by the first preheater 1 to ensure that the best separation state is achieved when entering the separation system. The preheated raw material enters the first pretreatment tower 2, and the tower kettle is heated to about 125 to 130°C by the first reboiler 5 to maintain the temperature in the tower and promote the evaporation of light components such as methanol, ethanol and n-butanol. In this process, the mixed vapor of methanol, ethanol and n-butanol is condensed into a liquid phase by the first condenser 3, with a condensation temperature of about 50 to 60°C, and is introduced into the first reflux tank 4. The condensed liquid is stored in the first reflux tank 4, and a part of the liquid is sent back to the top of the first pretreatment tower 2 as reflux liquid through the first reflux pump 6, with a reflux ratio of about 8 to 10 to improve the separation efficiency, and the rest is discharged from the system as waste liquid. The setting of this reflux process ensures the effective separation of light components in the tower and improves the purification effect of the system. In the middle of the pretreatment tower, a heavy phase mixture containing water and n-butanol is produced through the side line production port and transported to the azeotropic separation tower 14. In the azeotropic separation tower, the azeotrope formed by n-butanol and water is further separated, and the azeotropic steam of n-butanol and water at the top of the tower is refluxed after condensation, and the condensation temperature is about 60-80°C, and waste water is discharged from the bottom of the tower. This step effectively removes water and retains the butanol component through the design of azeotropic separation, laying the foundation for the subsequent refining process. The pretreatment tower bottom extracts a mixture of n-butanol and n-pentanol, and the mixture is pumped into the product refining tower 19 by the fourth extraction pump. The product refining tower further purifies n-butanol through the refining process to ensure the high purity of the butanol product. At the same time, at the bottom of the product refining tower, n-pentanol is separated and extracted as a by-product for other industrial purposes or further processing. In the heat cycle between the product refining tower and the azeotropic separation tower, the system effectively utilizes the azeotropic steam of butanol and water. By introducing the azeotropic steam at the top of the product refining tower 19 into the reboiler of the azeotropic separation tower 14 for heat recovery, efficient waste heat utilization is achieved, reducing additional steam demand. This design significantly improves the energy efficiency of the system and reduces the energy consumption and operating costs of the system.

[0037] A side line outlet is provided in the middle of the first pretreatment tower 2 for producing a liquid mixture of water and n-butanol. The liquid mixture is sequentially passed through the second preheater 9 for heat exchange and the second condenser 10 for condensation, and then passed into the phase separation tank 11 to achieve liquid phase separation.

[0038] In one embodiment, a side line outlet is provided in the middle of the first pretreatment tower 2 for extracting a liquid mixture containing water and n-butanol. The extracted liquid mixture of water and n-butanol first enters the second preheater 9. The second preheater 9 uses the raw materials in the system for heat exchange to gradually reduce the temperature of the mixture. In this process, the design of the second preheater 9 ensures that the heat in the mixture can be effectively recovered and transferred to the raw materials, thereby improving the overall energy utilization rate. After heat exchange in the second preheater 9, the liquid mixture continues to flow into the second condenser 10. The second condenser 10 uses a cold source such as cooling water to cool the liquid. The phase mixture is further condensed to 40-50° C., and the condensed liquid is introduced into the phase separation tank 11. Through the static phase separation process, the light phase and the heavy phase are fully separated. n-Butanol floats on the upper layer as the light phase, and water sinks to the lower layer as the heavy phase, thereby realizing physical phase separation. After the light phase n-Butanol and the heavy phase water in the phase separation tank 11 are separated, they are transported to different parts of the system through different extraction pumps respectively. The light phase is returned to the middle and lower parts of the pretreatment tower by the extraction pump to ensure the recovery of butanol and reduce its loss in the separation process; and the heavy phase is transported to the azeotropic separation tower by another extraction pump for further fine separation.

[0039] The phase separation tank 11 is configured to separate the mixed liquid of water and n-butanol into phases. The light phase in the phase separation tank 11 enters the middle and lower part of the first pretreatment tower 2 through the first extraction pump 12, and the heavy phase in the phase separation tank 11 enters the azeotropic separation tower 14 through the second extraction pump 13 to achieve effective phase separation and resource recovery.

