Recovery system and method for phenol and acetone in bisphenol A production device

Abstract

The invention belongs to the field of separation of multiple systems of phenol, acetone and water, and particularly relates to a system and a method for recovering phenol and acetone in a bisphenol A production device. The system comprises a buffer tank, a liquid delivery pump, a pervaporation membrane device and a normal-pressure rectifying tower which are sequentially communicated, the pervaporation membrane device comprises a retentate side and a permeation side, and the retentate side is communicated with the normal-pressure rectifying tower. According to the technical scheme provided by the invention, based on pervaporation and rectification coupling, the azeotropic point problem of phenol and water is solved, high-concentration phenol can be recovered, an entrainer does not need to be introduced, separation units are reduced, and pollution of components outside the device is avoided.

Description

Technical Field

[0001] This invention belongs to the field of separation of phenol, acetone and water multi-component systems, and specifically relates to a phenol and acetone recovery system and method in a bisphenol A production unit. Background Technology

[0002] In bisphenol A production, the condensation reaction produces water, excess phenol, and acetone, forming a phenol-water-acetone mixture. Since the bisphenol A production process uses large quantities of phenol and acetone, to reduce raw material consumption in bisphenol A production units, it is usually considered to recover excess phenol and unreacted acetone for recycling.

[0003] US Patent 9255053B2 discloses a method for treating residual streams from the production of bisphenol-A, which hydrolyzes a portion of the residual streams in the process into acetone and phenol, generating an effluent stream. First, acetone is recovered by distillation. Then, the phenol-containing mixed-phase stream is treated with a water-immiscible organic solvent (cumene, toluene, etc.) to extract phenol and unhydrolyzed heavy organic compounds into the solvent, producing an organic phase containing the solvent, phenol, and unhydrolyzed heavy aromatic compounds, and a remaining aqueous phase. At least a portion of the phenol and organic solvent are then recovered from the organic phase.

[0004] Patent CN 114315503A discloses an optimized method for a reaction system for preparing bisphenol A, which includes a solvent recovery unit comprising a dehydration tower, an acetone recovery tower, and a phenol tower in the bisphenol A production process. The phenol recovery system includes a dehydration tower and a phenol refining tower; at least a portion of the light and low-boiling-point components are condensed and fed into the dehydration tower; the gas phase at the top of the tower enters the acetone recovery tower to obtain recovered acetone, and the bottom product is separated into oil and water to obtain an azeotropic agent mainly composed of ethylbenzene, which is recycled back to the dehydration tower; the liquid phase at the bottom of the dehydration tower enters the phenol refining tower, the purified phenol is collected from the gas phase at the top of the tower, and the byproduct mixed polyphenols are discharged from the bottom of the tower.

[0005] The solvent recovery unit disclosed in patent CN 117384015A, a production process and apparatus for synthesizing bisphenol A by resin method, also uses ethylbenzene as an azeotropic agent to separate phenol by azeotropic distillation, and further separates acetone and water by distillation in an acetone recovery tower.

[0006] CN110028381A discloses a method for separating ethanol, propanol and butanol from ABE fermentation pervaporation liquid by distillation, which involves separating high concentrations of ethanol, butanol and acetone from acetone-butanol fermentation mash.

[0007] In general, current methods for recovering phenol and acetone in bisphenol A production plants mostly employ distillation. Since phenol and water form an azeotrope during the recovery process, ordinary distillation cannot break the thermodynamic equilibrium to obtain high-purity phenol. Therefore, azeotropic distillation is often used to introduce additional azeotropic components from outside the system, and a separation unit is also required to separate the azeotropic agent from acetone and water.

