Modularized ultrapure water preparation system capable of being intelligently regulated and controlled

Abstract

The invention relates to the technical field of water treatment, and discloses an intelligently controllable modularized ultrapure water preparation system, which comprises a pretreatment unit, a primary reverse osmosis system, a secondary reverse osmosis system, a terminal fine treatment system and an intelligent control unit which are sequentially connected along the water flow direction. The second-stage reverse osmosis system comprises a second-stage RO high-pressure water pump, and the terminal precision treatment system comprises an EDI system. The intelligent control unit is configured to execute an energy efficiency optimization strategy; a solute penetration and pressure response model is operated, and the water production prediction conductivity of the secondary reverse osmosis unit is calculated; and when it is judged that the working condition is the redundant working condition, the operation frequency of the second-stage RO high-pressure water pump is reduced so as to reduce mechanical energy consumption, and the operation current of the EDI system is synchronously increased according to the predicted conductivity so as to conduct electrochemical energy compensation. By constructing a coupling control and feed-forward regulation mechanism of mechanical energy and electrochemical energy, the overall operation energy consumption of the system is reduced on the premise of eliminating control lag and ensuring stable water quality of produced water.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a modular ultrapure water preparation system with intelligent controllability. Background Technology

[0002] Ultrapure water preparation systems are widely used in industries such as semiconductor manufacturing, pharmaceutical production, and power generation. Existing preparation processes typically employ a combined architecture of pretreatment, two-stage reverse osmosis (RO), and final purification to ensure that the final product water meets stringent resistivity and particle size standards.

[0003] In a typical existing technology, raw water first passes through a pretreatment unit consisting of a multi-media filter and an activated carbon filter to remove suspended solids, colloids, organic matter, and residual chlorine, thereby protecting the subsequent membrane modules. The pretreated water is then driven by a first-stage RO high-pressure water pump into the first-stage reverse osmosis system for preliminary desalination. Subsequently, it is pressurized by a second-stage RO high-pressure water pump and enters the second-stage reverse osmosis unit to further improve purity. To meet even higher water quality requirements, the second-stage reverse osmosis permeate also passes through an EDI booster pump, an ultraviolet sterilizer, and a precision filter before entering the electrodeionization (EDI) system. Finally, it undergoes deep treatment at the end through a total organic carbon (TOC) remover, a polishing mixed bed, and a terminal filter to obtain ultrapure water.

[0004] While the aforementioned multi-stage series process can achieve water purification goals in terms of hardware architecture, it still has shortcomings in actual operation and control. Existing control strategies mostly focus on the independent and stable operation of each unit. For example, the secondary RO high-pressure pump is usually set to operate at a fixed high frequency or pressure to ensure sufficient desalination rate and flux even under the worst influent conditions. This redundant design means that the system cannot automatically reduce pumping power when the influent water quality is good, resulting in a continuous waste of mechanical energy.

[0005] Furthermore, there is a lack of effective linkage and regulation mechanisms between the subsequent EDI system and the upstream reverse osmosis system. EDI systems typically employ constant current or sensor-based real-time feedback regulation modes. Reducing the operating frequency of the reverse osmosis pump to save energy leads to an increase in the conductivity of the reverse osmosis permeate, and sensor-based control inherently suffers from time lag. This lag makes it difficult for the EDI system to adjust the operating current in time to compensate for increases in ion load, easily causing fluctuations in permeate water quality or even short-term exceedances. Long-term load mismatch may also shorten the replacement cycle of consumables such as the polishing mixed bed. Therefore, how to achieve a dynamic balance between energy consumption reduction and water quality stability through optimized control strategies based on the existing hardware architecture is a problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a modular ultrapure water preparation system with intelligent controllability, which solves the problems of independent operation and control of reverse osmosis unit and electro-deionization unit in existing ultrapure water preparation processes, making it difficult for the system to achieve energy efficiency optimization while ensuring water quality stability, and the lag of traditional feedback control mechanism, which cannot cope with water quality fluctuations under dynamic operating conditions.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a modular ultrapure water preparation system with intelligent controllability, comprising a pretreatment unit, a primary reverse osmosis system, a secondary reverse osmosis system, and a final purification system connected sequentially along the water flow direction, and an intelligent control unit electrically connected to the secondary reverse osmosis system and the final purification system. The secondary reverse osmosis system includes a secondary RO high-pressure water pump for driving the water flow and a secondary reverse osmosis unit, while the final purification system includes an EDI system. The intelligent control unit is configured to execute an energy efficiency optimization strategy: acquiring the predicted conductivity of the permeate from the secondary reverse osmosis unit, adjusting the operating frequency of the secondary RO high-pressure water pump based on the predicted conductivity, and synchronously adjusting the operating current of the EDI system based on the predicted conductivity.

[0009] The pretreatment unit and the first-stage reverse osmosis system include, in sequence along the water flow direction, a raw water tank, a raw water pump, a multi-media filter, an activated carbon filter, a filtered water tank, a first-stage RO booster pump, a security filter, a first-stage RO high-pressure pump, a first-stage reverse osmosis system, and a first-stage RO water tank; the outlet of the first-stage RO water tank is connected to the inlet of the second-stage RO high-pressure pump via a second-stage RO booster pump. The terminal fine treatment system includes, in sequence along the water flow direction, an EDI booster pump, an ultraviolet sterilizer, a precision filter, an EDI system, a pure water tank, a pure water pump, a total organic carbon remover, a polishing mixed bed, and a terminal filter; the permeate outlet of the second-stage reverse osmosis unit is connected to the inlet of the EDI booster pump via the second-stage RO water tank. The system also includes a first conductivity sensor installed on the permeate side of the first-stage reverse osmosis system, a frequency feedback device installed at the second-stage RO high-pressure pump, and a pressure sensor installed on the inlet side of the second-stage reverse osmosis unit. The intelligent control unit is connected to the above sensors and feedback devices to obtain the reference conductivity of the first-stage RO permeate, the real-time operating frequency of the second-stage RO high-pressure pump, and the inlet pressure of the second-stage reverse osmosis unit.

[0010] The intelligent control unit is configured to run a solute permeation and pressure response model, which is based on the dilution effect mechanism of the reverse osmosis membrane and is used to calculate the predicted conductivity of the permeate. The calculation logic follows these rules:

[0011] The predicted conductivity of the permeate is positively correlated with the baseline conductivity of the first-stage RO permeate and the inherent permeability coefficient of the second-stage reverse osmosis membrane module, and negatively correlated with the power of the pressure response exponent of the operating pressure of the second-stage RO high-pressure water pump, and is corrected by a temperature correction factor. The pressure response exponent is used to correct for the impact of membrane compaction on flux under non-ideal conditions.

[0012] Based on the aforementioned prediction model, the intelligent control unit executes operating condition determination and adjustment logic. The system compares the predicted conductivity of the permeate with the EDI feed water safety threshold. The EDI feed water safety threshold is a safety boundary set based on the physicochemical characteristics of the electro-deionization module. This boundary is based on the mechanism that if the feed water conductivity exceeds this threshold, the resin bed will rapidly fail and a breakthrough phenomenon will occur. When the predicted conductivity of the permeate is less than a first preset proportion of the EDI feed water safety threshold, the system determines it to be in a redundant operating condition. The intelligent control unit uses a perturbation observation method to perform a step-wise reduction in the operating frequency of the secondary RO high-pressure water pump to reduce mechanical energy consumption.

[0013] To ensure system operational safety, the intelligent control unit is also equipped with a safety interlock forced reset mechanism and optimal maintenance logic. When the predicted conductivity of the permeate exceeds the EDI inlet water safety threshold, it is determined to be a risky operating condition. The intelligent control unit interrupts the energy-saving optimization process and forcibly resets the operating frequency of the secondary RO high-pressure water pump to a safe frequency, utilizing the dilution effect under high pressure to reduce the permeate conductivity. When the predicted conductivity of the permeate is between the first and second preset proportions of the EDI inlet water safety threshold, it is determined to be an optimal operating condition. The intelligent control unit controls the secondary RO high-pressure water pump to maintain its current operating frequency.

