A dosing system and control and treatment system for zero discharge of polysilicon wastewater

Abstract

This invention belongs to the field of industrial water treatment technology, specifically relating to a dosing system and control system for zero discharge of polysilicon wastewater. The system comprises a dosing control system and multiple chemical treatment units. Each chemical treatment unit includes a dosing unit, an inlet monitoring unit, and an outlet detection unit. The inlet monitoring unit monitors the influent's parameters, and the outlet detection unit detects the effluent's parameters. Based on the deviation between the set target effluent quality value and the detected target effluent quality parameters, a mathematical model for chemical dosing is used to calculate the chemical dosage. The dosing control system adjusts the chemical dosage in the dosing unit accordingly. This invention establishes a functional relationship between the influent and effluent water quality parameters and the chemical dosage, overcoming the lag in dosage adjustment caused by the reliance on effluent water quality in conventional chemical self-controlled dosing models. This ensures good accuracy in chemical dosing during both initial and long-term operation.

Description

[0001] This invention belongs to the field of industrial water treatment technology, specifically relating to a dosing system and control and treatment system for zero discharge of polysilicon wastewater.

[0002] The exhaust gas from the polysilicon industrial production process, after absorption and neutralization by lime water and alkali solution, produces effluent containing large amounts of calcium and sodium salts, classifying it as typical high-salt, high-hardness wastewater. In addition, the wastewater also contains pollutants such as silicon, suspended solids, and COD, resulting in a highly complex water quality situation. Based on these characteristics, zero-discharge processes for polysilicon wastewater typically include pretreatment (hardness removal, silicon removal, COD removal, decarbonization, etc.), membrane treatment, and evaporation crystallization systems or units.

[0003] Due to the complexity of polysilicon wastewater, current zero-discharge process control systems for this type of wastewater can only meet basic equipment operation logic control and have not yet achieved full-process automatic control and management of the process. For example, existing automatic control technologies mostly rely on data from the effluent end to control and adjust the dosage of chemicals. In actual operation, there is a certain lag, which affects the accuracy of chemical dosing. In order to ensure that the effluent water quality meets the standards, chemicals are often over-dosed, which not only wastes chemicals but also leads to the risk of COD exceeding the standard in the effluent. When the influent water quality fluctuates greatly, the original dosage of chemicals may be insufficient. If manual intervention is not timely to adjust the dosage of chemicals, it is easy to cause the relevant indicators of the treated effluent to exceed the standard.

[0004] The purpose of this invention is to provide a dosing system and control system for zero discharge of polysilicon wastewater. By establishing a stable and reliable dosing calculation model, a functional relationship is established between the influent and effluent water quality indicators and the dosage of the chemicals. This solves the problem of the lag in dosage adjustment caused by the reliance on the effluent water quality in conventional automatic chemical dosing models. It can better ensure the accuracy of the dosing in the initial stage and long-term operation, and minimize the cost of chemicals.

[0005] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0006] The first objective of this invention is to provide a dosing system for a zero-discharge process of polysilicon wastewater, comprising a dosing control system and multiple reagent treatment units. Each reagent treatment unit is equipped with a dosing unit, an inlet monitoring unit, and an outlet detection unit. The inlet monitoring unit is used to monitor the concentration of the index value of the inlet water, and the outlet detection unit is used to detect the concentration of the index value of the outlet water. The dosing unit, the inlet detection unit, and the outlet detection unit are all signal-connected to the dosing control system. Based on the deviation between the set target values ​​for effluent water quality and the detected target values ​​for effluent water quality indicators, the dosage of chemicals is calculated using a mathematical model for chemical dosing. The dosing control system then adjusts the dosage of chemicals in the dosing unit. The mathematical model for chemical dosing calculation is as follows: ; in, C m The dosage of each calculated reagent is in mg / L; A m The mass equivalent coefficients for each reagent dosage / influent water index are given. A m The range is 0.9 to 11; M m The relative molecular weights of the various drugs are given in g / mol. C a0i The concentration values ​​of the indicators at each inlet are in mg / L; C aei The concentration values ​​of the indicators at each outlet are in mg / L; M ai The values ​​represent the relative molecular weights of the inlet and outlet water indicators, in g / mol. n ai The index values ​​for ion charge at each inlet and outlet are: n m The characteristic ionic charge number of each added agent; C m0 The concentration of ions with the same characteristics as each inlet and each added agent, in mg / L; M m0 The relative molecular weight (g / mol) of ions with the same characteristics as each water inlet and each added agent.

[0007] Furthermore, the dosing unit is equipped with a dosing pump, which controls the flow rate of the chemical dosage. The formula for calculating the flow rate of the dosage is as follows: ; in, Q A The flow rate for the added amount, m 3 / h; Q 0 The inlet flow rate of this control unit is m. 3 / h; ω To prepare the mass concentration of the drug.

[0008] Furthermore, the dosing control system is based on the mathematical model for calculating chemical dosing. It integrates data from the inlet monitoring unit and the outlet detection unit to establish a water quality-chemical dosage regression model. The regression model is used to dynamically verify the chemical dosing / inlet index quality equivalent coefficient. The data is then fed back to the mathematical model and chemical dosing calculation in real time through the processing module to dynamically adjust the chemical dosing.

[0009] Furthermore, the chemical treatment unit includes a sodium sulfate softening and precipitation unit, a dual-alkali softening and precipitation unit, a silicon removal unit, and a decarbonization unit connected in sequence; sodium sulfate is added in the dosing unit of the sodium sulfate softening and precipitation unit to remove Ca from the wastewater. 2+ In the dual-alkali softening and precipitation unit, sodium carbonate, sodium hydroxide, coagulants, and flocculants are added to further remove calcium from the wastewater. 2+ Mg 2+ The silica removal unit adds magnesium salts, sodium hydroxide, coagulants, and flocculants to remove silica from the wastewater; the decarbonization unit adds acid to adjust the pH of the wastewater to a neutral range.

[0010] Furthermore, the inlet monitoring unit and outlet detection unit of the sodium sulfate softening and precipitation unit are used to monitor Ca, respectively. 2+ and SO4 2- The indicator value and the calculation model for sodium sulfate dosage are as follows: ; in, A Na2SO4 It ranges from 1.2 to 1.7.

[0011] Furthermore, the inlet monitoring unit of the dual-alkali softening and sedimentation unit is used to monitor Ca. 2+ Total hardness, pH, and alkalinity; the outlet water detection unit is used to monitor Ca. 2+ Total hardness, pH alkalinity, and effluent turbidity values; The calculation model for sodium carbonate dosage is as follows: ; in, A Na2CO3 It ranges from 1.15 to 1.30.

[0012] Sodium hydroxide dosing calculation model: ; in, A NaOH(Ca) It ranges from 1.2 to 2.7.

[0013] Inlet and outlet C a(Mg²⁺) Based on total hardness and C a(Ca²⁺) The calculation shows that: .

[0014] The dosage of coagulant and flocculant should be adjusted according to the turbidity of the effluent, with a turbidity ≤10 NTU.

