Method and apparatus for producing bisphenol a

Abstract

To provide a method and an apparatus for producing bisphenol A.SOLUTION: Reaction systems at each stage include a cooler and four reactors at four stages, a bisphenol A synthesis resin catalyst is filled into the reactors before start-up operation of the system, the filling ratio of the catalyst of the reactor of a section 1 is 1 / 3, the filling ratio of the reactor of a section 2 is 2 / 3, and the filling ratios of the reactor of a section 3 and the reactor of a section 4 are 1, series operation of the three reactors is controlled by a valve, when the remaining catalyst life is 1 / 3, every time the system is operated, the system separates the reactor whose catalyst deactivates, performs such control as to switch the reactor to a stand-by reactor, and maintains the serial operation of the three reactors, the method provides larger space speed, eliminates the effect of external diffusion, is useful for obtaining a higher product yield, can periodically evaluate and inspect catalyst activity without causing the waste of the catalyst in a test run period of the system, and can improve economical benefits of production.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and apparatus for producing bisphenol A, and particularly to technical means for the series operation of reactors and a catalyst filling ratio scheme in the reactor before startup.

Background Art

[0002] Bisphenol A is produced by subjecting acetone and excess phenol to a condensation reaction under appropriate temperature, pressure, and catalysis. This reaction is an exothermic reaction and water is generated. Non-Patent Document 1 states that the heat of reaction for the condensation reaction of phenol and acetone is 98 kcal / kg. To maintain a predetermined reaction temperature, a circulating heat removal pump is provided at each stage of the reaction system, and a part of the heat is removed by returning the excess phenol raw material to the reaction system. It is mentioned that the reaction is maintained at an appropriate temperature. To promote the reaction and reduce the harmful effect of water on the catalyst, Mitsubishi Chemical Corporation (Chiyoda Corporation: Advanced Process for Production of BPA, CT-BISA Process, 1996) sends the unreacted acetone, water, and phenol in the reaction mixture to three distillation towers for distillation separation. The separated acetone and phenol are recycled to the synthesis reactor to participate in the reaction, and water is discharged as waste from the bottom of the distillation tower. However, when using multiple distillation towers to separate the reactants one by one, a lot of energy and economic losses occur. The present invention designs an inter-stage dehydration system that removes the water generated in the first-stage reaction system at once by flash evaporation, ensuring the quality of the product while reducing energy loss.

[0003] GE (Bisphenol A and Alkylated Phenols, PEP Report, No. 1921988 Dec) conducted the reaction using a single two-layer fixed-bed reactor. The one-pass conversion rates of the obtained acetone and phenol were approximately 50% and 10% respectively. In the case of phenol, the total BPA yield was 91%, and the maximum processing capacity of a single unit reactor was about 240,000 tons per year, which does not meet the development trend of large-scale industrial production. To further improve the reaction conversion rate and selectivity, the present invention designed three circulating fixed-bed reactors connected in series to increase the space velocity and the driving force of the reaction to obtain a higher conversion rate.

[0004] In the industry, for the synthesis of bisphenol A, single or parallel fixed-bed reactors filled with catalysts are often used, and the bisphenol A synthesis catalyst is mainly an ion exchange resin. When it is found that the quality of the product does not meet the standards during the startup of the system, it is necessary to remove all the filled catalysts and send them for evaluation and analysis, which causes a great waste of human and material resources. Patent Document 1 discloses a method and device for exchanging catalysts in the bisphenol A synthesis process. In this method, multiple parallel reactors are connected to a condensation area and an isomerization area respectively in a multiple reactor parallel method. When the quality of the catalyst in the condensation reaction area does not meet the requirements, the catalyst in the reactor is taken out and replaced with a new reformed catalyst, and then switched to the isomerization area for continuous use. This method cannot solve the problem of waste that all catalysts need to be exchanged when the quality of the product is unstable during the trial operation period of the system. When problems occur in the quality of the product during the trial operation period, it is necessary to exchange all the catalysts filled in the parallel reactors, which causes great economic losses. The present invention can prevent the above problems, and it is particularly advantageous to avoid economic losses, especially in the case of large-scale manufacturing equipment.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Documents

[0006] [Non-Patent Document 1] "Bisphenol A" compiled and translated by Liang Shuxiang [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] An object of the present invention is to provide a method and apparatus for continuously and stably producing bisphenol A. A reaction system is constructed in which three reactors are connected in series using a resin catalyst. The reaction system can provide higher reaction selectivity and conversion rate, and is also useful for expanding production capacity. By the process configuration of the reaction system and the filling scheme of the resin catalyst into the reactor, not only the problem of catalyst waste when the product quality does not meet the standard during the start-up period of the system is solved, but also the problems of production capacity reduction and bisphenol A selectivity reduction due to partial deactivation of the resin catalyst can be avoided, and the discharge of three kinds of wastes can be effectively reduced. [Means for Solving the Problems]

[0008] The technical means of the present invention are as follows.

[0009] A method for producing bisphenol A, comprising a two-stage reaction system and an inter-stage dehydration system. Each stage of the reaction system includes a cooler and four reactors in four sections. Before the start-up operation of the system, a bisphenol A synthetic resin catalyst is filled into the reactors. The filling ratio of the catalyst is 1 / 3 for the reactor in section 1, 2 / 3 for the reactor in section 2, and 1 for the reactors in section 3 and section 4. The reactors in section 1, section 2, and section 3 are operated in series by valve control. The reaction raw material is charged from the inlet of the reactor in section 1, and the product is withdrawn from the outlet of the reactor in section 3.

[0010] In the method for producing bisphenol A, any three reactors are controlled to achieve series operation, and the other reactors can be independently stopped without affecting the flow of the entire process. The filling ratios of the catalysts in the reactors before the start-up operation of the system are as follows: the reactor in section 1 is 1 / 3, the reactor in section 2 is 2 / 3, the reactor in section 3 is 1, and the reactor in section 4 is 1. After the start-up operation, every 1 / 3 of the catalyst usage cycle, the reactor in which the catalyst has been deactivated is disconnected by valve control, and the series operation of the remaining three reactors is controlled to achieve continuous production. v

[0011] In the method for producing bisphenol A, the reactor switching method during the operation period of the system is as follows.

[0012] 1) Acetone, excessive phenol, and the first-stage reaction liquid circulation stream are cooled to the reaction temperature and sent to the first-stage reaction system for reaction to produce bisphenol A. A mixed liquid of bisphenol A, unreacted phenol, and by-products is obtained. Partially recycled to the first-stage reaction system according to the ratio so that the temperature of the raw materials at the outlet of the first-stage reaction system drops below 76°C. The reaction liquid sent out from the first-stage reaction system and the two-stage reaction circulation liquid enter the inter-stage dehydration system. After preheating and passing through vacuum flash evaporation and dehydration, they are sent into the second-stage reaction system. After being cooled together with the fresh acetone supplied at the supply point of the second-stage reaction system, they are reacted in the second-stage reaction system to obtain bisphenol A. The bisphenol A reaction liquid after the reaction is divided into two streams. One stream is recycled to the inter-stage dehydration system, and the ratio of the stream is adjusted so that the temperature of the raw materials at the outlet of the second-stage reactor drops below 80°C. The other stream is withdrawn and sent to the adsorption column.