[0014] While reducing mechanical energy consumption, the intelligent control unit performs feedforward compensation control on the operating current of the EDI system. This adjustment logic follows Faraday's law of electrolysis, establishing a linear mapping relationship between the influent load and the operating current. The specific calculation logic is as follows:

[0015] First, the difference between the predicted conductivity of the permeate or the real-time measured conductivity of the influent and the conductivity of the ideal pure water is calculated. This difference is then combined with the real-time flow rate and pre-calibrated conductivity and current conversion coefficients to calculate the dynamic current component used to remove dynamic ion load. This dynamic current component is then superimposed with the baseline current component used to maintain resin regeneration to obtain the final output current setpoint. When the operating frequency of the secondary RO high-pressure pump decreases, leading to an increase in the predicted conductivity of the permeate, the calculated current setpoint increases synchronously. The intelligent control unit controls the EDI system to increase its operating current, enhancing the DC electric field intensity perpendicular to the water flow direction, accelerating ion migration to the concentrate chamber, and using electrochemical energy to compensate for water quality fluctuations caused by a decrease in mechanical energy.

[0016] In addition, the pretreatment unit also includes a chemical dosing device and a heat exchanger. The chemical dosing device is located upstream of the multi-media filter and is used to proportionally feedforward add scale inhibitors or bactericides based on the flow signal. The heat exchanger is located downstream of the raw water pump and is used to regulate the water temperature entering the first-stage reverse osmosis system, reducing the impact of temperature fluctuations on the accuracy of the reverse osmosis membrane flux and conductivity prediction model.

[0017] This invention utilizes the characteristic that the mechanical energy consumption of a secondary reverse osmosis pump decreases with the cube of the frequency, and the characteristic that the electrochemical energy consumption of an EDI pump increases linearly with the load, to achieve cross-unit energy coupling control. While ensuring that the product water quality meets standards, the system can maintain operation at the lowest total energy consumption. Furthermore, feedforward control based on a predictive model eliminates the hysteresis of traditional feedback control, improving the system's responsiveness to water quality fluctuations.

[0018] In summary, the present invention has at least one of the following beneficial technical effects:

[0019] 1. This invention utilizes an intelligent control unit and an algorithm model to evaluate operating conditions in real time. When water quality is redundant, it reduces the frequency of the high-energy-consuming secondary RO high-pressure water pump, while simultaneously calculating and increasing the low-energy-consuming EDI current for electrochemical compensation. This energy scheduling method breaks the limitation of independent operation of each treatment unit, effectively reducing the overall operating cost of the system while ensuring that the produced water quality meets standards.

[0020] 2. This invention calculates the changing trend of the produced water quality in advance based on online monitoring of pressure and conductivity data, and adjusts the operating parameters before the fluctuations actually reach the terminal fine treatment system. This control mechanism eliminates the lag in traditional feedback regulation and avoids the risk of instantaneous water quality exceeding standards, thereby achieving the preparation of ultrapure water with high purity and high stability.

[0021] 3. This invention introduces a heat exchanger to ensure the reverse osmosis membrane operates within its optimal temperature range, improving membrane flux and the accuracy of predictive model calculations. Combined with precise chemical dosing and the setting of a safe threshold for EDI feed water, it effectively prevents membrane surface scaling and EDI resin bed penetration failure. These measures collectively reduce system maintenance frequency and ensure long-term stable operation of the equipment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of an ultrapure water preparation system according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the method flow of the present invention;

[0024] Figure 3 This is a schematic diagram of the stepwise adjustment process of the operating frequency of the secondary reverse osmosis high-pressure water pump over time in one embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram illustrating the reduction in mechanical energy consumption of the RO pump, the compensatory increase in electrochemical energy consumption of EDI, and the net decrease in total system energy consumption in one embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram illustrating the water quality response in one embodiment of the present invention, where the resistivity of the terminal product water remains stable despite fluctuations in the conductivity of the intermediate product water due to energy-saving adjustments. Detailed Implementation

[0027] The following is in conjunction with the appendix Figure 1 - Appendix Figure 5 The present invention will be further described in detail below.

[0028] See attached document Figure 1 This invention provides a modular ultrapure water preparation system with intelligent controllability. The system's overall architecture includes a pretreatment unit, a primary reverse osmosis system, a secondary reverse osmosis system, and a terminal purification system, all connected sequentially along the water flow direction. Furthermore, the system is equipped with an intelligent control unit, which establishes electrical or signal connections with the electrical actuators and sensing elements in each of the aforementioned systems or units to achieve coordinated control of the entire system.

[0029] The pretreatment unit and the first-stage reverse osmosis system are mainly used for the pretreatment and primary desalination of raw water. The specific hardware connections are as follows: Raw water is piped into the raw water tank, and the outlet of the raw water tank is connected to the raw water pump. A heat exchanger is installed on the pipeline downstream of the raw water pump to regulate the water temperature entering the subsequent systems. A chemical dosing device is located upstream of the multi-media filter to add water treatment agents such as scale inhibitors or bactericides into the pipeline. The raw water is pumped sequentially through the multi-media filter and the activated carbon filter to remove suspended particles and organic contaminants before entering the filtered water tank. The outlet of the filtered water tank is sequentially connected to the first-stage RO booster pump, the security filter, and the first-stage RO high-pressure pump. The first-stage RO high-pressure pump drives the water flow into the first-stage reverse osmosis system for desalination treatment. The permeate side of the first-stage reverse osmosis system is connected to the first-stage RO tank. In addition, a first conductivity sensor is installed on the permeate side of the first-stage reverse osmosis system to collect the reference conductivity of the first-stage RO permeate.

[0030] The two-stage reverse osmosis system is used to perform two-stage desalination and energy efficiency optimization control. The outlet of the first-stage RO tank is connected to the inlet of the second-stage RO high-pressure pump via a second-stage RO booster pump. The second-stage RO high-pressure pump is connected to the second-stage reverse osmosis unit, and the product water side of the second-stage reverse osmosis unit is connected to the second-stage RO tank. To achieve intelligent control, a frequency feedback device is installed at the second-stage RO high-pressure pump to provide feedback on the pump's real-time operating frequency; a pressure sensor is installed on the inlet side of the second-stage reverse osmosis unit to collect the inlet water pressure.

[0031] The terminal purification system is used for deep desalination and final purification to ensure that the produced water meets ultrapure water standards. The outlet of the secondary RO tank is connected to an EDI booster pump. Downstream of the EDI booster pump, a UV sterilizer and a precision filter are connected in series. The outlet of the precision filter is connected to the EDI system, and the product water side of the EDI system is connected to a pure water tank. The outlet of the pure water tank is connected to a pure water pump, and downstream of the pure water pump, a total organic carbon remover, a polishing mixed bed, and a terminal filter are connected in series, ultimately outputting ultrapure water at the user's point of use.

[0032] The intelligent control unit, as the core of the system, is connected to the first conductivity sensor, frequency feedback unit, and pressure sensor. The intelligent control unit is configured to execute an energy efficiency optimization strategy: it calculates the predicted conductivity of the permeate based on the collected baseline conductivity of the first-stage RO permeate and the inlet pressure, and dynamically adjusts the operating frequency of the second-stage RO high-pressure pump accordingly. Simultaneously, it synchronously adjusts the operating current of the EDI system based on the predicted permeate conductivity, achieving synergistic optimization of mechanical and electrochemical energy.

[0033] See attached document Figure 2 This invention provides a modular ultrapure water preparation method with intelligent controllability, which is executed based on the aforementioned system and includes the following steps:

[0034] S10, Pretreatment and Temperature Control. Raw water is introduced into the pretreatment unit. The raw water pump is started, and the water temperature is stabilized within a preset temperature range suitable for reverse osmosis membrane operation using the heat exchanger downstream of it. Chemicals are injected through a chemical dosing device located upstream of the multi-media filter to inhibit scaling or biological growth. The raw water then undergoes filtration treatment through the multi-media filter and activated carbon filter, and is stored in the filtered water tank.

