System and method for removing pentane from mother liquor in bisphenol A production process

Abstract

The invention provides a system and a method for depentanizing mother liquor in a bisphenol A production process. The system comprises a depentanizing tower and a pentane stripping tower, wherein a feed port of the depentanizer is used for inputting a first-section crystallization concentrated solution, and a discharge port at the top of the depentanizer is connected with the first condenser; a pentane-removed reaction mother solution is output from a tower kettle discharge port of the depentanizer; the depentanizer is connected with a thermosyphon reboiler, and a jet pump is arranged on a pipeline connecting the depentanizer and an inlet of the thermosyphon reboiler; the first condenser is connected with the chromatography device; the chromatographic device is provided with a first liquid outlet and a second liquid outlet, a first branch connected with the first liquid outlet is connected with the top of the depentanizer, and a second branch connected with the first liquid outlet is connected with a feed port of the pentane stripping tower; and outputting a phenol phase from a tower kettle of the pentane stripping tower. According to the system disclosed by the invention, normal operation of the thermosyphon reboiler and stable operation of the whole system are realized, so that the pressure at the top of the depentanizer tends to be stable.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a system and method for depentanizing mother liquor in a bisphenol A production process. Background Art

[0002] Bisphenol-A (BPA), molecular formula is C15H 16 O2, as a derivative of phenol and acetone, bisphenol A is one of the important organic chemical raw materials. It is mainly used in the production of various polymer materials such as polycarbonate, epoxy resin, polysulfone resin, polyaryl resin and unsaturated polyester resin. It can also be used to produce flame retardants, plasticizers, antioxidants, rubber anti-aging agents, coatings and other fine chemical products; among them, bisphenol A type polycarbonate has excellent physical and chemical properties and is one of the most widely used thermoplastic engineering plastics.

[0003] In the existing bisphenol A production, phenol and acetone are generally used as raw materials, and bisphenol A is obtained by condensation reaction under the action of catalysts such as sulfuric acid, hydrogen chloride or strong acidic cation exchange resin. The materials after the reaction are recycled, first-stage crystallization, filtration, melting, second-stage crystallization, filtration, melting, dephenolization and granulation to obtain bisphenol A products. The mother liquor of the first stage crystallization and the mother liquor of the second stage crystallization will be returned to the reaction process for recycling, but the mother liquor of the first stage crystallization often contains about 5wt%-15wt% of low-boiling alkanes with 4 to 6 carbon atoms, such as pentane, and the pentane contained in the mother liquor needs to be removed by a depentanizer to obtain a reaction mother liquor with pentane removed.

[0004] As one of the important auxiliary devices used in the production process of bisphenol A, the stability of the depentanizer operation is an important control link to ensure the continuity of the process. In the existing preparation of bisphenol A, the reboiler of the depentanizer adopts a thermosyphon reboiler. Establishing an efficient thermosyphon cycle is the key to providing effective energy supply for the operation of the entire depentanizer, and is also the key to improving the distillation and separation efficiency of bisphenol A. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention discloses a system and method for depentanizing mother liquor in a bisphenol A production process. The depentanizer in the system has a stable structure, and the method for depentanizing mother liquor in a bisphenol A production process using the system can operate stably, and pentane in a first-stage crystallization concentrated liquid in the bisphenol A production process can be efficiently removed and phenol therein can be recovered.

[0006] In order to achieve the above technical objectives, on the one hand, the present invention proposes a system for depentanizing mother liquor in a bisphenol A production process, the system comprising a depentanizer and a pentane stripping tower; wherein the feed port of the depentanizer is used to input a section of crystallized concentrated liquid, and the top discharge port thereof is connected to a first condenser; the reaction mother liquor from which pentane has been removed is discharged from the bottom discharge port of the depentanizer; the depentanizer is connected to a thermal syphon reboiler, and a jet pump is arranged on the pipeline connecting the depentanizer and the inlet of the thermal syphon reboiler; the first condenser is connected to a chromatograph; the chromatograph is provided with a first drain port and a second drain port, a first branch connected to the first drain port is connected to the top of the depentanizer, and a second branch connected to the first drain port is connected to the feed port of the pentane stripping tower; a phenol phase is discharged from the bottom of the pentane stripping tower; and a material containing pentane is discharged from the second drain port of the chromatograph.

