Device and method for separating and purifying tetrahydrofuran and n-butanol from gamma-butyrolactone production industrial waste liquid

Abstract

The invention belongs to the technical field of chemical separation, and particularly relates to a device and a method for separating and purifying tetrahydrofuran and n-butyl alcohol from gamma-butyrolactone production industrial waste liquid. The device comprises a pre-separation tower, an n-butyl alcohol refining tower, a water treatment tower, a butanone removal tower, a tetrahydrofuran extraction tower and a solvent recovery tower, the quality purity of tetrahydrofuran separated by adopting the device can reach 99.95% or above, the recovery rate can reach 94.3% or above, the quality purity of n-butyl alcohol can reach 99.5% or above, and the recovery rate can reach 99% or above. According to the method, a separation method combining extractive distillation and heterogeneous azeotropic distillation is adopted, an ionic liquid 1-butyl-3-methylimidazole acetate is used as an extraction agent for extractive distillation separation of a tetrahydrofuran-water mixture, and a mixture of n-butanol and water is separated through heterogeneous azeotropic distillation without adding an entrainer. The process provided by the invention plays an important role in environmental protection and clean production, and can realize low-energy-consumption, clean and efficient separation of the azeotropic system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical separation technology, and particularly relates to a device and method for separating and purifying tetrahydrofuran and n-butanol from γ-butyrolactone production industrial waste liquid. BACKGROUND

[0002] Tetrahydrofuran and n-butanol are two extremely important basic chemical raw materials, which have an irreplaceable core role in many industries such as medicine, chemical industry, pesticide, paint, electronics and energy. As a medium polar aprotic solvent, tetrahydrofuran is widely used as a key solvent for polymerization reactions (such as the production of polytetrahydrofuran), and is also an ideal medium for metal organic reactions such as Grignard reagent, and plays an important role in the field of drug synthesis and the preparation of lithium battery electrode slurry. N-butanol is not only a widely used organic solvent, but also an important precursor for the synthesis of various chemical products. For example, it is the main raw material for manufacturing plasticizers (such as dibutyl phthalate) and paint solvents butyl acetate. In addition, n-butanol also plays a crucial role in the preparation of pharmaceutical intermediates, as an extractant, and in the field of fuel additives. Its industry chain is extended, and the downstream products are rich, which highlights its basic position in modern chemical industry.

[0003] In actual chemical production, mixed industrial waste liquid containing tetrahydrofuran, water and n-butanol and other substances is often produced. Due to the easy formation of azeotropes between these components, traditional single rectification method is difficult to achieve effective separation, which will result in low recovery rate and purity of tetrahydrofuran and n-butanol. Therefore, it is of great industrial application value to develop an efficient and energy-saving separation and purification method.

[0004] Patent (CN102911139A) relates to a device and method for separating tetrahydrofuran-ethanol azeotrope by extractive distillation. The application results show that the recovery rate of tetrahydrofuran product is only 90%.

[0005] Patent (CN117839247A) relates to a system and method for continuous separation of n-butanol and water azeotrope system by rectification-membrane separation. However, due to the involvement of membrane separation, special equipment such as membrane assembly, membrane shell, precision feed pump, vacuum system (if using pervaporation) is added. And the membrane itself is currently high in cost, which may lead to poor economic efficiency in the whole separation process.

[0006] Patent (CN117304145A) relates to a method for separating tetrahydrofuran / methanol / water ternary mixture by reactive pressure swing distillation. However, its system is highly complex and difficult to operate: the process is coupled with reaction distillation, pressure swing distillation and heat integration three operation units, the control loop interferes with each other, the anti-vibration ability is poor, at the same time, flammable and explosive ethylene oxide needs to be introduced as a reaction raw material, which increases the raw material cost and storage risk, and forces the product structure to turn to ethylene glycol co-production, lacking flexibility. SUMMARY

[0007] In view of the problems and deficiencies in the prior art, the purpose of the present application is to provide a device and method for separating and purifying tetrahydrofuran and n-butanol from gamma-butyrolactone production industrial waste liquid.