[0013] 2) When the catalyst in the reactor of Section 1 loses its catalytic activity, the lifespan of the catalyst in the reactor of Section 2 with a catalyst filling ratio of 2 / 3 becomes 1 / 3, and the lifespan of the catalyst in the reactor of Section 3 with a catalyst filling ratio of 1 becomes 2 / 3. At this time, the reactor of Section 1 where the catalyst has been deactivated is disconnected by valve control, and the operation is switched to the series operation of the reactor of Section 4, the reactor of Section 2, and the reactor of Section 3. The reaction raw material enters from the reactor of Section 2, and the reaction product is controlled to be withdrawn from the reactor of Section 4. The deactivated catalyst in the disconnected reactor of Section 1 is discharged and processed, filled with a new catalyst with a filling ratio of 1, and prepared for later use.

[0014] 3) When the catalyst in the reactor of Section 2 loses its catalytic activity, the reactor of Section 2 where the catalyst has been deactivated is disconnected by valve control, and the operation is switched to the series operation of the reactor of Section 1, the reactor of Section 3, and the reactor of Section 4. The deactivated catalyst in the disconnected reactor of Section 2 is discharged and processed, filled with a new catalyst, and prepared for later use. The raw material is controlled to enter from the inlet of the reactor of Section 3 and be withdrawn from the outlet of the reactor of Section 1.

[0015] 4) When the catalyst in the reactor of Section 3 loses its catalytic activity, the reactor of Section 3 where the catalyst has been deactivated is disconnected by valve control, and the operation is switched to the series operation of the reactor of Section 2, the reactor of Section 1, and the reactor of Section 4. The deactivated catalyst in the disconnected reactor of Section 3 is discharged and processed, filled with a new catalyst, and prepared for later use. The raw material is controlled to enter from the inlet of the reactor of Section 4 and be withdrawn from the outlet of the reactor of Section 2.

[0016] 5) When the catalyst in the reactor of Section 4 loses its catalytic activity, through valve control, the reactor of Section 4 where the catalyst has deactivated is disconnected, and the operation is switched to the series operation of the reactor of Section 3 and the reactors of Section 1 and Section 2. The deactivated catalyst in the disconnected reactor of Section 4 is discharged and processed, and the reactor is filled with new catalyst and prepared for later use. The raw material is controlled to enter from the inlet of the reactor of Section 1 and be withdrawn from the outlet of the reactor of Section 3, and the operation mode of the system returns to the starting state.

[0017] The catalyst is a bisphenol A synthesis resin catalyst and contains a mercapto-modified strongly acidic cation exchange resin.

[0018] An apparatus for implementing the method for producing bisphenol A according to the present invention, wherein each reactor is provided with a raw material inlet and a product outlet, the inlet of each reactor in the first-stage reaction system is connected to the outlet of the first-stage cooler, the outlet of each reactor is respectively connected to the inlet of the first-stage circulation heat removal pump and the inlet of the inter-stage preheater, the outlet of the reactor in the first-stage section 1 is connected to the inlet of the reactor in the first-stage section 2, the outlet of the reactor in the first-stage section 2 is connected to the inlet of the reactor in the first-stage section 3, the outlet of the reactor in the first-stage section 3 is connected to the inlet of the reactor in the first-stage section 4, the outlet of the reactor in the first-stage section 4 is connected to the inlet of the reactor in the first-stage section 1, the outlet of the first-stage circulation pump is connected to the inlet of the first-stage cooler, the outlet of the inter-stage preheater is connected to the inlet of the flash evaporator, the vapor-phase outlet of the flash evaporator is connected to the inlet of the first-stage condenser, the outlet of the first-stage condenser is respectively connected to the recovery system and the inlet of the second-stage condenser, the outlet of the second-stage condenser is respectively connected to the recovery system and the vacuum unit, the liquid-phase outlet of the flash evaporator is connected to the inlet of the flash evaporation liquid pump, the outlet of the flash evaporation liquid pump is connected to the inlet of the second-stage cooler, the acetone raw material pipeline is respectively connected to the inlet of the first-stage cooler and the inlet of the second-stage cooler, the phenol raw material pipeline is connected to the inlet of the first-stage cooler, the inlet of each reactor in the second-stage reaction system is connected to the outlet of the second-stage cooler, the outlet of each reactor is respectively connected to the inlet of the inter-stage preheater and the inlet of the adsorption column, the outlet of the reactor in the second-stage section 1 is connected to the inlet of the reactor in the second-stage section 2, the outlet of the reactor in the second-stage section 2 is connected to the inlet of the reactor in the second-stage section 3, the outlet of the reactor in the second-stage section 3 is connected to the inlet of the reactor in the second-stage section 4, the outlet of the reactor in the second-stage section 4 is connected to the inlet of the reactor in the second-stage section 1, the pipelines in each stage of the reaction system are controlled to be opened and closed by valves, any three reactors can be connected in series, and the outlet of the adsorption column is connected to the inlet pipeline of the concentrated bisphenol A system.

[0019] In the method for synthesizing bisphenol A according to the present invention, The outlet temperature on the temperature reduction side of the first-stage cooler is 65 - 70°C, the unit bed pressure loss of the first-stage reactor in series is 15 - 30 kPa / m, the outlet temperature of the first-stage reactor in series is less than 76°C, and the outlet temperature of the first-stage circulation pump is 72 - 76°C. The outlet temperature on the temperature reduction side of the second-stage cooler is 65 - 70°C, the unit bed pressure loss of the second-stage reactor in series is 7 - 28 kPa / m, and the outlet temperature of the second-stage reactor in series is 72 - 80°C. The outlet temperature on the temperature increase side of the inter-stage preheater is 85 - 90°C, and the pressure of the dehydration flash evaporator is 3 - 7 kPaA.

[0020] The flow rate ratio of the raw material flow at the outlet of the second-stage reactor entering the inter-stage dehydration system to the raw material flow at the outlet of the second-stage reactor sent to the adsorption column is 0.8:1 - 1:1.

Advantages of the Invention

[0021] The advantages and beneficial effects of the present invention are as follows: The present invention relates to a method and apparatus for producing novel bisphenol A. Its advantages are to reduce the influence of external diffusion on the reaction, provide higher reaction selectivity and conversion rate, expand the production capacity of the process, remove part of the reaction heat by raw material circulation, and stably carry out the bisphenol A synthesis reaction under appropriate temperature conditions. The inter-stage dehydration system removes the water generated by the reaction, promotes the reaction to proceed in the forward direction, and it is beneficial to improve the selectivity and yield of bisphenol A. The scheme of filling the catalyst in proportion before the start-up of the system can solve the problem of waste caused by catalyst disposal when the product quality does not meet the standards during the start-up period of the system. Moreover, this production method and apparatus ensure that the reaction proceeds continuously and stably under high catalyst activity, prevent the reduction of the production capacity of the apparatus and the reduction of the selectivity of bisphenol A, and can effectively reduce the discharge amount of three kinds of wastes. In addition, the anion resin adsorption column can effectively prevent the acid content in the reaction solution and control the acidity of the system.

Brief Description of the Drawings

[0022]

Figure 1

Embodiments for Carrying out the Invention

[0023] Hereinafter, the present invention will be further described with reference to FIG. 1 and specific examples. The following examples are only used to interpret the present invention and do not limit the scope of the present invention. It should not be understood as a limitation to the protection scope of the present invention.