[0008] Pervaporation is a novel membrane-based separation technology, particularly suitable for separating near-boiling and azeotropic organic mixtures that are difficult or impossible to separate by distillation. It utilizes the vapor pressure difference between components in a liquid mixture as the driving force, and achieves separation by leveraging the differences in dissolution and diffusion rates of the components within the membrane. Its outstanding advantage is its ability to efficiently and with low energy consumption accomplish separation tasks that are difficult to achieve using traditional methods such as distillation, extraction, and absorption. Based on the above background, and addressing the problems existing in current bisphenol A production units that only use distillation to recover phenol and acetone, pervaporation is suitable for separating azeotropic systems containing phenol and water. Therefore, a pervaporation membrane system is used to separate the inorganic component water and the organic components (phenol and acetone) in the solvent recovery unit. However, due to the high content of phenol and acetone in the mixture, it is difficult to further separate phenol and acetone using only pervaporation. Therefore, a method coupling pervaporation and distillation is proposed to recover phenol and acetone, overcoming the azeotropic composition of phenol and water, and eliminating the need to introduce an additional azeotropic agent into the unit, thus reducing the number of azeotropic agent separation units. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a system and method for recovering phenol and acetone in a bisphenol A production unit. The technical solution provided by this invention is based on the coupling of pervaporation and distillation, solving the azeotropic problem of phenol and water. It can recover high-concentration phenol without introducing an azeotropic agent, reducing the number of separation units and avoiding contamination from external components. This invention thus solves the problems of conventional distillation methods failing to break through the azeotropic composition when phenol and water form an azeotrope, resulting in low phenol concentrations, and the issue that while azeotropic distillation can recover high-concentration phenol, it introduces an external component—the azeotropic agent—and requires an additional azeotropic agent separation unit.

[0010] The technical solution provided by this invention is as follows: A phenol and acetone recovery system in a bisphenol A production unit includes a buffer tank, a liquid transfer pump, a pervaporation membrane device, and an atmospheric distillation column arranged in sequence. The pervaporation membrane device includes a permeate side (i.e., the side that has not been permeated) and a permeate side separated by the pervaporation membrane. The permeate side is connected to the atmospheric distillation column.

[0011] Based on the above technical solution: The mixture of phenol, acetone, and water from the reaction section first enters the buffer tank and is then transported to the pervaporation membrane unit via a liquid transfer pump. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone and water, water preferentially permeates through the membrane and thus accumulates on the permeate side of the membrane module, while the organic phase accumulates on the effluent side of the membrane module. Water from the permeate side can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column for further separation and purification. The acetone obtained at the top of the atmospheric distillation column is recycled to the acetone refining column in the raw material refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the raw material refining section for recycling.

[0012] Specifically: The buffer tank is also connected to the bisphenol A reaction section; The top of the atmospheric distillation column is connected to an acetone recovery pipeline; The bottom of the atmospheric distillation column is connected to a phenol recovery pipeline.

[0013] Specifically: The pervaporation membrane device includes a plurality of pervaporation membrane units, and each of the pervaporation membrane units is connected in series or in parallel. The permeation side of each of the aforementioned pervaporation membrane units is connected to the main vacuum pump pipe.

[0014] Specifically: the pervaporation membrane of the pervaporation membrane device is selected from any one of molecular sieve membrane, carboxymethyl cellulose membrane, polyethyleneimine-tannic acid composite membrane, amorphous silica membrane, nanofiber composite polyacrylonitrile membrane or modified PVA membrane; the pervaporation membrane is a flat sheet membrane, tubular membrane or hollow fiber membrane.

[0015] The present invention also provides a method for recovering phenol and acetone in a bisphenol A production unit, comprising the following steps: using the recovery system described above for recovery, passing a mixture of phenol, acetone and water generated in the raw material refining and reaction stages of the bisphenol A production process into the buffer tank, recovering acetone through the top of the atmospheric distillation column, and recovering phenol through the bottom of the atmospheric distillation column.

[0016] Based on the above technical solution, the mixture of phenol, acetone, and water from the raw material refining and reaction section, with a mass composition of 70%-90% phenol, 5-15% water, and 2-15% acetone, is pressurized by a pump and enters the membrane system of the pervaporation unit. A vacuum is drawn on the permeate side of the membrane module, and the water that preferentially permeates through the membrane is enriched on the permeate side. Organic components such as phenol and acetone are retained on the effluent side. The side with high concentration of water is transported to the water treatment unit, while the side with mixed organic solvents containing high concentrations of phenol and acetone is transported to the atmospheric distillation column for the separation of phenol and acetone. The recovered acetone and phenol are recycled to the respective raw material refining towers for reuse.