[0007] The research and development team of the present invention encountered a condition in which the thermal siphon reboiler of the depentanizer in the mother liquor depentanizer unit could not operate normally during the actual operation of bisphenol A. The failure of the siphon reboiler caused the pressure at the top of the depentanizer to fluctuate frequently, resulting in poor mother liquor depentanization effect and inability to directly return to the upstream reaction process, which further hindered the continuous operation of the overall bisphenol A preparation process and affected the overall process progress.

[0008] In order to explore the reasons why the thermal syphon reboiler could not be put into use, the research and development team calculated and verified the tower diameter and tower height of the depentanizer, the area of ​​the thermal syphon reboiler, and the area of ​​the first condenser, but still could not solve the problem that the thermal syphon reboiler could not operate; further, the research and development team explored and verified the connection structure of the thermal syphon reboiler.

[0009] With the goal of establishing a stable thermosyphon cycle, technicians in this field have conducted a lot of research: In order to solve the problem that the thermosyphon reboiler of the demethanizer cannot be used, Chen Yuntao analyzed that the installation height of the reboiler is too low, resulting in a large circulation driving force, and optimized the circulation driving force and the pressure drop of each part. A regulating valve is added to the reboiler inlet pipeline to control the friction resistance of the reboiler inlet pipeline, and finally a thermosyphon cycle is established; Xu Lu, Ze Bin, Sun Tao, Shen Yang, etc. used Aspen Plus, Aspen EDR, HTRI and other simulation software to discuss the simulation and design process of the thermosyphon reboiler, studied the influence of key parameters such as the static pressure head of the tower kettle, installation height, reboiler structural dimensions, inlet and outlet pipe diameters on the stability of the thermosyphon cycle, and obtained the optimal reboiler structural parameters. The research and development team of the present invention found through experiments that the achievements of the above research and development team cannot solve the problem that the thermosyphon reboiler in the technical solution of the present invention cannot operate.

[0010] Based on a large amount of exploratory experimental data, the system for mother liquor depentanization in the bisphenol A production process of the present invention is provided with a jet pump on the pipeline connecting the depentanizer and the inlet of the thermosyphon reboiler, and a stably operating mother liquor depentanization unit is formed through the coordinated cooperation of the depentanizer and the pentane stripping tower, and a high-purity reaction mother liquor with pentane removed is extracted from the bottom of the depentanizer, and a phenol phase is output from the bottom of the pentane stripping tower, thereby realizing the recovery and utilization of phenol.

[0011] In a further example of the present invention, the structure of the depentanizer and technical features such as promoting the recovery of reaction aids are optimized, and the embodiment of the present invention shows the specific optimization process.

[0012] On the other hand, the present invention provides a method for depentanizing the mother liquor in the bisphenol A production process by using the above-mentioned system for depentanizing the mother liquor in the bisphenol A production process.

[0013] In a further example of the present invention, the control parameters and control conditions of the above method are explored and optimized, and the embodiment of the present invention shows the specific optimization process.

[0014] Compared with the prior art, the present invention has the following beneficial effects: in a system including a depentanizer and a pentane stripping tower, a jet pump is arranged on the input pipeline of the thermosyphon reboiler of the depentanizer, so that the normal operation of the thermosyphon reboiler and the stable operation of the overall system are achieved, so that the top pressure of the depentanizer tends to be stable, a high-purity reaction mother liquor from which pentane is removed is extracted from the bottom of the depentanizer, and a phenol phase is output from the bottom of the pentane stripping tower, so that the phenol is recovered and utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0016] Figure 1 A structural diagram showing a system for depentanization of mother liquor in the bisphenol A production process of the present invention;

[0017] Figure 2 Another structural diagram of the system for depentanizing the mother liquor in the bisphenol A production process of the present invention is shown.

[0018] The above drawings include the following reference numerals:

[0019] 1-depentanizer, 11-first condenser, 12-thermal syphon reboiler, 13-jet pump, 14-chromatograph, 15-buffer tank, 16-circulation pump, 17-second condenser, 2-pentane stripping tower, 3-pentane separation tower. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only used for more detailed description and should not be understood as limiting the present invention in any form, i.e., not intended to limit the scope of protection of the present invention.