[0015] Furthermore, the inlet monitoring unit of the desiliconization unit is used to monitor SiO2 and pH values, while the outlet detection unit is used to monitor SiO2, pH, turbidity, and floc particle size. The added magnesium salt is magnesium chloride, and the calculation model for magnesium chloride dosage is as follows: ; in, A MgCl2 It ranges from 5 to 11; Sodium hydroxide dosing calculation model: ; in, A NaOH(Si) The range is 4 to 11; The dosage of coagulant and flocculant is adjusted according to the effluent turbidity and floc particle size. The turbidity is ≤10 NTU and the percentage of floc particles with a particle size greater than 50 μm is ≥85%.

[0016] Furthermore, the inlet and outlet monitoring units of the decarbonization unit are used to monitor pH and alkalinity values, respectively. The added acid is hydrochloric acid, and the hydrochloric acid dosage calculation model is as follows: ; in, A HCl The value ranges from 0.9 to 1.8.

[0017] Furthermore, a ceramic membrane filtration unit is installed between the silicon removal unit and the decarbonization unit. The ceramic membrane filtration unit is used to remove suspended solids in the wastewater. After the decarbonization unit, there are sequentially installed an ion exchange unit, a COD purification membrane unit, a nanofiltration unit, and an evaporation crystallization unit. The ion exchange unit is used to further remove hardness from the water, the COD purification membrane unit is used to remove COD from the wastewater, the nanofiltration unit is used to separate and remove divalent anions from the wastewater, and the evaporation crystallization unit is used to concentrate and crystallize dissolved salts, thereby achieving solute and solvent separation and "zero discharge" of polysilicon wastewater.

[0018] The second objective of this invention is to provide a control and treatment system for a zero-discharge process of polysilicon wastewater, comprising a main control unit of a control system and the aforementioned dosing system; the main control unit of the control system is signal-connected to the dosing system and a standby treatment unit, and the main control unit of the control system includes an upper management unit and a lower control unit; the upper management unit is used to manually control the operating parameters of the lower control unit and handle abnormal operating conditions of the lower control unit, and the lower control unit is used to monitor abnormal operating conditions of each reagent treatment unit in the dosing system, and after judgment, to process or feed back to the upper management unit and switch to the standby treatment unit.

[0019] Compared with the prior art, the present invention has the following advantages: The dosing system provided by this invention establishes a stable and reliable dosing calculation model, establishing a functional relationship between influent and effluent water quality indicators and chemical dosage. Based on the deviation between the set target value of effluent water quality and the detected target value of effluent water quality indicators, the dosing amount of chemical is calculated through the chemical dosing calculation mathematical model. The dosing control system controls and adjusts and verifies the dosing amount of chemical in the dosing unit in real time. It can ensure the accuracy of dosing in both the initial stage and long-term operation, minimize chemical costs, and solve the problem of the lag in dosing adjustment caused by the reliance on effluent water quality in conventional chemical self-controlled dosing models.

[0020] The control and processing system provided by this invention, based on the upper management computer and lower control computer set in the main control unit of the control system, ensures that the control unit operates automatically under normal operating conditions and low-value abnormal operating conditions through a two-level abnormal operating condition handling mechanism. This saves a lot of labor costs during the project operation phase and greatly improves the automation level of process control. It not only saves a lot of labor and reagent costs during the operation phase, but also ensures the normal operation of the main process to the greatest extent while facilitating the handling of emergencies, thus achieving the goal of automated control and management of complex industrial water treatment zero-discharge processes.

[0021] Figure 1 This is a control flowchart of the control processing system of the present invention.

[0022] Figure 2 This is a control flowchart for the ion exchange unit in Embodiment 1 of the present invention.

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0024] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0025] This invention establishes a stable and reliable dosage calculation model, creating a functional relationship between influent and effluent water quality indicators and the dosage. This overcomes the lag in dosage adjustment inherent in conventional automatic dosing models that rely on effluent water quality. The model effectively ensures dosage accuracy during both initial and long-term operation, minimizing chemical costs. Details are as follows:

[0026] A dosing system for a zero-discharge process of polysilicon wastewater includes a dosing control system and multiple reagent treatment units. Each reagent treatment unit is equipped with a dosing unit, an inlet monitoring unit, and an outlet detection unit. The inlet monitoring unit monitors the concentration of key parameters in the influent, and the outlet detection unit detects the concentration of key parameters in the effluent. All three units are signal-connected to the dosing control system. The reagent treatment units are based on existing zero-discharge processes or systems for polysilicon wastewater treatment. The dosing unit includes a reagent storage tank or silo, a flow pump, etc., all of which are conventionally selected equipment in this field. The inlet and outlet monitoring units include online monitoring instruments for monitoring the water quality at the inlet and outlet.

[0027] The dosing control system sets target values ​​for the effluent quality of each chemical treatment unit, which are conventionally selected by those skilled in the art for treating chemical treatment units. This enables the treatment of polysilicon wastewater to achieve zero discharge. The invention calculates the dosage of chemicals based on the deviation between the set target effluent quality value and the detected target effluent quality indicators using a chemical dosing calculation mathematical model. The dosing control system then adjusts the dosage of chemicals in the dosing unit. The chemical dosing calculation mathematical model is as follows: ; in, C m The dosage of each calculated reagent is in mg / L; A m The mass equivalent coefficients for each reagent dosage / influent water index are given. A m The constants of the regression equation are 0.9 to 11, and are dynamically verified by fitting the data accumulated over a long period of operation. M m The relative molecular weights of the various drugs are given in g / mol. C a0i The concentration values ​​of the indicators at each inlet are in mg / L; C aei The concentration values ​​of the indicators at each outlet are in mg / L; M ai The relative molecular weight, in g / mol, represents the index values ​​for each inlet and outlet. n ai The index values ​​for ion charge at each inlet and outlet are: n m The characteristic ionic charge number of each added agent; C m0 The concentration of ions with the same characteristics as each inlet and each added agent, in mg / L; M m0The relative molecular weight (g / mol) of ions with the same characteristics as each water inlet and each added agent.

[0028] The dosing control system is based on a mathematical model for calculating chemical dosing. It integrates data from the inlet and outlet monitoring units to establish a water quality-chemical dosage regression model. The regression model formula is consistent with the mathematical model for calculating chemical dosing. Its purpose is to obtain the chemical dosing / inlet / outlet index mass equivalent coefficient by fitting a large amount of data on the inlet and outlet water quality (concentration) and chemical dosage during the operation phase. The regression model is used to dynamically verify the chemical dosing / inlet index mass equivalent coefficient, and the processing module feeds it back to the mathematical model and chemical dosage calculation in real time to dynamically adjust the chemical dosage.

[0029] In this invention, the mathematical model for calculating reagent dosage takes the removal of specific pollutants as the target and establishes a definite functional relationship between the reagent dosage and all relevant influent and effluent water quality indicators to obtain a precise and stable reagent dosage, thereby ensuring a stable pollutant removal effect in each process section.

[0030] In a specific embodiment, the dosing unit is equipped with a dosing pump, which controls the flow rate of the added agent. The formula for calculating the flow rate of the added agent is as follows: .