[0035] S20, First-stage reverse osmosis desalination and baseline parameter acquisition. The first-stage RO booster pump and the first-stage RO high-pressure pump are started to send water into the first-stage reverse osmosis system for initial desalination. The permeate enters the first-stage RO tank. During this process, the baseline conductivity of the first-stage RO permeate is collected in real time using a first conductivity sensor, serving as an input parameter for subsequent energy efficiency optimization.

[0036] S30, Secondary Reverse Osmosis Energy Efficiency Optimization Control. Water is drawn from the primary RO tank, pressurized by the secondary RO booster pump and secondary RO high-pressure pump, and then sent to the secondary reverse osmosis unit. Based on data from the first conductivity sensor, pressure sensor, and frequency feedback unit, the intelligent control unit constructs a solute permeation and pressure response model and calculates the predicted conductivity of the permeate. According to the ratio of this predicted conductivity to the EDI feed water safety threshold, the intelligent control unit determines the current operating condition (redundant, optimal, or risky) and dynamically adjusts the operating frequency of the secondary RO high-pressure pump accordingly, reducing pumping energy consumption while ensuring the permeate water quality meets requirements. The secondary permeate is stored in the secondary RO tank.

[0037] S40, Terminal Fine Treatment and EDI Load Coordination Compensation. An EDI booster pump delivers water to an ultraviolet sterilizer and a precision filter. The water then flows into the EDI system for deep deionization. During this stage, the intelligent control unit calculates the EDI influent load based on the predicted conductivity of the permeate obtained in S30 and simultaneously adjusts the operating current of the EDI system. When the frequency reduction of the secondary RO high-pressure pump causes fluctuations in the influent conductivity, the intelligent control unit increases the EDI current, using electrochemical energy to compensate for the decrease in mechanical energy. The EDI permeate is finally pressurized by a pure water pump and sequentially passes through a total organic carbon remover, a polishing mixed bed, and a terminal filter before being output from the user's point of use.

[0038] The above steps will be described in detail below with reference to specific embodiments and accompanying drawings:

[0039] The multi-level physical filtering mechanism in step S10 specifically includes the following sub-steps:

[0040] S101, Raw Water Buffering and Flow Stabilization. Raw water is connected to a raw water tank, utilizing its large volume to reduce pressure fluctuations and flow instability in the upstream water supply network. A level sensor is installed inside the raw water tank to monitor the water level in real time and transmit the signal to the intelligent control unit. The intelligent control unit has a preset low-level protection threshold, typically set to 10% to 15% of the effective height of the raw water tank. When the detected level is above this threshold, the intelligent control unit allows the raw water pump to start; when the level is below this threshold, it forces a shutdown to prevent pump cavitation during dry running. The raw water pump uses variable frequency control, dynamically adjusting the motor speed to output a matching head based on the constant influent flow requirements set by subsequent processes. This head is designed to overcome the total head loss of the multi-media filter and activated carbon filter under maximum sludge accumulation conditions.

[0041] S102, deep multi-media cascaded interception. Raw water passes through the filter media layer of the multi-media filter from top to bottom under pressure. The multi-media filter achieves natural stratification by using filter media with different densities and particle sizes. From top to bottom, it is laid with anthracite filter media with lower density but larger particle size, quartz sand filter media with medium density and medium particle size, and magnetite or garnet filter media with higher density but smaller particle size.

[0042] In this embodiment, the effective particle size range of the anthracite filter media is 0.8 to 1.2 mm, mainly used to intercept large suspended particles and extend the operating cycle; the effective particle size range of the quartz sand filter media is 0.5 to 0.8 mm, used to remove medium colloids; and the effective particle size range of the heavy filter media is 0.25 to 0.5 mm, used to form a fine barrier at the bottom of the filter bed. This gradation structure utilizes the principle of deep filtration, allowing impurities not only to be trapped on the surface of the filter media but also to penetrate deep into the pores inside the filter bed, thereby significantly improving the dirt-holding capacity. The system strictly controls the filtration flow rate during operation within the range of 8 to 12 m / h to ensure sufficient contact and settling time between the raw water and the filter media, ensuring that the pollution index of the effluent is consistently below 5, meeting the reverse osmosis feed water requirements.

[0043] S103, adsorption purification and oxidation-reduction dechlorination. The effluent after S102 treatment enters the activated carbon filter. The activated carbon filter uses high-quality fruit shell activated carbon with an iodine value greater than 900 mg / g, which utilizes the van der Waals forces generated by the dense micropores on its surface to physically adsorb small molecule organic matter, pigments and odor substances in the water.

[0044] More importantly, activated carbon plays a chemical catalytic reduction role in this process. When influent containing residual chlorine comes into contact with the surface of activated carbon, the activated carbon acts as a reducing agent, reducing highly oxidizing hypochlorous acid or hypochlorite ions to chemically stable chloride ions, while the surface of the activated carbon is oxidized to form surface oxides or carbon dioxide. This process completely eliminates oxidizing substances in the water, preventing them from causing irreversible oxidative degradation to the subsequent polyamide reverse osmosis membrane.

[0045] S104, Product Water Buffer and Conditioning. Water treated by the activated carbon filter enters the filter tank for temporary storage. The filter tank acts as an intermediate buffer between the pretreatment unit and the reverse osmosis unit, balancing the instantaneous flow differences between the upstream and downstream equipment. The design residence time of the filter tank is typically set to 15 to 30 minutes. This residence time allows sufficient time for the tiny air bubbles dissolved in the water during pressure filtration to rise and overflow to the surface, thereby eliminating air resistance in the water and preventing air bubbles from entering the subsequent high-pressure pump and causing cavitation or vibration.

[0046] S105, Real-time acquisition and deviation calculation of temperature data. The pretreated water, after processing in S104, enters the heat exchanger. High-precision temperature sensors are installed at the inlet and outlet of the heat exchanger to collect inlet and outlet water temperature data in real time. The intelligent control unit reads the temperature data at a set sampling frequency and compares the outlet water temperature with the system's preset target temperature value in real time to calculate the temperature deviation. In this embodiment, to match the optimal physical performance of the polyamide composite reverse osmosis membrane, the target temperature value is strictly set to 25 degrees Celsius, and the allowable control dead zone range is ±2 degrees Celsius.

[0047] S106, Dynamic adjustment of the heat exchange medium based on heat load demand. The intelligent control unit dynamically adjusts the operating status of the heat exchanger based on the temperature deviation value calculated by S105. The heat exchanger adopts a plate heat exchange structure, with pretreated water to be treated introduced on the process side, and a cold / hot regulating medium pipeline connected to the heat medium side. When the inlet water temperature is below 23 degrees Celsius, the intelligent control unit determines it to be a low-temperature condition and outputs a signal to open the electric regulating valve on the heat medium side, introducing steam or hot water; when the inlet water temperature is above 27 degrees Celsius, cooling water is introduced.

[0048] At this point, the intelligent control unit operates a proportional-integral-derivative closed-loop control algorithm. The intelligent control unit uses the temperature deviation as an input signal, rapidly responding to the deviation through the proportional element, eliminating steady-state error through the integral element, and predicting the temperature change trend through the derivative element. The calculated control quantity is converted into a current or voltage signal, driving the electric regulating valve to change the valve core opening. By changing the flow rate of the medium entering the heat exchanger's heat medium side, the convective heat transfer coefficient and average temperature difference of the heat exchange surface are directly changed, thereby precisely controlling the heat transfer rate until the outlet water temperature stabilizes near the target value.

[0049] S107, Membrane flux stabilization and energy consumption suppression. Closed-loop regulation in S106 ensures a constant water temperature entering the reverse osmosis system. This step is based on the physical rheological properties of water, utilizing a constant temperature environment to eliminate the impact of water dynamic viscosity fluctuations on the reverse osmosis process.