[0021] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0022] The terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0023] Example 1

[0024] A system for depentanizing mother liquor in a bisphenol A production process, such as Figure 1 As shown, it includes a depentanizer 1 and a pentane stripping tower 2; wherein, the feed port of the depentanizer 1 is used to input a section of crystallized concentrated liquid, and its top discharge port is connected to a first condenser 11; the reaction mother liquor after depentane is discharged from the bottom discharge port of the depentanizer 1; the depentanizer 1 is connected to a thermal syphon reboiler 12, and a jet pump 13 is arranged on the pipeline connecting the depentanizer 1 and the inlet of the thermal syphon reboiler 12; the first condenser 11 is connected to a chromatograph 14; the chromatograph 14 is provided with a first liquid discharge port and a second liquid discharge port, the first branch connected to the first liquid discharge port is connected to the top of the depentanizer 1, and the second branch connected to the first liquid discharge port is connected to the feed port of the pentane stripping tower 2; the phenol phase is discharged from the bottom of the pentane stripping tower 2; the material containing pentane is discharged from the second liquid discharge port of the chromatograph 14.

[0025] Furthermore, the height difference between the reboiled material extraction port and the reboiled material return port of the depentanizer 1 is 0.5-2.5 m, which is conducive to the reboiled material being directly drawn out from the liquid seal of the downcomer on the bottom plate of the depentanizer 1, and returned to the bottom of the plate through the return port after passing through the reboiler, forming a natural circulation and improving the efficiency of heat exchange.

[0026] Furthermore, a buffer tank 15 and a circulation pump 16 are sequentially arranged on the pipeline connecting the depentanizer 1 and the jet pump 13, so that the reboiled material can be taken out from the liquid collecting box on the bottom plate of the depentanizer 1, flow to the buffer tank 15 by liquid gravity, and then enter the jet pump 13 by providing flow driving force of the reboiler circulation pipeline, and finally input into the thermal siphon reboiler 12 for vaporization.

[0027] Furthermore, the number of theoretical plates of the depentanizer 1 is 5-20. Optimizing the number of theoretical plates of the depentanizer 1 helps to improve the efficiency of removing pentane from the first-stage crystallization concentrate.

[0028] Furthermore, the theoretical plate number of the pentane stripping tower 2 is 10-30, thereby improving the phenol recovery rate.

[0029] Furthermore, the second condenser 17 is included, and the first crystallized concentrated liquid is input into the feed port of the depentanizer 1 through the second condenser 17; the tower bottom discharge port of the depentanizer 1 is connected to the second condenser 17. In the actual process, the temperature of the material taken out from the tower bottom of the depentanizer 1 is relatively high, and contains a large amount of available heat energy; by setting the second condenser 17, the reaction mother liquid from which pentane is removed taken out from the tower bottom of the depentanizer 1 can be heat exchanged with the first crystallized concentrated liquid of the new feed in the second condenser 17, thereby improving the processing efficiency of the subsequent depentanizer 1 and saving energy consumption.

[0030] Furthermore, a third condenser is also included, and the reaction mother liquid from which pentane is removed, output from the second condenser 17, can be returned to the upstream reaction process after heat exchange in the third condenser, thereby achieving full recovery of heat.

[0031] It should be noted that a non-condensable gas discharge branch is also provided, which is provided on the pipeline connecting the first condenser 11 and the chromatograph 14, or directly connected to the chromatograph 14, for discharging non-condensable gas in the material extracted from the top of the depentanizer 1.

[0032] It should be noted that the present invention does not limit the specific structure of the jet pump 13. The purpose of providing the jet pump 13 is to increase the flow driving force in the circulation pipeline of the thermal siphon reboiler 12. Therefore, technicians in this field can select the jet pump 13 that can achieve this effect according to actual needs, and the protection scope of the present invention is not limited thereby.

[0033] It should be noted that based on this embodiment, technicians in the field can set a suitable number of condensers and reboilers at suitable locations of the pentane stripping tower 2 and the pentane separation tower 3 through non-creative work, and the protection scope of the present invention is not limited thereby.

[0034] Example 2

[0035] Based on Example 1, Figure 2As shown, the system for depentanizing the mother liquor in the bisphenol A production process proposed in this embodiment also includes a pentane separation tower 3, the second liquid discharge port of the chromatograph 14 is connected to the feed port of the pentane separation tower 3, and the methyl mercaptan phase is extracted from the bottom of the pentane separation tower 3.