[0008] To achieve the above purpose, the present application adopts the following technical scheme:

[0009] The first aspect of the present application provides a device for separating and purifying tetrahydrofuran and n-butanol from gamma-butyrolactone production industrial waste liquid, which comprises a pre-separation tower, the pre-separation tower is provided with a feed inlet, the pre-separation tower top outlet is connected to the feed inlet of a butanone removal tower, the butanone removal tower top outlet is connected to the feed inlet of a tetrahydrofuran extraction tower, the tetrahydrofuran extraction tower bottom outlet is connected to the feed inlet of a solvent recovery tower, the solvent recovery tower bottom outlet is connected to the upper feed inlet of the tetrahydrofuran extraction tower, and the tetrahydrofuran extraction tower top outlet is used to extract tetrahydrofuran product; the pre-separation tower bottom outlet is connected to a mixer, the mixer is connected to a phase separator, one outlet of the phase separator is connected to the feed inlet of an n-butanol refining tower, the other outlet of the phase separator is connected to the feed inlet of a water treatment tower, the n-butanol refining tower top outlet and the water treatment tower top outlet are both connected to the mixer, and the n-butanol refining tower bottom outlet is used to extract n-butanol product.

[0010] Further, the pipeline connected to the feed inlet of the pre-separation tower is provided with a preheater, the pipeline connected to the mixer and the phase separator is provided with a condenser, and the pipeline connected to the solvent recovery tower bottom outlet and the upper feed inlet of the tetrahydrofuran extraction tower is provided with a condenser.

[0011] Further, the pipeline connected to the pre-separation tower top outlet and the feed inlet of the butanone removal tower is provided with a centrifugal pump, the pipeline connected to the butanone removal tower top outlet and the feed inlet of the tetrahydrofuran extraction tower is provided with a centrifugal pump, the pipeline connected to the phase separator and the feed inlet of the n-butanol refining tower is provided with a centrifugal pump, and the pipeline connected to the phase separator and the feed inlet of the water treatment tower is provided with a centrifugal pump.

[0012] The second aspect of the present application provides a method for separating and purifying tetrahydrofuran and n-butanol from gamma-butyrolactone production industrial waste liquid by using the device of the first aspect, which comprises the following steps:

[0013] S1: The γ-butyrolactone production industrial waste liquid is preheated and then introduced into a pre-separation column for rectification, and a mixed solution containing tetrahydrofuran, water, methanol and butanone is obtained at the top of the column, and a mixed solution containing n-butanol and water is obtained at the bottom of the column;

[0014] S2: The mixed solution at the top of the pre-separation column in step S1 is introduced into a butanone removal column for rectification, and a mixed solution containing tetrahydrofuran, water and methanol is obtained at the top of the column, and a butanone waste liquid is obtained at the bottom of the column;

[0015] S3: The mixed solution at the top of the butanone removal column in step S2 is introduced into a tetrahydrofuran extraction column, and ion liquid is used to extract tetrahydrofuran in the mixed solution, and tetrahydrofuran product is obtained at the top of the column, and a mixed solution containing ion liquid, water and methanol is obtained at the bottom of the column; the mixed solution at the bottom of the tetrahydrofuran extraction column is introduced into a solvent recovery column, and methanol waste liquid is obtained at the top of the solvent recovery column, and ion liquid is obtained at the bottom of the column, and the ion liquid is recycled to the tetrahydrofuran extraction column;

[0016] S4: The mixed solution obtained at the bottom of the pre-separation column in step 1 is introduced into a phase separator, and the phase separator separates the mixed solution into an organic phase and an aqueous phase, the aqueous phase is introduced into a water treatment column, and the organic phase is introduced into an n-butanol rectification column, and n-butanol product is obtained at the bottom of the n-butanol rectification column.

[0017] Further, the γ-butyrolactone production industrial waste liquid composition includes 35% to 45% of tetrahydrofuran, 15% to 30% of n-butanol, 30% to 35% of water, 0.9% to 1.1% of methanol and 0.7% to 0.75% of butanone by mass percentage.

