Method, system, and apparatus for control of bromine recovery in an oxidation off-gas vent scrubber

Abstract

A control method for recovering bromine in an oxidation tail gas vent scrubber tower, comprising the following steps: detecting wastewater from the bottom of the oxidation tail gas vent scrubber tower into the separation tower; controlling the wastewater discharged from the bottom of the scrubber to enter the bromine recovery unit separator for evaporation and concentration; controlling the steam flashed out from the top of the separator to enter the steam compressor for pressurization, wherein the pressurized steam is used to heat the circulating liquid at the bottom of the separator, and the condensate is discharged to the condensate system for steam circulation process; concentrated liquid is generated at the bottom of the separator, and the concentrated liquid at the bottom of the separator is transported by a circulating pump to be divided into two streams, one stream of concentrated liquid is circulated and evaporated, and one stream of concentrated liquid is controlled to be input into a filtering unit to separate and filter out sodium carbonate crystals; the filtrate mainly composed of sodium bromide and sodium acetate is controlled to enter a membrane separation unit to perform membrane separation; hydrogen bromide acid, hydrogen bromide and acetic acid, and acetic acid obtained through membrane separation in the membrane separation unit are controlled to be re-input into a brominating agent device of an oxidation unit for recycling.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wastewater treatment, in particular to a control method, system and device for bromine recovery in an oxidation tail gas vent scrubber. BACKGROUND

[0002] Purified terephthalic acid (PTA) is a direct upstream raw material for polyester. China is the world's largest producer and consumer of PTA. Generally speaking, the upstream raw materials in the PTA industry chain mainly include PX produced and processed from acetic acid and crude oil, the middle stream is mainly PTA, and the downstream is mainly used for producing PET fibers, among which, the civil polyester filament and polyester staple fiber are mainly applied in the textile and garment industry, and the polyester industrial yarn is mainly applied in the automobile field. At present, PTA is mainly produced by p-xylene air oxidation method. In this method, the raw material p-xylene is dissolved in an acetic acid monohydrate solvent containing a catalyst, such as cobalt acetate, manganese acetate and hydrogen bromide, and air or oxygen-rich air is introduced for oxidation to generate solid product terephthalic acid. The main components of the tail gas generated in the production process are nitrogen, carbon dioxide, carbon monoxide and brominated organic compounds. After washing and debromination in the scrubber, the main components of the scrubbing wastewater are bicarbonate ions, carbonate ions and bromide ions. Since hydrogen bromide is consumed in the reaction stage, it needs to be continuously supplemented. The methods given at the present stage all need to add other substances for separation; the present application provides a simple, practical and effective method, which only consumes a small amount of steam and a part of electric energy to recover high-value bromine, sodium carbonate and sodium hydroxide from the treated wastewater, and all of them can be recycled in the PTA device, greatly improving the utilization rate of catalysts and additives. SUMMARY

[0003] One of the purposes of the present application is to provide a control method, system and device for bromine recovery in an oxidation tail gas vent scrubber, which can recover bromine from the wastewater discharged from the bottom of the oxidation tail gas vent scrubber and then re-enter the bromination agent device for recycling.

[0004] Another purpose of the present application is to provide a control method, system and device for bromine recovery in an oxidation tail gas vent scrubber, which can not only control the discharge concentration of each unit of the MVR unit, the filtration unit and the membrane separation unit through computer internal program calculation, but also feedback adjust the discharge concentration of each unit of the three units according to the final discharge concentration of the bromine recovery system.

[0005] In order to achieve the above at least one inventive purpose of the present application, the present application provides a control method for bromine recovery in an oxidation tail gas vent scrubber, which comprises the following steps:

[0006] detecting the wastewater from the bottom of the vent gas scrubber of the oxidation tail gas venting into the separator;

[0007] controlling the wastewater from the bottom of the scrubber to enter the separator of the bromine recovery unit for evaporation concentration;

[0008] controlling the steam from the top of the separator to enter the steam compressor for pressure increase, wherein the pressurized steam is used to heat the circulating liquid at the bottom of the separator, and the condensate is discharged to the condensate system for steam circulation process;

[0009] generating concentrated liquid at the bottom of the separator, and controlling the concentrated liquid at the bottom of the separator to be transported by a circulating pump into two streams, one of which is evaporated by circulation, and the other of which is controlled to be input into the filtration unit to separate and filter out sodium carbonate crystals;

[0010] controlling the filtrate mainly composed of sodium bromide and sodium acetate to enter the membrane separation unit to perform membrane separation;

[0011] and

[0012] the hydrogen bromide and acetic acid obtained by membrane separation in the membrane separation unit are controlled to be re-input into the brominating agent device of the oxidation unit for recycling;

[0013] wherein a smart network calculation model is established to perform real-time online analysis of the discharge concentration, and when it is necessary to improve the discharge concentration of the concentration device, a signal for increasing the concentration is sent to the MVR unit, the filtration unit and the membrane separation unit, so as to increase the bromide ion concentration.

