Method for on-line monitoring of trace amounts of chlorine ions in water vapor and related devices

Abstract

The application discloses a kind of water vapor trace chlorine ion online monitoring method and related device, water sample is pretreated by water sample pretreatment unit, hydrogen conductivity measurement unit is measured to water sample, trace chlorine ion online detection module removes interference anion in water sample;Temperature and pressure of trace chlorine ion online detection module effluent are collected by multi-parameter acquisition and signal processing unit, then the dynamic mathematical model of the relationship between chlorine ion concentration and hydrogen conductivity in modeling and concentration solving module is called, chlorine ion concentration is calculated, and the chlorine ion concentration calculated is output by data traceability and transmission module, the method and related device can be based on hydrogen conductivity-chlorine ion quantitative relationship model, and water vapor trace chlorine ion online monitoring is carried out by combining interference factor decoupling and dynamic correction technology.

Description

Technical Field

[0001] This invention belongs to the field of trace chloride ion detection in water vapor, and relates to an online monitoring method and related device for trace chloride ions in water vapor. Background Technology

[0002] In the steam-water systems of thermal power plants, nuclear power plants, and high-parameter industrial boilers, chloride ions (Cl...) - Chloride ions (CCl3) are among the most destructive impurity ions that induce stress corrosion cracking, pitting corrosion, and intergranular corrosion. Even fluctuations in their trace concentration (μg / L level) can pose a serious threat to the safe operation of thermal power equipment. According to standards such as "Water and Steam Quality of Thermal Power Generating Units and Steam Power Equipment" (GB / T12145), strict control requirements are set for the chloride ion concentration in the water and steam systems of supercritical units (e.g., feedwater Cl3). - <2μg / L, vapor Cl - (<1μg / L). Therefore, achieving real-time, online, and highly sensitive monitoring of trace chloride ions in water vapor is crucial for corrosion prevention and control.

[0003] Currently, the main technical shortcomings of methods for detecting trace chloride ions in water vapor are as follows: 1) Ion chromatography: As a standard laboratory method, it can accurately quantify chloride ions as low as 0.1 μg / L, but the equipment is expensive, maintenance is complex, the chromatographic column and eluent need to be replaced regularly, and the single analysis cycle is long (usually 20-40 minutes), which cannot achieve online continuous monitoring, and cannot meet the needs of rapid response during the start-up and shutdown of the unit.

[0004] 2) Ion-selective electrode method: The detection limit of chloride ion selective electrodes is usually 0.5-1.0 mg / L, which is far from meeting the detection requirements at the trace level (μg / L), and is also affected by other ions in the water sample (such as OH-). - ,Br - It causes severe interference and is not suitable for high-purity water systems.

[0005] 3) Spectrophotometric methods (such as the mercuric thiocyanate method): The operation is cumbersome, the reagents used contain toxic substances such as mercury, the waste liquid is difficult to treat, and the detection limit is usually only at the level of 0.1 mg / L, resulting in insufficient sensitivity.

[0006] 4) Direct hydrogen conductivity method: Although hydrogen conductivity (conductivity after cation exchange) can comprehensively reflect all anionic impurities (Cl) in the water sample... - SO4² - CO3² - HCOO - The total amount of chloride ions (etc.) is not significant, but the specific contribution of chloride ions cannot be distinguished. Furthermore, it is strongly interfered with by other anions (especially carbonate / bicarbonate ions), resulting in a lack of effective decoupling methods between chloride ions and hydrogen conductivity.

[0007] In practical industrial applications, some researchers have observed a certain empirical relationship between chloride ion concentration and hydrogen conductivity, but this relationship is often limited to specific water quality conditions. No general mathematical model that can be solved online has been established, nor has a complete automated monitoring system been formed.