[0050] The dynamic viscosity of water is a key limiting factor for the permeability of reverse osmosis membranes. According to fluid mechanics principles, the viscosity of water has a non-linear inverse relationship with temperature. Within the normal temperature range, the dynamic viscosity of water increases by approximately 3% for every 1 degree Celsius decrease in temperature. This increase in viscosity means increased frictional resistance for water molecules passing through the pores of the reverse osmosis membrane. Without temperature control, in low-temperature winter conditions, to maintain a constant permeate flow rate (i.e., membrane flux), the first-stage RO high-pressure pump must significantly increase its output pressure to overcome the increased viscous resistance, leading to a significant increase in system power consumption. Simultaneously, a constant 25-degree Celsius environment prevents microscopic pore deformation of the reverse osmosis membrane material due to frequent thermal expansion and contraction, thus ensuring the long-term stability of the desalination rate. Regarding the specific selection of the heat exchanger's plate corrugated structure, those skilled in the art can choose common industrial standard parts based on the system's pressure rating, which will not be elaborated upon here.

[0051] S108, Flow-following proportional dosing control. The chemical dosing device employs a proportional feedback control mode based on the influent flow rate. An electromagnetic flowmeter is installed in the upstream pipeline of the chemical dosing device to monitor the instantaneous flow rate of the pretreated water entering the reverse osmosis system in real time. The intelligent control unit receives this flow signal and, according to the preset dosing ratio coefficient, changes the injection flow rate of the chemical solution by linearly adjusting the stroke frequency of the metering pump motor. This control logic establishes a feedforward control mechanism to ensure that the concentration of chemical reagents in the water is dynamically maintained within the set effective range regardless of fluctuations in the influent flow rate.

[0052] S109, Lattice Distortion Scale Inhibition Protection. The scale inhibitor dosing unit injects a specialized organophosphonate or polycarboxylic acid scale inhibitor into the water. This step utilizes the "threshold effect" principle of scale inhibitors, meaning that only a trace amount of the agent, far below the stoichiometric ratio, needs to be added to the water to alter the surface charge characteristics of the microcrystals through adsorption. The functional groups of the scale inhibitor molecules adsorb onto the surface of tiny inorganic salt crystal nuclei, interfering with the normal arrangement of the inorganic salt crystals and causing lattice distortion. Simultaneously, the dispersion effect of the polymer keeps the sparingly soluble salt particles in suspension, thereby preventing the formation of a dense scale layer on the reverse osmosis membrane surface by sparingly soluble salts such as calcium carbonate, calcium sulfate, and silica.

[0053] The dosing flow rate of the scale inhibitor metering pump needs to be accurately calculated, and its control model follows the formula below:

[0054] ;

[0055] in, This represents the set flow rate of the metering pump, expressed in liters per hour. This represents the influent flow rate measured by the electromagnetic flow meter, in cubic meters per hour. This represents the preset target dosing concentration, expressed in mg / L. This value is usually determined based on the Langerile saturation index in the raw water quality analysis report, and the range is typically set to 2 to 4 mg / L. This represents the density of the original drug solution, expressed in grams per cubic centimeter. The concentration represents the mass percentage of the original drug solution and is a dimensionless value. In this embodiment, the concentration value is selected from 10% to 30%.

[0056] S110 represents the deep reduction and elimination of oxidizing substances. Although the pre-activated carbon filter has removed most of the residual chlorine, a reducing agent dosing unit is configured as a secondary safety barrier to prevent residual chlorine leakage due to activated carbon failure or penetration. This unit typically adds sodium bisulfite solution. An oxidation-reduction potential sensor is installed on the pipeline after the chemical dosing point to monitor the oxidizing state of the water in real time.

[0057] The intelligent control unit adjusts the dosage of the reducing agent based on feedback values ​​from the oxidation-reduction potential sensor. The oxidation-reduction potential value is positively correlated with the concentration of oxidants (such as residual chlorine) in the water. In this embodiment, the intelligent control unit presets a safe potential threshold, ranging from 150 mV to 250 mV. When the monitored potential value exceeds this safe potential threshold, the system determines that there is a risk of residual chlorine penetration in the water, and the intelligent control unit automatically starts or increases the frequency of the reducing agent metering pump. Utilizing the strong reducing properties of sodium bisulfite, the oxidizing hypochlorous acid is reduced to harmless chloride ions in a very short time, ensuring that the residual chlorine content in the feed water entering the reverse osmosis membrane module is strictly below 0.1 mg / L, preventing the desalination layer of the polyamide composite membrane from being oxidized and degraded.

[0058] The step-by-step pressurization desalination mechanism in step S20 specifically includes the following sub-steps:

[0059] S201, Low-Pressure Pre-pressurization and Precision Interception. The pretreated water first enters the primary RO booster pump. This pump, as the first stage of the cascade pressurization, is typically a low-head, high-flow centrifugal pump, its main function being to provide a base pressure of 0.2 to 0.4 MPa. This base pressure has a dual function: firstly, it overcomes the filter element resistance of the security filter; secondly, it meets the net positive suction head requirements of the subsequent high-pressure pump, preventing cavitation caused by bubble bursting at the high-pressure pump impeller inlet due to excessively low pressure. The security filter is equipped with a 5-micron melt-blown polypropylene filter element, serving as the final physical barrier to intercept any trace particles, activated carbon powder, or microbial debris that may leak from the pretreatment system.

[0060] S202, high-pressure power drive. Water, after being filtered to remove particles by the security filter, enters the first-stage RO high-pressure water pump. This pump, as the core power source of the system, is a vertical multi-stage centrifugal pump and operates under the control of a frequency converter. The first-stage RO high-pressure water pump significantly increases the inlet water pressure to the operating pressure range of 1.0 to 1.5 MPa. This pressure range is set through rigorous calculations and must be significantly higher than the maximum natural osmotic pressure of the raw water during the concentration process, thereby offsetting osmotic resistance and providing a continuous net driving force for the transmembrane migration of water molecules.

[0061] S203, reverse osmosis and cross-flow separation. High-pressure water flows into the first-stage reverse osmosis system. The system adopts a "cross-flow filtration" operating mode, that is, the direction of the feed water flow is perpendicular to the direction of the permeate flow. The high-speed flow of feed water washes the membrane surface, and the shear force generated carries away the high concentration of salt accumulated on the membrane surface, thereby effectively suppressing the "concentration polarization" phenomenon.

[0062] Under pressure, water molecules permeate through a semipermeable membrane following a dissolution-diffusion model. The relationship between permeate flux (the amount of water produced per unit membrane area) and driving pressure follows the physical formula:

[0063] ;

[0064] in, Represents water flux, measured in liters per square meter per hour; This represents the water permeability coefficient of the membrane, which is closely related to the water temperature controlled in step S10. Represents the transmembrane pressure difference, which is the difference between the average pressure on the feed water side and the back pressure on the product water side, and the unit is megapascals; This represents the osmotic pressure difference between the solutions on both sides of the membrane, measured in megapascals (MPa).

[0065] The retained inorganic salts, organic matter, and microorganisms accumulate on the concentrate side. The system strictly controls the recovery rate of the first-stage reverse osmosis system within the range of 50% to 75% by adjusting the opening of the concentrate discharge valve. This recovery rate range ensures sufficient flow velocity on the concentrate side while guaranteeing permeate efficiency, allowing for timely removal of retained impurities and maintaining long-term stable operation of the membrane modules.

[0066] S204, Conductivity Data Acquisition and Temperature Compensation. An online conductivity analyzer is installed on the permeate pipeline of the first-stage reverse osmosis system. This analyzer uses a dual-electrode or quad-electrode contact sensor, with an electrode constant preferably between 0.01 and 0.1 cm reciprocal to accommodate the extremely low ion concentration in the reverse osmosis permeate and ensure measurement accuracy. The sensor measures the resistivity of the water in real time and converts its reciprocal into a conductivity value.