[0024] Taking the most commonly used catalyst for synthesizing bisphenol A, "mercapto-modified strongly acidic cation exchange resin", as an example, its life cycle is 12 months.

[0025] The present invention provides a method for synthesizing bisphenol A including the following technical means, (1) A step of confirming the catalyst filling ratio in the reactor before the start-up of the system, (2) After cooling acetone and excess phenol, feeding them into the first-stage reaction system to react to produce bisphenol A, (3) A part of the product of the first-stage reaction system is returned to the first-stage reaction system, a stream is extracted and fed into an inter-stage dehydration system for flash evaporation and dehydration, (4) A step of replenishing acetone and reacting it in the second-stage reaction system to produce bisphenol A, and (5) A step of serially operating the reactors in the two-stage reaction system and switching the reactors every time they are operated for a certain period of time.

[0026] The apparatus for implementing the novel method for producing bisphenol A provided by the present invention includes a reactor 101 in the first-stage section 1, a reactor 102 in the first-stage section 2, a reactor 103 in the first-stage section 3, a reactor 104 in the first-stage section 4, a reactor 105 in the second-stage section 1, a reactor 106 in the second-stage section 2, a reactor 107 in the second-stage section 3, a reactor 108 in the second-stage section 4, a first-stage cooler 109, an inter-stage preheater 110, a second-stage cooler 111, a first-stage condenser 112, a second-stage condenser 113, a flash evaporator 114, a first-stage circulation pump 115, a flash evaporation liquid pump 116, and an adsorption column 117.

[0027] The two-stage reaction system connection method is such that each reactor is provided with a raw material inlet and a product outlet. The inlet of each reactor in the first-stage reaction system is connected to the outlet of the first-stage cooler 109. The outlets of each reactor are respectively connected to the inlet of the first-stage circulation heat removal pump 115 and the inlet of the inter-stage preheater 110. The outlet of the reactor 101 in the first-stage section 1 is connected to the inlet of the reactor 102 in the first-stage section 2. The outlet of the reactor 102 in the first-stage section 2 is connected to the inlet of the reactor 103 in the first-stage section 3. The outlet of the reactor 103 in the first-stage section 3 is connected to the inlet of the reactor 104 in the first-stage section 4. The outlet of the reactor 104 in the first-stage section 4 is connected to the inlet of the reactor 101 in the first-stage section 1. The outlet of the first-stage circulation pump 115 is connected to the inlet of the first-stage cooler 109. The outlet of the inter-stage preheater 110 is connected to the inlet of the flash evaporator 114. The vapor-phase outlet of the flash evaporator 114 is connected to the inlet of the first-stage condenser 112. The outlet of the first-stage condenser 112 is respectively connected to the recovery system and the inlet of the second-stage condenser 113. The outlet of the second-stage condenser 113 is respectively connected to the recovery system and the vacuum unit. The liquid-phase outlet of the flash evaporator 114 is connected to the inlet of the flash evaporation liquid pump 116. The outlet of the flash evaporation liquid pump 116 is connected to the inlet of the second-stage cooler 111. The acetone raw material pipeline is respectively connected to the inlet of the first-stage cooler 109 and the inlet of the second-stage cooler 111. The phenol raw material pipeline is connected to the inlet of the first-stage cooler 109. The inlet of each reactor in the second-stage reaction system is connected to the outlet of the second-stage cooler 111. The outlets of each reactor are respectively connected to the inlet of the inter-stage preheater 110 and the inlet of the adsorption column 117. The outlet of the reactor 105 in the second-stage section 1 is connected to the inlet of the reactor 106 in the second-stage section 2. The outlet of the reactor 106 in the second-stage section 2 is connected to the inlet of the reactor 107 in the second-stage section 3. The outlet of the reactor 107 in the second-stage section 3 is connected to the inlet of the reactor 108 in the second-stage section 4. The outlet of the reactor 108 in the second-stage section 4 is connected to the inlet of the reactor 105 in the second-stage section 1. The pipelines in each stage of the subsequent reaction system are controlled to be opened and closed by valves, and any three reactors can be connected in series. The outlet of the adsorption column 117 is connected to the inlet pipeline of the concentrated bisphenol A system. This is the feature.

[0028] In the above technical means, a specific embodiment of step (1) is that before the startup of the system, a mercapto-modified strongly acidic cation exchange resin catalyst for bisphenol A synthesis is pre-filled in the reactors in the two-stage reaction system. The filling ratios are as follows: for the reactors in the first-stage section 1, it is 1 / 3; for the reactors in the first-stage section 2, it is 2 / 3; for the reactors in the first-stage section 3, it is 1; for the reactors in the first-stage section 4, it is 1. For the reactors in the second-stage section 1, it is 1 / 3; for the reactors in the second-stage section 2, it is 2 / 3; for the reactors in the second-stage section 3, it is 1; for the reactors in the second-stage section 4, it is 1.

[0029] In the above technical means, a specific embodiment of step (2) is that acetone and excessive phenol are introduced into a cooler and cooled to 70 °C, and then sent to the first-stage reaction system for a condensation reaction to produce a bisphenol A mixture.

[0030] In the above technical means, a specific embodiment of step (3) is that a part of the mixture in step (2) is sent to the first-stage circulation pump and returned to the first-stage reaction system to continue to participate in the reaction. The flow rate ratio is adjusted so that the outlet temperature of the first-stage circulation pump is less than 76 °C. The remaining mixture is preheated to 85 °C in an inter-stage preheater and then sent to a dehydration flash evaporator for dehydration.

[0031] In the above technical means, a specific embodiment of step (4) is that the raw material flow at the liquid phase outlet of the flash evaporator is sent to the inlet of the flash evaporation liquid pump. After the raw material flow at the outlet of the flash evaporation liquid pump is mixed with the acetone raw material, it is cooled to 70 °C in the second-stage cooler and then enters the second-stage reactor for reaction.

[0032] In the above technical means, a specific embodiment of step (5) is Four months after the start-up operation of the system, in the two-stage reaction system, the catalyst in the reactor of section 1 with a catalyst filling ratio of 1 / 3 before start-up lost its catalytic activity. The remaining catalyst life in the reactor of section 2 with a catalyst filling ratio of 2 / 3 was 4 months, the remaining catalyst life in the reactor of section 3 with a catalyst filling ratio of 1 was 8 months, and the remaining catalyst life in the reactor of section 4 was 12 months. At this time, the reactor of section 1 where the catalyst was deactivated was separated by valve control, and the operation was switched to the series operation of the reactor of section 4, the reactor of section 2, and the reactor of section 3. The reaction raw material was controlled to enter from the reactor of section 2 with a remaining catalyst life of 4 months, and the reaction product was withdrawn from the reactor of section 4 with a remaining catalyst life of 12 months. The deactivated catalyst in the separated reactor of section 1 was discharged and processed, and a new mercapto-modified strongly acidic cation exchange resin catalyst was fully filled and prepared for later use.