[0008] Therefore, there is an urgent need to develop an online monitoring method and system for trace chloride ions in water vapor based on a hydrogen conductivity-chloride ion quantitative relationship model, combined with interference factor decoupling and dynamic correction technology, to provide a feasible, accurate and economical solution for non-chromatographic online trace chloride ion monitoring. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and related device for online monitoring of trace chloride ions in water vapor. This method and device can perform online monitoring of trace chloride ions in water vapor based on the hydrogen conductivity-chloride ion quantitative relationship model and combined with interference factor decoupling and dynamic correction technology.

[0010] To achieve the above objectives, this invention discloses an online monitoring system for trace chloride ions in water vapor, comprising a water sample pretreatment unit, a hydrogen conductivity measurement unit, a trace chloride ion online detection module, a multi-parameter acquisition and signal processing unit, a modeling and concentration calculation module, and a data traceability and transmission module. The water sample pretreatment unit pretreatments the water sample; the hydrogen conductivity measurement unit measures the hydrogen conductivity of the water sample; and the trace chloride ion online detection module removes interfering anions from the water sample. The multi-parameter acquisition and signal processing unit acquires the temperature and pressure of the water effluent from the trace chloride ion online detection module. The dynamic mathematical model relating chloride ion concentration and hydrogen conductivity in the modeling and concentration calculation module is then used to calculate the chloride ion concentration. Finally, the calculated chloride ion concentration is output through the data traceability and transmission module.

[0011] Furthermore, the water sample pretreatment unit includes a pressure reducing valve, a constant flow device, a degassing module, and a precision filtration module connected in sequence.

[0012] Furthermore, the hydrogen conductivity measurement unit includes a cation exchange column and a conductivity electrode. After the water sample flows through the cation exchange column, the cations are converted by H+. + In the displacement process, the acid corresponding to the anions in the effluent from the exchange column contributes to the conductivity, and the hydrogen conductivity value (CC) is measured by a conductivity electrode.

[0013] Furthermore, the trace chloride ion online detection module uses an ion chromatography microcolumn or an online ion selective enrichment device to remove interfering anions.

[0014] Furthermore, the data traceability and transmission module uploads the calculated trace chloride ion concentration to the central control center or cloud platform via fieldbus or 4G / 5G wireless network, and links with the unit's DCS.

[0015] This invention discloses an online monitoring method for trace chloride ions in water vapor, characterized by being based on an online monitoring system for trace chloride ions in water vapor, and comprising the following steps: The water sample first flows through depressurization, cooling, degassing, and filtration, and then enters the hydrogen conductivity measurement unit to measure the hydrogen conductivity CC_corr. Next, it enters the trace chloride ion online detection module to remove interfering anions, and then the additional hydrogen conductivity ΔCC_interfer caused by interfering anions is measured again. Then, the dynamic mathematical model of the relationship between chloride ion concentration and hydrogen conductivity in the modeling and concentration calculation module is called to calculate the chloride ion concentration, and the calculated chloride ion concentration is output through the data traceability and transmission module.

[0016] Furthermore, the dynamic mathematical model for the relationship between chloride ion concentration and hydrogen conductivity is as follows: C_Cl - =α·exp(β·CC_corr)+γ·ΔCC_interfer(1) Where α, β, and γ are model coefficients.

[0017] Furthermore, the water sample pretreatment unit includes a pressure reducing valve, a constant flow device, a degassing module, and a precision filtration module connected in sequence.

[0018] Furthermore, the hydrogen conductivity measurement unit includes a cation exchange column and a conductivity electrode. After the water sample flows through the cation exchange column, the cations are converted by H+. + In the displacement process, the acid corresponding to the anions in the effluent from the exchange column contributes to the conductivity, and the hydrogen conductivity value (CC) is measured by a conductivity electrode.

[0019] Furthermore, the trace chloride ion online detection module uses an ion chromatography microcolumn or an online ion selective enrichment device to remove interfering anions.