[0014] In some embodiments, the control method for bromine recovery in the vent gas scrubber of the oxidation tail gas further comprises the step of increasing the bromide ion concentration of the MVR unit: adjusting the frequency of the compressor and adjusting the amount of supplementary steam.

[0015] In some embodiments, the control method for bromine recovery in the vent gas scrubber of the oxidation tail gas further comprises the step of increasing the bromide ion concentration of the filtration unit: increasing the rotation speed of the centrifugal filter, increasing the residence time of the filtrate in the filter, and reducing the temperature of the filtrate.

[0016] In some embodiments, the control method for bromine recovery in the vent gas scrubber of the oxidation tail gas further comprises the step of increasing the bromide ion concentration of the membrane separation unit: increasing the voltage of the membrane separator, and increasing the current of the membrane separator.

[0017] In some embodiments, the control method for bromine recovery in the vent gas scrubber of the oxidation tail gas further comprises the step of: according to the online feed concentration within a preset fluctuation range, controlling the heat entering the evaporator to affect the evaporation amount, so as to ensure that the CO3 2-The ion concentration, Na+ ion concentration, and bromine ion concentration fluctuate within a preset range. Factors affecting the evaporation amount include the top pressure and temperature of the separator and the bottom pressure and temperature of the separator. The top and bottom temperatures of the separator are adjusted by adjusting the amount of steam and the frequency of the compressor. The bottom and top pressures of the separator are adjusted by adjusting the speed of the compressor, thereby affecting the evaporation amount inside the separator, to ensure that the material liquid exits the MVR unit CO3 2- The ion concentration, Na+ ion concentration, and bromine ion concentration fluctuate within a preset range.

[0018] In some embodiments, the control method for bromine recovery in the oxidation tail gas vent scrubbing tower further comprises the step of: setting a liquid control valve on the feed line to control the small amplitude fluctuation of the separator liquid level around any set value between 30% and 85%.

[0019] In some embodiments, the control method for bromine recovery in the oxidation tail gas vent scrubbing tower further comprises the step of: adjusting the filtrate feed amount of the filter unit according to the pressure difference before and after the filter unit feed line.

[0020] According to another aspect of the present application, a control system for bromine recovery in an oxidation tail gas vent scrubbing tower is also provided, which comprises a plurality of hardware function modules, each of which is used to correspondingly perform the steps in the control method for bromine recovery in the oxidation tail gas vent scrubbing tower.

[0021] According to another aspect of the present application, a PTA device oxidation unit is also provided, which is connected with the control system for bromine recovery in the oxidation tail gas vent scrubbing tower, which recovers bromine from the wastewater discharged from the bottom of the oxidation tail gas vent scrubbing tower, and the recovered bromine is recycled and reused in the brominating agent tank of the PTA device oxidation unit.

[0022] According to another aspect of the present application, a control device for bromine recovery in an oxidation tail gas vent scrubbing tower is also provided, which comprises:

[0023] a memory for storing a software application,

[0024] a processor for executing the software application, each program of the software application corresponding to performing the steps in the control method for bromine recovery in the oxidation tail gas vent scrubbing tower. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a step flowchart of a control method for bromine recovery in an oxidation tail gas vent scrubbing tower according to an embodiment of the present application.

[0026] Figure 2is a schematic diagram of a control system for bromine recovery in an oxidation off-gas vent scrubber according to an embodiment of the present application.

[0027] Figure 3 is a schematic diagram of the control system for bromine recovery in the oxidation off-gas vent scrubber according to the above embodiment of the present application, showing the re-use of the recovered bromine from the wastewater discharged from the bottom of the oxidation off-gas vent scrubber into the brominating agent device. DETAILED DESCRIPTION

[0028] The following description is presented to enable any person skilled in the art to practice the present application as claimed. The preferred embodiments disclosed herein are only examples of the present application and alternative embodiments will be apparent to those skilled in the art upon reading the present disclosure. The detailed description includes specific details for the purpose of providing a thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced without these specific details. In some instances, well-known structures and functions have been not described in detail in order to avoid obscuring the concept of the present application.

