A multi-quality crystallization and resource recovery system for high-salinity industrial wastewater engineering

Abstract

This invention relates to the field of industrial wastewater treatment and resource recovery technology, and discloses a fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering. The system includes: a water quality reconstruction unit for receiving high-salinity concentrated water and performing deep treatment to produce clean raw water; a membrane-based precision salt separation unit for separating the clean raw water into sodium chloride-rich brine and sodium sulfate-rich brine; a fractional crystallization and purification scale prevention unit, including a freeze / evaporation crystallization sub-unit for treating sodium sulfate-rich brine and an MVR evaporation crystallization sub-unit for treating sodium chloride-rich brine; and an intelligent collaborative control center that communicates with the water quality reconstruction unit, the membrane-based precision salt separation unit, and the fractional crystallization and purification scale prevention unit. This invention achieves scale prevention and product quality synergy through full-chain closed-loop cascade control, dynamic self-adjustment of pretreatment depth, membrane-based secondary nanofiltration coupled with concentration adjustment to improve recovery rate, and dual-parameter seed crystal activity management, ultimately producing high-purity industrial salt.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment and resource recovery technology, and in particular to a fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering. Background Technology

[0002] Zero discharge and resource utilization of industrial wastewater are key pathways to solving high-salinity wastewater pollution and achieving a circular economy. Industries such as electroplating parks, titanium dioxide production, and coal chemical processing generate large quantities of high-salinity wastewater rich in sodium chloride, sodium sulfate, heavy metals, organic matter, complexes, and other complex components.

[0003] Existing fractional crystallization and resource recovery systems mainly consist of pretreatment units, membrane separation units, and evaporation crystallization units. However, in practical engineering applications, they generally face the following bottlenecks: First, the heat exchange surfaces of evaporation crystallizers are prone to scaling and clogging due to the deposition of scale layers such as calcium sulfate and silicates. Although traditional chemical softening or single-seed crystal methods can alleviate this, they cannot adapt to complex water quality fluctuations. Moreover, after long-term circulation, the activity of the seed crystals is easily reduced due to the adsorption of impurities, which in turn contaminates the product crystals, resulting in substandard salt purity and whiteness. Second, frequent fluctuations in influent water quality and load cause the operating window of the crystallization process to shift. General control strategies are difficult to adapt to the differentiated scaling and crystallization behaviors of different wastewaters such as electroplating and titanium dioxide, which have different hardness, organic matter, and heavy metals. Third, each treatment unit is mostly controlled independently, lacking a closed-loop linkage from the final product quality to the depth of front-end pretreatment, resulting in waste of reagents, high energy consumption, and difficulty in stabilizing product quality.

[0004] Therefore, there is an urgent need for a system that can deeply integrate membrane-based precise salt separation, intelligent scale prevention, purification and crystallization, and full-process collaborative control, so as to stably produce high-purity industrial salt products while operating continuously without scale for a long time, and achieve true high-value resource recovery. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a fractional crystallization and resource recovery system for high-salt industrial wastewater engineering. Through full-chain closed-loop cascade control, dynamic self-adjusting of pretreatment depth, membrane-based secondary nanofiltration coupled with concentration adjustment to improve recovery rate, dual-parameter seed crystal activity management to achieve synergistic scaling prevention and product quality, and supplemented by scenario-based anti-scaling and conflict arbitration, high-purity industrial salt is ultimately produced.

[0006] The objective of this invention can be achieved through the following technical solutions: The first aspect of this disclosure provides a fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering, comprising: The water quality reconstruction unit is used to receive high-salinity concentrated water and perform advanced treatment to produce clean raw water. The membrane-based precision salt separation unit is used to separate clean raw water into sodium chloride-rich brine and sodium sulfate-rich brine. The fractional crystallization and purification scale prevention unit includes a freeze / evaporation crystallization sub-unit for treating sodium sulfate-rich brine and an MVR evaporation crystallization sub-unit for treating sodium chloride-rich brine. The intelligent collaborative control center communicates with the water quality reconstruction unit, the membrane-based precise salt separation unit, and the fractional crystallization, purification, and scale prevention unit. The mother liquor discharge branch of the fractional crystallization and purification scale prevention unit is equipped with an online TOC monitoring probe and an online heavy metal monitoring probe. The crystallizer product discharge pipeline is equipped with an online crystal purity / whiteness monitoring probe, and the crystallizer circulation pipeline is equipped with an online turbidity monitoring probe. Each crystallizer is equipped with an integrated device for seed circulation and mother liquor purification. This device includes at least a seed induction zone, an online turbidity monitoring probe, a hydrocyclone separator, an automatic regulating valve for the mother liquor discharge branch, and a new seed replenishment metering and dosing device. The intelligent collaborative control center is configured to perform full-chain cascade regulation based on detection data from TOC, heavy metals, and crystal purity / whiteness monitoring probes, and to independently implement dynamic management of seed activity for each crystallizer based on the coupled data from the online turbidity monitoring probe and the online crystal purity / whiteness monitoring probe.

[0007] As a preferred embodiment of the present invention, the water quality reconstruction unit includes a multi-source catalytic oxidation module and a selective adsorption and fine filtration module connected in sequence. The intelligent collaborative control center is further configured to generate targeted instructions based on the type and combination relationship of the degradation signals: In response to signals of deterioration in mother liquor TOC or deterioration in crystal whiteness, instructions are generated to increase the oxidation intensity of the multi-source catalytic oxidation module or to extend its reaction residence time. In response to the heavy metal degradation signal of the mother liquor, instructions to enhance the selective adsorption and fine filtration module are generated first, and a compensatory oxidation instruction is generated simultaneously based on cascade analysis to determine when heavy metal penetration and insufficient oxidative complex breaking are correlated. In response to crystal purity degradation occurring alone, the water quality reconstruction unit is suppressed and seed activity dynamic management is triggered preferentially; in response to crystal purity degradation accompanied by TOC or whiteness degradation, organic matter penetration is determined to be a common factor and the depth adjustment of the water quality reconstruction unit is executed. When generating instructions to extend the reaction dwell time, the intelligent collaborative control center is also configured to: The increment of oxidant dosage is calculated based on the TOC deviation and whiteness deviation of each control cycle; The minimum theoretical hydraulic residence time required is determined based on the current TOC deviation and the pre-stored TOC-residence time correlation curve. When the minimum theoretical hydraulic residence time does not exceed the current maximum available hydraulic residence time of the multi-source catalytic oxidation module, an extended residence time instruction is generated and the target influent flow rate is calculated. During the execution of the extended residence time, the online flow meter data on the pipeline of the multi-source catalytic oxidation module is monitored simultaneously. When the influent flow rate is lower than the preset minimum anti-short flow threshold, the flow rate is stopped from being further reduced. When the minimum theoretical hydraulic residence time exceeds the maximum available hydraulic residence time, the option to extend the residence time is abandoned, and instead a higher compensatory oxidant increment instruction based on the organic pollution load equivalent deviation is generated.

[0008] As a preferred embodiment of the present invention, the membrane-based precise salt separation unit includes a high-pressure nanofiltration system and a secondary nanofiltration concentration device, wherein the secondary nanofiltration concentration device receives the cryogenic mother liquor from the freezing / evaporation crystallization subunit; The permeate water from the high-pressure nanofiltration system and the permeate water from the secondary nanofiltration concentration device are combined in the main pipe to form a mixed sodium chloride-rich brine. An online conductivity probe and a proportional regulating valve are installed at the point of convergence. The intelligent collaborative control center is also configured to: calculate the real-time concentration of sodium chloride based on the real-time data from the online conductivity probe, combined with the conductivity-sodium chloride concentration conversion model and temperature compensation curve; and generate an opening adjustment command based on the deviation between the real-time concentration and the preset target concentration, and send it to the proportional control valve after safety constraint verification, so as to stabilize the concentration of mixed brine entering the MVR evaporation crystallization sub-unit.