[0017] Specifically, in the mixture of phenol, acetone, and water: The weight percentage of phenol is 70-90%; The weight percentage of acetone is 2-15%.

[0018] Specifically: In the pervaporation membrane device, the absolute pressure on the permeate side of each pervaporation membrane unit is 2000~5000 Pa.

[0019] Specifically: In the pervaporation membrane device, the operating temperature of each pervaporation membrane is between 70 and 130°C.

[0020] Specifically: In the atmospheric distillation column, the top temperature is 55~70℃, the bottom temperature is 180~190℃, and the reflux ratio is 2~5.

[0021] Specifically, the recovered acetone content is greater than or equal to 99 wt%.

[0022] Specifically, the recovered phenol content is greater than or equal to 98.5 wt%.

[0023] The beneficial effects of this invention are as follows: The present invention eliminates the need to introduce external components such as azeotropic agents into the azeotropic distillation process, reducing the use of toxic and harmful solvents and eliminating the need for additional azeotropic agent separation units. Simultaneously, it overcomes the limitations of conventional distillation methods on azeotropic composition. For the recovery of phenol and acetone in bisphenol A units, a separation method coupling pervaporation and distillation can achieve a recovery rate of over 98%. Attached Figure Description

[0024] Figure 1 This is a system diagram of the phenol and acetone recovery system in the bisphenol A production apparatus provided by the present invention.

[0025] Figure 2 This is a structural diagram of the phenol and acetone recovery system in the bisphenol A production apparatus provided by the present invention.

[0026] Appendix Figure 1 , 2 The structures represented by each label are listed below: 1. Buffer tank; 2. Buffer tank; 3. Pervaporation membrane device; 4. Atmospheric distillation column. Detailed Implementation

[0027] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0028] Unless otherwise specified, the test methods used in the embodiments are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Molecular sieve membranes, carboxymethyl cellulose membranes, polyethyleneimine-tannic acid composite membranes, amorphous silica membranes, nanofiber composite polyacrylonitrile membranes, or modified PVA membranes can all be purchased separately or obtained according to the implementation methods in the examples.

[0032] In one specific implementation, such as Figure 1 , 2 As shown, the phenol and acetone recovery system in the bisphenol A production unit includes a buffer tank 1, a liquid transfer pump 2, a pervaporation membrane device 3, and an atmospheric distillation column 4, which are connected in sequence. The pervaporation membrane device 3 includes a permeate side and a permeate side, with the permeate side connected to the atmospheric distillation column 4. The buffer tank 1 is also connected to the bisphenol A reaction section. The top of the atmospheric distillation column 4 is connected to an acetone recovery pipeline. The bottom of the atmospheric distillation column 4 is connected to a phenol recovery pipeline.

[0033] The mixture of phenol, acetone, and water from the reaction section first enters the buffer tank 1 and is then transported to the pervaporation membrane unit 3 via the liquid transfer pump 2. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone and water, water preferentially permeates through the membrane and thus accumulates on the permeate side of the membrane module, while the organic phase accumulates on the effluent side of the membrane module.

[0034] Water from the permeate side can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column 4 for further separation and purification. The acetone obtained at the top of the atmospheric distillation column 4 is recycled to the acetone refining column in the raw material refining section. The phenol obtained at the bottom of the column is transported to the phenol refining column in the raw material refining section for recycling.

[0035] In another specific embodiment, the phenol and acetone recovery system in the bisphenol A production unit includes a buffer tank 1, a liquid transfer pump 2, a pervaporation membrane device 3, and an atmospheric distillation column 4, which are connected in sequence. The pervaporation membrane device 3 includes a permeate side and a permeate side, with the permeate side connected to the atmospheric distillation column 4. The buffer tank 1 is also connected to the bisphenol A reaction section. The top of the atmospheric distillation column 4 is connected to an acetone recovery pipeline. The bottom of the atmospheric distillation column 4 is connected to a phenol recovery pipeline. Furthermore, the pervaporation membrane device 3 includes several pervaporation membrane units, which are connected in series or parallel. The permeate side of each pervaporation membrane unit is connected to a vacuum pump mains.