[0029] It is to be understood that the term "a" or "an" shall not be construed as limiting the number of items to a single item, but rather "one or more". That is, a number of items can be present. Where the term "at least one" is used, this is to be understood to mean "one or more" and thus the number of items can be more than one.

[0030] The present application is an application related to a computer program. As Figure 1 is a flow chart of a control method for bromine recovery in an oxidation off-gas vent scrubber according to the present application, which illustrates the solution to the problems presented by the present application based on the computer program processing flow, and the solution is to control or process the external or internal objects of the computer by executing the computer program prepared according to the above flow by the computer. Through the control method for bromine recovery in the oxidation off-gas vent scrubber according to the present application, the discharge concentrations of the MVR unit, the filtration unit, and the membrane separation unit are controlled by the computer internal program calculation, and the discharge concentrations of the three units can also be adjusted according to the final discharge concentration of the bromine recovery system. The control method for bromine recovery in the oxidation off-gas vent scrubber according to the present application can control the entire process of bromine recovery by using the computer system, so that the recovered bromine from the wastewater discharged from the bottom of the oxidation off-gas vent scrubber can be re-used in the brominating agent device.

[0031] Specifically, the control method for bromine recovery in the oxidation off-gas vent scrubber includes the following steps:

[0032] detecting the wastewater from the bottom of the oxidation off-gas vent scrubber entering the separator;

[0033] controlling the wastewater discharged from the bottom of the scrubber to enter the separator of the bromine recovery unit for evaporation and concentration;

[0034] The vapor flashed out from the top of the separator is controlled to enter a vapor compressor to be pressurized, and the pressurized vapor is used to heat the circulating liquid at the bottom of the separator, and the condensate is discharged to a condensate system for a steam circulation process.

[0035] The concentrated liquid at the bottom of the separator is controlled to be transported by a circulating pump in two streams, one of which is evaporated by circulation, and the other is controlled to be input into a filtration unit to separate and filter out sodium carbonate crystals.

[0036] The filtrate mainly composed of sodium bromide and sodium acetate is controlled to enter a membrane separation unit to perform membrane separation.

[0037] High-purity HBr (hydrobromic acid / hydrogen bromide) and HAc (acetic acid / ethanoic acid) obtained by membrane separation in the membrane separation unit are controlled to be re-input into the brominating agent device of the oxidation unit for recycling.

[0038] More specifically, the control method for recovering bromine in the oxidation tail gas venting scrubbing tower includes a control step of separating the liquid level: a liquid control valve is arranged in the feed line, and the liquid level of the separator is controlled to fluctuate around an arbitrary set value within a range of 30% to 85%, preferably within a range of 35% to 85%. It is understood by those skilled in the art that if the liquid level is too low, the circulating pump may be empty, and if the liquid level is too high, the evaporator outlet may even be full, causing the liquid in the separator to splash and spray. The liquid level of a general chemical container is controlled in the middle range to facilitate observation and safe production. Therefore, in order to ensure the safe production requirements of the separator, the range is set to be between 30% and 85%, and preferably between 35% and 85%.

[0039] Further, the control method for recovering bromine in the oxidation tail gas venting scrubbing tower further includes the following steps:

[0040] The fluctuation range of the online feed concentration is detected and obtained, the heat entering the evaporator is controlled, and then the evaporation amount is affected to ensure that the bromide ion concentration of the feed liquid out of the MVR (mechanical vapor recompression) unit fluctuates within a preset range.

[0041] That is, the factors affecting the evaporation amount include the top pressure and temperature of the separator and the bottom pressure and temperature of the separator; the top and bottom temperatures of the separator are adjusted by supplementing the amount of steam and the frequency of the compressor, and the bottom and top pressures of the separator are adjusted by the speed of the compressor, thereby affecting the evaporation amount in the separator to ensure that the bromide ion concentration of the feed liquid out of the MVR unit fluctuates within a preset range.