[0031] in, Q A The flow rate for the added amount, m 3 / h; Q 0 The inlet flow rate of this control unit is m. 3 / h; ω To prepare the mass concentration of the drug.

[0032] In a specific embodiment, the reagent treatment unit includes a sodium sulfate softening and precipitation unit, a dual-alkali softening and precipitation unit, a silicon removal unit, and a decarbonization unit connected in sequence. A ceramic membrane filtration unit is also provided between the silicon removal unit and the decarbonization unit to remove suspended solids from the wastewater. Following the decarbonization unit are an ion exchange unit, a COD purification membrane unit, a nanofiltration unit, and an evaporation and crystallization unit, connected in sequence. The ion exchange unit is used to deeply remove residual hardness from the water, the COD purification membrane unit is used to remove COD from the wastewater, and the nanofiltration unit is used to separate and remove major divalent anions in the wastewater, such as SO42-. 2- The evaporation and crystallization unit is used to concentrate and crystallize soluble salts, thereby achieving solute-solvent separation and "zero discharge" of polysilicon wastewater.

[0033] Sodium sulfate is added in the dosing unit of the sodium sulfate softening and precipitation unit to remove most of the calcium from the wastewater. 2+The inlet monitoring unit and outlet detection unit of the sodium sulfate softening and precipitation unit are used to monitor Ca. 2+ and SO4 2- The calculation model for sodium sulfate (Na2SO4) dosage is as follows: .

[0034] In this invention, different Ca 2+ Sodium sulfate was added to raw water of a certain concentration to obtain... A Na2SO4 The initial Na₂SO₄ dosage for the sodium sulfate softening and precipitation unit is 1.2–1.7. During subsequent long-term operation, the Ca concentration can be monitored by the effluent detection unit. 2+ and SO4 2- The indicator values ​​were fine-tuned to meet the effluent requirements. Simultaneously, based on the Na2SO4 dosage calculation model, the adjusted Na2SO4 dosage was compared with the concurrent influent and effluent Ca... 2+ and SO4 2- A regression model for Na2SO4 reagent dosage was established based on the measured values, and the results obtained from the regression model were used for verification. A Na2SO4 Guide and control the dosage of Na2SO4.

[0035] In the dual-alkali softening and precipitation unit, sodium carbonate, sodium hydroxide, coagulants, and flocculants are added to the chemical dosing unit to further remove calcium from the wastewater. 2+ Mg 2+ The monitoring unit at the inlet of the dual-alkali softening and sedimentation unit monitors Ca. 2+ Total hardness, pH, and alkalinity; the outlet water detection unit is used to monitor Ca. 2+ The total hardness, pH alkalinity, and effluent turbidity are monitored, and the dosage of sodium carbonate (Na2CO3) and sodium hydroxide (NaOH) is controlled.

[0036] The calculation model for Na2CO3 reagent dosage is as follows: .

[0037] NaOH dosing calculation model: , where c (H+) =10 -pH .

[0038] Inlet and outlet C a(Mg 2+ ) Based on total hardness and C a(Ca 2+ ) The calculation shows that: .

[0039] In this invention, different Ca 2+ Raw water with varying total hardness, pH, and alkalinity was treated with Na2CO3 and NaOH, respectively, to obtain... A Na2CO3 The value is between 1.15 and 1.30. A NaOH(Ca) The dosage is 1.5–2.7. This gives the initial dosage of Na₂CO₃ and NaOH for the sodium sulfate softening and precipitation unit. During subsequent long-term operation, the dosage can be monitored by the effluent detection unit. 2+ The total hardness, pH alkalinity, and effluent turbidity values ​​were fine-tuned to meet effluent requirements. Simultaneously, based on the calculation model for Na2CO3 and NaOH dosing, the adjusted Na2CO3 and NaOH dosages were compared with the concurrent influent and effluent Ca... 2+ Regression models for Na2CO3 and NaOH reagent addition were established based on the measured values ​​of total hardness, pH alkalinity, and effluent turbidity, respectively. The results of the regression models were then used for verification. A Na2CO3 and A NaOH(Ca) Guide and control the dosage of Na2CO3 and NaOH. The dosage of coagulant and flocculant should be dynamically adjusted according to the effluent turbidity to ensure that the effluent turbidity is below 10 NTU.

[0040] The silica removal unit adds magnesium salt, sodium hydroxide, coagulant, and flocculant to remove most of the silica from the wastewater. The inlet monitoring unit of the silica removal unit monitors the SiO2 and pH values, while the outlet monitoring unit monitors SiO2, pH, turbidity, and floc particle size to control the dosage of magnesium salt and NaOH. The added magnesium salt is magnesium chloride (MgCl2).

[0041] The calculation model for MgCl2 reagent dosing is as follows: .

[0042] Sodium hydroxide dosing calculation model: .

[0043] In this invention, MgCl2 and NaOH are added to raw water with different SiO2 and pH values ​​to obtain... A MgCl2 The value ranges from 5.0 to 11.0. A NaOH(Si)The dosage ranges from 4.0 to 11.0. This yields the initial dosage of MgCl2 and NaOH for the desiliconization unit. During long-term operation, this dosage can be fine-tuned based on the SiO2 and pH values ​​monitored by the effluent detection unit to meet effluent requirements. Simultaneously, based on the calculation model for MgCl2 and NaOH dosage, regression models for MgCl2 and NaOH dosages are established using the adjusted dosages and the measured values ​​of influent and effluent SiO2, pH, turbidity, and floc size during the same period. These regression models are then used for verification. A MgCl2 and A NaOH(Si) Guide and control the dosage of MgCl2 and NaOH. The dosage of coagulant and flocculant should be adjusted according to the effluent turbidity and floc particle size to ensure that the turbidity is between 0 NTU and 10 NTU and the percentage of floc particles with a diameter greater than 50 μm is ≥85%.

[0044] The decarbonization unit adds acid to adjust the pH to a neutral range. The inlet and outlet monitoring units of the decarbonization unit monitor pH and alkalinity values, respectively, and the added acid is hydrochloric acid.

[0045] The calculation model for hydrochloric acid dosage is as follows: .

[0046] In this invention, HCl is added to raw water with different pH and alkalinity to obtain... A HCl The initial HCl dosage for the desiliconization unit is 0.9–1.8. During long-term operation, this dosage can be fine-tuned based on the SiO2 and pH values ​​monitored by the effluent detection unit to meet effluent requirements. Simultaneously, based on the HCl dosage calculation model, a regression model for HCl dosage is established using the fine-tuned dosage and the measured pH and alkalinity values ​​of the influent and effluent during the same period. The results of the regression model are then used for verification. A HCl Provide guidance and control on the dosage of HCl.

[0047] Furthermore, the low efficiency in handling abnormal operating conditions of each process unit affects the overall operational efficiency of the zero-emission process system. This invention addresses this by employing a two-level abnormal operating condition handling mechanism to ensure automatic operation of the control unit under both normal and low-value abnormal conditions. This significantly reduces labor costs during project operation and greatly enhances the automation level of process control.