[0036] In the existing reaction system for preparing bisphenol A, in addition to adding reaction raw materials and catalysts, an appropriate amount of catalyst promoter can be added to improve the catalytic effect, such as methyl mercaptan as a commonly used promoter. In this embodiment, if the concentration of methyl mercaptan in the pentane phase output from the second liquid discharge port of the chromatograph 14 exceeds 2wt%, the material containing pentane can be input into the pentane separation tower 3, and methyl mercaptan can be extracted and recovered from the bottom of the tower after rectification and separation in the pentane separation tower 3, and the pentane phase can be extracted from the top of the tower and input into the subsequent process.

[0037] Furthermore, the number of theoretical plates of the pentane separation tower 3 is 5-20. Optimizing the number of theoretical plates of the pentane separation tower 3 is beneficial to improving the separation effect of methyl mercaptan and pentane.

[0038] Example 3

[0039] Based on the system for depentanizing mother liquor in the bisphenol A production process shown in Example 1, a method for depentanizing mother liquor in the bisphenol A production process is provided in this embodiment, specifically: in the reaction process of preparing bisphenol A, a crystallized concentrated liquid obtained after a first crystallization of the material after the condensation reaction of raw material phenol and acetone is distilled in a depentanizer 1 to remove pentane, and the reaction mother liquor after pentane removal is taken out from the bottom of the depentanizer 1, and this part of the material will be returned to the upstream reaction process; a mixed material containing pentane and phenol water is taken out from the top of the depentanizer 1, and the material is condensed by a first condenser 11 and then input into a chromatograph 14; the cavity of the chromatograph 14 is separated by a partition, and two liquid phases are output from a first discharge port and a second discharge port respectively; wherein, the first discharge port outputs a phenol water stream, and a part of the stream is discharged through the first discharge port. One branch refluxes to the top of the depentanizer 1, and the other part is input into the pentane stripping tower 2 through the second branch; through the distillation separation of the pentane stripping tower 2, the phenol phase is extracted from the bottom of the pentane stripping tower 2, and the phenol phase contains bisphenol A, phenol, water and heavy components. This part of the material can recover bisphenol A and separate to obtain phenol, and a mixed material containing pentane, acetone and a small amount of water is discharged from the top of the pentane stripping tower 2. This part of the material is subsequently separated to recover bisphenol A, and the separated pentane is recycled; and the second discharge port of the chromatograph 14 outputs the material containing pentane. In a further example of this embodiment, when the content of the catalyst auxiliary methyl mercaptan in this part of the material exceeds 2wt%, the catalyst auxiliary can be recycled through the distillation separation of the pentane separation tower 3, thereby reducing the production cost.

[0040] Optionally, the working pressure of the jet pump 13 is 200-210 MPa, and the flow rate is 100-120 m 3 / h. Optionally, the driving force of the liquid flow in the thermosyphon reboiler 12 is 4-5 kPa. This can meet the thermosyphon cycle operation requirements of the depentanizer 1 and promote the stable and continuous operation of the thermosyphon reboiler 12.

[0041] Optionally, the temperature of the first-stage crystallized concentrated liquid input to the depentanizer 1 is 45-55°C and the pressure is 450-550kPa. Further optionally, the temperature of the first-stage crystallized concentrated liquid input to the depentanizer 1 is 47-50°C and the pressure is 490-500kPa, which is beneficial to improve the separation effect of the depentanizer 1 and improve the operating efficiency of the overall mother liquor depentanizer unit.

[0042] Optionally, the top temperature of the depentanizer 1 is 40-50°C, the bottom temperature is 35-45°C, the operating pressure is 150-250kPa, and the reflux ratio is 0.8-1; further optionally, the top temperature of the depentanizer 1 is 42-45°C, the bottom temperature is 39-41°C, and the operating pressure is 180-200kPa.

[0043] Optionally, the top temperature of the pentane stripping tower 2 is 45-55°C, the bottom temperature is 40-50°C, the operating pressure is 450-550kPa, and the reflux ratio is 0.8-1; further optionally, the top temperature of the pentane stripping tower 2 is 48-52°C, the bottom temperature is 42-45°C, and the operating pressure is 490-500kPa.