[0018] Further, the pressure of the pre-separation column is 1.05 to 1.15 bar, the top temperature is 62 to 67℃, the bottom temperature is 92 to 98℃, the reflux ratio is 2.5 to 3.5, and the theoretical plate number is 23 to 27.

[0019] Further, the pressure of the n-butanol rectification column is 1.05 to 1.15 bar, the top temperature is 85 to 90℃, the bottom temperature is 115 to 120℃, the reflux ratio is 2.9 to 3.2, and the theoretical plate number is 12 to 16.

[0020] Further, the pressure of the water treatment column is 1.05 to 1.15 bar, the top temperature is 85 to 90℃, the bottom temperature is 96 to 103℃, the reflux ratio is 2.2 to 2.6, and the theoretical plate number is 6 to 9.

[0021] Further, the pressure of the butanone removal column is 1.1 to 1.3 bar, the top temperature is 65 to 70℃, the bottom temperature is 72 to 76℃, the reflux ratio is 5 to 6, and the theoretical plate number is 25 to 30.

[0022] Further, the pressure of the tetrahydrofuran extraction tower is 1.05-1.15 bar, the top temperature is 65-70 DEG C, the bottom temperature is 163-169 DEG C, the reflux ratio is 0.5-1, and the theoretical plate number is 50-55.

[0023] Further, the pressure of the solvent recovery tower is 1.05-1.15 bar, the top temperature is 80-85 DEG C, the bottom temperature is 193-197 DEG C, the reflux ratio is 1-2, and the theoretical plate number is 15-20.

[0024] Further, the feeding position of the pre-separation tower is the 8th-11th plate, the feeding position of the n-butanol refining tower is the 2nd-4th plate, the feeding position of the water treatment tower is the 2nd-4th plate, the feeding position of the butanone removal tower is the 8th-12th plate, the feeding position of the mixed solution containing tetrahydrofuran, water and methanol in the tetrahydrofuran extraction tower and the feeding position of the ion liquid recycling are the 40th-45th plate and the 2nd-6th plate respectively, and the feeding position of the solvent recovery tower is the 3rd-6th plate.

[0025] Further, the ion liquid is 1-butyl-3-methyl imidazole acetate.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] (1) The present application adopts extraction distillation to purify tetrahydrofuran and adopts heterogeneous azeotropic distillation to purify n-butanol. In the extraction distillation, ion liquid is used as an extractant to extract and separate the mixture of tetrahydrofuran, water and methanol, and in the heterogeneous azeotropic distillation, a phase separator is used to separate the mixed solution of n-butanol and water into an organic phase and an aqueous phase, and then the organic phase and the aqueous phase are respectively introduced into the n-butanol refining tower and the water treatment tower for separation and purification. The process is simple, no azeotrope is introduced in the heterogeneous azeotropic distillation section, and the process has the advantages of low energy consumption, green environmental protection and the like.

[0028] (2) The present application introduces the gamma-butyrolactone production industrial waste liquid into the pre-separation tower, the n-butanol refining tower, the water treatment tower, the butanone removal tower, the tetrahydrofuran extraction tower and the solvent recovery tower for 6-tower separation operation. The mass purity of the separated tetrahydrofuran can reach more than 99.95%, the recovery rate can reach more than 94.3%, the mass purity of the n-butanol can reach more than 99.5%, and the recovery rate can reach more than 99%. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a schematic diagram of the device of Example 1 of the present application.

[0030] In the figure: T1 - pre-separation column, T2 - n-butanol refining column, T3 - water treatment column, T4 - butanone removal column, T5 - tetrahydrofuran extraction column, T6 - solvent recovery column, E101 - preheater, E102, E103 - condenser, P1, P2, P3, P4 - centrifugal pump, M1 - mixer, D1 - phase separator. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application by combining the embodiments with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0032] Embodiment 1

[0033] A device for separating and purifying tetrahydrofuran and n-butanol from γ-butyrolactone production industrial waste liquid, comprising a pre-separation column T1, the pre-separation column T1 is provided with a feed inlet, the feed inlet is connected with a preheater E101, the pre-separation column T1 is connected to the feed inlet of a butanone removal column T4 through a centrifugal pump P1, the butanone removal column T4 is connected to the feed inlet of a tetrahydrofuran extraction column T5 through a centrifugal pump P2, the tetrahydrofuran extraction column T5 is connected to the feed inlet of a solvent recovery column T6 through a condenser E103, the solvent recovery column T6 is connected to the upper part of the tetrahydrofuran extraction column T5 through a condenser E103, and the tetrahydrofuran extraction column T5 is used to extract tetrahydrofuran product.