[0033] Eight months after the start-up operation of the system, the catalyst in the reactor of section 2 lost its catalytic activity. The reactor of section 2 where the catalyst was deactivated was separated by valve control, and the operation was switched to the series operation of the reactor of section 1, the reactor of section 3, and the reactor of section 4. The deactivated catalyst in the separated reactor of section 2 was discharged and processed, and a new mercapto-modified strongly acidic cation exchange resin catalyst was fully filled and prepared for later use. The raw material was controlled to enter from the inlet of the reactor of section 3 and be withdrawn from the outlet of the reactor of section 1.

[0034] Twelve months after the start-up operation of the system, the catalyst in the reactor of section 3 lost its catalytic activity. The reactor of section 3 where the catalyst was deactivated was separated by valve control, and the operation was switched to the series operation of the reactor of section 2, the reactor of section 1, and the reactor of section 4. After the deactivated catalyst in the separated reactor of section 3 was discharged, a new catalyst was fully filled and prepared for later use. The raw material was controlled to enter from the inlet of the reactor of section 4 and be withdrawn from the outlet of the reactor of section 2.

[0035] Sixteen months after the start-up operation of the system, the catalyst in the reactor of Section 4 lost its catalytic activity. The reactor of Section 4 where the catalyst was deactivated was disconnected by valve control, and the operation was switched to the series operation of the reactor of Section 3, the reactor of Section 1, and the reactor of Section 2. The deactivated catalyst in the disconnected reactor of Section 4 was discharged and processed, and was prepared for later use. The raw material entered from the inlet of the reactor of Section 1 and was controlled to be withdrawn from the outlet of the reactor of Section 3, and the operation mode of the system returned to the state before start-up.

[0036] In this way, the reactor in which the catalyst was deactivated was disconnected every four months, the catalyst in it was discharged and processed, and was prepared for later use. As shown in the schematic flow chart of the bisphenol A synthesis process of the present invention in Figure 1, the valve was controlled to maintain the series operation of the remaining three reactors, and continuous and stable process production was realized.

[0037] The outlet temperature on the temperature reduction side of the first-stage cooler is 65 - 70°C, the unit bed pressure loss of the series first-stage reactor is 15 - 30 kPa / m, the outlet temperature of the series first-stage reactor is less than 76°C, the outlet temperature of the first-stage circulation pump is 72 - 76°C, the outlet temperature on the temperature reduction side of the second-stage cooler is 65 - 70°C, the unit bed pressure loss of the series second-stage reactor is 7 - 28 kPa / m, the outlet temperature of the series second-stage reactor is 72 - 80°C, the outlet temperature on the temperature increase side of the inter-stage preheater is 85 - 90°C, the pressure of the dehydration flash evaporator is 3 - 7 kPaA, and the flow rate ratio of the raw material flow at the outlet of the second-stage reactor entering the inter-stage dehydration system to the raw material flow at the outlet of the second-stage reactor sent to the adsorption column is 0.8:1 - 1:1.

Example

[0038] Hereinafter, the specific implementation process of the method of the present application will be described by giving specific examples.

[0039] (Example 1) When the system starts up, the raw material phenol, the raw material acetone, and the circulating product of the first-stage reaction system are mixed. After being cooled to 65°C by the first-stage cooler 109, they sequentially flow into the reactors 101 of the first-stage section 1, the reactor 102 of the first-stage section 2, and the reactor 103 of the first-stage section 3 in series, and a condensation reaction occurs. The catalyst filling ratio of the reactor 101 in the first-stage section 1 is 1 / 3, the catalyst filling ratio of the reactor 102 in the first-stage section 2 is 2 / 3, the catalyst filling of the reactor 103 in the first-stage section 3 is 1, and the catalyst filling ratio of the reactor 104 in the first-stage section 4 is 1. By valve control, the reactor 104 in the first-stage section 4 is temporarily disconnected from the reaction system. The unit bed pressure loss of the three reactors in series is 15 kPa / m, the outlet raw material temperature of the reactor in the first-stage section 3 is 76°C, and the outlet products of the reactor 103 in the first-stage section 3 enter the first-stage circulation pump 115 and the inter-stage preheater 110 at a ratio of 2:1 respectively. The outlet temperature of the first-stage circulation pump is 73°C. The reaction liquid heated to 85°C by the inter-stage preheater 110 enters the flash evaporation tank 114, where it is flash evaporated and dehydrated under a pressure of 3 kPaA. The by-products of the vapor-phase outlet water and light components of the flash evaporation tank 114 enter the recovery system area after passing through the first-stage condenser 112 and the second-stage condenser 113. The liquid-phase outlet product of the flash evaporation tank 114 passes through the flash evaporation liquid pump and is then mixed with the replenished fresh acetone, and then sent to the second-stage cooler 111 to be cooled to 65°C. After cooling, the reaction liquid sequentially flows into the reactors 105 of the second-stage section 1, the reactor 106 of the second-stage section 2, and the reactor 107 of the second-stage section 3 in series, and a condensation reaction occurs. The catalyst filling ratio of the reactor 105 in the second-stage section 1 is 1 / 3, the catalyst filling ratio of the reactor 106 in the second-stage section 2 is 2 / 3, the catalyst filling ratio of the reactor 107 in the second-stage section 3 is 1, and the catalyst filling ratio of the reactor 108 in the second-stage section 4 is 1. By valve control, the pipeline connected to the reactor 108 in the second-stage section 4 is disconnected, and the reactor 108 in the second-stage section 4 is put on standby alone. The unit bed pressure loss of the three reactors in series is 7 kPa / m, and the outlet raw material temperature of the reactor in the second-stage section 3 is 80°C.The outlet product of reactor 107 in section 3 of the second stage entered the inlet of the inter-stage preheater 110 and the inlet of the adsorption column 117 at a ratio of 0.8:1.

[0040] Four months after the operation of the system, the catalysts in reactor 101 of section 1 of the first stage and reactor 105 of section 1 of the second stage with a catalyst filling ratio of 1 / 3 lost their catalytic activity. The remaining service life of the catalysts in reactor 102 of section 2 of the first stage and reactor 106 of section 2 of the second stage with a catalyst filling ratio of 2 / 3 was 4 months. The remaining service life of the catalysts in reactor 103 of section 3 of the first stage and reactor 107 of section 3 of the second stage with a catalyst filling ratio of 1 was 8 months. The remaining service life of the catalysts in reactor 104 of section 4 of the first stage and reactor 108 of section 4 of the second stage was 12 months. At this time, by valve control, reactors 101 of section 1 of the first stage and 105 of section 1 of the second stage where the catalysts were deactivated were disconnected, and reactor 104 of section 4 of the first stage was started and directly connected to reactor 102 of section 2 of the first stage and reactor 103 of section 3 of the first stage. The raw material inlet valve of reactor 102 of section 2 of the first stage and the product outlet valve of reactor 104 of section 4 of the first stage were opened to control the raw material inflow and product outflow of the first stage reaction system. In the second stage reaction system, reactor 108 of section 4 of the second stage was started and connected in series with reactor 106 of section 2 of the second stage and reactor 107 of section 3 of the second stage. The inlet valve of reactor 106 of section 2 of the second stage and the outlet valve of reactor 108 of section 4 of the second stage were opened to control the raw material inflow and product outflow of the second stage reaction system. The deactivated catalysts in the disconnected reactors 101 of section 1 of the first stage and 105 of section 1 of the second stage were evaluated, discharged and processed, and filled with new catalysts (ratio is 1) to be prepared for later use.