[0048] A control and treatment system for a zero-discharge process of polysilicon wastewater includes a control system main control unit and the aforementioned dosing system; The main control unit of the control system is connected to the dosing system and the backup processing unit. The main control unit includes an upper management computer and a lower control computer. The upper management computer is used to manually control the operating parameters of the lower control computer and handle abnormal operating conditions of the lower control computer. The lower control computer is used to monitor the abnormal operating conditions of each agent processing unit in the dosing system, and after judgment, it will handle the situation or feed back to the upper management computer and switch to the backup processing unit.

[0049] In this invention, the zero-discharge process for polysilicon wastewater comprises, in sequence, a sodium sulfate softening and precipitation unit, a dual-alkali softening and precipitation unit, a silicon removal unit, a decarbonization unit, a ceramic membrane filtration unit, an ion exchange unit, a COD purification membrane unit, a nanofiltration unit, and an evaporation and crystallization unit. It is understood that each of the sodium sulfate softening and precipitation unit, dual-alkali softening and precipitation unit, ceramic membrane filtration unit, ion exchange unit, COD purification membrane unit, nanofiltration unit, and evaporation and crystallization unit, as well as the associated electrical equipment and instruments, is equipped with an identical backup unit or equipment and instruments.

[0050] The main control unit of the control system can operate in automatic mode, remote manual mode, and local control box mode. The electrical equipment has local manual operation function, and the upper management computer has soft manual operation function. It can independently start and stop operations. All operating parameters and alarm information of the control system are stored in the upper management computer, which supports instantaneous trend, real-time data and historical trend query.

[0051] The methods by which the lower-level controller handles abnormal operating conditions of each unit, such as... Figure 1 As shown, it includes the following steps: Step 1: The lower-level controller determines whether the operation is normal based on the values ​​monitored online by each unit device and instrument.

[0052] Step 2: When the lower-level controller monitors any abnormal operating condition of any processing unit in the dosing system, it can control the equipment, instruments, valves, etc. to perform operations in real time without authorization from the upper-level management unit, and automatically switch to the standby unit.

[0053] Step 3: The lower-level controller further determines whether the abnormal operating condition is a low-value abnormality or a high-value abnormality.

[0054] Step 4: When the lower-level controller determines that the control unit is in a low-value abnormal condition, it automatically starts the processing program, controlling the equipment, instruments, valves, etc. to perform operations such as adding chemicals, cleaning, rinsing, and regeneration, and sends alarms and abnormal information to the upper-level management unit in real time. The operator on the upper-level management unit's display screen continuously tracks and monitors the execution status and results of the processing program. If the monitored value is still low-value or high-value abnormal after the automatic processing program, it sends a secondary abnormal information to the upper-level management unit in real time. The operator on the upper-level management unit's display screen reports the secondary abnormality to the management personnel, organizes manual handling of the relevant abnormality, and restores the system to normal operating conditions. When the lower-level controller determines that the control unit is in a low-value abnormal condition, it sends an alarm and abnormal information to the upper-level management unit in real time. After receiving the alarm information of abnormal operating conditions of the equipment and instruments, the operator on the upper-level management unit's display screen starts the abnormality handling program according to the abnormality, or reports to the management personnel, organizes timely handling of the relevant abnormality, and restores the system to normal operating conditions. After restoring the system to normal operating conditions, it switches back to the processing unit.

[0055] The sodium sulfate softening and sedimentation unit is classified into several abnormal operating conditions. Low-value abnormal conditions are characterized by low outlet flow rate, with online monitoring parameters including inlet and outlet flow rates. High-value abnormal conditions are characterized by scale buildup in the tank and pipe blockage, with online monitoring parameters including inlet and outlet flow rates. A low-value abnormality is defined as an outlet flow rate lower than 85% of the inlet flow rate, and the handling of this condition includes hydraulic flushing of the pipes. A high-value abnormality is defined as an outlet flow rate lower than 50% of the inlet flow rate, and the handling of this condition includes shutdown and maintenance: organizing inspections of the tank, equipment, and pipes, scale removal, or emergency drainage.

[0056] Low-value abnormal operating conditions in the dual-alkali softening sedimentation unit and the desiliconization unit are characterized by abnormally high turbidity or poor floc settling, with online monitoring parameters including turbidity and floc particle size distribution. High-value abnormal operating conditions are characterized by scaling in the tank or blockage in the pipes, with online monitoring parameters including inlet and outlet flow rates. When the effluent turbidity is >10 NTU or the percentage of floc particles larger than 50 μm is <85%, it is considered a low-value abnormality. The treatment for low-value abnormal operating conditions in the dual-alkali softening sedimentation unit and the desiliconization unit is to increase the dosage of coagulant and flocculant. When the instantaneous flow rate of the outlet pipe is lower than 75% of the flow rate of the inlet pipe, it is considered a high-value abnormality. The treatment for high-value abnormal operating conditions in the dual-alkali softening sedimentation unit and the desiliconization unit includes shutdown and maintenance: triggering an alarm, and after receiving the information, the management personnel of the upper management unit organize inspections of the tank, equipment, and pipes, scale removal, or emergency discharge measures.

[0057] The low-value abnormal operating conditions of the ceramic membrane filtration unit are excessive transmembrane pressure difference or a sudden drop in permeate flow rate. The online monitoring parameters are the inlet and outlet pressures of the membrane module or the influent and permeate flow rates. The high-value abnormal operating condition is an abnormal increase in turbidity, and the online monitoring parameter is turbidity. The handling of the low-value abnormal operating conditions of transmembrane pressure difference and permeate flow rate of the ceramic membrane filtration unit is backwashing and chemical cleaning, respectively: when a sudden change in transmembrane pressure difference is detected exceeding 0.05 MPa, it is determined to be a low-value abnormality, and the backwashing program is automatically triggered to backwash the ceramic membrane with a set flushing water volume, repeating 3 to 10 times. After each flushing, drainage and backwash tank replenishment are started. When a sudden drop in permeate flow rate is detected exceeding 15% of the influent flow rate, it is determined to be a low-value abnormality, and the chemical cleaning program is automatically triggered to chemically clean the membrane module with a designed chemical flushing volume. The handling of the high-value abnormal operating conditions of the ceramic membrane filtration unit is shutdown and maintenance: when the effluent turbidity exceeds the high value, an alarm is triggered, and the upper management personnel receive the information and organize the replacement of the membrane module.

[0058] The low-value abnormal operating condition of the ion exchange unit is defined as the cumulative permeate flow reaching the set regeneration value, with the online monitoring parameter being the effluent flow rate. The high-value abnormal operating condition is defined as the total hardness of the effluent exceeding 5 mg / L, with the online monitoring parameter being the total hardness. Control of the ion exchange unit under the low-value abnormal operating condition includes resin regeneration: when the cumulative permeate flow reaches the set regeneration value, it is determined to be a low-value abnormality, and the resin regeneration program is automatically started. Control of the ion exchange unit under the high-value abnormal condition involves shutdown and maintenance: when the effluent hardness exceeds 5 mg / L, it is determined to be a high-value abnormality, an alarm is triggered, and after receiving the information, the management personnel on the upper-level management system organize the replacement of the ion exchange resin.