[0034] The pre-separation column T1 is connected to a mixer M1, and the mixture is condensed by a condenser E102 and then enters a phase separator D1, one outlet of the phase separator D1 is connected to the feed inlet of an n-butanol refining column T2 through a centrifugal pump P3, the other outlet of the phase separator D1 is connected to the feed inlet of a water treatment column T3 through a centrifugal pump P4, the outlet of the n-butanol refining column T2 and the outlet of the water treatment column T3 are both connected to the mixer M1, the mixture of the outlet of the n-butanol refining column T2, the outlet of the water treatment column T3 and the outlet of the pre-separation column T1 is mixed in the mixer M1, and the n-butanol product is extracted from the outlet of the n-butanol refining column T2.

[0035] Embodiment 2

[0036] The composition of the γ-butyrolactone production industrial waste liquid includes 43% tetrahydrofuran, 21% n-butanol, 33.7% water, 1% methanol, 0.73% butanone and 0.57% other impurities by mass percentage.

[0037] A method for separating and purifying tetrahydrofuran and n-butanol from γ-butyrolactone production industrial waste liquid by using the device of the above embodiment 1, comprising the following steps:

[0038] S1: The above-mentioned γ-butyrolactone production industrial waste liquid is introduced into the pre-separation column T1 for rectification from the 10th tray of the pre-separation column T1 at 25°C and 2 bar. The operating pressure of the pre-separation column T1 is 1.1 bar, the overhead temperature is 65.7°C, the bottom temperature is 95.8°C, the reflux ratio is 3, and the theoretical plate number is 25. A mixed solution containing tetrahydrofuran, water, methanol and butanone is obtained at the top of the pre-separation column T1, and a mixed solution containing n-butanol and water is obtained at the bottom of the pre-separation column T1;

[0039] S2: The mixed solution at the top of the pre-separation column T1 in step S1 is introduced into the butanone removal column T4 for rectification by a centrifugal pump P1 from the 10th tray of the butanone removal column T4. The operating pressure of the butanone removal column T4 is 1.2 bar, the overhead temperature is 67°C, the bottom temperature is 74.9°C, the reflux ratio is 5.5, and the theoretical plate number is 28. A mixed solution containing tetrahydrofuran, water and methanol is obtained at the top of the butanone removal column T4, and a butanone-containing waste liquid is obtained at the bottom of the butanone removal column T4;

[0040] S3: The mixed solution at the top of the butanone removal column T4 in step S2 is introduced into the tetrahydrofuran extraction column T5 by a centrifugal pump P2 from the 44th tray of the tetrahydrofuran extraction column T5. The tetrahydrofuran in the mixed solution is extracted using an ionic liquid 1-butyl-3-methylimidazolium acetate. The operating pressure of the tetrahydrofuran extraction column T5 is 1.1 bar, the overhead temperature is 68°C, the bottom temperature is 166°C, the reflux ratio is 0.7, and the theoretical plate number is 50. Tetrahydrofuran product is obtained at the top of the tetrahydrofuran extraction column T5, and a mixed solution containing ionic liquid, water and methanol is obtained at the bottom of the tetrahydrofuran extraction column T5. The mixed solution at the bottom of the tetrahydrofuran extraction column T5 is introduced into the solvent recovery column T6 from the 5th tray of the solvent recovery column T6. The operating pressure of the solvent recovery column T6 is 1.1 bar, the overhead temperature is 83°C, the bottom temperature is 195°C, the reflux ratio is 1.5, and the theoretical plate number is 16. A methanol-containing waste liquid is obtained at the top of the solvent recovery column T6, and ionic liquid is obtained at the bottom of the solvent recovery column T6. The ionic liquid is introduced into the tetrahydrofuran extraction column T5 from the 4th tray of the tetrahydrofuran extraction column T5 through a condenser E103. The ionic liquid can be recycled and reused;