[0041] Eight months after the operation of the system, reactors 102 in the first-stage section 2 and reactor 106 in the second-stage section 2 where the catalyst was deactivated by valve control were disconnected. Reactor 101 in the first-stage section 1 was connected in series with reactor 103 in the first-stage section 3 and reactor 104 in the first-stage section 4. The raw material inlet valve of reactor 103 in the first-stage section 3 and the product outlet valve of reactor 101 in the first-stage section 1 were opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 105 in the second-stage section 1 was connected in series with reactor 107 in the second-stage section 3 and reactor 108 in the second-stage section 4. The raw material inlet valve of reactor 107 in the second-stage section 3 and the product outlet valve of reactor 105 in the second-stage section 1 were opened to control the raw material inflow and product outflow of the second-stage reaction system. After discharging the deactivated catalyst in reactors 102 in the first-stage section 2 and reactor 106 in the second-stage section 2, new catalyst (ratio is 1) was fully filled and prepared for later use.

[0042] Twelve months after the operation of the system, reactors 103 in the first-stage section 3 and reactor 107 in the second-stage section 3 where the catalyst was deactivated by valve control were disconnected. Reactor 102 in the first-stage section 2 was connected in series with reactor 104 in the first-stage section 4 and reactor 101 in the first-stage section 1. The raw material inlet valve of reactor 104 in the first-stage section 4 and the product outlet valve of reactor 102 in the first-stage section 2 were opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 106 in the second-stage section 2 was connected in series with reactor 108 in the second-stage section 4 and reactor 105 in the second-stage section 1. The raw material inlet valve of reactor 108 in the second-stage section 4 and the product outlet valve of reactor 106 in the second-stage section 2 were opened to control the raw material inflow and product outflow of the second-stage reaction system. After discharging the deactivated catalyst in reactors 103 in the first-stage section 3 and reactor 107 in the second-stage section 3, new catalyst (ratio is 1) was fully filled and prepared for later use.

[0043] Sixteen months after the system started operation, reactors 104 in the first-stage section 4 and 108 in the second-stage section 4 with deactivated catalysts due to valve control were disconnected. Reactor 103 in the first-stage section 3 was connected in series with reactor 101 in the first-stage section 1 and reactor 102 in the first-stage section 2. The raw material inlet valve of reactor 101 in the first-stage section 1 and the product outlet valve of reactor 103 in the first-stage section 3 were opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 107 in the second-stage section 3 was connected in series with reactor 105 in the second-stage section 1 and reactor 106 in the second-stage section 2. The raw material inlet valve of reactor 105 in the second-stage section 1 and the product outlet valve of reactor 107 in the second-stage section 3 were opened to control the raw material inflow and product outflow of the second-stage reaction system. After discharging the deactivated catalysts in reactors 104 in the first-stage section 4 and 108 in the second-stage section 4, they were fully filled with new catalysts (ratio is 1) and prepared for later use. At this time, the system returned to the initial startup operation state. Repeating this way, every four months, the reactor with deactivated catalyst was disconnected, the deactivated catalyst was discharged and processed, and prepared for later use. The valves were controlled to maintain the series operation of the remaining three reactors, realizing continuous and stable process production.

[0044] In the bisphenol A process with an annual production capacity of 460,000 tons in this example, the conversion rate of the first-stage reaction system was 99.5%, the selectivity was 96.8%, the conversion rate of the second-stage reaction system was 99.4%, and the selectivity was 97%.

[0045] (Example 2) When the system starts up, the raw material phenol, the raw material acetone and the circulating product of the first-stage reaction system are mixed. After being cooled to 68 °C by the first-stage cooler 109, they sequentially flow into the reactors 101 of the first-stage section 1, the reactor 102 of the first-stage section 2 and the reactor 103 of the first-stage section 3 in series, and a condensation reaction occurs. The catalyst filling ratio of the reactor 101 in the first-stage section 1 is 1 / 3, the catalyst filling ratio of the reactor 102 in the first-stage section 2 is 2 / 3, the catalyst filling of the reactor 103 in the first-stage section 3 is 1, and the catalyst filling ratio of the reactor 104 in the first-stage section 4 is 1. By valve control, the reactor 104 in the first-stage section 4 is temporarily disconnected from the reaction system. The unit bed pressure loss of the three reactors in series is 25 kPa / m, the outlet raw material temperature of the reactor in the first-stage section 3 is 76 °C, and the outlet products of the reactor 103 in the first-stage section 3 enter the first-stage circulation pump 115 and the inter-stage preheater 110 at a ratio of 2.1:1 respectively. The outlet temperature of the first-stage circulation pump is 73 °C. The reaction liquid heated to 87 °C by the inter-stage preheater 110 enters the flash evaporation tank 114, and is flash evaporated and dehydrated under a pressure of 5 kPaA. The vapor-phase outlet water and light by-products of the flash evaporation tank 114 enter the recovery system area after passing through the first-stage condenser 112 and the second-stage condenser 113. The liquid-phase outlet product of the flash evaporation tank 114 passes through the flash evaporation liquid pump and is then mixed with the replenished fresh acetone, and then sent to the second-stage cooler 111 to be cooled to 68 °C. After cooling, the reaction liquid sequentially flows into the reactors 105 of the second-stage section 1, the reactor 106 of the second-stage section 2 and the reactor 107 of the second-stage section 3 in series, and a condensation reaction occurs. The catalyst filling ratio of the reactor 105 in the second-stage section 1 is 1 / 3, the catalyst filling ratio of the reactor 106 in the second-stage section 2 is 2 / 3, the catalyst filling ratio of the reactor 107 in the second-stage section 3 is 1, and the catalyst filling ratio of the reactor 108 in the second-stage section 4 is 1. The pipeline connected to the reactor 108 in the second-stage section 4 is disconnected by valve control, and the reactor 108 in the second-stage section 4 is made to stand by alone. The unit bed pressure loss of the three reactors in series is 23 kPa / m, and the outlet raw material temperature of the reactor in the second-stage section 3 is 76 °C.The outlet product of the reactor 107 in section 3 of the second stage entered the inlet of the inter-stage preheater 110 and the inlet of the adsorption column 117 at a ratio of 0.9:1.

[0046] Five months after the operation of the system, the catalysts in the reactors 101 of section 1 of the first stage and 105 of section 1 of the second stage with a catalyst filling ratio of 1 / 3 lost their catalytic activity. The remaining service life of the catalysts in the reactors 102 of section 2 of the first stage and 106 of section 2 of the second stage with a catalyst filling ratio of 2 / 3 was 5 months. The remaining service life of the catalysts in the reactors 103 of section 3 of the first stage and 107 of section 3 of the second stage with a catalyst filling ratio of 1 was 10 months. The remaining service life of the catalysts in the reactors 104 of section 4 of the first stage and 108 of section 4 of the second stage was 15 months. At this time, through valve control, the reactors 101 of section 1 of the first stage and 105 of section 1 of the second stage in which the catalysts were deactivated were disconnected. The reactor 104 of section 4 of the first stage was started and directly connected to the reactor 102 of section 2 of the first stage and the reactor 103 of section 3 of the first stage. The raw material inlet valve of the reactor 102 of section 2 of the first stage and the product outlet valve of the reactor 104 of section 4 of the first stage were opened to control the raw material inflow and product outflow of the one-stage reactors. In the second-stage reaction system, the reactor 108 of section 4 of the second stage was started and connected in series with the reactor 106 of section 2 of the second stage and the reactor 107 of section 3 of the second stage. The inlet valve of the reactor 106 of section 2 of the second stage and the outlet valve of the reactor 108 of section 4 of the second stage were opened to control the raw material inflow and product outflow of the second-stage reaction system. After evaluating and discharging the deactivated catalysts in the disconnected reactors 101 of section 1 of the first stage and 105 of section 1 of the second stage for treatment, new catalysts (ratio is 1) were fully filled and prepared for later use.