[0036] The mixture of phenol, acetone, and water from the reaction section first enters the buffer tank 1 and is then transported to the pervaporation membrane unit 3 via the liquid transfer pump 2. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone and water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each parallel or series membrane module, while the organic phase accumulates on the effluent side of each parallel or series membrane module.

[0037] Water from the permeate side of each parallel or series membrane module can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column 4 for further separation and purification. The acetone obtained at the top of the atmospheric distillation column 4 is recycled to the acetone refining column in the feed refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the feed refining section for recycling.

[0038] The production capacity and efficiency of a pervaporation membrane system can be adjusted by adding or removing membrane units and by varying the number of series-connected membrane units. Alternatively, the desired effect can be achieved by changing the membrane material.

[0039] In another specific embodiment, the phenol and acetone recovery system in the bisphenol A production unit includes a buffer tank 1, a liquid transfer pump 2, a pervaporation membrane device 3, and an atmospheric distillation column 4, which are connected in sequence. The pervaporation membrane device 3 includes a permeate side and a permeate side, with the permeate side connected to the atmospheric distillation column 4. The buffer tank 1 is also connected to the bisphenol A reaction section. The top of the atmospheric distillation column 4 is connected to an acetone recovery pipeline. The bottom of the atmospheric distillation column 4 is connected to a phenol recovery pipeline. Further, the pervaporation membrane device 3 includes three pervaporation membrane units, which are connected in series. The permeate side of each pervaporation membrane unit is connected to a vacuum pump mains.

[0040] The mixture of phenol, acetone, and water from the reaction section first enters the buffer tank 1 and is then transported to the pervaporation membrane unit 3 via the liquid transfer pump 2. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone and water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each series-connected membrane module, while the organic phase accumulates on the effluent side of each series-connected membrane module.

[0041] Water from the permeate side of each membrane module connected in series can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column 4 for further separation and purification. The acetone obtained at the top of the atmospheric distillation column 4 is recycled to the acetone refining column in the feed refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the feed refining section for recycling.

[0042] The production capacity and efficiency of the pervaporation membrane system can be adjusted by using three stages connected in series.

[0043] In another specific embodiment, the phenol and acetone recovery system in the bisphenol A production unit includes a buffer tank 1, a liquid transfer pump 2, a pervaporation membrane device 3, and an atmospheric distillation column 4, which are sequentially connected. The pervaporation membrane device 3 includes a permeate side and a permeate side, with the permeate side connected to the atmospheric distillation column 4. The buffer tank 1 is also connected to the bisphenol A reaction section. The top of the atmospheric distillation column 4 is connected to an acetone recovery pipeline. The bottom of the atmospheric distillation column 4 is connected to a phenol recovery pipeline. Further, the pervaporation membrane device 3 includes three pervaporation membrane units connected in parallel. The permeate side of each pervaporation membrane unit is connected to a vacuum pump mains.

[0044] The mixture of phenol, acetone, and water from the reaction section first enters the buffer tank 1 and is then transported to the pervaporation membrane unit 3 via the liquid transfer pump 2. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone and water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each parallel membrane module, while the organic phase accumulates on the effluent side of each parallel membrane module.

[0045] Water from the permeate side of each parallel membrane module can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column 4 for further separation and purification. The acetone obtained at the top of the atmospheric distillation column 4 is recycled to the acetone refining column in the feed refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the feed refining section for recycling.

[0046] The production capacity and efficiency of the pervaporation membrane system can be adjusted by connecting three stages in parallel.

[0047] Example 1 In the bisphenol A production process, the raw material refining and reaction section receives a mixture of 78% phenol, 12% water, and 10% acetone at a temperature of 90°C. This mixture first enters buffer tank 1 and is then pumped by liquid transfer pump 2 to the pervaporation membrane unit 3. The membrane module uses an amorphous silica membrane (Pervatech BV, Netherlands). The membrane module operating temperature is maintained at 90°C, and the absolute pressure on the permeate side is controlled at 2500 Pa. After 2 hours of operation, the water content of the permeate reaches 99.6%, and the water content on the residual side decreases to 2%. The residual side feed enters an atmospheric distillation column 4 for separation. The column top temperature is 62°C, the bottom temperature is 185°C, the operating reflux ratio is 3.0, the purity of acetone at the top is 99.3% with a recovery rate of 98.7%, and the purity of phenol at the bottom is 98.8% with a recovery rate of 98.5%.