[0040] In one embodiment, the heavy phase water in the phase separation tank 11 is transported to the azeotropic separation tower 14 through the second extraction pump 13. In the azeotropic separation tower, water and a small amount of residual n-butanol are further separated. Through the azeotropic separation technology, n-butanol can be recovered at the top of the tower, and waste water is discharged from the bottom of the tower. This step further purifies the n-butanol and ensures the recovery efficiency of the system and the purity of butanol.

[0041] A third condenser 15 is provided at the top of the azeotropic separation tower 14. The mixed vapor of n-butanol and water rising from the top of the condensation tower is condensed, and the condensed liquid is passed into the second reflux tank 16. A part of the liquid is returned to the top of the azeotropic separation tower 14 by a reflux pump, and the other part of the liquid is returned to the second pretreatment tower 18 to maintain the material balance in the tower.

[0042] In one embodiment, the top vapor of the azeotropic separation tower 14 contains a mixture of n-butanol and water, which is condensed into liquid through the third condenser 15, and the condensation temperature is about 60-80°C. The condensation process uses a circulating cold source to quickly cool the vapor to a liquid phase, thereby achieving the purpose of separating water and n-butanol. The condensed liquid enters the second reflux tank 16, in which the condensed liquid is divided into two parts by a reflux pump, and a part of the liquid refluxes to the top of the azeotropic separation tower 14. This part of the reflux liquid provides a sufficient reflux ratio for the azeotropic separation tower, and the reflux ratio is about 0.2-0.5, which ensures the stable separation of the materials in the tower, enhances the separation effect of water and n-butanol, and maintains the material circulation in the tower.

[0043] The kettle of the azeotropic separation tower 14 is provided with two reboilers, one of which uses low-pressure steam as a heat source, and the other reboiler uses the top steam of the product refining tower 19 as a heat source, so as to achieve energy recovery and improve the thermal efficiency of the system.

[0044] In one embodiment, the heat sources of the two reboilers are used in combination to balance the temperature in the bottom of the azeotropic separation tower, so that the bottom temperature is stabilized at about 100-105°C, providing a stable operating temperature environment. This temperature control not only improves the separation efficiency of the materials in the tower, but also effectively controls the evaporation rate of the azeotrope of butanol and water, thereby achieving accurate component separation and ensuring the separation effect of the system.

[0045] The bottom of the azeotropic separation tower 14 is provided with a third extraction pump 20 for pumping the waste water at the bottom of the tower into a third preheater 21 for heat exchange with the raw material. The waste water after heat exchange is discharged from the system from the extraction boundary area 22.

[0046] In one embodiment, the wastewater in the bottom of the azeotropic separation tower 14 is extracted by the third extraction pump 20 and transported to the third preheater 21 to heat the raw materials to 50-60° C. The function of the pump is to pressurize and transport the wastewater at the bottom of the tower to ensure that the wastewater can smoothly enter the preheater and undergo subsequent heat exchange processes.

[0047] The mixture of n-butanol and n-pentanol extracted from the bottom of the first pretreatment tower 2 is pumped into the product refining tower 19 through the fourth extraction pump 23. The product refining tower 19 is used to further purify butanol and separate n-pentanol.

[0048] In one embodiment, in the product refining tower 9, the mixture of n-butanol and n-pentanol is subjected to appropriate heating and distillation processes and heated to about 135-140° C. Due to the different boiling points of n-butanol and n-pentanol, n-butanol evaporates preferentially and rises in the tower to enter the top area, while n-pentanol is retained in the bottom of the tower as a heavy component, thereby achieving effective separation of the components.

[0049] Azeotropic vapor of butanol and water is generated at the top of the product refining tower 19 , and the azeotropic vapor is passed into the second reboiler 24 of the azeotropic separation tower 14 for heat recovery, and is condensed into a liquid phase and then passed into the third reflux tank 17 .

[0050] In one embodiment, at the top of the product refining tower 19, azeotropic vapor of butanol and water is generated and guided to the second reboiler 24 of the azeotropic separation tower 14 to be condensed to about 90-100° C. By directly introducing the azeotropic vapor into the second reboiler, the loss of vapor is avoided and the subsequent heat recovery is facilitated.