[0067] Because the conductivity of aqueous solutions is significantly affected by temperature, the physical mechanism lies in the fact that increased temperature intensifies the thermal motion of water molecules, reduces solution viscosity, and thus increases ion mobility. Unprocessed raw data cannot objectively reflect the purity of the water. Therefore, the analyzer uses a temperature compensation algorithm to uniformly convert the measured conductivity to a reference conductivity at 25 degrees Celsius. The conversion process follows the following linear temperature compensation formula:

[0068] ;

[0069] in, The baseline conductivity representing the permeate from the first stage of reverse osmosis is expressed in microsiemens per centimeter. This represents the sensor's position at the current water temperature. The actual conductivity measured below is expressed in microsiemens per centimeter. The measured water temperature is in degrees Celsius. This data is collected synchronously by a platinum resistance temperature probe integrated into the conductivity sensor. This represents the temperature compensation coefficient, which is set to 0.02 to 0.025 for the water quality characteristics of the first-stage reverse osmosis permeate. After compensation... It is transmitted to the central intelligent control unit as the first dimension input variable of the subsequent prediction model.

[0070] S205, Trace detection of total organic carbon. An online total organic carbon analyzer is installed on the pipeline bypass downstream of the conductivity detection point to monitor the residual organic matter in the primary reverse osmosis permeate. This analyzer uses the "UV oxidation-conductivity difference" detection principle. The water sample is pumped between two conductivity sensors connected in series. After the background conductivity is measured by the first sensor, the water sample flows through a reaction chamber with a built-in 185 nm wavelength UV lamp.

[0071] Under the high-energy radiation of short-wave ultraviolet light, water molecules are photolyzed to produce highly oxidizing hydroxyl radicals. These radicals rapidly oxidize and decompose trace organic matter in the water into carbon dioxide. Carbon dioxide dissolves in water to form carbonate or bicarbonate ions, leading to increased conductivity of the water. A second sensor measures the conductivity of the oxidized water sample. The analyzer's internal processor calculates the difference in conductivity measured by the two sensors. This difference is strictly proportional to the organic carbon content in the water sample. Based on this, the total organic carbon concentration is calculated. This data serves as the second-dimensional input variable for subsequent predictive models, used to monitor the integrity of the membrane module and the efficiency of organic matter removal.

[0072] S206, Signal Conversion and Digital Transmission. Sensors distributed at key nodes of the first-stage reverse osmosis system (including conductivity meters, total organic carbon analyzers, flow meters, and pressure transmitters) convert the collected physical quantities into standard 4-20 mA analog current signals. This analog signal is transmitted via shielded twisted-pair cable to the analog input module of the programmable logic controller (PLC) in the central intelligent control unit. This module has a built-in 12-bit or higher precision analog-to-digital converter (ADC) that discretizes the continuously changing analog electrical signal into digital quantities at a set sampling frequency (e.g., once every 100 milliseconds). For some intelligent instruments supporting digital communication, the system directly reads the floating-point values ​​of internal registers via an industrial fieldbus, avoiding signal attenuation and accuracy loss during analog transmission.

[0073] S207, Digital Filtering and Noise Reduction Processing. Due to electromagnetic interference and fluid pulsation caused by pump vibration in industrial settings, the raw sampling data often contains high-frequency random noise. To obtain smooth data that accurately reflects the process trend, the intelligent control unit performs a digital filtering algorithm on the collected time-series data. In this embodiment, a first-order hysteresis filtering algorithm is used to preprocess the conductivity and total organic carbon data. The filtering process follows the following difference equation:

[0074] ;

[0075] in, Representing the The output value after sampling and filtering; Representing the The original measurement value obtained from the second sampling; Representing the The filtered output value; This represents the filter coefficient, with a value ranging from 0 to 1. This coefficient characterizes the weight of the data update. The smaller the value, the greater the filter's "inertia," resulting in stronger noise suppression, but also a more pronounced hysteresis in response to signal changes. Given the relatively slow changes in water quality during reverse osmosis, a balance must be struck between noise reduction effectiveness and response speed. The value is preferably set to 0.1 to 0.3.

[0076] S208, real-time water quality status matrix construction. After filtering, the data for each dimension are synchronously mapped into the system's data register. The intelligent control unit uses the same timestamp... By combining multiple key state parameters, a multidimensional feature vector, namely the real-time water quality state matrix, is constructed. This matrix serves as the fundamental input unit for subsequent inference calculations in the neural network model, and its mathematical expression is as follows:

[0077] ;

[0078] in, Representative moment The first-stage reverse osmosis permeate reference conductivity; Representative moment Total organic carbon concentration in primary reverse osmosis permeate; Representative moment The outlet pressure of the first-stage high-pressure pump; Representative moment The first-stage reverse osmosis permeate flow rate; Representative moment The system water temperature; This represents the matrix transpose symbol.

[0079] This step enables a standardized mapping of water quality parameters from the physical world to a data model in the digital world, ensuring the synchronization of input data in the time dimension and the integrity in the spatial dimension.

[0080] The EDI safety threshold definition and water quality prediction and status determination mechanism in step S30 of the second-stage reverse osmosis energy efficiency optimization based on safety thresholds specifically include the following sub-steps:

[0081] S301, Definition of EDI Inlet Water Safety Threshold. The intelligent control unit's storage unit contains a preset EDI inlet water safety threshold, a critical safety boundary set based on the physicochemical characteristics of the electro-deionization module. The electro-deionization module is filled with cation and anion exchange resins, and ion migration is driven by a DC electric field. If the inlet water conductivity exceeds this threshold, a series of physical damages will occur:

[0082] First, a high ion load will exceed the resin's exchange and regeneration rate, leading to rapid resin bed failure, i.e., "penetration." Second, excessively high ion concentrations will reduce the resistance of the desalination chamber, causing an abnormal increase in operating current, leading to overheating or even burnout of the electrode plates. Finally, calcium and magnesium ions in the concentrate chamber easily form scale at the alkaline interface, clogging the membrane channels. In this embodiment, based on the parameters of the selected industrial-grade electro-deionization module, the EDI feed water safety threshold is set as follows:

[0083] ;

[0084] This value serves as a mandatory judgment condition in the system control logic, ensuring that the water quality entering the electro-deionization module remains within a safe range regardless of how the system adjusts its energy-saving measures.

[0085] S302, based on operating conditions, predicts permeate water quality. The intelligent control unit reads in real time the conductivity of the first-stage reverse osmosis permeate, the current system water temperature, and the current set pressure of the second-stage high-pressure pump. The system uses a built-in "solute permeation and pressure response model" to calculate the predicted conductivity of the permeate after second-stage reverse osmosis treatment under the current operating conditions.

[0086] This prediction model is based on the "dilution effect" mechanism of reverse osmosis membranes: In the reverse osmosis process, the amount of water molecules permeating (water flux) is directly proportional to the net driving pressure, while the amount of dissolved salts permeating (salt flux) mainly depends on the concentration difference across the membrane and remains essentially constant when the feed water concentration is fixed. Therefore, increasing the operating pressure increases the total amount of permeate, while the total amount of permeated salts does not change significantly. This results in more permeate "diluting" the permeated salts, leading to a decrease in permeate conductivity. This physical process is quantified by the following conductivity prediction formula:

[0087] ;

[0088] in, This represents the predicted conductivity of the second-stage reverse osmosis permeate, expressed in microsiemens per centimeter. The baseline conductivity of the first-stage reverse osmosis permeate, measured in real time, is expressed in microsiemens per centimeter. The operating pressure (inlet water pressure) of the secondary high-pressure pump is represented by megapascals (MPa). The inherent permeability coefficient of the secondary reverse osmosis membrane module is obtained by fitting measured data during the system commissioning phase. The pressure response index, ranging from 0.9 to 1.1, corrects for the effect of membrane compaction on flux under non-ideal conditions. This represents the temperature correction factor, with a value ranging from 1.03 to 1.05, used to correct for the effect of temperature changes on membrane permeability. This represents the real-time water temperature, expressed in degrees Celsius.

[0089] S303, Operating Status Determination and Logic Branch. The intelligent control unit will calculate the predicted conductivity. With the preset EDI inlet water safety threshold Compare the data and determine the current operating status accordingly: If Greater than The condition is classified as a "risk condition," indicating that the current pressure is insufficient to produce qualified influent, and the system needs to immediately increase the operating frequency of the secondary high-pressure pump.