[0041] S4: The mixed solution obtained from the bottom of the pre-separation column T1 is fed into the mixer M1, the condenser E102 and the phase separator D1. The phase separator D1 separates the mixed solution into an organic phase and an aqueous phase. The aqueous phase is fed into the water treatment column T3 by the centrifugal pump P4. The operating pressure of the water treatment column T3 is 1.1 bar, the top temperature is 88.6°C, the bottom temperature is 99.9°C, the reflux ratio is 2.4, and the theoretical plate number is 8. The wastewater is obtained from the bottom of the water treatment column T3. The organic phase is fed into the n-butanol refining column T2 by the centrifugal pump P3. The n-butanol refining column T2 is fed from the 3rd plate. The operating pressure of the n-butanol refining column T2 is 1.1 bar, the top temperature is 87.8°C, the bottom temperature is 118.6°C, the reflux ratio is 3.1, and the theoretical plate number is 14. The n-butanol product is obtained from the bottom of the n-butanol refining column T2.

[0042] After separation by the above method, the mass purity of tetrahydrofuran can reach 99.95%, and the recovery rate can reach 95.37%. The mass purity of n-butanol can reach 99.50%, and the recovery rate can reach 99.18%.

[0043] Example 3:

[0044] The composition of the γ-butyrolactone production industrial wastewater includes 40% tetrahydrofuran, 24% n-butanol, 33.7% water, 1% methanol, 0.73% butanone, and 0.57% other substances by mass percentage.

[0045] A method for separating and purifying tetrahydrofuran and n-butanol from γ-butyrolactone production industrial wastewater using the device of Example 1, comprising the following steps:

[0046] S1: The above-mentioned γ-butyrolactone production industrial wastewater is fed into the pre-separation column T1 from the 11th plate at 25°C and 2 bar. The operating pressure of the pre-separation column T1 is 1.1 bar, the top temperature is 65.8°C, the bottom temperature is 96°C, the reflux ratio is 3, and the theoretical plate number is 26. The mixed solution containing tetrahydrofuran, water, methanol, and butanone is obtained from the top of the pre-separation column T1, and the mixed solution containing n-butanol and water is obtained from the bottom of the pre-separation column T1.

[0047] S2: The mixed solution from the top of the pre-separation column T1 in step S1 is fed into the butanone removal column T4 by the centrifugal pump P1. The butanone removal column T4 is fed from the 10th plate. The operating pressure of the butanone removal column T4 is 1.2 bar, the top temperature is 67.9°C, the bottom temperature is 75.5°C, the reflux ratio is 5.5, and the theoretical plate number is 29. The mixed solution containing tetrahydrofuran, water, and methanol is obtained from the top of the butanone removal column T4, and the wastewater containing butanone is obtained from the bottom of the butanone removal column T4.

[0048] S3: The mixed solution from the top of the butanone column T4 in step S2 is pumped into the tetrahydrofuran extraction column T5 by the centrifugal pump P2, enters the column from the 44th tray of the tetrahydrofuran extraction column T5, and the tetrahydrofuran in the mixed solution is extracted by the ionic liquid 1-butyl-3-methylimidazolium acetate, the operating pressure of the tetrahydrofuran extraction column T5 is 1.1 bar, the column top temperature is 71.3°C, the column bottom temperature is 168.8°C, the reflux ratio is 0.7, the number of theoretical plates is 52, and the tetrahydrofuran product is obtained from the top of the tetrahydrofuran extraction column T5, and the mixed solution containing ionic liquid, water and methanol is obtained from the column bottom; the mixed solution from the column bottom of the tetrahydrofuran extraction column T5 is pumped into the solvent recovery column T6 from the 5th tray of the solvent recovery column T6, the operating pressure of the solvent recovery column T6 is 1.1 bar, the column top temperature is 76°C, the column bottom temperature is 192°C, the reflux ratio is 1.5, the number of theoretical plates is 18, the waste liquid containing methanol is obtained from the top of the solvent recovery column T6, and the ionic liquid is obtained from the column bottom, which is recycled and reused by entering the tetrahydrofuran extraction column T5 from the 4th tray of the tetrahydrofuran extraction column T5 through the condenser E103;