[0051] Azeotropic vapor of butanol and water is generated at the top of the product refining tower 19, and the azeotropic vapor is passed into the second reboiler 24 of the azeotropic separation tower 14 for heat recovery, and is condensed into a liquid phase and then passed into the third reflux tank 17. The third reflux tank 17 refluxes part of the liquid to the top of the product refining tower 19 through the second reflux pump 7, and the other part is extracted as a high-purity butanol product.

[0052] In one embodiment, the condensate tank in the third reflux tank 17 is divided into two parts by the second reflux pump 7, one part is returned to the top of the product refining tower 19 as reflux liquid to maintain the separation efficiency in the tower and the high purity of butanol; the other part of the liquid is extracted and collected as the final high-purity butanol product, and the reflux ratio is about 0.6 to 0.8.

[0053] The product refining tower 19 is provided with a storage tower bottom 8, and the n-pentanol is discharged through the storage tower bottom 8 outlet as one of the by-products separated by the system for industrial recovery and utilization.

[0054] Working principle: The raw materials first enter the first preheater and are heated to the bubble point temperature so that the light components can be more easily separated in the subsequent pretreatment tower. The preheated raw materials enter the pretreatment tower, and the tower kettle is heated by the first reboiler to maintain the temperature in the tower, thereby promoting the evaporation of light components such as methanol, ethanol and n-butanol. After separation, these light component vapors are condensed through the first condenser and enter the first reflux tank, of which a part of the liquid refluxes to the top of the tower to improve the separation efficiency, and the remaining liquid is discharged as a waste liquid system. A side line production port is provided in part of the pretreatment tower to produce a liquid mixture containing water and n-butanol. The mixture enters the second preheater for heat exchange with the raw material, and is subsequently condensed into a liquid phase through the second condenser and enters the phase separation tank, wherein the light phase is returned to the middle and lower part of the pretreatment tower through the first extraction pump, and the heavy phase is sent to the azeotropic separation tower through the second extraction pump. In the azeotropic separation tower, the azeotrope of the heavy phase water and n-butanol is further separated in the tower, and the mixed vapor of n-butanol and water at the top of the tower is condensed through the third condenser and passed into the second reflux tank. Part of the liquid in the reflux tank is refluxed to the top of the azeotropic separation tower to maintain the material balance in the tower, and the other part of the liquid is returned to the second pretreatment tower. The kettle of the azeotropic separation tower is provided with a first reboiler and a second reboiler, so as to utilize low-pressure steam and the top steam of the product refining tower for heating; the waste water of the kettle is transported to the third preheater through the third extraction pump for heat exchange with the raw material and then discharged from the extraction boundary area; the mixture of n-butanol and n-pentanol extracted from the kettle of the pretreatment tower is transported to the product refining tower through the fourth extraction pump, and is further purified in the refining tower to obtain a high-purity butanol product; at the same time, the azeotropic steam of butanol and water generated at the top of the tower enters the second reboiler of the azeotropic separation tower for heat recovery to save system energy consumption; n-pentanol can be discharged from the extraction outlet of the kettle of the refining tower as a by-product for further utilization; a part of the top condensate of the product refining tower is refluxed to the top of the tower through the third reflux tank and the second reflux pump to ensure the separation effect in the tower, and the other part is extracted as a high-purity butanol product for industrial application; the whole system realizes high-quality butanol purification through an efficient separation process.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A fusel alcohol separation system for butanol purification, characterized in that: include: A first pretreatment tower (2) is used to separate the preheated raw materials. The top of the first pretreatment tower (2) is provided with a condensation system to separate the mixed vapor of methanol, ethanol and n-butanol. The bottom of the tower is heated by a first reboiler (5) to maintain the temperature in the tower to promote the evaporation of light components. A first preheater (1) is arranged before the raw material enters the pretreatment tower and is used to heat the raw material to a boiling point to ensure the efficiency of the subsequent separation process; A first condenser (3) is connected to the top of the first pretreatment tower (2), and uses circulating water as a cold source to condense the methanol, ethanol and n-butanol vapors rising from the top of the tower into a liquid phase, which is then passed into a first reflux tank (4); A first reflux tank (4) is used to store the condensed liquid, wherein part of the liquid is returned to the top of the pretreatment tower as reflux liquid through a first reflux pump (6), and the rest is discharged as waste liquid; an azeotropic separation tower (14), receiving the mixture of heavy phase water and n-butanol extracted from the side line of the first pretreatment tower (2), for further separating the azeotropic product of n-butanol and water, and discharging waste water from the bottom of the tower; The product refining tower (19) is used to receive the mixture of n-butanol and n-pentanol extracted from the kettle of the pretreatment tower, purify it to obtain a high-purity butanol product, and discharge n-pentanol from the bottom of the tower.