[0047] Ten months after the operation of the system, reactors 102 in the first-stage section 2 and reactor 106 in the second-stage section 2 where the catalyst was deactivated due to valve control were disconnected. Reactor 101 in the first-stage section 1 was connected in series with reactor 103 in the first-stage section 3 and reactor 104 in the first-stage section 4. The raw material inlet valve of reactor 103 in the first-stage section 3 and the product outlet valve of reactor 101 in the first-stage section 1 were opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 105 in the second-stage section 1 was connected in series with reactor 106 in the second-stage section 3 and reactor 108 in the second-stage section 4. The raw material inlet valve of reactor 107 in the second-stage section 3 and the product outlet valve of reactor 105 in the second-stage section 1 were opened to control the raw material inflow and product outflow of the second-stage reaction system. The deactivated catalyst in reactors 102 in the first-stage section 2 and reactor 106 in the second-stage section 2 was evaluated, discharged and processed, and then filled with a new catalyst (ratio is 1) to be prepared for later use.

[0048] Fifteen months after the operation of the system, reactors 103 in the first-stage section 3 and reactor 107 in the second-stage section 3 where the catalyst was deactivated due to valve control were disconnected. Reactor 102 in the first-stage section 2 was connected in series with reactor 104 in the first-stage section 4 and reactor 101 in the first-stage section 1. The raw material inlet valve of reactor 104 in the first-stage section 4 and the product outlet valve of reactor 102 in the first-stage section 2 were opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 106 in the second-stage section 2 was connected in series with reactor 108 in the second-stage section 4 and reactor 105 in the second-stage section 1. The raw material inlet valve of reactor 108 in the second-stage section 4 and the product outlet valve of reactor 106 in the second-stage section 2 were opened to control the raw material inflow and product outflow of the second-stage reaction system. After discharging the deactivated catalyst in reactors 103 in the first-stage section 3 and reactor 107 in the second-stage section 3, they were filled with a new catalyst (ratio is 1) to be prepared for later use.

[0049] Twenty months after the system started operating, reactors 104 in the first-stage section 4 and 108 in the second-stage section 4, whose catalysts were deactivated by valve control, were disconnected. Reactor 103 in the first-stage section 3 was connected in series with reactor 101 in the first-stage section 1 and reactor 102 in the first-stage section 2. The raw material inlet valve of reactor 101 in the first-stage section 1 and the product outlet valve of reactor 103 in the first-stage section 3 were opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 107 in the second-stage section 3 was connected in series with reactor 105 in the second-stage section 1 and reactor 106 in the second-stage section 2. The raw material inlet valve of reactor 105 in the second-stage section 1 and the product outlet valve of reactor 107 in the second-stage section 3 were opened to control the raw material inflow and product outflow of the second-stage reaction system. The deactivated catalysts in reactors 104 in the first-stage section 4 and 108 in the second-stage section 4 were discharged, and the reactors were fully filled with new catalysts (ratio is 1) and prepared for later use. At this time, it returned to the initial startup operation state again. Repeating in this way, every five months, the reactors with deactivated catalysts were disconnected, the deactivated catalysts inside were discharged and processed, and prepared for later use. The valves were controlled to maintain the series operation of the remaining three reactors, realizing continuous and stable process production.

[0050] In the bisphenol A process with an annual production capacity of 470,000 tons in this example, the conversion rate of the first-stage reaction system was 99.6%, the selectivity was 97%, the conversion rate of the second-stage reaction system was 99.5%, and the selectivity was 97.4%.

[0051] (Example 3) When the system starts up, the raw material phenol, the raw material acetone, and the circulating product of the first-stage reaction system are mixed. After being cooled to 70 °C by the first-stage cooler 109, they sequentially flow into the reactors 101 of the first-stage section 1, the reactor 102 of the first-stage section 2, and the reactor 103 of the first-stage section 3 in series, and a condensation reaction occurs. The catalyst filling ratio of the reactor 101 in the first-stage section 1 is 1 / 3, the catalyst filling ratio of the reactor 102 in the first-stage section 2 is 2 / 3, the catalyst filling of the reactor 103 in the first-stage section 3 is 1, and the catalyst filling ratio of the reactor 104 in the first-stage section 4 is 1. By valve control, the reactor 104 in the first-stage section 4 is temporarily disconnected from the reaction system. The unit bed pressure loss of the three reactors in series is 30 kPa / m, the outlet raw material temperature of the reactor in the first-stage section 3 is 76 °C, and the outlet products of the reactor 103 in the first-stage section 3 enter the first-stage circulation pump 115 and the inter-stage preheater 110 at a ratio of 2.2:1 respectively. The outlet temperature of the first-stage circulation pump is 75 °C, and the reaction liquid heated to 90 °C by the inter-stage preheater 110 enters the flash evaporation tank 114, where it undergoes flash evaporation and dehydration under a pressure of 7 kPaA. The vapor-phase outlet water and light by-products of the flash evaporation tank 114 enter the recovery system area after passing through the first-stage condenser 112 and the second-stage condenser 113. The liquid-phase outlet product of the flash evaporation tank 114 passes through the flash evaporation liquid pump and is then mixed with the replenished fresh acetone, and then sent to the second-stage cooler 111 to be cooled to 70 °C. After cooling, the reaction liquid sequentially flows into the reactors 105 of the second-stage section 1, the reactor 106 of the second-stage section 2, and the reactor 107 of the second-stage section 3 in series, and a condensation reaction occurs. The catalyst filling ratio of the reactor 105 in the second-stage section 1 is 1 / 3, the catalyst filling ratio of the reactor 106 in the second-stage section 2 is 2 / 3, the catalyst filling ratio of the reactor 107 in the second-stage section 3 is 1, and the catalyst filling ratio of the reactor 108 in the second-stage section 4 is 1. The pipeline connected to the reactor 108 in the second-stage section 4 is disconnected by valve control, and the reactor 108 in the second-stage section 4 is put on standby alone. The unit bed pressure loss of the three reactors in series is 28 kPa / m, and the outlet raw material temperature of the reactor in the second-stage section 3 is 80 °C.The outlet product of the reactor 107 in section 3 of the second stage entered the inlet of the inter-stage preheater 110 and the inlet of the adsorption column 117 at a ratio of 1:1.