[0049] S4: The mixed solution obtained from the column bottom of the pre-separation column T1 in step 1 is pumped into the phase separator D1 through the mixer M1 and the condenser E102, the mixed solution is separated into an organic phase and an aqueous phase by the phase separator D1, the aqueous phase is pumped into the water treatment column T3 from the 3rd tray of the water treatment column T3, the operating pressure of the water treatment column T3 is 1.1 bar, the column top temperature is 88.8°C, the column bottom temperature is 100.2°C, the reflux ratio is 2.4, the number of theoretical plates is 8, and the waste water is obtained from the column bottom of the treatment column T3; the organic phase is pumped into the n-butanol refining column T2 from the 3rd tray of the n-butanol refining column T2, the operating pressure of the n-butanol refining column T2 is 1.1 bar, the column top temperature is 87.9°C, the column bottom temperature is 118.7°C, the reflux ratio is 3.2, the number of theoretical plates is 14, and the n-butanol product is obtained from the column bottom of the n-butanol refining column T2.

[0050] After separation by the above method: the mass purity of tetrahydrofuran can reach 99.98%, the recovery rate can reach 95.06%, and the mass purity of n-butanol can reach 99.54%, the recovery rate can reach 99.27%.

[0051] Example 4:

[0052] The composition of the γ-butyrolactone production industrial waste liquid includes, by mass percentage: 35% tetrahydrofuran, 29% n-butanol, 33.7% water, 1% methanol, 0.73% butanone, and 0.57% other substances.

[0053] A method for separating and purifying tetrahydrofuran and n-butanol from a γ-butyrolactone production industrial waste liquid by using the device of the above example 1, comprising the following steps:

[0054] S1: The above-mentioned γ-butyrolactone production industrial waste liquid is introduced into the pre-separation column T1 from the 10th tray of the pre-separation column T1 at 25°C and 2 bar, the operating pressure of the pre-separation column T1 is 1.1 bar, the overhead temperature is 65.8°C, the bottom temperature is 96.2°C, the reflux ratio is 3.1, the theoretical plate number is 24, the mixed solution containing tetrahydrofuran, water, methanol and butanone is obtained at the top of the pre-separation column T1, and the mixed solution containing n-butanol and water is obtained at the bottom of the pre-separation column T1;

[0055] S2: The mixed solution at the top of the pre-separation column T1 in step S1 is introduced into the butanone removal column T4 through the centrifugal pump P1, and is introduced from the 10th tray of the butanone removal column T4, the operating pressure of the butanone removal column T4 is 1.2 bar, the overhead temperature is 67.9°C, the bottom temperature is 76.5°C, the reflux ratio is 5.5, the theoretical plate number is 28, the mixed solution containing tetrahydrofuran, water and methanol is obtained at the top of the butanone removal column T4, and the waste liquid containing butanone is obtained at the bottom of the butanone removal column T4;

[0056] S3: The mixed solution at the top of the butanone removal column T4 in step S2 is introduced into the tetrahydrofuran extraction column T5 through the centrifugal pump P2, and is introduced from the 44th tray of the tetrahydrofuran extraction column T5, the ion liquid 1-butyl-3-methyl imidazole acetate is used to extract the tetrahydrofuran in the mixed solution, the operating pressure of the tetrahydrofuran extraction column T5 is 1.1 bar, the overhead temperature is 71.3°C, the bottom temperature is 167.3°C, the reflux ratio is 0.7, the theoretical plate number is 54, the tetrahydrofuran product is obtained at the top of the tetrahydrofuran extraction column T5, and the mixed solution containing ion liquid, water and methanol is obtained at the bottom of the tetrahydrofuran extraction column T5; the mixed solution at the bottom of the tetrahydrofuran extraction column T5 is introduced into the solvent recovery column T6 from the 5th tray of the solvent recovery column T6, the operating pressure of the solvent recovery column T6 is 1.1 bar, the overhead temperature is 72.3°C, the bottom temperature is 192.4°C, the reflux ratio is 2, the theoretical plate number is 17, the waste liquid containing methanol is obtained at the top of the solvent recovery column T6, and the ion liquid is obtained at the bottom of the solvent recovery column T6, which is introduced into the tetrahydrofuran extraction column T5 through the condenser E103 from the 4th tray of the tetrahydrofuran extraction column T5, and can be recycled and reused;