[0042] Those skilled in the art can understand that the CO3 2- ion concentration, Na +The ion concentration can also be controlled. That is, in specific embodiments, the heat entering the evaporator is controlled to affect the evaporation rate to ensure that the concentration of the Na+ion in the feed liquid exiting the MVR unit is within a predetermined range according to the concentration of the on-line feed within a certain fluctuation range. 2- The ion concentration fluctuates within a certain range; factors affecting the evaporation rate include the top pressure and temperature of the separator and the bottom pressure and temperature of the separator; the top and bottom temperatures of the separator are adjusted by adjusting the amount of steam supplement and the compressor frequency, the bottom and top pressures of the separator are adjusted by adjusting the compressor speed, thereby affecting the evaporation rate inside the separator, to ensure that the concentration of the Na+ion in the feed liquid exiting the MVR unit is within a predetermined range. 2- The ion concentration fluctuates within a certain range; factors affecting the evaporation rate include the top pressure and temperature of the separator and the bottom pressure and temperature of the separator; the top and bottom temperatures of the separator are adjusted by adjusting the amount of steam supplement and the compressor frequency, the bottom and top pressures of the separator are adjusted by adjusting the compressor speed, thereby affecting the evaporation rate inside the separator, to ensure that the concentration of the Na+ion in the feed liquid exiting the MVR unit is within a predetermined range. + The ion concentration fluctuates within a certain range; factors affecting the evaporation rate include the top pressure and temperature of the separator and the bottom pressure and temperature of the separator; the top and bottom temperatures of the separator are adjusted by adjusting the amount of steam supplement and the compressor frequency, the bottom and top pressures of the separator are adjusted by adjusting the compressor speed, thereby affecting the evaporation rate inside the separator, to ensure that the concentration of the Na+ion in the feed liquid exiting the MVR unit is within a predetermined range. + The ion concentration fluctuates within a certain range.

[0043] More specifically, in preferred embodiments, the control method for recovering bromine in the oxidation tail gas vent scrubber further includes the following steps for increasing the concentration of bromide ions in the MVR unit: adjusting the compressor frequency and adjusting the amount of steam supplement. More specifically, the compressor frequency is increased and the amount of steam supplement is increased. That is, by increasing the compressor frequency, the top pressure and the bottom pressure are reduced, thereby controlling the top pressure of the separator, the bottom temperature of the separator is reduced, thereby controlling the bottom temperature of the separator; by increasing the amount of steam supplement, the top temperature of the separator is increased, the bottom pressure of the separator is reduced, and the temperature of the separator is increased; thereby controlling the concentration of bromide ions in the feed liquid exiting the MVR unit within a predetermined range.

[0044] Further, the control method for recovering bromine in the oxidation tail gas vent scrubber further includes the following steps for increasing the concentration of bromide ions in the filtration unit: increasing the speed of the centrifugal filter, increasing the residence time of the filtrate in the filter; and reducing the temperature of the filtrate. In preferred embodiments, the filtration unit adjusts the speed of the filter, the residence time of the filtrate in the filtration unit, and the temperature of the filtrate according to the fluctuation of the concentration of the feed liquid.

[0045] Further, the control method of bromine recovery in the vent gas scrubber further comprises the step of adjusting the filtrate feed amount of the filtration unit according to the pressure difference before and after the filtration unit feed line. That is, the filtration unit feed and discharge line pressure difference is controlled, and when the pressure difference is too large, the feed amount is reduced, thereby controlling the filtration unit feed amount. That is, when the feed amount of the filtration unit is reduced, in order to maintain the MVR unit separator level at a set value, the MVR unit feed amount is also reduced, and then the steam compressor frequency and the amount of supplemental steam are also reduced accordingly.

[0046] Further, the control method of bromine recovery in the vent gas scrubber further comprises the following steps of increasing the membrane separation machine voltage and increasing the membrane separation machine current to increase the bromine ion concentration of the membrane separation unit.

[0047] Further, the control method of bromine recovery in the vent gas scrubber further comprises the following steps of increasing the membrane separation machine voltage and increasing the membrane separation machine current to increase the bromine ion concentration of the membrane separation unit.