[0048] The mixture from the reaction section, consisting of 78% phenol, 12% water, and 10% acetone, first enters a buffer tank and is then transported to the pervaporation membrane unit via a liquid transfer pump. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone versus water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each series-connected membrane module, while the organic phase accumulates on the effluent side of each series-connected membrane module.

[0049] Water from the pervaporation membrane unit on the permeate side can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column for further separation and purification. The acetone obtained at the top of the atmospheric distillation column is recycled to the acetone refining column in the raw material refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the raw material refining section for circulation.

[0050] Example 2 In the bisphenol A production process, a mixture of phenol, acetone, and water flowing out from the raw material refining and reaction stages has a composition of 85% phenol, 7% water, and 8% acetone, at a temperature of 94°C. This mixture is pumped by transfer pump 2 to a pervaporation membrane system 3, where a vacuum of 4000 Pa is maintained on the permeate side of the modified PVA membrane using a vacuum pump. The water content in the permeate reaches 99.7%, while the water content in the residual liquid decreases to 1%, and the phenol content increases to 88%. The residual liquid is directly fed into an atmospheric distillation column 4, with a top temperature of 58°C, a bottom temperature of 188°C, an operating reflux ratio of 5.0, an acetone purity of 99.5% and a recovery rate of 98.9% at the top, and a phenol purity of 99.0% and a recovery rate of 98.8% at the bottom.

[0051] The mixture from the reaction section, consisting of 85% phenol, 7% water, and 8% acetone, first enters a buffer tank and is then transported to the pervaporation membrane unit via a liquid transfer pump. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone versus water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each series-connected membrane module, while the organic phase accumulates on the effluent side of each series-connected membrane module.

[0052] Water from the pervaporation membrane unit on the permeate side can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column for further separation and purification. The acetone obtained at the top of the atmospheric distillation column is recycled to the acetone refining column in the raw material refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the raw material refining section for circulation.

[0053] Example 3 A mixture of 82% phenol, 12% water, and 6% acetone was heated to 95°C and fed into a NaA-type molecular sieve membrane (Jiangsu Jiutian High-Tech Co., Ltd.) module system. The membrane system was arranged in a three-stage series configuration, maintaining a vacuum of 3000 Pa. The water concentration on the permeate side was 99.5%, the water concentration on the residual side was <1%, and the phenol concentration was 93%. The residual liquid was directly fed into atmospheric distillation column 4. The top temperature of the column was stably controlled at 57°C to produce acetone with a purity of 99.6%, and the bottom temperature was 183°C to produce phenol with a purity of 99.82%. The phenol recovery rate reached 98.7%, and the acetone recovery rate was 99.3%.

[0054] The mixture from the reaction section, consisting of 82% phenol, 12% water, and 6% acetone, first enters a buffer tank and is then transported to the pervaporation membrane unit via a liquid transfer pump. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone versus water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each series-connected membrane module, while the organic phase accumulates on the effluent side of each series-connected membrane module.

[0055] Water from the pervaporation membrane unit on the permeate side can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column for further separation and purification. The acetone obtained at the top of the atmospheric distillation column is recycled to the acetone refining column in the raw material refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the raw material refining section for circulation.

[0056] Example 4 Referring to Example 1, the difference is that a carboxymethyl cellulose membrane is used. The carboxymethyl cellulose membrane powder is dissolved in deionized water and cast into a film under normal conditions.

[0057] A mixture of 80% phenol, 11% water, and 9% acetone, at a temperature of 90°C, first enters buffer tank 1 and then is pumped to pervaporation membrane unit 3 using liquid transfer pump 2. The membrane module uses a carboxymethyl cellulose membrane, and the operating temperature is maintained at 90°C, with the absolute pressure on the permeate side controlled at 3000 Pa. After 2 hours of operation, the water content of the permeate reaches 99.5%, and the water content on the residual side decreases to 1.5%. The residual side feed enters atmospheric distillation column 4 for separation. The column top temperature is 62°C, the bottom temperature is 184°C, the operating reflux ratio is 3.5, the purity of acetone at the top is 99.4% with a recovery rate of 98.5%, and the purity of phenol at the bottom is 98.9% with a recovery rate of 98.7%.