[0057] S4: the mixed solution obtained from the bottom of the pre-separation column T1 is introduced into the phase separator D1 through the mixer M1 and the condenser E102, the phase separator D1 separates the mixed solution into an organic phase and an aqueous phase, the aqueous phase is introduced into the water treatment column T3 through the centrifugal pump P4, the water treatment column T3 is operated at a pressure of 1.1 bar, a top temperature of 88.8°C, a bottom temperature of 100.5°C, a reflux ratio of 2.4, and a theoretical plate number of 8, and the wastewater is obtained from the bottom of the water treatment column T3; the organic phase is introduced into the n-butanol refining column T2 through the centrifugal pump P3, the n-butanol refining column T2 is operated at a pressure of 1.1 bar, a top temperature of 88.1°C, a bottom temperature of 118.7°C, a reflux ratio of 3.1, and a theoretical plate number of 14, and the n-butanol product is obtained from the bottom of the n-butanol refining column T2.

[0058] After separation by the above method, the mass purity of the tetrahydrofuran can reach 99.97%, and the recovery rate can reach 94.3%, and the mass purity of the n-butanol can reach 99.56%, and the recovery rate can reach 99.25%.

[0059] The above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the protection scope of the present application. Based on the idea of the present application, those skilled in the art can modify or equivalently replace the technical solutions of the present application without departing from the essence and scope of the present application.

Claims

1. An apparatus for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production, characterized in that, The system includes a pre-separation tower with a feed inlet. The top outlet of the pre-separation tower is connected to the feed inlet of a methyl ethyl ketone (MEK) removal tower. The top outlet of the MEK removal tower is connected to the feed inlet of a tetrahydrofuran (THF) extraction tower. The bottom outlet of the THF extraction tower is connected to the feed inlet of a solvent recovery tower. The bottom outlet of the solvent recovery tower is connected to the feed inlet at the top of the THF extraction tower. The top outlet of the THF extraction tower produces tetrahydrofuran product. The bottom outlet of the pre-separation tower is connected to a mixer. The mixer is connected to a phase separator. One outlet of the phase separator is connected to the feed inlet of a n-butanol refining tower. The other outlet of the phase separator is connected to the feed inlet of a water treatment tower. The top outlets of both the n-butanol refining tower and the water treatment tower are connected to the mixer. The bottom outlet of the n-butanol refining tower produces n-butanol product.

2. The apparatus for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 1, characterized in that, The pipe connected to the feed inlet of the pre-separation tower is equipped with a preheater, the pipe connected to the mixer and the phase separator is equipped with a condenser, and the pipe connected to the bottom outlet of the solvent recovery tower and the feed inlet at the top of the tetrahydrofuran extraction tower is equipped with a condenser.

3. The apparatus for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 1, characterized in that, A centrifugal pump is installed in the pipeline connecting the top outlet of the pre-separation tower to the inlet of the butanone removal tower; a centrifugal pump is installed in the pipeline connecting the top outlet of the butanone removal tower to the inlet of the tetrahydrofuran extraction tower; a centrifugal pump is installed in the pipeline connecting the phase separator to the inlet of the n-butanol purification tower; and a centrifugal pump is installed in the pipeline connecting the phase separator to the inlet of the water treatment tower.