2. A fusel alcohol separation system for butanol purification according to claim 1, characterized in that: A side line outlet is provided in the middle of the first pretreatment tower (2) for producing a liquid mixture of water and n-butanol. The liquid mixture is sequentially passed through a second preheater (9) for heat exchange and a second condenser (10) for condensation, and then passed into a phase separation tank (11) to achieve liquid phase separation.

3. A fusel alcohol separation system for butanol purification according to claim 2, characterized in that: The phase separation tank (11) is configured to separate the mixed liquid of water and n-butanol into phases, the light phase in the phase separation tank (11) enters the middle and lower part of the first pretreatment tower (2) through the first extraction pump (12), and the heavy phase in the phase separation tank (11) enters the azeotropic separation tower (14) through the second extraction pump (13), so as to achieve effective phase separation and resource recovery.

4. A fusel alcohol separation system for butanol purification according to claim 3, characterized in that: The top of the azeotropic separation tower (14) is provided with a third condenser (15), which condenses the mixed vapor of n-butanol and water rising from the top of the tower, passes the condensed liquid into the second reflux tank (16), and a part of the liquid is returned to the top of the azeotropic separation tower (14) by a reflux pump, and the other part of the liquid is returned to the second pretreatment tower (18) to maintain the material balance in the tower.

5. A fusel alcohol separation system for butanol purification according to claim 4, characterized in that: The kettle of the azeotropic separation tower (14) is provided with two reboilers, one of which uses low-pressure steam as a heat source, and the other reboiler uses the top steam of the product refining tower (19) as a heat source, so as to achieve the purpose of energy recovery and improve the thermal efficiency of the system.

6. A fusel alcohol separation system for butanol purification according to claim 5, characterized in that: The bottom of the azeotropic separation tower (14) is provided with a third extraction pump (20) for pumping the waste water at the bottom of the tower into a third preheater (21) for heat exchange with the raw material, and the waste water after heat exchange is discharged from the system through the extraction boundary area (22).

7. A fusel alcohol separation system for butanol purification according to claim 6, characterized in that: The mixture of n-butanol and n-pentanol extracted from the bottom of the first pretreatment tower (2) is pumped into the product refining tower (19) through the fourth extraction pump (23). The product refining tower (19) is used to further purify butanol and separate n-pentanol.

8. A fusel alcohol separation system for butanol purification according to claim 7, characterized in that: Azeotropic vapor of butanol and water is generated at the top of the product refining tower (19), and the azeotropic vapor is passed into the second reboiler (24) of the azeotropic separation tower (14) for heat recovery, and is condensed into a liquid phase and then passed into the third reflux tank (17).

9. A fusel alcohol separation system for butanol purification according to claim 8, characterized in that: Azeotropic vapor of butanol and water is generated at the top of the product refining tower (19), and the azeotropic vapor is passed into the second reboiler (24) of the azeotropic separation tower (14) for heat recovery, and is condensed into a liquid phase and then passed into the third reflux tank (17). The third reflux tank (17) refluxes a portion of the liquid to the top of the product refining tower (19) through a second reflux pump (7), and the other portion is extracted as a high-purity butanol product.

10. A fusel alcohol separation system for butanol purification according to claim 9, characterized in that: The product refining tower (19) is provided with a storage tower kettle (8) in which the n-pentanol is discharged through the outlet of the storage tower kettle (8) as one of the by-products separated by the system for industrial recovery and utilization.

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