[0059] Low-value abnormal operating conditions of the COD purification membrane unit are characterized by excessive transmembrane pressure difference and a sudden drop in permeate flow. Online monitoring parameters include the inlet and outlet pressures of the membrane module and the flow rates of the feed and concentrate sides. High-value abnormal operating conditions are characterized by excessive COD in the effluent. Online monitoring parameters include the COD at both the inlet and outlet ends. Control for low-value abnormal operating conditions of the COD purification membrane unit involves shutdown and flushing: when the transmembrane pressure difference increases sharply or the permeate flow rate decreases by more than 15%, it is determined to be a low-value abnormality, and a shutdown and flushing procedure is automatically triggered. Control for high-value abnormal operating conditions of the COD purification membrane unit involves shutdown and maintenance: when the effluent COD exceeds the high value, it is determined to be a high-value abnormality, triggering an alarm. Upon receiving the information, the upper-level management personnel organize the replacement of the membrane module.

[0060] The low-value abnormal operating conditions of the nanofiltration unit are abnormal transmembrane pressure difference and a sudden drop in permeate flow rate, with online monitoring parameters being the inlet and outlet pressures of the inter-stage pump and the flow rates on the feed and permeate sides, respectively. The high-value abnormal operating condition is an abnormal increase in conductivity, with online monitoring parameters being the conductivity on the feed and concentrate sides. The control for the low-value abnormal operating conditions of the nanofiltration unit is shutdown and flushing: when the transmembrane pressure difference between the feed and concentrate increases sharply or the permeate flow rate drops sharply by more than 15%, it is determined to be a low-value abnormality, and the shutdown and flushing procedure is automatically triggered. The control for the high-value abnormal operating conditions of the nanofiltration unit is shutdown and maintenance: when the conductivity on the concentrate side exceeds the limit, it is determined to be a high-value abnormality, an alarm is triggered, and after receiving the information, the upper-level management personnel organize the replacement of the membrane module.

[0061] Abnormal operating conditions of the evaporation crystallization unit include: severe foam entrainment in the secondary steam, demister blockage, and blockage in the feed pipe or feed plate heat exchanger. The monitored parameters are condensate drainage conductivity, pressure before and after the demister, and feed flow rate. Severe foam entrainment in secondary steam: When conductivity > 10 μS / cm, it is judged as a low-value anomaly, and the defoamer dosing device is automatically controlled to add defoamer; if the conductivity is still > 10 μS / cm after adding defoamer, it is judged as a high-value anomaly, triggering an alarm and feedback to the upper management unit, and arranging for manual inspection and cleaning of the demister screen. Demister blockage: When the pressure difference before and after the demister is > 5 kPa, it is judged as a low-value anomaly, triggering a shutdown flush, and automatically opening the demister screen cleaning switch valve for 60 seconds; if the pressure difference before and after the demister is still > 5 kPa after flushing, it is judged as a high-value anomaly, triggering an alarm, and arranging for manual inspection and cleaning of the screen. Blockage in the feed pipe or feed plate heat exchanger: When the feed flow rate is less than 15% of the normal flow rate, it is judged as a low value abnormality and the pipe flushing program is automatically started; when the feed flow rate is less than 50% of the normal flow rate, it is judged as a high value abnormality and an alarm is triggered. After receiving the information, the management personnel of the upper management unit organize the unblocking of the feed pipe.

[0062] Step 5: After the low-value or high-value abnormal operating conditions of the control unit are handled and restored to their original state, the system continues to monitor water quality indicators, equipment, and instruments.

[0063] The following specific examples will provide further explanation.

[0064] Example 1 A zero-discharge process for polysilicon wastewater utilizes the aforementioned dosing system and control system (such as...) Figure 2 (As shown) the process, wherein the polysilicon wastewater is polysilicon tail gas washing wastewater, Ca 2+ 5878 mg / L, Mg 2+ 64 mg / L, SO4 2- : 821 mg / L; SiO2: 24.4 mg / L; Total water volume: 38.8 m³ 3 / h, wastewater sequentially enters the sodium sulfate softening and precipitation unit, the dual-alkali softening and precipitation unit, the silicon removal unit, the decarbonization unit, the ceramic membrane filtration unit, the ion exchange unit, the COD purification membrane unit, the nanofiltration unit, and the evaporation and crystallization unit. This includes the following steps:

[0065] Step 1: Monitor the Ca content of the influent to the sodium sulfate softening and sedimentation unit in real time at both the inlet and outlet ends. 2+ and SO4 2- Concentration, setting the Ca content of the effluent water quality 2+ (1000 mg / L), Ca was detected in real time at the outlet. 2+ (994 mg / L) and SO4 2- (5516 mg / L).

[0066] The calculation model for Na2SO4 reagent dosage is as follows: , A Na2SO4 It is 1.65.

[0067] The calculated dosage of Na₂SO₄ is 26500 mg / L, and the flow rate of the Na₂SO₄ dosing pump is 10.3 m³ / L. 3 The reagent concentration is 10%, and the solid feed rate is 1.03 t / h. The Ca content of the effluent is monitored in real-time by online monitoring instruments at the effluent outlet. 2+ and SO4 2- Concentration is dynamically verified based on a regression model (i.e., by fitting a large amount of data on influent and effluent water quality (concentration) and dosage during operation using a mathematical model for calculating chemical dosing, to obtain the chemical dosing / influent / effluent index mass equivalent coefficient). This coefficient is then fed back to the mathematical model and chemical dosing calculation in real time through the processing module, allowing for fine-tuning of the Na2SO4 dosage, dosing pump flow rate, and solid feed rate.

[0068] The sodium sulfate softening and precipitation unit exhibits low-value abnormal operating conditions, characterized by low effluent flow rate in the outlet pipe (monitored online for both inlet and outlet pipe flow rates). High-value abnormal operating conditions include scaling in the tank and pipe blockage (monitored online for both inlet and outlet pipe flow rates). The normal inlet flow rate is 38.8 m³ / h. 3 / h, when the instantaneous flow rate of the outlet pipe is detected to be below 33.0m³ / h. 3 When the flow rate is below 19.4 m³ / h, it is considered an abnormally low value. The lower-level controller of the sodium sulfate softening and precipitation unit controls the flushing equipment and pipelines to perform hydraulic flushing. 3 When the value reaches / h, it is determined to be an abnormal high value. The lower-level controller of the sodium sulfate softening and precipitation unit will upload an alarm signal to the upper-level management unit. The management personnel will then organize inspections of the water tank, equipment, and pipelines, as well as scale removal or emergency drainage.

[0069] Step 2: Real-time monitoring of Ca at the inlet of the dual-alkali softening and sedimentation unit. 2+ (994 mg / L), total hardness (2643 mg / L), pH (7.1), alkalinity (CO3) 2- =0 mg / L, HCO3 - =58.9mg / L) and flow rate (52.5m 3 / h), set the Ca of the effluent water quality. 2+ (40 mg / L), total hardness (150 mg / L), pH (10.7), alkalinity (HCO3) - =0), Ca was monitored in real time at the outlet. 2+ (21.8 mg / L), total hardness (137 mg / L), pH (10.6), alkalinity (HCO3) - =0mg / L), turbidity (less than 10NTU), and floc size (percentage of particles larger than 50μm ≥85%).