[0044] Optionally, the top temperature of the pentane separation tower 3 is 45-55°C, the bottom temperature is 35-45°C, the operating pressure is 150-250Pa, and the reflux ratio is 0.8-1; further optionally, the top temperature of the pentane separation tower 3 is 47-50°C, the bottom temperature is 39-41°C, and the operating pressure is 180-200Pa.

[0045] Example 4

[0046] Based on the system for depentanization of mother liquor in the bisphenol A production process shown in Example 1, this example shows the process of depentanization of mother liquor in the bisphenol A production process under specific working conditions. It should be noted that this example is only a preferred demonstration and does not limit the scope of protection of the present invention.

[0047] The mother liquor depentanization unit of the bisphenol A preparation process of the depentanizer 1 in a chemical plant was taken as the research object. The abnormal working conditions of the thermosyphon reboiler 12 of the depentanizer 1 and the frequent fluctuation of the tower top pressure occurred.

[0048] On the one hand, in order to explore the cause of the abnormality, the research and development team of the present invention conducted the following explorations:

[0049] Exploration 1: Calculation of the tower diameter of the depentanizer 1. Based on the existing material balance, the tower diameter of the depentanizer 1 is calculated. CS-1 is the tower diameter calculation for the distillation section, the calculated tower diameter is 1450mm, and the actual tower diameter is 1600mm; CS-2 is the tower diameter calculation for the stripping section, the calculated tower diameter is 1836mm, and the actual tower diameter is 2300mm, indicating that the existing tower diameter meets the requirements.

[0050] Exploration 2: The thermal syphon reboiler 12 of the depentanizer 1 was calculated, and the actual area / calculated area = 2.14, indicating that the area of ​​the thermal syphon reboiler 12 meets the operating requirements.

[0051] Exploration 3: The first condenser 11 connected to the depentanizer 1 is calculated, and the actual area / calculated area = 3.84, indicating that the area of ​​the first condenser 11 meets the operating requirements.

[0052] Based on the above exploratory experiments, the R&D team speculated that the liquid driving force was insufficient to overcome the flow resistance of the reboiler and pipeline, resulting in abnormal operation of the thermal syphon reboiler 12; the steam in the reboiler could not heat the material, causing the bottom temperature of the tower to drop; even when the thermal syphon reboiler 12 was in forced circulation, the top pressure of the tower would fluctuate accordingly.

[0053] On the other hand, the present embodiment provides a system and method for depentanizing mother liquor in a bisphenol A production process, specifically: a crystallized concentrated liquid in a bisphenol A production process having a temperature of about 51°C and a pressure of about 500 kPa is input into the system of the present invention, and after being preheated by a second heat exchanger, the temperature reaches about 123°C, and is input into a depentanizer 1; a material containing pentane and phenol water at a temperature of about 43°C is taken out from the top of the depentanizer 1 and input into a first condenser 11, and a reaction mother liquor after pentane removal at a temperature of about 172°C is taken out from the bottom of the tower, and after heat exchange with a newly fed crystallized concentrated liquid in the second heat exchanger, the material is input into an upstream reaction process; the reflux ratio of the depentanizer 1 is 1.

[0054] The height difference between the reboiled material outlet and the reboiled material return outlet of the depentanizer 1 is 1m, the working pressure of the jet pump 13 is 200MPa, and the flow rate is 180m 3 / h; the feed temperature of the thermal syphon reboiler 12 is about 137.4°C, and the discharge temperature of the thermal syphon reboiler 12 is about 171.3°C.

[0055] The phenol water phase output from the first liquid discharge port of the chromatograph 14 is input into the pentane stripping tower 2, the top temperature of the pentane stripping tower 2 is 48°C, the bottom temperature is 42°C, the reflux ratio is 1, and phenol is taken out from the bottom of the pentane stripping tower 2 for recycling; the pentane phase output from the second liquid discharge port of the chromatograph 14 is input into the pentane separation tower 3, the top temperature of the pentane separation tower 3 is 48°C, the bottom temperature is 39°C, the reflux ratio is 1, and the catalyst auxiliary methyl mercaptan is taken out from the bottom of the pentane separation tower 3 for recycling.