4. A method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production using the apparatus described in any one of claims 1-3, characterized in that, Includes the following steps: S1: The industrial waste liquid from the production of γ-butyrolactone is preheated and then fed into a pre-separation tower for distillation. A mixed solution containing tetrahydrofuran, water, methanol and butanone is obtained at the top of the tower, and a mixed solution containing n-butanol and water is obtained at the bottom of the tower. S2: The mixed solution at the top of the pre-separation tower in step S1 is passed into the butanone removal tower for distillation. A mixed solution containing tetrahydrofuran, water and methanol is obtained at the top of the tower, and butanone waste liquid is obtained at the bottom of the tower. S3: The mixed solution from the top of the methyl ethyl ketone (MEK) removal tower in step S2 is passed into a tetrahydrofuran extraction tower. Ionic liquid is used to extract tetrahydrofuran from the mixed solution. Tetrahydrofuran product is obtained at the top of the tower, and a mixed solution containing ionic liquid, water, and methanol is obtained at the bottom of the tower. The mixed solution from the bottom of the tetrahydrofuran extraction tower is passed into a solvent recovery tower. Methanol waste liquid is obtained at the top of the solvent recovery tower, and ionic liquid is obtained at the bottom of the tower. The ionic liquid is recycled back into the tetrahydrofuran extraction tower. S4: The mixed solution obtained from the bottom of the pre-separation tower in step 1 is fed into a phase separator. The phase separator separates the mixed solution into an organic phase and an aqueous phase. The aqueous phase is fed into a water treatment tower, and the organic phase is fed into a n-butanol purification tower. The n-butanol product is obtained from the bottom of the n-butanol purification tower.

5. The method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 4, characterized in that, The industrial waste liquid from the production of γ-butyrolactone, by mass percentage, comprises 35%–45% tetrahydrofuran, 15%–30% n-butanol, 30%–35% water, 0.9%–1.1% methanol, and 0.7%–0.75% methyl ethyl ketone.

6. The method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 4, characterized in that, The pre-separation tower has a pressure of 1.05–1.15 bar, a top temperature of 62–67°C, a bottom temperature of 92–98°C, a reflux ratio of 2.5–3.5, and a theoretical plate number of 23–27.

7. The method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 4, characterized in that, The pressure of the n-butanol refining column is 1.05–1.15 bar, the top temperature is 85–90 °C, the bottom temperature is 115–120 °C, the reflux ratio is 2.9–3.2, and the theoretical plate number is 12–16.

8. The method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 4, characterized in that, The water treatment tower has a pressure of 1.05–1.15 bar, a top temperature of 85–90°C, a bottom temperature of 96–103°C, a reflux ratio of 2.2–2.6, and a theoretical plate number of 6–9.

9. The method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 4, characterized in that, The pressure of the methyl ethyl ketone (MEK) removal column is 1.1–1.3 bar, the top temperature is 65–70°C, the bottom temperature is 72–76°C, the reflux ratio is 5–6, and the theoretical plate number is 25–30.

10. The method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 4, characterized in that, The pressure of the tetrahydrofuran extraction column is 1.05–1.15 bar, the top temperature is 65–70 °C, the bottom temperature is 163–169 °C, the reflux ratio is 0.5–1, and the theoretical plate number is 50–55.

11. The method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 4, characterized in that, The solvent recovery tower has a pressure of 1.05–1.15 bar, a top temperature of 80–85°C, a bottom temperature of 193–197°C, a reflux ratio of 1–2, and a theoretical plate number of 15–20.

12. The method for separating and purifying tetrahydrofuran and n-butanol from industrial wastewater from γ-butyrolactone production according to claim 4, characterized in that, The feed positions for the pre-separation tower are trays 8 to 11; the feed positions for the n-butanol purification tower are trays 2 to 4; the feed positions for the water treatment tower are trays 2 to 4; the feed positions for the butanone removal tower are trays 8 to 12; the feed positions for the tetrahydrofuran extraction tower containing a mixed solution of tetrahydrofuran, water, and methanol are trays 40 to 45 and trays 2 to 6 for ionic liquid recycling, respectively; and the feed positions for the solvent recovery tower are trays 3 to 6.

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