[0020] The present invention has the following beneficial effects: In practical operation, the online monitoring method and related device for trace chloride ions in water vapor described in this invention measures the hydrogen conductivity CC_corr through a hydrogen conductivity measurement unit; then, it enters the trace chloride ion online detection module to remove interfering anions, and then measures the additional hydrogen conductivity ΔCC_interfer caused by the interfering anions again; finally, it calls the dynamic mathematical model of the relationship between chloride ion concentration and hydrogen conductivity in the modeling and concentration calculation module to calculate the chloride ion concentration. Thus, based on the hydrogen conductivity-chloride ion quantitative relationship model, and combined with interference factor decoupling and dynamic correction technology, online monitoring of trace chloride ions in water vapor is performed, which is highly practical. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a structural diagram of the present invention. Detailed Implementation

[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, not all, of the embodiments of the present invention. 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] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0025] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0027] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0028] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0031] refer to Figure 1The online monitoring system for trace chloride ions in water vapor described in this invention includes: 1) Water sample pretreatment unit: including pressure reducing valve, constant flow device, degassing module and precision filtration module, used to stabilize high temperature and high pressure water vapor sample to conditions suitable for online analysis (temperature 25±1℃, pressure 0.1~0.2MPa, flow rate 100~300mL / min), and remove dissolved gas and suspended particles to ensure that the water sample entering the detection unit is constant flow and clean.

[0032] 2) Hydrogen conductivity measurement unit: Includes a cation exchange column (automatically regenerable or replaceable resin column) and a high-precision conductivity electrode. After the water sample flows through the cation exchange column, the cations (NH4+) in it... + Na + Ca² + (etc.) by H + Displacement, exchange of anions (Cl) in the effluent of the column - SO4² - HCO3 - CH3COO - The corresponding acids (HCl, H2SO4, H2CO3, CH3COOH, etc.) contribute to the conductivity, and the hydrogen conductivity value (CC, unit μS / cm) is measured by the conductivity electrode.

[0033] 3) Trace chloride ion online detection module: an ion chromatography microcolumn or an online ion selective enrichment device is used in conjunction with an electrochemical detector. However, to avoid complex costs, a pretreatment structure based on online electrodialysis or membrane separation to remove interfering anions is preferred.

[0034] More specifically, the present invention integrates a pretreatment device (such as a micro pre-column or selectively permeable membrane assembly) that selectively removes interfering anions such as sulfate and bicarbonate, so that the anion component output to the detection end is mainly chloride ions, and quantification is performed in combination with a correction factor.

[0035] 4) Multi-parameter acquisition and signal processing unit: including data acquisition module, temperature / pressure sensor, chloride ion micro sensor (such as silver / silver chloride type thin film electrochemical sensor or solid contact ion selective electrode, with a detection limit of 1-2 μg / L after special optimization) and central control unit.

[0036] 5) Modeling and Concentration Calculation Module: Contains a built-in dynamic mathematical model showing the relationship between chloride ion concentration and hydrogen conductivity. Its basic form is chloride ion concentration C_Cl - =f(CC,T,pH_after,K_interference), the basic framework of this model refers to experimental calibration data, and the coefficients are determined by piecewise nonlinear fitting (such as exponential function, power function or neural network model).

[0037] The model is automatically calibrated at single or multiple points by periodically (e.g., every 24 hours) injecting chloride ion standard solution, and the model parameters are dynamically corrected.

[0038] 6) Data traceability and transmission module: The calculated trace chloride ion concentration, model parameters and instrument status are uploaded to the central control center or cloud platform via fieldbus and 4G / 5G wireless network, and linked with the unit DCS to realize advanced control functions such as alarm for exceeding the standard and linkage with chemical dosing.

[0039] The online monitoring method for trace chloride ions in water vapor based on the above system, as described in this invention, includes the following steps: Step 1: Water sample pretreatment and online hydrogen conductivity measurement; The high-temperature, high-pressure water sample first flows through a depressurization, cooling, degassing, and filtration unit, where the temperature is stabilized at 25±0.5℃, the pressure at 0.1MPa, and the flow rate at a constant 150mL / min. The water sample then enters the hydrogen conductivity measurement unit, passes through a cation exchange column, and is sent to a conductivity flow cell for continuous measurement of hydrogen conductivity (CC_meas). Simultaneously, a temperature sensor monitors the water sample temperature in real time for subsequent conductivity temperature compensation (compensated to 25℃).