[0009] As a preferred embodiment of the present invention, the integrated device for seed circulation and mother liquor purification in each crystallizer includes: The seed crystal induction zone is located on the crystallizer circulation pipeline; The online turbidity monitoring probe is installed on the circulation pipeline downstream of the seed induction zone; The online crystal purity / whiteness monitoring probe is installed on the crystallizer product discharge pipeline; A hydrocyclone separator is installed on the crystallizer circulation pipeline; The mother liquor discharge branch is located at the overflow outlet of the hydrocyclone separator and is equipped with the automatic regulating valve. The new seed crystal replenishment metering and dosing device is connected to the seed crystal induction region; When the intelligent collaborative control center independently implements dynamic management of seed activity for each crystallizer, it is configured as follows: Read the online turbidity value of the corresponding crystallizer and online crystal purity value Or whiteness value ; Will Maintaining the lower limit of the preset seed concentration Comparison, will or Compared with the preset quality lower limit or Based on the comparison, the current operating condition is determined to belong to one of the following four categories: Operating Condition I: and or and ; Operating Condition II: and or and ; Operating Condition III: and or and ; Operating Condition IV: and or and ; Based on the determined operating condition category, the independent adjustment of the mother liquor discharge branch ratio, the new seed crystal replenishment acceleration rate, and the hydrocyclone stage efficiency is calculated and executed in a deviation-driven manner. Operating condition II is determined to be a decrease in seed crystal activity, operating condition III is determined to be an insufficient number of seed crystals, and operating condition IV is determined to be an insufficient number of both seed crystal activity and seed crystals.

[0010] As a preferred embodiment of the present invention, the intelligent collaborative control center is pre-configured with a scene mode library that includes at least an electroplating mode and a titanium dioxide mode, and is further configured as follows: Real-time acquisition of boiling point rise data B and supersaturation data S from the MVR evaporation and crystallization sub-unit; Call the weight coefficient corresponding to the current scene mode , In the electroplating mode Titanium dioxide mode Calculate the comprehensive risk value In the formula , The baseline warning threshold; when R When the value exceeds 1, an effect switching command is triggered. Before the effect switching command is executed, a command is sent in advance to the new seed replenishment metering and dosing device and the automatic regulating valve of the mother liquor discharge branch of the corresponding crystallizer to increase the new seed addition rate and temporarily reduce the mother liquor discharge split ratio in order to increase the effective seed quantity in the circulation loop to absorb the supersaturation disturbance.

[0011] As a preferred embodiment of the present invention, the intelligent collaborative control center is further configured to: arbitrate according to a preset priority when multiple deterioration signals triggering adjustment commands conflict within the same control cycle. The first priority is product quality assurance; instructions triggered by the deterioration of mother liquor heavy metal concentration or crystal purity will be executed first. The second priority is system anti-scaling protection; the effect switching command triggered by abnormal boiling point rise or supersaturation takes precedence over the normal adjustment command. The third priority is operational economy. Under the premise of satisfying the first two priorities, the adjustment combination with the lowest overall energy consumption or chemical consumption is selected. If the flow restriction action caused by prioritizing quality or scale prevention conflicts with the economic target, the extended residence time scheme is abandoned, a more compensatory oxidant increment scheme is adopted, and the instruction to reduce the influent flow rate is removed from the final instruction set.

[0012] The second aspect of this disclosure provides a method for fractional crystallization and resource recovery in high-salinity industrial wastewater treatment projects, applied to a fractional crystallization and resource recovery system for high-salinity industrial wastewater treatment projects as described above, including the following steps: High-salinity concentrated water is reconstructed to produce clean raw water; Clean raw water is precisely separated into sodium chloride-rich brine and sodium sulfate-rich brine using a membrane method; Sodium sulfate-rich brine was subjected to freeze / evaporation crystallization, and sodium chloride-rich brine was subjected to MVR evaporation crystallization, while maintaining seed crystal circulation during the crystallization process; The following closed-loop control steps are executed simultaneously during the crystallization process: The system can acquire data on the TOC concentration, heavy metal concentration, and purity / whiteness of the product crystals of the mother liquor online, and also acquire data on the turbidity of the circulating mother liquor in the crystallizer online. When at least one of the following factors—TOC concentration, heavy metal concentration, crystal purity, and crystal whiteness—shows a deterioration trend, a targeted instruction is generated based on the type of deterioration and its combination relationship, and feedback is used to adjust the depth of the water quality reconstruction treatment or the operating parameters of the membrane-based precise salt separation. Furthermore, the turbidity data is coupled with the purity / whiteness data. The operating condition category is determined based on the comparison results of turbidity and preset seed concentration maintenance lower limit and purity / whiteness and preset quality lower limit. Based on the operating condition category, at least one of the following is independently adjusted: mother liquor outflow branch ratio, new seed replenishment acceleration rate and hydrocyclone classification efficiency.

[0013] Furthermore, the generation of targeted instructions based on degradation types and their combinations includes: When the TOC of the mother liquor deteriorates or the whiteness of the crystals deteriorates, the oxidation intensity of the multi-source catalytic oxidation is increased or the reaction residence time is extended. When the current maximum available residence time cannot meet the requirements, a higher compensating oxidant increment is adopted. The logic for generating the higher compensating oxidant increment is: based on the difference between the current TOC value and the concentration that can be treated at the maximum residence time and the organic pollution load equivalent deviation calculated according to the historical data association model, multiplied by the compensation gain coefficient. When heavy metal deterioration occurs in the mother liquor, selective adsorption treatment should be strengthened first, and the TOC change trend should be combined to determine whether compensatory oxidation regulation is generated simultaneously. When crystal purity deterioration occurs alone, water quality reconstruction adjustment is not triggered, but crystal activity management is adjusted first; when crystal purity deterioration is accompanied by TOC or whiteness deterioration, it is determined to be organic matter penetration and water quality reconstruction depth adjustment is performed simultaneously. When multiple deterioration trends occur within the same control cycle and the corresponding feedback control commands conflict, arbitration shall be performed according to the following priority: Adjustments triggered by deterioration in mother liquor heavy metal concentration or crystal purity will be prioritized. Next, the effect switching is performed based on the abnormal boiling point rise or supersaturation. Under the premise that the aforementioned priorities are met, select the adjustment combination with the lowest energy consumption or reagent consumption; If prioritizing quality or scale prevention necessitates flow restriction, and this flow restriction conflicts with economic objectives, then the extended residence time option should be abandoned, and a more compensatory incremental oxidant option should be adopted instead.

[0014] Furthermore, the feedback adjustment of the operating parameters for the membrane-based precise salt separation includes: When the TOC concentration of the mother liquor continues to rise, increase the operating pressure of the high-pressure nanofiltration system to enhance the organic matter rejection rate, or adjust the feed flow rate or operating pressure of the secondary nanofiltration concentration unit. Furthermore, the conductivity of the two sodium chloride-rich brine streams after merging is acquired in real time, and converted into the real-time sodium chloride concentration after temperature compensation. Based on the deviation between the real-time concentration and the target concentration, the opening of the proportional control valve at the merging point is adjusted to stabilize the concentration of the mixed brine entering the MVR evaporation and crystallization process. The independent adjustment based on operating condition category includes: When the turbidity meets the standard and the purity / whiteness decreases, it is determined that the seed crystal activity has declined. The solution is to increase the mother liquor discharge ratio, increase the new seed crystal addition rate, and improve the hydrocyclone separator classification efficiency. When the turbidity is insufficient but the purity / whiteness meets the standards, the main approach is to supplement with new seed crystals. When both are insufficient, simultaneous external discharge, supplementation, and enhanced hierarchical separation are performed. Once both parameters meet the target and remain stable for the preset period, restore each adjustment value to the baseline value and switch to steady-state monitoring.