[0090] like Less than When the pressure reaches 85% (the first preset ratio), it is determined to be a "redundant condition," indicating that the current produced water quality far exceeds the influent requirements, and there is obvious pressure excess and energy waste. The system enters the energy efficiency optimization mode and attempts to reduce the pressure of the secondary high-pressure pump.

[0091] like In If the energy consumption is between 85% and 95%, it is considered the "optimal operating condition," indicating that the system has minimized energy consumption while ensuring safety and maintaining the current operating parameters unchanged.

[0092] S304, Step-by-Step Energy Efficiency Optimization and Frequency Reduction Execution. When the operating status is determined to be "redundant condition" by step S303, the intelligent control unit activates the energy-saving mode. Addressing the non-linear coupling relationship between reverse osmosis system pressure and product water quality, this mode employs a "perturbation observation method" to progressively reduce the operating frequency of the secondary high-pressure pump, approaching the minimum system energy consumption point through a continuous "trial-and-error" process.

[0093] The intelligent control unit sends frequency adjustment commands to the frequency inverter, specifying the step size for each adjustment. The frequency is set to 0.5 to 1.0 Hz. After performing a frequency reduction operation, the system enters a waiting state with a waiting time set to 30 to 60 seconds, allowing sufficient time for the system to overcome fluid inertia and for the pipeline pressure and product water quality to reach a new steady state. After each adjustment cycle, the system recalculates the predicted conductivity. .like Still below the EDI influent safety threshold If the frequency is 90% or higher than the minimum operating frequency specified by the pump manufacturer (typically 30 Hz to 35 Hz), the system will continue with the next round of frequency reduction. This optimization process follows the iterative control formula:

[0094] ;

[0095] in, The inverter's set frequency for the next moment, measured in Hertz; The set frequency represents the current moment; This represents a fixed frequency adjustment step size; This is a sign function used to determine the adjustment direction:

[0096] Output 1 (perform frequency reduction) when the difference between the target value and the predicted value is positive, and output -1 (perform frequency increase) otherwise. The safety margin coefficient is set to 0.9, meaning the goal is to control the conductivity of the produced water at 90% of the safety threshold.

[0097] Through this logic, the system reduces the shaft power of the high-pressure pump while allowing the conductivity of the produced water to increase moderately within a safe range, thus minimizing mechanical energy consumption.

[0098] S305, Safety Interlock and Fuse Protection Mechanism. To prevent excessive levels of permeable water due to sudden changes in raw water quality or model prediction errors, the intelligent control unit has a built-in high-priority safety interlock and fuse protection mechanism. This mechanism is immediately triggered when one of the following two conditions occurs:

[0099] First, when the reference conductivity of the first-stage reverse osmosis permeate is... There are violent fluctuations, and the rate of change exceeds the set maximum allowable slope (e.g., a change of more than 5 microsiemens / cm per minute).

[0100] Second, predict conductivity. Instantly approaching the safety threshold (e.g., exceeding) 95% of the total.

[0101] Once this mechanism is triggered, the system immediately performs the following actions:

[0102] First, logical circuit breaking: The system forcibly interrupts the energy-saving optimization process in S304, locks the current frequency reduction operation, prohibits any form of deceleration command, and prevents further deterioration of water quality.

[0103] Secondly, forced reset: The intelligent control unit bypasses the conventional regulation circuit and directly sends a "safe frequency" command (usually set to 95% or 100% of the rated frequency) to the frequency converter. This operation can instantly increase the transmembrane pressure difference of the secondary reverse osmosis membrane, and use the "dilution effect" under high pressure to quickly reduce the conductivity of the permeate, prioritizing the safety of the feed water to the electro-deionization module.

[0104] Finally, dead zone locking: To prevent the system from frequently starting and stopping near the critical point, causing mechanical fatigue and hydraulic oscillations in the frequency converter and water pump, the system is set with a "dead zone time". Within 10 to 15 minutes after the circuit breaker is triggered, even if the water quality data recovers to good condition, the system will forcibly block the activation signal of the energy-saving mode to maintain a high-pressure safe operating state.

[0105] The terminal fine processing and EDI load coordination compensation step S40 specifically includes the following sub-steps:

[0106] S401, Ultraviolet Photochemical Inactivation. The permeate water, after secondary reverse osmosis treatment, is first introduced into a pipeline ultraviolet sterilizer. The main structure of this sterilizer is made of 316L sanitary-grade stainless steel, and internally houses a low-pressure amalgam lamp protected by a high-purity quartz sleeve. When excited, the lamp emits short-wave ultraviolet light with a center wavelength of 253.7 nanometers. When water flows through the irradiation chamber, the photon energy of this specific wavelength is strongly absorbed by the nucleic acids in the nuclei of residual microorganisms (including bacteria, viruses, and spores). The photochemical reaction causes adjacent pyrimidine bases in the nucleic acid molecule chain to dimerize, forming cyclobutanepyrimidine dimers, thereby physically blocking the genetic replication and protein synthesis pathways of the microorganisms, rendering them completely inactive. To ensure the inactivation effect, the intelligent control unit dynamically calculates the current ultraviolet radiation dose based on real-time collected flow data and ultraviolet light intensity data. Its calculation logic follows the following engineering formula:

[0107] ;

[0108] in: This represents the actual effective ultraviolet radiation dose, expressed in millijoules per square centimeter. The system requires this value to always be greater than 30. This represents the radiation intensity monitored in real time by an ultraviolet light intensity sensor installed on the cavity wall, measured in milliwatts per square centimeter. The effective water volume of the ultraviolet reaction chamber is expressed in liters and is a fixed constant. This represents the real-time instantaneous flow rate through the sterilizer, measured in liters per second. The ultraviolet transmittance correction factor for water is related to the turbidity of the water body and ranges from 0.8 to 0.95.

[0109] If calculated If the water level falls below the set threshold, the intelligent control unit will trigger an audible and visual alarm and automatically close the water discharge valve to prevent substandard water from entering subsequent processes.

[0110] S402, Particulate Interception and Debris Removal. Water irradiated with ultraviolet light then enters a precision filter. This filter is filled with a pleated microporous membrane cartridge, preferably made of polyethersulfone or polypropylene, with an absolute filtration precision set between 0.2 and 0.45 micrometers. The core function of this filter is not only to intercept any suspended particles and colloids in the water, but more importantly, to physically retain the debris and cell fragments of microorganisms killed in the preceding steps. If these organic debris enters the downstream environment, they will not only mechanically clog the extremely narrow concentrate channels within the electro-deionization module, but the small organic molecules produced by their decomposition will also become a "biological nutrient source," inducing the secondary reproduction of nutrient-poor microorganisms remaining within the electro-deionization module, forming difficult-to-remove biological slime. Through this process, the system effectively controls the sludge density index (SDI) of the electro-deionized influent below 1.0, fundamentally preventing the risk of biofouling of the membrane stack. For routine maintenance of precision filters, the system has reserved integrity testing interfaces (such as bubble point test ports) to periodically verify whether the filter element has minor damage, which is a conventional technical means in this field.

[0111] S403, real-time ion load calculation and feedforward control. The intelligent control unit samples the influent conductivity of the electro-deionization module once per second. The system monitors the real-time flow rate of the freshwater chamber. Based on Faraday's law of electrolysis, the system maps the microscopic ion migration requirements into a macroscopic current control signal. To maintain continuous resin regeneration and ensure stable product water resistivity, the intelligent control unit constructs the following dynamic current setting formula, which establishes a linear mapping relationship between the influent load and the operating current:

[0112] ;

[0113] in, This represents the output current setting of the DC power supply, in amperes. The coefficient representing conductivity and current conversion factor is a combination of Faraday constant, average valence state of ions and effective cross-sectional area of ​​membrane stack. It is obtained by standard solution calibration during the system commissioning phase and its value is usually between 0.5 and 1.2. The real-time flow rate of the freshwater chamber is expressed in liters per second. This represents the real-time measured conductivity of the feed water, measured in microsiemens per centimeter. It's important to note that, in the absence of external contamination, the product water from the secondary reverse osmosis unit is the feed water for the EDI system. equal ; This represents the conductivity of ideal pure water; Represents the basic current component used to maintain the production of hydrogen ions and hydroxide ions by electrolyzing water to regenerate the resin, usually set at 10% to 20% of the module's rated current; Is the dynamic ion load.