[0040] Step 2: Selective removal of interfering anions and enrichment of chloride ions; To overcome background interference from non-chloride ions such as sulfate and bicarbonate in the hydrogen conductivity signal, a selective removal device (such as a microcolumn pre-filled with selective adsorption resin) is installed in parallel or in series. The control unit directs a portion of the bypass flow into this removal device by switching a multi-way valve, and then introduces the interference-removed water sample into a dedicated chloride ion sensor or a micro-electrochemical cell. Simultaneously, the system collects the difference in hydrogen conductivity decrease during this process; this difference can be used to estimate the total contribution of interfering ions.

[0041] Step 3: Real-time calculation of chloride ion concentration based on the relational model; Based on the aforementioned preprocessing and measured CC values, the following simplified equivalent model is established: C_Cl - =α·exp(β·CC_corr)+γ·ΔCC_interfer(1) Where CC_corr is the hydrogen conductivity value equivalent to the pure chloride ion contribution after compensation for temperature, pressure, and flow rate, which is the total CC minus the online estimated interference term (SO4²). - HCO3 - (etc.) are obtained; ΔCC_interfer reflects the additional conductivity caused by anions other than chloride ions; α, β, γ are model coefficients, which are determined by automatic calibration experiments at at least three standard chloride ion concentration points.

[0042] Meanwhile, in order to improve the accuracy in the low concentration range, the system introduces a low concentration correction factor and uses the known offset method or standard addition method to verify the model bias in the sensitive range.

[0043] Step 4: Online automatic calibration and model update; 1) Zero-point calibration: Periodically (e.g., every 12 hours), introduce a "zero standard solution" (chloride ion concentration < 0.1 μg / L) that has undergone deep dechlorination treatment, record the reference hydrogen conductivity CC_zero, and eliminate drift.

[0044] 2) Range / slope calibration: The system automatically injects chloride ion standard solutions (concentrations such as 2.0 μg / L, 5.0 μg / L and 10.0 μg / L) daily for multi-point calibration; after calibration, the system automatically fits the model parameters (α, β, γ) using the least squares method and stores the updated model parameters in non-volatile memory.

[0045] 3) Dual-channel comparison redundancy: When the reliability of the chloride ion sensor decreases (such as when the response time is prolonged), the system uses the historical model to calculate the hydrogen conductivity as a reference and issues an alarm to prompt maintenance.

[0046] Step 5: Reliability verification and output; After each detection cycle (e.g., 15 minutes), the system automatically performs an internal consistency check: comparing the chloride ion concentration calculated from the model value C_Cl. - (model) and the measured value of C_Cl by a dedicated chloride ion sensor - The system will flag the data as "suspicious" if the deviation between the two sensors exceeds ±20%, and will automatically trigger an additional calibration process (such as rapid single-point or two-point verification). If the deviation is corrected after calibration, the normal output will be restored; otherwise, the system will notify the maintenance personnel to perform maintenance.

[0047] Ultimately, valid data is uploaded to the DCS or SIS in real time using protocols such as 4-20mA, Modbus, and OPCUA, and alarm thresholds can be set (e.g., Cl). - Warning for concentrations >1 μg / L, alarm for concentrations >2 μg / L.

[0048] In this embodiment, the cation exchange resin column in the hydrogen conductivity measurement unit can be designed to be automatically regenerated (electro-regenerated or chemically regenerated) to achieve long-term unattended continuous operation.

[0049] In this embodiment, the chloride ion model is not fixed, but adopts an adaptive learning algorithm (such as recursive least squares RLS) to make full use of the results of each automatic calibration or manual test comparison, and updates the model parameters in real time or at regular intervals, so that the system is adaptive to changes in water quality (drift of source water ion composition).