[0015] Furthermore, it also includes: Real-time monitoring of boiling point rise and supersaturation of MVR evaporation and crystallization; calculation of comprehensive risk value based on the corresponding weighting coefficients according to preset scenario modes. When the comprehensive risk value exceeds the limit and triggers the effect switching, before the effect switching is executed, the new seed injection acceleration rate of the corresponding crystallizer is increased in advance and the mother liquor discharge ratio is temporarily reduced to increase the effective seed quantity in the circulation loop to absorb the disturbance. After the effect switching action is executed for a preset short duration, the disturbance is determined based on the real-time supersaturation or boiling point rise data. If the disturbance is eliminated, the parameters of the evaporation condition and the seed crystal circulation device are restored to the reference values ​​before the effect switching. If the disturbance is not eliminated, the current effect switching state is maintained and continuous monitoring is performed.

[0016] The beneficial effects of this invention are: This invention constructs a closed-loop system encompassing water quality reconstruction, membrane desalination, fractional crystallization, and an intelligent control system. It feeds back the final product quality indicators (crystal purity / whiteness, mother liquor TOC, and heavy metal concentration) to the pretreatment stage in real time for cascaded regulation. This allows the advanced oxidation depth and adsorption treatment intensity to dynamically adjust based on the deterioration trend of crystal quality, ensuring the cleanliness of the raw water from the source. The membrane desalination unit recovers the frozen mother liquor through secondary nanofiltration and combines it with closed-loop concentration adjustment, improving sodium sulfate recovery and stabilizing the feed concentration for evaporation crystallization. The fractional crystallization unit uses turbidity-purity / whiteness dual-parameter coupling to independently control each crystallizer. The system performs coordinated control of operating condition identification, mother liquor diversion, seed replacement, and grading efficiency. While maintaining the seed concentration required for scale prevention, it actively discharges deactivated seed crystals and replenishes new seed crystals, solving the problem of product contamination caused by traditional seed circulation. This enables the stable production of high-purity, high-whiteness industrial salt under long-term scale-free operation. Combined with the pre-set scenario mode's boiling point rise-supersaturation composite anti-scale strategy and the seed pre-replenishment mechanism during effect switching, as well as the priority arbitration and compensation oxidation intensity substitution scheme for multi-objective conflicts, it effectively suppresses the risk of scaling in the evaporation system, eliminates coupling conflicts between units, and ultimately achieves efficient resource recovery of complex high-salt wastewater. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1This is a schematic diagram of a fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering provided by an embodiment of the present invention; Figure 2 This is a schematic diagram of the steps of a fractional crystallization and resource recovery method for high-salt industrial wastewater engineering provided by an embodiment of the present invention; Figure 3 This is a schematic diagram of the closed-loop control steps performed synchronously during the crystallization process, provided by an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This embodiment provides a fractional crystallization and resource recovery system for high-salinity industrial wastewater treatment projects, such as... Figure 1 As shown, it includes a water quality reconstruction unit, a membrane-based precise salt separation unit, a fractional crystallization and purification scale prevention unit, and an intelligent collaborative control center.

[0021] The water quality reconstruction unit is used to receive upstream high-salinity concentrated water and, based on product quality indicators fed back from within the system, to perform targeted deep treatment on the high-salinity concentrated water to produce clean raw water.

[0022] Understandably, the water quality reconstruction unit receives complex high-salt concentrate from an external membrane concentration unit (not shown), which, in addition to high concentrations of sodium chloride and sodium sulfate, also includes residual organic matter, complexes, and trace amounts of heavy metals or colloids from electroplating or titanium dioxide processes.

[0023] It should be noted that the product quality indicators fed back by the system include parameters that reflect the quality of the product itself and the risks of the process environment. Specifically, these include product quality indicators (crystal purity and crystal whiteness) and process environment risk indicators (TOC concentration and heavy metal concentration of the mother liquor).

[0024] The water quality reconstruction unit includes a multi-source catalytic oxidation module and a selective adsorption and fine filtration module connected in sequence. The multi-source catalytic oxidation module automatically adjusts the dosage of oxidant (such as ozone, hydrogen peroxide, etc.) and the reaction residence time based on the oxidation intensity setting value sent by the intelligent collaborative control center, breaks down stubborn complexes, and performs ring-opening and chain breaking on organic matter that affects the whiteness of the product.

[0025] The selective adsorption and fine filtration module is filled with special ion exchange resin or activated carbon to deeply remove trace heavy metals, fluoride ions and residual colloidal particles. Finally, the water is filtered through a precision filter to ensure the cleanliness of the effluent, producing clean raw water that is then sent to the next unit.

[0026] It should be noted that the setting of the treatment depth of the water quality reconstruction unit is based on the dynamic adjustment of the downstream crystallization quality feedback signal. When the intelligent collaborative control center obtains the process environment risk indicators or the product quality indicators in the product quality indicators and finds a deterioration trend, it determines the root cause according to the type of deterioration and generates targeted instructions: if the mother liquor TOC concentration, heavy metal concentration, or crystal whiteness decreases, it is determined that the water quality reconstruction unit is not treating sufficiently, and then an instruction is generated to increase the oxidation intensity of the multi-source catalytic oxidation module or switch / regenerate the selective adsorption module; if the crystal purity decreases alone, the seed activity dynamic management and control of the fractional crystallization and purification scale prevention unit is triggered first, until the downstream quality indicators return to the normal range.

[0027] The multi-source catalytic oxidation module automatically adjusts the dosage of oxidants such as ozone and hydrogen peroxide and the reaction residence time based on the oxidation intensity set value sent by the intelligent collaborative control center, including the following steps: Data Acquisition and Deterioration Trend Determination: TOC online monitoring probes and heavy metal online monitoring probes are installed on the mother liquor discharge branches of the MVR evaporation crystallization sub-unit and the freeze / evaporation crystallization sub-unit in the fractional crystallization and purification scale prevention unit, respectively. Online crystal purity / whiteness monitoring probes are installed on the crystallizer product discharge pipelines of the crystallizers in the MVR evaporation crystallization sub-unit and the freeze / evaporation crystallization unit, respectively. Each probe communicates with the intelligent collaborative control center via industrial Ethernet.

[0028] The logic for determining the deterioration trend of product quality indicators includes: When the moving average value of the TOC concentration in the mother liquor exceeds the preset TOC warning upper limit threshold over A consecutive sampling periods, a TOC degradation signal is output. When the sliding average value of the online crystal whiteness value over B consecutive sampling periods is lower than the preset lower limit threshold for whiteness, a whiteness degradation signal is output. When the sliding average value of the online crystal purity over E consecutive sampling periods is lower than the preset lower purity threshold, a purity degradation signal is output. When the moving average concentration of heavy metals in the mother liquor exceeds the preset heavy metal warning upper limit threshold over C consecutive sampling periods, a heavy metal degradation signal is output.

[0029] When any degradation signal is output by the degradation trend determination, the central control system initiates corresponding regulation based on the signal type: when a whiteness degradation or TOC degradation signal is output, the treatment depth adjustment of the water quality reconstruction unit is directly triggered; when a heavy metal degradation signal is output, the enhanced treatment of the adsorption module in the water quality reconstruction unit is directly triggered; when a purity degradation signal is output, the dynamic management and regulation of the seed activity of the fractional crystallization and purification scale prevention unit is triggered first, and this signal is used as an auxiliary judgment basis for the depth adjustment of the water quality reconstruction unit (if purity degradation occurs alone, the water quality reconstruction unit will not be triggered; if purity degradation is accompanied by TOC or whiteness degradation, organic matter penetration is determined to be the common cause, and the depth adjustment of the water quality reconstruction unit is executed synchronously according to the whole-chain cascade regulation).