[0070] Based on the Na2CO3 reagent dosage calculation model: , A Na2CO3 It is 1.16.

[0071] Based on the NaOH reagent dosing calculation model: , A NaOH(Ca) It is 1.28.

[0072] Based on this, the dosage of the reagents (Na2CO3: 2915 mg / L, NaOH: 160 mg / L) and the flow rate of the dosing pump (Na2CO3: 1.53 m³ / L) were calculated. 3 The dosage of flocculants PFS and PAM (PFS: 50 mg / L, PAM: 2 mg / L), the flow rate of the dosing pump (PFS: 2.62 L / h (100% concentration), PAM: 105 L / h (0.1% concentration)) and the solid feed rate (Na2CO3: 153 kg / h) are controlled according to turbidity and floc particle size. 2+The total hardness, pH, alkalinity, turbidity, and floc particle size are used to dynamically verify the chemical dosing / influent index mass equivalent coefficients based on a regression model (i.e., fitting a large amount of data on influent and effluent water quality (concentration) and chemical dosage in the formula during the operation phase through a mathematical model for chemical dosing calculation). This verification is then fed back to the mathematical model and chemical dosage calculation in real time through the processing module, allowing for fine-tuning of the Na2CO3 dosage, NaOH dosage, dosing pump flow rate, and solid feed rate.

[0073] Low-value abnormal operating conditions in the dual-alkali softening and sedimentation unit include abnormally high turbidity or poor floc settling, with online monitoring parameters including turbidity and floc particle size distribution. High-value abnormal operating conditions include scaling in the tank and pipe blockage, with online monitoring parameters including inlet and outlet flow rates. The normal inlet flow rate is 52.5 m³ / h. 3 / h, when the effluent turbidity is >10 NTU or the percentage of floc particles with a diameter greater than 50 μm is <85%, it is judged as a low-value anomaly. The treatment of the dual-alkali softening and sedimentation unit under the condition of low-value anomalies in effluent turbidity and floc particle size distribution is: increase the dosage of coagulant and flocculant; when the instantaneous flow rate of the effluent pipe is monitored to be less than 39.3 m³ / h, it is considered a low-value anomaly. 3 When the value is / h, it is determined to be a high value anomaly. The handling of the high value anomaly in the dual alkali softening and precipitation unit includes shutdown and maintenance: triggering an alarm, and after receiving the information, the management personnel of the upper management unit organize inspections of the water tank, equipment, pipelines, etc., scale cleaning or emergency discharge, etc.

[0074] Step 3: Real-time monitoring of SiO2 (21.8 mg / L), pH (10.6), and flow rate (47.6 m³ / L) at the inlet of the silica removal unit. 3 / h), set the SiO2 (10mg / L) and pH (11.0) of the effluent quality, and monitor SiO2 (8.6mg / L), pH (11.0), turbidity (≤10NTU) and floc size (percentage of particles with a diameter greater than 50μm ≥85%) at the effluent end in real time.

[0075] Based on the MgCl2 reagent dosing calculation model: , A MgCl2 =10.2.

[0076] Based on the NaOH reagent dosing calculation model: , A NaOH(Si) =10.3.

[0077] The dosage of the reagents (MgCl2: 190 mg / L, NaOH: 420 mg / L), the flow rate of the dosing pump (MgCl2: 90 L / h, mass concentration: 10%; NaOH: 67 L / h, mass concentration: 30%), and the solid feed rate (MgCl2: 9.0 kg / h) were calculated. The dosage of PFS and PAM (PFS: 50 mg / L, PAM: 2 mg / L), the flow rate of the dosing pump (PFS: 2.38 L / h, PAM: 95.2 L / h), and the solid feed rate (PFS: 2.38 kg / h, PAM: 0.1 kg / h) were controlled according to the turbidity and floc particle size. The system monitors the SiO2, pH, turbidity, and floc size of the effluent in real time using online monitoring instruments at the effluent end. Based on a regression model (i.e., fitting a large amount of data on the influent and effluent water quality (concentration) and dosage during operation using a mathematical model for calculating chemical dosing to obtain the chemical dosing / influent / effluent index mass equivalent coefficient), the chemical dosing / influent index mass equivalent coefficient is dynamically verified. This verification is then fed back to the mathematical model and chemical dosing calculation in real time through the processing module, allowing for fine-tuning of the MgCl2 dosage, NaOH dosage, dosing pump flow rate, and solid feed rate.

[0078] Low-value abnormal operating conditions in the desiliconization unit include abnormally high turbidity or poor floc settling, with online monitoring parameters including turbidity and floc particle size distribution. High-value abnormal operating conditions include scaling in the tank and pipe blockage, with online monitoring parameters including inlet and outlet flow rates. The normal inlet flow rate is monitored to be 47.6 m³ / h. 3 / h, when the effluent turbidity is >10 NTU or the percentage of floc particles with a diameter greater than 50 μm is <85%, it is judged as a low-value anomaly. The treatment of the silica removal unit under the condition of low-value anomalies in effluent turbidity and floc particle size distribution is: increase the dosage of coagulant and flocculant; when the instantaneous flow rate of the effluent pipe is monitored to be less than 35.7 m³ / h, it is considered a low-value anomaly. 3 / h is determined to be a high value anomaly. The handling of the high value anomaly in the dual alkali softening and precipitation unit includes shutdown and maintenance: triggering an alarm, and after receiving the information, the management personnel of the upper management unit organize inspections of the water tank, equipment, pipelines, etc., scale cleaning or emergency discharge, etc.

[0079] Step 4: The pH (11.0) and alkalinity (CO3) of the inlet water of the decarbonization unit are monitored in real time. 2- (116 mg / L) and flow rate (43.1 m³ / L) 3 / h), set the pH (7.0) and alkalinity (CO3) at the outlet water. 2- (0 mg / L), pH (7.0) and alkalinity (CO3) were monitored in real time at the outlet. 2- 0 mg / L, HCO3 - (52 mg / L)

[0080] Based on the HCl reagent dosing calculation model: , A HCl =1.74.

[0081] The dosage of the chemical (HCl: 308 mg / L, 30% industrial hydrochloric acid) and the flow rate of the dosing pump (44 L / h) were calculated. The pH and alkalinity of the effluent were monitored in real-time by online instruments at the outlet. Based on a regression model (i.e., fitting a large amount of data on the influent and effluent water quality (concentration) and dosage during operation to obtain the chemical dosage / influent / effluent index mass equivalent coefficient), the chemical dosage / influent index mass equivalent coefficient was dynamically verified. This verification was then fed back in real-time to the mathematical model and chemical dosage calculation via the processing module, affecting the HCl dosage and the dosing pump flow rate.

[0082] Step 5: The flow rate (43.2 m³ / h) at the inlet of the ceramic membrane filtration unit was monitored in real time. 3 Under normal operating conditions, the transmembrane pressure difference is between 0 and 0.05 MPa, and the flow difference between the influent and product water sides is <6.5 m³ / h. 3 / h, effluent turbidity ≤3.0NTU.