[0050] In this embodiment, to eliminate the influence of carbonate / bicarbonate ions, a degassing membrane module can be connected in series before the hydrogen conductivity measurement to remove CO2 from the water sample, and then the "degassed hydrogen conductivity" is measured, thereby minimizing CO2 interference and effectively highlighting the contribution of non-volatile anions such as chloride and sulfate ions.

[0051] In this embodiment, an online sulfate monitoring module (such as ultraviolet detection or selective electrochemical methods) can be embedded in the system for real-time calculation of SO4² in the interference model. - The contributions of CC and Cl - A multivariate calibration matrix is ​​formed to improve the accuracy of chloride ion inversion under complex water quality conditions.

[0052] Example 1 This embodiment is used for online monitoring of trace chloride ions in the feedwater system of a supercritical unit.

[0053] Application scenario: A supercritical 600MW unit uses oxygenated feedwater (OT) treatment, which requires real-time monitoring of chloride ion concentration in the feedwater to ensure it is below the warning value of 2.0μg / L.

[0054] System configuration: The online monitoring system for trace chloride ions in water vapor based on the relationship model between hydrogen conductivity and chloride ions described in this invention includes: 1) High-temperature and high-pressure sampling frame (including pressure reduction and cooling to 25℃); 2) Automatic constant flow device (flow rate 150 mL / min); 3) Cation exchange column (automatic regeneration type); 4) Degassing membrane module (CO2 removal); 5) Selective adsorption pre-column (packed with SO4²⁻) - (Strongly adsorbed macroporous anion exchange resin); 6) High-precision conductivity electrode (range 0-10μS / cm, accuracy 0.001μS / cm). 7) Trace chloride ion electrochemical sensor (Ag / AgCl reference electrode system, detection limit 0.5 μg / L); 8) The PLC controller has a built-in relational model and adaptive algorithm; 9) Industrial control computer and 4G communication module.

[0055] Operating steps: System startup and self-test: The PLC performs a self-test on the pump and valve components, sensor zero point, and temperature stability upon startup. If CC_zero exceeds the set range (>0.055μS / cm corresponds to the standard value for deionized water), the system automatically stops and prompts for maintenance.

[0056] 1) Continuous measurement cycle (once every 15 minutes): After being processed by the sampling rack, the high-pressure water sample flows through the degassing membrane to remove CO2 and then flows into the cation exchange column to measure the degassing hydrogen conductivity CC_D.

[0057] A bypass flow was set up through the selective adsorption pre-column (regenerated every 6 hours), and the conductivity CC_ads after adsorption was measured. The difference between the two values, ΔCC_interfer, is approximately the contribution of interfering ions such as sulfate.

[0058] Using formula C_Cl - =α·exp(β·(CC_D-ΔCC_interfer-CC_zero))+γ·ΔCC_interfer is used for real-time calculation, where α, β, and γ are the model coefficients after the last calibration.

[0059] The built-in micro chloride ion sensor continuously reads C_sensor as a comparison reference.

[0060] 2) Automatic calibration: The system automatically switches to calibration mode at 2:00 AM every day: low concentration standard solutions (1.0 μg / L, 5.0 μg / L, 10.0 μg / L) and zero standard solution (<0.1 μg / L) are introduced in sequence, the changes in hydrogen conductivity contributed by pure chloride ions at each concentration are recorded, α, β, γ are refitted using the least squares method, and the timestamp and model version are updated.

[0061] 3) Exception handling and alarms: When C_Cl - The system issues a pre-alarm when the concentration is >1.8 μg / L; and a critical alarm when the concentration is >2.2 μg / L, along with prompts to increase wastewater discharge or optimize chemical dosing. If C_sensor and C_Cl - If the deviation remains greater than 25%, the system will automatically trigger an emergency single-point calibration (5μg / L standard solution). If the deviation converges after calibration, the system will continue to operate; otherwise, a fault alarm will be triggered, prompting the system to perform maintenance.