[0030] Simultaneous calculation of adjustment amount and residence time: When the degradation trend is determined and a TOC degradation or whiteness degradation signal is output, the coupled calculation of oxidation intensity adjustment and reaction residence time is performed simultaneously. Oxidant increment calculation: When the trigger signal is TOC degradation or whiteness degradation, calculate the oxidant dosage increment: In the formula, , The preset gain coefficient, This represents the deviation between the current TOC moving average and the target value (if TOC degradation is not triggered, this deviation is considered to be 0). This represents the deviation between the target whiteness value and the current moving average (this deviation is considered 0 if whiteness degradation is not triggered). When the trigger signal is only heavy metal degradation, the current oxidant dosage should be maintained (i.e., ...). Simultaneously trigger the enhanced treatment of selective adsorption and fine filtration modules (switching or regenerating the adsorption tower); at the same time, continuously monitor the changing trends of mother liquor TOC concentration and heavy metal concentration. If further cascade analysis determines that heavy metal penetration is related to insufficient front-end oxidation complex breaking, then a compensatory oxidation intensity adjustment command is generated simultaneously.

[0031] Reaction residence time calculation: Based on the pre-stored TOC-residence time correlation curve, and based on the current... Determine the minimum theoretical hydraulic residence time required. Simultaneously, the current maximum available hydraulic retention time of the multi-source catalytic oxidation module is collected. (Determined by the effective volume of the reactor and the maximum allowable liquid level), comparisons are made: like If so, it is determined that the conditions for extension are met, according to the formula. ( V To effectively calculate the target influent flow rate (based on the reaction volume), And generate instructions to extend the residence time of the oxidation reaction; like If the physical constraints prevent the target from being met by simply extending the dwell time, then this adjustment option is abandoned, and a compensatory higher oxidant increment command (i.e., a compensatory oxidation intensity adjustment command) is generated instead. To meet the needs of deep processing.

[0032] It should be noted that the aforementioned compensatory oxidation intensity adjustment command The generation logic is as follows: ,in This is the difference between the current TOC value and the concentration that can be handled at the maximum residence time. The deviation of organic pollution load equivalent calculated based on historical data correlation models. To compensate for the gain coefficient. When the output heavy metal degradation signal is determined by cascade analysis to require compensation for oxidation intensity, a compensation oxidation intensity adjustment command is generated, and the residence time coupling calculation is not executed; other degradation signals (such as individual purity degradation) do not trigger this coupling calculation.

[0033] Command issuance and execution feedback: The calculated adjustment commands are sent to the corresponding actuators of the water quality reconstruction unit. Oxidant metering pump, executes new dosing rate setting; The inlet regulating valve is set to the target opening value for flow restriction (if the residence time extension command is in effect). The outlet regulating valve is linked with the inlet regulating valve to maintain the reactor liquid level balance. The valve group of the selective adsorption module executes the adsorption tower switching or regeneration procedure.

[0034] After completing the command action, each actuator returns a status feedback signal to confirm the execution of the command.

[0035] After issuing instructions to the corresponding actuator of the water quality reconstruction unit, the online flow meter data on the multi-source catalytic oxidation module pipeline is monitored simultaneously during the extended residence time execution. When the influent flow rate falls below the preset minimum short-circuit prevention threshold... At that point, stop further reducing the flow rate.

[0036] Continuously monitor product quality indicators such as TOC, whiteness, and heavy metals. When the moving average of each indicator returns to the normal range (i.e., the TOC and heavy metal concentrations of the mother liquor are below their respective upper warning thresholds, and the crystal whiteness and purity are above their respective lower quality thresholds), and remains stable for at least Q sampling cycles, the central system determines that the depth adjustment has met the standard, restores the oxidant dosage and hydraulic retention time to the basic set values, or maintains the current operating state of the adsorption module until the next deterioration trend signal is triggered.

[0037] The membrane-based precision salt separation unit is used to separate clean raw water into sodium chloride-rich brine and sodium sulfate-rich brine, and integrates a secondary salt separation circuit for receiving downstream freezing mother liquor. The nanofiltration concentrate from this secondary salt separation circuit is returned to the feed end of the freezing / evaporation crystallization sub-unit as sodium sulfate-rich reflux liquid to improve the total recovery rate of sodium sulfate.

[0038] Specifically, the membrane-based precision salt separation unit includes a high-pressure nanofiltration system for primary separation and a secondary nanofiltration concentration unit for receiving the mother liquor from the freezing / evaporation crystallization sub-unit; The membrane-based precision salt separation unit receives clean feed water from the water quality reconstruction unit and first enters the high-pressure nanofiltration system for main separation. The permeate side of the high-pressure nanofiltration membrane is sodium chloride-rich brine A, and the concentrate side is sodium sulfate-rich brine. The sodium sulfate-rich brine is directly sent to the freeze / evaporation crystallization sub-unit of the fractional crystallization and purification scale prevention unit.

[0039] The secondary nanofiltration concentration unit is specifically designed to receive the frozen mother liquor, still containing a small amount of sodium sulfate, produced from the downstream freezing / evaporation crystallization sub-unit. The frozen mother liquor first passes through a heat exchanger that exchanges heat with the secondary steam condensate from the MVR evaporation crystallization sub-unit, utilizing waste heat to raise its temperature to the optimal nanofiltration temperature range before entering this unit for secondary separation. The resulting product is a sodium chloride-rich brine B, which merges with the aforementioned sodium chloride-rich brine A in a main pipe to form a mixed sodium chloride-rich brine. An online conductivity probe and a proportional control valve are installed at the merging point. The intelligent collaborative control center adjusts the opening of the proportional control valve in real time based on conductivity data to control the concentration of the merged mixed sodium chloride-rich brine, which is then sent to the MVR evaporation crystallization sub-unit. The concentrate from the secondary nanofiltration concentration unit is returned to the feed end of the freezing / evaporation crystallization sub-unit as sodium sulfate-rich reflux liquid to improve the overall sodium sulfate recovery rate. This design forms a salt separation loop that integrates structure and energy.

[0040] Specifically, the intelligent collaborative control center adjusts the opening of the proportional regulating valve in real time based on conductivity data, including the following steps: Online concentration sensing: The intelligent collaborative control center acquires the conductivity data of the mixed brine in real time through an online conductivity probe, and calls up a pre-stored conductivity-sodium chloride concentration conversion model. Combined with the temperature compensation curve, it converts the conductivity data into the real-time sodium chloride concentration. .

[0041] It should be noted that the conductivity-sodium chloride concentration conversion model is established by using simulated brine from the high-salt wastewater being treated by this system under laboratory conditions. Standard solutions with different sodium chloride concentrations were prepared at a constant reference temperature (e.g., 25°C), and their conductivity values ​​were measured one by one. The "concentration-conductivity" function relationship was established through data fitting. The temperature compensation curve is obtained by measuring the conductivity change of the same standard solution at different temperatures and fitting the correction coefficient curve of conductivity with temperature change. Both models are pre-stored in the intelligent collaborative control center. During operation, the temperature compensation curve is first called according to the real-time water temperature to convert the measured conductivity into the equivalent value at the reference temperature, and then substituted into the conversion model to obtain the real-time sodium chloride concentration.

[0042] Concentration deviation calculation and adjustment amount generation: Read the preset target concentration (determined based on the optimal operating window of the MVR evaporation crystallization sub-unit). Calculate concentration deviation ,when Exceeding the preset concentration stability tolerance threshold At that time, Input Proportional-Integral Control Algorithm Calculate the opening adjustment amount of the proportional control valve. In the formula , These are the preset proportional gain and integral gain, respectively.