[0083] Online monitoring of the inlet and outlet pressures of the ceramic membrane filtration unit and the inlet and outlet flow rates (normally 43.2 m³ / h). 3 / h); High-value abnormal operating conditions are characterized by an abnormal increase in turbidity, with turbidity being the online monitoring parameter. The treatment for low-value abnormal operating conditions of the ceramic membrane filtration unit's transmembrane pressure difference and permeate flow rate is backwashing and chemical cleaning, respectively: When a sudden change in transmembrane pressure difference > 0.05 MPa is detected, it is determined to be a low-value abnormality, and the backwashing program is automatically triggered to backwash the ceramic membrane with a set flushing water volume, repeating 5 times. After each flush, drainage and backwash tank replenishment are initiated; when a sudden drop in permeate flow rate ≥ 6.5 m³ / h is detected... 3 When the turbidity is / h, it is determined to be a low value anomaly, and the chemical cleaning program is automatically triggered to automatically clean the membrane module with the designed chemical flushing volume. The handling of the ceramic membrane filter unit under high value anomaly conditions is to shut down for maintenance: when the effluent turbidity >3.0 NTU, an alarm is triggered, and after receiving the information, the upper management personnel organize the replacement of the membrane module.

[0084] Step 6: Real-time monitoring of Ca at the inlet of the ion exchange unit. 2+ (22 mg / L), flow rate (41.7 m³ / L) 3 / h), under normal operating conditions, the total hardness of the effluent is ≤5mg / L.

[0085] Online monitoring of the total hardness and cumulative flow of the effluent from the ion exchange unit; setting the ion exchange resin regeneration value to a cumulative flow of 720 m³ / h.3 The low-value abnormal operating condition of the ion exchange unit is defined as the cumulative permeate flow reaching the set regeneration value, with the online monitoring parameter being the effluent flow rate; the high-value abnormal operating condition is defined as the total hardness of the effluent > 5 mg / L, with the online monitoring parameter being the total hardness. The control of the ion exchange unit under the low-value abnormal operating condition includes resin regeneration: when the cumulative permeate flow is monitored to be ≥ 720 mg / L... 3 When the total hardness of the effluent is detected to be >5mg / L, it is determined to be an abnormal low value and the resin regeneration program is automatically started; when the total hardness of the effluent is detected to be >5mg / L, it is determined to be an abnormal high value and an alarm is triggered. After receiving the information, the management personnel of the upper management unit organize the replacement of the ion exchange resin.

[0086] Step 7: The COD level (219 mg / L) was monitored in real time at the inlet of the COD purification membrane unit, and the inlet flow rate was 40.9 m³ / L. 3 / h, COD (142mg / L) was monitored in real time at the outlet, and the product water flow rate was 38.8m³ / h. 3 / h, under normal operating conditions the transmembrane pressure difference is in the range of 0 to 0.1 MPa.

[0087] Low-value abnormal operating conditions of the COD purification membrane unit are characterized by excessive transmembrane pressure difference and a sudden drop in permeate flow rate. Online monitoring parameters include the inlet and outlet pressures of the membrane module and the permeate flow rate. High-value abnormal operating conditions are characterized by excessive COD in the effluent. Online monitoring parameters include the COD at both the inlet and outlet ends. The control measure for low-value abnormal operating conditions of the COD purification membrane unit is shutdown and flushing: when the transmembrane pressure difference between the inlet and concentrate > 0.21 MPa or the permeate flow rate decreases by ≥ 5.8 m³ / min. 3 When COD reaches 175 mg / L, it is determined to be a low value abnormality, and the lower-level controller of the COD purification membrane unit automatically triggers the shutdown flushing procedure; the control of the COD purification membrane unit under the high value abnormality condition is to shut down for maintenance. When COD>175 mg / L, it is determined to be a high value abnormality, and the lower-level controller of the COD purification membrane unit triggers an alarm to the upper-level management unit. After receiving the information, the upper-level management personnel organize the replacement of the membrane module.

[0088] Step 8: The flow rate (44.1 m³ / h) at the inlet of the nanofiltration unit was monitored in real time. 3 / h), SO4 2- (9545 mg / L); the permeate flow rate was monitored to be (35.3 m³ / L). 3 / h), SO4 2- (477 mg / L); SO4 on the concentrate side 2- (45818 mg / L), conductivity (66.8 mS / cm), and under normal operating conditions, the transmembrane pressure difference between feed water and concentrate is between 0 and 0.1 MPa.

[0089] The low-value abnormal operating conditions of the nanofiltration unit are abnormal transmembrane pressure difference and a sudden drop in permeate flow rate, with online monitoring parameters being the inlet and outlet pressures of the inter-stage pump and the influent and permeate flow rates, respectively. The high-value abnormal operating condition is an abnormal increase in conductivity, with online monitoring parameters being the conductivity of the influent and concentrate sides. The control for the low-value abnormal operating conditions of the nanofiltration unit is shutdown flushing: when the transmembrane pressure difference between the influent and concentrate is >0.21MPa or the permeate flow rate decreases by ≥5.3m³. 3 When the conductivity is / h, it is determined to be a low value abnormality, and the shutdown flushing procedure is automatically triggered; the control of the nanofiltration unit under high value abnormality is to shut down for maintenance: when the conductivity of the concentrate side is >100mS / cm, it is determined to be a high value abnormality, triggering an alarm. After receiving the information, the upper management personnel organize the replacement of the membrane module.

[0090] Step 9, the evaporation and crystallization unit processes 30.6 m³ of water. 3 / h, total evaporation capacity 29m³ 3 / h, salt output 1 m 3 / h, salt moisture content 3%; online monitoring of parameters such as condensate drainage conductivity, feed flow rate, and pressure difference before and after the demister. Under normal operating conditions, condensate drainage conductivity (0~10μS / cm), feed flow rate (30.6m³ / h), and feed flow rate (30.6m³ / h) are measured. 3 / h), pressure difference across the demister (0~5kPa).

[0091] Abnormal operating conditions of the evaporation crystallization unit include: severe secondary steam foam entrainment, blockage of the feed pipe or feed plate heat exchanger, and demister blockage. The abnormal conditions and handling methods are as follows: Severe secondary steam foam entrainment: When the conductivity > 10 μS / cm, it is judged as a low-value abnormality, and the defoamer dosing device is automatically controlled to add defoamer; if the conductivity is still > 10 μS / cm after adding defoamer, it is judged as a high-value abnormality, triggering an alarm to feed feedback to the upper management computer, and arranging for manual inspection and cleaning of the demister screen. Blockage of the feed pipe or feed plate heat exchanger: When the feed flow rate < 26.0 m³ / cm... 3 When the feed flow rate is <15.3m³ / h, it is considered a low value abnormality, and the pipeline flushing program is automatically started; 3 When the pressure difference is / h, it is determined to be a high value abnormality, triggering an alarm. After receiving the information, the management personnel of the upper management unit organize the unblocking of the feed pipe. Demister blockage: If the pressure difference before and after the demister is >5kPa, it is determined to be a low value abnormality, triggering a shutdown flushing, and automatically opening the demister screen cleaning switch valve for 60s; if the pressure difference before and after the demister is still >5kPa after flushing, it is determined to be a high value abnormality, triggering an alarm, and arranging for manual opening of the screen to check the blockage and disassembly and cleaning.