[0048] The intelligent network calculation model is established, online analysis is performed according to the discharge concentration, signals for increasing the concentration of the MVR unit, the filtration unit and the membrane separation unit are respectively given, and the MVR unit, the filtration unit and the membrane separation unit are controlled and the bromine ion concentration is increased. In the preferred embodiment, when the bromine recovery control system in the vent gas scrubber is normally operated, an advanced control program of the recovery system is developed by means of big data and artificial intelligence, supplemented by model predictive control (MPC), industrial mechanism model and other technologies. The whole control program takes the separator feed flow, the compressor frequency, the supplemental steam amount, the filter speed, the voltage and current of the membrane separation machine as the operation variables, takes the liquid level of the separator, the pressure and temperature at the top of the separator, the pressure and temperature at the bottom of the separator, the concentration of the concentrated liquid after the membrane separation, the concentration of the recovered liquid after the filtration unit and the final concentration of the recovered liquid as the controlled variables, obtains the mapping relationship between the two, then performs AI data mining, and the algorithm model can be selected from full connection neural network (FCN), extreme gradient boosting decision tree (Xgboost), random forest (Random forest), support vector machine (SVM), linear regression (LR) and the like; thereby the advanced control program of the recovery system is established.

[0049] Those skilled in the art can understand that the method of the present application can be realized by hardware, software, or a combination of software and hardware. Therefore, the present application can take the form of an all-hardware embodiment, an all-software embodiment, or an embodiment combining software and hardware. The present application can be realized in a centralized manner in at least one computer system, or in a decentralized manner by different parts distributed in several interconnected computer systems. Any computer system or other device capable of implementing the method is applicable. The commonly used combination of software and hardware can be a general-purpose computer system installed with a computer program, which controls the computer system by installing and executing the program, so that the computer system operates according to the method.

[0050] The present application can be embedded in a computer program product, which includes all the features described herein to enable the method described herein to be implemented. The computer program product is contained in one or more computer readable storage media, which has computer readable program code contained therein. According to another aspect of the present application, a computer readable storage medium is also provided, which stores a computer program that can perform the steps of the method of the present application when executed by a processor. The computer storage medium is a medium for storing some discrete physical quantity in a computer memory. The computer storage medium includes, but is not limited to, semiconductors, magnetic disk storage, magnetic cores, magnetic drums, magnetic tapes, laser discs, etc. Those skilled in the art can understand that the computer storage medium is not limited to the foregoing examples, and the foregoing examples are merely examples and are not limited to the present application.

[0051] Corresponding to the embodiments of the method of the present application, according to another aspect of the present application, as shown in Figure 2 The control system for recovering bromine in the vent scrubber of the oxidation tail gas is an application of the control method for recovering bromine in the vent scrubber of the oxidation tail gas in the computer program improvement of the present application.

[0052] Specifically, the control system for recovering bromine in the vent scrubber of the oxidation tail gas includes a separator, a steam compressor, a filtration unit, and a membrane separation unit.

[0053] More specifically, the control system for recovering bromine in the vent scrubber of the oxidation tail gas is provided with a feed flow control unit, an MVR unit bromide ion concentration control unit, a filtration unit bromide ion concentration control unit, and a membrane separation unit bromide ion concentration unit.

[0054] More specifically, the feed flow control unit is configured to control the feed flow, and the separator liquid level fluctuates between 30% and 85% through feed flow control. Preferably, it fluctuates slightly around any set value between 35% and 85%.

[0055] More specifically, the bromide ion concentration control unit of the MVR unit is configured to increase the frequency of the compressor and the amount of supplementary steam to control the bromide ion concentration of the feed liquid exiting the MVR unit within a preset range.

[0056] More specifically, the bromide ion concentration control unit of the filtration unit is configured to: increase the rotation speed of the centrifugal filter, increase the residence time of the filtrate in the filter; and reduce the temperature of the filtrate.

[0057] More specifically, the membrane separation unit bromide ion concentration control unit is configured to: increase the voltage of the membrane separation machine; and increase the current of the membrane separation machine.

[0058] The control system for bromine recovery in the oxidation tail gas venting washing tower is also provided with a pressure difference detection control unit, which is configured to: detect the pressure difference of the membrane separation inlet and outlet pipelines, and when the pressure difference is too large, reduce the feed amount, thereby controlling the feed amount of the membrane separation unit.

[0059] like Figure 3 As shown, the control system for bromine recovery in the oxidation tail gas venting washing tower is connected to the oxidation unit of the PTA device. The entire process of bromine recovery is controlled by the control system for bromine recovery in the oxidation tail gas venting washing tower, so that bromine is recovered from the wastewater discharged from the bottom of the oxidation tail gas venting washing tower and re-enters the brominating agent tank for recycling.