[0114] S404, Synergistic compensation of electrochemical energy and mechanical energy. When step S30 performs voltage reduction for energy conservation, resulting in an increase in the influent water conductivity rising, the system recognizes an increase in ion load. According to the formula in S403, the calculated will increase synchronously. The intelligent control unit sends a new current command to the rectifier power supply supporting the electrodeionization module, automatically increasing the DC voltage applied between the positive and negative plates of the membrane stack. The increase in voltage directly enhances the DC electric field strength perpendicular to the water flow direction. According to the physical principle of the Nernst - Planck equation, the directional migration speed of impurity ions in water under the action of an electric field is proportional to the electric field strength. Therefore, the enhanced electric field force can accelerate the migration of ions to the concentrated water chamber, offsetting the penetration risk brought by the increase in influent concentration. The essence of this process is to use precisely regulated electrochemical energy (increased rectifier power consumption) to compensate for the mechanical energy reduced by the previous stage for energy conservation (reduced high-pressure pump power consumption). Since the electrodeionization technology has a very high energy efficiency ratio in removing trace ions, this energy scheduling strategy achieves the global optimum of the total energy consumption of the entire system on the premise of ensuring the final product water quality meets the standard.

[0115] S405, Feedwater resistivity feedback correction. While performing feedforward current compensation, the intelligent control unit continuously monitors the online resistivity of the product water. If the monitored value shows a downward trend and is lower than the set warning line (e.g., 17 megaohm·centimeters), the system will activate the PID feedback regulation loop and, on the basis of add an additional correction component to forcibly increase the working current until the product water resistivity returns to a steady state. This dual control loop ensures that the system has extremely high anti-interference ability and stability when dealing with fluctuations in influent water quality.

[0116] S406, Vacuum ultraviolet photodecarbonization. The high-purity water treated by electrodeionization is pumped into the TOC remover 24. The core component of this device is a special dual-wavelength ultraviolet lamp tube, and its key feature is the use of a high-purity synthetic quartz sleeve, which has extremely high transmittance for light with a wavelength of 185 nanometers, overcoming the defect of ordinary natural quartz glass absorbing short-wave ultraviolet light. When the vacuum ultraviolet light with a wavelength of 185 nanometers irradiates the water body, it triggers a dual degradation effect:

[0117] On the one hand, direct photolysis: High-energy photons directly impact organic molecules, and their energy is higher than the bond energy of most organic chemical bonds, directly breaking the carbon-carbon chain or carbon-hydrogen bond;

[0118] On the other hand, indirect oxidation: photon energy breaks down water molecules, generating hydroxyl radicals with extremely strong oxidizing power. These radicals have an oxidation potential as high as 2.8 volts, sufficient to completely oxidize and decompose trace amounts of residual organic matter in the water. The core reaction mechanism is shown in the following equation:

[0119] ;

[0120] organic matter Inorganic ions;

[0121] in, Represents water molecules; Represents the energy of vacuum ultraviolet photons with a wavelength of 185 nanometers (wherein) is Planck's constant. (referring to the optical frequency). Representing a hydrogen radical, it is a hydrogen atom in a high-energy excited state. Representing the hydroxyl radical, it is the core oxidizing agent in the reaction; The inorganic ions represent carbon dioxide produced after organic matter is oxidized; the inorganic ions represent nitrate ions, sulfate ions, etc., produced after heteroatoms (such as nitrogen and sulfur) in organic matter are mineralized.

[0122] This step reduces the residual total organic carbon content in the water from micrograms to nanograms, typically below 5 ppb. The carbon dioxide produced by decomposition then dissolves in the water to form carbonate ions.

[0123] S407, end-polishing with nuclear-grade resin. Water, after decarbonization treatment, enters a polishing mixed bed. This mixed bed is filled with non-renewable nuclear-grade polishing resin. This resin is a homogeneous mixture of highly cross-linked strong acid cation exchange resin and strong base anion exchange resin at a volume ratio of 1:1 or 1:1.5. The nuclear-grade resin undergoes special purification treatment, exhibiting a conversion rate greater than 99.9% and an extremely low self-dissolution rate. When water flows through the resin bed, hydrogen and hydroxide ions on the resin undergo thorough ion exchange with the remaining trace metal ions, non-metal ions, and carbonate ions generated in step S406 in the water. The exchanged ions are firmly adsorbed onto the framework, while hydrogen and hydroxide ions are released and combine to form water molecules.

[0124] This step completely eliminates trace amounts of conductive substances remaining in the water, allowing the resistivity of the effluent to reach the theoretical limit, which is achieved at 25 degrees Celsius:

[0125] ;

[0126] This represents the final online resistivity of the produced water after polishing and mixed bed treatment; The unit representing resistivity is megaohm-cm.

[0127] This signifies that the produced water quality has reached the standard of electronic-grade ultrapure water and can be directly supplied to terminal equipment.

[0128] To illustrate the working principle of this invention more intuitively, a typical modular ultrapure water preparation embodiment is described in detail below. This embodiment verifies the operational efficiency of a modular ultrapure water preparation system with a rated production capacity of 10 cubic meters per hour under low-temperature conditions in winter.

[0129] Phase 1: Raw water temperature control and pretreatment:

[0130] Raw water is introduced into the system at a flow rate of 18 cubic meters per hour, with an initial temperature of 12 degrees Celsius. The intelligent control unit uses a PID algorithm to control the heat exchanger, raising and stabilizing the water temperature at 25.0 ± 0.2 degrees Celsius, establishing a standard thermodynamic environment for the entire system. The chemical dosing device precisely adds scale inhibitor at a concentration of 3.0 ppm based on the real-time flow rate, with a calculated dosage of approximately 0.054 liters per hour.

[0131] Phase Two: Establishment of First-Stage Reverse Osmosis Baseline Parameters

[0132] The first-stage RO high-pressure water pump operates at the industrial frequency (50Hz), with an output pressure of 1.2 MPa and a recovery rate set at 65%. After data acquisition by the first conductivity sensor and temperature compensation, the baseline conductivity of the first-stage reverse osmosis permeate was measured to be stable at 10.5 μSiemens / cm. This data serves as the baseline input for subsequent models.

[0133] Phase 3 and 2 reverse osmosis energy efficiency optimization actions:

[0134] In the initial stage (T=0 to 10 minutes), the secondary RO high-pressure water pump operates at 48 Hz, with an inlet pressure of 1.4 MPa and a predicted conductivity of the secondary reverse osmosis permeate. The value is 1.8 microSiemens / cm. The system has a preset EDI inlet water safety threshold. The value is 40 microSiemens per centimeter. The intelligent control unit determines the current... much smaller 85% of the capacity falls under the "redundant operating condition".

[0135] At T=10 minutes, the system initiates energy efficiency optimization. For example... Figure 3 As shown, the pump frequency was gradually reduced in steps at a rate of 0.5 Hz / 2 min. As the frequency gradually decreased from 48 Hz to 38 Hz (T = 10 to 40 minutes), the transmembrane pressure difference decreased, the dilution effect weakened, and this led to a change in the predicted conductivity of the second-stage reverse osmosis permeate. For example... Figure 5 As shown by the dashed line, the predicted conductivity of the produced water increased from 1.8 μS / cm to 4.5 μS / cm during this process.

[0136] When the frequency drops to 38Hz, the intelligent control unit detects that the pump outlet pressure is close to the minimum suction pressure (0.2 MPa) required by the EDI booster pump, which touches the hydraulic safety bottom line of the system. Therefore, it stops reducing the frequency and maintains operation at 38Hz, even though the water quality is still relatively high at this time.

[0137] Phase Four: Synergistic Compensation of Electrochemical Energy for Mechanical Energy

[0138] During the frequency reduction process, the intelligent control unit synchronously monitors the increase in ion load entering the EDI system. Based on the preset feedforward model:

[0139] ;

[0140] The real-time flow rate of the freshwater chamber Approximately 2.78 liters per second (10 cubic meters per hour). With the increase in influent conductivity... As the power consumption increases, the control unit drives the EDI rectifier power supply to increase its output current, and the EDI operating power consumption rises from the basic 2.0 kW to 2.8 kW (an increase of 0.8 kW).