[0058] The mixture from the reaction section, consisting of 80% phenol, 11% water, and 9% acetone, first enters a buffer tank and is then transported to the pervaporation membrane unit via a liquid transfer pump. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone versus water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each series-connected membrane module, while the organic phase accumulates on the effluent side of each series-connected membrane module.

[0059] Water from the pervaporation membrane unit on the permeate side can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column for further separation and purification. The acetone obtained at the top of the atmospheric distillation column is recycled to the acetone refining column in the raw material refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the raw material refining section for circulation.

[0060] Example 5 Referring to Example 1, the difference is that a polyethyleneimine-tannic acid composite membrane is used. Polyethyleneimine and tannic acid are mixed in weakly acidic water and immersed in the substrate. After soaking for a period of time, the membrane is removed, rinsed with water, and dried to obtain the polyethyleneimine-tannic acid composite membrane.

[0061] In the bisphenol A production process, the raw material refining and reaction section receives a mixture of 78% phenol, 12% water, and 10% acetone at a temperature of 90°C. This mixture first enters buffer tank 1 and is then pumped by liquid transfer pump 2 to the pervaporation membrane unit 3. The membrane module uses a polyethyleneimine-tannic acid composite membrane, and the operating temperature is maintained at 90°C, with the absolute pressure on the permeate side controlled at 3500 Pa. After two hours of operation, the water content of the permeate reaches 99.8%, while the water content on the residual side decreases to 0.8%. The residual side feed enters an atmospheric distillation column 4 for separation. The column top temperature is 59°C, the bottom temperature is 186°C, the operating reflux ratio is 4.0, the purity of the acetone at the top is 99.5% with a recovery rate of 99.0%, and the purity of the phenol at the bottom is 99.1% with a recovery rate of 98.9%.

[0062] The mixture from the reaction section, consisting of 78% phenol, 12% water, and 10% acetone, first enters a buffer tank and is then transported to the pervaporation membrane unit via a liquid transfer pump. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone versus water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each series-connected membrane module, while the organic phase accumulates on the effluent side of each series-connected membrane module.

[0063] Water from the pervaporation membrane unit on the permeate side can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column for further separation and purification. The acetone obtained at the top of the atmospheric distillation column is recycled to the acetone refining column in the raw material refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the raw material refining section for circulation.

[0064] Example 6 Referring to Example 1, the difference lies in the use of a nanofiber composite polyacrylonitrile membrane. The nanofiber composite polyacrylonitrile membrane is prepared by dissolving polyacrylonitrile in N,N-dimethylformamide solvent and then electrospinning under normal conditions.

[0065] In the bisphenol A production process, the raw material refining and reaction section receives a mixture of 78% phenol, 15% water, and 7% acetone at a temperature of 88°C. This mixture first enters buffer tank 1 and is then pumped by liquid transfer pump 2 to the pervaporation membrane unit 3. The membrane module uses a nanofiber composite polyacrylonitrile membrane, and the operating temperature is maintained at 90°C, with the absolute pressure on the permeate side controlled at 2800 Pa. After 1.5 hours of operation, the water content of the permeate reaches 99.4%, and the water content on the residual side decreases to 1.2%. The residual side feed enters an atmospheric distillation column 4 for separation. The column top temperature is 60°C, the bottom temperature is 182°C, the operating reflux ratio is 3.5, the purity of acetone at the top is 98.8% with a recovery rate of 99.1%, and the purity of phenol at the bottom is 99.0% with a recovery rate of 98.8%.

[0066] The mixture from the reaction section, consisting of 78% phenol, 15% water, and 7% acetone, first enters a buffer tank and is then transported to the pervaporation membrane unit via a liquid transfer pump. A vacuum is drawn on the permeate side of the membrane module. Due to the difference in selective permeability of the membrane material to organic components such as phenol and acetone versus water, water preferentially permeates through the membrane and thus accumulates on the permeate side of each series-connected membrane module, while the organic phase accumulates on the effluent side of each series-connected membrane module.