[0060] Specifically, the oxidation unit is an exothermic reaction, where the heat of reaction is removed by evaporation of the solvent and reaction water. Flash steam from the reactor enters a condensation system at the top of the reactor, where nearly all the solvent and water are condensed. Each reactor has a condensation system consisting of five condensers connected in series. The uncondensed gas from the oxidation reactor's tail gas condenser, known as high-pressure tail gas, passes through a high-pressure absorption tower, where it is scrubbed with cold acetic acid and cold process water to recover paraxylene, methyl acetate, and acetic acid. The tail gas exiting the high-pressure absorption tower is then collected, pumped, and fed to the oxidation reactor for catalytic combustion, converting hydrocarbons, CO, methyl bromide, and other components into CO2, H2O, HBr, and Br2. The treated tail gas then flows to a tail gas expander for energy recovery. Finally, it enters a tail gas vent scrubber, where it is scrubbed with an alkaline solution to remove bromine compounds. The gas is then discharged to the atmosphere through a high-altitude exhaust pipe, with the remaining liquid being treated in a wastewater treatment unit.

[0061] Specifically, the oxidation intermediates and by-products generated in the oxidation reaction are further reacted into terephthalic acid in the secondary reactor to improve the conversion rate and quality; the normal pressure tail gas containing acetic acid discharged from the equipment in the PTA device and the tail gas from the secondary reactor are washed in the normal pressure washing tower using process water and solvent to remove acetic acid and methyl acetate, the tail gas is then removed of hydrocarbons, CO, methyl bromide, etc. through the low pressure incineration system, and finally discharged into the atmosphere through the high air exhaust pipe after being washed by alkali to remove bromide compounds.

[0062] As can be understood by those skilled in the art, in the conventional treatment technology, the wastewater flow at the bottom of the oxidation tail gas venting washing tower is divided into two streams by the tower bottom pump, one of which is recycled into the venting washing tower, and the other is sent to the wastewater treatment device. In this preferred embodiment of the present application, due to the provision of the control system for bromine recovery in the oxidation tail gas venting washing tower, the wastewater sent to the wastewater treatment station can be separated into the bromine recovery unit separator for evaporation and concentration, the steam flashed from the top of the separator is pressurized by a compressor, and the pressurized steam is used to heat the circulating liquid at the bottom of the separator, and the condensate is discharged into the condensate system. The concentrated liquid at the bottom of the separator is delivered by a circulating pump and divided into two streams, one of which is recycled for evaporation, and the other is sent to a filtering unit to separate sodium carbonate crystals. The filtrate mainly composed of sodium bromide and sodium acetate is sent to a membrane separation unit. High-purity HBr and HAc obtained through membrane separation can be recycled into the oxidation unit.

[0063] According to another aspect of the present application, there is also provided a control device for bromine recovery in an oxidation tail gas venting washing tower, which comprises a software application program, a memory for storing the software application program, and a processor for executing the software application program. The programs of the software application program can correspondingly perform the steps in the control method for bromine recovery in the oxidation tail gas venting washing tower of the present application.

[0064] As can be understood by those skilled in the art, the present application has been described with reference to the flowcharts and / or block diagrams of the method, system and computer program product according to the present application. Each block in the flowcharts and / or block diagrams, and the combination of blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions (executed by the processor of the computer or other programmable data processing device) produce the functions specified in one or more blocks of the flowcharts and / or block diagrams.

[0065] Those skilled in the art will understand that the above description and the accompanying drawings are only examples of the embodiments of the present application and do not limit the present application. The purpose of the present application has been fully and effectively achieved. The functional and structural principles of the present application have been demonstrated and described in the embodiments, and the embodiments of the present application can be modified or changed in any way without departing from the principles.