[0043] Safety constraint verification and command issuance: Verify the preset proportional control valve safety opening constraint conditions, including the upper limit of the opening. Lower limit of opening and opening rate of change limit If the calculated target opening If any of the above constraints are exceeded, the command will be trimmed to a safe boundary value. After verification, the target opening command is sent to the actuator of the proportional control valve to drive the valve stem and receive a valve position feedback signal to confirm execution.

[0044] Stability assessment and mode switching: After the command is executed, the real-time concentration of sodium chloride is continuously monitored. ,when If the condition is met for D consecutive sampling periods, the convergence concentration is determined to have reached a stable state. The current opening degree is maintained, and continuous monitoring mode is initiated. Exceeding the tolerance threshold again If necessary, immediately reactivate the adjustment process.

[0045] Through the above closed-loop control, the concentration of the mixed sodium chloride-rich brine entering the MVR evaporation crystallization sub-unit is precisely controlled, ensuring that the feed concentration of the crystallizer is stable within the optimal operating window, thereby avoiding abnormal crystal particle size distribution and purity reduction caused by fluctuations in feed concentration.

[0046] The fractional crystallization and purification scale prevention unit includes a freeze / evaporation crystallization sub-unit for treating sodium sulfate-rich brine and an MVR evaporation crystallization sub-unit for treating sodium chloride-rich brine. Both the freeze / evaporation crystallization unit and the MVR evaporation crystallization unit are equipped with an integrated device for seed circulation and mother liquor purification that couples turbidity and purity parameters.

[0047] Specifically, the integrated device for seed circulation and mother liquor purification coupled with dual parameters of turbidity and purity is respectively installed on the crystallizer of the freeze / evaporation crystallization sub-unit and the crystallizer of the MVR evaporation crystallization sub-unit of the fractional crystallization and purification scale prevention unit. Each integrated device includes: The seed crystal induction zone is located on the crystallizer circulation pipeline of the crystallizer. An online turbidity monitoring probe is installed on the crystallizer circulation pipeline, downstream of the seed induction zone; An online crystal purity / whiteness monitoring probe is installed on the crystallizer product discharge pipeline of the crystallizer. A hydrocyclone separator is installed on the crystallizer circulation pipeline; The mother liquor discharge branch is located at the overflow outlet of the hydrocyclone separator and is equipped with an automatic regulating valve. The new seed crystal replenishment metering and dosing device is connected to the seed crystal induction zone.

[0048] On the mother liquor discharge branch, TOC online monitoring probes and heavy metal online monitoring probes are also installed. The TOC online monitoring probes and heavy metal online monitoring probes establish communication with the intelligent collaborative control center through industrial Ethernet, and upload the detection data in real time for whole-chain cascade control.

[0049] The intelligent collaborative control center independently regulates each crystallizer based on the coupled data provided by the online turbidity monitoring probe and the online crystal purity / whiteness monitoring probe, and adjusts in real time the classification efficiency of the corresponding hydrocyclone separator, the flow ratio of the automatic regulating valve on the mother liquor discharge branch, and the dosing rate of the new seed crystal replenishment metering and dosing device.

[0050] Specifically, the intelligent collaborative control center independently regulates each crystallizer, including the following steps: Coupled data acquisition and operating condition determination: Read the online turbidity value of a specified crystallizer. and online crystal purity value (or whiteness value) Within a single control cycle, the selected product quality variable maintains a unique mapping, and the same variable is used throughout the entire chain; Maintain the lower limit of the preset seed concentration Compare, (or ) and the preset lower limit of product quality (or Compare the data to determine the current operating condition category: Operating Condition I: and (or ); Operating Condition II: and (or ); Operating Condition III: and (or ); Operating Condition IV: and (or ).

[0051] Adjustment Calculation: Based on the determined operating conditions, calculate the adjustment amounts for the following three control variables of the crystallizer: Mother liquor outflow branch flow ratio adjustment Operating Condition I Maintain the baseline shunt ratio Operating Condition II Operating Condition III Or slightly positive; under operating condition IV .

[0052] New seed crystal supplementation acceleration rate adjustment amount Operating Condition I Operating Condition II Operating Condition III Operating Condition IV .

[0053] Hydrocyclone separator classification efficiency adjustment Maintaining reference efficiency under operating condition I Operating Condition II Operating Condition III Or slightly negative; under operating condition IV .

[0054] above , , , , , , , , , All parameters are preset.

[0055] It should be noted that during operating condition II... When whiteness is used as the monitoring index, in the formula Replace with , Replace with Operating Condition II When whiteness is used as the monitoring index, in the formula Replace with , Replace with Operating Condition IV In the formula, α is the normalization coefficient for converting turbidity deviation into equivalent purity / whiteness deviation. When whiteness is used as the monitoring index, in the formula... Replace with , Replace with Operating Condition IV When whiteness is used as the monitoring index, in the formula Replace with , Replace with Regardless of whether purity or whiteness is used as the monitoring indicator, the selected product quality variable should maintain a unique mapping within a single control cycle, and the same variable should be used throughout the entire chain for data collection, judgment, and adjustment calculation.

[0056] Safety constraint verification and instruction issuance: Verify each calculated adjustment value: The diversion ratio of the mother liquor discharge branch does not exceed the preset upper limit. And its rate of change does not exceed the preset limit. The rate of new seed crystal addition shall not exceed the maximum addition capacity. And its rate of change does not exceed the preset limit. The hydrocyclone separator adjustment should not exceed the allowable operating range. After verification, independent instructions are issued to the actuators corresponding to the crystallizer: the opening setting value is sent to the automatic regulating valve on the mother liquor discharge branch, the acceleration rate setting value is sent to the new seed crystal replenishment metering and dosing device, and the parameter setting value is sent to the feed pump or regulating valve of the hydrocyclone separator; and status feedback signals are received from each actuator.

[0057] Effect monitoring and steady-state recovery: After the command is executed, the turbidity of the crystallizer is continuously collected. and purity (or whiteness) The data is updated in real time to determine the operating condition. After returning to operating condition I and maintaining it stably for at least U sampling cycles, the central control gradually restores the adjustment values ​​of the mother liquor outflow branch ratio, the new seed crystal replenishment acceleration rate, and the hydrocyclone stage efficiency to the baseline values, and enters steady-state monitoring mode; if the operating condition drifts again, the above steps are immediately reactivated.

[0058] Through the independent, dual-parameter coupled control of each crystallizer, this system achieves dynamic management of seed activity based on product purity: on the basis of maintaining the seed concentration required for scale prevention by turbidity feedback, product purity / whiteness is introduced as the criterion for seed activity. When purity or whiteness decreases, inactive seeds are actively discharged and fresh seeds are replenished, which solves the problem of product contamination caused by the circulation of seeds in the traditional seed method. It can stably produce high-purity, high-whiteness industrial salt products while operating without scale for a long time.

[0059] The intelligent collaborative control center communicates with the online monitoring probes and actuators of the water quality reconstruction unit, the membrane precision salt separation unit, and the fractional crystallization and purification scale prevention unit via industrial Ethernet or analog signal lines. It collects key process parameters and online product quality data of each unit in real time, and runs preset scenario modes and prediction models for different wastewater characteristics to perform integrated collaborative control of the three units.