[0062] 4) Data upload and analysis: Every 15 minutes, a set of data (chloride ion concentration, hydrogen conductivity, estimated contribution of interfering ions, and sensor self-test status) is packaged by the PLC and uploaded to the plant-level SIS system via OPCUA, and real-time trend curves and historical data are displayed in the central control room.

[0063] Implementation results: After 30 days of continuous operation, data compared with offline sampling data from ion chromatography (twice a week) showed that the relative error of the online chloride ion monitoring values ​​of this system was within ±15%, with a correlation coefficient R² = 0.97. During the unit's deep peak shaving period, no corrosion caused by excessive chloride ions was recorded. The system underwent 60 automatic calibrations with a success rate of 98.3%, extending the manual maintenance cycle to once a month, significantly reducing operating costs compared to ion chromatography. This solution effectively supports the online monitoring of chloride ions, a key indicator for corrosion prevention and control in thermal equipment, filling a technical gap in online chloride ion monitoring in power plants.

[0064] This invention has the following characteristics: 1) Dynamic chloride ion inversion algorithm based on a relational model: For the first time, a nonlinear relationship model (exponential form) between chloride ion concentration and hydrogen conductivity is incorporated into the online monitoring system. Combined with online subtraction of interfering ions and a temperature / pressure compensation model, the inversion solution is achieved. Unlike ordinary linear fitting, the exponential model better reflects the physicochemical laws that the sensitivity in low concentration areas and the tendency to stabilize in high concentration areas.

[0065] 2) Online selective removal of interfering ions + degassing membrane combination technology: Through the series design of micro pre-column (selectively adsorbing sulfate / bicarbonate ions) and degassing membrane (removing CO2), the main interfering factors are effectively eliminated, while the hydrogen conductivity characteristics of chloride ions are retained, providing a purer signal for model calculation.

[0066] 3) Dual-channel automatic calibration and model adaptive update mechanism: The innovative design of a dual-channel redundant structure of "chloride ion dedicated sensor + hydrogen conductivity estimation model" and the introduction of recursive least squares (RLS) or neural network online learning method to automatically optimize model parameters using calibration data and manual test results, ensuring the accuracy and robustness of long-term operation.

[0067] 4) Full-process automated integrated control: From water sample decompression, constant temperature, filtration, and degassing, to selective interference removal, hydrogen conductivity measurement, chloride ion modeling and calculation, automatic verification, and data uploading, a complete closed-loop chain is formed, which significantly improves the level of intelligent analysis.

[0068] 5) The first realization of online monitoring of trace chloride ions based on the hydrogen conductivity-chloride ion relationship model: By combining the relationship model, online automatic interference removal and multivariate calibration, the chloride ion concentration can be continuously output online (detection limit ≤1.0μg / L), filling the technical gap in the field of online trace chloride ion monitoring.

[0069] 6) Strong anti-interference capability and accurate results: SO4² is subtracted through selective removal device, degassing membrane, and modeling. - HCO3 -Compared to relying solely on hydrogen conductivity to determine chloride ions, the accuracy is significantly improved by eliminating interference from non-chloride ions, and the correlation coefficient with ion chromatography can reach over 0.95.

[0070] 7) High degree of automation and low maintenance: The system has automatic calibration, adaptive model update and fault self-diagnosis functions, which can realize long-term unattended continuous operation and reduce the cost of manual sampling and offline analysis.

[0071] 8) Fast response and good real-time performance: The single measurement cycle can be shortened to 10-15 minutes, which is far better than the 30-40 minutes of ion chromatography, meeting the needs for rapid monitoring of key corrosion indicators during unit start-up and shutdown and deep peak shaving.

[0072] 9) Easy to integrate with existing chemical instrumentation platforms: Based on standard hydrogen conductivity measurement technology, it can be quickly deployed in water vapor monitoring networks with the integration of only a few additional modules and control logic, forming a complete corrosion prevention and control solution with instruments such as computational pH and total iron monitoring.