[0052] Six months after the operation of the system, the catalysts in the reactors 101 of section 1 of the first stage and 105 of section 1 of the second stage with a catalyst filling ratio of 1 / 3 lost their catalytic activity. The remaining life of the catalysts in the reactors 102 of section 2 of the first stage and 106 of section 2 of the second stage with a catalyst filling ratio of 2 / 3 was 6 months. The remaining life of the catalysts in the reactors 103 of section 3 of the first stage and 107 of section 3 of the second stage with a catalyst filling ratio of 1 was 12 months. The remaining life of the catalysts in the reactors 104 of section 4 of the first stage and 108 of section 4 of the second stage was 18 months. At this time, through valve control, the reactors 101 of section 1 of the first stage and 105 of section 1 of the second stage where the catalysts were deactivated were disconnected. The reactor 104 of section 4 of the first stage was started and directly connected to the reactor 102 of section 2 of the first stage and the reactor 103 of section 3 of the first stage. The raw material inlet valve of the reactor 102 of section 2 of the first stage and the product outlet valve of the reactor 104 of section 4 of the first stage were opened to control the raw material inflow and product outflow of the first-stage reaction system. In the second-stage reaction system, the reactor 108 of section 4 of the second stage was started and connected in series with the reactor 106 of section 2 of the second stage and the reactor 107 of section 3 of the second stage. The inlet valve of the reactor 106 of section 2 of the second stage and the outlet valve of the reactor 108 of section 4 of the second stage were opened to control the raw material inflow and product outflow of the second-stage reaction system. After evaluating and discharging the deactivated catalysts in the disconnected reactors 101 of section 1 of the first stage and 105 of section 1 of the second stage and processing them, new catalysts (ratio 1) were fully filled and prepared for later use.

[0053] Twelve months after the operation of the system, reactors 102 in the first-stage section 2 and reactor 106 in the second-stage section 2 where the catalyst has been deactivated are disconnected by valve control. Reactor 101 in the first-stage section 1 is connected in series with reactor 103 in the first-stage section 3 and reactor 104 in the first-stage section 4. The raw material inlet valve of reactor 103 in the first-stage section 3 and the product outlet valve of reactor 101 in the first-stage section 1 are opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 105 in the second-stage section 1 is connected in series with reactor 107 in the second-stage section 3 and reactor 108 in the second-stage section 4. The raw material inlet valve of reactor 107 in the second-stage section 3 and the product outlet valve of reactor 105 in the second-stage section 1 are opened to control the raw material inflow and product outflow of the second-stage reaction system. After discharging the deactivated catalyst in reactors 102 in the first-stage section 2 and reactor 106 in the second-stage section 2, new catalyst (ratio is 1) is fully filled and prepared for later use.

[0054] Eighteen months after the operation of the system, reactors 103 in the first-stage section 3 and reactor 107 in the second-stage section 3 where the catalyst has been deactivated are disconnected by valve control. Reactor 102 in the first-stage section 2 is connected in series with reactor 104 in the first-stage section 4 and reactor 101 in the first-stage section 1. The raw material inlet valve of reactor 104 in the first-stage section 4 and the product outlet valve of reactor 102 in the first-stage section 2 are opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 106 in the second-stage section 2 is connected in series with reactor 108 in the second-stage section 4 and reactor 105 in the second-stage section 1. The raw material inlet valve of reactor 108 in the second-stage section 4 and the product outlet valve of reactor 106 in the second-stage section 2 are opened to control the raw material inflow and product outflow of the second-stage reaction system. After discharging the deactivated catalyst in reactors 103 in the first-stage section 3 and reactor 107 in the second-stage section 3, new catalyst (ratio is 1) is fully filled and prepared for later use.

[0055] Twenty-four months after the system starts operation, reactors 104 in the first-stage section 4 and reactor 108 in the second-stage section 4 in which the catalyst is deactivated due to valve control are disconnected. Reactor 103 in the first-stage section 3 is connected in series with reactor 101 in the first-stage section 1 and reactor 102 in the first-stage section 2. The raw material inlet valve of reactor 101 in the first-stage section 1 and the product outlet valve of reactor 103 in the first-stage section 3 are opened to control the raw material inflow and product outflow of the first-stage reaction system. Reactor 107 in the second-stage section 3 is connected in series with reactor 105 in the second-stage section 1 and reactor 106 in the second-stage section 2. The raw material inlet valve of reactor 105 in the second-stage section 1 and the product outlet valve of reactor 107 in the second-stage section 3 are opened to control the raw material inflow and product outflow of the second-stage reaction system. The deactivated catalyst in reactors 104 in the first-stage section 4 and reactor 108 in the second-stage section 4 is discharged, and the reactors are filled with new catalyst (ratio is 1) and prepared for later use. At this time, it returns to the initial startup operation state again. Repeat this way, disconnect the reactor in which the catalyst is deactivated every six months, discharge and process the deactivated catalyst in it, prepare it for later use, and control the valves to maintain the series operation of the remaining three reactors to achieve continuous and stable process production.

[0056] In the bisphenol A process with an annual production capacity of 480,000 tons in this embodiment, the conversion rate of the first-stage reaction system is 99.8%, the selectivity is 97.5%, the conversion rate of the second-stage reaction system is 99.6%, and the selectivity is 98%.

[0057] The advantageous technical effects of the present invention are as follows: By using the series operation method of reactors, a larger space velocity can be provided, the conversion rate and selectivity of the reaction can be improved, the production scale of bisphenol A can be expanded. The catalyst evaluation and analysis during the trial operation period of the system are facilitated by the catalyst filling ratio scheme, the catalyst loss is reduced, and the economic benefits of the process are improved.

[0058] The devices not particularly pointed out in the present invention are conventional devices and can be realized using methods and devices known to those skilled in the art. Although the present invention has been described with reference to specific embodiments and figures, the present invention is not intended to be limited to the specific forms described herein. Rather, the scope of the present invention is limited only by the appended claims. Note that individual features may be included in different claims, but these features may be advantageously combined, and inclusion in different claims does not indicate that the combination of features is impossible and / or advantageous. The terms "first" and "second" do not exclude the plural form.

Explanation of Signs

[0059] 101 Reactor of the first-stage section 1 102 Reactor of the first-stage section 2 103 Reactor of the first-stage section 3 104 Reactor of the first-stage section 4 105 Reactor of the second-stage section 1 106 Reactor of the second-stage section 2 107 Reactor of the second-stage section 3 108 Reactor of the second-stage section 4 109 First-stage cooler 110 Inter-stage preheater 111 Second-stage cooler 112 First-stage condenser 113 Second-stage condenser 114 Flash evaporator 115 First-stage circulation pump 116 Flash evaporation liquid pump 117 Adsorption column