[0060] The integrated collaborative control of the intelligent collaborative control center specifically includes: Full-chain cascade control of product quality indicator feedback: The intelligent collaborative control center receives detection data uploaded by the TOC online monitoring probe and the heavy metal online monitoring probe set on the mother liquor discharge branch of the fractional crystallization and purification scale prevention unit, as well as purity or whiteness degradation signals uploaded by the online crystal purity / whiteness monitoring probe. Based on their changing trends and combination relationships, it implements closed-loop control of the water quality reconstruction unit and the membrane-based precise salt separation unit, specifically including: (1) Reverse adjustment of the treatment depth of the water quality reconstruction unit: When the moving average of the mother liquor TOC concentration or crystal whiteness value shows a deterioration trend and exceeds the corresponding warning threshold, it is determined that the water quality reconstruction unit is not treating sufficiently, and an instruction is generated to increase the oxidant dosage of the multi-source catalytic oxidation module or extend its reaction residence time; when the moving average of the mother liquor heavy metal concentration shows an upward trend and exceeds the corresponding warning upper limit threshold, an instruction is generated first to strengthen the treatment of the selective adsorption and fine filtration module (including switching or regenerating the adsorption tower), and cascade analysis is performed in conjunction with the synchronously monitored trend of the mother liquor TOC concentration change. If the cascade analysis further determines that the heavy metal penetration is related to the insufficient front-end oxidation complex breaking, a compensatory oxidation intensity adjustment instruction is generated synchronously; when the moving average of the TOC concentration, whiteness value, heavy metal concentration and crystal purity is continuously lower than the corresponding warning lower limit threshold and is stably maintained for at least Q sampling cycles, an instruction is generated to reduce the oxidation intensity and restore it to the basic set value.

[0061] (2) Optimization and adjustment of operating parameters for the membrane-based precision salt separation unit: When the moving average of the mother liquor TOC concentration continuously increases, based on the whole-chain cascade analysis, it is determined that there is a risk of organic matter penetration in the front-end water quality reconstruction unit or the membrane-based precision salt separation unit. An instruction is generated to first check and increase the treatment depth of the water quality reconstruction unit, and then, as needed, an instruction is issued to the membrane-based precision salt separation unit to increase the operating pressure of the high-pressure nanofiltration system to enhance the retention rate of organic matter; the flow rate of the frozen mother liquor entering the secondary nanofiltration concentration unit or the operating pressure of the secondary nanofiltration unit is adjusted to control the concentration and flow rate of the sodium sulfate-rich reflux liquid to balance the salt separation efficiency and the membrane fouling rate. When the mother liquor TOC concentration returns to the normal range, the operating parameters are restored to the baseline value.

[0062] Closed-loop concentration control: The intelligent collaborative control center receives conductivity data uploaded by an online conductivity probe installed on the main confluence pipe of the two product water streams in the membrane precision salt separation unit, and performs closed-loop control of online concentration sensing, concentration deviation calculation and adjustment amount generation, safety constraint verification and command issuance, stability determination and mode switching (the specific control steps are consistent with the four steps of online concentration sensing, concentration deviation calculation and adjustment amount generation, safety constraint verification and command issuance, stability determination and mode switching in the membrane precision salt separation unit), so as to stabilize the concentration of the mixed sodium chloride-rich brine entering the MVR evaporation crystallization sub-unit at the preset target concentration.

[0063] Dynamic management of seed crystal activity based on product purity: The intelligent collaborative control center receives coupled data from online turbidity monitoring probes and online crystal purity / whiteness monitoring probes independently uploaded by each crystallizer. It independently performs closed-loop control of each crystallizer, including condition judgment, adjustment calculation, safety constraint verification and command issuance, effect monitoring and steady-state recovery (see the fractional crystallization and purification anti-scaling unit for specific control steps), so as to ensure that the product purity and whiteness meet the standards while maintaining the seed crystal concentration required for anti-scaling.

[0064] A scenario-adaptive composite anti-scaling control strategy: The intelligent collaborative control center has a pre-set scenario mode library that includes at least "electroplating mode" and "titanium dioxide mode". Under different scenario modes, the center monitors the boiling point rise data collected in real time from the MVR evaporation crystallization subunit of the fractional crystallization and purification anti-scaling unit. and supersaturation data The weighted comprehensive risk calculation is performed, and the model is as follows: ,in , This serves as the baseline warning threshold for this mode. , These are preset weighting coefficients. When the overall risk value... When the value exceeds 1, a trigger effect switching command is activated. This applies to electroplating mode. High warning weighting for boiling point rise; titanium dioxide mode This reflects the high representation weight of oversaturation.

[0065] Simultaneously with the issuance of the effect switching command, the central control system sends a coordinated action command to the seed circulation device of the MVR evaporation crystallization sub-unit. Specifically, before the effect switching action is executed, commands are sent to the new seed replenishment metering and dosing device and the automatic regulating valve of the mother liquor discharge branch corresponding to the crystallizer, respectively, to increase the dosing rate of the new seed replenishment metering and dosing device and temporarily reduce the flow ratio of the mother liquor discharge branch, thereby increasing the amount of effective seed in the circulation loop, absorbing the supersaturation disturbance caused by the effect switching, and preventing explosive nucleation. After the effect switching action has been executed for a preset short duration, the intelligent coordinated control system determines whether the disturbance has been eliminated based on real-time supersaturation or boiling point rise data. If eliminated, a command is generated to gradually restore the evaporation conditions and the parameters of the seed circulation device to the baseline values ​​before the effect switching, and enter steady-state monitoring. If not eliminated, the current effect switching state and coordinated action command are maintained, and the early warning weight coefficient in the risk calculation model is increased simultaneously, and monitoring continues until the disturbance is eliminated.

[0066] Multi-objective conflict resolution and priority arbitration: When the intelligent collaborative control center receives multiple degradation trend signals within the same control cycle, and the corresponding adjustment commands conflict (e.g., TOC degradation requires extending the oxidation residence time to reduce the influent flow rate, while the combined concentration closed-loop control requires maintaining a stable total influent flow rate to ensure mixing representativeness, creating a contradiction between upstream permeate rate and downstream demand), the center arbitrates according to preset priority rules: The first priority is product quality assurance; adjustment commands triggered by the deterioration of mother liquor heavy metal concentration or crystal purity take precedence over other commands. The second priority is system scale prevention protection, and the effect switching command triggered by abnormal boiling point rise or supersaturation takes precedence over the normal adjustment command. The third priority is operational economy. Under the premise of satisfying the first two priorities, the combination of adjustment schemes with the lowest overall energy consumption or reagent consumption is selected. If prioritizing product quality or scale prevention necessitates flow restriction (e.g., reducing influent flow to extend residence time), but this flow restriction conflict with other economic objectives such as maintaining system product water load and is rejected by arbitration, then the extended residence time scheme is proactively abandoned, and a more compensatory oxidant increment scheme is adopted instead. Furthermore, the influent flow reduction instruction generated for extending residence time is removed from the final instruction set. Synchronization will proceed as described in "Synchronization Judgment of Adjustment Amount and Residence Time". The compensatory instructions generated by the logic calculation are incorporated into the final set of coordinated instructions and issued.

[0067] Following arbitration, the central authority issues a coordinated set of instructions to each unit's execution agency to ensure consistent action across the entire system and avoid coupling conflicts arising from independent adjustments by each unit.

[0068] Through the aforementioned integrated and coordinated regulation, the intelligent collaborative control center weaves the water quality reconstruction unit, the membrane-based precise salt separation unit, and the fractional crystallization and purification scale prevention unit into a closed-loop linkage, realizing intelligent collaborative optimization across the entire chain from end product quality to front-end pretreatment depth, and from salt separation accuracy to crystallization purity.