[0073] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0074] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0075] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An online monitoring system for trace chloride ions in water vapor, characterized in that, The system includes a water sample pretreatment unit, a hydrogen conductivity measurement unit, a trace chloride ion online detection module, a multi-parameter acquisition and signal processing unit, a modeling and concentration calculation module, and a data traceability and transmission module. The water sample pretreatment unit pre-treats the water sample; the hydrogen conductivity measurement unit measures the hydrogen conductivity of the water sample; and the trace chloride ion online detection module removes interfering anions from the water sample. The multi-parameter acquisition and signal processing unit collects the temperature and pressure of the water effluent from the trace chloride ion online detection module. Then, the dynamic mathematical model of the relationship between chloride ion concentration and hydrogen conductivity in the modeling and concentration calculation module is used to calculate the chloride ion concentration. Finally, the data traceability and transmission module outputs the calculated chloride ion concentration.

2. The online monitoring system for trace chloride ions in water vapor according to claim 1, characterized in that, The water sample pretreatment unit includes a pressure reducing valve, a constant flow device, a degassing module, and a precision filtration module connected in sequence.

3. The online monitoring system for trace chloride ions in water vapor according to claim 1, characterized in that, The hydrogen conductivity measurement unit includes a cation exchange column and a conductivity electrode. After the water sample flows through the cation exchange column, the cations are converted by H+. + In the displacement process, the acid corresponding to the anions in the effluent from the exchange column contributes to the conductivity, and the hydrogen conductivity value (CC) is measured by a conductivity electrode.

4. The online monitoring system for trace chloride ions in water vapor according to claim 1, characterized in that, The trace chloride ion online detection module uses an ion chromatography microcolumn or an online ion selective enrichment device to remove interfering anions.

5. The online monitoring system for trace chloride ions in water vapor according to claim 1, characterized in that, The data traceability and transmission module uploads the calculated trace chloride ion concentration to the central control center or cloud platform via fieldbus or 4G / 5G wireless network, and links with the unit's DCS.

6. A method for online monitoring of trace chloride ions in water vapor, characterized in that, The online monitoring system for trace chloride ions in water vapor according to claim 1 includes the following steps: The water sample first flows through depressurization, cooling, degassing, and filtration, and then enters the hydrogen conductivity measurement unit to measure the hydrogen conductivity CC_corr. Next, it enters the trace chloride ion online detection module to remove interfering anions, and then the additional hydrogen conductivity ΔCC_interfer caused by interfering anions is measured again. Then, the dynamic mathematical model of the relationship between chloride ion concentration and hydrogen conductivity in the modeling and concentration calculation module is called to calculate the chloride ion concentration, and the calculated chloride ion concentration is output through the data traceability and transmission module.

7. The online monitoring method for trace chloride ions in water vapor according to claim 6, characterized in that, The dynamic mathematical model for the relationship between chloride ion concentration and hydrogen conductivity is as follows: C_Cl - =α·exp(β·CC_corr)+γ·ΔCC_interfer(1) Where α, β, and γ are model coefficients.

8. The method for online monitoring of trace chloride ions in water vapor according to claim 6, characterized in that, The water sample pretreatment unit includes a pressure reducing valve, a constant flow device, a degassing module, and a precision filtration module connected in sequence.

9. The online monitoring method for trace chloride ions in water vapor according to claim 6, characterized in that, The hydrogen conductivity measurement unit includes a cation exchange column and a conductivity electrode. After the water sample flows through the cation exchange column, the cations are converted by H+. + In the displacement process, the acid corresponding to the anions in the effluent from the exchange column contributes to the conductivity, and the hydrogen conductivity value (CC) is measured by a conductivity electrode.

10. The method for online monitoring of trace chloride ions in water vapor according to claim 6, characterized in that, The trace chloride ion online detection module uses an ion chromatography microcolumn or an online ion selective enrichment device to remove interfering anions.

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