Claims

1. A method for controlling bromine recovery in an oxidation tail gas venting scrubber, characterized in that: The control method for bromine recovery in the oxidation tail gas venting scrubber comprises the following steps: Detect the bottom wastewater from the oxidation tail gas venting scrubber entering the separator; Control the wastewater discharged from the bottom of the scrubber to enter the bromine recovery unit separator for evaporation and concentration; Control the flash steam from the top of the separator to enter the steam compressor for pressurization, wherein the pressurized steam heats the circulating liquid at the bottom of the separator, and the condensate is discharged to the condensate system for steam circulation process; The concentrated liquid is generated at the bottom of the separator, and the concentrated liquid at the bottom of the separator is controlled to be transported by a circulating pump and divided into two streams, one of which is circulated and evaporated, and the other is controlled to be input into the filtration unit to separate and filter out the sodium carbonate crystals; controlling the filtrate whose main components are sodium bromide and sodium acetate to enter the membrane separation unit to perform membrane separation; and The hydrogen bromide and acetic acid are obtained through membrane separation in the membrane separation unit and are controlled to be re-inputted into the brominating agent device of the oxidation unit for recycling; Among them, an intelligent network computing model is established to perform real-time online analysis of the discharge concentration. When the discharge concentration of the concentrator needs to be increased, a concentration-increasing signal is sent to the MVR unit, filtration unit, and membrane separation unit, thereby increasing the bromide ion concentration. Among them, the intelligent network calculation model is called, with the separator feed flow, compressor frequency, supplementary steam volume, filter speed, membrane separator voltage and current as the operating variables, and the separator liquid level, pressure and temperature at the top of the separator, pressure and temperature at the bottom of the separator, concentrate concentration after membrane separation, recovery liquid concentration after the filtration unit, and final recovery liquid concentration as the controlled variables. The mapping relationship between the two is obtained, and then AI data mining is carried out. The algorithm model is selected from fully connected neural network, extreme gradient boosting decision tree, random forest, support vector machine, and linear regression; Among them, a liquid control valve is set on the feed line to control the separator liquid level to fluctuate slightly around any set value between 30% and 85% through the feed flow rate; Among them, the intelligent network calculation model is called to control the heat entering the evaporator according to the preset fluctuation range of the online feed concentration, thereby affecting the evaporation amount to ensure that the CO3 content of the liquid out of the MVR unit is 2- Ion concentration, Na + The ion concentration and bromide ion concentration fluctuate within the preset range; the factors affecting the evaporation rate include the pressure and temperature at the top of the separator and the pressure and temperature at the bottom of the separator. The top and bottom temperatures of the separator are adjusted by adding steam and the frequency of the compressor, and the bottom and top pressures of the separator are adjusted by the speed of the compressor, thereby affecting the evaporation rate inside the separator to ensure that the feed liquid leaves the MVR unit CO3 2- ions, Na + ion concentration and bromide ion concentration are within the preset range; Among them, the intelligent network calculation model is called, and the filtration unit adjusts the filter speed, the residence time of the filtrate in the filtration unit and the temperature of the filtrate according to the fluctuation of the feed liquid concentration; The control method for bromine recovery in the oxidation tail gas venting washing tower further includes the steps of: adjusting the filtrate feed rate of the filter unit according to the pressure difference before and after the filter unit feed line; controlling the pressure difference of the filter unit inlet and outlet pipelines, and reducing the feed rate when the pressure difference is too large, thereby controlling the feed rate of the filter unit.

2. The method for controlling bromine recovery in an oxidation tail gas venting scrubber according to claim 1, wherein the method for controlling bromine recovery in an oxidation tail gas venting scrubber further comprises the steps of increasing the bromide ion concentration in an MVR unit, adjusting the compressor frequency, and adjusting the amount of supplementary steam, and increasing the compressor frequency and the amount of supplementary steam.

3. The method for controlling bromine recovery in an oxidation tail gas venting scrubber according to claim 1 , wherein the method for controlling bromine recovery in an oxidation tail gas venting scrubber further comprises the steps of increasing the bromide ion concentration in the filtration unit by increasing the rotation speed of the centrifugal filter to increase the residence time of the filtrate in the filter; and reducing the temperature of the filtrate.

4. The method for controlling bromine recovery in an oxidation tail gas venting scrubber according to claim 1, wherein the method for controlling bromine recovery in an oxidation tail gas venting scrubber further comprises the steps of increasing the bromide ion concentration in a membrane separation unit: increasing the voltage of the membrane separator; and increasing the current of the membrane separator.