[0069] This embodiment also provides a method for fractional crystallization and resource recovery of high-salinity industrial wastewater, such as... Figure 2-3 As shown, the steps include: During the fractional crystallization process, the turbidity data of the circulating mother liquor in the crystallizer and the purity / whiteness data of the product crystals are acquired online simultaneously. Turbidity data and purity / whiteness data are input into the intelligent collaborative control center for coupled analysis. Based on the comparison results of turbidity data with the preset seed concentration maintenance lower limit and purity / whiteness data with the preset product quality lower limit, the current operating condition category is determined. Understandably, the intelligent collaborative control center, upon system startup or after each adjustment to restore steady state, first establishes a set of baseline control parameters for each crystallizer to maintain steady-state operation. These baseline parameters include the baseline mother liquor discharge branch diversion ratio. , benchmark new seed crystal supplementation acceleration rate and the classification efficiency of the reference hydrocyclone separator .

[0070] Based on the determined operating condition category, corresponding collaborative control instructions are generated and executed. These instructions include at least one of the following: adjusting the mother liquor discharge branch flow ratio, increasing the new seed crystal replenishment acceleration rate, and improving the hydrocyclone classification efficiency. Specifically, when the seed crystal concentration is sufficient but product quality is declining, it is determined that the seed crystal activity is decreasing, and instructions are generated and executed to increase the mother liquor discharge branch flow ratio (calculated based on product quality deviation), increase the new seed crystal replenishment acceleration rate (calculated based on product quality deviation), and improve the hydrocyclone classification efficiency. When the seed crystal concentration is insufficient but product quality is normal, instructions primarily focused on replenishing new seed crystals are generated and executed. When both are insufficient, instructions for discharging deactivated seed crystals, replenishing new seed crystals, and enhancing classification separation are executed simultaneously. Meanwhile, the intelligent collaborative control center monitors the boiling point rise and supersaturation in real time, and decides whether to initiate the effect switching operation based on the preset scene mode. When it is initiated, it sends a collaborative action command to the seed crystal circulation system. The collaborative action command includes increasing the new seed crystal replenishment acceleration rate in advance and temporarily reducing the mother liquor outflow branch diversion ratio to increase the effective seed crystal amount in the circulation loop. The turbidity and purity / whiteness data are continuously monitored. When the condition is determined to return to operating condition I (i.e., the turbidity is not lower than the seed concentration maintenance lower limit and the product quality is not lower than its lower limit) and is stably maintained for the preset number of cycles, the adjustment values ​​of the mother liquor discharge branch diversion ratio, the new seed replenishment acceleration rate and the hydrocyclone classification efficiency are restored to the baseline values, and the system is switched to steady-state monitoring mode.

[0071] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A fractional crystallization and resource recovery system for high-salinity industrial wastewater treatment, characterized in that: include: The water quality reconstruction unit is used to receive high-salinity concentrated water and perform advanced treatment to produce clean raw water. The membrane-based precision salt separation unit is used to separate clean raw water into sodium chloride-rich brine and sodium sulfate-rich brine. The fractional crystallization and purification scale prevention unit includes a freeze / evaporation crystallization sub-unit for treating sodium sulfate-rich brine and an MVR evaporation crystallization sub-unit for treating sodium chloride-rich brine. The intelligent collaborative control center communicates with the water quality reconstruction unit, the membrane-based precise salt separation unit, and the fractional crystallization, purification, and scale prevention unit. The mother liquor discharge branch of the fractional crystallization and purification scale prevention unit is equipped with an online TOC monitoring probe and an online heavy metal monitoring probe. The crystallizer product discharge pipeline is equipped with an online crystal purity / whiteness monitoring probe, and the crystallizer circulation pipeline is equipped with an online turbidity monitoring probe. Each crystallizer is equipped with an integrated device for seed circulation and mother liquor purification. This device includes at least a seed induction zone, an online turbidity monitoring probe, a hydrocyclone separator, an automatic regulating valve for the mother liquor discharge branch, and a new seed replenishment metering and dosing device. The intelligent collaborative control center is configured to perform full-chain cascade regulation based on detection data from TOC, heavy metals, and crystal purity / whiteness monitoring probes, and to independently implement dynamic management of seed activity for each crystallizer based on the coupled data from the online turbidity monitoring probe and the online crystal purity / whiteness monitoring probe.

2. The fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering according to claim 1, characterized in that: The water quality reconstruction unit includes a multi-source catalytic oxidation module and a selective adsorption and fine filtration module connected in sequence. The intelligent collaborative control center is further configured to generate targeted instructions based on the type and combination relationship of the degradation signals: In response to signals of deterioration in mother liquor TOC or deterioration in crystal whiteness, instructions are generated to increase the oxidation intensity of the multi-source catalytic oxidation module or to extend its reaction residence time. In response to the heavy metal degradation signal of the mother liquor, instructions to enhance the selective adsorption and fine filtration module are generated first, and a compensatory oxidation instruction is generated simultaneously based on cascade analysis to determine when heavy metal penetration and insufficient oxidative complex breaking are correlated. In response to crystal purity degradation occurring alone, the water quality reconstruction unit is suppressed and seed activity dynamic management is triggered preferentially; in response to crystal purity degradation accompanied by TOC or whiteness degradation, organic matter penetration is determined to be a common factor and the depth adjustment of the water quality reconstruction unit is executed. When generating instructions to extend the reaction dwell time, the intelligent collaborative control center is also configured to: The increment of oxidant dosage is calculated based on the TOC deviation and whiteness deviation of each control cycle; The minimum theoretical hydraulic residence time required is determined based on the current TOC deviation and the pre-stored TOC-residence time correlation curve. When the minimum theoretical hydraulic residence time does not exceed the current maximum available hydraulic residence time of the multi-source catalytic oxidation module, an extended residence time instruction is generated and the target influent flow rate is calculated. During the execution of the extended residence time, the online flow meter data on the pipeline of the multi-source catalytic oxidation module is monitored simultaneously. When the influent flow rate is lower than the preset minimum anti-short flow threshold, the flow rate is stopped from being further reduced. When the minimum theoretical hydraulic residence time exceeds the maximum available hydraulic residence time, the option to extend the residence time is abandoned, and instead a higher oxidant increment instruction based on the organic pollution load equivalent deviation is generated.

3. The fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering according to claim 1, characterized in that: The membrane-based precision salt separation unit includes a high-pressure nanofiltration system and a secondary nanofiltration concentration device, wherein the secondary nanofiltration concentration device receives the cryogenic mother liquor from the freezing / evaporation crystallization subunit; The permeate water from the high-pressure nanofiltration system and the permeate water from the secondary nanofiltration concentration device are combined in the main pipe to form a mixed sodium chloride-rich brine. An online conductivity probe and a proportional regulating valve are installed at the point of convergence. The intelligent collaborative control center is also configured to: calculate the real-time sodium chloride concentration based on the real-time data from the online conductivity probe, combined with the conductivity-sodium chloride concentration conversion model and temperature compensation curve; and generate an opening adjustment command based on the deviation between the real-time concentration and the preset target concentration, and send it to the proportional control valve after safety constraint verification.

4. The fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering according to claim 1, characterized in that: The integrated seed circulation and mother liquor purification device for each crystallizer includes: The seed crystal induction zone is located on the crystallizer circulation pipeline; The online turbidity monitoring probe is installed on the circulation pipeline downstream of the seed induction zone; The online crystal purity / whiteness monitoring probe is installed on the crystallizer product discharge pipeline; A hydrocyclone separator is installed on the crystallizer circulation pipeline; The mother liquor discharge branch is located at the overflow outlet of the hydrocyclone separator and is equipped with the automatic regulating valve. The new seed crystal replenishment metering and dosing device is connected to the seed crystal induction region; When the intelligent collaborative control center independently implements dynamic management of seed activity for each crystallizer, it is configured as follows: Read the online turbidity value of the corresponding crystallizer and online crystal purity value Or whiteness value ; Will Maintain the lower limit of the preset seed concentration Comparison, will or Compared with the preset quality lower limit or Based on the comparison, the current operating condition is determined to belong to one of the following four categories: Operating Condition I: and or and ; Operating Condition II: and or and ; Operating Condition III: and or and ; Operating Condition IV: and or and ; Based on the determined operating condition category, the independent adjustment of the mother liquor discharge branch ratio, the new seed crystal replenishment acceleration rate, and the hydrocyclone stage efficiency is calculated and executed in a deviation-driven manner. Operating condition II is determined to be a decrease in seed crystal activity, operating condition III is determined to be an insufficient number of seed crystals, and operating condition IV is determined to be an insufficient number of both seed crystal activity and seed crystals.