[0067] Water from the pervaporation membrane unit on the permeate side can be transported to a water treatment unit. A mixed organic solvent containing high concentrations of phenol and acetone is transported from the permeate side to an atmospheric distillation column for further separation and purification. The acetone obtained at the top of the atmospheric distillation column is recycled to the acetone refining column in the raw material refining section, and the phenol obtained at the bottom of the column is transported to the phenol refining column in the raw material refining section for circulation.

[0068] This invention effectively solves the problem of phenol-water azeotropy during solvent recovery in bisphenol A production units by coupling pervaporation and atmospheric distillation processes without using azeotropic agents, achieving high-purity and high-recovery separation of phenol and acetone. The pervaporation process utilizes the preferential permeability of water to dehydrate and concentrate the feed, significantly improving distillation efficiency; the atmospheric distillation process achieves complete separation and recovery of the target product with lower energy consumption.

[0069] Compared with traditional separation processes, the system has a simpler structure, is safer to operate, and produces cleaner products. It has excellent industrial adaptability and promotional value, and is particularly suitable for bisphenol A and other fine chemical processes involving phenol / water systems.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A recovery system of phenol and acetone in a bisphenol A production apparatus, characterized by, The system comprises a buffer tank, a liquid delivery pump, a pervaporation membrane device and an atmospheric distillation column connected in sequence, the pervaporation membrane device comprises a retentate side and a permeate side separated by a pervaporation membrane, and the retentate side is connected to the atmospheric distillation column.

2. The system for recovering phenol and acetone in a bisphenol A production device according to claim 1, characterized in that: the buffer tank is further connected to a bisphenol A reaction section; the top of the atmospheric distillation column is connected to an acetone recovery pipeline; the bottom of the atmospheric distillation column is connected to a phenol recovery pipeline.

3. The system for recovering phenol and acetone in a bisphenol A production device according to claim 1, characterized in that: the pervaporation membrane device comprises a plurality of pervaporation membrane units connected in series or in parallel; the permeate side of each pervaporation membrane unit is connected to a vacuum pump manifold.

4. The recovery system of phenol and acetone in a bisphenol A production apparatus according to claim 1, characterized by: The pervaporation membrane of the pervaporation membrane device is selected from any one of a molecular sieve membrane, a carboxymethyl cellulose membrane, a polyethyleneimine-tannin acid composite membrane, an amorphous silica membrane, a nanofiber composite polyacrylonitrile membrane or a modified PVA membrane; and the pervaporation membrane is a tubular membrane or a hollow fiber membrane.

5. A method for recovering phenol and acetone in a bisphenol A production apparatus, characterized by, The system for recovering phenol and acetone in a bisphenol A production device according to any one of claims 1 to 4 is used for recovery, and a mixture of phenol, acetone and water generated in a raw material refining and reaction section of a bisphenol A production process is sequentially introduced into the buffer tank, the liquid delivery pump, the pervaporation membrane device and the atmospheric distillation column, acetone is recovered at the top of the atmospheric distillation column, and phenol is recovered at the bottom of the atmospheric distillation column.

6. The method for recovering phenol and acetone in a bisphenol A production apparatus according to claim 5, characterized by, In the mixture of phenol, acetone and water: the weight percentage of phenol is 70-90%; the weight percentage of acetone is 2-15%.

7. The method for recovering phenol and acetone in a bisphenol A production apparatus according to claim 5, characterized by: In the pervaporation membrane device, the absolute pressure of the permeate side of the pervaporation membrane unit is 2000-5000 Pa.

8. The method for recovering phenol and acetone in a bisphenol A production apparatus according to claim 5, characterized by: In the pervaporation membrane device, the working temperature of the pervaporation membrane is between 70-130℃.

9. The method for recovering phenol and acetone in a bisphenol A production apparatus according to claim 5, characterized by: In the atmospheric distillation column, the top temperature is 55-70℃, the bottom temperature is 180-190℃, and the reflux ratio is 2-5.

10. The method for recovering phenol and acetone in a bisphenol A production device according to claim 5, characterized in that: the recovered acetone content is greater than or equal to 99 wt%; the recovered phenol content is greater than or equal to 98.5 wt %.

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