5. A control system for bromine recovery in an oxidation tail gas venting scrubber, applying the control method for bromine recovery in an oxidation tail gas venting scrubber according to any one of claims 1 to 4, characterized in that: The control system for bromine recovery in the oxidation tail gas venting washing tower includes a separator, a steam compressor, a filtration unit and a membrane separation unit. The control system for bromine recovery in the oxidation tail gas venting washing tower is provided with a feed flow control unit, an MVR unit bromide ion concentration control unit, a filtration unit bromide ion concentration control unit and a membrane separation unit bromide ion concentration unit; the feed flow control unit is configured to: perform feed flow control, and control the separator liquid level to fluctuate between 30% and 85% by the feed flow; the MVR unit bromide ion concentration control unit is configured to: perform compressor frequency increase and supplementary steam amount increase, and control the bromide ion concentration of the feed liquid out of the MVR unit to be within a preset range; the filtration unit The bromide ion concentration control unit is configured to: increase the rotation speed of the centrifugal filter, increase the residence time of the filtrate in the filter; and reduce the temperature of the filtrate; the bromide ion concentration control unit of the membrane separation unit is configured to: increase the voltage of the membrane separator; and increase the current of the membrane separator; the control system for bromine recovery in the oxidation tail gas venting washing tower is also provided with a pressure difference detection control unit, which is configured to: detect the pressure difference of the membrane separation inlet and outlet pipelines, and when the pressure difference is too large, reduce the feed amount, thereby controlling the feed amount of the membrane separation unit; the control system for bromine recovery in the oxidation tail gas venting washing tower is connected to the oxidation unit of the PTA device, and the entire process of bromine recovery is controlled by the control system for bromine recovery in the oxidation tail gas venting washing tower. The process is controlled to recover bromine from the wastewater discharged from the bottom of the oxidation tail gas venting and washing tower, and then re-enter the brominating agent tank for recycling. The oxidation unit is an exothermic reaction, and the reaction heat is carried away by the evaporation of the solvent and the water generated by the reaction. The flash steam of the reactor enters the condensation system at the top of the reactor. Each reactor has a set of condensation systems, including five condensers in series. The uncondensed gas from the oxidation reactor tail gas condenser is high-pressure tail gas and passes through a high-pressure absorption tower. It is washed with cold acetic acid and cold process water to recover paraxylene, methyl acetate and acetic acid. The tail gas from the high-pressure absorption tower is collected, pumped and supplied to the oxidation reactor for catalytic combustion to convert hydrocarbons, CO and methyl bromide into CO2, H2O, HBr and Br2. The treated tail gas is sent to the tail gas expander to recover energy, and finally enters the tail gas venting scrubber, where it is washed with an alkaline solution to remove bromine-containing compounds and discharged into the atmosphere through a high-altitude exhaust pipe. The remaining liquid is sent to the wastewater treatment device for treatment. Among them, the oxidation intermediates and by-products generated by the oxidation reaction are further reacted into terephthalic acid in the secondary reactor to improve the conversion rate and quality. The atmospheric pressure tail gas containing acetic acid discharged by the equipment in the PTA unit and the tail gas from the secondary reactor, and the low-pressure tail gas enter the atmospheric pressure scrubber, where they are washed with process water and solvent to remove acetic acid and methyl acetate. The tail gas is then sent to the low-pressure incineration system to remove hydrocarbons, CO, and methyl bromide. Finally, it enters the tail gas venting scrubber, is washed with alkaline solution to remove bromine-containing compounds, and is discharged into the atmosphere through a high-altitude exhaust pipe.The bromine recovery control system in the oxidation tail gas venting scrubber feeds wastewater from the wastewater treatment station into a bromine recovery unit separator for evaporation and concentration. Flash vapor from the top of the separator is pressurized by a compressor. The pressurized vapor heats the circulating fluid at the bottom of the separator, and the condensate is discharged into the condensate system. The concentrated fluid at the bottom of the separator is pumped by a circulating pump and split into two streams. One stream is circulated for evaporation, and the other stream is fed into a filtration unit to separate sodium carbonate crystals. The filtrate enters a membrane separation unit, where high-purity HBr and HAc are separated by membrane separation and returned to the oxidation unit for recycling.

6. A control system for bromine recovery in an oxidation tail gas venting scrubber, characterized in that: The control system for bromine recovery in the oxidation tail gas venting scrubber includes multiple hardware function modules, each of which is used to correspondingly execute the steps in the control method for bromine recovery in the oxidation tail gas venting scrubber described in any one of claims 1 to 4.

7. A PTA device oxidation unit, characterized in that: The oxidation unit of the PTA device is connected to the control system for bromine recovery in the oxidation tail gas venting washing tower according to claim 6, and the control system for bromine recovery in the oxidation tail gas venting washing tower recovers bromine from the wastewater discharged from the bottom of the oxidation tail gas venting washing tower, and the recovered bromine re-enters the brominating agent tank of the oxidation unit of the PTA device for recycling.

8. A control device for bromine recovery in an oxidation tail gas venting scrubber, characterized in that: include: Memory, for storing software applications, A processor is used to execute the software application, each program of the software application correspondingly executing the steps of the control method for bromine recovery in the oxidation tail gas venting scrubber according to any one of claims 1 to 4.

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