5. The fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering according to claim 1, characterized in that: The intelligent collaborative control center is pre-configured with a scene mode library that includes at least an electroplating mode and a titanium dioxide mode, and is further configured as follows: Real-time acquisition of boiling point rise data B and supersaturation data S from the MVR evaporation and crystallization sub-unit; Call the weight coefficient corresponding to the current scene mode , In the electroplating mode Titanium dioxide mode Calculate the comprehensive risk value In the formula , The baseline warning threshold; when R When the value exceeds 1, an effect switching command is triggered. Before the effect switching command is executed, a command is sent in advance to the new seed replenishment metering device and the automatic regulating valve of the mother liquor discharge branch of the corresponding crystallizer to increase the new seed addition rate and temporarily reduce the mother liquor discharge split ratio.

6. The fractional crystallization and resource recovery system for high-salinity industrial wastewater engineering according to claim 1, characterized in that: The intelligent collaborative control center is also configured to: when multiple degradation signals triggering adjustment commands conflict within the same control cycle, arbitrate according to a preset priority. The first priority is product quality assurance; instructions triggered by the deterioration of mother liquor heavy metal concentration or crystal purity will be executed first. The second priority is system anti-scaling protection; the effect switching command triggered by abnormal boiling point rise or supersaturation takes precedence over the normal adjustment command. The third priority is operational economy. Under the premise of satisfying the first two priorities, the adjustment combination with the lowest overall energy consumption or chemical consumption is selected. If the flow restriction action caused by prioritizing quality or scale prevention conflicts with the economic target, the extended residence time scheme is abandoned, a more compensatory oxidant increment scheme is adopted, and the instruction to reduce the influent flow rate is removed from the final instruction set.

7. A method for fractional crystallization and resource recovery in high-salinity industrial wastewater treatment projects, applied to a fractional crystallization and resource recovery system for high-salinity industrial wastewater treatment projects as described in any one of claims 1-6, characterized in that: Including the following steps: High-salinity concentrated water is reconstructed to produce clean raw water; Clean raw water is precisely separated into sodium chloride-rich brine and sodium sulfate-rich brine using a membrane method; Sodium sulfate-rich brine was subjected to freeze / evaporation crystallization, and sodium chloride-rich brine was subjected to MVR evaporation crystallization, while maintaining seed crystal circulation during the crystallization process; The following closed-loop control steps are executed simultaneously during the crystallization process: The system can acquire data on the TOC concentration, heavy metal concentration, and purity / whiteness of the product crystals of the mother liquor online, and also acquire data on the turbidity of the circulating mother liquor in the crystallizer online. When at least one of the following factors—TOC concentration, heavy metal concentration, crystal purity, and crystal whiteness—shows a deterioration trend, a targeted instruction is generated based on the type of deterioration and its combination relationship, and feedback is used to adjust the depth of the water quality reconstruction treatment or the operating parameters of the membrane-based precise salt separation. The turbidity data is coupled with the purity / whiteness data. The operating condition category is determined based on the comparison results of turbidity and preset seed concentration maintenance lower limit and purity / whiteness and preset quality lower limit. At least one of the following is adjusted independently according to the operating condition category: mother liquor discharge branch ratio, new seed replenishment acceleration rate and hydrocyclone classification efficiency.

8. The method for fractional crystallization and resource recovery of high-salinity industrial wastewater as described in claim 7, characterized in that: The generation of targeted instructions based on degradation types and their combination relationships includes: When the TOC of the mother liquor deteriorates or the whiteness of the crystals deteriorates, the oxidation intensity of the multi-source catalytic oxidation is increased or the reaction residence time is extended. When the current maximum available residence time cannot meet the requirements, a higher compensating oxidant increment is adopted. The logic for generating the higher compensating oxidant increment is: based on the difference between the current TOC value and the concentration that can be treated at the maximum residence time and the organic pollution load equivalent deviation calculated according to the historical data association model, multiplied by the compensation gain coefficient. When heavy metal deterioration occurs in the mother liquor, selective adsorption treatment should be strengthened first, and the TOC change trend should be combined to determine whether compensatory oxidation regulation is generated simultaneously. When crystal purity deterioration occurs alone, water quality reconstruction adjustment is not triggered, but crystal activity management is adjusted first; when crystal purity deterioration is accompanied by TOC or whiteness deterioration, it is determined to be organic matter penetration and water quality reconstruction depth adjustment is performed simultaneously. When multiple deterioration trends occur within the same control cycle and the corresponding feedback control commands conflict, arbitration shall be performed according to the following priority: Adjustments triggered by deterioration in mother liquor heavy metal concentration or crystal purity will be prioritized. Next, the effect switching is performed based on the abnormal boiling point rise or supersaturation. Under the premise that the aforementioned priorities are met, select the adjustment combination with the lowest energy consumption or reagent consumption; If prioritizing quality or scale prevention necessitates flow restriction, and this flow restriction conflicts with economic objectives, then the extended residence time option should be abandoned, and a more compensatory incremental oxidant option should be adopted instead.

9. The method for fractional crystallization and resource recovery of high-salinity industrial wastewater as described in claim 7, characterized in that: Feedback adjustment of the operating parameters for the membrane-based precise salt separation includes: When the TOC concentration of the mother liquor continues to rise, increase the operating pressure of the high-pressure nanofiltration system to enhance the organic matter rejection rate, or adjust the feed flow rate or operating pressure of the secondary nanofiltration concentration unit. The conductivity of the two sodium chloride-rich brine streams after merging is acquired in real time and converted into the real-time sodium chloride concentration after temperature compensation. Based on the deviation between the real-time concentration and the target concentration, the opening of the proportional control valve at the merging point is adjusted to stabilize the concentration of the mixed brine entering the MVR evaporation and crystallization process. The independent adjustment based on operating condition category includes: When the turbidity meets the standard and the purity / whiteness decreases, it is determined that the seed crystal activity has declined. The solution is to increase the mother liquor discharge ratio, increase the new seed crystal addition rate, and improve the hydrocyclone separator classification efficiency. When the turbidity is insufficient but the purity / whiteness meets the standards, the main approach is to supplement with new seed crystals. When both are insufficient, simultaneous external discharge, supplementation, and enhanced hierarchical separation are performed. Once both parameters meet the target and remain stable for the preset period, restore each adjustment value to the baseline value and switch to steady-state monitoring.

10. The method for fractional crystallization and resource recovery of high-salinity industrial wastewater as described in claim 7, characterized in that: Also includes: Real-time monitoring of boiling point rise and supersaturation of MVR evaporation and crystallization; calculation of comprehensive risk value based on the corresponding weighting coefficients according to preset scenario modes. When the comprehensive risk value exceeds the limit and triggers the effect switching, before the effect switching is executed, the new seed crystal addition acceleration rate of the corresponding crystallizer is increased in advance and the mother liquor discharge ratio is temporarily reduced. After the effect switching action is executed for a preset short duration, the disturbance is determined based on the real-time supersaturation or boiling point rise data. If the disturbance is eliminated, the parameters of the evaporation condition and the seed crystal circulation device are restored to the reference values ​​before the effect switching. If the disturbance is not eliminated, the current effect switching state is maintained and continuous monitoring is performed.

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