Claims

1. A method for producing bisphenol A, comprising a two-stage reaction system and an interstage dehydration system, each stage of the reaction system including a cooler and four reactors in four stages, a bisphenol A synthetic resin catalyst is filled into the reactors before the start-up operation of the system, the catalyst filling ratio is 1 / 3 for the reactor in section 1, 2 / 3 for the reactor in section 2, and 1 for the reactors in section 3 and section 4, the reactors in section 1, section 2, and section 3 are operated in series by valve control, the reaction raw material is charged from the inlet of the reactor in section 1, and the product is fed from the inlet of the reactor in section 2, and the product is fed from the inlet of the reactor in section 3. The catalyst is extracted from the outlet of the reactor in section 3, and any three reactors are controlled to realize serial operation, and the other reactors can be stopped independently without affecting the flow of the entire process. The catalyst loading ratio in the reactors before the start-up operation of the system is 1 / 3 for the reactor in section 1, 2 / 3 for the reactor in section 2, 1 for the reactor in section 3, and 1 for the reactor in section 4, respectively. After the start-up operation, the reactor in which the catalyst has been deactivated is isolated by valve control every 1 / 3 of the catalyst use cycle, and the serial operation of the remaining three reactors is controlled to realize continuous production. The reactor switching method during the operation of the system is as follows: 1) After cooling, acetone, excess phenol and the first-stage reaction liquid circulating stream are sent to the first-stage reaction system to carry out a reaction to produce bisphenol A, and a mixture of bisphenol A, unreacted phenol and by-products is obtained; the raw material discharged from the first-stage reaction system is partially returned to the first-stage reaction system as a circulating stream so as to lower the temperature of the raw material discharged from the first-stage reaction system to 76° C. or less; the discharged raw material and the circulating reaction liquid of the second-stage reaction system enter the interstage dehydration system, where they are preheated and then subjected to vacuum flash evaporation and dehydration; the dehydrated raw material is sent to the second-stage reaction system, where it is cooled together with fresh acetone supplied at the feed point of the second-stage reaction system, and then reacted in the second-stage reaction system to obtain a bisphenol A reaction liquid; the reaction liquid is divided into two streams, one of which is recycled to the interstage dehydration system, and the flow rate ratio is adjusted so as to lower the raw material temperature at the outlet of the second-stage reactor to 80° C. or less; and the other stream is withdrawn and sent to an adsorption column; 2) When the catalyst in the reactor of section 1 loses catalytic activity, the life of the catalyst in the reactor of section 2 with a catalyst loading ratio of 2 / 3 becomes 1 / 3, and the life of the catalyst in the reactor of section 3 with a catalyst loading ratio of 1 becomes 2 / 3. At this time, the reactor of section 1 with the deactivated catalyst is isolated by valve control, and the reactor of section 4 and the reactor of section 2 and section 3 are switched to serial operation, and the reaction raw material is controlled to enter from the reactor of section 2 of the catalyst and the reaction product is controlled to be extracted from the reactor of section 4. The deactivated catalyst in the isolated reactor of section 1 is discharged and processed, and the reactor is filled with new catalyst with a loading ratio of 1 and prepared for later use. 3) when the catalyst in the reactor of section 2 loses catalytic activity, the reactor of section 2 in which the catalyst has been deactivated is isolated by valve control, and the reactor of section 1 and the reactor of section 3 and section 4 are switched to serial operation, the deactivated catalyst in the isolated reactor of section 2 is removed and treated, and new catalyst is filled up and prepared for later use, and the raw material is controlled so that it enters through the inlet of the reactor of section 3 and is withdrawn from the outlet of the reactor of section 1; 4) When the catalyst in the reactor in section 3 loses catalytic activity, the reactor in section 3 in which the catalyst has been deactivated is isolated by valve control, and the reactor in section 2 and the reactor in section 1, section 4 are switched to serial operation, the deactivated catalyst in the isolated reactor in section 3 is removed and treated, and new catalyst is filled up and prepared for later use, and the raw material is controlled so as to enter the reactor in section 4 through the inlet and to be withdrawn from the reactor in section 2 through the outlet; 5) When the catalyst in the reactor in section 4 loses catalytic activity, the reactor in section 4 with the deactivated catalyst is isolated by valve control, and the reactor in section 3 and the reactors in sections 1 and 2 are switched to serial operation, the deactivated catalyst in the isolated reactor in section 4 is discharged and treated, and new catalyst is filled and prepared for later use, and the raw material is controlled to enter the inlet of the reactor in section 1 and withdrawn from the outlet of the reactor in section 3, and the operation mode of the system returns to the starting state. A method for producing bisphenol A.

2. 2. The method for producing bisphenol A according to claim 1, wherein the catalyst is a bisphenol A synthetic resin catalyst and contains a mercapto-modified strongly acidic cation exchange resin.

3. 2. An apparatus for carrying out the method for producing bisphenol A according to claim 1, wherein each reactor is provided with a raw material inlet and a product outlet, the inlet of each reactor in the first-stage reaction system is connected to the outlet of the first-stage cooler, the outlet of each reactor is connected to the inlet of the first-stage circulation heat removal pump and the inlet of the interstage preheater, respectively, the outlet of the reactor in the first-stage section 1 is connected to the inlet of the reactor in the first-stage section 2, the outlet of the reactor in the first-stage section 2 is connected to the inlet of the reactor in the first-stage section 3, and the outlet of the reactor in the first-stage section 3 is connected to the inlet of the first-stage section 4. the outlet of the first stage section 4 reactor is connected to the inlet of the first stage section 1 reactor; the outlet of the first stage circulation pump is connected to the inlet of the first stage cooler; the outlet of the interstage preheater is connected to the inlet of a flash evaporator; the vapor phase outlet of the flash evaporator is connected to the inlet of a first stage condenser; the outlet of the first stage condenser is connected to the inlet of a recovery system and a second stage condenser, respectively; the outlet of the second stage condenser is connected to the recovery system and a vacuum unit, respectively; a first phase outlet connected to the inlet of a flash evaporative liquid pump, an outlet of the flash evaporative liquid pump connected to the inlet of a second stage cooler, an acetone feed pipe connected to the inlet of the first stage cooler and the inlet of the second stage cooler, a phenol feed pipe connected to the inlet of the first stage cooler, an inlet of each reactor in the second stage reaction system connected to the outlet of the second stage cooler, an outlet of each reactor connected to the inlet of the interstage preheater and the inlet of the adsorption column, respectively, and an outlet of the reactor in the second stage section 1 connected to the inlet of the reactor in the second stage section 2. an outlet of the reactor in the second stage section 2 is connected to the inlet of the reactor in the second stage section 3, an outlet of the reactor in the second stage section 3 is connected to the inlet of the reactor in the second stage section 4, and an outlet of the reactor in the second stage section 4 is connected to the inlet of the reactor in the second stage section 1; the pipelines in each stage of the reaction system are controlled to open and close by valves, any three reactors can be connected in series, and the outlet of the adsorption column is connected to the inlet pipeline of a concentrated bisphenol A system.

4. The apparatus for carrying out the process for producing bisphenol A according to claim 3, characterized in that the outlet temperature of the first-stage cooler on the cooling side is 65 to 70°C, the unit bed layer pressure loss of the first-stage series reactor is 15 to 30 kPa / m, the outlet temperature of the first-stage series reactor is less than 76°C, and the outlet temperature of the first-stage circulation pump is 72 to 76°C.

5. The apparatus for carrying out the process for producing bisphenol A according to claim 3, characterized in that the outlet temperature of the temperature-reducing side of the second-stage cooler is 65 to 70°C, the unit bed layer pressure loss of the second-stage series reactor is 7 to 28 kPa / m, and the outlet temperature of the second-stage series reactor is 72 to 80°C.

6. 4. An apparatus for carrying out the method for producing bisphenol A according to claim 3, characterized in that the outlet temperature on the temperature-raising side of the interstage preheater is 85 to 90° C., and the pressure of the dehydration flash evaporator is 3 to 7 kPaA.

7. The apparatus for carrying out the process for producing bisphenol A according to claim 3, characterized in that the flow rate ratio of the second-stage reactor outlet feed stream entering the interstage dehydration system to the second-stage reactor outlet feed stream sent to the adsorption column is 0.8:1 to 1:1.

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