[0141] like Figure 4 As shown, the power consumption of the EDI system (dotted line) increased from a base of 2.0 kW to 2.8 kW (an increase of 0.8 kW); while the power of the secondary RO high-pressure water pump, as the main energy-consuming device in the system, decreased significantly with the cube of the frequency (dashed line), from 4.5 kW to approximately 2.2 kW (a reduction of 2.3 kW). Ultimately, the total system energy consumption (solid line) achieved a net reduction of approximately 1.5 kW (an energy saving rate of approximately 23%).

[0142] During this period, such as Figure 5 As shown by the solid line, although the water quality fluctuated significantly in the middle, the resistivity of the final product water remained stable above 18.2 megohm-cm after end polishing through feedforward compensation adjustment.

[0143] In summary, this embodiment intuitively verifies that by utilizing the differences in energy consumption characteristics between the reverse osmosis unit and the EDI unit, the system actively reduces the high-pressure pumping energy consumption (mechanical energy) of the second-stage reverse osmosis and precisely compensates for it using the work done by electric field migration (electrochemical energy), which has a higher energy efficiency ratio. This achieves a significant reduction in mechanical energy of 2.3 kW with a mere 0.8 kW increase in electrical energy. Simultaneously, the feedforward compensation mechanism based on model prediction effectively eliminates the hysteresis fluctuations in traditional feedback control, ensuring that the final product water quality remains consistently superior to the industry standard (18.2 MΩ·cm) even during significant adjustments to power parameters. This successfully solves the technical challenge of balancing energy consumption optimization and water quality safety in traditional ultrapure water processes.

Claims

1. A modular ultrapure water preparation system with intelligent controllability, characterized in that, It includes a pretreatment unit, a primary reverse osmosis system, a secondary reverse osmosis system, and a terminal fine treatment system connected sequentially along the water flow direction, as well as an intelligent control unit electrically connected to the secondary reverse osmosis system and the terminal fine treatment system; The two-stage reverse osmosis system includes a two-stage RO high-pressure water pump and a two-stage reverse osmosis unit. The two-stage RO high-pressure water pump is used to drive water flow into the two-stage reverse osmosis unit. The terminal fine processing system includes an EDI system; The intelligent control unit is configured to execute an energy efficiency optimization strategy: The predicted conductivity of the permeate from the secondary reverse osmosis unit is obtained, the operating frequency of the secondary RO high-pressure water pump is adjusted according to the predicted conductivity, and the operating current of the EDI system is adjusted synchronously according to the predicted conductivity.

2. The modular ultrapure water preparation system with intelligent controllability according to claim 1, characterized in that, The pretreatment unit and the first-stage reverse osmosis system include a raw water tank, a raw water pump, a multi-media filter, an activated carbon filter, a filter water tank, a first-stage RO booster pump, a security filter, a first-stage RO high-pressure pump, a first-stage reverse osmosis system, and a first-stage RO water tank, which are connected sequentially along the water flow direction. The outlet of the primary RO water tank is connected to the inlet of the secondary RO high-pressure water pump via a secondary RO booster pump.

3. The modular ultrapure water preparation system with intelligent controllability according to claim 1, characterized in that, The terminal fine treatment system includes an EDI booster pump, an ultraviolet sterilizer, a precision filter, the EDI system, a pure water tank, a pure water pump, a total organic carbon remover, a polishing mixed bed, and a terminal filter, which are connected in sequence along the water flow direction. The product water outlet of the secondary reverse osmosis unit is connected to the inlet of the EDI booster pump through a secondary RO water tank.

4. The modular ultrapure water preparation system with intelligent controllability according to claim 1, characterized in that, It also includes a first conductivity sensor installed on the product water side of the first-stage reverse osmosis system, a frequency feedback device installed at the second-stage RO high-pressure water pump, and a pressure sensor installed on the inlet water side of the second-stage reverse osmosis unit. The intelligent control unit is connected to the first conductivity sensor, the frequency feedback device and the pressure sensor respectively, and is used to obtain the reference conductivity of the first-stage RO permeate, the real-time operating frequency of the second-stage RO high-pressure water pump and the inlet pressure of the second-stage reverse osmosis unit.

5. The modular ultrapure water preparation system with intelligent controllability according to claim 4, characterized in that, The intelligent control unit is configured to run a solute permeation and pressure response model; The solute permeation and pressure response model is used to calculate the predicted conductivity of the permeate based on the baseline conductivity of the first-stage RO permeate and the inlet pressure using a conductivity prediction formula; wherein the predicted conductivity of the permeate is positively correlated with the baseline conductivity of the first-stage RO permeate and negatively correlated with the inlet pressure.

6. The modular ultrapure water preparation system with intelligent controllability according to claim 5, characterized in that, The intelligent control unit is configured to execute the following operating condition determination and adjustment logic: The predicted conductivity of the produced water is compared with the safety threshold of the EDI influent. When the predicted conductivity of the produced water is less than a first preset ratio of the EDI influent safety threshold, it is determined to be a redundant operating condition. The intelligent control unit uses the perturbation observation method to perform a step-down adjustment of the operating frequency of the secondary RO high-pressure water pump; The first preset ratio is 85%; The EDI inlet water safety threshold is a critical safety boundary set based on the physicochemical characteristics of the electro-deionization module. This critical safety boundary is set based on the mechanism that if the conductivity of the inlet water exceeds the EDI inlet water safety threshold, the resin bed will fail rapidly and a breakthrough phenomenon will occur.

7. The modular ultrapure water preparation system with intelligent controllability according to claim 6, characterized in that, The intelligent control unit is also configured to execute a safety interlock fuse mechanism: When the predicted conductivity of the produced water is greater than the safety threshold of the EDI inlet water, it is determined to be a risky operating condition. The intelligent control unit forcibly interrupts the energy-saving optimization process and controls the operating frequency of the secondary RO high-pressure water pump to be forcibly reset to the safe frequency. The dilution effect under high pressure is used to quickly reduce the conductivity of the produced water and prevent unqualified water from entering the EDI system.

8. The modular ultrapure water preparation system with intelligent controllability according to claim 6, characterized in that, The intelligent control unit is also configured to execute optimal hold logic: When the predicted conductivity of the produced water is between a first preset ratio and a second preset ratio of the EDI inlet water safety threshold, it is determined to be the optimal operating condition, and the intelligent control unit controls the secondary RO high-pressure water pump to maintain the current operating frequency unchanged. The second preset ratio is 95%.

9. The modular ultrapure water preparation system with intelligent controllability according to claim 1, characterized in that, The intelligent control unit's logic for adjusting the operating current of the EDI system is as follows: Following Faraday's law of electrolysis, a linear mapping relationship between the influent load and the operating current is established; the specific calculation logic is as follows: First, calculate the difference between the predicted conductivity of the produced water or the real-time measured conductivity of the influent and the conductivity of the ideal pure water. Combine the difference with the real-time flow rate and the pre-calibrated conductivity and current conversion coefficient to calculate the dynamic current component used to remove the dynamic ion load. Then, superimpose the dynamic current component with the basic current component used to maintain resin regeneration to obtain the final output current setting value. When the operating frequency of the secondary RO high-pressure water pump decreases, causing the predicted conductivity of the product water to increase, the calculated current setpoint increases synchronously. The intelligent control unit controls the operating current of the EDI system to increase, thereby enhancing the DC electric field strength perpendicular to the water flow direction and accelerating the migration of ions to the concentrate chamber.

10. The modular ultrapure water preparation system with intelligent controllability according to claim 2, characterized in that, The pretreatment unit also includes a chemical reagent dosing device and a heat exchanger; The chemical agent dosing device is located at the front end of the multi-media filter and is used to add scale inhibitors or bactericides. The heat exchanger is located at the rear end of the raw water pump and is used to regulate the water temperature entering the first-stage reverse osmosis system.

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