[0092] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0093] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A dosing system for a zero-discharge process of polysilicon wastewater, characterized in that, It includes a dosing control system and multiple chemical treatment units. Each chemical treatment unit is equipped with a dosing unit, an inlet monitoring unit, and an outlet detection unit. The inlet monitoring unit is used to monitor the concentration of the index value of the inlet water, and the outlet detection unit is used to detect the concentration of the index value of the outlet water. The dosing unit, the inlet detection unit, and the outlet detection unit are all connected to the dosing control system. Based on the deviation between the set target values ​​for effluent water quality and the detected target values ​​for effluent water quality indicators, the dosage of chemicals is calculated using a mathematical model for chemical dosing. The dosing control system then adjusts the dosage of chemicals in the dosing unit. The mathematical model for chemical dosing calculation is as follows: ； in, C m The dosage of each agent is in mg / L; A m The mass equivalent coefficients for each reagent dosage / influent water index are given. A m The range is 0.9 to 11; M m The relative molecular weights of the various drugs are given in g / mol. C a0i The concentration values ​​of the indicators at each inlet are in mg / L; C aei The concentration values ​​of the indicators at each outlet are in mg / L; M ai The relative molecular weight, in g / mol, represents the index values ​​for each inlet and outlet. n ai The index values ​​for ion charge at each inlet and outlet are: n m The characteristic ionic charge number of each added agent; C m0 The concentration of ions with the same characteristics as each inlet and each added agent, in mg / L; M m0 The relative molecular weight (g / mol) of ions with the same characteristics as each water inlet and each added agent.

2. The dosing system for zero-discharge process of polysilicon wastewater according to claim 1, characterized in that, The dosing unit is equipped with a dosing pump, which controls the flow rate of the chemical dosage. The formula for calculating the flow rate of the dosage is as follows: ； in, Q A The flow rate for the added amount, m 3 / h; Q 0 The inlet flow rate of this control unit is m. 3 / h; ω To prepare the mass concentration of the drug.

3. The dosing system for zero-discharge process of polysilicon wastewater according to claim 1, characterized in that, The dosing control system is based on a mathematical model for calculating chemical dosing. It integrates data from the inlet monitoring unit and the outlet detection unit to establish a water quality-chemical dosage regression model. The regression model is used to dynamically verify the chemical dosing / inlet index quality equivalent coefficient. The data is then fed back to the mathematical model and chemical dosing calculation in real time through the processing module to dynamically adjust the chemical dosing.

4. The dosing system for zero-discharge process of polysilicon wastewater according to claim 1, characterized in that, The chemical treatment unit includes a sodium sulfate softening and precipitation unit, a dual-alkali softening and precipitation unit, a silicon removal unit, and a decarbonization unit connected in sequence; the sodium sulfate softening and precipitation unit adds sodium sulfate to remove calcium from the wastewater. 2+ In the dual-alkali softening and precipitation unit, sodium carbonate, sodium hydroxide, coagulants, and flocculants are added to further remove calcium from the wastewater. 2+ Mg 2+ The silica removal unit adds magnesium salts, sodium hydroxide, coagulants, and flocculants to remove silica from the wastewater; the decarbonization unit adds acid to adjust the pH of the wastewater to a neutral range.

5. The dosing system for zero-discharge process of polysilicon wastewater according to claim 4, characterized in that, The inlet monitoring unit and outlet detection unit of the sodium sulfate softening and precipitation unit are used to monitor Ca2+. 2+ and SO4 2- The indicator value and the calculation model for sodium sulfate dosage are as follows: ； in, A Na2SO4 It ranges from 1.2 to 1.

7.

6. The dosing system for zero-discharge process of polysilicon wastewater according to claim 4, characterized in that, The inlet monitoring unit of the dual-alkali softening and sedimentation unit is used to monitor Ca. 2+ Total hardness, pH, and alkalinity; the outlet water detection unit is used to monitor Ca. 2+ Total hardness, pH alkalinity, and effluent turbidity values; The calculation model for sodium carbonate dosage is as follows: ； in, A Na2CO3 The value is between 1.15 and 1.

30. Sodium hydroxide dosing calculation model: ； in, A NaOH(Ca) The value is 1.2 to 2.

7. Inlet and outlet C a(Mg²⁺) Based on total hardness and C a(Ca²⁺) The calculation shows that: ； The dosage of coagulant and flocculant should be adjusted according to the turbidity of the effluent, with a turbidity ≤10 NTU.

7. The dosing system for zero-discharge process of polysilicon wastewater according to claim 4, characterized in that, The inlet monitoring unit of the desiliconization unit is used to monitor SiO2 and pH values, while the outlet detection unit is used to monitor SiO2, pH, turbidity, and floc particle size. The added magnesium salt is magnesium chloride, and the calculation model for magnesium chloride dosage is as follows: ； in, A MgCl2 It ranges from 5 to 11; Sodium hydroxide dosing calculation model: ； in, A NaOH(Si) The range is 4 to 11. The dosage of coagulant and flocculant is adjusted according to the effluent turbidity and floc particle size. The turbidity is ≤10 NTU and the percentage of floc particles with a particle size greater than 50 μm is ≥85%.

8. The dosing system for zero-discharge process of polysilicon wastewater according to claim 4, characterized in that, The inlet and outlet monitoring units of the decarbonization unit are used to monitor pH and alkalinity values, respectively. The added acid is hydrochloric acid, and the hydrochloric acid dosage calculation model is as follows: ； in, A HCl The value ranges from 0.9 to 1.

8.

9. The dosing system for zero-discharge process of polysilicon wastewater according to claim 4, characterized in that, A ceramic membrane filtration unit is installed between the silicon removal unit and the decarbonization unit. The ceramic membrane filtration unit is used to remove suspended solids in the wastewater. After the decarbonization unit, there are sequentially an ion exchange unit, a COD purification membrane unit, a nanofiltration unit, and an evaporation crystallization unit. The ion exchange unit is used to further remove hardness from the water. The COD purification membrane unit is used to remove COD from the wastewater. The nanofiltration unit is used to separate and remove divalent anions from the wastewater. The evaporation crystallization unit is used to concentrate and crystallize dissolved salts, thereby achieving solute and solvent separation and "zero discharge" of polysilicon wastewater.

10. A control and treatment system for a zero-discharge process of polysilicon wastewater, characterized in that, Includes a control system main control unit and a dosing system as described in any one of claims 1 to 9; The main control unit of the control system is connected to the dosing system and the backup processing unit. The main control unit includes an upper management computer and a lower control computer. The upper management computer is used to manually control the operating parameters of the lower control computer and handle abnormal operating conditions of the lower control computer. The lower control computer is used to monitor the abnormal operating conditions of each agent processing unit in the dosing system, and after judgment, it will handle the situation or feed back to the upper management computer and switch to the backup processing unit.

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