[0056] The system for mother liquor depentanization in the bisphenol A production process of the present invention comprises a depentanizer 1 and a pentane stripping tower 2, and an ejector is arranged on the pipeline connecting the depentanizer 1 and the thermal syphon reboiler 12, so that the thermal syphon reboiler 12 can finally operate normally and the tower top pressure tends to be stable, thereby solving the problem that the thermal syphon reboiler 12 of the mother liquor depentanization unit in the bisphenol A production cannot operate normally.

[0057] It should be noted that the above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple improvements can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A system for depentanizing mother liquor in a bisphenol A production process, characterized in that: It comprises a depentane tower (1) and a pentane stripping tower (2); wherein, The feed inlet of the depentanizer (1) is used to input a section of crystallized concentrated liquid, and the top outlet is connected to the first condenser (11); the reaction mother liquid from which pentane has been removed is output from the bottom outlet of the depentanizer (1); The depentanizer (1) is connected to a thermosyphon reboiler (12), and a jet pump (13) is provided on a pipeline connecting the depentanizer (1) and an inlet of the thermosyphon reboiler (12); The first condenser (11) is connected to a chromatograph (14); the chromatograph (14) is provided with a first liquid discharge port and a second liquid discharge port, a first branch connected to the first liquid discharge port is connected to the top of the depentanizer (1), and a second branch connected to the first liquid discharge port is connected to the feed port of the pentane stripping tower (2); the phenol phase is output from the bottom of the pentane stripping tower (2); and the material containing pentane is output from the second liquid discharge port of the chromatograph (14).

2. The system for depentanizing mother liquor in the bisphenol A production process according to claim 1, characterized in that: The height difference between the reboiled material extraction port and the reboiled material return port of the depentanizer (1) is 0.5-2.5 m.

3. The system for depentanizing mother liquor in the bisphenol A production process according to claim 1, characterized in that: A buffer tank (15) and a circulation pump (16) are sequentially arranged on a pipeline connecting the depentanizer (1) and the jet pump (13).

4. The system for depentanizing mother liquor in the bisphenol A production process according to claim 1, characterized in that: The number of theoretical plates of the depentanizer (1) is 5-20; And / or, the theoretical plate number of the pentane stripping tower (2) is 10-30.

5. The system for depentanizing mother liquor in the bisphenol A production process according to claim 1, characterized in that: It also includes a pentane separation tower (3), wherein the second liquid discharge port of the chromatograph (14) is connected to the feed port of the pentane separation tower (3), and the methyl mercaptan phase is extracted from the bottom of the pentane separation tower (3); Preferably, the theoretical plate number of the pentane separation tower (3) is 5-20.

6. The system for depentanizing mother liquor in the bisphenol A production process according to claim 1, characterized in that: It also comprises a second condenser (17), through which the first stage of crystallized concentrated liquid is input into the feed port of the depentanizer (1); the bottom discharge port of the depentanizer (1) is connected to the second condenser (17).

7. A method for depentanizing mother liquor in a bisphenol A production process, characterized in that: The method is carried out in a system for depentanizing mother liquor in the bisphenol A production process according to any one of claims 1 to 6.

8. The method for depentanizing mother liquor in the production process of bisphenol A according to claim 7, characterized in that: The working pressure of the jet pump (13) is 200-210 MPa, and the flow rate is 100-120 m 3 / h; And / or, the driving force for liquid flow in the thermosyphon reboiler (12) is 4-5 kPa.

9. The method for depentanizing mother liquor in the production process of bisphenol A according to claim 7, characterized in that: The temperature of the first stage crystallized concentrated liquid input into the depentanizer (1) is 45-55°C and the pressure is 450-550 kPa.

10. The method for depentanizing mother liquor in the production process of bisphenol A according to claim 7, characterized in that: The depentanizer (1) has a top temperature of 40-50°C, a bottom temperature of 35-45°C, an operating pressure of 150-250 kPa, and a reflux ratio of 0.8-1; and / or, the top temperature of the pentane stripping tower (2) is 45-55° C., the bottom temperature is 40-50° C., the operating pressure is 450-550 kPa, and the reflux ratio is 0.8-1; And / or, the top temperature of the pentane separation tower (3) is 45-55°C, the bottom temperature is 35-45°C, the operating pressure is 150-250 Pa, and the reflux ratio is 0.8-1.

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